English
Tiếng Việt
(en)The present invention relates to cellobiohydrolase variants. The present invention also relates to polynucleotides encoding the variants; nucleic acid constructs, vectors, and host cells comprising the polynucleotides; and methods of using the variants.
1.ApplicationNumber: US-201515509659-A
1.PublishNumber: US-2017292136-A1
2.Date Publish: 20171012
3.Inventor: WESTH PETER
BORCH KIM
Soerensen Trine
WINDAHL MICHAEL
MCBRAYER BRETT
4.Inventor Harmonized: WESTH PETER(DK)
BORCH KIM(DK)
Soerensen Trine(DK)
WINDAHL MICHAEL(DK)
MCBRAYER BRETT(US)
5.Country: US
6.Claims:
(en)The present invention relates to cellobiohydrolase variants. The present invention also relates to polynucleotides encoding the variants; nucleic acid constructs, vectors, and host cells comprising the polynucleotides; and methods of using the variants.
7.Description:
(en)CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority from U.S. Provisional Patent Application Ser. No. 62/047,296 filed Sep. 8, 2014. The content of this application is fully incorporated herein by reference.
REFERENCE TO A SEQUENCE LISTING
This application contains a Sequence Listing in computer readable form, which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to cellobiohydrolase variants, polynucleotides encoding the variants, and methods of producing and using the variants.
Description of the Related Art
Cellulose is a polymer of the simple sugar glucose covalently linked by beta-1,4-bonds. Many microorganisms produce enzymes that hydrolyze beta-linked glucans. These enzymes include endoglucanases, cellobiohydrolases, and beta-glucosidases. Endoglucanases digest the cellulose polymer at random locations, opening it to attack by cellobiohydrolases. Cellobiohydrolases sequentially release molecules of cellobiose from the ends of the cellulose polymer. Cellobiose is a water-soluble beta-1,4-linked dimer of glucose. Beta-glucosidases hydrolyze cellobiose to glucose.
The conversion of lignocellulosic feedstocks into ethanol has the advantages of the ready availability of large amounts of feedstock, the desirability of avoiding burning or land filling the materials, and the cleanliness of the ethanol fuel. Wood, agricultural residues, herbaceous crops, and municipal solid wastes have been considered as feedstocks for ethanol production. These materials primarily consist of cellulose, hemicellulose, and lignin. Once the lignocellulose is converted to fermentable sugars, e.g., glucose, the fermentable sugars can easily be fermented by yeast into ethanol.
WO 2011/050037 discloses Thielavia terrestris cellobiohydrolase variants with improved thermostability. WO 2011/050037 discloses Aspergillus fumigatus cellobiohydrolase variants with improved thermostability. WO 2005/028636 discloses variants of Hypocrea jecorina Cel7A cellobiohydrolase I. WO 2005/001065 discloses variants of Humicola grisea Cel7A cellobiohydrolase I, Hypocrea jecorina cellobiohydrolase I, and Scytalidium thermophilium cellobiohydrolase I. WO 2004/016760 discloses variants of Hypocrea jecorina Cel7A cellobiohydrolase I. U.S. Pat. No. 7,375,197 discloses variants of Trichoderma reesei cellobiohydrolase I.
Hybrid polypeptides comprising a cellobiohydrolase catalytic domain and a carbohydrate binding module are described in e.g., WO 2010/060056, WO 2013/091577, and WO 2014/138672.
There is a need in the art for cellobiohydrolase variants with improved properties to increase the efficiency of the saccharification of lignocellulosic feedstocks.
The present invention provides cellobiohydrolase variants with increased specific performance, polynucleotides encoding the variants, and methods of producing and using the variants.
SUMMARY OF THE INVENTION
The present invention relates to cellobiohydrolase variants, comprising deletions at two or more consecutive positions of the B2-loop, wherein the variants have cellobiohydrolase activity.
The present also invention relates to cellobiohydrolase variants, comprising a deletion at one or more positions corresponding to positions 195, 196, 197, and 198 of SEQ ID NO: 2, and wherein the variants have cellobiohydrolase activity.
The present invention also relates to isolated polynucleotides encoding the variants; nucleic acid constructs, vectors, and host cells comprising the polynucleotides; and methods of producing the variants.
The present invention also relates to processes for degrading a cellulosic material, comprising: treating the cellulosic material with an enzyme composition in the presence of a cellobiohydrolase variant of the present invention. In one aspect, the processes further comprise recovering the degraded cellulosic material.
The present invention also relates to processes of producing a fermentation product, comprising: (a) saccharifying a cellulosic material with an enzyme composition in the presence of a cellobiohydrolase variant of the present invention; (b) fermenting the saccharified cellulosic material with one or more (e.g., several) fermenting microorganisms to produce the fermentation product; and (c) recovering the fermentation product from the fermentation.
The present invention also relates to processes of fermenting a cellulosic material, comprising: fermenting the cellulosic material with one or more (e.g., several) fermenting microorganisms, wherein the cellulosic material is saccharified with an enzyme composition in the presence of a cellobiohydrolase variant of the present invention. In one aspect, the fermenting of the cellulosic material produces a fermentation product. In another aspect, the processes further comprise recovering the fermentation product from the fermentation.
BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 shows saccharide production from microcrystalline cellulose by the Trichoderma reesei wild-type cellobiohydrolase I and the cellobiohydrolase I M6 variant thereof after 5 hours at pH 5 and 25° C. The results were corrected for background sugars determined in a control sample.
FIG. 2 shows the effect of T. reesei cellobiohydrolase I M6 variant and T. reesei wild-type cellobiohydrolase I on hydrolysis of milled unwashed PCS by a cellulolytic enzyme composition at 24 hours.
FIG. 3 shows the effect of Trichoderma reesei cellobiohydrolase I M6 variant and Trichoderma reesei wild-type cellobiohydrolase I on hydrolysis of milled unwashed pretreated corn stover (PCS) by a cellulolytic enzyme composition at 48 hours.
FIG. 4 shows the effect of T. reesei cellobiohydrolase I M6 variant and T. reesei wild-type cellobiohydrolase I on hydrolysis of milled unwashed PCS by a cellulolytic enzyme composition at 72 hours.
FIG. 5 shows hydrolysis of microcrystalline cellulose by the T. reesei wild-type cellobiohydrolase I and the T. reesei cellobiohydrolase I A199*, N198A, N200G, and N200W variants. Values are shown in mM released cellobiose after 1 hour at pH 5, at 25° C. and at 1100 rpm.
FIG. 6 shows hydrolysis of microcrystalline cellulose by the Rasamsonia emersonii wild-type cellobiohydrolase I and R. emersonii cellobiohydrolase I PC1-146 variant. Values are shown in mM released cellobiose after 1 hour at pH 5, at 50° C. and at 1100 rpm.
FIG. 7 shows a comparison of the effect of the R. emersonii cellobiohydrolase I variant and R. emersonii wild-type cellobiohydrolase I on the hydrolysis of unwashed PCS (8% total solids) by a cellulase enzyme composition.
FIG. 8 shows a comparison of the effect of the R. emersonii cellobiohydrolase I PC1-146 variant and R. emersonii wild-type cellobiohydrolase I on the hydrolysis of unwashed PCS (20% total solids) by a cellulase enzyme composition.
FIG. 9 shows a comparison of the R. emersonii cellobiohydrolase I PC1-146 variant with the R. emersonii wild-type cellobiohydrolase I during hydrolysis.
FIG. 10 shows a comparison of the R. emersonii cellobiohydrolase I PC1-146 variant with the Rasamsonia emersonii wild-type cellobiohydrolase I during simultaneous saccharification and fermentation (SSF).
FIG. 11 shows a comparison of the hydrolysis of microcrystalline cellulose by the R. emersonii wild-type cellobiohydrolase I, R. emersonii PC1-147 fusion cellobiohydrolase I, and R. emersonii cellobiohydrolase I PC1-378 variant.
FIG. 12 shows a comparison of the hydrolysis of microcrystalline cellulose by the R. emersonii wild-type cellobiohydrolase I, R. emersonii PC1-147 fusion cellobiohydrolase I, and R. emersonii cellobiohydrolase I PC1-496 variant after 30 min at pH 5 and 25° C.
FIG. 13 shows a comparison of percent cellulose conversion of pretreated corn stover at 35° C., 50° C., and 60° C. by enzyme compositions comprising the R. emersonii PC1-147 fusion cellobiohydrolase I and the R. emersonii cellobiohydrolase I PC1-496 variant.
FIG. 14 shows a comparison of percent cellulose conversion of pretreated corn stover at 35° C. by enzyme compositions comprising the T. reesei cellobiohydrolase I variants TC1-213 and TC1-216 to those comprising the wild-type T. reesei cellobiohydrolase I.
FIG. 15 shows a comparison of the hydrolysis of microcrystalline cellulose by the Aspergillus fumigatus wild-type cellobiohydrolase I, and the Aspergillus fumigatus cellobiohydrolase I AC1-865 variant after 24 hours at 35° C.
DEFINITIONS
Acetylxylan esterase: The term “acetylxylan esterase” means a carboxylesterase (EC 3.1.1.72) that catalyzes the hydrolysis of acetyl groups from polymeric xylan, acetylated xylose, acetylated glucose, alpha-napthyl acetate, and p-nitrophenyl acetate. For purposes of the present invention, acetylxylan esterase activity is determined using 0.5 mM p-nitrophenylacetate as substrate in 50 mM sodium acetate pH 5.0 containing 0.01% TWEEN™ 20 (polyoxyethylene sorbitan monolaurate). One unit of acetylxylan esterase is defined as the amount of enzyme capable of releasing 1 μmole of p-nitrophenolate anion per minute at pH 5, 25° C.
Allelic variant: The term “allelic variant” means any of two or more alternative forms of a gene occupying the same chromosomal locus. Allelic variation arises naturally through mutation, and may result in polymorphism within populations. Gene mutations can be silent (no change in the encoded polypeptide) or may encode polypeptides having altered amino acid sequences. An allelic variant of a polypeptide is a polypeptide encoded by an allelic variant of a gene.
Alpha-L-arabinofuranosidase: The term “alpha-L-arabinofuranosidase” means an alpha-L-arabinofuranoside arabinofuranohydrolase (EC 3.2.1.55) that catalyzes the hydrolysis of terminal non-reducing alpha-L-arabinofuranoside residues in alpha-L-arabinosides. The enzyme acts on alpha-L-arabinofuranosides, alpha-L-arabinans containing (1,3)- and/or (1,5)-linkages, arabinoxylans, and arabinogalactans. Alpha-L-arabinofuranosidase is also known as arabinosidase, alpha-arabinosidase, alpha-L-arabinosidase, alpha-arabinofuranosidase, polysaccharide alpha-L-arabinofuranosidase, alpha-L-arabinofuranoside hydrolase, L-arabinosidase, or alpha-L-arabinanase. For purposes of the present invention, alpha-L-arabinofuranosidase activity is determined using 5 mg of medium viscosity wheat arabinoxylan (Megazyme International Ireland, Ltd., Bray, Co. Wicklow, Ireland) per ml of 100 mM sodium acetate pH 5 in a total volume of 200 μl for 30 minutes at 40° C. followed by arabinose analysis by AMINEX® HPX-87H column chromatography (Bio-Rad Laboratories, Inc., Hercules, Calif., USA).
Alpha-glucuronidase: The term “alpha-glucuronidase” means an alpha-D-glucosiduronate glucuronohydrolase (EC 3.2.1.139) that catalyzes the hydrolysis of an alpha-D-glucuronoside to D-glucuronate and an alcohol. For purposes of the present invention, alpha-glucuronidase activity is determined according to de Vries, 1998 , J. Bacteriol. 180: 243-249. One unit of alpha-glucuronidase equals the amount of enzyme capable of releasing 1 μmole of glucuronic or 4-O-methylglucuronic acid per minute at pH 5, 40° C.
B2-loop: The term “B2-loop” means the amino acids corresponding to P194 to T201 of the Trichoderma reesei Cel7A cellobiohydrolase of SEQ ID NO: 2, as described in Payne et al., Chem. Rev. 115: 11308-1448.
Beta-glucosidase: The term “beta-glucosidase” means a beta-D-glucoside glucohydrolase (E.C. 3.2.1.21) that catalyzes the hydrolysis of terminal non-reducing beta-D-glucose residues with the release of beta-D-glucose. For purposes of the present invention, beta-glucosidase activity is determined using p-nitrophenyl-beta-D-glucopyranoside as substrate according to the procedure of Venturi et al., 2002 , J. Basic Microbiol. 42: 55-66. One unit of beta-glucosidase is defined as 1.0 μmole of p-nitrophenolate anion produced per minute at 25° C., pH 4.8 from 1 mM p-nitrophenyl-beta-D-glucopyranoside as substrate in 50 mM sodium citrate containing 0.01% TWEEN® 20.
Beta-xylosidase: The term “beta-xylosidase” means a beta-D-xyloside xylohydrolase (E.C. 3.2.1.37) that catalyzes the exo-hydrolysis of short beta (1→4)-xylooligosaccharides to remove successive D-xylose residues from non-reducing termini. For purposes of the present invention, beta-xylosidase activity is determined using 1 mM p-nitrophenyl-beta-D-xyloside as substrate in 100 mM sodium citrate containing 0.01% TWEEN® 20 at pH 5, 40° C. One unit of beta-xylosidase is defined as 1.0 μmole of p-nitrophenolate anion produced per minute at 40° C., pH 5 from 1 mM p-nitrophenyl-beta-D-xyloside as substrate in 100 mM sodium citrate containing 0.01% TWEEN® 20.
Carbohydrate binding module: The term “carbohydrate binding module” means a domain within a carbohydrate-active enzyme that provides carbohydrate-binding activity (Boraston et al., 2004 , Biochem. J. 383: 769-781). A majority of known carbohydrate binding modules (CBMs) are contiguous amino acid sequences with a discrete fold. The carbohydrate binding module (CBM) is typically found either at the N-terminal or at the C-terminal extremity of an enzyme. The term “carbohydrate binding module” is also used interchangedly herein with the term “carbohydrate binding domain”.
Catalytic domain: The term “catalytic domain” means the region of an enzyme containing the catalytic machinery of the enzyme. In one aspect, the catalytic domain is amino acids 1 to 429 of SEQ ID NO: 2. In another aspect, the catalytic domain is amino acids 1 to 437 of SEQ ID NO: 8. In another aspect, the catalytic domain is amino acids 1 to 440 of SEQ ID NO: 10. In another aspect, the catalytic domain is amino acids 1 to 437 of SEQ ID NO: 12. In another aspect, the catalytic domain is amino acids 1 to 437 of SEQ ID NO: 14. In another aspect, the catalytic domain is amino acids 1 to 438 of SEQ ID NO: 16. In another aspect, the catalytic domain is amino acids 1 to 437 of SEQ ID NO: 18. In another aspect, the catalytic domain is amino acids 1 to 430 of SEQ ID NO: 20. In another aspect, the catalytic domain is amino acids 1 to 433 of SEQ ID NO: 22.
Catalytic domain coding sequence: The term “catalytic domain coding sequence” means a polynucleotide that encodes a domain catalyzing cellobiohydrolase activity. In one aspect, the catalytic domain coding sequence is nucleotides 52 to 1469 of SEQ ID NO: 1. In another aspect, the catalytic domain coding sequence is nucleotides 52 to 1389 of SEQ ID NO: 3. In another aspect, the catalytic domain coding sequence is nucleotides 52 to 1389 of SEQ ID NO: 4. In another aspect, the catalytic domain coding sequence is nucleotides 79 to 1389 of SEQ ID NO: 7. In another aspect, the catalytic domain coding sequence is nucleotides 52 to 1371 of SEQ ID NO: 9. In another aspect, the catalytic domain coding sequence is nucleotides 55 to 1482 of SEQ ID NO: 11. In another aspect, the catalytic domain coding sequence is nucleotides 76 to 1386 of SEQ ID NO: 13. In another aspect, the catalytic domain is nucleotides 76 to 1386 of SEQ ID NO: 15. In another aspect, the catalytic domain coding sequence is nucleotides 55 to 1504 of SEQ ID NO: 17. In another aspect, the catalytic domain coding sequence is nucleotides 61 to 1350 of SEQ ID NO: 19. In another aspect, the catalytic domain coding sequence is nucleotides 55 to 1353 of SEQ ID NO: 21.
cDNA: The term “cDNA” means a DNA molecule that can be prepared by reverse transcription from a mature, spliced, mRNA molecule obtained from a eukaryotic or prokaryotic cell. cDNA lacks intron sequences that may be present in the corresponding genomic DNA. The initial, primary RNA transcript is a precursor to mRNA that is processed through a series of steps, including splicing, before appearing as mature spliced mRNA.
Cellobiohydrolase: The term “cellobiohydrolase” means a 1,4-beta-D-glucan cellobiohydrolase (E.C. 3.2.1.91 and E.C. 3.2.1.176) that catalyzes the hydrolysis of 1,4-beta-D-glucosidic linkages in cellulose, cellooligosaccharides, or any beta-1,4-linked glucose containing polymer, releasing cellobiose from the reducing end (cellobiohydrolase I) or non-reducing end (cellobiohydrolase II) of the chain (Teeri, 1997 , Trends in Biotechnology 15: 160-167; Teeri et al., 1998 , Biochem. Soc. Trans. 26: 173-178). Cellobiohydrolase activity is determined according to the procedures described by Lever et al., 1972 , Anal. Biochem. 47: 273-279; van Tilbeurgh et al., 1982 , FEBS Letters, 149: 152-156; van Tilbeurgh and Claeyssens, 1985 , FEBS Letters, 187: 283-288; and Tomme et al., 1988 , Eur. J. Biochem. 170: 575-581. In the present invention, cellobiohydrolase activity is preferably determined according to Examples 8 and 9 herein.
Cellulolytic enzyme or cellulase: The term “cellulolytic enzyme” or “cellulase” means one or more (e.g., several) enzymes that hydrolyze a cellulosic material. Such enzymes include endoglucanase(s), cellobiohydrolase(s), beta-glucosidase(s), or combinations thereof. The two basic approaches for measuring cellulolytic enzyme activity include: (1) measuring the total cellulolytic enzyme activity, and (2) measuring the individual cellulolytic enzyme activities (endoglucanases, cellobiohydrolases, and beta-glucosidases) as reviewed in Zhang et al., 2006 , Biotechnology Advances 24: 452-481. Total cellulolytic activity is usually measured using insoluble substrates, including Whatman No 1 filter paper, microcrystalline cellulose, bacterial cellulose, algal cellulose, cotton, pretreated lignocellulose, etc. The most common total cellulolytic activity assay is the filter paper assay using Whatman No 1 filter paper as the substrate. The assay was established by the International Union of Pure and Applied Chemistry (IUPAC) (Ghose, 1987 , Pure Appl. Chem. 59: 257-68).
For purposes of the present invention, cellulolytic enzyme activity is determined by measuring the increase in hydrolysis of a cellulosic material by cellulolytic enzyme(s) under the following conditions: 1-50 mg of cellulolytic enzyme protein/g of cellulose in PCS (or other pretreated cellulosic material) for 3-7 days at a suitable temperature such as 25° C.-80° C., e.g., 30° C., 35° C., 40° C., 45° C., 50° C., 55° C., 60° C., 65° C., or 70° C., and a suitable pH such as 4-9, e.g., 5.0, 5.5, 6.0, 6.5, or 7.0, compared to a control hydrolysis without addition of cellulolytic enzyme protein. Typical conditions are 1 ml reactions, washed or unwashed PCS, 5% insoluble solids (dry weight), 50 mM sodium acetate pH 5, 1 mM MnSO 4 , 50° C., 55° C., or 60° C., 72 hours, sugar analysis by AMINEX® HPX-87H column chromatography (Bio-Rad Laboratories, Inc., Hercules, Calif., USA).
Cellulosic material: The term “cellulosic material” means any material containing cellulose. The predominant polysaccharide in the primary cell wall of biomass is cellulose, the second most abundant is hemicellulose, and the third is pectin. The secondary cell wall, produced after the cell has stopped growing, also contains polysaccharides and is strengthened by polymeric lignin covalently cross-linked to hemicellulose. Cellulose is a homopolymer of anhydrocellobiose and thus a linear beta-(1-4)-D-glucan, while hemicelluloses include a variety of compounds, such as xylans, xyloglucans, arabinoxylans, and mannans in complex branched structures with a spectrum of substituents. Although generally polymorphous, cellulose is found in plant tissue primarily as an insoluble crystalline matrix of parallel glucan chains. Hemicelluloses usually hydrogen bond to cellulose, as well as to other hemicelluloses, which help stabilize the cell wall matrix.
Cellulose is generally found, for example, in the stems, leaves, hulls, husks, and cobs of plants or leaves, branches, and wood of trees. The cellulosic material can be, but is not limited to, agricultural residue, herbaceous material (including energy crops), municipal solid waste, pulp and paper mill residue, waste paper, and wood (including forestry residue) (see, for example, Wiselogel et al., 1995, in Handbook on Bioethanol (Charles E. Wyman, editor), pp. 105-118, Taylor & Francis, Washington D.C.; Wyman, 1994 , Bioresource Technology 50: 3-16; Lynd, 1990 , Applied Biochemistry and Biotechnology 24/25: 695-719; Mosier et al., 1999, Recent Progress in Bioconversion of Lignocellulosics, in Advances in Biochemical Engineering/Biotechnology , T. Scheper, managing editor, Volume 65, pp. 23-40, Springer-Verlag, New York). It is understood herein that the cellulose may be in the form of lignocellulose, a plant cell wall material containing lignin, cellulose, and hemicellulose in a mixed matrix. In one aspect, the cellulosic material is any biomass material. In another aspect, the cellulosic material is lignocellulose, which comprises cellulose, hemicelluloses, and lignin.
In an embodiment, the cellulosic material is agricultural residue, herbaceous material (including energy crops), municipal solid waste, pulp and paper mill residue, waste paper, or wood (including forestry residue).
In another embodiment, the cellulosic material is arundo , bagasse, bamboo, corn cob, corn fiber, corn stover, miscanthus , rice straw, switchgrass, or wheat straw.
In another embodiment, the cellulosic material is aspen, eucalyptus , fir, pine, poplar, spruce, or willow.
In another embodiment, the cellulosic material is algal cellulose, bacterial cellulose, cotton linter, filter paper, microcrystalline cellulose (e.g., AVICEL®), or phosphoric-acid treated cellulose.
In another embodiment, the cellulosic material is an aquatic biomass. As used herein the term “aquatic biomass” means biomass produced in an aquatic environment by a photosynthesis process. The aquatic biomass can be algae, emergent plants, floating-leaf plants, or submerged plants.
The cellulosic material may be used as is or may be subjected to pretreatment, using conventional methods known in the art, as described herein. In a preferred aspect, the cellulosic material is pretreated.
Coding sequence: The term “coding sequence” means a polynucleotide, which directly specifies the amino acid sequence of a variant. The boundaries of the coding sequence are generally determined by an open reading frame, which begins with a start codon such as ATG, GTG or TTG and ends with a stop codon such as TAA, TAG, or TGA. The coding sequence may be a genomic DNA, cDNA, synthetic DNA, or a combination thereof.
Control sequences: The term “control sequences” means nucleic acid sequences necessary for expression of a polynucleotide encoding a variant of the present invention. Each control sequence may be native (i.e., from the same gene) or foreign (i.e., from a different gene) to the polynucleotide encoding the variant or native or foreign to each other. Such control sequences include, but are not limited to, a leader, polyadenylation sequence, propeptide sequence, promoter, signal peptide sequence, and transcription terminator. At a minimum, the control sequences include a promoter, and transcriptional and translational stop signals. The control sequences may be provided with linkers for the purpose of introducing specific restriction sites facilitating ligation of the control sequences with the coding region of the polynucleotide encoding a variant.
Endoglucanase: The term “endoglucanase” means a 4-(1,3;1,4)-beta-D-glucan 4-glucanohydrolase (E.C. 3.2.1.4) that catalyzes endohydrolysis of 1,4-beta-D-glycosidic linkages in cellulose, cellulose derivatives (such as carboxymethyl cellulose and hydroxyethyl cellulose), lichenin, beta-1,4 bonds in mixed beta-1,3-1,4 glucans such as cereal beta-D-glucans or xyloglucans, and other plant material containing cellulosic components. Endoglucanase activity can be determined by measuring reduction in substrate viscosity or increase in reducing ends determined by a reducing sugar assay (Zhang et al., 2006 , Biotechnology Advances 24: 452-481). For purposes of the present invention, endoglucanase activity is determined using carboxymethyl cellulose (CMC) as substrate according to the procedure of Ghose, 1987 , Pure and Appl. Chem. 59: 257-268, at pH 5, 40° C.
Expression: The term “expression” includes any step involved in the production of a variant including, but not limited to, transcription, post-transcriptional modification, translation, post-translational modification, and secretion.
Expression vector: The term “expression vector” means a linear or circular DNA molecule that comprises a polynucleotide encoding a variant and is operably linked to control sequences that provide for its expression.
Family 61 glycoside hydrolase: The term “Family 61 glycoside hydrolase” or “Family GH61” or “GH61” means a polypeptide falling into the glycoside hydrolase Family 61 according to Henrissat, 1991 , Biochem. J. 280: 309-316, and Henrissat, and Bairoch, 1996 , Biochem. J. 316: 695-696. The GH61 polypeptides have recently been classified as lytic polysaccharide monooxygenases (Quinlan et al., 2011 , Proc. Natl. Acad. Sci. USA 208: 15079-15084; Phillips et al., 2011 , ACS Chem. Biol. 6: 1399-1406; Lin et al., 2012 , Structure 20: 1051-1061) and are designated “Auxiliary Activity 9” or “AA9” polypeptides.
Feruloyl esterase: The term “feruloyl esterase” means a 4-hydroxy-3-methoxycinnamoyl-sugar hydrolase (EC 3.1.1.73) that catalyzes the hydrolysis of 4-hydroxy-3-methoxycinnamoyl (feruloyl) groups from esterified sugar, which is usually arabinose in natural biomass substrates, to produce ferulate (4-hydroxy-3-methoxycinnamate). Feruloyl esterase (FAE) is also known as ferulic acid esterase, hydroxycinnamoyl esterase, FAE-III, cinnamoyl ester hydrolase, FAEA, cinnAE, FAE-I, or FAE-II. For purposes of the present invention, feruloyl esterase activity is determined using 0.5 mM p-nitrophenylferulate as substrate in 50 mM sodium acetate pH 5.0. One unit of feruloyl esterase equals the amount of enzyme capable of releasing 1 μmole of p-nitrophenolate anion per minute at pH 5, 25° C.
Fragment: The term “fragment” means a polypeptide having one or more (e.g., several) amino acids absent from the amino and/or carboxyl terminus of a mature polypeptide; wherein the fragment has cellobiohydrolase activity. In one aspect, a fragment contains at least 420 amino acid residues, e.g., at least 445 amino acid residues or at least 470 amino acid residues of the mature polypeptide of SEQ ID NO: 2 or a variant thereof. In another aspect, a fragment contains at least 430 amino acid residues, e.g., at least 455 amino acid residues or at least 480 amino acid residues of the mature polypeptide of SEQ ID NO: 8 or a variant thereof. In another aspect, a fragment contains at least 380 amino acid residues, e.g., at least 400 amino acid residues or at least 420 amino acid residues of the mature polypeptide of SEQ ID NO: 10 or a variant thereof. In another aspect, a fragment contains at least 380 amino acid residues, e.g., at least 400 amino acid residues or at least 420 amino acid residues of the mature polypeptide of SEQ ID NO: 12 or a variant thereof. In another aspect, a fragment contains at least 430 amino acid residues, e.g., at least 455 amino acid residues or at least 480 amino acid residues of the mature polypeptide of SEQ ID NO: 14 or a variant thereof. In another aspect, a fragment contains at least 430 amino acid residues, e.g., at least 455 amino acid residues or at least 480 amino acid residues of the mature polypeptide of SEQ ID NO: 16 or a variant thereof. In another aspect, a fragment contains at least 380 amino acid residues, e.g., at least 400 amino acid residues or at least 420 amino acid residues of the mature polypeptide of SEQ ID NO: 18 or a variant thereof. In another aspect, a fragment contains at least 370 amino acid residues, e.g., at least 390 amino acid residues or at least 410 amino acid residues of the mature polypeptide of SEQ ID NO: 20 or a variant thereof. In another aspect, a fragment contains at least 435 amino acid residues, e.g., at least 460 amino acid residues or at least 485 amino acid residues of the mature polypeptide of SEQ ID NO: 22 or a variant thereof.
Hemicellulolytic enzyme or hemicellulase: The term “hemicellulolytic enzyme” or “hemicellulase” means one or more (e.g., several) enzymes that hydrolyze a hemicellulosic material. See, for example, Shallom and Shoham, 2003 , Current Opinion In Microbiology 6(3): 219-228). Hemicellulases are key components in the degradation of plant biomass. Examples of hemicellulases include, but are not limited to, an acetylmannan esterase, an acetylxylan esterase, an arabinanase, an arabinofuranosidase, a coumaric acid esterase, a feruloyl esterase, a galactosidase, a glucuronidase, a glucuronoyl esterase, a mannanase, a mannosidase, a xylanase, and a xylosidase. The substrates for these enzymes, hemicelluloses, are a heterogeneous group of branched and linear polysaccharides that are bound via hydrogen bonds to the cellulose microfibrils in the plant cell wall, crosslinking them into a robust network. Hemicelluloses are also covalently attached to lignin, forming together with cellulose a highly complex structure. The variable structure and organization of hemicelluloses require the concerted action of many enzymes for its complete degradation. The catalytic modules of hemicellulases are either glycoside hydrolases (GHs) that hydrolyze glycosidic bonds, or carbohydrate esterases (CEs), which hydrolyze ester linkages of acetate or ferulic acid side groups. These catalytic modules, based on homology of their primary sequence, can be assigned into GH and CE families. Some families, with an overall similar fold, can be further grouped into clans, marked alphabetically (e.g., GH-A). A most informative and updated classification of these and other carbohydrate active enzymes is available in the Carbohydrate-Active Enzymes (CAZy) database. Hemicellulolytic enzyme activities can be measured according to Ghose and Bisaria, 1987 , Pure & Appl. Chem. 59: 1739-1752, at a suitable temperature such as 40° C.-80° C., e.g., 50° C., 55° C., 60° C., 65° C., or 70° C., and a suitable pH such as 4-9, e.g., 5.0, 5.5, 6.0, 6.5, or 7.0.
High stringency conditions: The term “high stringency conditions” means for probes of at least 100 nucleotides in length, prehybridization and hybridization at 42° C. in 5× SSPE, 0.3% SDS, 200 micrograms/ml sheared and denatured salmon sperm DNA, and 50% formamide, following standard Southern blotting procedures for 12 to 24 hours. The carrier material is finally washed three times each for 15 minutes using 0.2×SSC, 0.2% SDS at 65° C.
Host cell: The term “host cell” means any cell type that is susceptible to transformation, transfection, transduction, or the like with a nucleic acid construct or expression vector comprising a polynucleotide of the present invention. The term “host cell” encompasses any progeny of a parent cell that is not identical to the parent cell due to mutations that occur during replication.
Improved property: The term “improved property” means a characteristic associated with a variant that is improved compared to the parent. Such an improved property is preferably increased specific performance.
Increased specific performance: The term “increased specific performance” by a variant of the present invention means improved conversion of a cellulosic material to a product, as compared to the same level of conversion by the parent. Increased specific performance is determined per unit protein (e.g., mg protein, or μmole protein). The increased specific performance of the variant relative to the parent can be assessed, for example, under one or more (e.g., several) conditions of pH, temperature, and substrate concentration. In one aspect, the product is glucose. In another aspect, the product is cellobiose. In another aspect, the product is glucose+cellobiose.
In one aspect, the condition is pH. For example, the pH can be any pH in the range of 3 to 7, e.g., 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, or 7.0 (or in between). Any suitable buffer for achieving the desired pH can be used.
In another aspect, the condition is temperature. For example, the temperature can be any temperature in the range of 25° C. to 90° C., e.g., 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, or 90° C. (or in between).
In another aspect, the condition is substrate concentration. Any cellulosic material defined herein can be used as the substrate. In one aspect, the substrate concentration is measured as the dry solids content. The dry solids content is preferably in the range of about 1 to about 50 wt %, e.g., about 5 to about 45 wt %, about 10 to about 40 wt %, or about 20 to about 30 wt %. In another aspect, the substrate concentration is measured as the insoluble glucan content. The insoluble glucan content is preferably in the range of about 2.5 to about 25 wt %, e.g., about 5 to about 20 wt % or about 10 to about 15 wt %.
In another aspect, a combination of two or more (e.g., several) of the above conditions are used to determine the increased specific performance of the variant relative to the parent, such as any temperature in the range of 25° C. to 90° C., e.g., 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, or 90° C. (or in between) at a pH in the range of 3 to 7, e.g., 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, or 7.0 (or in between).
The increased specific performance of the variant relative to the parent can be determined using any enzyme assay known in the art for cellobiohydrolases as described herein. Alternatively, the increased specific performance of the variant relative to the parent can be determined using the assays described in Examples 8 and 9.
In another aspect, the specific performance of the variant is at least 1.01-fold, e.g., at least 1.02-fold, at least 1.03-fold, at least 1.04-fold, at least 1.05-fold, at least 1.06-fold, at least 1.07-fold, at least 1.08-fold, at least 1.09-fold, at least 1.1-fold, at least 1.2-fold, at least 1.3-fold, at least 1.4-fold, at least 1.5-fold, at least 1.6-fold, at least 1.7-fold, at least 1.8-fold, at least 1.9-fold, at least 2-fold, at least 2.1-fold, at least 2.2-fold, at least 2.3-fold, at least 2.4-fold, at least 2.5-fold, at least 5-fold, at least 10-fold, at least 15-fold, at least 20-fold, at least 25-fold, and at least 50-fold higher than the specific performance of the parent.
Isolated: The term “isolated” means a substance in a form or environment that does not occur in nature. Non-limiting examples of isolated substances include (1) any non-naturally occurring substance, (2) any substance including, but not limited to, any enzyme, variant, nucleic acid, protein, peptide or cofactor, that is at least partially removed from one or more or all of the naturally occurring constituents with which it is associated in nature; (3) any substance modified by the hand of man relative to that substance found in nature; or (4) any substance modified by increasing the amount of the substance relative to other components with which it is naturally associated (e.g., recombinant production in a host cell; multiple copies of a gene encoding the substance; and use of a stronger promoter than the promoter naturally associated with the gene encoding the substance).
Low stringency conditions: The term “low stringency conditions” means for probes of at least 100 nucleotides in length, prehybridization and hybridization at 42° C. in 5×SSPE, 0.3% SDS, 200 micrograms/ml sheared and denatured salmon sperm DNA, and 25% formamide, following standard Southern blotting procedures for 12 to 24 hours. The carrier material is finally washed three times each for 15 minutes using 0.2×SSC, 0.2% SDS at 50° C.
Mature polypeptide: The term “mature polypeptide” means a polypeptide in its final form following translation and any post-translational modifications, such as N-terminal processing, C-terminal truncation, glycosylation, phosphorylation, etc. In one aspect, the mature polypeptide is amino acids 1 to 497 of SEQ ID NO: 2 based on the SignalP 3.0 program (Bendtsen et al., 2004 , J. Mol. Biol. 340: 783-795) that predicts amino acids −1 to −17 of SEQ ID NO: 2 are a signal peptide. In another aspect, the mature polypeptide is amino acids 1 to 506 of SEQ ID NO: 8 (P3EX) based on the SignalP 3.0 program that predicts amino acids −1 to −26 of SEQ ID NO: 8 are a signal peptide. In another aspect, the mature polypeptide is amino acids 1 to 440 of SEQ ID NO: 10 (P57J) based on the SignalP 3.0 program that predicts amino acids −1 to −17 of SEQ ID NO: 10 are a signal peptide. In another aspect, the mature polypeptide is amino acids 1 to 437 of SEQ ID NO: 12 (P82PH) based on the SignalP 3.0 program that predicts amino acids −1 to −18 of SEQ ID NO: 12 are a signal peptide. In another aspect, the mature polypeptide is amino acids 1 to 507 of SEQ ID NO: 14 (P23YSY) based on the SignalP 3.0 program that predicts amino acids −1 to −25 of SEQ ID NO: 14 are a signal peptide. In another aspect, the mature polypeptide is amino acids 1 to 507 of SEQ ID NO: 16 (P23YSX) based on the SignalP 3.0 program that predicts amino acids −1 to −25 of SEQ ID NO: 16 are a signal peptide. In another aspect, the mature polypeptide is amino acids 1 to 437 of SEQ ID NO: 18 (P24765) based on the SignalP 3.0 program that predicts amino acids −1 to −18 of SEQ ID NO: 18 are a signal peptide. In another aspect, the mature polypeptide is amino acids 1 to 430 of SEQ ID NO: 20 (P66Z) based on the SignalP 3.0 program that predicts amino acids −1 to −20 of SEQ ID NO: 20 are a signal peptide. In another aspect, the mature polypeptide is amino acids 1 to 511 of SEQ ID NO: 22 (P57G) based on the SignalP 3.0 program that predicts amino acids −1 to −18 of SEQ ID NO: 22 are a signal peptide. It is known in the art that a host cell may produce a mixture of two of more different mature polypeptides (i.e., with a different C-terminal and/or N-terminal amino acid) expressed by the same polynucleotide. It is also known in the art that different host cells may process polypeptides differently, and thus, one host cell expressing a polynucleotide may produce a different mature polypeptide (e.g., having a different C-terminal and/or N-terminal amino acid) as compared to another host cell expressing the same polynucleotide.
Mature polypeptide coding sequence: The term “mature polypeptide coding sequence” means a polynucleotide that encodes a mature polypeptide having cellobiohydrolase activity. In one aspect, the mature polypeptide coding sequence is nucleotides 52 to 1673 of SEQ ID NO: 1 (without the stop codon) based on SignalP 3.0 program (Bendtsen et al., 2004, supra) that predicts nucleotides 1 to 51 of SEQ ID NO: 1 encode a signal peptide. In another aspect, the mature polypeptide coding sequence is nucleotides 52 to 1542 of SEQ ID NO: 3 (without the stop codon) based on SignalP 3.0 program that predicts nucleotides 1 to 51 of SEQ ID NO: 3 encode a signal peptide. In another aspect, the mature polypeptide coding sequence is nucleotides 52 to 1542 of SEQ ID NO: 4 (without the stop codon) based on SignalP 3.0 program that predicts nucleotides 1 to 51 of SEQ ID NO: 4 encode a signal peptide. In another aspect, the mature polypeptide coding sequence is nucleotides 79 to 1596 of SEQ ID NO: 7 (D1R9) (without the stop codon) based on SignalP 3.0 program that predicts nucleotides 1 to 78 of SEQ ID NO: 7 encode a signal peptide. In another aspect, the mature polypeptide coding sequence is nucleotides 52 to 1371 of SEQ ID NO: 9 (D3FQ) (without the stop codon) based on SignalP 3.0 program that predicts nucleotides 1 to 51 of SEQ ID NO: 9 encode a signal peptide. In another aspect, the mature polypeptide coding sequence is nucleotides 55 to 1482 of SEQ ID NO: 11 (D23Y2) (without the stop codon) based on SignalP 3.0 program that predicts nucleotides 1 to 54 of SEQ ID NO: 11 encode a signal peptide. In another aspect, the mature polypeptide coding sequence is nucleotides 76 to 1596 of SEQ ID NO: 13 (D72PP3) (without the stop codon) based on SignalP 3.0 program that predicts nucleotides 1 to 75 of SEQ ID NO: 13 encode a signal peptide. In another aspect, the mature polypeptide coding sequence is nucleotides 76 to 1596 of SEQ ID NO: 15 (D72PP2) (without the stop codon) based on SignalP 3.0 program that predicts nucleotides 1 to 75 of SEQ ID NO: 15 encode a signal peptide. In another aspect, the mature polypeptide coding sequence is nucleotides 55 to 1504 of SEQ ID NO: 17 (D82ACF) (without the stop codon) based on SignalP 3.0 program that predicts nucleotides 1 to 54 of SEQ ID NO: 17 encode a signal peptide. In another aspect, the mature polypeptide coding sequence is nucleotides 61 to 1350 of SEQ ID NO: 19 (D6CT) (without the stop codon) based on SignalP 3.0 program that predicts nucleotides 1 to 60 of SEQ ID NO: 19 encode a signal peptide. In another aspect, the mature polypeptide coding sequence is nucleotides 55 to 1587 of SEQ ID NO: 21 (D3FP) (without the stop codon) based on SignalP 3.0 program that predicts nucleotides 1 to 54 of SEQ ID NO: 21 encode a signal peptide.
Medium stringency conditions: The term “medium stringency conditions” means for probes of at least 100 nucleotides in length, prehybridization and hybridization at 42° C. in 5×SSPE, 0.3% SDS, 200 micrograms/ml sheared and denatured salmon sperm DNA, and 35% formamide, following standard Southern blotting procedures for 12 to 24 hours. The carrier material is finally washed three times each for 15 minutes using 0.2×SSC, 0.2% SDS at 55° C.
Medium-high stringency conditions: The term “medium-high stringency conditions” means for probes of at least 100 nucleotides in length, prehybridization and hybridization at 42° C. in 5×SSPE, 0.3% SDS, 200 micrograms/ml sheared and denatured salmon sperm DNA, and 35% formamide, following standard Southern blotting procedures for 12 to 24 hours. The carrier material is finally washed three times each for 15 minutes using 0.2×SSC, 0.2% SDS at 60° C.
Mutant: The term “mutant” means a polynucleotide encoding a variant.
Nucleic acid construct: The term “nucleic acid construct” means a nucleic acid molecule, either single- or double-stranded, which is isolated from a naturally occurring gene or is modified to contain segments of nucleic acids in a manner that would not otherwise exist in nature or which is synthetic, which comprises one or more control sequences.
Operably linked: The term “operably linked” means a configuration in which a control sequence is placed at an appropriate position relative to the coding sequence of a polynucleotide such that the control sequence directs expression of the coding sequence.
Parent or parent cellobiohydrolase: The term “parent” or “parent cellobiohydrolase” means a polypeptide having cellobiohydrolase activity to which an alteration, i.e., a substitution, insertion, and/or deletion, at one or more (e.g., several) positions, is made to produce an enzyme variant of the present invention. The parent may be a naturally occurring (wild-type) polypeptide or a variant or fragment thereof.
Polypeptide having cellulolytic enhancing activity: The term “polypeptide having cellulolytic enhancing activity” means a GH61 polypeptide or variant thereof that catalyzes the enhancement of the hydrolysis of a cellulosic material by enzyme having cellulolytic activity, i.e., a cellulase. For purposes of the present invention, cellulolytic enhancing activity is determined by measuring the increase in reducing sugars or the increase of the total of cellobiose and glucose from the hydrolysis of a cellulosic material by cellulolytic enzyme under the following conditions: 1-50 mg of total protein/g of cellulose in pretreated corn stover (PCS), wherein total protein is comprised of 50-99.5% w/w cellulolytic enzyme protein and 0.5-50% w/w protein of a GH61 polypeptide or variant thereof for 1-7 days at a suitable temperature, such as 25° C.-80° C., e.g., 30° C., 35° C., 40° C., 45° C., 50° C., 55° C., 60° C., 65° C., or 70° C., and a suitable pH, such as 4-9, e.g., 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, or 8.5, compared to a control hydrolysis with equal total protein loading without cellulolytic enhancing activity (1-50 mg of cellulolytic protein/g of cellulose in PCS) In one aspect, GH61 polypeptide enhancing activity is determined using a mixture of CELLUCLAST® 1.5L (Novozymes A/S, Bagsvaerd, Denmark) in the presence of 2-3% of total protein weight Aspergillus oryzae beta-glucosidase (recombinantly produced in Aspergillus oryzae according to WO 02/095014) or 2-3% of total protein weight Aspergillus fumigatus beta-glucosidase (recombinantly produced in Aspergillus oryzae as described in WO 02/095014) of cellulase protein loading is used as the source of the cellulolytic activity.
Another assay for determining the cellulolytic enhancing activity of a GH61 polypeptide or variant thereof is to incubate the GH61 polypeptide or variant with 0.5% phosphoric acid swollen cellulose (PASO), 100 mM sodium acetate pH 5, 1 mM MnSO 4 , 0.1% gallic acid, 0.025 mg/ml of Aspergillus fumigatus beta-glucosidase, and 0.01% TRITON® X100 (4-(1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol) for 24-96 hours at 40° C. followed by determination of the glucose released from the PASO.
The GH61 polypeptides or variants thereof having cellulolytic enhancing activity enhance the hydrolysis of a cellulosic material catalyzed by enzyme having cellulolytic activity by reducing the amount of cellulolytic enzyme required to reach the same degree of hydrolysis preferably at least 1.01-fold, e.g., at least 1.05-fold, at least 1.10-fold, at least 1.25-fold, at least 1.5-fold, at least 2-fold, at least 3-fold, at least 4-fold, at least 5-fold, at least 10-fold, or at least 20-fold.
Pretreated corn stover: The term “Pretreated Corn Stover” or “PCS” means a cellulosic material derived from corn stover by treatment with heat and dilute sulfuric acid, alkaline pretreatment, neutral pretreatment, or any pretreatment known in the art.
Sequence identity: The relatedness between two amino acid sequences or between two nucleotide sequences is described by the parameter “sequence identity”.
For purposes of the present invention, the sequence identity between two amino acid sequences is determined using the Needleman-Wunsch algorithm (Needleman and Wunsch, 1970 , J. Mol. Biol. 48: 443-453) as implemented in the Needle program of the EMBOSS package (EMBOSS: The European Molecular Biology Open Software Suite, Rice et al., 2000 , Trends Genet. 16: 276-277), preferably version 5.0.0 or later. The parameters used are a gap open penalty of 10, a gap extension penalty of 0.5, and the EBLOSUM62 (EMBOSS version of BLOSUM62) substitution matrix. The output of Needle labeled “longest identity” (obtained using the −nobrief option) is used as the percent identity and is calculated as follows:
(Identical Residues×100)/(Length of Alignment−Total Number of Gaps in Alignment)
For purposes of the present invention, the sequence identity between two deoxyribonucleotide sequences is determined using the Needleman-Wunsch algorithm (Needleman and Wunsch, 1970, supra) as implemented in the Needle program of the EMBOSS package (EMBOSS: The European Molecular Biology Open Software Suite, Rice et al., 2000, supra), preferably version 5.0.0 or later. The parameters used are a gap open penalty of 10, a gap extension penalty of 0.5, and the EDNAFULL (EMBOSS version of NCBI NUC4.4) substitution matrix. The output of Needle labeled “longest identity” (obtained using the −nobrief option) is used as the percent identity and is calculated as follows:
(Identical Deoxyribonucleotides×100)/(Length of Alignment−Total Number of Gaps in Alignment)
Subsequence: The term “subsequence” means a polynucleotide having one or more (e.g., several) nucleotides absent from the 5′ and/or 3′ end of a mature polypeptide coding sequence; wherein the subsequence encodes a fragment having cellobiohydrolase activity. In one aspect, a subsequence contains at least 1400 nucleotides, e.g., at least 1475 nucleotides or at least 1550 nucleotides of the mature polypeptide coding sequence of SEQ ID NO: 1 or a mutant thereof. In another aspect, a subsequence contains at least 1260 nucleotides, e.g., at least 1335 nucleotides or at least 1410 nucleotides of the mature polypeptide coding sequence of SEQ ID NO: 3 or a mutant thereof. In another aspect, a subsequence contains at least 1260 nucleotides, e.g., at least 1335 nucleotides or at least 1410 nucleotides of the mature polypeptide coding sequence of SEQ ID NO: 4 or a mutant thereof. In another aspect, a fragment contains at least 1290 nucleotides, e.g., at least 1365 nucleotides or at least 1440 nucleotides of the mature polypeptide of SEQ ID NO: 7 or a mutant thereof. In another aspect, a fragment contains at least 1140 nucleotides, e.g., at least 1200 nucleotides or at least 1260 nucleotides of the mature polypeptide of SEQ ID NO: 9 or a mutant thereof. In another aspect, a fragment contains at least 1140 nucleotides, e.g., at least 1200 nucleotides or at least 1260 nucleotides of the mature polypeptide of SEQ ID NO: 11 or a mutant thereof. In another aspect, a fragment contains at least 1290 nucleotides, e.g., at least 1365 nucleotides or at least 1440 nucleotides of the mature polypeptide of SEQ ID NO: 13 or a mutant thereof. In another aspect, a fragment contains at least 1290 nucleotides, e.g., at least 1365 nucleotides or at least 1440 nucleotides of the mature polypeptide of SEQ ID NO: 15 or a mutant thereof. In another aspect, a fragment contains at least 1140 nucleotides, e.g., at least 1200 nucleotides or at least 1260 nucleotides of the mature polypeptide of SEQ ID NO: 17 or a mutant thereof. In another aspect, a fragment contains at least 1110 nucleotides, e.g., at least 1170 nucleotides or at least 1230 nucleotides of the mature polypeptide of SEQ ID NO: 19 or a mutant thereof. In another aspect, a fragment contains at least 1305 nucleotides, e.g., at least 1380 nucleotides or at least 1455 nucleotides of the mature polypeptide of SEQ ID NO: 21 or a mutant thereof.
Variant: The term “variant” means a polypeptide having cellobiohydrolase activity comprising an alteration, i.e., a substitution, insertion, and/or deletion, at one or more (e.g., several) positions. A substitution means replacement of the amino acid occupying a position with a different amino acid; a deletion means removal of the amino acid occupying a position; and an insertion means adding an amino acid adjacent to and immediately following the amino acid occupying a position. The variants of the present invention have a specific performance which is at least 1.01-fold higher than the specific performance of the parent.
Very high stringency conditions: The term “very high stringency conditions” means for probes of at least 100 nucleotides in length, prehybridization and hybridization at 42° C. in 5×SSPE, 0.3% SDS, 200 micrograms/ml sheared and denatured salmon sperm DNA, and 50% formamide, following standard Southern blotting procedures for 12 to 24 hours. The carrier material is finally washed three times each for 15 minutes using 0.2×SSC, 0.2% SDS at 70° C.
Very low stringency conditions: The term “very low stringency conditions” means for probes of at least 100 nucleotides in length, prehybridization and hybridization at 42° C. in 5×SSPE, 0.3% SDS, 200 micrograms/ml sheared and denatured salmon sperm DNA, and 25% formamide, following standard Southern blotting procedures for 12 to 24 hours. The carrier material is finally washed three times each for 15 minutes using 0.2×SSC, 0.2% SDS at 45° C.
Wild-type cellobiohydrolase: The term “wild-type” cellobiohydrolase means a cellobiohydrolase naturally produced by a microorganism, such as a bacterium, yeast, or filamentous fungus found in nature.
Xylan-containing material: The term “xylan-containing material” means any material comprising a plant cell wall polysaccharide containing a backbone of beta-(1-4)-linked xylose residues. Xylans of terrestrial plants are heteropolymers possessing a beta-(1-4)-D-xylopyranose backbone, which is branched by short carbohydrate chains. They comprise D-glucuronic acid or its 4-O-methyl ether, L-arabinose, and/or various oligosaccharides, composed of D-xylose, L-arabinose, D- or L-galactose, and D-glucose. Xylan-type polysaccharides can be divided into homoxylans and heteroxylans, which include glucuronoxylans, (arabino)glucuronoxylans, (glucurono)arabinoxylans, arabinoxylans, and complex heteroxylans. See, for example, Ebringerova et al., 2005 , Adv. Polym. Sci. 186: 1-67.
In the processes of the present invention, any material containing xylan may be used. In a preferred aspect, the xylan-containing material is lignocellulose.
Xylan degrading activity or xylanolytic activity: The term “xylan degrading activity” or “xylanolytic activity” means a biological activity that hydrolyzes xylan-containing material. The two basic approaches for measuring xylanolytic activity include: (1) measuring the total xylanolytic activity, and (2) measuring the individual xylanolytic activities (e.g., endoxylanases, beta-xylosidases, arabinofuranosidases, alpha-glucuronidases, acetylxylan esterases, feruloyl esterases, and alpha-glucuronyl esterases). Recent progress in assays of xylanolytic enzymes was summarized in several publications including Biely and Puchard, 2006 , Journal of the Science of Food and Agriculture 86(11): 1636-1647; Spanikova and Biely, 2006 , FEBS Letters 580(19): 4597-4601; Herrimann et al., 1997 , Biochemical Journal 321: 375-381.
Total xylan degrading activity can be measured by determining the reducing sugars formed from various types of xylan, including, for example, oat spelt, beechwood, and larchwood xylans, or by photometric determination of dyed xylan fragments released from various covalently dyed xylans. A common total xylanolytic activity assay is based on production of reducing sugars from polymeric 4-O-methyl glucuronoxylan as described in Bailey et al., 1992, Interlaboratory testing of methods for assay of xylanase activity, Journal of Biotechnology 23(3): 257-270. Xylanase activity can also be determined with 0.2% AZCL-arabinoxylan as substrate in 0.01% TRITON® X-100 and 200 mM sodium phosphate pH 6 at 37° C. One unit of xylanase activity is defined as 1.0 μmole of azurine produced per minute at 37° C., pH 6 from 0.2% AZCL-arabinoxylan as substrate in 200 mM sodium phosphate pH 6.
For purposes of the present invention, xylan degrading activity is determined by measuring the increase in hydrolysis of birchwood xylan (Sigma Chemical Co., Inc., St. Louis, Mo., USA) by xylan-degrading enzyme(s) under the following typical conditions: 1 ml reactions, 5 mg/ml substrate (total solids), 5 mg of xylanolytic protein/g of substrate, 50 mM sodium acetate pH 5, 50° C., 24 hours, sugar analysis using p-hydroxybenzoic acid hydrazide (PHBAH) assay as described by Lever, 1972 , Anal. Biochem 47: 273-279.
Xylanase: The term “xylanase” means a 1,4-beta-D-xylan-xylohydrolase (E.C. 3.2.1.8) that catalyzes the endohydrolysis of 1,4-beta-D-xylosidic linkages in xylans. For purposes of the present invention, xylanase activity is determined with 0.2% AZCL-arabinoxylan as substrate in 0.01% TRITON® X-100 and 200 mM sodium phosphate pH 6 at 37° C. One unit of xylanase activity is defined as 1.0 μmole of azurine produced per minute at 37° C., pH 6 from 0.2% AZCL-arabinoxylan as substrate in 200 mM sodium phosphate pH 6.
Conventions for Designation of Variants
For purposes of the present invention, the sequence of SEQ ID NO: 2 is used to determine the corresponding amino acid residue in another cellobiohydrolase. The amino acid sequence of another cellobiohydrolase is aligned with SEQ ID NO: 2, and based on the alignment, the amino acid position number corresponding to any amino acid residue in SEQ ID NO: 2 is determined using the Needleman-Wunsch algorithm (Needleman and Wunsch, 1970 , J. Mol. Biol. 48: 443-453) as implemented in the Needle program of the EMBOSS package (EMBOSS: The European Molecular Biology Open Software Suite, Rice et al., 2000 , Trends Genet. 16: 276-277), preferably version 5.0.0 or later. The parameters used are a gap open penalty of 10, a gap extension penalty of 0.5, and the EBLOSUM62 (EMBOSS version of BLOSUM62) substitution matrix. Numbering of the amino acid positions is based on the full-length polypeptide (e.g., including the signal peptide) of SEQ ID NO: 2 wherein position −17 is the first amino acid of the signal peptide (i.e., Met) and position 1 is Gln of SEQ ID NO: 2. For example, the position corresponding to position 197 of the Trichoderma reesei cellobiohydrolase I (SEQ ID NO: 2) is position 194 of the Rasamsonia emersonii cellobiohydrolase I, and position 200 of the Trichoderma reesei cellobiohydrolase I is position 197 of the Rasamsonia emersonii cellobiohydrolase I.
Identification of the corresponding amino acid residue in another cellobiohydrolase can be determined by an alignment of multiple polypeptide sequences using several computer programs including, but not limited to, MUSCLE (multiple sequence comparison by log-expectation; version 3.5 or later; Edgar, 2004 , Nucleic Acids Research 32: 1792-1797), MAFFT (version 6.857 or later; Katoh and Kuma, 2002 , Nucleic Acids Research 30: 3059-3066; Katoh et al., 2005 , Nucleic Acids Research 33: 511-518; Katoh and Toh, 2007 , Bioinformatics 23: 372-374; Katoh et al., 2009 , Methods in Molecular Biology 537: 39-64; Katoh and Toh, 2010 , Bioinformatics 26: 1899-1900), and EMBOSS EMMA employing ClustalW (1.83 or later; Thompson et al., 1994 , Nucleic Acids Research 22: 4673-4680), using their respective default parameters.
When another cellobiohydrolase has diverged from the sequence of SEQ ID NO: 2 such that traditional sequence-based comparison fails to detect their relationship (Lindahl and Elofsson, 2000 , J. Mol. Biol. 295: 613-615), other pairwise sequence comparison algorithms can be used. Greater sensitivity in sequence-based searching can be attained using search programs that utilize probabilistic representations of polypeptide families (profiles) to search databases. For example, the PSI-BLAST program generates profiles through an iterative database search process and is capable of detecting remote homologs (Atschul et al., 1997 , Nucleic Acids Res. 25: 3389-3402). Even greater sensitivity can be achieved if the family or superfamily for the polypeptide has one or more representatives in the protein structure databases. Programs such as GenTHREADER (Jones, 1999 , J. Mol. Biol. 287: 797-815; McGuffin and Jones, 2003 , Bioinformatics 19: 874-881) utilize information from a variety of sources (PSI-BLAST, secondary structure prediction, structural alignment profiles, and solvation potentials) as input to a neural network that predicts the structural fold for a query sequence. Similarly, the method of Gough et al., 2000 , J. Mol. Biol. 313: 903-919, can be used to align a sequence of unknown structure with the superfamily models present in the SCOP database. These alignments can in turn be used to generate homology models for the polypeptide, and such models can be assessed for accuracy using a variety of tools developed for that purpose.
For proteins of known structure, several tools and resources are available for retrieving and generating structural alignments. For example the SCOP superfamilies of proteins have been structurally aligned, and those alignments are accessible and downloadable. Two or more protein structures can be aligned using a variety of algorithms such as the distance alignment matrix (Holm and Sander, 1998 , Proteins 33: 88-96) or combinatorial extension (Shindyalov and Bourne, 1998 , Protein Engineering 11: 739-747), and implementation of these algorithms can additionally be utilized to query structure databases with a structure of interest in order to discover possible structural homologs (e.g., Holm and Park, 2000 , Bioinformatics 16: 566-567).
In describing the cellobiohydrolase variants of the present invention, the nomenclature described below is adapted for ease of reference. The accepted IUPAC single letter or three letter amino acid abbreviation is employed.
Substitutions.
For an amino acid substitution, the following nomenclature is used: Original amino acid, position, substituted amino acid. Accordingly, the substitution of threonine at position 226 with alanine is designated as “Thr226Ala” or “T226A”. Multiple mutations are separated by addition marks (“+”), e.g., “Gly205Arg+Ser411Phe” or “G205R+S411F”, representing substitutions at positions 205 and 411 of glycine (G) with arginine (R) and serine (S) with phenylalanine (F), respectively.
Deletions.
For an amino acid deletion, the following nomenclature is used: Original amino acid, position, *. Accordingly, the deletion of glycine at position 195 is designated as “Gly195*” or “G195*”. Multiple deletions are separated by addition marks (“+”), e.g., “Gly195*+Ser411*” or “G195*+S411*”.
Insertions.
For an amino acid insertion, the following nomenclature is used: Original amino acid, position, original amino acid, inserted amino acid. Accordingly the insertion of lysine after glycine at position 195 is designated “Gly195GlyLys” or “G195GK”. An insertion of multiple amino acids is designated [Original amino acid, position, original amino acid, inserted amino acid #1, inserted amino acid #2; etc.]. For example, the insertion of lysine and alanine after glycine at position 195 is indicated as “Gly195GlyLysAla” or “G195GKA”.
In such cases the inserted amino acid residue(s) are numbered by the addition of lower case letters to the position number of the amino acid residue preceding the inserted amino acid residue(s). In the above example, the sequence would thus be:
Parent:
Variant:
195
195 195a 195b
G
G-K-A
Multiple Alterations.
Variants comprising multiple alterations are separated by addition marks (“+”), e.g., “Arg170Tyr+Gly195Glu” or “R170Y+G195E” representing a substitution of arginine and glycine at positions 170 and 195 with tyrosine and glutamic acid, respectively.
Different Alterations.
Where different alterations can be introduced at a position, the different alterations are separated by a comma, e.g., “Arg170Tyr,Glu” represents a substitution of arginine at position 170 with tyrosine or glutamic acid. Thus, “Tyr167Gly,Ala+Arg170Gly,Ala” designates the following variants:
“Tyr167Gly+Arg170Gly”, “Tyr167Gly+Arg170Ala”, “Tyr167Ala+Arg170Gly”, and “Tyr167Ala+Arg170Ala”.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to cellobiohydrolase variants, comprising deletions at two or more consecutive positions of the B2-loop, wherein the variants have cellobiohydrolase activity.
The present invention also relates to isolated cellobiohydrolase variants, comprising a deletion at one or more positions corresponding to positions 195, 196, 197, 198, and 199 of SEQ ID NO: 2, and wherein the variants have cellobiohydrolase activity.
Variants
In an embodiment, the variant has a sequence identity of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100%, to the amino acid sequence of the parent cellobiohydrolase or the mature polypeptide thereof.
In another embodiment, the variant has at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100%, sequence identity to the mature polypeptide of SEQ ID NO: 2.
In another embodiment, the variant has at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100%, sequence identity to the mature polypeptide of SEQ ID NO: 8.
In another embodiment, the variant has at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100%, sequence identity to the mature polypeptide of SEQ ID NO: 10.
In another embodiment, the variant has at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100%, sequence identity to the mature polypeptide of SEQ ID NO: 12.
In another embodiment, the variant has at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100%, sequence identity to the mature polypeptide of SEQ ID NO: 14.
In another embodiment, the variant has at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100%, sequence identity to the mature polypeptide of SEQ ID NO: 16.
In another embodiment, the variant has at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100%, sequence identity to the mature polypeptide of SEQ ID NO: 18.
In another embodiment, the variant has at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100%, sequence identity to the mature polypeptide of SEQ ID NO: 20.
In another embodiment, the variant has at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100%, sequence identity to the mature polypeptide of SEQ ID NO: 22.
In one aspect, the number of alterations (e.g., substitutions and/or deletions) in the variants of the present invention is 1-4, e.g., 1, 2, 3, or 4 alterations. In another aspect, the number of substitutions and/or deletions in the variants of the present invention is 1-3, e.g., 1, 2, or 3 substitutions. In another aspect, the number of deletions in the variants of the present invention is 1 deletion.
In one aspect, a variant comprises or consists of deletions at two or more consecutive positions of the B2-loop. In one embodiment, the variant comprises deletions at positions corresponding to positions 194 and 195 of SEQ ID NO: 2 (e.g., P194*+S195*). In another embodiment, the variant comprises deletions at positions corresponding to positions 195 and 196 of SEQ ID NO: 2 (e.g., S195*+S196*, or S195*+A196*). In another embodiment, the variant comprises deletions at positions corresponding to positions 196 and 197 of SEQ ID NO: 2 (e.g., S196*+N197*, or A196*+N197*). In another embodiment, the variant comprises deletions at positions corresponding to positions 197 and 198 of SEQ ID NO: 2 (e.g., N197*+N198*, N197*+D198*). In another embodiment, the variant comprises deletions at positions corresponding to positions 198 and 199 of SEQ ID NO: 2 (e.g., N198*+A199*, D198*+A199*, or D198*+P199*). In another embodiment, the variant comprises deletions at positions corresponding to positions 199 and 200 of SEQ ID NO: 2 (e.g., A199*+N200*, or P199*+N200*). In another embodiment, the variant comprises deletions at positions corresponding to positions 200 and 201 of SEQ ID NO: 2 (e.g., N200*+T201*, N200*+A201*, or N200*+S201*).
In another aspect, a variant comprises or consists of deletions at three or more consecutive positions of the B2-loop (e.g., deletions at positions corresponding to positions 194*+195*+196*, 195*+196*+197*, 196*+197*+198*, 197*+198*+199*, 198*+199*+200*, or 199*+200*+201* of SEQ ID NO: 2).
In another aspect, a variant comprises or consists of deletions at four or more consecutive positions of the B2-loop (e.g., deletions at positions corresponding to positions 194*+195*+196*+197*, 195*+196*+197*+198*, 196*+197*+198*+199*, 197*+198*+199*+200*, or 198*+199*+200*+201* of SEQ ID NO: 2).
In another aspect, a variant comprises or consists of deletions at five or more consecutive positions of the B2-loop (e.g., deletions at positions corresponding to positions 194*+195*+196*+197*+198*, 195*+196*+197*+198*+199*, 196*+197*+198*+199*+200*, or 197*+198*+199*+200*+201* of SEQ ID NO: 2).
In another aspect, a variant comprises or consists of deletions at six or more consecutive positions of the B2-loop. (e.g., deletions at positions corresponding to positions 194*+195*+196*+197*+198*+199*, 195*+196*+197*+198*+199*+200*, or 196*+197*+198*+199*+200*+201* of SEQ ID NO: 2).
In another aspect, a variant comprises or consists of deletions at seven or more consecutive positions of the B2-loop (e.g., deletions at positions corresponding to positions 194*+195*+196*+197*+198*+199*+200*, or 195*+196*+197*+198*+199*+200*+201* of SEQ ID NO: 2).
In one aspect, a variant comprises or consists of deletions at eight consecutive positions of the B2-loop (e.g., deletions at positions corresponding to positions 194*+195*+196*+197*+198*+199*+200*+201* of SEQ ID NO: 2).
In another aspect, a variant comprises a deletion at one or more (e.g., several) positions corresponding to positions 195, 196, 197, and 198 of SEQ ID NO: 2.
In one aspect, the variant comprises or consists of a deletion at one position corresponding to positions 195, 196, 197, and 198 of SEQ ID NO: 2. In one embodiment, the variant comprises or consists of a deletion at a position corresponding to position 195 of SEQ ID NO: 2. In one embodiment, the deletion is an S195* deletion. In another embodiment, the variant comprises or consists of a deletion at a position corresponding to position 196 of SEQ ID NO: 2. In one embodiment, the deletion is an S196* deletion. In another embodiment, the variant comprises or consists of a deletion at a position corresponding to position 197 of SEQ ID NO: 2. In one embodiment, the deletion is an N197* deletion. In another embodiment, the variant comprises or consists of a deletion at a position corresponding to position 198 of SEQ ID NO: 2. In one embodiment, the deletion is an N198* deletion. In any of these embodiments, the variant may further comprise a substitution at any position corresponding positions 197, 198, and 200, and/or a deletion at a position corresponding to position 199 of SEQ ID NO: 2, as described infra.
In another aspect, a variant comprises or consists of a deletion at two positions corresponding to any of positions 195, 196, 197, and 198 of SEQ ID NO: 2. In one embodiment, the variant comprises or consists of deletions at positions corresponding to positions 195 and 196 of SEQ ID NO: 2. In one embodiment, the deletions are S195*+S196* deletions. In one embodiment, the variant comprises or consists of deletions at positions corresponding to positions 195 and 197 of SEQ ID NO: 2. In one embodiment, the deletions are S195*+N197* deletions. In one embodiment, the variant comprises or consists of deletions at positions corresponding to positions 195 and 198 of SEQ ID NO: 2. In one embodiment, the deletions are S195*+N198* deletions. In one embodiment, the variant comprises or consists of deletions at positions corresponding to positions 196 and 197 of SEQ ID NO: 2. In one embodiment, the deletions are S196*+N197* deletions. In one embodiment, the variant comprises or consists of deletions at positions corresponding to positions 196 and 198 of SEQ ID NO: 2. In one embodiment, the deletions are S196*+N198* deletions. In one embodiment, the variant comprises or consists of deletions at positions corresponding to positions 197 and 198 of SEQ ID NO: 2. In one embodiment, the deletions are N197*+N198* deletions. In any of these embodiments, the variant may further comprise a substitution at any position corresponding positions 197, 198, and 200, and/or a deletion at a position corresponding to position 199 of SEQ ID NO: 2, as described infra.
In another aspect, a variant comprises a deletion at positions corresponding to positions 196, 197, and 198 of SEQ ID NO: 2. In one embodiment, the deletions are S196*+N197*+N198* deletions. In one embodiment, the variant may further comprise a substitution at a position corresponding position 200, and/or a deletion at a position corresponding to position 199 of SEQ ID NO: 2, as described infra.
In another aspect, a variant comprises a deletion at each position corresponding to positions 195, 196, 197, and 198 of SEQ ID NO: 2. In one embodiment, the deletions are S195*+S196*+N197*+N198* deletions. In one embodiment, the variant may further comprise a substitution at a position corresponding position 200, and/or a deletion at a position corresponding to position 199 of SEQ ID NO: 2, as described infra.
In one embodiment, the variant comprises or consists of amino acids 1-434 of SEQ ID NO: 78. In another embodiment, the variant comprises or consists of amino acids 1-495 of SEQ ID NO: 80. In another embodiment, the variant comprises or consists of amino acids 1-495 of SEQ ID NO: 82.
The variants may further comprise one or more additional alterations, e.g., substitutions, insertions, or deletions at one or more (e.g., several) other positions, such as a substitution, a deletion, and/or an insertion at one or more (e.g., several) other positions disclosed in PCT/US2014/022068, WO 2011/050037, WO 2005/028636, WO 2005/001065, WO 2004/016760, and U.S. Pat. No. 7,375,197, which are incorporated herein in their entireties.
For example, in one aspect, the variant comprises an alteration at one or more positions corresponding to positions 197, 198, 199, and 200 of SEQ ID NO: 2, wherein the alteration at the one or more positions corresponding to positions 197, 198, and 200 is a substitution and the alteration at the position corresponding to position 199 is a deletion. In another aspect, a variant comprises an alteration at two positions corresponding to any of positions 197, 198, 199, and 200 of SEQ ID NO: 2, wherein the alteration at the one or more positions corresponding to positions 197, 198, and 200 is a substitution and the alteration at the position corresponding to position 199 is a deletion. In another aspect, a variant comprises an alteration at three positions corresponding to any of positions 197, 198, 199, and 200 of SEQ ID NO: 2, wherein the alteration at the one or more positions corresponding to positions 197, 198, and 200 is a substitution and the alteration at the position corresponding to position 199 is a deletion. In another aspect, a variant comprises a substitution at each position corresponding to positions 197, 198, and 200 and a deletion at a position corresponding to position 199.
In another aspect, the variant comprises a substitution at a position corresponding to position 197. In another aspect, the amino acid at a position corresponding to position 197 is substituted with Ala, Arg, Asn, Asp, Cys, Gln, Glu, Gly, His, Ile, Leu, Lys, Met, Phe, Pro, Ser, Thr, Trp, Tyr, or Val, preferably with Ala. In another aspect, the variant comprises the substitution N197A of SEQ ID NO: 2.
In another aspect, the variant comprises a substitution at a position corresponding to position 198. In another aspect, the amino acid at a position corresponding to position 198 is substituted with Ala, Arg, Asn, Asp, Cys, Gln, Glu, Gly, His, Ile, Leu, Lys, Met, Phe, Pro, Ser, Thr, Trp, Tyr, or Val, preferably with Ala. In another aspect, the variant comprises the substitution N198A of SEQ ID NO: 2.
In another aspect, the variant comprises a deletion at a position corresponding to position 199. In another aspect, the amino acid at a position corresponding to position 199 is Ala, Arg, Asn, Asp, Cys, Gln, Glu, Gly, His, Ile, Leu, Lys, Met, Phe, Pro, Ser, Thr, Trp, Tyr, or Val, preferably Ala. In another aspect, the variant comprises the deletion A199* of SEQ ID NO: 2.
In another aspect, the variant comprises a substitution at a position corresponding to position 200. In another aspect, the amino acid at a position corresponding to position 200 is substituted with Ala, Arg, Asn, Asp, Cys, Gln, Glu, Gly, His, Ile, Leu, Lys, Met, Phe, Pro, Ser, Thr, Trp, Tyr, or Val, preferably with Ala, Gly, or Trp. In another aspect, the variant comprises the substitution N200A,G,W of SEQ ID NO: 2.
In another aspect, the variant comprises an alteration at positions corresponding to positions 197 and 198, such as those described above.
In another aspect, the variant comprises alterations at positions corresponding to positions 197 and 199, such as those described above.
In another aspect, the variant comprises alterations at positions corresponding to positions 197 and 200, such as those described above.
In another aspect, the variant comprises alterations at positions corresponding to positions 198 and 199, such as those described above.
In another aspect, the variant comprises alterations at positions corresponding to positions 198 and 200, such as those described above.
In another aspect, the variant comprises alterations at positions corresponding to positions 199 and 200, such as those described above.
In another aspect, the variant comprises alterations at positions corresponding to positions 197, 198, and 199, such as those described above.
In another aspect, the variant comprises alterations at positions corresponding to positions 197, 198, and 200, such as those described above.
In another aspect, the variant comprises alterations at positions corresponding to positions 197, 199, and 200, such as those described above.
In another aspect, the variant comprises alterations at positions corresponding to positions 198, 199, and 200, such as those described above.
In another aspect, the variant comprises alterations at positions corresponding to positions 197, 198, 199, and 200, such as those described above.
In another aspect, the variant comprises one or more alterations selected from the group consisting of N197A, N198A, A199*, and N200A,G,W.
In another aspect, the variant comprises the alterations N197A+N198A of SEQ ID NO: 2.
In another aspect, the variant comprises the alterations N197A+A199* of SEQ ID NO: 2.
In another aspect, the variant comprises the alterations N197A+N200A,G,W of SEQ ID NO: 2.
In another aspect, the variant comprises the alterations N198A+A199* of SEQ ID NO: 2.
In another aspect, the variant comprises the alterations N198A+N200A,G,W of SEQ ID NO: 2.
In another aspect, the variant comprises the alterations A199*+N200A,G,W of SEQ ID NO: 2.
In another aspect, the variant comprises the alterations N197A+N198A+A199* of SEQ ID NO: 2.
In another aspect, the variant comprises the alterations N197A+N198A+N200A,G,W of SEQ ID NO: 2.
In another aspect, the variant comprises the alterations N197A+A199*+N200A,G,W of SEQ ID NO: 2.
In another aspect, the variant comprises the alterations N198A+A199*+N200A,G,W of SEQ ID NO: 2.
In another aspect, the variant comprises the alterations N197A+N198A+A199*+N200A,G,W of SEQ ID NO: 2.
The variants may further comprise one or more additional alterations, e.g., substitutions, insertions, or deletions at one or more (e.g., several) other positions.
The amino acid changes may be of a minor nature, that is conservative amino acid substitutions or insertions that do not significantly affect the folding and/or activity of the protein; small deletions, typically of 1-30 amino acids; small amino- or carboxyl-terminal extensions, such as an amino-terminal methionine residue; a small linker peptide of up to 20-25 residues; or a small extension that facilitates purification by changing net charge or another function, such as a poly-histidine tract, an antigenic epitope or a binding domain.
Examples of conservative substitutions are within the groups of basic amino acids (arginine, lysine and histidine), acidic amino acids (glutamic acid and aspartic acid), polar amino acids (glutamine and asparagine), hydrophobic amino acids (leucine, isoleucine and valine), aromatic amino acids (phenylalanine, tryptophan and tyrosine), and small amino acids (glycine, alanine, serine, threonine and methionine). Amino acid substitutions that do not generally alter specific activity are known in the art and are described, for example, by H. Neurath and R. L. Hill, 1979, In, The Proteins , Academic Press, New York. Common substitutions are Ala/Ser, Val/Ile, Asp/Glu, Thr/Ser, Ala/Gly, Ala/Thr, Ser/Asn, Ala/Val, Ser/Gly, Tyr/Phe, Ala/Pro, Lys/Arg, Asp/Asn, Leu/Ile, Leu/Val, Ala/Glu, and Asp/Gly.
Alternatively, the amino acid changes are of such a nature that the physico-chemical properties of the polypeptides are altered. For example, amino acid changes may improve the thermal stability of the polypeptide, alter the substrate specificity, change the pH optimum, and the like.
The variants may even further comprise one or more (e.g., several) substitutions at positions corresponding to positions disclosed in WO 2011/050037, WO 2011/050037, WO 2005/02863, WO 2005/001065, WO 2004/016760, and U.S. Pat. No. 7,375,197, which are incorporated herein in their entireties.
Essential amino acids in a polypeptide can be identified according to procedures known in the art, such as site-directed mutagenesis or alanine-scanning mutagenesis (Cunningham and Wells, 1989 , Science 244: 1081-1085). In the latter technique, single alanine mutations are introduced at every residue in the molecule, and the resultant mutant molecules are tested for cellobiohydrolase activity to identify amino acid residues that are critical to the activity of the molecule. See also, Hilton et al., 1996 , J. Biol. Chem. 271: 4699-4708. The active site of the enzyme or other biological interaction can also be determined by physical analysis of structure, as determined by such techniques as nuclear magnetic resonance, crystallography, electron diffraction, or photoaffinity labeling, in conjunction with mutation of putative contact site amino acids. See, for example, de Vos et al., 1992 , Science 255: 306-312; Smith et al., 1992 , J. Mol. Biol. 224: 899-904; Wlodaver et al., 1992 , FEBS Lett. 309: 59-64. The identity of essential amino acids can also be inferred from an alignment with a related polypeptide.
The variants may consist of 370 to 507 amino acids, e.g., 370 to 380, 380 to 390, 390 to 400, 400 to 410, 410 to 420, 420 to 430, 430 to 440, 450 to 460, 460 to 470, 470 to 480, 480 to 490, 490 to 500, or 500 to 507 amino acids.
In each of the embodiments described above, a variant of the present invention may be a hybrid polypeptide (chimera) in which a region of the variant is replaced with a region of another polypeptide. In one aspect, the region is a carbohydrate binding domain. The carbohydrate binding domain of a variant may be replaced with another (heterologous) carbohydrate binding domain.
In each of the embodiments described above, a variant of the present invention may be a fusion polypeptide or cleavable fusion polypeptide in which another polypeptide is fused at the N-terminus or the C-terminus of the variant. In one aspect, the other polypeptide is a carbohydrate binding domain. The catalytic domain of a variant of the present invention without a carbohydrate binding domain may be fused to a carbohydrate binding domain. A fusion polypeptide is produced by fusing a polynucleotide encoding another polypeptide to a polynucleotide encoding a variant of the present invention. Techniques for producing fusion polypeptides are known in the art, and include ligating the coding sequences encoding the polypeptides so that they are in frame and expression of the fusion polypeptide is under control of the same promoter(s) and terminator. Fusion polypeptides may also be constructed using intein technology in which fusion polypeptides are created post-translationally (Cooper et al., 1993 , EMBO J. 12: 2575-2583; Dawson et al., 1994 , Science 266: 776-779).
A fusion polypeptide can further comprise a cleavage site between the two polypeptides. Upon secretion of the fusion protein, the site is cleaved releasing the two polypeptides. Examples of cleavage sites include, but are not limited to, the sites disclosed in Martin et al., 2003 , J. Ind. Microbiol. Biotechnol. 3: 568-576; Svetina et al., 2000 , J. Biotechnol. 76: 245-251; Rasmussen-Wilson et al., 1997 , Appl. Environ. Microbiol. 63: 3488-3493; Ward et al., 1995 , Biotechnology 13: 498-503; and Contreras et al., 1991 , Biotechnology 9: 378-381; Eaton et al., 1986 , Biochemistry 25: 505-512; Collins-Racie et al., 1995 , Biotechnology 13: 982-987; Carter et al., 1989 , Proteins: Structure, Function, and Genetics 6: 240-248; and Stevens, 2003 , Drug Discovery World 4: 35-48.
In one embodiment, the variant is a hybrid or chimeric polypeptide in which the carbohydrate binding domain of the variant is replaced with a different carbohydrate binding domain. In another embodiment, the variant is a fusion protein in which a heterologous carbohydrate binding domain is fused to the variant. In one aspect, the carbohydrate binding domain is fused to the N-terminus of the variant. In another aspect, the carbohydrate binding domain is fused to the C-terminus of the variant. In another aspect, the fusion protein variant comprises or consists of SEQ ID NO: 78 or the mature polypeptide thereof. SEQ ID NO: 78 is encoded by SEQ ID NO: 77.
In an embodiment, the variant has increased specific performance compared to the parent enzyme.
Parent Cellobiohydrolases
The parent cellobiohydrolase may be any cellobiohydrolase I.
In one embodiment, the parent cellobiohydrolase may be (a) a polypeptide having at least 60% sequence identity to the mature polypeptide of SEQ ID NO: 2; (b) a polypeptide encoded by a polynucleotide that hybridizes under low stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, or SEQ ID NO: 4; or the full-length complement thereof; or (c) a polypeptide encoded by a polynucleotide having at least 60% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, or SEQ ID NO: 4.
In another embodiment, the parent cellobiohydrolase may also be (a) a polypeptide having at least 60% sequence identity to the mature polypeptide of SEQ ID NO: 8; (b) a polypeptide encoded by a polynucleotide that hybridizes under low stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 7; or the full-length complement thereof; or (c) a polypeptide encoded by a polynucleotide having at least 60% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 7.
In another embodiment, the parent cellobiohydrolase may also be (a) a polypeptide having at least 60% sequence identity to the mature polypeptide of SEQ ID NO: 10; (b) a polypeptide encoded by a polynucleotide that hybridizes under low stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 9 or the full-length complement thereof; or (c) a polypeptide encoded by a polynucleotide having at least 60% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 9.
In another embodiment, the parent cellobiohydrolase may also be (a) a polypeptide having at least 60% sequence identity to the mature polypeptide of SEQ ID NO: 12; (b) a polypeptide encoded by a polynucleotide that hybridizes under low stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 11 or the full-length complement thereof; or (c) a polypeptide encoded by a polynucleotide having at least 60% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 11.
In another embodiment, the parent cellobiohydrolase may also be (a) a polypeptide having at least 60% sequence identity to the mature polypeptide of SEQ ID NO: 14; (b) a polypeptide encoded by a polynucleotide that hybridizes under low stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 13 or the full-length complement thereof; or (c) a polypeptide encoded by a polynucleotide having at least 60% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 13.
In another embodiment, the parent cellobiohydrolase may also be (a) a polypeptide having at least 60% sequence identity to the mature polypeptide of SEQ ID NO: 16; (b) a polypeptide encoded by a polynucleotide that hybridizes under low stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 15 or the full-length complement thereof; or (c) a polypeptide encoded by a polynucleotide having at least 60% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 15.
In another embodiment, the parent cellobiohydrolase may also be (a) a polypeptide having at least 60% sequence identity to the mature polypeptide of SEQ ID NO: 18; (b) a polypeptide encoded by a polynucleotide that hybridizes under low stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 17 or the full-length complement thereof; or (c) a polypeptide encoded by a polynucleotide having at least 60% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 17.
In another embodiment, the parent cellobiohydrolase may also be (a) a polypeptide having at least 60% sequence identity to the mature polypeptide of SEQ ID NO: 20; (b) a polypeptide encoded by a polynucleotide that hybridizes under low stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 19 or the full-length complement thereof; or (c) a polypeptide encoded by a polynucleotide having at least 60% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 19.
In another embodiment, the parent cellobiohydrolase may also be (a) a polypeptide having at least 60% sequence identity to the mature polypeptide of SEQ ID NO: 22; (b) a polypeptide encoded by a polynucleotide that hybridizes under low stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 21 or the full-length complement thereof; or (c) a polypeptide encoded by a polynucleotide having at least 60% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 21.
In one aspect, the parent has a sequence identity to the mature polypeptide of SEQ ID NO: 2 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%, which have cellobiohydrolase activity. In another aspect, the amino acid sequence of the parent differs by up to 10 amino acids, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, from the mature polypeptide of SEQ ID NO: 2.
In another aspect, the parent has a sequence identity to the mature polypeptide of SEQ ID NO: 8 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%, which have cellobiohydrolase activity. In another aspect, the amino acid sequence of the parent differs by up to 10 amino acids, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, from the mature polypeptide of SEQ ID NO: 8.
In another aspect, the parent has a sequence identity to the mature polypeptide of SEQ ID NO: 10 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%, which have cellobiohydrolase activity. In another aspect, the amino acid sequence of the parent differs by up to 10 amino acids, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, from the mature polypeptide of SEQ ID NO: 10.
In another aspect, the parent has a sequence identity to the mature polypeptide of SEQ ID NO: 12 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%, which have cellobiohydrolase activity. In another aspect, the amino acid sequence of the parent differs by up to 10 amino acids, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, from the mature polypeptide of SEQ ID NO: 12.
In another aspect, the parent has a sequence identity to the mature polypeptide of SEQ ID NO: 14 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%, which have cellobiohydrolase activity. In another aspect, the amino acid sequence of the parent differs by up to 10 amino acids, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, from the mature polypeptide of SEQ ID NO: 14.
In another aspect, the parent has a sequence identity to the mature polypeptide of SEQ ID NO: 16 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%, which have cellobiohydrolase activity. In another aspect, the amino acid sequence of the parent differs by up to 10 amino acids, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, from the mature polypeptide of SEQ ID NO: 16.
In another aspect, the parent has a sequence identity to the mature polypeptide of SEQ ID NO: 18 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%, which have cellobiohydrolase activity. In another aspect, the amino acid sequence of the parent differs by up to 10 amino acids, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, from the mature polypeptide of SEQ ID NO: 18.
In another aspect, the parent has a sequence identity to the mature polypeptide of SEQ ID NO: 20 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%, which have cellobiohydrolase activity. In another aspect, the amino acid sequence of the parent differs by up to 10 amino acids, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, from the mature polypeptide of SEQ ID NO: 20.
In another aspect, the parent has a sequence identity to the mature polypeptide of SEQ ID NO: 22 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%, which have cellobiohydrolase activity. In another aspect, the amino acid sequence of the parent differs by up to 10 amino acids, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, from the mature polypeptide of SEQ ID NO: 22.
In another aspect, the parent comprises or consists of the amino acid sequence of SEQ ID NO: 2. In another aspect, the parent comprises or consists of the mature polypeptide of SEQ ID NO: 2. In another aspect, the parent comprises or consists of amino acids 1 to 497 of SEQ ID NO: 2.
In another aspect, the parent comprises or consists of the amino acid sequence of SEQ ID NO: 8. In another aspect, the parent comprises or consists of the mature polypeptide of SEQ ID NO: 8. In another aspect, the parent comprises or consists of amino acids 1 to 506 of SEQ ID NO: 8.
In another aspect, the parent comprises or consists of the amino acid sequence of SEQ ID NO: 10. In another aspect, the parent comprises or consists of the mature polypeptide of SEQ ID NO: 10. In another aspect, the parent comprises or consists of amino acids 1 to 437 of SEQ ID NO: 10.
In another aspect, the parent comprises or consists of the amino acid sequence of SEQ ID NO: 12. In another aspect, the parent comprises or consists of the mature polypeptide of SEQ ID NO: 12. In another aspect, the parent comprises or consists of amino acids 1 to 437 of SEQ ID NO: 12.
In another aspect, the parent comprises or consists of the amino acid sequence of SEQ ID NO: 14. In another aspect, the parent comprises or consists of the mature polypeptide of SEQ ID NO: 14. In another aspect, the parent comprises or consists of amino acids 1 to 507 of SEQ ID NO: 14.
In another aspect, the parent comprises or consists of the amino acid sequence of SEQ ID NO: 16. In another aspect, the parent comprises or consists of the mature polypeptide of SEQ ID NO: 16. In another aspect, the parent comprises or consists of amino acids 1 to 507 of SEQ ID NO: 16.
In another aspect, the parent comprises or consists of the amino acid sequence of SEQ ID NO: 18. In another aspect, the parent comprises or consists of the mature polypeptide of SEQ ID NO: 18. In another aspect, the parent comprises or consists of amino acids 1 to 437 of SEQ ID NO: 18.
In another aspect, the parent comprises or consists of the amino acid sequence of SEQ ID NO: 20. In another aspect, the parent comprises or consists of the mature polypeptide of SEQ ID NO: 20. In another aspect, the parent comprises or consists of amino acids 1 to 430 of SEQ ID NO: 20.
In another aspect, the parent comprises or consists of the amino acid sequence of SEQ ID NO: 22. In another aspect, the parent comprises or consists of the mature polypeptide of SEQ ID NO: 22. In another aspect, the parent comprises or consists of amino acids 1 to 511 of SEQ ID NO: 22.
In another aspect, the parent is a fragment of the mature polypeptide of SEQ ID NO: 2 containing at least 420 amino acid residues, e.g., at least 445 amino acid residues or at least 470 amino acid residues.
In another aspect, the parent is a fragment of the mature polypeptide of SEQ ID NO: 8 containing at 430 amino acid residues, e.g., at least 455 amino acid residues or at least 480 amino acid residues.
In another aspect, the parent is a fragment of the mature polypeptide of SEQ ID NO: 10 containing at least 380 amino acid residues, e.g., at least 400 amino acid residues or at least 420 amino acid residues.
In another aspect, the parent is a fragment of the mature polypeptide of SEQ ID NO: 12 containing at least 380 amino acid residues, e.g., at least 400 amino acid residues or at least 420 amino acid residues.
In another aspect, the parent is a fragment of the mature polypeptide of SEQ ID NO: 14 containing at least 430 amino acid residues, e.g., at least 455 amino acid residues or at least 480 amino acid residues.
In another aspect, the parent is a fragment of the mature polypeptide of SEQ ID NO: 16 containing at least 430 amino acid residues, e.g., at least 455 amino acid residues or at least 480 amino acid residues.
In another aspect, the parent is a fragment of the mature polypeptide of SEQ ID NO: 18 containing at least 380 amino acid residues, e.g., at least 400 amino acid residues or at least 420 amino acid residues.
In another aspect, the parent is a fragment of the mature polypeptide of SEQ ID NO: 20 containing at least 370 amino acid residues, e.g., at least 390 amino acid residues or at least 410 amino acid residues.
In another aspect, the parent is a fragment of the mature polypeptide of SEQ ID NO: 22 containing at least 435 amino acid residues, e.g., at least 460 amino acid residues or at least 485 amino acid residues.
In another aspect, the parent is encoded by a polynucleotide that hybridizes under very low stringency conditions, low stringency conditions, medium stringency conditions, medium-high stringency conditions, high stringency conditions, or very high stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, or SEQ ID NO: 4; or the full-length complement thereof (Sambrook et al., 1989 , Molecular Cloning, A Laboratory Manual, 2d edition, Cold Spring Harbor, New York).
In another aspect, the parent is encoded by a polynucleotide that hybridizes under low stringency conditions, medium stringency conditions, medium-high stringency conditions, high stringency conditions, or very high stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 7; or the full-length complement thereof (Sambrook et al., 1989, supra).
In another aspect, the parent is encoded by a polynucleotide that hybridizes under low stringency conditions, medium stringency conditions, medium-high stringency conditions, high stringency conditions, or very high stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 9; or the full-length complement thereof (Sambrook et al., 1989, supra).
In another aspect, the parent is encoded by a polynucleotide that hybridizes under low stringency conditions, medium stringency conditions, medium-high stringency conditions, high stringency conditions, or very high stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 11; or the full-length complement thereof (Sambrook et al., 1989, supra).
In another aspect, the parent is encoded by a polynucleotide that hybridizes under low stringency conditions, medium stringency conditions, medium-high stringency conditions, high stringency conditions, or very high stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 13; or the full-length complement thereof (Sambrook et al., 1989, supra).
In another aspect, the parent is encoded by a polynucleotide that hybridizes under low stringency conditions, medium stringency conditions, medium-high stringency conditions, high stringency conditions, or very high stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 15; or the full-length complement thereof (Sambrook et al., 1989, supra).
In another aspect, the parent is encoded by a polynucleotide that hybridizes under low stringency conditions, medium stringency conditions, medium-high stringency conditions, high stringency conditions, or very high stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 17; or the full-length complement thereof (Sambrook et al., 1989, supra).
In another aspect, the parent is encoded by a polynucleotide that hybridizes under low stringency conditions, medium stringency conditions, medium-high stringency conditions, high stringency conditions, or very high stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 19; or the full-length complement thereof (Sambrook et al., 1989, supra).
In another aspect, the parent is encoded by a polynucleotide that hybridizes under low stringency conditions, medium stringency conditions, medium-high stringency conditions, high stringency conditions, or very high stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 21; or the full-length complement thereof (Sambrook et al., 1989, supra).
The polynucleotide of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, or SEQ ID NO: 21, or a subsequence thereof, as well as the polypeptide of SEQ ID NO: 2, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 14, SEQ ID NO: 16, SEQ ID NO: 18, SEQ ID NO: 20, or SEQ ID NO: 22, or a fragment thereof, may be used to design nucleic acid probes to identify and clone DNA encoding a parent from strains of different genera or species according to methods well known in the art. In particular, such probes can be used for hybridization with the genomic DNA or cDNA of a cell of interest, following standard Southern blotting procedures, in order to identify and isolate the corresponding gene therein. Such probes can be considerably shorter than the entire sequence, but should be at least 15, e.g., at least 25, at least 35, or at least 70 nucleotides in length. Preferably, the nucleic acid probe is at least 100 nucleotides in length, e.g., at least 200 nucleotides, at least 300 nucleotides, at least 400 nucleotides, at least 500 nucleotides, at least 600 nucleotides, at least 700 nucleotides, at least 800 nucleotides, or at least 900 nucleotides in length. Both DNA and RNA probes can be used. The probes are typically labeled for detecting the corresponding gene (for example, with 32 P, 3 H, 35 S, biotin, or avidin). Such probes are encompassed by the present invention.
A genomic DNA or cDNA library prepared from such other strains may be screened for DNA that hybridizes with the probes described above and encodes a parent. Genomic or other DNA from such other strains may be separated by agarose or polyacrylamide gel electrophoresis, or other separation techniques. DNA from the libraries or the separated DNA may be transferred to and immobilized on nitrocellulose or other suitable carrier material. In order to identify a clone or DNA that hybridizes with SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, or SEQ ID NO: 21, or a subsequence thereof, the carrier material is used in a Southern blot.
For purposes of the present invention, hybridization indicates that the polynucleotide hybridizes to a labeled nucleic acid probe corresponding to (i) SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, or SEQ ID NO: 21; (ii) the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, or SEQ ID NO: 21; (iii) the full-length complement thereof; or (iv) a subsequence thereof; under very low to very high stringency conditions. Molecules to which the nucleic acid probe hybridizes under these conditions can be detected using, for example, X-ray film or any other detection means known in the art.
In one aspect, the nucleic acid probe is the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, or SEQ ID NO: 21. In another aspect, the nucleic acid probe is nucleotides 52 to 1673 of SEQ ID NO: 1, nucleotides 52 to 1542 of SEQ ID NO: 3, nucleotides 52 to 1542 of SEQ ID NO: 4, nucleotides 79 to 1596 of SEQ ID NO: 7, nucleotides 52 to 1371 of SEQ ID NO: 9, nucleotides 55 to 1482 of SEQ ID NO: 11, nucleotides 76 to 1596 of SEQ ID NO: 13, nucleotides 76 to 1596 of SEQ ID NO: 15, nucleotides 55 to 1504 of SEQ ID NO: 17, nucleotides 61 to 1350 of SEQ ID NO: 19, or nucleotides 55 to 1587 of SEQ ID NO: 21. In another aspect, the nucleic acid probe is a polynucleotide that encodes the polypeptide of SEQ ID NO: 2, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 14, SEQ ID NO: 16, SEQ ID NO: 18, SEQ ID NO: 20, or SEQ ID NO: 22; the mature polypeptide thereof; or a fragment thereof. In another aspect, the nucleic acid probe is SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, or SEQ ID NO: 21.
In another aspect, the parent is encoded by a polynucleotide having a sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, or SEQ ID NO: 4 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
In another aspect, the parent is encoded by a polynucleotide having a sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 7 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
In another aspect, the parent is encoded by a polynucleotide having a sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 9 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
In another aspect, the parent is encoded by a polynucleotide having a sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 11 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
In another aspect, the parent is encoded by a polynucleotide having a sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 13 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
In another aspect, the parent is encoded by a polynucleotide having a sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 15 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
In another aspect, the parent is encoded by a polynucleotide having a sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 17 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
In another aspect, the parent is encoded by a polynucleotide having a sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 19 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
In another aspect, the parent is encoded by a polynucleotide having a sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 21 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
In another embodiment, the parent is an allelic variant of the mature polypeptide of SEQ ID NO: 2, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 14, SEQ ID NO: 16, SEQ ID NO: 18, SEQ ID NO: 20, or SEQ ID NO: 22.
The parent may also be a hybrid or chimeric polypeptide in which a region of parent is replaced with a region of another polypeptide. In one aspect, the region is a carbohydrate binding domain. The carbohydrate binding domain of a parent may be replaced with another (heterologous) carbohydrate binding domain.
The parent may also be a fusion polypeptide or cleavable fusion polypeptide in which another polypeptide is fused at the N-terminus or the C-terminus of the parent. In one aspect, the other polypeptide is a carbohydrate binding domain. The catalytic domain of a parent without a carbohydrate binding domain may be fused to a carbohydrate binding domain. A fusion polypeptide is produced by fusing a polynucleotide encoding another polypeptide to a polynucleotide encoding a parent. Techniques for producing fusion polypeptides are described supra. A fusion polypeptide can further comprise a cleavage site between the two polypeptides as described supra.
In one embodiment, the parent is a hybrid polypeptide in which the carbohydrate binding domain of the parent is replaced with a different carbohydrate binding domain. In another embodiment, the parent is a fusion protein in which a heterologous carbohydrate binding domain is fused to the parent without a carbohydrate binding domain. In one aspect, the carbohydrate binding domain is fused to the N-terminus of the parent. In another aspect, the carbohydrate binding domain is fused to the C-terminus of the parent. In another aspect, the fusion protein comprises or consists of SEQ ID NO: 73 or the mature polypeptide thereof. The polynucleotide of SEQ ID NO: 72 encodes the polypeptide of SEQ ID NO: 73.
The parent may be obtained from microorganisms of any genus. For purposes of the present invention, the term “obtained from” as used herein in connection with a given source shall mean that the parent encoded by a polynucleotide is produced by the source or by a strain in which the polynucleotide from the source has been inserted. In one aspect, the parent is secreted extracellularly.
The parent may be a filamentous fungal cellobiohydrolase. For example, the parent may be a filamentous fungal cellobiohydrolase such as an Aspergillus, Chaetomium, Chrysosporium, Myceliophthora, Penicillium, Talaromyces, Thermoascus , or Trichoderma cellobiohydrolase.
In one aspect, the parent is an Aspergillus aculeatus, Aspergillus awamori, Aspergillus foetidus, Aspergillus fumigatus, Aspergillus japonicus, Aspergillus nidulans, Aspergillus niger, Aspergillus oryzae, Chaetomium thermophilum, Chrysosporium inops, Chrysosporium keratinophilum, Chrysosporium lucknowense, Chrysosporium merdarium, Chrysosporium pannicola, Chrysosporium queenslandicum, Chrysosporium tropicum, Chrysosporium zonatum, Myceliophthora thermophila, Penicillium emersonii, Penicillium funiculosum, Penicillium purpurogenum, Talaromyces byssochlamydoides, Talaromyces emersonii, Talaromyces leycettanus, Trichoderma harzianum, Trichoderma koningii, Trichoderma longibrachiaturn, Trichoderma reesei , or Trichoderma viride cellobiohydrolase.
In another aspect, the parent is a Trichoderma reesei cellobiohydrolase, e.g., the cellobiohydrolase of SEQ ID NO: 2 or the mature polypeptide thereof.
In another aspect, the parent is an Aspergillus fumigatus cellobiohydrolase, e.g., the cellobiohydrolase of SEQ ID NO: 8 or the mature polypeptide thereof.
In another aspect, the parent is a Thermoascus aurantiacus cellobiohydrolase, e.g., the cellobiohydrolase of SEQ ID NO: 10 or the mature polypeptide thereof.
In another aspect, the parent is a Penicillium emersonii ( Rasamsonia emersonii ) cellobiohydrolase, e.g., the cellobiohydrolase of SEQ ID NO: 12 or the mature polypeptide thereof.
In another aspect, the parent is a Talaromyces leycettanus cellobiohydrolase, e.g., the cellobiohydrolase of SEQ ID NO: 14 or the mature polypeptide thereof.
In another aspect, the parent is another Talaromyces leycettanus cellobiohydrolase, e.g., the cellobiohydrolase of SEQ ID NO: 16 or the mature polypeptide thereof. In another aspect, the parent is a Talaromyces byssochlamydoides cellobiohydrolase, e.g., the cellobiohydrolase of SEQ ID NO: 18 or the mature polypeptide thereof.
In another aspect, the parent is another Myceliophthora thermophila cellobiohydrolase, e.g., the cellobiohydrolase of SEQ ID NO: 20 or the mature polypeptide thereof.
In another aspect, the parent is another Chaetomium thermophilum cellobiohydrolase, e.g., the cellobiohydrolase of SEQ ID NO: 22 or the mature polypeptide thereof.
It will be understood that for the aforementioned species, the invention encompasses both the perfect and imperfect states, and other taxonomic equivalents, e.g., anamorphs, regardless of the species name by which they are known. Those skilled in the art will readily recognize the identity of appropriate equivalents.
Strains of these species are readily accessible to the public in a number of culture collections, such as the American Type Culture Collection (ATCC), Deutsche Sammlung von Mikroorganismen and Zellkulturen GmbH (DSMZ), Centraalbureau Voor Schimmelcultures (CBS), and Agricultural Research Service Patent Culture Collection, Northern Regional Research Center (NRRL).
The parent may be identified and obtained from other sources including microorganisms isolated from nature (e.g., soil, composts, water, etc.) or DNA samples obtained directly from natural materials (e.g., soil, composts, water, etc.) using the above-mentioned probes. Techniques for isolating microorganisms and DNA directly from natural habitats are well known in the art. A polynucleotide encoding a parent may then be obtained by similarly screening a genomic DNA or cDNA library of another microorganism or mixed DNA sample. Once a polynucleotide encoding a parent has been detected with the probe(s), the polynucleotide can be isolated or cloned by utilizing techniques that are known to those of ordinary skill in the art (see, e.g., Sambrook et al., 1989, supra).
Preparation of Variants
The present invention also relates to methods for obtaining a cellobiohydrolase variant, comprising: (a) introducing into a parent cellobiohydrolase deletions at two or more consecutive positions of the B2-loop, wherein the variant has cellobiohydrolase activity; and optionally (b) recovering the variant.
The present invention also relates to methods for obtaining a cellobiohydrolase variant, comprising: (a) introducing into a parent cellobiohydrolase a deletion at one or more positions corresponding to positions 195, 196, 197, and 198 of SEQ ID NO: 2, wherein the variant has cellobiohydrolase activity; and optionally (b) recovering the variant.
The variants can be prepared using any mutagenesis procedure known in the art, such as site-directed mutagenesis, synthetic gene construction, semi-synthetic gene construction, random mutagenesis, shuffling, etc.
Site-directed mutagenesis is a technique in which one or more (e.g., several) mutations are introduced at one or more defined sites in a polynucleotide encoding the parent. Any site-directed mutagenesis procedure can be used in the present invention. There are many commercial kits available that can be used to prepare variants.
Site-directed mutagenesis can be accomplished in vitro by PCR involving the use of oligonucleotide primers containing the desired mutation. Site-directed mutagenesis can also be performed in vitro by cassette mutagenesis involving the cleavage by a restriction enzyme at a site in the plasmid comprising a polynucleotide encoding the parent and subsequent ligation of an oligonucleotide containing the mutation in the polynucleotide. Usually the restriction enzyme that digests the plasmid and the oligonucleotide is the same, permitting sticky ends of the plasmid and the insert to ligate to one another. See, e.g., Scherer and Davis, 1979 , Proc. Natl. Acad. Sci. USA 76: 4949-4955; and Barton et al., 1990 , Nucleic Acids Res. 18: 7349-4966.
Site-directed mutagenesis can also be accomplished in vivo by methods known in the art. See, e.g., U.S. Patent Application Publication No. 2004/0171154; Storici et al., 2001 , Nature Biotechnol. 19: 773-776; Kren et al., 1998 , Nat. Med. 4: 285-290; and Calissano and Macino, 1996 , Fungal Genet. Newslett. 43: 15-16.
Site-saturation mutagenesis systematically replaces a polypeptide coding sequence with sequences encoding all 19 amino acids at one or more (e.g., several) specific positions (Parikh and Matsumura, 2005 , J. Mol. Biol. 352: 621-628).
Synthetic gene construction entails in vitro synthesis of a designed polynucleotide molecule to encode a polypeptide of interest. Gene synthesis can be performed utilizing a number of techniques, such as the multiplex microchip-based technology described by Tian et al. (2004 , Nature 432: 1050-1054) and similar technologies wherein oligonucleotides are synthesized and assembled upon photo-programmable microfluidic chips.
Single or multiple amino acid substitutions, deletions, and/or insertions can be made and tested using known methods of mutagenesis, recombination, and/or shuffling, followed by a relevant screening procedure, such as those disclosed by Reidhaar-Olson and Sauer, 1988 , Science 241: 53-57; Bowie and Sauer, 1989 , Proc. Natl. Acad. Sci. USA 86: 2152-2156; WO 95/17413; or WO 95/22625. Other methods that can be used include error-prone PCR, phage display (e.g., Lowman et al., 1991 , Biochemistry 30: 10832-10837; U.S. Pat. No. 5,223,409; WO 92/06204) and region-directed mutagenesis (Derbyshire et al., 1986 , Gene 46: 145; Ner et al., 1988 , DNA 7: 127).
Mutagenesis/shuffling methods can be combined with high-throughput, automated screening methods to detect activity of cloned, mutagenized polypeptides expressed by host cells (Ness et al., 1999 , Nature Biotechnology 17: 893-896). Mutagenized DNA molecules that encode active polypeptides can be recovered from the host cells and rapidly sequenced using standard methods in the art. These methods allow the rapid determination of the importance of individual amino acid residues in a polypeptide.
Semi-synthetic gene construction is accomplished by combining aspects of synthetic gene construction, and/or site-directed mutagenesis, and/or random mutagenesis, and/or shuffling. Semi-synthetic construction is typified by a process utilizing polynucleotide fragments that are synthesized, in combination with PCR techniques. Defined regions of genes may thus be synthesized de novo, while other regions may be amplified using site-specific mutagenic primers, while yet other regions may be subjected to error-prone PCR or non-error prone PCR amplification. Polynucleotide subsequences may then be shuffled.
Polynucleotides
The present invention also relates to isolated polynucleotides encoding a variant of the present invention.
Nucleic Acid Constructs
The present invention also relates to nucleic acid constructs comprising a polynucleotide encoding a variant of the present invention operably linked to one or more control sequences that direct the expression of the coding sequence in a suitable host cell under conditions compatible with the control sequences.
The polynucleotide may be manipulated in a variety of ways to provide for expression of a variant. Manipulation of the polynucleotide prior to its insertion into a vector may be desirable or necessary depending on the expression vector. The techniques for modifying polynucleotides utilizing recombinant DNA methods are well known in the art.
The control sequence may be a promoter, a polynucleotide recognized by a host cell for expression of a polynucleotide encoding a variant of the present invention. The promoter contains transcriptional control sequences that mediate the expression of the variant. The promoter may be any polynucleotide that shows transcriptional activity in the host cell including mutant, truncated, and hybrid promoters, and may be obtained from genes encoding extracellular or intracellular polypeptides either homologous or heterologous to the host cell.
Examples of suitable promoters for directing transcription of the nucleic acid constructs of the present invention in a bacterial host cell are the promoters obtained from the Bacillus amyloliquefaciens alpha-amylase gene (amyQ), Bacillus licheniformis alpha-amylase gene (amyL), Bacillus licheniformis penicillinase gene (penP), Bacillus stearothermophilus maltogenic amylase gene (amyM), Bacillus subtilis levansucrase gene (sacB), Bacillus subtilis xylA and xylB genes, Bacillus thuringiensis cryIIIA gene (Agaisse and Lereclus, 1994 , Molecular Microbiology 13: 97-107), E. coli lac operon, E. coli trc promoter (Egon et al., 1988 , Gene 69: 301-315), Streptomyces coelicolor agarase gene (dagA), and prokaryotic beta-lactamase gene (Villa-Kamaroff et al., 1978 , Proc. Natl. Acad. Sci. USA 75: 3727-3731), as well as the tac promoter (DeBoer et al., 1983 , Proc. Natl. Acad. Sci. USA 80: 21-25). Further promoters are described in “Useful proteins from recombinant bacteria” in Gilbert et al., 1980 , Scientific American 242: 74-94; and in Sambrook et al., 1989, supra. Examples of tandem promoters are disclosed in WO 99/43835.
Examples of suitable promoters for directing transcription of the nucleic acid constructs of the present invention in a filamentous fungal host cell are promoters obtained from the genes for Aspergillus nidulans acetamidase, Aspergillus niger neutral alpha-amylase, Aspergillus niger acid stable alpha-amylase, Aspergillus niger or Aspergillus awamori glucoamylase (glaA), Aspergillus oryzae TAKA amylase, Aspergillus oryzae alkaline protease, Aspergillus oryzae triose phosphate isomerase, Fusarium oxysporum trypsin-like protease (WO 96/00787), Fusarium venenatum amyloglucosidase (WO 00/56900), Fusarium venenatum Daria (WO 00/56900), Fusarium venenatum Quinn (WO 00/56900), Rhizomucor miehei lipase, Rhizomucor miehei aspartic proteinase, Trichoderma reesei beta-glucosidase, Trichoderma reesei cellobiohydrolase I, Trichoderma reesei cellobiohydrolase II, Trichoderma reesei endoglucanase I, Trichoderma reesei endoglucanase II, Trichoderma reesei endoglucanase III, Trichoderma reesei endoglucanase V, Trichoderma reesei xylanase I, Trichoderma reesei xylanase II, Trichoderma reesei xylanase III, Trichoderma reesei beta-xylosidase, and Trichoderma reesei translation elongation factor, as well as the NA2-tpi promoter (a modified promoter from an Aspergillus neutral alpha-amylase gene in which the untranslated leader has been replaced by an untranslated leader from an Aspergillus triose phosphate isomerase gene; non-limiting examples include modified promoters from an Aspergillus niger neutral alpha-amylase gene in which the untranslated leader has been replaced by an untranslated leader from an Aspergillus nidulans or Aspergillus oryzae triose phosphate isomerase gene); and mutant, truncated, and hybrid promoters thereof. Other promoters are described in U.S. Pat. No. 6,011,147.
In a yeast host, useful promoters are obtained from the genes for Saccharomyces cerevisiae enolase (ENO-1), Saccharomyces cerevisiae galactokinase (GAL1), Saccharomyces cerevisiae alcohol dehydrogenase/glyceraldehyde-3-phosphate dehydrogenase (ADH1, ADH2/GAP), Saccharomyces cerevisiae triose phosphate isomerase (TPI), Saccharomyces cerevisiae metallothionein (CUP1), and Saccharomyces cerevisiae 3-phosphoglycerate kinase. Other useful promoters for yeast host cells are described by Romanos et al., 1992 , Yeast 8: 423-488.
The control sequence may also be a transcription terminator, which is recognized by a host cell to terminate transcription. The terminator is operably linked to the 3′-terminus of the polynucleotide encoding the variant. Any terminator that is functional in the host cell may be used in the present invention.
Preferred terminators for bacterial host cells are obtained from the genes for Bacillus clausii alkaline protease (aprH), Bacillus licheniformis alpha-amylase (amyL), and Escherichia coli ribosomal RNA (rrnB).
Preferred terminators for filamentous fungal host cells are obtained from the genes for Aspergillus nidulans acetamidase, Aspergillus nidulans anthranilate synthase, Aspergillus niger glucoamylase, Aspergillus niger alpha-glucosidase, Aspergillus oryzae TAKA amylase, Fusarium oxysporum trypsin-like protease, Trichoderma reesei beta-glucosidase, Trichoderma reesei cellobiohydrolase I, Trichoderma reesei cellobiohydrolase II, Trichoderma reesei endoglucanase I, Trichoderma reesei endoglucanase II, Trichoderma reesei endoglucanase III, Trichoderma reesei endoglucanase V, Trichoderma reesei xylanase I, Trichoderma reesei xylanase II, Trichoderma reesei xylanase III, Trichoderma reesei beta-xylosidase, and Trichoderma reesei translation elongation factor.
Preferred terminators for yeast host cells are obtained from the genes for Saccharomyces cerevisiae enolase, Saccharomyces cerevisiae cytochrome C (CYC1), and Saccharomyces cerevisiae glyceraldehyde-3-phosphate dehydrogenase. Other useful terminators for yeast host cells are described by Romanos et al., 1992, supra.
The control sequence may also be an mRNA stabilizer region downstream of a promoter and upstream of the coding sequence of a gene which increases expression of the gene.
Examples of suitable mRNA stabilizer regions are obtained from a Bacillus thuringiensis cryIIIA gene (WO 94/25612) and a Bacillus subtilis SP82 gene (Hue et al., 1995 , Journal of Bacteriology 177: 3465-3471).
The control sequence may also be a leader, a nontranslated region of an mRNA that is important for translation by the host cell. The leader is operably linked to the 5′-terminus of the polynucleotide encoding the variant. Any leader that is functional in the host cell may be used.
Preferred leaders for filamentous fungal host cells are obtained from the genes for Aspergillus oryzae TAKA amylase and Aspergillus nidulans triose phosphate isomerase.
Suitable leaders for yeast host cells are obtained from the genes for Saccharomyces cerevisiae enolase (ENO-1), Saccharomyces cerevisiae 3-phosphoglycerate kinase, Saccharomyces cerevisiae alpha-factor, and Saccharomyces cerevisiae alcohol dehydrogenase/glyceraldehyde-3-phosphate dehydrogenase (ADH2/GAP).
The control sequence may also be a polyadenylation sequence, a sequence operably linked to the 3′-terminus of the polynucleotide and, when transcribed, is recognized by the host cell as a signal to add polyadenosine residues to transcribed mRNA. Any polyadenylation sequence that is functional in the host cell may be used.
Preferred polyadenylation sequences for filamentous fungal host cells are obtained from the genes for Aspergillus nidulans anthranilate synthase, Aspergillus niger glucoamylase, Aspergillus niger alpha-glucosidase Aspergillus oryzae TAKA amylase, and Fusarium oxysporum trypsin-like protease.
Useful polyadenylation sequences for yeast host cells are described by Guo and Sherman, 1995 , Mol. Cellular Biol. 15: 5983-5990.
The control sequence may also be a signal peptide coding region that encodes a signal peptide linked to the N-terminus of a variant and directs the variant into the cell's secretory pathway. The 5′-end of the coding sequence of the polynucleotide may inherently contain a signal peptide coding sequence naturally linked in translation reading frame with the segment of the coding sequence that encodes the variant. Alternatively, the 5′-end of the coding sequence may contain a signal peptide coding sequence that is foreign to the coding sequence. A foreign signal peptide coding sequence may be required where the coding sequence does not naturally contain a signal peptide coding sequence. Alternatively, a foreign signal peptide coding sequence may simply replace the natural signal peptide coding sequence in order to enhance secretion of the variant. However, any signal peptide coding sequence that directs the expressed variant into the secretory pathway of a host cell may be used.
Effective signal peptide coding sequences for bacterial host cells are the signal peptide coding sequences obtained from the genes for Bacillus NCIB 11837 maltogenic amylase, Bacillus licheniformis subtilisin, Bacillus licheniformis beta-lactamase, Bacillus stearothermophilus alpha-amylase, Bacillus stearothermophilus neutral proteases (nprT, nprS, nprM), and Bacillus subtilis prsA. Further signal peptides are described by Simonen and Palva, 1993 , Microbiological Reviews 57: 109-137.
Effective signal peptide coding sequences for filamentous fungal host cells are the signal peptide coding sequences obtained from the genes for Aspergillus niger neutral amylase, Aspergillus niger glucoamylase, Aspergillus oryzae TAKA amylase, Humicola insolens cellulase, Humicola insolens endoglucanase V, Humicola lanuginosa lipase, and Rhizomucor miehei aspartic proteinase.
Useful signal peptides for yeast host cells are obtained from the genes for Saccharomyces cerevisiae alpha-factor and Saccharomyces cerevisiae invertase. Other useful signal peptide coding sequences are described by Romanos et al., 1992, supra.
The control sequence may also be a propeptide coding sequence that encodes a propeptide positioned at the N-terminus of a variant. The resultant polypeptide is known as a proenzyme or propolypeptide (or a zymogen in some cases). A propolypeptide is generally inactive and can be converted to an active variant by catalytic or autocatalytic cleavage of the propeptide from the propolypeptide. The propeptide coding sequence may be obtained from the genes for Bacillus subtilis alkaline protease (aprE), Bacillus subtilis neutral protease (nprT), Myceliophthora thermophila laccase (WO 95/33836), Rhizomucor miehei aspartic proteinase, and Saccharomyces cerevisiae alpha-factor.
Where both signal peptide and propeptide sequences are present, the propeptide sequence is positioned next to the N-terminus of a variant and the signal peptide sequence is positioned next to the N-terminus of the propeptide sequence.
It may also be desirable to add regulatory sequences that regulate expression of the variant relative to the growth of the host cell. Examples of regulatory sequences are those that cause expression of the gene to be turned on or off in response to a chemical or physical stimulus, including the presence of a regulatory compound. Regulatory sequences in prokaryotic systems include the lac, tac, and trp operator systems. In yeast, the ADH2 system or GAL1 system may be used. In filamentous fungi, the Aspergillus niger glucoamylase promoter, Aspergillus oryzae TAKA alpha-amylase promoter, and Aspergillus oryzae glucoamylase promoter, Trichoderma reesei cellobiohydrolase I promoter, and Trichoderma reesei cellobiohydrolase II promoter may be used. Other examples of regulatory sequences are those that allow for gene amplification. In eukaryotic systems, these regulatory sequences include the dihydrofolate reductase gene that is amplified in the presence of methotrexate, and the metallothionein genes that are amplified with heavy metals. In these cases, the polynucleotide encoding the variant would be operably linked to the regulatory sequence.
Expression Vectors
The present invention also relates to recombinant expression vectors comprising a polynucleotide encoding a variant of the present invention, a promoter, and transcriptional and translational stop signals. The various nucleotide and control sequences may be joined together to produce a recombinant expression vector that may include one or more convenient restriction sites to allow for insertion or substitution of the polynucleotide encoding the variant at such sites. Alternatively, the polynucleotide may be expressed by inserting the polynucleotide or a nucleic acid construct comprising the polynucleotide into an appropriate vector for expression. In creating the expression vector, the coding sequence is located in the vector so that the coding sequence is operably linked with the appropriate control sequences for expression.
The recombinant expression vector may be any vector (e.g., a plasmid or virus) that can be conveniently subjected to recombinant DNA procedures and can bring about expression of the polynucleotide. The choice of the vector will typically depend on the compatibility of the vector with the host cell into which the vector is to be introduced. The vector may be a linear or closed circular plasmid.
The vector may be an autonomously replicating vector, i.e., a vector that exists as an extrachromosomal entity, the replication of which is independent of chromosomal replication, e.g., a plasmid, an extrachromosomal element, a minichromosome, or an artificial chromosome. The vector may contain any means for assuring self-replication. Alternatively, the vector may be one that, when introduced into the host cell, is integrated into the genome and replicated together with the chromosome(s) into which it has been integrated. Furthermore, a single vector or plasmid or two or more vectors or plasmids that together contain the total DNA to be introduced into the genome of the host cell, or a transposon, may be used.
The vector preferably contains one or more selectable markers that permit easy selection of transformed, transfected, transduced, or the like cells. A selectable marker is a gene the product of which provides for biocide or viral resistance, resistance to heavy metals, prototrophy to auxotrophs, and the like.
Examples of bacterial selectable markers are Bacillus licheniformis or Bacillus subtilis dal genes, or markers that confer antibiotic resistance such as ampicillin, chloramphenicol, kanamycin, neomycin, spectinomycin, or tetracycline resistance. Suitable markers for yeast host cells include, but are not limited to, ADE2, HIS3, LEU2, LYS2, MET3, TRP1, and URA3. Selectable markers for use in a filamentous fungal host cell include, but are not limited to, adeA (phosphoribosylaminoimidazole-succinocarboxamide synthase), adeB (phosphoribosyl-aminoimidazole synthase), amdS (acetamidase), argB (ornithine carbamoyltransferase), bar (phosphinothricin acetyltransferase), hph (hygromycin phosphotransferase), niaD (nitrate reductase), pyrG (orotidine-5′-phosphate decarboxylase), sC (sulfate adenyltransferase), and trpC (anthranilate synthase), as well as equivalents thereof. Preferred for use in an Aspergillus cell are Aspergillus nidulans or Aspergillus oryzae amdS and pyrG genes and a Streptomyces hygroscopicus bar gene. Preferred for use in a Trichoderma cell are adeA, adeB, amdS, hph, and pyrG genes.
The selectable marker may be a dual selectable marker system as described in WO 2010/039889. In one aspect, the dual selectable marker is a hph-tk dual selectable marker system.
The vector preferably contains an element(s) that permits integration of the vector into the host cell's genome or autonomous replication of the vector in the cell independent of the genome.
For integration into the host cell genome, the vector may rely on the polynucleotide's sequence encoding the variant or any other element of the vector for integration into the genome by homologous or non-homologous recombination. Alternatively, the vector may contain additional polynucleotides for directing integration by homologous recombination into the genome of the host cell at a precise location(s) in the chromosome(s). To increase the likelihood of integration at a precise location, the integrational elements should contain a sufficient number of nucleic acids, such as 100 to 10,000 base pairs, 400 to 10,000 base pairs, and 800 to 10,000 base pairs, which have a high degree of sequence identity to the corresponding target sequence to enhance the probability of homologous recombination. The integrational elements may be any sequence that is homologous with the target sequence in the genome of the host cell. Furthermore, the integrational elements may be non-encoding or encoding polynucleotides. On the other hand, the vector may be integrated into the genome of the host cell by non-homologous recombination.
For autonomous replication, the vector may further comprise an origin of replication enabling the vector to replicate autonomously in the host cell in question. The origin of replication may be any plasmid replicator mediating autonomous replication that functions in a cell. The term “origin of replication” or “plasmid replicator” means a polynucleotide that enables a plasmid or vector to replicate in vivo.
Examples of bacterial origins of replication are the origins of replication of plasmids pBR322, pUC19, pACYC177, and pACYC184 permitting replication in E. coli , and pUB110, pE194, pTA1060, and pAMR1 permitting replication in Bacillus.
Examples of origins of replication for use in a yeast host cell are the 2 micron origin of replication, ARS1, ARS4, the combination of ARS1 and CEN3, and the combination of ARS4 and CEN6.
Examples of origins of replication useful in a filamentous fungal cell are AMA1 and ANS1 (Gems et al., 1991 , Gene 98: 61-67; Cullen et al., 1987 , Nucleic Acids Res. 15: 9163-9175; WO 00/24883). Isolation of the AMA1 gene and construction of plasmids or vectors comprising the gene can be accomplished according to the methods disclosed in WO 00/24883.
More than one copy of a polynucleotide of the present invention may be inserted into a host cell to increase production of a variant. An increase in the copy number of the polynucleotide can be obtained by integrating at least one additional copy of the sequence into the host cell genome or by including an amplifiable selectable marker gene with the polynucleotide where cells containing amplified copies of the selectable marker gene, and thereby additional copies of the polynucleotide, can be selected for by cultivating the cells in the presence of the appropriate selectable agent.
The procedures used to ligate the elements described above to construct the recombinant expression vectors of the present invention are well known to one skilled in the art (see, e.g., Sambrook et al., 1989, supra).
Host Cells
The present invention also relates to recombinant host cells, comprising a polynucleotide encoding a variant of the present invention operably linked to one or more control sequences that direct the production of a variant of the present invention. A construct or vector comprising a polynucleotide is introduced into a host cell so that the construct or vector is maintained as a chromosomal integrant or as a self-replicating extra-chromosomal vector as described earlier. The term “host cell” encompasses any progeny of a parent cell that is not identical to the parent cell due to mutations that occur during replication. The choice of a host cell will to a large extent depend upon the gene encoding the variant and its source.
The host cell may be any cell useful in the recombinant production of a variant, e.g., a prokaryote or a eukaryote.
The prokaryotic host cell may be any Gram-positive or Gram-negative bacterium. Gram-positive bacteria include, but are not limited to, Bacillus, Clostridium, Enterococcus, Geobacillus, Lactobacillus, Lactococcus, Oceanobacillus, Staphylococcus, Streptococcus , and Streptomyces . Gram-negative bacteria include, but are not limited to, Campylobacter, E. coli, Flavobacterium, Fusobacterium, Helicobacter, Ilyobacter, Neisseria, Pseudomonas, Salmonella , and Ureaplasma.
The bacterial host cell may be any Bacillus cell including, but not limited to, Bacillus alkalophilus, Bacillus amyloliquefaciens, Bacillus brevis, Bacillus circulans, Bacillus clausii, Bacillus coagulans, Bacillus firmus, Bacillus lautus, Bacillus lentus, Bacillus licheniformis, Bacillus megaterium, Bacillus pumilus, Bacillus stearothermophilus, Bacillus subtilis , and Bacillus thuringiensis cells.
The bacterial host cell may also be any Streptococcus cell including, but not limited to, Streptococcus equisimilis, Streptococcus pyogenes, Streptococcus uberis , and Streptococcus equi subsp. Zooepidemicus cells.
The bacterial host cell may also be any Streptomyces cell, including, but not limited to, Streptomyces achromogenes, Streptomyces avermitilis, Streptomyces coelicolor, Streptomyces griseus , and Streptomyces lividans cells.
The introduction of DNA into a Bacillus cell may be effected by protoplast transformation (see, e.g., Chang and Cohen, 1979 , Mol. Gen. Genet. 168: 111-115), competent cell transformation (see, e.g., Young and Spizizen, 1961 , J. Bacteriol. 81: 823-829, or Dubnau and Davidoff-Abelson, 1971 , J. Mol. Biol. 56: 209-221), electroporation (see, e.g., Shigekawa and Dower, 1988 , Biotechniques 6: 742-751), or conjugation (see, e.g., Koehler and Thorne, 1987 , J. Bacteriol. 169: 5271-5278). The introduction of DNA into an E. coli cell may be effected by protoplast transformation (see, e.g., Hanahan, 1983 , J. Mol. Biol. 166: 557-580) or electroporation (see, e.g., Dower et al., 1988 , Nucleic Acids Res. 16: 6127-6145). The introduction of DNA into a Streptomyces cell may be effected by protoplast transformation, electroporation (see, e.g., Gong et al., 2004 , Folia Microbiol . ( Praha ) 49: 399-405), conjugation (see, e.g., Mazodier et al., 1989 , J. Bacteriol. 171: 3583-3585), or transduction (see, e.g., Burke et al., 2001 , Proc. Natl. Acad. Sci. USA 98: 6289-6294). The introduction of DNA into a Pseudomonas cell may be effected by electroporation (see, e.g., Choi et al., 2006 , J. Microbiol. Methods 64: 391-397), or conjugation (see, e.g., Pinedo and Smets, 2005 , Appl. Environ. Microbiol. 71: 51-57). The introduction of DNA into a Streptococcus cell may be effected by natural competence (see, e.g., Perry and Kuramitsu, 1981 , Infect. Immun. 32: 1295-1297), protoplast transformation (see, e.g., Catt and Jollick, 1991 , Microbios 68: 189-207), electroporation (see, e.g., Buckley et al., 1999 , Appl. Environ. Microbiol. 65: 3800-3804), or conjugation (see, e.g., Clewell, 1981 , Microbiol. Rev. 45: 409-436). However, any method known in the art for introducing DNA into a host cell can be used.
The host cell may also be a eukaryote, such as a mammalian, insect, plant, or fungal cell.
The host cell may be a fungal cell. “Fungi” as used herein includes the phyla Ascomycota, Basidiomycota, Chytridiomycota, and Zygomycota as well as the Oomycota and all mitosporic fungi (as defined by Hawksworth et al., In, Ainsworth and Bisby's Dictionary of The Fungi, 8th edition, 1995, CAB International, University Press, Cambridge, UK).
The fungal host cell may be a yeast cell. “Yeast” as used herein includes ascosporogenous yeast (Endomycetales), basidiosporogenous yeast, and yeast belonging to the Fungi Imperfecti (Blastomycetes). Since the classification of yeast may change in the future, for the purposes of this invention, yeast shall be defined as described in Biology and Activities of Yeast (Skinner, Passmore, and Davenport, editors, Soc. App. Bacteriol. Symposium Series No. 9, 1980).
The yeast host cell may be a Candida, Hansenula, Kluyveromyces, Pichia, Saccharomyces, Schizosaccharomyces , or Yarrowia cell such as a Kluyveromyces lactis, Saccharomyces carlsbergensis, Saccharomyces cerevisiae, Saccharomyces diastaticus, Saccharomyces douglasii, Saccharomyces kluyveri, Saccharomyces norbensis, Saccharomyces oviformis , or Yarrowia lipolytica cell.
The fungal host cell may be a filamentous fungal cell. “Filamentous fungi” include all filamentous forms of the subdivision Eumycota and Oomycota (as defined by Hawksworth et al., 1995, supra). The filamentous fungi are generally characterized by a mycelial wall composed of chitin, cellulose, glucan, chitosan, mannan, and other complex polysaccharides. Vegetative growth is by hyphal elongation and carbon catabolism is obligately aerobic. In contrast, vegetative growth by yeasts such as Saccharomyces cerevisiae is by budding of a unicellular thallus and carbon catabolism may be fermentative.
The filamentous fungal host cell may be an Acremonium, Aspergillus, Aureobasidium, Bjerkandera, Ceriporiopsis, Chrysosporium, Coprinus, Coriolus, Cryptococcus, Filibasidium, Fusarium, Humicola, Magnaporthe, Mucor, Myceliophthora, Neocallimastix, Neurospora, Paecilomyces, Penicillium, Phanerochaete, Phlebia, Piromyces, Pleurotus, Schizophyllum, Talaromyces, Thermoascus, Thielavia, Tolypocladium, Trametes , or Trichoderma cell.
For example, the filamentous fungal host cell may be an Aspergillus awamori, Aspergillus foetidus, Aspergillus fumigatus, Aspergillus japonicus, Aspergillus nidulans, Aspergillus niger, Aspergillus oryzae, Bjerkandera adusta, Ceriporiopsis aneirina, Ceriporiopsis caregiea, Ceriporiopsis gilvescens, Ceriporiopsis pannocinta, Ceriporiopsis rivulosa, Ceriporiopsis subrufa, Ceriporiopsis subvermispora, Chrysosporium inops, Chrysosporium keratinophilum, Chrysosporium lucknowense, Chrysosporium merdarium, Chrysosporium pannicola, Chrysosporium queenslandicum, Chrysosporium tropicum, Chrysosporium zonatum, Coprinus cinereus, Coriolus hirsutus, Fusarium bactridioides, Fusarium cerealis, Fusarium crookwellense, Fusarium culmorum, Fusarium graminearum, Fusarium graminum, Fusarium heterosporum, Fusarium negundi, Fusarium oxysporum, Fusarium reticulatum, Fusarium roseum, Fusarium sambucinum, Fusarium sarcochroum, Fusarium sporotrichioides, Fusarium sulphureum, Fusarium torulosum, Fusarium trichothecioides, Fusarium venenatum, Humicola insolens, Humicola lanuginosa, Mucor miehei, Myceliophthora thermophila, Neurospora crassa, Penicillium purpurogenum, Phanerochaete chrysosporium, Phlebia radiata, Pleurotus eryngii, Talaromyces emersonii, Thielavia terrestris, Trametes villosa, Trametes versicolor, Trichoderma harzianum, Trichoderma koningii, Trichoderma longibrachiatum, Trichoderma reesei , or Trichoderma viride cell.
Fungal cells may be transformed by a process involving protoplast formation, transformation of the protoplasts, and regeneration of the cell wall in a manner known per se. Suitable procedures for transformation of Aspergillus and Trichoderma host cells are described in EP 238023, Yelton et al., 1984 , Proc. Natl. Acad. Sci. USA 81: 1470-1474, and Christensen et al., 1988 , Bio/Technology 6: 1419-1422. Suitable methods for transforming Fusarium species are described by Malardier et al., 1989 , Gene 78: 147-156, and WO 96/00787. Yeast may be transformed using the procedures described by Becker and Guarente, In Abelson, J. N. and Simon, M. I., editors, Guide to Yeast Genetics and Molecular Biology, Methods in Enzymology , Volume 194, pp. 182-187, Academic Press, Inc., New York; Ito et al., 1983 , J. Bacteriol. 153: 163; and Hinnen et al., 1978 , Proc. Natl. Acad. Sci. USA 75: 1920.
Methods of Production
The present invention also relates to methods of producing a variant, comprising (a) cultivating a recombinant host cell of the present invention under conditions conducive for production of the variant; and optionally (b) recovering the variant.
The host cells are cultivated in a nutrient medium suitable for production of the variant using methods known in the art. For example, the cells may be cultivated by shake flask cultivation, or small-scale or large-scale fermentation (including continuous, batch, fed-batch, or solid state fermentations) in laboratory or industrial fermentors in a suitable medium and under conditions allowing the variant to be expressed and/or isolated. The cultivation takes place in a suitable nutrient medium comprising carbon and nitrogen sources and inorganic salts, using procedures known in the art. Suitable media are available from commercial suppliers or may be prepared according to published compositions (e.g., in catalogues of the American Type Culture Collection). If the variant is secreted into the nutrient medium, the variant can be recovered directly from the medium. If the variant is not secreted, it can be recovered from cell lysates.
The variants may be detected using methods known in the art that are specific for the variants. These detection methods include, but are not limited to, use of specific antibodies, formation of an enzyme product, or disappearance of an enzyme substrate. For example, an enzyme assay may be used to determine the activity of the variant.
The variant may be recovered using methods known in the art. For example, the variant may be recovered from the nutrient medium by conventional procedures including, but not limited to, collection, centrifugation, filtration, extraction, spray-drying, evaporation, or precipitation. In one aspect, a whole fermentation broth comprising a variant of the present invention is recovered.
The variant may be purified by a variety of procedures known in the art including, but not limited to, chromatography (e.g., ion exchange, affinity, hydrophobic, chromatofocusing, and size exclusion), electrophoretic procedures (e.g., preparative isoelectric focusing), differential solubility (e.g., ammonium sulfate precipitation), SDS-PAGE, or extraction (see, e.g., Protein Purification , Janson and Ryden, editors, VCH Publishers, New York, 1989) to obtain substantially pure variants.
Fermentation Broth Formulations or Cell Compositions
The present invention also relates to a fermentation broth formulation or a cell composition comprising a variant of the present invention. The fermentation broth product further comprises additional ingredients used in the fermentation process, such as, for example, cells (including, the host cells containing the gene encoding the variant of the present invention which are used to produce the variant), cell debris, biomass, fermentation media and/or fermentation products. In some embodiments, the composition is a cell-killed whole broth containing organic acid(s), killed cells and/or cell debris, and culture medium.
The term “fermentation broth” as used herein refers to a preparation produced by cellular fermentation that undergoes no or minimal recovery and/or purification. For example, fermentation broths are produced when microbial cultures are grown to saturation, incubated under carbon-limiting conditions to allow protein synthesis (e.g., expression of enzymes by host cells) and secretion into cell culture medium. The fermentation broth can contain unfractionated or fractionated contents of the fermentation materials derived at the end of the fermentation. Typically, the fermentation broth is unfractionated and comprises the spent culture medium and cell debris present after the microbial cells (e.g., filamentous fungal cells) are removed, e.g., by centrifugation. In some embodiments, the fermentation broth contains spent cell culture medium, extracellular enzymes, and viable and/or nonviable microbial cells.
In an embodiment, the fermentation broth formulation and cell compositions comprise a first organic acid component comprising at least one 1-5 carbon organic acid and/or a salt thereof and a second organic acid component comprising at least one 6 or more carbon organic acid and/or a salt thereof. In a specific embodiment, the first organic acid component is acetic acid, formic acid, propionic acid, a salt thereof, or a mixture of two or more of the foregoing and the second organic acid component is benzoic acid, cyclohexanecarboxylic acid, 4-methylvaleric acid, phenylacetic acid, a salt thereof, or a mixture of two or more of the foregoing.
In one aspect, the composition contains an organic acid(s), and optionally further contains killed cells and/or cell debris. In one embodiment, the killed cells and/or cell debris are removed from a cell-killed whole broth to provide a composition that is free of these components.
The fermentation broth formulations or cell compositions may further comprise a preservative and/or anti-microbial (e.g., bacteriostatic) agent, including, but not limited to, sorbitol, sodium chloride, potassium sorbate, and others known in the art.
The fermentation broth formulations or cell compositions may further comprise multiple enzymatic activities, such as one or more (e.g., several) enzymes selected from the group consisting of a cellulase, a hemicellulase, a catalase, an esterase, an expansin, a laccase, a ligninolytic enzyme, a pectinase, a peroxidase, a protease, and a swollenin. The fermentation broth formulations or cell compositions may also comprise one or more (e.g., several) enzymes selected from the group consisting of a hydrolase, an isomerase, a ligase, a lyase, an oxidoreductase, or a transferase, e.g., an alpha-galactosidase, alpha-glucosidase, aminopeptidase, amylase, beta-galactosidase, beta-glucosidase, beta-xylosidase, carbohydrase, carboxypeptidase, catalase, cellobiohydrolase, cellulase, chitinase, cutinase, cyclodextrin glycosyltransferase, deoxyribonuclease, endoglucanase, esterase, glucoamylase, invertase, laccase, lipase, mannosidase, mutanase, oxidase, pectinolytic enzyme, peroxidase, phytase, polyphenoloxidase, proteolytic enzyme, ribonuclease, transglutaminase, or xylanase.
The cell-killed whole broth or composition may contain the unfractionated contents of the fermentation materials derived at the end of the fermentation. Typically, the cell-killed whole broth or composition contains the spent culture medium and cell debris present after the microbial cells (e.g., filamentous fungal cells) are grown to saturation, incubated under carbon-limiting conditions to allow protein synthesis (e.g., expression of cellulase and/or glucosidase enzyme(s)). In some embodiments, the cell-killed whole broth or composition contains the spent cell culture medium, extracellular enzymes, and killed filamentous fungal cells. In some embodiments, the microbial cells present in the cell-killed whole broth or composition can be permeabilized and/or lysed using methods known in the art.
A whole broth or cell composition as described herein is typically a liquid, but may contain insoluble components, such as killed cells, cell debris, culture media components, and/or insoluble enzyme(s). In some embodiments, insoluble components may be removed to provide a clarified liquid composition.
The whole broth formulations and cell compositions of the present invention may be produced by a method described in WO 90/15861 or WO 2010/096673.
Examples are given below of preferred uses of the compositions of the present invention. The dosage of the composition and other conditions under which the composition is used may be determined on the basis of methods known in the art.
Enzyme Compositions
The present invention also relates to compositions comprising a variant of the present invention. Preferably, the compositions are enriched in such a variant. The term “enriched” indicates that the cellobiohydrolase activity of the composition has been increased, e.g., with an enrichment factor of at least 1.1.
The compositions may comprise a variant of the present invention as the major enzymatic component, e.g., a mono-component composition. Alternatively, the compositions may comprise multiple enzymatic activities, such as one or more (e.g., several) enzymes selected from the group consisting of a cellulase, a hemicellulase, a GH61 polypeptide having cellulolytic enhancing activity, a catalase, an esterase, an expansin, a laccase, a ligninolytic enzyme, a pectinase, a peroxidase, a protease, and a swollenin. The compositions may also comprise one or more (e.g., several) enzymes selected from the group consisting of a hydrolase, an isomerase, a ligase, a lyase, an oxidoreductase, or a transferase, e.g., an alpha-galactosidase, alpha-glucosidase, aminopeptidase, amylase, beta-galactosidase, beta-glucosidase, beta-xylosidase, carbohydrase, carboxypeptidase, catalase, cellobiohydrolase, cellulase, chitinase, cutinase, cyclodextrin glycosyltransferase, deoxyribonuclease, endoglucanase, esterase, glucoamylase, invertase, laccase, lipase, mannosidase, mutanase, oxidase, pectinolytic enzyme, peroxidase, phytase, polyphenoloxidase, proteolytic enzyme, ribonuclease, transglutaminase, or xylanase. The compositions may be prepared in accordance with methods known in the art and may be in the form of a liquid or a dry composition. The compositions may be stabilized in accordance with methods known in the art.
Examples are given below of preferred uses of the compositions of the present invention. The dosage of the composition and other conditions under which the composition is used may be determined on the basis of methods known in the art.
Uses
The present invention is also directed to the following processes for using the variants having cellobiohydrolase I activity of the present invention, or compositions thereof.
The present invention also relates to processes for degrading a cellulosic material, comprising: treating the cellulosic material with an enzyme composition in the presence of a cellobiohydrolase variant of the present invention. In one aspect, the processes further comprise recovering the degraded cellulosic material. Soluble products of degradation of the cellulosic material can be separated from insoluble cellulosic material using a method known in the art such as, for example, centrifugation, filtration, or gravity settling.
The present invention also relates to processes of producing a fermentation product, comprising: (a) saccharifying a cellulosic material with an enzyme composition in the presence of a cellobiohydrolase variant of the present invention; (b) fermenting the saccharified cellulosic material with one or more (e.g., several) fermenting microorganisms to produce the fermentation product; and (c) recovering the fermentation product from the fermentation.
The present invention also relates to processes of fermenting a cellulosic material, comprising: fermenting the cellulosic material with one or more (e.g., several) fermenting microorganisms, wherein the cellulosic material is saccharified with an enzyme composition in the presence of a cellobiohydrolase variant of the present invention. In one aspect, the fermenting of the cellulosic material produces a fermentation product. In another aspect, the processes further comprise recovering the fermentation product from the fermentation.
The processes of the present invention can be used to saccharify the cellulosic material to fermentable sugars and to convert the fermentable sugars to many useful fermentation products, e.g., fuel (ethanol, n-butanol, isobutanol, biodiesel, jet fuel) and/or platform chemicals (e.g., acids, alcohols, ketones, gases, oils, and the like). The production of a desired fermentation product from the cellulosic material typically involves pretreatment, enzymatic hydrolysis (saccharification), and fermentation.
The processing of the cellulosic material according to the present invention can be accomplished using methods conventional in the art. Moreover, the processes of the present invention can be implemented using any conventional biomass processing apparatus configured to operate in accordance with the invention.
Hydrolysis (saccharification) and fermentation, separate or simultaneous, include, but are not limited to, separate hydrolysis and fermentation (SHF); simultaneous saccharification and fermentation (SSF); simultaneous saccharification and co-fermentation (SSCF); hybrid hydrolysis and fermentation (HHF); separate hydrolysis and co-fermentation (SHCF); hybrid hydrolysis and co-fermentation (HHCF); and direct microbial conversion (DMC), also sometimes called consolidated bioprocessing (CBP). SHF uses separate process steps to first enzymatically hydrolyze the cellulosic material to fermentable sugars, e.g., glucose, cellobiose, and pentose monomers, and then ferment the fermentable sugars to ethanol. In SSF, the enzymatic hydrolysis of the cellulosic material and the fermentation of sugars to ethanol are combined in one step (Philippidis, G. P., 1996, Cellulose bioconversion technology, in Handbook on Bioethanol: Production and Utilization , Wyman, C. E., ed., Taylor & Francis, Washington, D.C., 179-212). SSCF involves the co-fermentation of multiple sugars (Sheehan and Himmel, 1999 , Biotechnol. Prog. 15: 817-827). HHF involves a separate hydrolysis step, and in addition a simultaneous saccharification and hydrolysis step, which can be carried out in the same reactor. The steps in an HHF process can be carried out at different temperatures, i.e., high temperature enzymatic saccharification followed by SSF at a lower temperature that the fermentation strain can tolerate. DMC combines all three processes (enzyme production, hydrolysis, and fermentation) in one or more (e.g., several) steps where the same organism is used to produce the enzymes for conversion of the cellulosic material to fermentable sugars and to convert the fermentable sugars into a final product (Lynd et al., 2002 , Microbiol. Mol. Biol. Reviews 66: 506-577). It is understood herein that any method known in the art comprising pretreatment, enzymatic hydrolysis (saccharification), fermentation, or a combination thereof, can be used in the practicing the processes of the present invention.
A conventional apparatus can include a fed-batch stirred reactor, a batch stirred reactor, a continuous flow stirred reactor with ultrafiltration, and/or a continuous plug-flow column reactor (de Castilhos Corazza et al., 2003 , Acta Scientiarum. Technology 25: 33-38; Gusakov and Sinitsyn, 1985 , Enz. Microb. Technol. 7: 346-352), an attrition reactor (Ryu and Lee, 1983 , Biotechnol. Bioeng. 25: 53-65). Additional reactor types include fluidized bed, upflow blanket, immobilized, and extruder type reactors for hydrolysis and/or fermentation.
Pretreatment.
In practicing the processes of the present invention, any pretreatment process known in the art can be used to disrupt plant cell wall components of the cellulosic material (Chandra et al., 2007 , Adv. Biochem. Engin./Biotechnol. 108: 67-93; Galbe and Zacchi, 2007 , Adv. Biochem. Engin./Biotechnol. 108: 41-65; Hendriks and Zeeman, 2009 , Bioresource Technol. 100: 10-18; Mosier et al., 2005 , Bioresource Technol. 96: 673-686; Taherzadeh and Karimi, 2008 , Int. J. Mol. Sci. 9: 1621-1651; Yang and Wyman, 2008 , Biofuels Bioproducts and Biorefining - Biofpr. 2: 26-40).
The cellulosic material can also be subjected to particle size reduction, sieving, pre-soaking, wetting, washing, and/or conditioning prior to pretreatment using methods known in the art.
Conventional pretreatments include, but are not limited to, steam pretreatment (with or without explosion), dilute acid pretreatment, hot water pretreatment, alkaline pretreatment, lime pretreatment, wet oxidation, wet explosion, ammonia fiber explosion, organosolv pretreatment, and biological pretreatment. Additional pretreatments include ammonia percolation, ultrasound, electroporation, microwave, supercritical CO 2 , supercritical H 2 O, ozone, ionic liquid, and gamma irradiation pretreatments.
The cellulosic material can be pretreated before hydrolysis and/or fermentation. Pretreatment is preferably performed prior to the hydrolysis. Alternatively, the pretreatment can be carried out simultaneously with enzyme hydrolysis to release fermentable sugars, such as glucose, xylose, and/or cellobiose. In most cases the pretreatment step itself results in some conversion of biomass to fermentable sugars (even in absence of enzymes).
Steam Pretreatment. In steam pretreatment, the cellulosic material is heated to disrupt the plant cell wall components, including lignin, hemicellulose, and cellulose to make the cellulose and other fractions, e.g., hemicellulose, accessible to enzymes. The cellulosic material is passed to or through a reaction vessel where steam is injected to increase the temperature to the required temperature and pressure and is retained therein for the desired reaction time. Steam pretreatment is preferably performed at 140-250° C., e.g., 160-200° C. or 170-190° C., where the optimal temperature range depends on optional addition of a chemical catalyst. Residence time for the steam pretreatment is preferably 1-60 minutes, e.g., 1-30 minutes, 1-20 minutes, 3-12 minutes, or 4-10 minutes, where the optimal residence time depends on the temperature and optional addition of a chemical catalyst. Steam pretreatment allows for relatively high solids loadings, so that the cellulosic material is generally only moist during the pretreatment. The steam pretreatment is often combined with an explosive discharge of the material after the pretreatment, which is known as steam explosion, that is, rapid flashing to atmospheric pressure and turbulent flow of the material to increase the accessible surface area by fragmentation (Duff and Murray, 1996 , Bioresource Technology 855: 1-33; Galbe and Zacchi, 2002 , Appl. Microbiol. Biotechnol. 59: 618-628; U.S. Patent Application No. 2002/0164730). During steam pretreatment, hemicellulose acetyl groups are cleaved and the resulting acid autocatalyzes partial hydrolysis of the hemicellulose to monosaccharides and oligosaccharides. Lignin is removed to only a limited extent.
Chemical Pretreatment: The term “chemical treatment” refers to any chemical pretreatment that promotes the separation and/or release of cellulose, hemicellulose, and/or lignin. Such a pretreatment can convert crystalline cellulose to amorphous cellulose. Examples of suitable chemical pretreatment processes include, for example, dilute acid pretreatment, lime pretreatment, wet oxidation, ammonia fiber/freeze expansion (AFEX), ammonia percolation (APR), ionic liquid, and organosolv pretreatments.
A chemical catalyst such as H 2 SO 4 or SO 2 (typically 0.3 to 5% w/w) is sometimes added prior to steam pretreatment, which decreases the time and temperature, increases the recovery, and improves enzymatic hydrolysis (Ballesteros et al., 2006 , Appl. Biochem. Biotechnol. 129-132: 496-508; Varga et al., 2004 , Appl. Biochem. Biotechnol. 113-116: 509-523; Sassner et al., 2006 , Enzyme Microb. Technol. 39: 756-762). In dilute acid pretreatment, the cellulosic material is mixed with dilute acid, typically H 2 SO 4 , and water to form a slurry, heated by steam to the desired temperature, and after a residence time flashed to atmospheric pressure. The dilute acid pretreatment can be performed with a number of reactor designs, e.g., plug-flow reactors, counter-current reactors, or continuous counter-current shrinking bed reactors (Duff and Murray, 1996, supra; Schell et al., 2004 , Bioresource Technology 91: 179-188; Lee et al., 1999 , Adv. Biochem. Eng. Biotechnol. 65: 93-115).
Several methods of pretreatment under alkaline conditions can also be used. These alkaline pretreatments include, but are not limited to, sodium hydroxide, lime, wet oxidation, ammonia percolation (APR), and ammonia fiber/freeze expansion (AFEX) pretreatment.
Lime pretreatment is performed with calcium oxide or calcium hydroxide at temperatures of 85-150° C. and residence times from 1 hour to several days (Wyman et al., 2005 , Bioresource Technol. 96: 1959-1966; Mosier et al., 2005 , Bioresource Technol. 96: 673-686). WO 2006/110891, WO 2006/110899, WO 2006/110900, and WO 2006/110901 disclose pretreatment methods using ammonia.
Wet oxidation is a thermal pretreatment performed typically at 180-200° C. for 5-15 minutes with addition of an oxidative agent such as hydrogen peroxide or over-pressure of oxygen (Schmidt and Thomsen, 1998 , Bioresource Technol. 64: 139-151; Palonen et al., 2004 , Appl. Biochem. Biotechnol. 117: 1-17; Varga et al., 2004 , Biotechnol. Bioeng. 88: 567-574; Martin et al., 2006 , J. Chem. Technol. Biotechnol. 81: 1669-1677). The pretreatment is performed preferably at 1-40% dry matter, e.g., 2-30% dry matter or 5-20% dry matter, and often the initial pH is increased by the addition of alkali such as sodium carbonate.
A modification of the wet oxidation pretreatment method, known as wet explosion (combination of wet oxidation and steam explosion) can handle dry matter up to 30%. In wet explosion, the oxidizing agent is introduced during pretreatment after a certain residence time. The pretreatment is then ended by flashing to atmospheric pressure (WO 2006/032282).
Ammonia fiber expansion (AFEX) involves treating the cellulosic material with liquid or gaseous ammonia at moderate temperatures such as 90-150° C. and high pressure such as 17-20 bar for 5-10 minutes, where the dry matter content can be as high as 60% (Gollapalli et al., 2002 , Appl. Biochem. Biotechnol. 98: 23-35; Chundawat et al., 2007 , Biotechnol. Bioeng. 96: 219-231; Alizadeh et al., 2005 , Appl. Biochem. Biotechnol. 121: 1133-1141; Teymouri et al., 2005 , Bioresource Technology 96: 2014-2018). During AFEX pretreatment cellulose and hemicelluloses remain relatively intact. Lignin-carbohydrate complexes are cleaved.
Organosolv pretreatment delignifies the cellulosic material by extraction using aqueous ethanol (40-60% ethanol) at 160-200° C. for 30-60 minutes (Pan et al., 2005 , Biotechnol. Bioeng. 90: 473-481; Pan et al., 2006 , Biotechnol. Bioeng. 94: 851-861; Kurabi et al., 2005 , Appl. Biochem. Biotechnol. 121: 219-230). Sulphuric acid is usually added as a catalyst. In organosolv pretreatment, the majority of hemicellulose and lignin is removed.
Other examples of suitable pretreatment methods are described by Schell et al., 2003 , Appl. Biochem. Biotechnol. 105-108: 69-85, and Mosier et al., 2005 , Bioresource Technology 96: 673-686, and U.S. Published Application 2002/0164730.
In one aspect, the chemical pretreatment is preferably carried out as a dilute acid treatment, and more preferably as a continuous dilute acid treatment. The acid is typically sulfuric acid, but other acids can also be used, such as acetic acid, citric acid, nitric acid, phosphoric acid, tartaric acid, succinic acid, hydrogen chloride, or mixtures thereof. Mild acid treatment is conducted in the pH range of preferably 1-5, e.g., 1-4 or 1-2.5. In one aspect, the acid concentration is in the range from preferably 0.01 to 10 wt. % acid, e.g., 0.05 to 5 wt. % acid or 0.1 to 2 wt. % acid. The acid is contacted with the cellulosic material and held at a temperature in the range of preferably 140-200° C., e.g., 165-190° C., for periods ranging from 1 to 60 minutes.
In another aspect, pretreatment takes place in an aqueous slurry. In preferred aspects, the cellulosic material is present during pretreatment in amounts preferably between 10-80 wt %, e.g., 20-70 wt % or 30-60 wt %, such as around 40 wt %. The pretreated cellulosic material can be unwashed or washed using any method known in the art, e.g., washed with water.
Mechanical Pretreatment or Physical Pretreatment: The term “mechanical pretreatment” or “physical pretreatment” refers to any pretreatment that promotes size reduction of particles. For example, such pretreatment can involve various types of grinding or milling (e.g., dry milling, wet milling, or vibratory ball milling).
The cellulosic material can be pretreated both physically (mechanically) and chemically. Mechanical or physical pretreatment can be coupled with steaming/steam explosion, hydrothermolysis, dilute or mild acid treatment, high temperature, high pressure treatment, irradiation (e.g., microwave irradiation), or combinations thereof. In one aspect, high pressure means pressure in the range of preferably about 100 to about 400 psi, e.g., about 150 to about 250 psi. In another aspect, high temperature means temperature in the range of about 100 to about 300° C., e.g., about 140 to about 200° C. In a preferred aspect, mechanical or physical pretreatment is performed in a batch-process using a steam gun hydrolyzer system that uses high pressure and high temperature as defined above, e.g., a Sunds Hydrolyzer available from Sunds Defibrator AB, Sweden. The physical and chemical pretreatments can be carried out sequentially or simultaneously, as desired.
Accordingly, in a preferred aspect, the cellulosic material is subjected to physical (mechanical) or chemical pretreatment, or any combination thereof, to promote the separation and/or release of cellulose, hemicellulose, and/or lignin.
Biological Pretreatment: The term “biological pretreatment” refers to any biological pretreatment that promotes the separation and/or release of cellulose, hemicellulose, and/or lignin from the cellulosic material. Biological pretreatment techniques can involve applying lignin-solubilizing microorganisms and/or enzymes (see, for example, Hsu, T.-A., 1996, Pretreatment of biomass, in Handbook on Bioethanol: Production and Utilization , Wyman, C. E., ed., Taylor & Francis, Washington, D.C., 179-212; Ghosh and Singh, 1993 , Adv. Appl. Microbiol. 39: 295-333; McMillan, J. D., 1994, Pretreating lignocellulosic biomass: a review, in Enzymatic Conversion of Biomass for Fuels Production , Himmel, M. E., Baker, J. O., and Overend, R. P., eds., ACS Symposium Series 566, American Chemical Society, Washington, D.C., chapter 15; Gong, C. S., Cao, N. J., Du, J., and Tsao, G. T., 1999, Ethanol production from renewable resources, in Advances in Biochemical Engineering/Biotechnology , Scheper, T., ed., Springer-Verlag Berlin Heidelberg, Germany, 65: 207-241; Olsson and Hahn-Hagerdal, 1996 , Enz. Microb. Tech. 18: 312-331; and Vallander and Eriksson, 1990 , Adv. Biochem. Eng./Biotechnol. 42: 63-95).
Saccharification.
In the hydrolysis step, also known as saccharification, the cellulosic material, e.g., pretreated, is hydrolyzed to break down cellulose and/or hemicellulose to fermentable sugars, such as glucose, cellobiose, xylose, xylulose, arabinose, mannose, galactose, and/or soluble oligosaccharides. The hydrolysis is performed enzymatically by an enzyme composition in the presence of a cellobiohydrolase variant of the present invention. The enzymes of the compositions can be added simultaneously or sequentially.
Enzymatic hydrolysis is preferably carried out in a suitable aqueous environment under conditions that can be readily determined by one skilled in the art. In one aspect, hydrolysis is performed under conditions suitable for the activity of the enzymes(s), i.e., optimal for the enzyme(s). The hydrolysis can be carried out as a fed batch or continuous process where the cellulosic material is fed gradually to, for example, an enzyme containing hydrolysis solution.
The saccharification is generally performed in stirred-tank reactors or fermentors under controlled pH, temperature, and mixing conditions. Suitable process time, temperature and pH conditions can readily be determined by one skilled in the art. For example, the saccharification can last up to 200 hours, but is typically performed for preferably about 12 to about 120 hours, e.g., about 16 to about 72 hours or about 24 to about 48 hours. The temperature is in the range of preferably about 25° C. to about 70° C., e.g., about 30° C. to about 65° C., about 40° C. to about 60° C., or about 50° C. to about 55° C. The pH is in the range of preferably about 3 to about 8, e.g., about 3.5 to about 7, about 4 to about 6, or about 4.5 to about 5.5. The dry solids content is in the range of preferably about 5 to about 50 wt %, e.g., about 10 to about 40 wt % or about 20 to about 30 wt %.
The enzyme compositions can comprise any protein useful in degrading the cellulosic material.
In one aspect, the enzyme composition comprises or further comprises one or more (e.g., several) proteins selected from the group consisting of a cellulase, a GH61 polypeptide having cellulolytic enhancing activity, a hemicellulase, an esterase, an expansin, a ligninolytic enzyme, an oxidoreductase, a pectinase, a protease, and a swollenin. In another aspect, the cellulase is preferably one or more (e.g., several) enzymes selected from the group consisting of an endoglucanase, a cellobiohydrolase, and a beta-glucosidase. In another aspect, the hemicellulase is preferably one or more (e.g., several) enzymes selected from the group consisting of an acetylmannan esterase, an acetylxylan esterase, an arabinanase, an arabinofuranosidase, a coumaric acid esterase, a feruloyl esterase, a galactosidase, a glucuronidase, a glucuronoyl esterase, a mannanase, a mannosidase, a xylanase, and a xylosidase. In another aspect, the oxidoreductase is preferably one or more (e.g., several) enzymes selected from the group consisting of a catalase, a laccase, and a peroxidase.
In another aspect, the enzyme composition comprises one or more (e.g., several) cellulolytic enzymes. In another aspect, the enzyme composition comprises or further comprises one or more (e.g., several) hemicellulolytic enzymes. In another aspect, the enzyme composition comprises one or more (e.g., several) cellulolytic enzymes and one or more (e.g., several) hemicellulolytic enzymes. In another aspect, the enzyme composition comprises one or more (e.g., several) enzymes selected from the group of cellulolytic enzymes and hemicellulolytic enzymes. In another aspect, the enzyme composition comprises an endoglucanase. In another aspect, the enzyme composition comprises a cellobiohydrolase. In another aspect, the enzyme composition comprises a beta-glucosidase. In another aspect, the enzyme composition comprises a GH61 polypeptide having cellulolytic enhancing activity. In another aspect, the enzyme composition comprises an endoglucanase and a GH61 polypeptide having cellulolytic enhancing activity. In another aspect, the enzyme composition comprises a cellobiohydrolase and a GH61 polypeptide having cellulolytic enhancing activity. In another aspect, the enzyme composition comprises a beta-glucosidase and a GH61 polypeptide having cellulolytic enhancing activity. In another aspect, the enzyme composition comprises an endoglucanase and a cellobiohydrolase. In another aspect, the enzyme composition comprises an endoglucanase and a cellobiohydrolase I, a cellobiohydrolase II, or a combination of a cellobiohydrolase I and a cellobiohydrolase II. In another aspect, the enzyme composition comprises an endoglucanase and a beta-glucosidase. In another aspect, the enzyme composition comprises a beta-glucosidase and a cellobiohydrolase. In another aspect, the enzyme composition comprises a beta-glucosidase and a cellobiohydrolase I, a cellobiohydrolase II, or a combination of a cellobiohydrolase I and a cellobiohydrolase II In another aspect, the enzyme composition comprises an endoglucanase, a GH61 polypeptide having cellulolytic enhancing activity, and a cellobiohydrolase. In another aspect, the enzyme composition comprises an endoglucanase, a GH61 polypeptide having cellulolytic enhancing activity, and a cellobiohydrolase I, a cellobiohydrolase II, or a combination of a cellobiohydrolase I and a cellobiohydrolase II. In another aspect, the enzyme composition comprises an endoglucanase, a beta-glucosidase, and a GH61 polypeptide having cellulolytic enhancing activity. In another aspect, the enzyme composition comprises a beta-glucosidase, a GH61 polypeptide having cellulolytic enhancing activity, and a cellobiohydrolase. In another aspect, the enzyme composition comprises a beta-glucosidase, a GH61 polypeptide having cellulolytic enhancing activity, and a cellobiohydrolase I, a cellobiohydrolase II, or a combination of a cellobiohydrolase I and a cellobiohydrolase II. In another aspect, the enzyme composition comprises an endoglucanase, a beta-glucosidase, and a cellobiohydrolase. In another aspect, the enzyme composition comprises an endoglucanase, a beta-glucosidase, and a cellobiohydrolase I, a cellobiohydrolase II, or a combination of a cellobiohydrolase I and a cellobiohydrolase II. In another aspect, the enzyme composition comprises an endoglucanase, a cellobiohydrolase, a beta-glucosidase, and a GH61 polypeptide having cellulolytic enhancing activity. In another aspect, the enzyme composition comprises an endoglucanase, a beta-glucosidase, a GH61 polypeptide having cellulolytic enhancing activity, and a cellobiohydrolase I, a cellobiohydrolase II, or a combination of a cellobiohydrolase I and a cellobiohydrolase II.
In another aspect, the enzyme composition comprises an acetylmannan esterase. In another aspect, the enzyme composition comprises an acetylxylan esterase. In another aspect, the enzyme composition comprises an arabinanase (e.g., alpha-L-arabinanase). In another aspect, the enzyme composition comprises an arabinofuranosidase (e.g., alpha-L-arabinofuranosidase). In another aspect, the enzyme composition comprises a coumaric acid esterase. In another aspect, the enzyme composition comprises a feruloyl esterase. In another aspect, the enzyme composition comprises a galactosidase (e.g., alpha-galactosidase and/or beta-galactosidase). In another aspect, the enzyme composition comprises a glucuronidase (e.g., alpha-D-glucuronidase). In another aspect, the enzyme composition comprises a glucuronoyl esterase. In another aspect, the enzyme composition comprises a mannanase. In another aspect, the enzyme composition comprises a mannosidase (e.g., beta-mannosidase). In another aspect, the enzyme composition comprises a xylanase. In a preferred aspect, the xylanase is a Family 10 xylanase. In another preferred aspect, the xylanase is a Family 11 xylanase. In another aspect, the enzyme composition comprises a xylosidase (e.g., beta-xylosidase).
In another aspect, the enzyme composition comprises an esterase. In another aspect, the enzyme composition comprises an expansin. In another aspect, the enzyme composition comprises a ligninolytic enzyme. In a preferred aspect, the ligninolytic enzyme is a manganese peroxidase. In another preferred aspect, the ligninolytic enzyme is a lignin peroxidase. In another preferred aspect, the ligninolytic enzyme is a H 2 O 2 -producing enzyme. In another aspect, the enzyme composition comprises a pectinase. In another aspect, the enzyme composition comprises an oxidoreductase. In another preferred aspect, the oxidoreductase is a catalase. In another preferred aspect, the oxidoreductase is a laccase. In another preferred aspect, the oxidoreductase is a peroxidase. In another aspect, the enzyme composition comprises a protease. In another aspect, the enzyme composition comprises a swollenin.
In the processes of the present invention, the enzyme(s) can be added prior to or during saccharification, saccharification and fermentation, or fermentation.
One or more (e.g., several) components of the enzyme composition may be native proteins, recombinant proteins, or a combination of native proteins and recombinant proteins. For example, one or more (e.g., several) components may be native proteins of a cell, which is used as a host cell to express recombinantly one or more (e.g., several) other components of the enzyme composition. It is understood herein that the recombinant proteins may be heterologous (e.g., foreign) and native to the host cell. One or more (e.g., several) components of the enzyme composition may be produced as monocomponents, which are then combined to form the enzyme composition. The enzyme composition may be a combination of multicomponent and monocomponent protein preparations.
The enzymes used in the processes of the present invention may be in any form suitable for use, such as, for example, a fermentation broth formulation or a cell composition, a cell lysate with or without cellular debris, a semi-purified or purified enzyme preparation, or a host cell as a source of the enzymes. The enzyme composition may be a dry powder or granulate, a non-dusting granulate, a liquid, a stabilized liquid, or a stabilized protected enzyme. Liquid enzyme preparations may, for instance, be stabilized by adding stabilizers such as a sugar, a sugar alcohol or another polyol, and/or lactic acid or another organic acid according to established processes.
The optimum amounts of the enzymes and the cellobiohydrolase variant depend on several factors including, but not limited to, the mixture of component cellulolytic enzymes and/or hemicellulolytic enzymes, the cellulosic material, the concentration of cellulosic material, the pretreatment(s) of the cellulosic material, temperature, time, pH, and inclusion of fermenting organism (e.g., for Simultaneous Saccharification and Fermentation).
In one aspect, an effective amount of cellulolytic or hemicellulolytic enzyme to the cellulosic material is about 0.5 to about 50 mg, e.g., about 0.5 to about 40 mg, about 0.5 to about 25 mg, about 0.75 to about 20 mg, about 0.75 to about 15 mg, about 0.5 to about 10 mg, or about 2.5 to about 10 mg per g of the cellulosic material.
In another aspect, an effective amount of a cellobiohydrolase variant to the cellulosic material is about 0.01 to about 50.0 mg, e.g., about 0.01 to about 40 mg, about 0.01 to about 30 mg, about 0.01 to about 20 mg, about 0.01 to about 10 mg, about 0.01 to about 5 mg, about 0.025 to about 1.5 mg, about 0.05 to about 1.25 mg, about 0.075 to about 1.25 mg, about 0.1 to about 1.25 mg, about 0.15 to about 1.25 mg, or about 0.25 to about 1.0 mg per g of the cellulosic material.
In another aspect, an effective amount of a cellobiohydrolase variant to cellulolytic or hemicellulolytic enzyme is about 0.005 to about 1.0 g, e.g., about 0.01 to about 1.0 g, about 0.15 to about 0.75 g, about 0.15 to about 0.5 g, about 0.1 to about 0.5 g, about 0.1 to about 0.25 g, or about 0.05 to about 0.2 g per g of cellulolytic or hemicellulolytic enzyme.
The polypeptides having cellulolytic enzyme activity or hemicellulolytic enzyme activity as well as other proteins/polypeptides useful in the degradation of the cellulosic material, e.g., GH61 polypeptides having cellulolytic enhancing activity, (collectively hereinafter “polypeptides having enzyme activity”) can be derived or obtained from any suitable origin, including, archaeal, bacterial, fungal, yeast, plant, or animal origin. The term “obtained” also means herein that the enzyme may have been produced recombinantly in a host organism employing methods described herein, wherein the recombinantly produced enzyme is either native or foreign to the host organism or has a modified amino acid sequence, e.g., having one or more (e.g., several) amino acids that are deleted, inserted and/or substituted, i.e., a recombinantly produced enzyme that is a mutant and/or a fragment of a native amino acid sequence or an enzyme produced by nucleic acid shuffling processes known in the art. Encompassed within the meaning of a native enzyme are natural variants and within the meaning of a foreign enzyme are variants obtained by, for example, site-directed mutagenesis or shuffling.
A polypeptide having enzyme activity may be a bacterial polypeptide. For example, the polypeptide may be a Gram positive bacterial polypeptide such as a Bacillus, Streptococcus, Streptomyces, Staphylococcus, Enterococcus, Lactobacillus, Lactococcus, Clostridium, Geobacillus, Caldicellulosiruptor, Acidothermus, Thermobifidia , or Oceanobacillus polypeptide having enzyme activity, or a Gram negative bacterial polypeptide such as an E. coli, Pseudomonas, Salmonella, Campylobacter, Helicobacter, Flavobacterium, Fusobacterium, Ilyobacter, Neisseria , or Ureaplasma polypeptide having enzyme activity.
In one aspect, the polypeptide is a Bacillus alkalophilus, Bacillus amyloliquefaciens, Bacillus brevis, Bacillus circulans, Bacillus clausii, Bacillus coagulans, Bacillus firmus, Bacillus lautus, Bacillus lentus, Bacillus licheniformis, Bacillus megaterium, Bacillus pumilus, Bacillus stearothermophilus, Bacillus subtilis , or Bacillus thuringiensis polypeptide having enzyme activity.
In another aspect, the polypeptide is a Streptococcus equisimilis, Streptococcus pyogenes, Streptococcus uberis , or Streptococcus equi subsp. Zooepidemicus polypeptide having enzyme activity.
In another aspect, the polypeptide is a Streptomyces achromogenes, Streptomyces avermitilis, Streptomyces coelicolor, Streptomyces griseus , or Streptomyces lividans polypeptide having enzyme activity.
The polypeptide having enzyme activity may also be a fungal polypeptide, and more preferably a yeast polypeptide such as a Candida, Kluyveromyces, Pichia, Saccharomyces, Schizosaccharomyces , or Yarrowia polypeptide having enzyme activity; or more preferably a filamentous fungal polypeptide such as an Acremonium, Agaricus, Alternaria, Aspergillus, Aureobasidium, Botryosphaeria, Ceriporiopsis, Chaetomidium, Chrysosporium, Claviceps, Cochliobolus, Coprinopsis, Coptotermes, Corynascus, Cryphonectria, Cryptococcus, Diplodia, Exidia, Filibasidium, Fusarium, Gibberella, Holomastigotoides, Humicola, Irpex, Lentinula, Leptospaeria, Magnaporthe, Melanocarpus, Meripilus, Mucor, Myceliophthora, Neocallimastix, Neurospora, Paecilomyces, Penicillium, Phanerochaete, Piromyces, Poitrasia, Pseudoplectania, Pseudotrichonympha, Rhizomucor, Schizophyllum, Scytalidium, Talaromyces, Thermoascus, Thielavia, Tolypocladium, Trichoderma, Trichophaea, Verticillium, Volvariella , or Xylaria polypeptide having enzyme activity.
In one aspect, the polypeptide is a Saccharomyces carlsbergensis, Saccharomyces cerevisiae, Saccharomyces diastaticus, Saccharomyces douglasii, Saccharomyces kluyveri, Saccharomyces norbensis , or Saccharomyces oviformis polypeptide having enzyme activity.
In another aspect, the polypeptide is an Acremonium cellulolyticus, Aspergillus aculeatus, Aspergillus awamori, Aspergillus fumigatus, Aspergillus foetidus, Aspergillus japonicus, Aspergillus nidulans, Aspergillus niger, Aspergillus oryzae, Chrysosporium keratinophilum, Chrysosporium lucknowense, Chrysosporium tropicum, Chrysosporium merdarium, Chrysosporium inops, Chrysosporium pannicola, Chrysosporium queenslandicum, Chrysosporium zonatum, Fusarium bactridioides, Fusarium cerealis, Fusarium crookwellense, Fusarium culmorum, Fusarium graminearum, Fusarium graminurn, Fusarium heterosporum, Fusarium negundi, Fusarium oxysporum, Fusarium reticulaturn, Fusarium roseum, Fusarium sambucinum, Fusarium sarcochroum, Fusarium sporotrichioides, Fusarium sulphureum, Fusarium torulosum, Fusarium trichothecioides, Fusarium venenatum, Humicola grisea, Humicola insolens, Humicola lanuginosa, Irpex lacteus, Mucor miehei, Myceliophthora thermophila, Neurospora crassa, Penicillium funiculosum, Penicillium purpurogenum, Phanerochaete chrysosporium, Thielavia achromatica, Thielavia albomyces, Thielavia albopilosa, Thielavia australeinsis, Thielavia fimeti, Thielavia microspora, Thielavia ovispora, Thielavia peruviana, Thielavia spededonium, Thielavia setosa, Thielavia subthermophila, Thielavia terrestris, Trichoderma harzianurn, Trichoderma koningii, Trichoderma longibrachiatum, Trichoderma reesei, Trichoderma viride , or Trichophaea saccata polypeptide having enzyme activity.
Chemically modified or protein engineered mutants of polypeptides having enzyme activity may also be used.
One or more (e.g., several) components of the enzyme composition may be a recombinant component, i.e., produced by cloning of a DNA sequence encoding the single component and subsequent cell transformed with the DNA sequence and expressed in a host (see, for example, WO 91/17243 and WO 91/17244). The host can be a heterologous host (enzyme is foreign to host), but the host may under certain conditions also be a homologous host (enzyme is native to host). Monocomponent cellulolytic proteins may also be prepared by purifying such a protein from a fermentation broth.
In one aspect, the one or more (e.g., several) cellulolytic enzymes comprise a commercial cellulolytic enzyme preparation. Examples of commercial cellulolytic enzyme preparations suitable for use in the present invention include, for example, CELLIC® CTec (Novozymes NS), CELLIC® CTec2 (Novozymes NS), CELLIC® CTec3 (Novozymes NS), CELLUCLAST™ (Novozymes NS), NOVOZYM™ 188 (Novozymes NS), SPEZYME™ CP (Genencor Int.), ACCELLERASE™ TRIO (DuPont), FILTRASE® NL (DSM); METHAPLUS® S/L 100 (DSM), ROHAMENT™ 7069 W (Röhm GmbH), or ALTERNAFUEL® CMAX3™ (Dyadic International, Inc.). The cellulolytic enzyme preparation is added in an amount effective from about 0.001 to about 5.0 wt. % of solids, e.g., about 0.025 to about 4.0 wt. % of solids or about 0.005 to about 2.0 wt. % of solids.
Examples of bacterial endoglucanases that can be used in the processes of the present invention, include, but are not limited to, Acidothermus cellulolyticus endoglucanase (WO 91/05039; WO 93/15186; U.S. Pat. No. 5,275,944; WO 96/02551; U.S. Pat. No. 5,536,655; WO 00/70031; WO 05/093050), Erwinia carotovara endoglucanase (Saarilahti et al., 1990 , Gene 90: 9-14), Thermobifida fusca endoglucanase III (WO 05/093050), and Thermobifida fusca endoglucanase V (WO 05/093050).
Examples of fungal endoglucanases that can be used in the present invention, include, but are not limited to, Trichoderma reesei endoglucanase I (Penttila et al., 1986 , Gene 45: 253-263, Trichoderma reesei Cel7B endoglucanase I (GenBank:M15665), Trichoderma reesei endoglucanase II (Saloheimo et al., 1988, Gene 63:11-22), Trichoderma reesei Cel5A endoglucanase II (GenBank:M19373), Trichoderma reesei endoglucanase III (Okada et al., 1988 , Appl. Environ. Microbiol. 64: 555-563, GenBank:AB003694), Trichoderma reesei endoglucanase V (Saloheimo et al., 1994 , Molecular Microbiology 13: 219-228, GenBank:Z33381), Aspergillus aculeatus endoglucanase (Ooi et al., 1990 , Nucleic Acids Research 18: 5884), Aspergillus kawachii endoglucanase (Sakamoto et al., 1995 , Current Genetics 27: 435-439), Fusarium oxysporum endoglucanase (GenBank:L29381), Humicola grisea var. thermoidea endoglucanase (GenBank:AB003107), Melanocarpus albomyces endoglucanase (GenBank:MAL515703), Neurospora crassa endoglucanase (Gen Bank:XM_324477), Humicola insolens endoglucanase V, Myceliophthora thermophila CBS 117.65 endoglucanase, Thermoascus aurantiacus endoglucanase I (GenBank:AF487830), Trichoderma reesei strain No. VTT-D-80133 endoglucanase (GenBank:M15665), and Penicillium pinophilum endoglucanase (WO 2012/062220).
Examples of cellobiohydrolases useful in the present invention include, but are not limited to, Aspergillus aculeatus cellobiohydrolase II (WO 2011/059740), Aspergillus fumigatus cellobiohydrolase I (WO 2013/028928), Aspergillus fumigatus cellobiohydrolase II (WO 2013/028928), Chaetomium thermophilum cellobiohydrolase I, Chaetomium thermophilum cellobiohydrolase II, Humicola insolens cellobiohydrolase I, Myceliophthora thermophila cellobiohydrolase II (WO 2009/042871), Penicillium occitanis cellobiohydrolase I (GenBank:AY690482), Talaromyces emersonii cellobiohydrolase I (GenBank:AF439936), Thielavia hyrcanie cellobiohydrolase II (WO 2010/141325), Thielavia terrestris cellobiohydrolase II (CEL6A, WO 2006/074435), Trichoderma reesei cellobiohydrolase I, Trichoderma reesei cellobiohydrolase II, and Trichophaea saccata cellobiohydrolase II (WO 2010/057086).
Examples of beta-glucosidases useful in the present invention include, but are not limited to, beta-glucosidases from Aspergillus aculeatus (Kawaguchi et al., 1996 , Gene 173: 287-288), Aspergillus fumigatus (WO 2005/047499), Aspergillus niger (Dan et al., 2000 , J. Biol. Chem. 275: 4973-4980), Aspergillus oryzae (WO 02/095014), Penicillium brasilianum IBT 20888 (WO 2007/019442 and WO 2010/088387), Thielavia terrestris (WO 2011/035029), and Trichophaea saccata (WO 2007/019442).
The beta-glucosidase may be a fusion protein. In one aspect, the beta-glucosidase is an Aspergillus oryzae beta-glucosidase variant BG fusion protein (WO 2008/057637) or an Aspergillus oryzae beta-glucosidase fusion protein (WO 2008/057637).
Other useful endoglucanases, cellobiohydrolases, and beta-glucosidases are disclosed in numerous Glycosyl Hydrolase families using the classification according to Henrissat, 1991 , Biochem. J. 280: 309-316, and Henrissat and Bairoch, 1996 , Biochem. J. 316: 695-696.
Other cellulolytic enzymes that may be used in the present invention are described in WO 98/13465, WO 98/015619, WO 98/015633, WO 99/06574, WO 99/10481, WO 99/025847, WO 99/031255, WO 2002/101078, WO 2003/027306, WO 2003/052054, WO 2003/052055, WO 2003/052056, WO 2003/052057, WO 2003/052118, WO 2004/016760, WO 2004/043980, WO 2004/048592, WO 2005/001065, WO 2005/028636, WO 2005/093050, WO 2005/093073, WO 2006/074005, WO 2006/117432, WO 2007/071818, WO 2007/071820, WO 2008/008070, WO 2008/008793, U.S. Pat. No. 5,457,046, U.S. Pat. No. 5,648,263, and U.S. Pat. No. 5,686,593.
In the processes of the present invention, any GH61 polypeptide having cellulolytic enhancing activity can be used as a component of the enzyme composition.
Examples of GH61 polypeptides useful in the processes of the present invention include, but are not limited to, GH61 polypeptides from Thielavia terrestris (WO 2005/074647, WO 2008/148131, and WO 2011/035027), Thermoascus aurantiacus (WO 2005/074656 and WO 2010/065830), Trichoderma reesei (WO 2007/089290 and WO 2012/149344), Myceliophthora thermophila (WO 2009/085935, WO 2009/085859, WO 2009/085864, WO 2009/085868, and WO 2009/033071), Aspergillus fumigatus (WO 2010/138754), Penicillium pinophilum (WO 2011/005867), Thermoascus sp. (WO 2011/039319), Penicillium sp. ( emersonii ) (WO 2011/041397 and WO 2012/000892), Thermoascus crustaceous (WO 2011/041504), Aspergillus aculeatus (WO 2012/125925), Thermomyces lanuginosus (WO 2012/113340, WO 2012/129699, WO 2012/130964, and WO 2012/129699), Aurantiporus alborubescens (WO 2012/122477), Trichophaea saccata (WO 2012/122477), Penicillium thomii (WO 2012/122477), Talaromyces stipitatus (WO 2012/135659), Humicola insolens (WO 2012/146171), Malbranchea cinnamomea (WO 2012/101206), Talaromyces leycettanus (WO 2012/101206), and Chaetomium thermophilum (WO 2012/101206), and Talaromyces thermophilus (WO 2012/129697 and WO 2012/130950).
In one aspect, the GH61 polypeptide having cellulolytic enhancing activity is used in the presence of a soluble activating divalent metal cation according to WO 2008/151043, e.g., manganese or copper.
In another aspect, the GH61 polypeptide having cellulolytic enhancing activity is used in the presence of a dioxy compound, a bicylic compound, a heterocyclic compound, a nitrogen-containing compound, a quinone compound, a sulfur-containing compound, or a liquor obtained from a pretreated cellulosic material such as pretreated corn stover (WO 2012/021394, WO 2012/021395, WO 2012/021396, WO 2012/021399, WO 2012/021400, WO 2012/021401, WO 2012/021408, and WO 2012/021410).
The dioxy compound may include any suitable compound containing two or more oxygen atoms. In some aspects, the dioxy compounds contain a substituted aryl moiety as described herein. The dioxy compounds may comprise one or more (e.g., several) hydroxyl and/or hydroxyl derivatives, but also include substituted aryl moieties lacking hydroxyl and hydroxyl derivatives. Non-limiting examples of the dioxy compounds include pyrocatechol or catechol; caffeic acid; 3,4-dihydroxybenzoic acid; 4-tert-butyl-5-methoxy-1,2-benzenediol; pyrogallol; gallic acid; methyl-3,4,5-trihydroxybenzoate; 2,3,4-trihydroxybenzophenone; 2,6-dimethoxyphenol; sinapinic acid; 3,5-dihydroxybenzoic acid; 4-chloro-1,2-benzenediol; 4-nitro-1,2-benzenediol; tannic acid; ethyl gallate; methyl glycolate; dihydroxyfumaric acid; 2-butyne-1,4-diol; (croconic acid; 1,3-propanediol; tartaric acid; 2,4-pentanediol; 3-ethyoxy-1,2-propanediol; 2,4,4′-trihydroxybenzophenone; cis-2-butene-1,4-diol; 3,4-dihydroxy-3-cyclobutene-1,2-dione; dihydroxyacetone; acrolein acetal; methyl-4-hydroxybenzoate; 4-hydroxybenzoic acid; and methyl-3,5-dimethoxy-4-hydroxybenzoate; or a salt or solvate thereof.
The bicyclic compound may include any suitable substituted fused ring system as described herein. The compounds may comprise one or more (e.g., several) additional rings, and are not limited to a specific number of rings unless otherwise stated. In one aspect, the bicyclic compound is a flavonoid. In another aspect, the bicyclic compound is an optionally substituted isoflavonoid. In another aspect, the bicyclic compound is an optionally substituted flavylium ion, such as an optionally substituted anthocyanidin or optionally substituted anthocyanin, or derivative thereof. Non-limiting examples of the bicyclic compounds include epicatechin; quercetin; myricetin; taxifolin; kaempferol; morin; acacetin; naringenin; isorhamnetin; apigenin; cyanidin; cyanin; kuromanin; keracyanin; or a salt or solvate thereof.
The heterocyclic compound may be any suitable compound, such as an optionally substituted aromatic or non-aromatic ring comprising a heteroatom, as described herein. In one aspect, the heterocyclic is a compound comprising an optionally substituted heterocycloalkyl moiety or an optionally substituted heteroaryl moiety. In another aspect, the optionally substituted heterocycloalkyl moiety or optionally substituted heteroaryl moiety is an optionally substituted 5-membered heterocycloalkyl or an optionally substituted 5-membered heteroaryl moiety. In another aspect, the optionally substituted heterocycloalkyl or optionally substituted heteroaryl moiety is an optionally substituted moiety selected from pyrazolyl, furanyl, imidazolyl, isoxazolyl, oxadiazolyl, oxazolyl, pyrrolyl, pyridyl, pyrimidyl, pyridazinyl, thiazolyl, triazolyl, thienyl, dihydrothieno-pyrazolyl, thianaphthenyl, carbazolyl, benzimidazolyl, benzothienyl, benzofuranyl, indolyl, quinolinyl, benzotriazolyl, benzothiazolyl, benzooxazolyl, benzimidazolyl, isoquinolinyl, isoindolyl, acridinyl, benzoisazolyl, dimethylhydantoin, pyrazinyl, tetrahydrofuranyl, pyrrolinyl, pyrrolidinyl, morpholinyl, indolyl, diazepinyl, azepinyl, thiepinyl, piperidinyl, and oxepinyl. In another aspect, the optionally substituted heterocycloalkyl moiety or optionally substituted heteroaryl moiety is an optionally substituted furanyl. Non-limiting examples of the heterocyclic compounds include (1,2-dihydroxyethyl)-3,4-dihydroxyfuran-2(5H)-one; 4-hydroxy-5-methyl-3-furanone; 5-hydroxy-2(5H)-furanone; [1,2-dihydroxyethyl]furan-2,3,4(5H)-trione; α-hydroxy-γ-butyrolactone; ribonic γ-lactone; aldohexuronicaldohexuronic acid γ-lactone; gluconic acid δ-lactone; 4-hydroxycoumarin; dihydrobenzofuran; 5-(hydroxymethyl)furfural; furoin; 2(5H)-furanone; 5,6-dihydro-2H-pyran-2-one; and 5,6-dihydro-4-hydroxy-6-methyl-2H-pyran-2-one; or a salt or solvate thereof.
The nitrogen-containing compound may be any suitable compound with one or more nitrogen atoms. In one aspect, the nitrogen-containing compound comprises an amine, imine, hydroxylamine, or nitroxide moiety. Non-limiting examples of the nitrogen-containing compounds include acetone oxime; violuric acid; pyridine-2-aldoxime; 2-aminophenol; 1,2-benzenediamine; 2,2,6,6-tetramethyl-1-piperidinyloxy; 5,6,7,8-tetrahydrobiopterin; 6,7-dimethyl-5,6,7,8-tetrahydropterine; and maleamic acid; or a salt or solvate thereof.
The quinone compound may be any suitable compound comprising a quinone moiety as described herein. Non-limiting examples of the quinone compounds include 1,4-benzoquinone; 1,4-naphthoquinone; 2-hydroxy-1,4-naphthoquinone; 2,3-dimethoxy-5-methyl-1,4-benzoquinone or coenzyme Q 0 ; 2,3,5,6-tetramethyl-1,4-benzoquinone or duroquinone; 1,4-dihydroxyanthraquinone; 3-hydroxy-1-methyl-5,6-indolinedione or adrenochrome; 4-tert-butyl-5-methoxy-1,2-benzoquinone; pyrroloquinoline quinone; or a salt or solvate thereof.
The sulfur-containing compound may be any suitable compound comprising one or more sulfur atoms. In one aspect, the sulfur-containing comprises a moiety selected from thionyl, thioether, sulfinyl, sulfonyl, sulfamide, sulfonamide, sulfonic acid, and sulfonic ester. Non-limiting examples of the sulfur-containing compounds include ethanethiol; 2-propanethiol; 2-propene-1-thiol; 2-mercaptoethanesulfonic acid; benzenethiol; benzene-1,2-dithiol; cysteine; methionine; glutathione; cystine; or a salt or solvate thereof.
In one aspect, an effective amount of such a compound described above is added to cellulosic material at a molar ratio of the compound to glucosyl units of cellulose of about 10 −6 to about 10, e.g., about 10 −6 to about 7.5, about 10 −6 to about 5, about 10 −6 to about 2.5, about 10 −6 to about 1, about 10 −5 to about 1, about 10 −5 to about 10 −1 , about 10 −4 to about 10 −1 , about 10 −3 to about 10 −1 , or about 10 −3 to about 10 −2 . In another aspect, an effective amount of such a compound is about 0.1 μM to about 1 M, e.g., about 0.5 μM to about 0.75 M, about 0.75 μM to about 0.5 M, about 1 μM to about 0.25 M, about 1 μM to about 0.1 M, about 5 μM to about 50 mM, about 10 μM to about 25 mM, about 50 μM to about 25 mM, about 10 μM to about 10 mM, about 5 μM to about 5 mM, or about 0.1 mM to about 1 mM.
The term “liquor” means the solution phase, either aqueous, organic, or a combination thereof, arising from treatment of a lignocellulose and/or hemicellulose material in a slurry, or monosaccharides thereof, e.g., xylose, arabinose, mannose, etc., under conditions as described in WO 2012/021401, and the soluble contents thereof. A liquor for cellulolytic enhancement of a GH61 polypeptide can be produced by treating a lignocellulose or hemicellulose material (or feedstock) by applying heat and/or pressure, optionally in the presence of a catalyst, e.g., acid, optionally in the presence of an organic solvent, and optionally in combination with physical disruption of the material, and then separating the solution from the residual solids. Such conditions determine the degree of cellulolytic enhancement obtainable through the combination of liquor and a GH61 polypeptide during hydrolysis of a cellulosic substrate by a cellulolytic enzyme preparation. The liquor can be separated from the treated material using a method standard in the art, such as filtration, sedimentation, or centrifugation.
In one aspect, an effective amount of the liquor to cellulose is about 10 −6 to about 10 g per g of cellulose, e.g., about 10 −6 to about 7.5 g, about 10 −6 to about 5 g, about 10 −6 to about 2.5 g, about 10 −6 to about 1 g, about 10 −5 to about 1 g, about 10 −5 to about 10 −1 g, about 10 −4 to about 10 −1 g, about 10 −3 to about 10 −1 g, or about 10 −3 to about 10 −2 g per g of cellulose.
In one aspect, the one or more (e.g., several) hemicellulolytic enzymes comprise a commercial hemicellulolytic enzyme preparation. Examples of commercial hemicellulolytic enzyme preparations suitable for use in the present invention include, for example, SHEARZYME™ (Novozymes NS), CELLIC® HTec (Novozymes NS), CELLIC® HTec2 (Novozymes NS), CELLIC® HTec3 (Novozymes NS), VISCOZYME® (Novozymes NS), ULTRAFLO® (Novozymes NS), PULPZYME® HC (Novozymes NS), MULTIFECT® Xylanase (Genencor), ACCELLERASE® XY (Genencor), ACCELLERASE® XC (Genencor), ECOPULP® TX-200A (AB Enzymes), HSP 6000 Xylanase (DSM), DEPOL™ 333P (Biocatalysts Limit, Wales, UK), DEPOL™ 740L. (Biocatalysts Limit, Wales, UK), and DEPOL™ 762P (Biocatalysts Limit, Wales, UK), ALTERNA FUEL 100P (Dyadic), and ALTERNA FUEL 200P (Dyadic).
Examples of xylanases useful in the processes of the present invention include, but are not limited to, xylanases from Aspergillus aculeatus (GeneSeqP:AAR63790; WO 94/21785), Aspergillus fumigatus (WO 2006/078256), Penicillium pinophilum (WO 2011/041405), Penicillium sp. (WO 2010/126772), Thermomyces lanuginosus (GeneSeqP:BAA22485), Talaromyces thermophilus (GeneSeqP:BAA22834), Thielavia terrestris NRRL 8126 (WO 2009/079210), and Trichophaea saccata (WO 2011/057083).
Examples of beta-xylosidases useful in the processes of the present invention include, but are not limited to, beta-xylosidases from Neurospora crassa (SwissProt:Q7SOW4), Trichoderma reesei (UniProtKB/TrEMBL:Q92458), Talaromyces emersonii (SwissProt:Q8X212), and Talaromyces thermophilus (GeneSeqP:BAA22816).
Examples of acetylxylan esterases useful in the processes of the present invention include, but are not limited to, acetylxylan esterases from Aspergillus aculeatus (WO 2010/108918), Chaetomium globosum (UniProt:Q2GWX4), Chaetomium gracile (GeneSeqP:AAB82124), Humicola insolens DSM 1800 (WO 2009/073709), Hypocrea jecorina (WO 2005/001036), Myceliophtera thermophila (WO 2010/014880), Neurospora crassa (UniProt:q7s259), Phaeosphaeria nodorum (UniProt:Q0UHJ1), and Thielavia terrestris NRRL 8126 (WO 2009/042846).
Examples of feruloyl esterases (ferulic acid esterases) useful in the processes of the present invention include, but are not limited to, feruloyl esterases form Humicola insolens DSM 1800 (WO 2009/076122), Neosartorya fischeri (UniProt:A1 D9T4), Neurospora crassa (UniProt:Q9HGR3), Penicillium aurantiogriseum (WO 2009/127729), and Thielavia terrestris (WO 2010/053838 and WO 2010/065448).
Examples of arabinofuranosidases useful in the processes of the present invention include, but are not limited to, arabinofuranosidases from Aspergillus niger (GeneSeqP:AAR94170), Humicola insolens DSM 1800 (WO 2006/114094 and WO 2009/073383), and M. giganteus (WO 2006/114094).
Examples of alpha-glucuronidases useful in the processes of the present invention include, but are not limited to, alpha-glucuronidases from Aspergillus clavatus (UniProt:alcc12), Aspergillus fumigatus (SwissProt:Q4WW45), Aspergillus niger (UniProt:Q96WX9), Aspergillus terreus (SwissProt:Q0CJ P9), Humicola insolens (WO 2010/014706), Penicillium aurantiogriseum (WO 2009/068565), Talaromyces emersonii (UniProt:Q8X211), and Trichoderma reesei (UniProt:Q99024).
Examples of oxidoreductases useful in the processes of the present invention include, but are not limited to, Aspergillus fumigatus catalase, Aspergillus lentilus catalase, Aspergillus niger catalase, Aspergillus oryzae catalase, Humicola insolens catalase, Neurospora crassa catalase, Penicillium emersonii catalase, Scytalidium thermophilum catalase, Talaromyces stipitatus catalase, Thermoascus aurantiacus catalase, Coprinus cinereus laccase, Myceliophthora thermophila laccase, Polyporus pinsitus laccase, Pycnoporus cinnabarinus laccase, Rhizoctonia solani laccase, Streptomyces coelicolor laccase, Coprinus cinereus peroxidase, Soy peroxidase, and Royal palm peroxidase.
The polypeptides having enzyme activity used in the processes of the present invention may be produced by fermentation of the above-noted microbial strains on a nutrient medium containing suitable carbon and nitrogen sources and inorganic salts, using procedures known in the art (see, e.g., Bennett, J. W. and LaSure, L. (eds.), More Gene Manipulations in Fungi , Academic Press, CA, 1991). Suitable media are available from commercial suppliers or may be prepared according to published compositions (e.g., in catalogues of the American Type Culture Collection). Temperature ranges and other conditions suitable for growth and enzyme production are known in the art (see, e.g., Bailey, J. E., and Ollis, D. F., Biochemical Engineering Fundamentals , McGraw-Hill Book Company, NY, 1986).
The fermentation can be any method of cultivation of a cell resulting in the expression or isolation of an enzyme or protein. Fermentation may, therefore, be understood as comprising shake flask cultivation, or small- or large-scale fermentation (including continuous, batch, fed-batch, or solid state fermentations) in laboratory or industrial fermentors performed in a suitable medium and under conditions allowing the enzyme to be expressed or isolated. The resulting enzymes produced by the methods described above may be recovered from the fermentation medium and purified by conventional procedures.
Fermentation.
The fermentable sugars obtained from the hydrolyzed cellulosic material can be fermented by one or more (e.g., several) fermenting microorganisms capable of fermenting the sugars directly or indirectly into a desired fermentation product. “Fermentation” or “fermentation process” refers to any fermentation process or any process comprising a fermentation step. Fermentation processes also include fermentation processes used in the consumable alcohol industry (e.g., beer and wine), dairy industry (e.g., fermented dairy products), leather industry, and tobacco industry. The fermentation conditions depend on the desired fermentation product and fermenting organism and can easily be determined by one skilled in the art.
In the fermentation step, sugars, released from the cellulosic material as a result of the pretreatment and enzymatic hydrolysis steps, are fermented to a product, e.g., ethanol, by a fermenting organism, such as yeast. Hydrolysis (saccharification) and fermentation can be separate or simultaneous.
Any suitable hydrolyzed cellulosic material can be used in the fermentation step in practicing the present invention. The material is generally selected based on economics, i.e., costs per equivalent sugar potential, and recalcitrance to enzymatic conversion.
The term “fermentation medium” is understood herein to refer to a medium before the fermenting microorganism(s) is(are) added, such as, a medium resulting from a saccharification process, as well as a medium used in a simultaneous saccharification and fermentation process (SSF).
“Fermenting microorganism” refers to any microorganism, including bacterial and fungal organisms, suitable for use in a desired fermentation process to produce a fermentation product. The fermenting organism can be hexose and/or pentose fermenting organisms, or a combination thereof. Both hexose and pentose fermenting organisms are well known in the art. Suitable fermenting microorganisms are able to ferment, i.e., convert, sugars, such as glucose, xylose, xylulose, arabinose, maltose, mannose, galactose, and/or oligosaccharides, directly or indirectly into the desired fermentation product. Examples of bacterial and fungal fermenting organisms producing ethanol are described by Lin et al., 2006 , Appl. Microbiol. Biotechnol. 69: 627-642.
Examples of fermenting microorganisms that can ferment hexose sugars include bacterial and fungal organisms, such as yeast. Yeast include strains of Candida, Kluyveromyces , and Saccharomyces , e.g., Candida sonorensis, Kluyveromyces marxianus , and Saccharomyces cerevisiae.
Examples of fermenting organisms that can ferment pentose sugars in their native state include bacterial and fungal organisms, such as some yeast. Xylose fermenting yeast include strains of Candida , preferably C. sheatae or C. sonorensis ; and strains of Pichia , e.g., P. stipitis , such as P. stipitis CBS 5773. Pentose fermenting yeast include strains of Pachysolen , preferably P. tannophilus . Organisms not capable of fermenting pentose sugars, such as xylose and arabinose, may be genetically modified to do so by methods known in the art.
Examples of bacteria that can efficiently ferment hexose and pentose to ethanol include, for example, Bacillus coagulans, Clostridium acetobutylicum, Clostridium thermocellum, Clostridium phytofermentans, Geobacillus sp., Thermoanaerobacter saccharolyticum , and Zymomonas mobilis (Philippidis, G. P., 1996, Cellulose bioconversion technology, in Handbook on Bioethanol: Production and Utilization , Wyman, C. E., ed., Taylor & Francis, Washington, D.C., 179-212).
Other fermenting organisms include strains of Bacillus , such as Bacillus coagulans; Candida , such as C. sonorensis, C. methanosorbosa, C. diddensiae, C. parapsilosis, C. naedodendra, C. blankii, C. entomophilia, C. brassicae, C. pseudotropicalis, C. boidinii, C. utilis , and C. scehatae; Clostridium , such as C. acetobutylicum, C. thermocellum , and C. phytofermentans; E. coli , especially E. coli strains that have been genetically modified to improve the yield of ethanol; Geobacillus sp.; Hansenula , such as Hansenula anomala; Klebsiella , such as K. oxytoca; Kluyveromyces , such as K. marxianus, K. lactis, K. thermotolerans , and K. fragilis; Schizosaccharomyces , such as S. pombe; Thermoanaerobacter , such as Thermoanaerobacter saccharolyticum ; and Zymomonas , such as Zymomonas mobilis.
Commercially available yeast suitable for ethanol production include, e.g., BIOFERM™ AFT and XR (NABC—North American Bioproducts Corporation, GA, USA), ETHANOL RED™ yeast (Fermentis/Lesaffre, USA), FALI™ (Fleischmann's Yeast, USA), FERMIOL™ (DSM Specialties), GERT STRAND™ (Gert Strand AB, Sweden), and SUPERSTART™ and THERMOSACC™ fresh yeast (Ethanol Technology, WI, USA).
In an aspect, the fermenting microorganism has been genetically modified to provide the ability to ferment pentose sugars, such as xylose utilizing, arabinose utilizing, and xylose and arabinose co-utilizing microorganisms.
The cloning of heterologous genes into various fermenting microorganisms has led to the construction of organisms capable of converting hexoses and pentoses to ethanol (co-fermentation) (Chen and Ho, 1993 , Appl. Biochem. Biotechnol. 39-40: 135-147; Ho et al., 1998 , Appl. Environ. Microbiol. 64: 1852-1859; Kotter and Ciriacy, 1993 , Appl. Microbiol. Biotechnol. 38: 776-783; Walfridsson et al., 1995 , Appl. Environ. Microbiol. 61: 4184-4190; Kuyper et al., 2004 , FEMS Yeast Research 4: 655-664; Beall et al., 1991 , Biotech. Bioeng. 38: 296-303; Ingram et al., 1998 , Biotechnol. Bioeng. 58: 204-214; Zhang et al., 1995 , Science 267: 240-243; Deanda et al., 1996 , Appl. Environ. Microbiol. 62: 4465-4470; WO 03/062430).
In one aspect, the fermenting organism comprises a polynucleotide encoding a variant of the present invention.
In another aspect, the fermenting organism comprises one or more polynucleotides encoding one or more cellulolytic enzymes, hemicellulolytic enzymes, and accessory enzymes described herein.
It is well known in the art that the organisms described above can also be used to produce other substances, as described herein.
The fermenting microorganism is typically added to the degraded cellulosic material or hydrolysate and the fermentation is performed for about 8 to about 96 hours, e.g., about 24 to about 60 hours. The temperature is typically between about 26° C. to about 60° C., e.g., about 32° C. or 50° C., and about pH 3 to about pH 8, e.g., pH 4-5, 6, or 7.
In one aspect, the yeast and/or another microorganism are applied to the degraded cellulosic material and the fermentation is performed for about 12 to about 96 hours, such as typically 24-60 hours. In another aspect, the temperature is preferably between about 20° C. to about 60° C., e.g., about 25° C. to about 50° C., about 32° C. to about 50° C., or about 32° C. to about 50° C., and the pH is generally from about pH 3 to about pH 7, e.g., about pH 4 to about pH 7. However, some fermenting organisms, e.g., bacteria, have higher fermentation temperature optima. Yeast or another microorganism is preferably applied in amounts of approximately 10 5 to 10 12 , preferably from approximately 10 7 to 10 10 , especially approximately 2×10 8 viable cell count per ml of fermentation broth. Further guidance in respect of using yeast for fermentation can be found in, e.g., “The Alcohol Textbook” (Editors K. Jacques, T. P. Lyons and D. R. Kelsall, Nottingham University Press, United Kingdom 1999), which is hereby incorporated by reference.
A fermentation stimulator can be used in combination with any of the processes described herein to further improve the fermentation process, and in particular, the performance of the fermenting microorganism, such as, rate enhancement and ethanol yield. A “fermentation stimulator” refers to stimulators for growth of the fermenting microorganisms, in particular, yeast. Preferred fermentation stimulators for growth include vitamins and minerals. Examples of vitamins include multivitamins, biotin, pantothenate, nicotinic acid, meso-inositol, thiamine, pyridoxine, para-aminobenzoic acid, folic acid, riboflavin, and Vitamins A, B, C, D, and E. See, for example, Alfenore et al., Improving ethanol production and viability of Saccharomyces cerevisiae by a vitamin feeding strategy during fed-batch process, Springer-Verlag (2002), which is hereby incorporated by reference. Examples of minerals include minerals and mineral salts that can supply nutrients comprising P, K, Mg, S, Ca, Fe, Zn, Mn, and Cu.
Fermentation Products:
A fermentation product can be any substance derived from the fermentation. The fermentation product can be, without limitation, an alcohol (e.g., arabinitol, n-butanol, isobutanol, ethanol, glycerol, methanol, ethylene glycol, 1,3-propanediol [propylene glycol], butanediol, glycerin, sorbitol, and xylitol); an alkane (e.g., pentane, hexane, heptane, octane, nonane, decane, undecane, and dodecane), a cycloalkane (e.g., cyclopentane, cyclohexane, cycloheptane, and cyclooctane), an alkene (e.g. pentene, hexene, heptene, and octene); an amino acid (e.g., aspartic acid, glutamic acid, glycine, lysine, serine, and threonine); a gas (e.g., methane, hydrogen (H 2 ), carbon dioxide (CO 2 ), and carbon monoxide (CO)); isoprene; a ketone (e.g., acetone); an organic acid (e.g., acetic acid, acetonic acid, adipic acid, ascorbic acid, citric acid, 2,5-diketo-D-gluconic acid, formic acid, fumaric acid, glucaric acid, gluconic acid, glucuronic acid, glutaric acid, 3-hydroxypropionic acid, itaconic acid, lactic acid, malic acid, malonic acid, oxalic acid, oxaloacetic acid, propionic acid, succinic acid, and xylonic acid); and polyketide.
In one aspect, the fermentation product is an alcohol. The term “alcohol” encompasses a substance that contains one or more hydroxyl moieties. The alcohol can be, but is not limited to, n-butanol, isobutanol, ethanol, methanol, arabinitol, butanediol, ethylene glycol, glycerin, glycerol, 1,3-propanediol, sorbitol, xylitol. See, for example, Gong et al., 1999, Ethanol production from renewable resources, in Advances in Biochemical Engineering/Biotechnology , Scheper, T., ed., Springer-Verlag Berlin Heidelberg, Germany, 65: 207-241; Silveira and Jonas, 2002 , Appl. Microbiol. Biotechnol. 59: 400-408; Nigam and Singh, 1995 , Process Biochemistry 30(2): 117-124; Ezeji et al., 2003 , World Journal of Microbiology and Biotechnology 19(6): 595-603.
In another aspect, the fermentation product is an alkane. The alkane may be an unbranched or a branched alkane. The alkane can be, but is not limited to, pentane, hexane, heptane, octane, nonane, decane, undecane, or dodecane.
In another aspect, the fermentation product is a cycloalkane. The cycloalkane can be, but is not limited to, cyclopentane, cyclohexane, cycloheptane, or cyclooctane.
In another aspect, the fermentation product is an alkene. The alkene may be an unbranched or a branched alkene. The alkene can be, but is not limited to, pentene, hexene, heptene, or octene.
In another aspect, the fermentation product is an amino acid. The organic acid can be, but is not limited to, aspartic acid, glutamic acid, glycine, lysine, serine, or threonine. See, for example, Richard and Margaritis, 2004 , Biotechnology and Bioengineering 87(4): 501-515.
In another aspect, the fermentation product is a gas. The gas can be, but is not limited to, methane, H 2 , CO 2 , or CO. See, for example, Kataoka et al., 1997 , Water Science and Technology 36(6-7): 41-47; and Gunaseelan, 1997 , Biomass and Bioenergy 13(1-2): 83-114.
In another aspect, the fermentation product is isoprene.
In another aspect, the fermentation product is a ketone. The term “ketone” encompasses a substance that contains one or more ketone moieties. The ketone can be, but is not limited to, acetone.
In another aspect, the fermentation product is an organic acid. The organic acid can be, but is not limited to, acetic acid, acetonic acid, adipic acid, ascorbic acid, citric acid, 2,5-diketo-D-gluconic acid, formic acid, fumaric acid, glucaric acid, gluconic acid, glucuronic acid, glutaric acid, 3-hydroxypropionic acid, itaconic acid, lactic acid, malic acid, malonic acid, oxalic acid, propionic acid, succinic acid, or xylonic acid. See, for example, Chen and Lee, 1997 , Appl. Biochem. Biotechnol. 63-65: 435-448.
In another aspect, the fermentation product is polyketide.
Recovery.
The fermentation product(s) can be optionally recovered from the fermentation medium using any method known in the art including, but not limited to, chromatography, electrophoretic procedures, differential solubility, distillation, or extraction. For example, alcohol is separated from the fermented cellulosic material and purified by conventional methods of distillation. Ethanol with a purity of up to about 96 vol. % can be obtained, which can be used as, for example, fuel ethanol, drinking ethanol, i.e., potable neutral spirits, or industrial ethanol.
Plants
The present invention also relates to isolated plants, e.g., a transgenic plant, plant part, or plant cell, comprising a polynucleotide of the present invention so as to express and produce a cellobiohydrolase variant in recoverable quantities. The variant may be recovered from the plant or plant part. Alternatively, the plant or plant part containing the variant may be used as such for improving the quality of a food or feed, e.g., improving nutritional value, palatability, and rheological properties, or to destroy an antinutritive factor.
The transgenic plant can be dicotyledonous (a dicot) or monocotyledonous (a monocot). Examples of monocot plants are grasses, such as meadow grass (blue grass, Poa), forage grass such as Festuca, Lolium , temperate grass, such as Agrostis , and cereals, e.g., wheat, oats, rye, barley, rice, sorghum, and maize (corn).
Examples of dicot plants are tobacco, legumes, such as lupins, potato, sugar beet, pea, bean and soybean, and cruciferous plants (family Brassicaceae), such as cauliflower, rape seed, and the closely related model organism Arabidopsis thaliana.
Examples of plant parts are stem, callus, leaves, root, fruits, seeds, and tubers as well as the individual tissues comprising these parts, e.g., epidermis, mesophyll, parenchyme, vascular tissues, meristems. Specific plant cell compartments, such as chloroplasts, apoplasts, mitochondria, vacuoles, peroxisomes and cytoplasm are also considered to be a plant part. Furthermore, any plant cell, whatever the tissue origin, is considered to be a plant part. Likewise, plant parts such as specific tissues and cells isolated to facilitate the utilization of the invention are also considered plant parts, e.g., embryos, endosperms, aleurone and seed coats.
Also included within the scope of the present invention are the progeny of such plants, plant parts, and plant cells.
The transgenic plant or plant cell expressing a variant may be constructed in accordance with methods known in the art. In short, the plant or plant cell is constructed by incorporating one or more expression constructs encoding a variant into the plant host genome or chloroplast genome and propagating the resulting modified plant or plant cell into a transgenic plant or plant cell.
The expression construct is conveniently a nucleic acid construct that comprises a polynucleotide encoding a variant operably linked with appropriate regulatory sequences required for expression of the polynucleotide in the plant or plant part of choice. Furthermore, the expression construct may comprise a selectable marker useful for identifying plant cells into which the expression construct has been integrated and DNA sequences necessary for introduction of the construct into the plant in question (the latter depends on the DNA introduction method to be used).
The choice of regulatory sequences, such as promoter and terminator sequences and optionally signal or transit sequences, is determined, for example, on the basis of when, where, and how the variant is desired to be expressed (Sticklen, 2008 , Nature Reviews 9: 433-443). For instance, the expression of the gene encoding a variant may be constitutive or inducible, or may be developmental, stage or tissue specific, and the gene product may be targeted to a specific tissue or plant part such as seeds or leaves. Regulatory sequences are, for example, described by Tague et al., 1988 , Plant Physiology 86: 506.
For constitutive expression, the 35S-CaMV, the maize ubiquitin 1, or the rice actin 1 promoter may be used (Franck et al., 1980 , Cell 21: 285-294; Christensen et al., 1992 , Plant Mol. Biol. 18: 675-689; Zhang et al., 1991 , Plant Cell 3: 1155-1165). Organ-specific promoters may be, for example, a promoter from storage sink tissues such as seeds, potato tubers, and fruits (Edwards and Coruzzi, 1990 , Ann. Rev. Genet. 24: 275-303), or from metabolic sink tissues such as meristems (Ito et al., 1994 , Plant Mol. Biol. 24: 863-878), a seed specific promoter such as the glutelin, prolamin, globulin, or albumin promoter from rice (Wu et al., 1998 , Plant Cell Physiol. 39: 885-889), a Vicia faba promoter from the legumin B4 and the unknown seed protein gene from Vicia faba (Conrad et al., 1998 , J. Plant Physiol. 152: 708-711), a promoter from a seed oil body protein (Chen et al., 1998 , Plant Cell Physiol. 39: 935-941), the storage protein napA promoter from Brassica napus , or any other seed specific promoter known in the art, e.g., as described in WO 91/14772. Furthermore, the promoter may be a leaf specific promoter such as the rbcs promoter from rice or tomato (Kyozuka et al., 1993 , Plant Physiol. 102: 991-1000), the chlorella virus adenine methyltransferase gene promoter (Mitra and Higgins, 1994 , Plant Mol. Biol. 26: 85-93), the aldP gene promoter from rice (Kagaya et al., 1995 , Mol. Gen. Genet. 248: 668-674), or a wound inducible promoter such as the potato pin2 promoter (Xu et al., 1993 , Plant Mol. Biol. 22: 573-588). Likewise, the promoter may be induced by abiotic treatments such as temperature, drought, or alterations in salinity or induced by exogenously applied substances that activate the promoter, e.g., ethanol, oestrogens, plant hormones such as ethylene, abscisic acid, and gibberellic acid, and heavy metals.
A promoter enhancer element may also be used to achieve higher expression of a variant in the plant. For instance, the promoter enhancer element may be an intron that is placed between the promoter and the polynucleotide encoding a variant. For instance, Xu et al., 1993, supra, disclose the use of the first intron of the rice actin 1 gene to enhance expression.
The selectable marker gene and any other parts of the expression construct may be chosen from those available in the art.
The nucleic acid construct is incorporated into the plant genome according to conventional techniques known in the art, including Agrobacterium -mediated transformation, virus-mediated transformation, microinjection, particle bombardment, biolistic transformation, and electroporation (Gasser et al., 1990 , Science 244: 1293; Potrykus, 1990 , Bio/Technology 8: 535; Shimamoto et al., 1989 , Nature 338: 274).
Agrobacterium tumefaciens -mediated gene transfer is a method for generating transgenic dicots (for a review, see Hooykas and Schilperoort, 1992 , Plant Mol. Biol. 19: 15-38) and for transforming monocots, although other transformation methods may be used for these plants. A method for generating transgenic monocots is particle bombardment (microscopic gold or tungsten particles coated with the transforming DNA) of embryonic calli or developing embryos (Christou, 1992 , Plant J. 2: 275-281; Shimamoto, 1994 , Curr. Opin. Biotechnol. 5: 158-162; Vasil et al., 1992 , Bio/Technology 10: 667-674). An alternative method for transformation of monocots is based on protoplast transformation as described by Omirulleh et al., 1993 , Plant Mol. Biol. 21: 415-428. Additional transformation methods include those described in U.S. Pat. Nos. 6,395,966 and 7,151,204 (both of which are herein incorporated by reference in their entirety).
Following transformation, the transformants having incorporated the expression construct are selected and regenerated into whole plants according to methods well known in the art. Often the transformation procedure is designed for the selective elimination of selection genes either during regeneration or in the following generations by using, for example, co-transformation with two separate T-DNA constructs or site specific excision of the selection gene by a specific recombinase.
In addition to direct transformation of a particular plant genotype with a construct of the present invention, transgenic plants may be made by crossing a plant having the construct to a second plant lacking the construct. For example, a construct encoding a variant can be introduced into a particular plant variety by crossing, without the need for ever directly transforming a plant of that given variety. Therefore, the present invention encompasses not only a plant directly regenerated from cells which have been transformed in accordance with the present invention, but also the progeny of such plants. As used herein, progeny may refer to the offspring of any generation of a parent plant prepared in accordance with the present invention. Such progeny may include a DNA construct prepared in accordance with the present invention. Crossing results in the introduction of a transgene into a plant line by cross pollinating a starting line with a donor plant line. Non-limiting examples of such steps are described in U.S. Pat. No. 7,151,204.
Plants may be generated through a process of backcross conversion. For example, plants include plants referred to as a backcross converted genotype, line, inbred, or hybrid.
Genetic markers may be used to assist in the introgression of one or more transgenes of the invention from one genetic background into another. Marker assisted selection offers advantages relative to conventional breeding in that it can be used to avoid errors caused by phenotypic variations. Further, genetic markers may provide data regarding the relative degree of elite germplasm in the individual progeny of a particular cross. For example, when a plant with a desired trait which otherwise has a non-agronomically desirable genetic background is crossed to an elite parent, genetic markers may be used to select progeny which not only possess the trait of interest, but also have a relatively large proportion of the desired germplasm. In this way, the number of generations required to introgress one or more traits into a particular genetic background is minimized.
The present invention also relates to methods of producing a variant of the present invention comprising: (a) cultivating a transgenic plant or a plant cell comprising a polynucleotide encoding the variant under conditions conducive for production of the variant; and optionally (b) recovering the variant.
The present invention may be further described by the following numbered paragraphs:
[1] A cellobiohydrolase variant, comprising deletions at two or more consecutive positions corresponding to positions of the B2-loop, wherein the variant has cellobiohydrolase activity, and wherein the variant has at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100%, sequence identity to the mature polypeptide of a parent cellobiohydrolase.
[2] A cellobiohydrolase variant, comprising a deletion at one or more positions corresponding to positions 195, 196, 197, and 198 of SEQ ID NO: 2, wherein the variant has cellobiohydrolase activity, and wherein the variant has at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100%, sequence identity to the mature polypeptide of a parent cellobiohydrolase.
[3] The variant of paragraph 1 or 2, wherein the parent cellobiohydrolase is selected from the group consisting of: (a) a polypeptide having at least 60% sequence identity to the mature polypeptide of SEQ ID NO: 2, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 14, SEQ ID NO: 16, SEQ ID NO: 18, SEQ ID NO: 20, or SEQ ID NO: 22; (b) a polypeptide encoded by a polynucleotide that hybridizes under low stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, or SEQ ID NO: 21; or the full-length complement thereof; (c) a polypeptide encoded by a polynucleotide having at least 60% identity to the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, or SEQ ID NO: 21; and (d) a fragment of the mature polypeptide of SEQ ID NO: 2, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 14, SEQ ID NO: 16, SEQ ID NO: 18, SEQ ID NO: 20, or SEQ ID NO: 22, which has cellobiohydrolase activity.
[4] The variant of paragraph 3, wherein the parent cellobiohydrolase has at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% sequence identity to the mature polypeptide of SEQ ID NO: 2, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 14, SEQ ID NO: 16, SEQ ID NO: 18, SEQ ID NO: 20, or SEQ ID NO: 22.
[5] The variant of paragraph 3 or 4, wherein the parent cellobiohydrolase is encoded by a polynucleotide that hybridizes under low stringency conditions, medium stringency conditions, medium-high stringency conditions, high stringency conditions, or very high stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, or SEQ ID NO: 21; or the full-length complement thereof.
[6] The variant of any of paragraphs 3-5, wherein the parent cellobiohydrolase is encoded by a polynucleotide having at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, or SEQ ID NO: 21.
[7] The variant of any of paragraphs 3-6, wherein the parent cellobiohydrolase comprises or consists of the mature polypeptide of SEQ ID NO: 2, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 14, SEQ ID NO: 16, SEQ ID NO: 18, SEQ ID NO: 20, or SEQ ID NO: 22.
[8] The variant of any of paragraphs 3-7, wherein the parent cellobiohydrolase is a fragment of the mature polypeptide of SEQ ID NO: 2, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 14, SEQ ID NO: 16, SEQ ID NO: 18, SEQ ID NO: 20, or SEQ ID NO: 22, wherein the fragment has cellobiohydrolase activity.
[9] The variant of any of paragraphs 1-8, which has at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 95% identity, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100%, sequence identity to the amino acid sequence of the parent cellobiohydrolase or the mature polypeptide thereof.
[10] The variant of any of paragraphs 1-9, wherein the number of alterations is 1-7, e.g., 1, 2, 3, 4, 5, 6, and 7 alterations.
[11] The variant of any of paragraphs 1, or 3-10, which comprises deletions at positions corresponding to positions 195 and 196 of SEQ ID NO: 2 (e.g., S195*+S196*, or S195*+A196*).
[12] The variant of any of paragraphs 1, or 3-10, which comprises deletions at positions corresponding to positions 196 and 197 of SEQ ID NO: 2 (e.g., S196*+N197*, or A196*+N197*)
[13] The variant of any of paragraphs 1, or 3-10, which comprises deletions at positions corresponding to positions 197 and 198 of SEQ ID NO: 2 (e.g., N197*+N198*, N197*+D198*).
[14] The variant of any of paragraphs 1, or 3-10, which comprises deletions at positions corresponding to positions 198 and 199 of SEQ ID NO: 2 (e.g., N198*+A199*, D198*+A199*, or D198*+P199*).
[15] The variant of any of paragraphs 1, or 3-10, which comprises deletions at positions corresponding to positions 199 and 200 of SEQ ID NO: 2 (e.g., A199*+N200*, or P199*+N200*).
[16] The variant of any of paragraphs 1, or 3-10, which comprises deletions at positions corresponding to positions 200 and 201 of SEQ ID NO: 2 (e.g., N200*+T201*, N200*+A201*, or N200*+S201*).
[17] The variant of any of paragraphs 1, or 3-10, which comprises deletions at three or more consecutive positions of the B2-loop (e.g., deletions at positions corresponding to positions 194*+195*+196*, 195*+196*+197*, 196*+197*+198*, 197*+198*+199*, 198*+199*+200*, or 199*+200*+201* of SEQ ID NO: 2).
[18] The variant of any of paragraphs 1, or 3-10, which comprises deletions at four or more consecutive positions of the B2-loop (e.g., deletions at positions corresponding to positions 194*+195*+196*+197*, 195*+196*+197*+198*, 196*+197*+198*+199*, 197*+198*+199*+200*, or 198*+199*+200*+201* of SEQ ID NO: 2).
[19] The variant of any of paragraphs 1, or 3-10, which comprises deletions at five or more consecutive positions of the B2-loop (e.g., deletions at positions corresponding to positions 194*+195*+196*+197*+198*, 195*+196*+197*+198*+199*, 196*+197*+198*+199*+200*, or 197*+198*+199*+200*+201* of SEQ ID NO: 2).
[20] The variant of any of paragraphs 1, or 3-10, which comprises deletions at six or more consecutive positions of the B2-loop. (e.g., deletions at positions corresponding to positions 194*+195*+196*+197*+198*+199*, 195*+196*+197*+198*+199*+200*, or 196*+197*+198*+199*+200*+201* of SEQ ID NO: 2).
[21] The variant of any of paragraphs 1, or 3-10, which comprises deletions at seven or more consecutive positions of the B2-loop (e.g., deletions at positions corresponding to positions 194*+195*+196*+197*+198*+199*+200*, or 195*+196*+197*+198*+199*+200*+201* of SEQ ID NO: 2).
[22] The variant of any of paragraphs 1, or 3-10, which comprises deletions at eight consecutive positions of the B2-loop (e.g., deletions at positions corresponding to positions 194*+195*+196*+197*+198*+199*+200*+201* of SEQ ID NO: 2).
[23] The variant of any of paragraphs 2-10, which comprises a deletion at a position corresponding to position 195 of SEQ ID NO: 2 (e.g., an S195* deletion).
[24] The variant of any of paragraphs 2-11, which comprises a deletion at a position corresponding to position 196 of SEQ ID NO: 2 (e.g., an S196* deletion).
[25] The variant of any of paragraphs 2-12, which comprises a deletion at a position corresponding to position 197 of SEQ ID NO: 2 (e.g., an N197* deletion).
[26] The variant of any of paragraphs 2-13, which comprises a deletion at a position corresponding to position 198 of SEQ ID NO: 2 (e.g., an N198* deletion).
[27] The variant of any of paragraphs 2-10, which comprises a deletion at two positions corresponding to any of positions 195, 196, 197, and 198 of SEQ ID NO: 2 (e.g., 195 and 196, such as S195*+S196*; 195 and 197, such as S195*+N197*; 195 and 198, such as S195*+N198*; 196 and 197, such as S196*+N197*; 196 and 198, such as S196*+N198*; or 197 and 198, such as N197*+N198*
[28] The variant of any of paragraphs 2-10, which comprises a deletion at positions corresponding to positions 196, 197, and 198 of SEQ ID NO: 2 (e.g., S196*+N197*+N198*).
[29] The variant of any of paragraphs 2-10, which comprises a deletion at each position corresponding to positions 195, 196, 197, and 198 of SEQ ID NO: 2 (e.g., S195*+S196*+N197*+N198*).
[30] The variant of any of paragraphs 1-29, wherein the variant further comprises an alteration (e.g., a substitution) at one or more positions corresponding to positions 197, 198, and 199 of SEQ ID NO: 2
[31] The variant of any of paragraphs 1-30, wherein the variant further comprises a deletion at a position corresponding to position 200 of SEQ ID NO: 2.
[32] The variant of paragraph 1 or 2, which comprises or consists of amino acids 1-434 of SEQ ID NO: 78, amino acids 1-495 of SEQ ID NO: 80, amino acids 1-495 of SEQ ID NO: 82, or amino acids 1-503 of SEQ ID NO: 95.
[33] The variant of any of paragraphs 1-31, wherein the parent is a hybrid or chimeric polypeptide in which the carbohydrate binding domain of the parent is replaced with a different carbohydrate binding domain.
[34] The variant of any of paragraphs 1-31, which is a hybrid or chimeric polypeptide in which the carbohydrate binding domain of the variant is replaced with a different carbohydrate binding domain.
[35] The variant of any of paragraphs 1-31, wherein the parent is a fusion protein in which a heterologous carbohydrate binding domain is fused to the parent.
[36] The variant of paragraph 35, wherein the carbohydrate binding domain is fused to the N-terminus or the C-terminus of the parent.
[37] The variant of paragraph 35 or 36, wherein the fusion protein comprises or consists of SEQ ID NO: 78 or the mature polypeptide thereof.
[38] The variant of any of paragraphs 1-31, which is a fusion protein in which a heterologous carbohydrate binding domain is fused to the variant.
[39] The variant of paragraph 38, wherein the carbohydrate binding domain is fused to the N-terminus or the C-terminus of the variant.
[40] The variant of paragraph 38 or 39, which comprises or consists of SEQ ID NO: 78 or the mature polypeptide thereof.
[41] The variant of any of paragraphs 1-40, which has an increased specific performance relative to the parent.
[42] The variant of any of paragraphs 1-41, which is isolated.
[43] An isolated polynucleotide encoding the variant of any of paragraphs 1-42.
[44] A nucleic acid construct or expression vector comprising the polynucleotide of paragraph 43.
[45] A host cell comprising the polynucleotide of paragraph 43.
[46] A method of producing a cellobiohydrolase variant, comprising: cultivating the host cell of paragraph 45 under conditions suitable for expression of the variant.
[47] The method of paragraph 46, further comprising recovering the variant.
[48] A transgenic plant, plant part or plant cell transformed with the polynucleotide of paragraph 43.
[49] A method of producing the variant of any of paragraphs 1-42, comprising: cultivating a transgenic plant or a plant cell comprising a polynucleotide encoding the variant under conditions conducive for production of the variant.
[50] The method of paragraph 49, further comprising recovering the variant
[51] A method for obtaining a cellobiohydrolase variant, comprising introducing into a parent cellobiohydrolase deletions at two or more consecutive positions of the B2-loop, wherein the variant has cellobiohydrolase activity.
[52] A method for obtaining a cellobiohydrolase variant, comprising introducing into a parent cellobiohydrolase a deletion at one or more positions corresponding to positions 195, 196, 197, and 198, of SEQ ID NO: 2, wherein the variant has cellobiohydrolase activity.
[53] The method of paragraph 51 or 52, further comprising recovering the variant.
[54] A composition comprising the variant of any of paragraphs 1-42.
[55] A whole broth formulation or cell culture composition comprising the variant of any of paragraphs 1-42.
[56] A process for degrading a cellulosic material, comprising: treating the cellulosic material with an enzyme composition in the presence of the variant of any of paragraphs 1-42.
[57] The process of paragraph 56, wherein the cellulosic material is pretreated.
[58] The process of paragraph 56 or 57, wherein the enzyme composition comprises one or more enzymes selected from the group consisting of a cellulase, a GH61 polypeptide having cellulolytic enhancing activity, a hemicellulase, a catalase, an esterase, an expansin, a laccase, a ligninolytic enzyme, a pectinase, a peroxidase, a protease, and a swollenin.
[59] The process of paragraph 58, wherein the cellulase is one or more enzymes selected from the group consisting of an endoglucanase, a cellobiohydrolase, and a beta-glucosidase.
[60] The process of paragraph 58, wherein the hemicellulase is one or more enzymes selected from the group consisting of a xylanase, an acetylxylan esterase, a feruloyl esterase, an arabinofuranosidase, a xylosidase, and a glucuronidase.
[61] The process of any of paragraphs 56-60, further comprising recovering the degraded cellulosic material.
[62] The process of paragraph 61, wherein the degraded cellulosic material is a sugar.
[63] The process of paragraph 62, wherein the sugar is selected from the group consisting of glucose, xylose, mannose, galactose, and arabinose.
[64] A process for producing a fermentation product, comprising: (a) saccharifying a cellulosic material with an enzyme composition in the presence of the variant of any of paragraphs 1-42; (b) fermenting the saccharified cellulosic material with one or more fermenting microorganisms to produce the fermentation product; and (c) recovering the fermentation product from the fermentation.
[65] The process of paragraph 64, wherein the cellulosic material is pretreated.
[66] The process of paragraph 64 or 65, wherein the enzyme composition comprises the enzyme composition comprises one or more enzymes selected from the group consisting of a cellulase, a GH61 polypeptide having cellulolytic enhancing activity, a hemicellulase, a catalase, an esterase, an expansin, a laccase, a ligninolytic enzyme, a pectinase, a peroxidase, a protease, and a swollenin.
[67] The process of paragraph 66, wherein the cellulase is one or more enzymes selected from the group consisting of an endoglucanase, a cellobiohydrolase, and a beta-glucosidase.
[68] The process of paragraph 66, wherein the hemicellulase is one or more enzymes selected from the group consisting of a xylanase, an acetylxylan esterase, a feruloyl esterase, an arabinofuranosidase, a xylosidase, and a glucuronidase.
[69] The process of any of paragraphs 64-68, wherein steps (a) and (b) are performed simultaneously in a simultaneous saccharification and fermentation.
[70] The process of any of paragraphs 64-69, wherein the fermentation product is an alcohol, an alkane, a cycloalkane, an alkene, an amino acid, a gas, isoprene, a ketone, an organic acid, or polyketide.
[71] A process of fermenting a cellulosic material, comprising: fermenting the cellulosic material with one or more fermenting microorganisms, wherein the cellulosic material is saccharified with an enzyme composition in the presence of the variant of any of paragraphs 1-42.
[72] The process of paragraph 71, wherein the fermenting of the cellulosic material produces a fermentation product.
[73] The process of paragraph 72, further comprising recovering the fermentation product from the fermentation.
[74] The process of paragraph 72 or 73, wherein the fermentation product is an alcohol, an alkane, a cycloalkane, an alkene, an amino acid, a gas, isoprene, a ketone, an organic acid, or polyketide.
[75] The process of any of paragraphs 71-74, wherein the cellulosic material is pretreated before saccharification.
[76] The process of any of paragraphs 71-75, wherein the enzyme composition comprises one or more enzymes selected from the group consisting of a cellulase, a GH61 polypeptide having cellulolytic enhancing activity, a hemicellulase, a catalase, an esterase, an expansin, a laccase, a ligninolytic enzyme, a pectinase, a peroxidase, a protease, and a swollenin.
[77] The process of paragraph 76, wherein the cellulase is one or more enzymes selected from the group consisting of an endoglucanase, a cellobiohydrolase, and a beta-glucosidase.
[78] The process of paragraph 77, wherein the hemicellulase is one or more enzymes selected from the group consisting of a xylanase, an acetylxylan esterase, a feruloyl esterase, an arabinofuranosidase, a xylosidase, and a glucuronidase.
The present invention is further described by the following examples that should not be construed as limiting the scope of the invention.
Examples
Strains
Aspergillus oryzae strain MT3568 was used as a host for expression of the Trichoderma reesei gene encoding cellobiohydrolase I and a variant thereof. A. oryzae MT3568 is an amdS (acetamidase) disrupted gene derivative of Aspergillus oryzae JaL355 (WO 2002/40694) in which pyrG auxotrophy was restored by disrupting the A. oryzae acetamidase (amdS) gene.
Media and Solutions
COVE sucrose plates or slants were composed of 342 g of sucrose, 20 g of agar powder, 20 ml of COVE salt solution, and deionized water to 1 liter. The medium was sterilized by autoclaving at 15 psi for 15 minutes (Bacteriological Analytical Manual, 8th Edition, Revision A, 1998). The medium was cooled to 60° C. and then acetamide to 10 mM, CsCl to 15 mM, and TRITON® X-100 (50 μl/500 ml) were added.
COVE salt solution was composed of 26 g of MgSO 4 .7H 2 O, 26 g of KCl, 26 g of KH 2 PO 4 , 50 ml of COVE trace metals solution, and deionized water to 1 liter.
COVE trace metals solution was composed of 0.04 g of Na 2 B 4 O 7 .10H 2 O, 0.4 g of CuSO 4 .5H 2 O, 1.2 g of FeSO 4 .7H 2 O, 0.7 g of MnSO 4 .H 2 O, 0.8 g of Na 2 MoO 4 .2H 2 O, 10 g of ZnSO 4 .7H 2 O, and deionized water to 1 liter.
DAP-4C medium was composed of 20 g of dextrose, 10 g of maltose, 11 g of MgSO 4 .7H 2 O, 1 g of KH 2 PO 4 , 2 g of citric acid, 5.2 g of K 3 PO 4 .H 2 O, 0.5 g of yeast extract (Difco), 1 ml of antifoam, 0.5 ml of KU6 trace metals solution, 2.5 g of CaCO 3 , and deionized water to 1 liter. The medium was sterilized by autoclaving at 15 psi for 15 minutes (Bacteriological Analytical Manual, 8th Edition, Revision A, 1998). Before use, 3.5 ml of sterile 50% (NH 4 ) 2 HPO 4 and 5 ml of sterile 20% lactic acid were added per 150 ml.
G2-Gly medium was composed of 18 g of yeast extract, 24 g of glycerol (86-88%), 1 ml of antifoam, and deionized water to 1 liter.
KU6 trace metals solution was composed of 0.13 g of NiCl 2 , 2.5 g of CuSO 4 .5H 2 O, 13.9 g of FeSO 4 .7H 2 O, 8.45 g of MnSO 4 .H 2 O, 6.8 g of ZnCl 2 , 3 g of citric acid, and deionized water to 1 liter.
LB medium was composed of 10 g of Bacto-Tryptone, 5 g of yeast extract, 10 g of sodium chloride, and deionized water to 1 liter.
LB plates were composed of 10 g of Bacto-Tryptone, 5 g of yeast extract, 10 g of sodium chloride, 15 g of Bacto-agar, and deionized water to 1 liter.
PDA plates were composed of potato infusion made by boiling 300 g of sliced (washed but unpeeled) potatoes in water for 30 minutes and then decanting or straining the broth through cheesecloth. Distilled water was then added until the total volume of the suspension was 1 liter. Then 20 g of dextrose and 20 g of agar powder were added. The medium was sterilized by autoclaving at 15 psi for 15 minutes (Bacteriological Analytical Manual, 8th Edition, Revision A, 1998).
TAE buffer was composed of 40 mM Tris base, 20 mM sodium acetate, and 1 mM disodium EDTA.
YP+2% glucose medium was composed of 1% yeast extract, 2% peptone, and 2% glucose in deionized water.
YP+2% maltose medium was composed of 10 g of yeast extract, 20 g of peptone, 20 g of maltose, and deionized water to 1 liter.
Example 1: Source of DNA Sequence Information for Trichoderma reesei Cellobiohydrolase I
The genomic DNA sequence and deduced amino acid sequence of the Trichoderma reesei GH7 cellobiohydrolase I gene is shown in SEQ ID NO: 1 and SEQ ID NO: 2, respectively. Genomic sequence information was generated by the U.S. Department of Energy Joint Genome Institute (JGI) and published by Martinez et al., 2008 , Nature Biotechnology 26 (5): 553-560. The amino acid sequence of the full-length cellobiohydrolase I is publicly available from the National Center for Biotechnology Information (NCBI) and annotated as GenBank: EGR44817.1 (SEQ ID NO: 2). The cDNA sequence and deduced amino acid sequence of the Trichoderma reesei cellobiohydrolase I gene is shown in SEQ ID NO: 3 and SEQ ID NO: 2, respectively.
Based on the publicly available amino acid sequence, a codon-optimized synthetic gene encoding the full-length cellobiohydrolase I was generated for Aspergillus oryzae expression based on the algorithm developed by Gustafsson et al., 2004 , Trends in Biotechnology 22 (7): 346-353. The codon-optimized coding sequence (SEQ ID NO: 4) was synthesized by the GENEART® Gene Synthesis service (Life Technologies Corp., San Diego. Calif., USA) with a 5′ Bam HI restriction site, a 3′ Hind III restriction site, and a Kozac consensus sequence (CACC) situated between the start codon and the Bam HI restriction site.
Example 2: Site-Directed Mutagenesis of the Trichoderma reesei Cellobiohydrolase I
The codon-optimized synthetic gene encoding the T. reesei cellobiohydrolase I was provided in a non-specified kanamycin-resistant E. coli cloning vector. To generate the T. reesei cellobiohydrolase I M6 variant (SEQ ID NO: 5 for the mutant DNA sequence and SEQ ID NO: 6 for the variant), an AAC codon (N197) was replaced with a GCC codon (197A) and an AAC codon (N200) was replaced with a GCC codon (200A). Two synthetic primers for site-directed mutagenesis were designed as shown below using the QUIKCHANGE® Primer Design (Agilent Technologies, Inc., Wilmington, Del., USA) online tool to introduce the site-directed mutations changing an AAC codon (N197) to a GCC codon (197A) and an AAC codon (N200) to a GCC codon (200A).
Site-directed mutagenesis of the synthetic gene encoding the wild-type T. reesei cellobiohydrolase was facilitated by two PCR amplifications of the kanamycin-resistant E. coli cloning vector provided by GENEART® Gene Synthesis using the primers and procedure described below:
Primer F-N197A:
(SEQ ID NO: 23)
5′-GGGAACCCTCGTCGGCCAACGCCAACACCG-3′
Primer R-N197A:
(SEQ ID NO: 24)
5′-CGGTGTTGGCGTTGGCCGACGAGGGTTCCC-3′
Primer F-N200A:
(SEQ ID NO: 25)
5′-TCGTCGGCCAACGCCGCCACCGGCATTGGAGG-3′
Primer R-N200A:
(SEQ ID NO: 26)
5′-CCTCCAATGCCGGTGGCGGCGTTGGCCGACGA-3′
The two mutations were introduced consecutively by PCR using a PHUSION® High-Fidelity PCR Kit (Finnzymes Oy, Espoo, Finland). The PCR solution was composed of 10 μl of 5× HF buffer (Finnzymes Oy, Espoo, Finland), 1 μl of dNTPs (10 mM), 0.5 μl of PHUSION® DNA polymerase (0.2 units/μl) (Finnzymes Oy, Espoo, Finland), 2.5 μl of primer F-N197A (10 μM), 2.5 μl of primer R-N197A (10 μM), 1 μl of template DNA (GENEART® vector, 10 ng/μl), and 32.5 μl of deionized water in a total volume of 50 μl. The PCR was performed using a PTC-200 DNA Engine (MJ Research Inc., Waltham, Mass., USA) programmed for 1 cycle at 98° C. for 30 seconds; and 16 cycles each at 98° C. for 30 seconds, 55° C. for 1 minute, and 72° C. for 4 minutes. The PCR solution was then held at 15° C. until removed from the PCR machine.
Following PCR, 10 units of Dpn I were added directly to the PCR solution and incubated at 37° C. for 1 hour. Then 1 μl of the Dpn I treated PCR solution was transformed into ONE SHOT® TOP10F′ Chemically Competent E. coli cells (Invitrogen, Carlsbad, Calif., USA) according to the manufacturer's protocol and spread onto LB plates supplemented with 0.05 mg of kanamycin per ml. After incubation at 37° C. overnight, transformants were observed growing under selection on the LB kanamycin plates. Two transformants were cultivated in LB medium supplemented with 0.05 mg of kanamycin per ml and plasmids were isolated using a QIAPREP® Spin Miniprep Kit (QIAGEN Inc., Valencia, Calif., USA).
The isolated plasmids were sequenced using an Applied Biosystems 3730xl DNA Analyzer (Applied Biosystems, Foster City, Calif., USA) with vector primers and a T. reesei cellobiohydrolase I gene specific primer (R-Central), shown below, in order to determine a representative plasmid that was free of PCR errors and contained the AAC to GCC mutation.
Primer F-vector:
(SEQ ID NO: 27)
5′-CGTTGTAAAACGACGGCC-3′
Primer R-vector:
(SEQ ID NO: 28)
5′-TGTTAATGCAGCTGGCAC-3′
Primer R-Central:
(SEQ ID NO: 29)
5′-CTTGTCGGAGAACGACGA-3′
One plasmid clone free of PCR errors and containing the AAC (N197) to GCC (197A) mutation was chosen and designated plasmid pN197A.
A second round of PCR was performed to introduce the N200A mutation by PCR using a PHUSION® High-Fidelity PCR Kit. The PCR solution was composed of 10 μl of 5× HF buffer, 1 μl of dNTPs (10 mM), 0.5 μl of PHUSION® DNA polymerase (0.2 units/μl), 2.5 μl of primer F-N200A (10 μM), 2.5 μl of primer R-N200A (10 μM), 1 μl of template DNA (pN197A, 10 ng/μl), and 32.5 μl of deionized water in a total volume of 50 μl. The PCR was performed using a PTC-200 DNA Engine programmed for 1 cycle at 98° C. for 30 seconds; and 16 cycles each at 98° C. for 30 seconds, 55° C. for 1 minute, and 72° C. for 4 minutes. The PCR solution was then held at 15° C. until removed from the PCR machine.
Following PCR, 10 units of Dpn I were added directly to the PCR solution and incubated at 37° C. for 1 hour. Then 1 μl of the Dpn I treated PCR solution was transformed into ONE SHOT® TOP10F′ Chemically Competent E. coli cells according to the manufacturer's protocol and spread onto LB plates supplemented with 0.05 mg of kanamycin per ml. After incubation at 37° C. overnight, transformants were observed growing under selection on the LB kanamycin plates. Two transformants were cultivated in LB medium supplemented with 0.05 mg of kanamycin per ml and plasmids were isolated using a QIAPREP® Spin Miniprep Kit.
The isolated plasmids were sequenced using an Applied Biosystems 3730xl DNA Analyzer with primers F-vector, R-vector, and R-Central shown above in order to determine a representative plasmid that was free of PCR errors and contained the AAC to GCC mutation.
One plasmid clone free of PCR errors and containing the AAC (N197) to GCC (197A) and ACC (N200) to GCC (200A) mutations was chosen and designated plasmid pM6. The variant is designated herein as “M6 variant”.
Example 3: Construction of an Aspergillus oryzae Expression Vector Containing a Trichoderma reesei cDNA Sequence Encoding Cellobiohydrolase I
The kanamycin-resistant E. coli cloning vector provided by GENEART® Gene Synthesis encoding the T. reesei cellobiohydrolase I (SEQ ID NO: 4) was digested with Fast Digest Bam HI and Hind III (Fermentas Inc., Glen Burnie, Md., USA) according to manufacturer's instructions. The reaction products were isolated by 1.0% agarose gel electrophoresis using TAE buffer where a 1552 bp product band was excised from the gel and purified using an ILLUSTRA™ GFX™ DNA Purification Kit (GE Healthcare Life Sciences, Brondby, Denmark).
The 1552 bp fragment was then cloned into pDau109 (WO 2005/042735) digested with Bam HI and Hind III using T4 DNA ligase (New England Biolabs, Ipswich, Mass., USA). The Bam HI-Hind III digested pDau109 and the Bam HI/Hind III fragment containing the T. reesei cellobiohydrolase I coding sequence were mixed in a molar ratio of 1:3 (i.e., mass ratio approximately 2.5:1 or 20 ng:50 ng) and ligated with 50 units of T4 DNA ligase in 1× T4 DNA ligase buffer (New England Biolabs, Ipswich, Mass., USA) with 1 mM ATP at 16° C. over-night in accordance with the manufacturer's instructions. Cloning of the T. reesei cellobiohydrolase I gene into the Bam HI-Hind III digested pDau109 resulted in transcription of the T. reesei cellobiohydrolase I gene under the control of a NA2-tpi double promoter. The NA2-tpi promoter is a modified promoter from the gene encoding the Aspergillus niger neutral alpha-amylase in which the untranslated leader has been replaced by an untranslated leader from the gene encoding the Aspergillus nidulans triose phosphate isomerase.
The ligation mixture was transformed into ONE SHOT® TOP10F′ Chemically Competent E. coli cells according to the manufacturer's protocol and spread onto LB plates supplemented with 0.1 mg of ampicillin per ml. After incubation at 37° C. overnight, colonies were observed growing under selection on the LB ampicillin plates
Insertion of the T. reesei cellobiohydrolase I gene into pDau109 was verified by PCR on colonies as described below using the following primers.
Primer F-pDau109
(SEQ ID NO: 30)
5′-CCCTTGTCGATGCGATGTATC-3′
Primer R-pDau109
(SEQ ID NO: 31)
5′-ATCCTCAATTCCGTCGGTCGA-3′
A 1.1× REDDYMIX® Master Mix (Thermo Fisher Scientific, Roskilde, Denmark) was used for the PCR. The PCR solution was composed of 10 μl of 1.1× REDDYMIX® Master Mix, 0.5 μl of primer F-pDau109 (10 μM), and 0.5 μl of primer R-pDau109 (10 μM). A toothpick was used to transfer a small amount of cells to the PCR solution. The PCR was performed using a PTC-200 DNA Engine programmed for 1 cycle at 94° C. for 3 minutes; 30 cycles each at 94° C. for 30 seconds, 50° C. for 1 minute, and 72° C. for 2 minutes; and 1 cycle at 72° C. for 1 minute. The PCR solution was then held at 15° C. until removed from the PCR machine.
The PCR products were analyzed by 1.0% agarose gel electrophoresis using TAE buffer where a 1860 bp PCR product band was observed confirming insertion of the T. reesei cellobiohydrolase I coding sequence into pDau109.
An E. coli transformant containing the T. reesei cellobiohydrolase I plasmid construct was cultivated in LB medium supplemented with 0.1 mg of ampicillin per ml and plasmid DNA was isolated using a QIAPREP® Spin Miniprep Kit. The plasmid was designated pKHJN0036.
Example 4: Construction of an Aspergillus oryzae Expression Vector Containing Trichoderma reesei cDNA Sequence Encoding the Cellobiohydrolase I M6 Variant
Plasmid pM6 encoding the T. reesei cellobiohydrolase I M6 variant was digested with Fast Digest Bam HI and Hind III according to manufacturer's instructions. The reaction products were isolated by 1.0% agarose gel electrophoresis using TAE buffer where a 1552 bp product band was excised from the gel and purified using an ILLUSTRA™ GFX™ DNA Purification Kit.
The 1552 bp fragment was then cloned into pDau109 digested with Bam HI and Hind III using T4 DNA ligase. The Bam HI-Hind III digested pDau109 and the Bam HI/Hind III fragment containing the T. reesei cellobiohydrolase I M6 variant coding sequence were mixed in a molar ratio of 1:3 (i.e., mass ratio approximately 2.5:1 or 20 ng:50 ng) and ligated with 50 units of T4 DNA ligase in 1× T4 DNA ligase buffer with 1 mM ATP at 16° C. overnight. Cloning of the T. reesei cellobiohydrolase I M6 variant gene into the Bam HI-Hind III digested pDau109 resulted in transcription of the T. reesei cellobiohydrolase I M6 variant gene under the control of a NA2-tpi double promoter described above.
The ligation mixture was transformed into ONE SHOT® TOP10F′ Chemically Competent E. coli cells according to the manufacturer's protocol and spread onto LB plates supplemented with 0.1 mg of ampicillin per ml. After incubation at 37° C. overnight, colonies were observed growing under selection on the LB ampicillin plates
Insertion of the T. reesei cellobiohydrolase I M6 variant gene into pDau109 was verified by PCR on colonies as described below using primers F-pDau109 and R-pDau109 (Example 3) shown below.
Primer F-pDau109
(SEQ ID NO: 30)
5′-CCCTTGTCGATGCGATGTATC-3′
Primer R-pDau109
(SEQ ID NO: 31)
5′-ATCCTCAATTCCGTCGGTCGA-3′
A 1.1× REDDYMIX® Master Mix was used for the PCR. The PCR solution was composed of 10 μl of 1.1× REDDYMIX® Master Mix, 0.5 μl of primer F-pDau109 (10 μM), and 0.5 μl of primer R-pDau109 (10 μM). A toothpick was used to transfer a small amount of cells to the PCR solution. The PCR was performed using a PTC-200 DNA Engine programmed for 1 cycle at 94° C. for 3 minutes; 30 cycles each at 94° C. for 30 seconds, 50° C. for 1 minute, and 72° C. for 2 minutes; and 1 cycle at 72° C. for 1 minute. The PCR solution was then held at 15° C. until removed from the PCR machine.
The PCR reaction products were analyzed by 1.0% agarose gel electrophoresis using TAE buffer where a 1860 bp PCR product band was observed confirming insertion of the T. reesei cellobiohydrolase I M6 variant coding sequence into pDau109.
An E. coli transformant containing the T. reesei cellobiohydrolase I M6 variant plasmid construct was cultivated in LB medium supplemented with 0.1 mg of ampicillin per ml and plasmid was isolated using a QIAPREP® Spin Miniprep Kit. The plasmid was designated pKHJN0059.
Example 5: Expression of the Wild-Type Trichoderma reesei Cellobiohydrolase I
The expression plasmid pKHJN0036 was transformed into Aspergillus oryzae MT3568 protoplasts according to Christensen et al., 1988 , Biotechnology 6, 1419-1422 and WO 2004/032648. A. oryzae MT3568 protoplasts were prepared according to the method of EP 0238023 B1, pages 14-15.
Transformants were purified on COVE sucrose plates through single conidia prior to sporulating them on PDA plates. Spores of the transformants were inoculated into 96 deep well plates containing 0.75 ml of YP+2% glucose medium and incubated stationary at 30° C. for 4 days. Production of the T. reesei cellobiohydrolase I by the transformants was analyzed from culture supernatants of the 96 deep well cultivations. Expression was verified by SDS-PAGE analysis using an E-Page 8% SDS-PAGE 48 well gel (Invitrogen, Carlsbad, Calif., USA) and Coomassie blue staining. Based on the level of expression by SDS-PAGE, one transformant was selected and designated Aspergillus oryzae CBH I.
For larger scale production, A. oryzae CBH I spores were spread onto COVE sucrose slants and incubated for five days at 37° C. The confluent spore slants were washed twice with 5 ml of 0.01% TWEEN® 20 to maximize the number of spores collected. The spore suspensions were then used to inoculate seven 500 ml flasks containing 150 ml of DAP-4C medium. The cultures were incubated at 30° C. with constant shaking at 100 rpm. At day four post-inoculation, the culture broths were collected by filtration through a bottle top MF75 Supor MachV 0.2 μm PES filter (Thermo Fisher Scientific, Roskilde, Denmark). Expression was verified by SDS-PAGE analysis using an E-Page 8% SDS-PAGE 48 well gel and Coomassie staining. The culture broths from A. oryzae CBH I produced a band at approximately 80 kDa for the T. reesei cellobiohydrolase I.
Example 6: Expression of the Trichoderma reesei Cellobiohydrolase I M6 Variant
The expression plasmid pKHJN0059 was transformed into Aspergillus oryzae MT 3568 protoplasts according to Christensen et al., 1988, supra and WO 2004/032648. A. oryzae MT3568 protoplasts were prepared according to the method of European Patent, EP0238023, pages 14-15.
Transformants were purified on COVE sucrose plates through single conidia prior to sporulating them on PDA plates. Spores of the transformants were inoculated into 96 deep well plates containing 0.75 ml of YP+2% glucose medium and incubated stationary at 30° C. for 4 days. Production of the T. reesei cellobiohydrolase I M6 variant by the transformants was analyzed from culture supernatants of the 96 deep well cultivations. Expression was verified by SDS-PAGE analysis using an E-Page 8% SDS-PAGE 48 well gel and Coomassie staining. Based on the level of expression by SDS-PAGE, one transformant was selected for further work and designated Aspergillus oryzae M6.
For larger scale production, A. oryzae M6 spores were spread onto COVE sucrose slants and incubated for five days at 37° C. The confluent spore slants were washed twice with 5 ml of 0.01% TWEEN® 20 to maximize the number of spores collected. The spore suspensions were then used to inoculate seven 500 ml flasks containing 150 ml of DAP-4C medium. The cultures were incubated at 30° C. with constant shaking at 100 rpm. At day four post-inoculation, the culture broths were collected by filtration through a bottle top MF75 Supor MachV 0.2 μm PES filter. Expression was verified by SDS-PAGE analysis using an E-Page 8% SDS-PAGE 48 well gel and Coomassie staining. The culture broths from A. oryzae M6 produced a band at approximately 80 kDa for the T. reesei cellobiohydrolase I M6 variant.
Example 7: Purification of the Trichoderma reesei Wild-Type Cellobiohydrolase I and Cellobiohydrolase I M6 Variant
The filtered broths of A. oryzae CBH I (Example 5) and A. oryzae M6 (Example 6) were adjusted to pH 7.0 and filtered using a 0.22 μm PES filter (Nalge Nunc International Corp., Rochester, N.Y., USA). Then ammonium sulphate was added to each filtrate to a concentration of 1.8 M.
Each filtrate was purified according to the following procedure. The filtrate was loaded onto a Phenyl SEPHAROSE® 6 Fast Flow column (high sub) (GE Healthcare, United Kingdom) equilibrated with 1.8 M ammonium sulphate, 25 mM HEPES pH 7.0. After a wash with 0.54 M ammonium sulphate, the bound proteins were batch eluted with 25 mM HEPES pH 7.0. Fractions were collected and analyzed by SDS-PAGE using 12-well NUPAGE® 4-12% Bis-Tris gel (GE Healthcare, Piscataway, N.J., USA). The fractions were pooled based on SDS-PAGE as above and applied to a SEPHADEX™ G-25 (medium) column (GE Healthcare, United Kingdom) equilibrated with 25 mM MES pH 6.0. Fractions were collected, analyzed by SDS-PAGE as above, and pooled. The pooled fractions were applied to a 6 ml RESOURCE™ 15Q column (GE Healthcare, United Kingdom) equilibrated with 25 mM MES pH 6.0 and bound proteins were eluted with a linear 0-300 mM sodium chloride gradient (12 column volumes) for the wild-type cellobiohydrolase or a linear 0-350 mM sodium chloride gradient (14 column volumes) for the variant. Fractions were collected and analyzed by SDS-PAGE, A 280 , and activity measurements using 4-nitrophenyl-beta-D-glucopyranoside (Sigma Chemical Co., St. Louis, Mo., USA) and 4-nitrophenyl-beta-D-lactopyranoside (Sigma Chemical Co., St. Louis, Mo., USA) as substrates. The assays were performed in 96-well Nunc microtiter plates (Thermo Scientific, Sunnyvale, Calif., USA). The assay buffer was 50 mM Britton-Robinson buffer (50 mM H 3 PO 4 , 50 mM CH 3 COOH, 50 mM H 3 BO 3 ) with 50 mM KCl, 1 mM CaCl 2 , 0.01% TRITON® X-100, pH adjusted to 6.0 with NaOH. A 20 μl sample of protein solution was pipetted into each well and 120 μl of 1 mM substrate in the assay buffer were added. The substrate 4-nitrophenyl-beta-D-glucopyranoside was used to determine beta-glucosidase activity and 4-nitrophenyl-beta-D-lactopyranoside for cellobiohydrolase I and cellobiohydrolase variant activity. A standard curve was made by replacing the protein solution with 20 μl of 4-nitrophenolate standard (0, 0.05, 0.075, 0.1, 0.2, 0.3, 0.4, 0.5 mM). If necessary, samples were diluted in the assay buffer to yield absorptions within the range of the standard curve. The plate was sealed and incubated in a thermomixer at 37° C. for 15 minutes with 750 rpm shaking. Immediately after incubation the reaction was stopped by adding 100 μl of 0.5 M glycine-2 mM EDTA pH 10 and the absorption was measured at 405 nm. The absorption of a “blank”, in which the protein was added after the stop solution, was recorded for each sample and subtracted from the result to obtain the absorption of released 4-nitrophenolate.
Based on SDS-PAGE, A 280 , and the activity measurements, the fractions were pooled to the final product.
The T. reesei wild-type cellobiohydrolase I and cellobiohydrolase I M6 variant were purified to a concentration of 57 μM and 38 μM, respectively, as determined by A 280 using the calculated molar extinction coefficient 84810 M −1 ·cm −1 and 84810 M −1 ·cm −1 , respectively.
Example 8: Activity Measurement on Microcrystalline Cellulose of the Trichoderma Reesei Cellobiohydrolase M6 Variant
The activity of the purified cellobiohydrolase I M6 variant (Example 7) was compared to the purified T. reesei wild-type cellobiohydrolase I (Example 7) using microcrystalline cellulose (AVICEL® PH101; Sigma-Aldrich, St. Louis, Mo., USA) as a substrate. The microcrystalline cellulose was suspended at 60 g per liter of 2 mM CaCl 2 -50 mM sodium acetate pH 5 as assay buffer.
Activity of the T. reesei wild-type cellobiohydrolase I and cellobiohydrolase I M6 variant was measured in a water-jacketed glass cell connected to a Julabo F12 water bath (Buch & Holm A/S, Herlev, Denmark). Each reaction chamber was filled with 5 ml of the microcrystalline cellulose suspension and magnetically stirred at 600 rpm. The enzyme was injected into the cell using 250 μl glass syringes (Hamilton Co., Boston, Mass., USA) with a Fusion 100 syringe pump (Chemyx Inc., Stafford, Tex., USA) to a final concentration of 100 nM (5 μg/ml) with an injection time of 1 second (wild-type: 8.8 μl, 528 μl/minute; M6 variant: 13.16 μl, 789 μl/minute). The reactions were allowed to proceed for 5 hours at 25° C. before being quenched with 80 μl of 1 M NaOH.
From each reaction 2 samples of 2 ml were removed and filtered with a 0.2 μM hydrophilic MINISART® NML syringe filter (Sartorius Stedim Biotech S.A., Goettingen, Germany). The filtrates were diluted 1:10 with milliQ water (control was measured undiluted) and the glucose, cellobiose, and cellotriose contents were analyzed using a Dionex ICS-5000 DC High-Performance Liquid Chromatography (HPLC) System (Thermo Scientific, Sunnyvale, Calif., USA) equipped with a 4 mm×25 cm CARBOPAC™ PA10 column (Thermo Scientific, Sunnyvale, Calif., USA), a Dionex GP40 gradient pump (Thermo Scientific, Sunnyvale, Calif., USA), and a Dionex ED40 electrochemical detector (Thermo Scientific, Sunnyvale, Calif., USA) with a gold working electrode (standard carbohydrate settings). Oligosaccharides were separated on the CARBOPAC™ PA10 column using the following gradient program at a flow rate of 1 ml per minute: 0-4 minutes isocratic elution with 50 mM sodium hydroxide; 4-28 minutes linear gradient to 100 mM sodium acetate in 90 mM sodium hydroxide; 28-29 minutes linear gradient to 450 mM sodium acetate in 200 mM sodium hydroxide; 29-30 minutes linear gradient to 100 mM sodium hydroxide; 30-31 minutes linear gradient to 50 mM sodium hydroxide; and 31-35 minutes reequilibration under the initial conditions. Combined external standards were ([glucose]/[cellobiose]/[cellotriose]): 1 μM/2 μM/0.5 μM, 2 μM/4 μM/1 μM, 3 μM/6 μM/1.5 μM, 4 μM/8 μM/2 μM, and 5 μM/10 μM/2.5 μM. Chromatogram peak integration, standard curve, and concentration determination were performed using a CHROMELEON® 7 Chromatography Data System (Thermo Fisher Scientific, Roskilde, Denmark).
The results as shown in FIG. 1 and Table 1 demonstrated that the cellobiohydrolase I M6 variant had an approximately 65% increase in activity toward microcrystalline cellulose compared to the wild-type cellobiohydrolase.
TABLE 1
Saccharide production from microcrystalline cellulose by the
T. reesei wild-type cellobiohydrolase I and the cellobiohydrolase
I M6 variant thereof after 5 hours at pH 5 and 25° C.
[glucose] (μM)
[cellobiose] (μM)
[cellotriose] (μM)
Control
15.9
1.6
2.5
Wild-type
22.9 ± 0.3
121.4 ± 4.3
5.4 ± 4 × 10 −3
M6 Variant
29.1 ± 10 −3
201.7 ± 0.5
8.1 ± 0.04
Example 9: Pretreated Corn Stover Hydrolysis Assay
Corn stover was pretreated at the U.S. Department of Energy National Renewable Energy Laboratory (NREL) using 1.4 wt % sulfuric acid at 165° C. and 107 psi for 8 minutes. The water-insoluble solids in the pretreated corn stover (PCS) contained 56.5% cellulose, 4.6% hemicellulose, and 28.4% lignin. Cellulose and hemicellulose were determined by a two-stage sulfuric acid hydrolysis with subsequent analysis of sugars by high performance liquid chromatography using NREL Standard Analytical Procedure #002. Lignin was determined gravimetrically after hydrolyzing the cellulose and hemicellulose fractions with sulfuric acid using NREL Standard Analytical Procedure #003.
Unmilled, unwashed PCS (whole slurry PCS) was prepared by adjusting the pH of the PCS to 5.0 by addition of 10 M NaOH with extensive mixing, and then autoclaving for 20 minutes at 120° C. The dry weight of the whole slurry PCS was 29%. Milled unwashed PCS (dry weight 32.35%) was prepared by milling whole slurry PCS in a Cosmos ICMG 40 wet multi-utility grinder (EssEmm Corporation, Tamil Nadu, India).
The hydrolysis of PCS was conducted using 2.2 ml deep-well plates (Axygen, Union City, Calif., USA) in a total reaction volume of 1.0 ml. The hydrolysis was performed with 50 mg of insoluble PCS solids per ml of 50 mM sodium acetate pH 5.0 buffer containing 1 mM manganese sulfate and various protein loadings of various enzyme compositions (expressed as mg protein per gram of cellulose). Enzyme compositions were prepared and then added simultaneously to all wells in a volume ranging from 50 μl to 200 μl, for a final volume of 1 ml in each reaction. The plate was then sealed using an ALPS-300™ plate heat sealer (Abgene, Epsom, United Kingdom), mixed thoroughly, and incubated at a specific temperature for 72 hours. All experiments reported were performed in triplicate.
Following hydrolysis, samples were filtered using a 0.45 μm MULTISCREEN® 96-well filter plate (Millipore, Bedford, Mass., USA) and filtrates analyzed for sugar content as described below. When not used immediately, filtered aliquots were frozen at −20° C. The sugar concentrations of samples diluted in 0.005 M H 2 SO 4 were measured using a 4.6×250 mm AMINEX® HPX-87H column (Bio-Rad Laboratories, Inc., Hercules, Calif., USA) by elution with 0.05% w/w benzoic acid-0.005 M H 2 SO 4 at 65° C. at a flow rate of 0.6 ml per minute, and quantitation by integration of the glucose, cellobiose, and xylose signals from refractive index detection (CHEMSTATION®, AGILENT® 1100 HPLC, Agilent Technologies, Santa Clara, Calif., USA) calibrated by pure sugar samples. The resultant glucose and cellobiose equivalents were used to calculate the percentage of cellulose conversion for each reaction.
Glucose and cellobiose were measured individually. Measured sugar concentrations were adjusted for the appropriate dilution factor. The net concentrations of enzymatically-produced sugars from unwashed PCS were determined by adjusting the measured sugar concentrations for corresponding background sugar concentrations in unwashed PCS at zero time point. All HPLC data processing was performed using MICROSOFT EXCEL™ software (Microsoft, Richland, Wash., USA).
The degree of cellulose conversion to glucose was calculated using the following equation: % cellulose conversion=[glucose concentration+(1.053× cellobiose concentration)]/[(glucose concentration+(1.053× cellobiose concentration) in a limit digest]×100. In order to calculate % cellulose conversion, a 100% conversion point was set based on a cellulase control (100 mg of T. reesei cellulase per gram cellulose. Triplicate data points were averaged and standard deviation was calculated.
Example 10: Preparation of an Enzyme Composition without Cellobiohydrolase I
The Aspergillus fumigatus GH6A cellobiohydrolase II (SEQ ID NO: 32 [DNA sequence] and SEQ ID NO: 33 [deduced amino acid sequence]) was prepared recombinantly in Aspergillus oryzae as described in WO 2011/057140. The filtered broth of the A. fumigatus cellobiohydrolase II was buffer exchanged into 50 mM sodium acetate pH 5.0 using a 400 ml SEPHADEX™ G-25 column. The fractions were pooled.
The T. reesei GH5 endoglucanase II (SEQ ID NO: 34 [DNA sequence] and SEQ ID NO: 35 [deduced amino acid sequence]) was prepared recombinantly according to WO 2011/057140 using Aspergillus oryzae as a host. The filtered broth of the T. reesei endoglucanase II was desalted and buffer-exchanged into 20 mM Tris pH 8.0 using tangential flow (10K membrane, Pall Corporation).
The Penicillium sp. ( emersonii ) GH61A polypeptide (SEQ ID NO: 36 [DNA sequence] and SEQ ID NO: 37 [deduced amino acid sequence]) was prepared recombinantly according to WO 2011/041397 using T. reesei as a host. To purify P. emersonii GH61A polypeptide, a fermentation culture medium was desalted using a tangential flow concentrator (Pall Filtron, Northborough, Mass., USA) equipped with a 5 kDa polyethersulfone membrane (Pall Filtron, Northborough, Mass., USA) into 20 mM Tris-HCl pH 8.5. The buffer-exchanged sample was loaded onto a Q SEPHAROSE® Fast Flow column (GE Healthcare, Piscataway, N.J., USA) preequilibrated with 20 mM Tris-HCl, pH 8.0, eluted with 20 mM Tris-HCl pH 8.0 and 1 M NaCl. Selected fractions were pooled, made in 0.85 M ammonium sulfate, and loaded onto a Phenyl SEPHAROSE® Fast Flow column preequilibrated with 20 mM Tris-HCl, pH 7.5 and 0.85 M ammonium sulfate, eluted with 20 mM Tris-HCl, pH 7.5. The fractions were pooled and desalted using a tangential flow concentrator (Pall Filtron, Northborough, Mass., USA) equipped with a 5 kDa polyethersulfone membrane into 50 mM sodium acetate pH 5.0.
The Aspergillus fumigatus GH10 xylanase (xyn3) (SEQ ID NO: 38 [DNA sequence] and SEQ ID NO: 39 [deduced amino acid sequence]) was prepared recombinantly according to WO 2006/078256 using Aspergillus oryzae BECh2 (WO 2000/39322) as a host. The filtered broth of the A. fumigatus xylanase was desalted and buffer-exchanged into 50 mM sodium acetate pH 5.0 using a HIPREP® 26/10 Desalting Column (GE Healthcare, Piscataway, N.J., USA).
The Aspergillus fumigatus Cel3A beta-glucosidase 4M mutant (SEQ ID NO: 40 [DNA sequence] and SEQ ID NO: 41 [deduced amino acid sequence]) was recombinantly prepared according to WO 2012/044915. The filtered broth of Aspergillus fumigatus Cel3A beta-glucosidase 4M was concentrated and buffer exchanged using a tangential flow concentrator (Pall Filtron, Northborough, Mass., USA) equipped with a 10 kDa polyethersulfone membrane (Pall Filtron, Northborough, Mass., USA) with 50 mM sodium acetate pH 5.0 containing 100 mM sodium chloride.
The Talaromyces emersonii CBS 393.64 beta-xylosidase (SEQ ID NO: 42 [DNA sequence] and SEQ ID NO: 43 [deduced amino acid sequence]) was prepared recombinantly according to Rasmussen et al., 2006 , Biotechnology and Bioengineering 94: 869-876 using Aspergillus oryzae JaL355 as a host (WO 2003/070956). The filtered broth was concentrated and desalted with 50 mM sodium acetate pH 5.0 using a tangential flow concentrator equipped with a 10 kDa polyethersulfone membrane.
The protein concentration for each of the monocomponents described above was determined using a Microplate BCA™ Protein Assay Kit (Thermo Fischer Scientific, Waltham, Mass., USA) in which bovine serum albumin was used as a protein standard. An enzyme composition was prepared composed of each monocomponent as follows: 39.7% Aspergillus fumigatus Cel6A cellobiohydrolase II, 15.9% T. reesei GH5 endoglucanase II, 23.8% Penicillium sp. ( emersonii ) GH61A polypeptide, 7.9% Aspergillus fumigatus GH10 xylanase, 7.9% Aspergillus fumigatus beta-glucosidase, and 4.8% Talaromyces emersonii beta-xylosidase. The enzyme composition is designated herein as “cellulolytic enzyme composition without cellobiohydrolase I”.
Example 11: Comparison of the Effect of the Trichoderma reesei Cellobiohydrolase I M6 Variant and Trichoderma reesei Wild-Type Cellobiohydrolase I in the Hydrolysis of Milled Unwashed PCS by a Cellulase Enzyme Composition
The T. reesei cellobiohydrolase I M6 variant and T. reesei wild-type cellobiohydrolase I were added to the cellulolytic enzyme composition without cellobiohydrolase I (Example 10) at 40° C. using milled unwashed PCS as a substrate. Each cellobiohydrolase I was added individually at 0.8633, 1.295, and 1.9425 mg enzyme protein per g cellulose to 2.205 mg enzyme protein of the cellulase enzyme composition without cellobiohydrolase I per g cellulose.
The assay was performed as described in Example 9. The 1 ml reactions with milled unwashed PCS (5% insoluble solids) were conducted for 24, 48, and 72 hours in 50 mM sodium acetate pH 5.0 buffer containing 1 mM manganese sulfate. All reactions were performed in triplicate and involved single mixing at the beginning of hydrolysis.
The results shown in FIGS. 2, 3, and 4 demonstrated that at 24, 48, and 72 hours, the cellulase enzyme composition that included the T. reesei cellobiohydrolase I M6 variant had significantly higher cellulose conversion than the cellulase enzyme composition that included T. reesei wild-type cellobiohydrolase I.
Example 12: Determination of Td by Differential Scanning Calorimetry of the Trichoderma reesei Cellobiohydrolase I M6 Variant and Trichoderma reesei Wild-Type Cellobiohydrolase I
The thermostability of the T. reesei wild-type cellobiohydrolase I and cellobiohydrolase I M6 variant was determined by Differential Scanning calorimetry (DSC) using a VP-Capillary Differential Scanning calorimeter (MicroCal Inc., Piscataway, N.J., USA). The thermal denaturation temperature, Td (° C.), was taken as the top of denaturation peak (major endothermic peak) in thermograms (Cp vs. T) obtained after heating enzyme solutions (approx. 1 mg/ml) in 50 mM sodium acetate pH 5.0 at a constant programmed heating rate of 200 K/hour.
Sample- and reference-solutions (approx. 0.2 ml) were loaded into the calorimeter (reference: buffer without enzyme) from storage conditions at 10° C. and thermally pre-equilibrated for 20 minutes at 20° C. prior to DSC scan from 20° C. to 100° C. Denaturation temperatures were determined at an accuracy of approximately +/−1° C.
The results demonstrated that the T. reesei wild-type cellobiohydrolase I has a Td of 69° C. compared to 68° C. for the cellobiohydrolase I M6 variant thereof.
Example 13: Site-Directed Mutagenesis of the Wild-Type Trichoderma reesei Cellobiohydrolase I
The codon-optimized synthetic gene encoding the wild-type T. reesei cellobiohydrolase I (Example 1) was used to generate the T. reesei cellobiohydrolase I TC1-111 variant (SEQ ID NO: 44 for the mutant DNA sequence and SEQ ID NO: 45 for the variant), an AAC codon (N198) was replaced with a GCA codon (198A).
To generate the T. reesei cellobiohydrolase I TC1-116 variant (SEQ ID NO: 46 for the mutant DNA sequence and SEQ ID NO: 47 for the variant), a GCC codon (A199) was deleted (A199*).
To generate the T. reesei cellobiohydrolase I TC1-61 variant (SEQ ID NO: 48 for the mutant DNA sequence and SEQ ID NO: 49 for the variant), an AAC codon (N200) was replaced with a TGG codon (200W).
To generate the T. reesei cellobiohydrolase I TC1-103 variant (SEQ ID NO: 50 for the mutant DNA sequence and SEQ ID NO: 51 for the variant), an AAC codon (N200) was replaced with a GGA codon (200G).
Two synthetic primers for each site-directed mutagenesis were designed as shown below using an SOE primer design tool. The introduced site-directed mutation changed an AAC codon (N198) to a GCA codon (198A), an AAC codon (N200) to a TGG codon (200W), and an AAC codon (N200) to a GGA codon (200G), and a GCC codon (A199) was deleted.
Primer F-N198A:
(SEQ ID NO: 52)
5′-GCTGGGAACCCTCGTCGAACGCAGCCAACACCGGCATTGGA-3′
Primer R-N198A:
(SEQ ID NO: 53)
5′-GTTCGACGAGGGTTCCCAGCCTTCGACGTTTG-3′
Primer F-ΔA199:
(SEQ ID NO: 54)
5′-TGGGAACCCTCGTCGAACAACAACACCGGCATTGGAGGCCAT-3′
Primer R-ΔA199:
(SEQ ID NO: 55)
5′-GTTGTTCGACGAGGGTTCCCAGCCTTCGACG-3′
Primer F-N200W:
(SEQ ID NO: 56)
5′-GAACCCTCGTCGAACAACGCCTGGACCGGCATTGGAGGCCATGG-3′
Primer R-N200W:
(SEQ ID NO: 57)
5′-GGCGTTGTTCGACGAGGGTTCCCAGCCTTCG-3′
Primer F-N200G:
(SEQ ID NO: 58)
5′-GAACCCTCGTCGAACAACGCCGGAACCGGCATTGGAGGCCAT-3′
Primer R-N200G:
(SEQ ID NO: 59)
5′-GGCGTTGTTCGACGAGGGTTCCCAGCCTTCG-3′
Site-directed mutagenesis of the synthetic gene encoding the wild-type T. reesei cellobiohydrolase was facilitated by PCR amplifications of the pDau109 vector containing the T. reesei cellobiohydrolase I gene: The T. reesei cellobiohydrolase I gene was previously cloned into Bam HI-Hind III digested pDau109 resulting in transcription of the T. reesei cellobiohydrolase I gene under the control of a NA2-tpi double promoter.
The mutations were introduced by PCR using a PHUSION® High-Fidelity PCR Kit. The PCR solution was composed of 10 μl of 5× HF buffer, 1 μl of dNTPs (10 mM), 0.5 μl of PHUSION® DNA polymerase (0.2 units/μl), 2.5 μl of primer F-N198A (10 μM), 2.5 μl of primer R-N198A (10 μM), 10 μl of template DNA (pDAu222- T. reesei cellobiohydrolase I, 1 ng/μl), and 23.5 μl of deionized water in a total volume of 50 μl. For the GCC deletion (A199* variant) 2.5 μl of primer F-ΔA199 (10 μM), 2.5 μl of primer R-ΔA199 (10 μM) were used. For the ACC to TGG mutation (N200W variant) 2.5 μl primer-F-N200W (10 μM) and 2.5 μl primer R-N200W (10 μM) were used. For the ACC to GGA mutation (N200G variant) 2.5 μl primer-F-N200G (10 μM) and 2.5 μl primer R-N200G (10 μM) were used.
The PCR was performed using a GeneAmp® PCR System 9700 (Applied Biosystems, Foster City, Calif., USA) programmed for 1 cycle at 98° C. for 30 seconds; and 19 cycles each at 98° C. for 30 seconds, 55° C. for 1 minute, and 72° C. for 4 minutes. The PCR solution was then held at 15° C. until removed from the PCR machine.
Following PCR, 10 units of Dpn I were added directly to the PCR solution and incubated at 37° C. for 1 hour. Then 1 μl of the Dpn I treated PCR solution was transformed into ONE SHOT® TOP10F′ Chemically Competent E. coli cells according to the manufacturer's protocol and spread onto LB plates supplemented with 0.15 mg of ampicillin per ml. After incubation at 37° C. overnight, transformants were observed growing under selection on the LB ampicillin plates. Two transformants were cultivated in LB medium supplemented with 0.15 mg of ampicillin per ml and plasmids were isolated using a QIAPREP® Spin Miniprep Kit.
The isolated plasmids were sequenced using an Applied Biosystems 3730xl DNA Analyzer with vector primers and T. reesei cellobiohydrolase 1 gene specific primers, shown below, in order to determine a representative plasmid that was free of PCR errors and contained the desired mutations.
Primer F-pDau109
(SEQ ID NO: 30)
5′-CCCTTGTCGATGCGATGTATC-3′
Primer F-Central1
(SEQ ID NO: 60)
5′-CATGTATCGTAAGCTCGCAGTCATCTCC-3′
Primer F-Central2
(SEQ ID NO: 61)
5′-CTTCGTGTCGATGGACGCGG-3′
Primer R-Central3
(SEQ ID NO: 62)
5′-GAACACGAGCCCCTCACTGC-3′
Primer R-pDau109
(SEQ ID NO: 31)
5′-ATCCTCAATTCCGTCGGTCGA-3′
One plasmid clone free of PCR errors and containing the AAC (N198) to GCA (198A) mutation was chosen and designated plasmid pN198A.
One plasmid clone free of PCR errors and containing the deletion of the GCC codon (A199) to (A199*) mutation was chosen and designated plasmid pΔA199.
One plasmid clone free of PCR errors and containing the AAC (N200) to TGG (200W) mutation was chosen and designated plasmid pN200W.
One plasmid clone free of PCR errors and containing the AAC (N200) to GGA (200G) mutation was chosen and designated plasmid pN200G.
pN198A was sequenced using primers F-Central1, F-Central2, R-Central3 and R-pDau109. pΔA199 was sequenced using primers F-pDau109 F-Central1, F-Central2, R-Central3 and R-pDau109. pN200W was sequenced using primers F-Central1, F-Central2 and R-pDau109. pN200G was sequenced using primers F-Central1, F-Central2 and R-pDau109
Example 14: Expression of the Trichoderma reesei Cellobiohydrolase I TC1-111, TC1-116, TC1-61, and TC1-103 Variants
Expression of plasmids pN198A, pΔA199, pN200W, and pN200G in Aspergillus oryzae MT3568 was performed according to the protocol described in Example 6.
Expression was verified by SDS-PAGE analysis using an E-Page 8% SDS-PAGE 48 well gel and Coomassie staining. Based on the level of expression by SDS-PAGE, one transformant was selected for each of plasmids pN198A, pΔA199, pN200W, and pN200G and designated Aspergillus oryzae ΔA199, N200G, N197A, and N200W, respectively.
For larger scale production, spores for each A. oryzae strain were spread onto COVE sucrose slants and incubated for five days at 37° C. Each confluent spore slant was washed twice with 5 ml of 0.01% TWEEN® 20 to maximize the number of spores collected. Each spore suspensions were then used to inoculate seven 500 ml flasks containing 150 ml of DAP-4C medium. The cultures were incubated at 30° C. with constant shaking at 100 rpm. At day four post-inoculation, the culture broths were collected by filtration through a bottle top MF75 Supor MachV 0.2 μm PES filter. Expression was verified by SDS-PAGE analysis using an E-Page 8% SDS-PAGE 48 well gel and Coomassie staining. The culture broths from each A. oryzae strain produced a band at approximately 80 kDa for the T. reesei A199*, N200G, N197A, and N200W cellobiohydrolase variant.
Example 15: Purification of the Trichoderma reesei Cellobiohydrolase I TC1-111, TC1-116, TC1-61, and TC1-103 Variants
The fermentation broths were filtered through PES Bottle top filter with a 0.22 μm cut-off (Thermo Fisher Scientific, Roskilde, Denmark). Ammonium sulphate was added to the filtered fermentation broths to make a 1.8 M solution.
The fermentation broths were purified by HIC/affinity chromatography followed by IEX/affinity chromatography.
In the HIC/affinity chromatographic step, the fermentation broths were applied to a 200 ml Phenyl SEPHAROSE® 6 Fast Flow column (high sub) equilibrated with 1.8 M ammonium sulphate, 25 mM HEPES pH 7.0. After applying the sample, the column was washed with 2 column volumes of 1.8 M ammonium sulphate followed by 1 column volume of 0.54 M ammonium sulphate. The bound proteins were batch eluted with 25 mM HEPES pH 7.0.
The elution of the protein was monitored at 280 nm. Fractions with high 280 nm absorbance were analyzed by SDS-PAGE using 12-well NUPAGE® 4-12% Bis-Tris gel for their cellobiohydrolase content. Fractions with high content of this protein were pooled and collected for further purification. The pooled fractions were desalted on a SEPHADEX™ G-25 (medium) column equilibrated with 25 mM MES pH 6.0. The elution of the protein was monitored at 280 nm and fractions with high absorbance at 280 nm were chosen for the second chromatographic step.
The pooled fractions were applied to the 60 ml RESOURCE™ 15Q column (equilibrated with 25 mM MES pH 6.0 and bound proteins were eluted with a linear 50-300 mM sodium chloride gradient for 3 column volumes. The elution of the protein was monitored at 280 nm and fractions with high absorbance at 280 nm were analysed on SDS-PAGE.
Fractions with high content of cellobiohydrolase I were pooled.
Example 16: Activity Measurement on Microcrystalline Cellulose of the Trichoderma Reesei Cellobiohydrolase I TC1-111, TC1-116, TC1-61, and TC1-103 Variants
The activity of the purified Trichoderma reesei cellobiohydrolase I TC1-111, TC1-116, TC1-61, and TC1-103 (variants were compared to the purified T. reesei wild-type cellobiohydrolase I using washed microcrystalline cellulose (AVICEL® PH101; Sigma-Aldrich, St. Louis, Mo., USA) as a substrate.
The washed microcrystalline cellulose was prepared by applying and mixing (by hand) 180 g of microcrystalline cellulose and approximately 400 ml of 0.22 μm filtered water to a centrifuge bottle (1 L). The centrifuge bottle was centrifuged at 4000 rpm for 5 minutes at 18° C. (Sorvall Hereaus Thermoscientific Sorvall Evolution RC superspeed centrifuge). The supernatant was removed and 400 ml of MQ water were added again. This was repeated 4 times. At the 4 th repeat the pellet and 0.22 μm filtered water were mixed on a “Rocker” o/n (IKA KS 130 basic) before centrifuging. The supernatant was removed and pellet was re-suspended with 50 mM sodium acetate, 2 mM CaCl 2 pH 5 buffer to a final concentration of 90 g/L.
The purified cellobiohydrolase variants were diluted in 50 mM sodium acetate, 2 mM CaCl 2 pH 5 to a concentration of 9 μM. Then 100 μl of the diluted cellobiohydrolase I variants were added to each well of a microtiter plate followed by 200 μl of washed microcrystalline cellulose at 90 g/liter to each well. The microtiter plate was quickly transferred to a thermomixer and incubated for 1 hour at 1100 rpm and 25° C. The reaction was stopped by centrifugation at 3500 rpm for 3 minutes at 5° C. using a HERAEUS® MULTIFUGE® 3 s-r centrifuge (Thermo Fisher Scientific, Roskilde, Denmark). Fifty μl of supernatant were transferred to PCR sample tubes (0.2 ml non-skirtet 96-well PCR plate; Thermo Fisher Scientific, Roskilde, Denmark). PAHBAH (4-hydroxy-benzhydrazide) was dissolved in buffer (0.18 M K—Na-tartrate and 0.5 M NaOH) to make a 15 mg/ml solution. Seventy-five μl of the PAHBAH solution were added to the supernatants in the PCR samples tubes.
The PCR sample tubes were placed in a Peltier Thermal Cycler and incubated at 95° C. for 10 minutes and 20° C. for 5 minutes. After incubation 100 μl were transferred to a 96 well microtiter plate and the absorbance was measured at 410 nm. For each run a standard was included. The standard used was cellobiose diluted in 50 mM sodium acetate, 2 mM CaCl 2 pH 5 to a concentration of 0.008, 0.016, 0.0312, 0.0625, 0.125, 0.25, 0.5, and 1 mM. In addition to the standard, a blank (without cellobiohydrolase) for each run was included. For all the measurements, the blank measurement was subtracted. The absorbance data were normalized to cellobiose concentration using the standards.
The results as shown in FIG. 5 demonstrated that the cellobiohydrolase A199* variant had an approximately 56% increase in activity toward microcrystalline cellulose compared to the wild-type cellobiohydrolase I. N200G variant had 40%, N198A had 23% and N200W had 3% increase in activity compared with wild-type cellobiohydrolase I.
Example 17: Pretreated Corn Stover Hydrolysis Assay
Corn stover was pretreated at the U.S. Department of Energy National Renewable Energy Laboratory (NREL) as described in Example 9.
Unmilled, unwashed PCS (whole slurry PCS) was prepared by adjusting the pH of the PCS to 5.0 by addition of 10 M NaOH with extensive mixing, and then autoclaving for 20 minutes at 120° C. The dry weight of the whole slurry PCS was 29%.
A 96-well plate was generated by machining a teflon plate of depth ¼ inch with 96, cone-shaped wells, diameter ¼ inch at the upper surface and diameter ⅛ inch at the lower surface. The center of each well was at an equivalent position to the center of a corresponding well in a standard 96-well microtiter plate, approximately 23/64 inch on center. The resulting volume of each well was approximately 135 μl. This 96-well aluminum plate is hereinafter referred to as the “fill plate”. The pH-adjusted unmilled, unwashed PCS was used to fill the holes in the fill plate by applying a suitable volume of the PCS to the upper surface of the plate, then using a spatula to spread the material over the surface and into the holes. Holes were deemed sufficiently full when the PCS was extruded through the hole in the bottom surface, forming noodle-like tubes. A MULTISCREEN® Column Loader Scraper (Millipore, Billerica, Mass., USA) held perpendicular to the fill plate surface was used to scrape excess PCS from the top and bottom surfaces of the fill plate, leaving the surfaces of the PCS in each well flush with the surfaces of the fill plate. The fill plate was then placed on the top of a 2.2 ml deep well plate (Axygen, Union City, Calif., USA) with the top surface adjacent to the open end of the well plate (e.g., the top of the well plate), and the wells aligned with the PCS-filled holes in the fill plate. The fill plate was secured in this position, and the assembly centrifuged at 2500 rpm (1350× g) for 5 minutes in a Sorvall Legend RT+(Thermo Scientific, Waltham, Mass., USA). Following centrifugation, the PCS had been transferred to the deep well plate. A 3 mm glass bead (Fisher Scientific, Waltham, Mass., USA) was placed in each well for mixing.
The hydrolysis of PCS was conducted in a total reaction volume of 0.2 ml. The hydrolysis was performed with 50 mg of insoluble PCS solids containing 50 mM sodium acetate pH 5.0 buffer containing 1 mM manganese sulfate and various protein loadings of various enzyme compositions (expressed as mg protein per gram of cellulose). Enzyme compositions were prepared and then added simultaneously to all wells in a volume ranging from 20 μl to 50 μl, for a final volume of 0.2-0.50 ml in each reaction. The plate was then sealed using an ALPS-300™ plate heat sealer, mixed thoroughly, and incubated at a specific temperature for 72 hours. All experiments reported were performed in triplicate.
Following hydrolysis, samples were filtered using a 0.45 μm MULTISCREEN® 96-well filter plate and filtrates analyzed for sugar content as described in Example 9.
Glucose was measured. The measured glucose concentration was adjusted for the appropriate dilution factor. The net concentration of enzymatically-produced glucose from unwashed PCS was determined by adjusting the measured glucose concentration for corresponding background glucose concentration in the unmilled, unwashed PCS at zero time point. All HPLC data processing was performed using MICROSOFT EXCEL™ software.
The degree of glucose conversion to glucose was calculated using the following equation: % glucose conversion=(glucose concentration)/(glucose concentration in a limit digest)×100. In order to calculate % glucose conversion, a 100% conversion point was set based on a cellulase control (100 mg of T. reesei cellulase per gram cellulose. Triplicate data points were averaged and standard deviation was calculated.
Example 18: Preparation of an Enzyme Composition #2 without Cellobiohydrolase I
An Aspergillus fumigatus GH6A cellobiohydrolase II variant (GENESEQP:AZN71803) was prepared recombinantly in Aspergillus oryzae as described in WO 2011/123450. The filtered broth of the A. fumigatus cellobiohydrolase II was desalted and buffer-exchanged into 50 mM sodium acetate pH 5.0 containing 100 mM sodium chloride using a tangential flow (10K membrane, Pall Corporation).
The Thermoascus aurantiacus GH5 endoglucanase II (GENESEQP:AZI04862) was prepared recombinantly according to WO 2011/057140 using Aspergillus oryzae as a host. The filtered broth of the T. aurantiacus endoglucanase II was concentrated using tangential flow (5K membrane, Pall Corporation). The concentrated protein was desalted using a 400 ml SEPHADEX™ G-25 column into 20 mM Tris pH 8.0.
The Penicillium sp. ( emersonii ) GH61A polypeptide was prepared as disclosed in Example 10.
The Aspergillus fumigatus GH10 xylanase (xyn3) was prepared as disclosed in Example 10.
The Aspergillus fumigatus Cel3A beta-glucosidase 4M mutant was prepared as described in Example 10. The protein concentration was determined using a Microplate BCA™ Protein Assay Kit (Thermo Fischer Scientific, Waltham, Mass., USA) in which bovine serum albumin was used as a protein standard.
The Talaromyces emersonii CBS 393.64 beta-xylosidase was prepared as described in Example 10.
The protein concentration for each of the monocomponents described above was determined using a Microplate BCA™ Protein Assay Kit in which bovine serum albumin was used as a protein standard, except the Penicillium sp. ( emersonii ) GH61A polypeptide, which was determined at A 280 using the theoretical molar extinction coefficient 41730 M −1 ·cm −1 . An enzyme composition was prepared composed of each monocomponent as follows: 39.7% Aspergillus fumigatus Cel6A variant cellobiohydrolase II, 15.9% T. reesei GH5 endoglucanase II, 23.8% Penicillium sp. ( emersonii ) GH61A polypeptide, 7.9% Aspergillus fumigatus GH10 xylanase, 7.9% Aspergillus fumigatus beta-glucosidase, and 4.8% Talaromyces emersonii beta-xylosidase. The enzyme composition is designated herein as “cellulolytic enzyme composition #2 without cellobiohydrolase I”.
Example 19: Source of DNA Sequence Information for Rasamsonia emersonii Cellobiohydrolase I
The genomic DNA sequence and deduced amino acid sequence of the wild-type Rasamsonia emersonii GH7 cellobiohydrolase I gene is shown in SEQ ID NO: 11 and SEQ ID NO: 12, respectively. The gene sequence is 99% identical to Genbank entry AF439935.4. The cDNA sequence and deduced amino acid sequence of the Rasamsonia emersonii cellobiohydrolase I gene is shown in SEQ ID NO: 63 and SEQ ID NO: 12, respectively.
Based on the cDNA sequence for Rasamsonia emersonii cellobiohydrolase I, a codon-optimized synthetic gene encoding the full-length cellobiohydrolase I was generated for Aspergillus oryzae expression based on the algorithm developed by Gustafsson et al., 2004 , Trends in Biotechnology 22 (7): 346-353. The codon-optimized coding sequence (SEQ ID NO: 64) was synthesized by the GENEART® Gene Synthesis service (Life Technologies Corp., San Diego. Calif., USA) with a 5′ Bam HI restriction site, a 3′ Hind III restriction site, and a Kozac consensus sequence (CACC) situated between the start codon and the Bam HI restriction site.
Example 20: Site-Directed Mutagenesis of the Wild-Type Rasamsonia emersonii Cellobiohydrolase I
The codon-optimized synthetic gene encoding the wild-type Rasamsonia emersonii cellobiohydrolase I was provided in a non-specified kanamycin-resistant E. coli cloning vector.
To generate the R. emersonii cellobiohydrolase I PC1-146 variant (SEQ ID NO: 65 for the mutant DNA sequence and SEQ ID NO: 66 for the variant), an AAC codon (N194) was replaced with a GCA codon (194A) and an AAC codon (N197) was replaced with a GCA codon (197A).
Two synthetic primers for site-directed mutagenesis were designed as shown below using a SOE primer design tool. The introduced site-directed mutation changed an AAC codon (N194) to a GCA codon (194A) and an AAC codon (N197) to a GCA codon (197A).
Primer F-N194A N197A:
(SEQ ID NO: 67)
5′-AAGGATGGCAGCCCTCGTCCGCAAACGCGGCAACTGGCATCGGTGAT
CAC-3′
Primer R-N194A N197A:
(SEQ ID NO: 68)
5′-GGACGAGGGCTGCCATCCTTCCACGTTCGC-3′
Site-directed mutagenesis of the synthetic gene encoding the wild-type R. emersonii cellobiohydrolase I was facilitated by PCR amplification of the pDau109 vector containing the R. emersonii cellobiohydrolase 1 gene designated pDau222- R. emersonii cellobiohydrolase I. The R. emersonii cellobiohydrolase 1 gene was previously cloned into Bam HI-Hind III digested pDau109 resulting in transcription of the R. emersonii cellobiohydrolase 1 gene under the control of a NA2-tpi double promoter.
The mutations were introduced by PCR using a PHUSION® High-Fidelity PCR Kit. The PCR solution was composed of 10 μl of 5× HF buffer, 1 μl of dNTPs (10 mM), 0.5 μl of PHUSION® DNA polymerase (0.2 units/μl), 0.25 μl of primer F-N194A N197A (100 μM), 0.25 μl of primer R-N194A N197A (100 μM), 10 μl of template DNA (pDau222- R. emersonii cellobiohydrolase I, 1 ng/μl), and 28 μl of deionized water in a total volume of 50 μl. The PCR was performed using a GeneAmp® PCR System 9700 (Applied Biosystems, Foster City, Calif., USA) programmed for 1 cycle at 98° C. for 30 seconds; and 19 cycles each at 98° C. for 30 seconds, 55° C. for 1 minute, and 72° C. for 4 minutes. The PCR solution was then held at 8° C. until removed from the PCR machine.
Following PCR, 10 units of Dpn I were added directly to the PCR solution and incubated at 37° C. for 1 hour. Then 1 μl of the Dpn I treated PCR solution was transformed into ONE SHOT® TOP10F′ Chemically Competent E. coli cells according to the manufacturer's protocol and spread onto LB plates supplemented with 0.15 mg of ampicillin per ml. After incubation at 37° C. overnight, transformants were observed growing under selection on the LB ampicillin plates. Four transformants were cultivated in LB medium supplemented with 0.15 mg of ampicillin per ml and plasmids were isolated using a QIAPREP® Spin Miniprep Kit.
The isolated plasmids were sequenced using an Applied Biosystems 3730xl DNA Analyzer with vector primers and R. emersonii cellobiohydrolase 1 gene specific primers, shown below, in order to determine a representative plasmid that was free of PCR errors and contained the desired mutations.
Primer F-pDau109
(SEQ ID NO: 69)
5′-CCACACTTCTCTTCCTTCCTCAATCCTC-3′
Primer F-Central1
(SEQ ID NO: 70)
5′-GTGAGGCGAACGTGGAAGGATG-3′
Primer R-Central2
(SEQ ID NO: 71)
5′-gtacctgtgtccgtgccgtcatctg-3′
Primer R-pDau109
(SEQ ID NO: 31)
5′-ATCCTCAATTCCGTCGGTCGA-3′
One plasmid clone free of PCR errors and containing the AAC (N194) to GCA (194A) mutation and the AAC (N197) to GCA (197A) mutation was chosen and designated plasmid pE146. The variant is designated herein as PC1-146.
Example 21: Construction of an Aspergillus oryzae Expression Vector Containing a Rasamsonia emersonii DNA Sequence Encoding Cellobiohydrolase I
The kanamycin-resistant E. coli cloning vector provided by GENEART® Gene Synthesis encoding the Rasamsonia emersonii cellobiohydrolase I was digested with Fast Digest Bam HI and Hind III (Fermentas Inc., Glen Burnie, Md., USA) according to manufacturer's instructions. The reaction products were isolated by 1.0% agarose gel electrophoresis using TAE buffer where a 1375 bp product band was excised from the gel and purified using an ILLUSTRA™ GFX™ DNA Purification Kit.
The 1375 bp fragment was then cloned into pDau109 digested with Bam HI and Hind III using T4 DNA ligase. The Bam HI-Hind III digested pDau109 and the Bam HI/Hind III fragment containing the T. reesei cellobiohydrolase I coding sequence were mixed in a molar ratio of 1:3 (i.e., mass ratio approximately 2.5:1 or 20 ng:50 ng) and ligated with 50 units of T4 DNA ligase in 1× T4 DNA ligase buffer with 1 mM ATP at 16° C. over-night in accordance with the manufacturer's instructions. Cloning of the Rasamsonia emersonii cellobiohydrolase I gene into Bam HI-Hind III digested pDau109 resulted in the transcription of the Rasamsonia emersonii cellobiohydrolase I gene under the control of a NA2-tpi double promoter.
The ligation mixture was transformed into ONE SHOT® TOP10F′ Chemically Competent E. coli cells according to the manufacturer's protocol and spread onto LB plates supplemented with 0.1 mg of ampicillin per ml. After incubation at 37° C. overnight, transformants were observed growing under selection on the LB ampicillin plates. Insertion of the Rasamsonia emersonii cellobiohydrolase I gene into pDau109 was verified by PCR on the transformants as described below using primers F-pDau109 and R-pDau109.
A 1.1× REDDYMIX® Master Mix (Thermo Fisher Scientific, Roskilde, Denmark) was used for the PCR. The PCR solution was composed of 10 μl of 1.1× REDDYMIX® Master Mix, 0.5 μl of primer F-pDau109 (10 μM), and 0.5 μl of primer R-pDau109 (10 μM). A toothpick was used to transfer a small amount of cells to the PCR solution. The PCR was performed using a PTC-200 DNA Engine programmed for 1 cycle at 94° C. for 3 minutes; 30 cycles each at 94° C. for 30 seconds, 50° C. for 1 minute, and 72° C. for 2 minutes; and 1 cycle at 72° C. for 1 minute. The PCR solution was then held at 15° C. until removed from the PCR machine.
The PCR products were analyzed by 1.0% agarose gel electrophoresis using TAE buffer where a 1600 bp PCR product band was observed confirming insertion of the Rasamsonia emersonii cellobiohydrolase I coding sequence into pDau109.
An E. coli transformant containing the Rasamsonia emersonii cellobiohydrolase I plasmid construct was cultivated in LB medium supplemented with 0.1 mg of ampicillin per ml and plasmid DNA was isolated using a QIAPREP® Spin Miniprep Kit. The plasmid was designated pKHJN0135.
Example 22: Expression of the Wild-Type Rasamsonia emersonii Cellobiohydrolase I
The expression plasmid pKHJN0135 was transformed into Aspergillus oryzae MT 3568 protoplasts according to Christensen et al., 1988, supra and WO 2004/032648. A. oryzae MT3568 protoplasts were prepared according to the method of EP 0238023 B1, pages 14-15.
Transformants were purified on COVE sucrose plates through single conidia prior to sporulating them on PDA plates. Spores of the transformants were inoculated into 96 deep well plates containing 0.75 ml of YP+2% glucose medium and incubated stationary at 30° C. for 4 days. Production of the Rasamsonia emersonii cellobiohydrolase I by the transformants was analyzed from culture supernatants of the 96 deep well cultivations. Expression was verified by SDS-PAGE analysis using an E-Page 8% SDS-PAGE 48 well gel and Coomassie blue staining. Based on the level of expression by SDS-PAGE, one transformant was selected for further work and designated Aspergillus oryzae ReCBH I.
For larger scale production, A. oryzae ReCBH I spores were spread onto COVE sucrose slants and incubated for five days at 37° C. The confluent spore slants were washed twice with 5 ml of 0.01% TWEEN® 20 to maximize the number of spores collected. The spore suspensions were then used to inoculate seven 500 ml flasks containing 150 ml of DAP-4C medium. The cultures were incubated at 30° C. with constant shaking at 100 rpm. At day four post-inoculation, the culture broths were collected by filtration through a bottle top MF75 Supor MachV 0.2 μm PES filter. Expression was verified by SDS-PAGE analysis using an E-Page 8% SDS-PAGE 48 well gel and Coomassie staining. The culture broths from A. oryzae ReCBH I produced a band at approximately 60 kDa for the Rasamsonia emersonii cellobiohydrolase I.
For larger scale production, A. oryzae ReCBH I spores were spread onto COVE sucrose slants and incubated for five days at 37° C. The confluent spore slants were washed twice with 5 ml G2-Gly medium. The spore suspensions were then used to inoculate 500 ml flasks containing 150 ml of G2-Gly medium. These pre-cultures were incubated at 30° C. with constant shaking at 150 rpm. After one day, each of the pre-cultures was used to inoculate four 500 ml flasks containing 150 ml DAP4C-1 medium. At day four post-inoculation, the culture broths were collected by filtration through a bottle top MF75 Supor MachV 0.2 μm PES filter.
Example 23: Expression of the Rasamsonia emersonii Cellobiohydrolase I PC1-146 Variant
The expression plasmid pE146 was transformed into Aspergillus oryzae MT3568 protoplasts according to Christensen et al., 1988, supra and WO 2004/032648. A. oryzae MT3568 protoplasts were prepared according to the method of EP 0238023 B1, pages 14-15.
Transformants were purified on COVE sucrose plates without CsCl through single conidia. Spores of the transformants were inoculated into 96 deep well plates containing 0.50 ml of YP+2% maltose medium and incubated stationary at 34° C. for 6 days. Production of the R. emersonii cellobiohydrolase I PC1-146 variant by the transformants was analyzed from culture supernatants of the 96 deep well cultivations. Expression was verified by measuring released reducing sugars from hydrolysis of microcrystalline cellulose. The hydrolysis was performed in 96 well microtiter plates (NUNC Thermo Fisher Scientific, Roskilde, Denmark) at 25° C. and 1100 rpm. Each hydrolysis reaction mixture contained 167 μl of microcrystalline cellulose at 90 g/liter in 50 mM sodium acetate pH 5.0, 0.01% TRITON® X-100, 20 μl of culture supernatant, and 63 μl of 50 mM sodium acetate pH 5.0, 0.01% TRITON® X-100. The plates were sealed with tape. The hydrolysis reaction was stopped by spinning the plate at 3500 rpm for 3 minutes. Then 50 μl of the reaction supernatant were added to 75 μl of stop solution in a 96 well PCR plate (Thermo Fisher Scientific, Roskilde, Denmark). The stop solution was composed of 15 mg/ml 4-hydroxybenzhydrazide (Sigma Chemical Co., Inc., St. Louis, Mo., USA), 50 mg/ml K—Na-tartrate (Sigma Chemical Co., Inc., St. Louis, Mo., USA) in 2% (w/v) NaOH. The plate was sealed with a lid and the mixture was incubated at 95° C. for 10 minutes and 5 minutes at 20° C. Then 100 μl was transferred to a microtiter plate and absorbance at 410 nm was measured using a SPECTRAMAX® Plus 384 (Molecular Devices, Sunnyvale, Calif., USA). The concentration of reducing sugar was proportional to the absorbance at 410 nm of the oxidized 4-hydroxybenzhydrazide. The reducing sugar content in the culture supernatants was measured by adding 4 μl of culture supernatant to a mixture of 75 μl of stop solution and 46 μl of milliQ water in a 96 well PCR plate. The plate was sealed with a lid and the mixture was incubated at 95° C. for 10 minutes and 5 minutes at 20° C. Then 100 μl was transferred to a microtiter plate and the absorbance at 410 nm was measured. The absorbance at 410 nm from the cell culture supernatant was subtracted from the absorbance at 410 nm of the hydrolysis reaction, to measure the amount of reducing sugar released by the enzymes.
Based on the level of hydrolysis of the microcrystalline cellulose one transformant was selected and designated A. oryzae PC1-146.
For larger scale production, A. oryzae PC1-146 spores were spread onto COVE sucrose slants and incubated for five days at 37° C. The confluent spore slants were washed twice with 5 ml of G2-Gly medium. The spore suspensions were then used to inoculate 500 ml flasks containing 150 ml of G2-Gly medium. These pre-cultures were incubated at 30° C. with constant shaking at 150 rpm. After one day, each of the pre-cultures was used to inoculate four 500 ml flasks containing 150 ml of DAP-4C medium. At day four post-inoculation, the culture broths were collected by filtration through a bottle top MF75 Supor MachV 0.2 μm PES filter.
Example 24: Purification of the Rasamsonia emersonii Wild-Type Cellobiohydrolase I and R. emersonii Cellobiohydrolase I PC1-146 Variant
The fermentation broths were filtered through a PES Bottle top filter with a 0.22 μm cut-off. Ammonium sulphate was added to the filtered fermentation broths to a concentration of 1.8 M. The fermentation broths were purified by HIC/affinity chromatography followed by IEX/affinity chromatography.
In the HIC/affinity chromatographic step, the fermentation broths were applied to a 200 ml Phenyl SEPHAROSE® 6 Fast Flow column (high sub) equilibrated with 1.8 M ammonium sulphate, 25 mM HEPES pH 7.0. After applying the sample, the column was washed with 2 column volumes of 1.8 M ammonium sulphate followed by 1 column volume of 0.54 M ammonium sulphate. The bound proteins were batch eluted with 25 mM HEPES pH 7.0.
The elution of the protein was monitored at 280 nm. Fractions with high 280 nm absorbance were analyzed by SDS-PAGE using 12-well NUPAGE® 4-12% Bis-Tris gel for their cellobiohydrolase content. Fractions with high content of the protein were pooled and collected for further purification. The pooled fractions were desalted on a SEPHADEX™ G-25 (medium) column equilibrated with 25 mM MES pH 6.0. The elution of the protein was monitored at 280 nm and fractions with high absorbance at 280 nm were chosen for the second chromatographic step.
The pooled fractions were applied to a 60 ml RESOURCE™ 15Q column equilibrated with 25 mM MES pH 6.0 and bound proteins were eluted with a linear 100-200 mM sodium chloride gradient for 1.5 column volumes followed by 1.5 column volumes of 300 mM sodium chloride, and followed by 1.5 column volumes of 1 M sodium chloride. The elution of the protein was monitored at 280 nm and fractions with high absorbance at 280 nm were analyzed on SDS-PAGE. Fractions with high content of cellobiohydrolase I were pooled.
Example 25: Activity Measurement on Microcrystalline Cellulose of the Rasamsonia Emersonii Cellobiohydrolase I PC1-146 Variant
The activity of the purified R. emersonii cellobiohydrolase I PC1-146 variant was compared to the purified T. reesei wild-type cellobiohydrolase I using washed microcrystalline cellulose (AVICEL® PH101; Sigma-Aldrich, St. Louis, Mo., USA) as a substrate.
The purified cellobiohydrolase variant was diluted in 50 mM sodium acetate, 2 mM CaCl 2 pH 5 to a concentration of 0.4 μM. Then 50 μl of the diluted cellobiohydrolase I variant were added to each well of a microtiter plate followed by 200 μl of washed microcrystalline cellulose at 90 g/liter to each well. The microtiter plate was quickly transferred to a thermomixer and incubated for 1 hour at 1100 rpm and 50° C. The reaction was stopped by centrifugation at 3500 rpm for 3 minutes at 5° C. using a HERAEUS® MULTIFUGE® 3 s-r centrifuge. Fifty μl of supernatant were transferred to PCR sample tubes (0.2 ml non-skirtet 96-well PCR plate). PAHBAH (4-hydroxy-benzhydrazide) was dissolved in buffer (0.18 M K—Na-tartrate and 0.5 M NaOH) to make a 15 mg/ml solution. Seventy-five μl of the PAHBAH solution were added to the supernatants in the PCR samples tubes.
The PCR sample tubes were placed in a Peltier Thermal Cycler and incubated at 95° C. for 10 minutes and 20° C. for 5 minutes. After incubation 100 μl were transferred to a 96 well microtiter plate and the absorbance was measured at 410 nm. For each run a standard was included. The standard used was cellobiose diluted in 50 mM sodium acetate, 2 mM CaCl 2 pH 5 to a concentration of 0.008, 0.016, 0.0312, 0.0625, 0.125, 0.25, 0.5, and 1 mM. In addition to the standard, a blank (without cellobiohydrolase) for each run was included. For all the measurements, the blank measurement was subtracted. The absorbance data were normalized to cellobiose concentration using the standards.
The results as shown in FIG. 6 demonstrated that the R. emersonii cellobiohydrolase I PC1-146 variant had an approximately 17% increase in activity toward microcrystalline cellulose compared to the R. emersonii wild-type cellobiohydrolase I.
Example 26: Determination of Td of the Rasamsonia emersonii Cellobiohydrolase I PC1-146 Variant by Differential Scanning Calorimetry
The thermostability of the R. emersonii cellobiohydrolase I PC1-146 variant was determined by Differential Scanning calorimetry (DSC) using a VP-Capillary Differential Scanning calorimeter as described in Example 12.
The results demonstrated that the R. emersonii wild-type cellobiohydrolase I has a Td of 78° C. compared to 78° C. for the R. emersonii cellobiohydrolase I PC1-146 variant thereof.
Example 27: Comparison of the Effect of Rasamsonia emersonii Cellobiohydrolase I PC1-146 Variant and Rasamsonia emersonii Wild-Type Cellobiohydrolase I on the Hydrolysis of Unwashed PCS by a Cellulase Enzyme Composition
The R. emersonii cellobiohydrolase I PC1-146 variant and R. emersonii wild-type cellobiohydrolase I were added to cellulolytic enzyme composition #2 without cellobiohydrolase I (Example 18) at 25° C. using unmilled, unwashed PCS as a substrate. For hydrolysis at 8% total solids, each cellobiohydrolase I was added individually at 2.22 mg enzyme protein per g cellulose to 3.78 mg enzyme protein of the cellulase enzyme composition #2 without cellobiohydrolase I per g cellulose. For hydrolysis as 20% total solids, each cellobiohydrolase I was added individually at 4.44 mg enzyme protein per g cellulose to 7.56 mg enzyme protein of the cellulase enzyme composition #2 without cellobiohydrolase I per g cellulose.
The assay was performed as described in Example 17. The reactions with unmilled, unwashed PCS (8% and 20% total solids) were conducted for 24, 48, and 72 hours in 50 mM sodium acetate pH 5.0 buffer containing 1 mM manganese sulfate. All reactions were performed in quadruplicate and shaking at 200 rpm throughout the hydrolysis.
The results shown in FIG. 7 (8% total solids) and FIG. 8 (20% total solids) demonstrated that at 24, 48, and 72 hours, the cellulase enzyme composition that included the R. emersonii cellobiohydrolase I PC1-146 variant had significantly higher cellulose conversion than the cellulase enzyme composition that included R. emersonii wild-type cellobiohydrolase I.
Example 28: Comparison of Rasamsonia emersonii Cellobiohydrolase I PC1-146 Variant with Rasamsonia emersonii Wild-Type Cellobiohydrolase I During Hydrolysis
Evaluation of the R. emersonii cellobiohydrolase I PC1-146 variant and the R. emersonii wild-type cellobiohydrolase I was performed on unmilled, unwashed PCS at 20% TS. The enzyme matrix design is shown below in Table 1. CELLIC® HTec3 was obtained from Novozymes A/S, Bagsvaerd, Denmark. Enzymatic hydrolysis was conducted at 32° C. for 3 and 5 days. The sugar released was analyzed by HPLC (1200 Series LC System, Agilent Technologies Inc., Palo Alto, Calif., USA) equipped with a Rezex ROA-Organic acid H + column (8%) (7.8×300 mm) (Phenomenex Inc., Torrance, Calif., USA), 0.2 mm in line filter, an automated sampler, a gradient pump and a refractive index detector. The mobile phase used was 5 mM sulfuric acid at a flow rate of 0.9 ml/min. Glucose at different concentrations was used as standards.
The results as shown in FIG. 9 demonstrated that the R. emersonii cellobiohydrolase I PC1-146 variant performed better than the wild-type R. emersonii cellobiohydrolase I.
TABLE 1
en-
zyme
dose
R.
R.
mg/g
emersonii
emersonii
Af
glu-
CBH I
CBH I
CBH
Ta
Aa
CELLIC ®
Tube
can
Variant
Wild-type
II
EG
BG
Htec3
1
6
37.5%
37.5%
10%
5%
10%
2
6
37.5%
37.5%
10%
5%
10%
Example 29: Comparison of Rasamsonia emersonii Cellobiohydrolase I PC1-146 Variant with Rasamsonia emersonii Wild-Type Cellobiohydrolase I During Simultaneous Saccharification and Fermentation (SSF)
The experimental design was the same as shown in Example 28, except that RED STAR® yeast at 1 g per liter and urea at 2 g per liter were added together with the enzyme during the beginning of the hydrolysis. Ethanol release was analyzed by HPLC using the system described in Example 28. Ethanol at different concentrations was used as standards.
The results as shown in FIG. 10 demonstrate that the R. emersonii cellobiohydrolase I PC1-146 variant performed better than the wild-type R. emersonii cellobiohydrolase I during SSF.
Example 30: Construction of a Rasamsonia emersonii Fusion Cellobiohydrolase I with Linker and Carbohydrate Binding Module from Trichoderma reesei Cellobiohydrolase I
The codon-optimized synthetic gene encoding the T. reesei ( H. jecorina ) cellobiohydrolase I is described in Example 1.
The codon-optimized synthetic gene encoding the R. emersonii cellobiohydrolase I is described in Example 19.
To generate a gene encoding a R. emersonii fusion cellobiohydrolase I with linker and carbohydrate binding module (CBM) from T. reesei cellobiohydrolase I (SEQ ID NO: 72 for the fusion protein DNA sequence and SEQ ID NO: 73 for the fusion protein), a DNA fragment encoding T. reesei cellobiohydrolase I linker and CBM was assembled to the 3′-end of the gene encoding the R. emersonii cellobiohydrolase I using splicing overlap extension (SOE) PCR.
The DNA fragment encoding the T. reesei cellobiohydrolase I linker and CBM was amplified using primer F-SOE and primer R-pDau109 shown below.
Primer F-SOE
(SEQ ID NO: 74)
5′-GGTCCCATCAACTCGACATTCACAGCCTCGGGTGGAAACCCTCCTGG
CGGAAACCCTC-3′
Primer R-pDau109
(SEQ ID NO: 31)
5′-ATCCTCAATTCCGTCGGTCGA-3′
Primer F-pDau109
(SEQ ID NO: 69)
5′-CCACACTTCTCTTCCTTCCTCAATCCTC-3′
The amplification of the DNA fragment encoding the T. reesei cellobiohydrolase 1 linker and CBM was performed using a PHUSION® High-Fidelity PCR Kit. The PCR solution was composed of 10 μl of 5× HF buffer, 1 μl of dNTPs (10 mM), 0.5 μl of PHUSION® DNA polymerase (0.2 units/μl), 0.25 μl of primer F-SOE (100 μM), 0.25 μl of primer R-pDau109 (100 μM), 10 μl of template DNA (pDAu222- T. reesei cellobiohydrolase I, 1 ng/μl), and 28 μl of deionized water in a total volume of 50 μl. The PCR was performed using a GeneAmp® PCR System 9700 programmed for 1 cycle at 98° C. for 30 seconds; and 30 cycles each at 98° C. for 10 seconds, 55° C. for 30 seconds, and 72° C. for 1 minute. The PCR solution was then held at 8° C. until removed from the PCR machine.
The PCR solution was submitted to 1% agarose gel electrophoresis using TAE buffer where a 405 bp PCR fragment encoding the T. reesei a linker and CBM was excised from the gel and purified using a MinElute Gel Extraction Kit (QIAGEN Inc., Valencia, Calif., USA).
A DNA fragment encoding the R. emersonii cellobiohydrolase I was amplified using primer F-pDau109 and primer R-pDau109 above.
The amplification of the DNA fragment encoding the R. emersonii wild-type cellobiohydrolase I was performed using a PHUSION® High-Fidelity PCR Kit. The PCR solution was composed of 10 μl of 5× HF buffer, 1 μl of dNTPs (10 mM), 0.5 μl of PHUSION® DNA polymerase (0.2 units/μl), 0.25 μl of primer F-pDAu109 (100 μM), 0.25 μl of primer R-pDau109 (100 μM), 10 μl of template DNA (pDAu222- R. emersonii cellobiohydrolase I, 1 ng/μl), and 28 μl of deionized water in a total volume of 50 μl. The PCR was performed using a GeneAmp® PCR System 9700 programmed for 1 cycle at 98° C. for 30 seconds; and 30 cycles each at 98° C. for 10 seconds, 55° C. for 30 seconds, and 72° C. for 1 minute. The PCR solution was then held at 8° C. until removed from the PCR machine.
The PCR solution was submitted to 1% agarose gel electrophoresis using TAE buffer where a 1600 bp fragment encoding the R. emersonii wild-type cellobiohydrolase I was excised from the gel and purified using a MinElute Gel Extraction Kit.
The two purified DNA fragments were assembled using SOE PCR and a PHUSION® High-Fidelity PCR Kit. The PCR solution was composed of 10 μl of 5× HF buffer, 1 μl of dNTPs (10 mM), 0.5 μl of PHUSION® DNA polymerase (0.2 units/μl), 0.25 μl of primer F-pDAu109 (100 μM), 10 μl of gel purified fragment encoding T. reesei cellobiohydrolase 1 linker and CBM, 2 μl of DNA fragment encoding R. emersonii cellobiohydrolase I, and 26 μl of deionized water in a total volume of 50 μl. The PCR was performed using a GeneAmp® PCR System 9700 programmed for 1 cycle at 98° C. for 30 seconds; and 30 cycles each at 98° C. for 20 seconds, 55° C. for 30 seconds, and 72° C. for 1 minute. The PCR solution was then held at 8° C. until removed from the PCR machine.
The PCR generated DNA fragment was then digested with Bam HI (New England Biolabs, Ipswich, Mass., USA) and Hind III (New England Biolabs, Ipswich, Mass., USA) as follows. Forty μl of PCR product were mixed with 5 μl buffer 2 (New England Biolabs, Ipswich, Mass., USA), 1 μl of Bam HI, and 1 μl of Hind III and incubated for 4 hours at 37° C. The resulting DNA product was submitted to 1% agarose gel electrophoresis using TAE buffer. A band of approximately 1567 bp was excised from the gel and purified using a MinElute Gel Extraction Kit.
The purified 1567 bp fragment encoding the R. emersonii cellobiohydrolase I with linker and carbohydrate binding module (CBM) from T. reesei cellobiohydrolase I was cloned into pDAu109 digested with Bam HI and Hind III using T4 DNA ligase. The Bam HI-Hind III digested pDau109 and the Bam HI/Hind III fragment containing the R. emersonii cellobiohydrolase I with linker and carbohydrate binding module (CBM) from T. reesei cellobiohydrolase I coding sequence were mixed in a molar ratio of 1:3 (i.e., equal volumes of gel purified products) and ligated with 50 units of T4 DNA ligase in 1× T4 DNA ligase buffer with 1 mM ATP and incubated at 22° C. for 10 minutes.
The ligation mixture was transformed into ONE SHOT® TOP10F′ Chemically Competent E. coli cells according to the manufacturer's protocol and spread onto LB plates supplemented with 0.1 mg of ampicillin per ml. After incubation at 37° C. overnight, transformants were observed growing under selection on the LB ampicillin plates. Two transformants were cultivated in LB medium supplemented with 0.15 mg of ampicillin per ml and plasmids were isolated using a QIAPREP® Spin Miniprep Kit.
The insertion of the DNA fragment encoding the R. emersonii cellobiohydrolase I with linker and carbohydrate binding module (CBM) from T. reesei cellobiohydrolase I into pDAu109 was verified by sequencing. The isolated plasmids were sequenced using an Applied Biosystems 3730xl DNA Analyzer with vector primers F-pDau109 and R-pDau109 in order to determine a representative plasmid that was free of PCR errors and contained the correct insertion.
One plasmid clone free of PCR errors and containing the DNA fragment encoding the R. emersonii cellobiohydrolase I with linker and carbohydrate binding module (CBM) from T. reesei cellobiohydrolase I was chosen and designated plasmid pE147. The fusion cellobiohydrolase I is designated herein as PC1-147.
Example 31: Site-Directed Mutagenesis of the Rasamsonia emersonii PC1-147 Fusion Cellobiohydrolase I
The fusion protein gene encoding the R. emersonii PC1-147 fusion cellobiohydrolase I was provided in pE147.
To generate a variant of the R. emersonii PC1-147 fusion cellobiohydrolase I (SEQ ID NO: 75 for the mutant DNA sequence and SEQ ID NO: 76 for the variant), an AAC codon (N194) was replaced with a GCA codon (194A) and an AAC codon (N197) was replaced with a GCA codon (197A) in the gene encoding the R. emersonii PC1-147 fusion cellobiohydrolase I.
Two synthetic primers for site-directed mutagenesis were designed as shown below using a SOE primer design tool. The introduced site-directed mutation changed an AAC codon (N194) to a GCA codon (194A) and an AAC codon (N197) to a GCA codon (197A).
Primer F-N194A N197A:
(SEQ ID NO: 67)
5′-AAGGATGGCAGCCCTCGTCCGCAAACGCGGCAACTGGCATCGGTG
ATCAC-3′
Primer R-N194A N197A:
(SEQ ID NO: 68)
5′-GGACGAGGGCTGCCATCCTTCCACGTTCGC-3′
Site-directed mutagenesis of the R. emersonii PC1-147 fusion cellobiohydrolase I gene was facilitated by PCR amplifications of the pDau109 vector containing the R. emersonii PC1-147 fusion cellobiohydrolase I gene. The R. emersonii PC1-147 fusion cellobiohydrolase I gene was previously cloned into Bam HI-Hind III digested pDau109 resulting in transcription of the R. emersonii PC1-147 fusion cellobiohydrolase I gene under the control of a NA2-tpi double promoter.
The mutations were introduced by PCR using a PHUSION® High-Fidelity PCR Kit. The PCR solution was composed of 10 μl of 5× HF buffer, 1 μl of dNTPs (10 mM), 0.5 μl of PHUSION® DNA polymerase (0.2 units/μl), 0.25 μl of primer F-N194A N197A (100 μM), 0.25 μl of primer R-N194A N197A (100 μM), 10 μl of plasmid pE147 DNA (1 ng/μl), and 28 μl of deionized water in a total volume of 50 μl. The PCR was performed using a GeneAmp® PCR System 9700 programmed for 1 cycle at 98° C. for 30 seconds; and 19 cycles each at 98° C. for 30 seconds, 55° C. for 1 minute, and 72° C. for 4 minutes. The PCR solution was then held at 8° C. until removed from the PCR machine.
Following the PCR, 10 units of Dpn I were added directly to the PCR solution and incubated at 37° C. for 1 hour. Then 1 μl of the Dpn I treated PCR solution was transformed into ONE SHOT® TOP10F′ Chemically Competent E. coli cells according to the manufacturer's protocol and spread onto LB plates supplemented with 0.15 mg of ampicillin per ml. After incubation at 37° C. overnight, transformants were observed growing under selection on the LB ampicillin plates. Four transformants were cultivated in LB medium supplemented with 0.15 mg of ampicillin per ml and plasmids were isolated using a QIAPREP® Spin Miniprep Kit.
The isolated plasmids were sequenced using an Applied Biosystems 3730xl DNA Analyzer with primers F-pDau109, F-Central1, R-Central2 and R-pDau109, in order to determine a representative plasmid that was free of PCR errors and contained the desired mutations.
Primer F-pDau109
(SEQ ID NO: 69)
5′-CCACACTTCTCTTCCTTCCTCAATCCTC-3′
Primer F-Central1
(SEQ ID NO: 70)
5′-GTGAGGCGAACGTGGAAGGATG-3′
Primer R-Central2
(SEQ ID NO: 71)
5′-gtacctgtgtccgtgccgtcatctg-3′
Primer R-pDau109
(SEQ ID NO: 31)
5′-ATCCTCAATTCCGTCGGTCGA-3′
One plasmid clone free of PCR errors and containing the AAC (N194) to GCA (194A) mutation and the AAC (N197) to GCA (197A) mutation was chosen and designated plasmid pE378. The variant is designated herein as PC1-378.
Example 32: Expression of the Rasamsonia emersonii PC1-147 Fusion Cellobiohydrolase I and R. emersonii Cellobiohydrolase I PC1-378 Variant
The expression plasmids pE147 and pE378 were transformed into Aspergillus oryzae MT3568 protoplasts according to Christensen et al., 1988, supra and WO 2004/032648. A. oryzae MT3568 protoplasts were prepared according to the method of EP 0238023 B1, pages 14-15.
Transformants were purified on COVE sucrose plates without CsCl through single conidia. Spores of the transformants were inoculated into 96 deep well plates containing 0.50 ml of YP+2% maltose+0.5% glucose medium and incubated stationary at 34° C. for 6 days. Production of the R. emersonii PC1-147 fusion cellobiohydrolase I and the R. emersonii cellobiohydrolase I PC1-378 variant by the transformants were analyzed from culture supernatants of the 96 deep well cultivations. Expression was verified by measuring the released reducing sugars from hydrolysis of microcrystalline cellulose according to the procedure described in Example 23.
Based on the level of hydrolysis of the microcrystalline cellulose one transformant for the R. emersonii PC1-147 fusion cellobiohydrolase I and the R. emersonii cellobiohydrolase I PC1-378 variant were selected and designated A. oryzae PC1-147 and A. oryzae PC1-378, respectively.
For larger scale production, A. oryzae PC1-147 or A. oryzae PC1-378 spores were spread onto COVE sucrose slants and incubated for five days at 37° C. The confluent spore slants were washed twice with 5 ml of G2-Gly medium. The spore suspensions were then used to inoculate 500 ml flasks containing 150 ml of G2-Gly medium. These pre-cultures were incubated at 30° C. with constant shaking at 150 rpm. After one day, each of the pre-cultures was used to inoculate four 500 ml flasks containing 150 ml of DAP-4C medium. At day four post-inoculation, the culture broths were collected by filtration through a bottle top MF75 Supor MachV 0.2 μm PES filter.
Example 33: Purification of the Rasamsonia emersonii PC1-147 Fusion Cellobiohydrolase I and R. emersonii Cellobiohydrolase I PC1-378 Variant
The fermentation broths were filtered through a PES Bottle top filter with a 0.22 μm cut-off. Ammonium sulphate was added to the filtered fermentation broths to a concentration of 1.8 M.
The fermentation broths were purified by HIC/affinity chromatography followed by IEX/affinity chromatography.
In the HIC/affinity chromatographic step, the fermentation broths were applied to a 200 ml Phenyl SEPHAROSE® 6 Fast Flow column (high sub) which had been pre-equilibrated with 1.8 M ammonium sulphate, 25 mM HEPES pH 7.0. After applying the sample, the column was washed with 2 column volumes of 1.8 M ammonium sulphate followed by 1 column volume of 0.54 M ammonium sulphate. The bound proteins were batch eluted with 25 mM HEPES pH 7.0.
The elution of the protein was monitored at 280 nm. Fractions with high 280 nm absorbance were analysed on SDS-PAGE using 12-well NUPAGE® 4-12% Bis-Tris gel for their cellobiohydrolase I content. Fractions with high content of this protein were pooled and collected for further purification. The pooled fractions were desalted on a SEPHADEX™ G-25 (medium) column equilibrated with 25 mM MES pH 6.0. The elution of the protein was monitored at 280 nm and fractions with high absorbance at 280 nm were chosen for the second chromatographic step.
The pooled fractions were applied to the 60 ml RESOURCE™ 15Q column equilibrated with 25 mM MES pH 6.0 and bound proteins were eluted with a linear 100-200 mM sodium chloride gradient for 1.5 column volumes followed by 1.5 column volumes of 300 mM sodium chloride, followed by 1.5 column volumes of 1 M sodium chloride. The elution of the protein was monitored at 280 nm and fractions with high absorbance at 280 nm were analysed on SDS-PAGE.
Fractions with high content of cellobiohydrolase I were pooled.
Example 34: Activity Measurement on Microcrystalline Cellulose of the Rasamsonia Emersonii PC1-147 Fusion Cellobiohydrolase I and the R. emersonii Cellobiohydrolase I PC1-378 Variant
The activity of the purified R. emersonii PC1-147 fusion cellobiohydrolase I and the R. emersonii cellobiohydrolase I PC1-378 variant (Example 33) were compared to the purified wild-type R. emersonii cellobiohydrolase I (Example 24) using washed microcrystalline cellulose as a substrate according to Example 25. Values are shown in relative activity where 100% was set as the activity of R. emersonii wild-type cellobiohydrolase I. The assay conditions were 24 hours incubation at pH 5, 50° C. and 1100 rpm.
The results as shown in FIG. 11 demonstrated that the R. emersonii PC1-147 fusion cellobiohydrolase I and the R. emersonii cellobiohydrolase I PC1-378 variant had an approximately 22% and 44% increase in activity toward microcrystalline cellulose, respectively, compared to the R. emersonii wild-type cellobiohydrolase I.
Example 35: Preparation, Expression, and Purification of the R. emersonii Cellobiohydrolase I PC1-496 Variant
The R. emersonii cellobiohydrolase I variant PC1-496 of the R. emersonii PC1-147 fusion cellobiohydrolase I (supra) was designed with deletions at positions S193*, N194*, and N195* (corresponding to deletions at positions 196, 197, and 198 of SEQ ID NO: 2), and then constructed and expressed using procedures similar to those described above. The variant PC1-496 coding sequence and corresponding amino acid sequence are shown in SEQ ID NOs: 77 and 78, respectively.
The fermentation broths were filtered through PES Bottle top filter with a 0.22 μm cut-off. Ammonium sulphate was added to the filtered fermentation broths to make a 1.8 M solution.
The cellobiohydrolases I were purified by HIC/affinity chromatography followed by IEX/affinity chromatography.
In the HIC/affinity chromatographic step, the fermentation broths were applied to a 200 ml Phenyl SEPHAROSE® 6 Fast Flow column (high sub) (GE Healthcare, Piscataway, N.J., USA) which had been pre-equilibrated with 1.8 M ammonium sulphate, 25 mM HEPES pH 7.0. After applying the sample, the column was washed with 2 CV 1.8 M ammonium sulphate followed by 1 CV 0.54 M ammonium sulphate. The bound proteins were batch eluted with 25 mM HEPES pH 7.0.
The elution of the protein was monitored at 280 nm. Fractions with high 280 nm absorbance were analyzed on SDS-PAGE using 12-well NUPAGE® 4-12% Bis-Tris gel (GE Healthcare, Piscataway, N.J., USA) for their cellobiohydrolase I content. Fractions with high content of this protein were pooled and collected for further purification. The pooled fractions were desalted on a SEPHADEX™ G-25 (medium) column (GE Healthcare, Piscataway, N.J., USA) equilibrated with 25 mM MES pH 6.0. The elution of the protein was monitored at 280 nm and fractions with high absorbance at 280 nm were chosen for the second chromatographic step.
The pooled fractions were applied to the 60 ml RESOURCE™ 15Q column (GE Healthcare, Piscataway, N.J., USA) equilibrated with 25 mM MES pH 6.0 and bound proteins were eluted with a linear 100-200 mM sodium chloride gradient for 1.5 CV followed by 1.5 CV 300 mM sodium chloride, followed by 1.5 CV 1 M sodium chloride. The elution of the protein was monitored at 280 nm and fractions with high absorbance at 280 nm were analyzed on SDS-PAGE.
Fractions with high content of cellobiohydrolase I were pooled.
Example 36: Activity Measurement on Microcrystalline Cellulose on Microcrystalline Cellulose of the Rasamsonia emersonii PC1-147 Fusion Cellobiohydrolase I and the R. emersonii Cellobiohydrolase I PC1-496 Variant
The activity of the purified R. emersonii cellobiohydrolase I PC1-496 variant (Example 35) was compared to purified R. emersonii PC1-147 fusion cellobiohydrolase I using washed microcrystalline cellulose (AVICEL® PH101; Sigma-Aldrich, St. Louis, Mo., USA) as a substrate.
The purified cellobiohydrolase variants were diluted in 50 mM sodium acetate, 2 mM CaCl 2 pH 5. The diluted cellobiohydrolase I variants were added to each well (microwell plate 96F 26960 Thermo scientific). Following washed AVICEL was added to each well and the microtiter plate was quickly transferred to a thermomixer (eppendorf) and incubated for 30 min at 1100 rpm and 25° C. The final concentration of cellobiohydrolase I variants in the reaction was 2.4 μM and the concentration of AVICEL was 24.5 g/l. The reaction was stopped by centrifugation at 3500 rpm for 3 min at 5° C. (Hereaus multifuge 3 S—R). 50 μl supernatants were transferred to PCR sample tubes (Thermoscientific 0.2 ml non-skirtet 96-well PCR plate AB0600). PAHBAH (4-hydroxy-benzhydrazid) (Sigma, H 9882) was dissolved in buffer (0.18 M K—Na-tartrate (Merck, 1.08087) and 0.5 M NaOH) to make a 15 mg/ml solution. 75 μl of the PAHBAH solution was added to the supernatants in the PCR sample tubes.
The PCR sample tubes were placed in a Peltier Thermal Cycler and incubated at 95° C. for 10 min and 20° C. for 5 min. After incubation 100 μl were transferred to a 96 well microtiter plate (microwell plate 96F 26960 Thermo scientific) and the absorbance was measured at 410 nm. For each run a standard was included. The standard used was cellobiose diluted in 50 mM sodium acetate, 2 mM CaCl 2 pH 5 to a concentration of 0.008, 0.016, 0.0312, 0.0625, 0.125, 0.25, 0.5 mM. In addition to the standard, a blank (without cellobiohydrolases) was included. For all the measurement, the blank measurement was subtracted. The absorbance data were normalized to cellobiose concentration using the standards.
The results as shown in FIG. 12 demonstrated that the cellobiohydrolase variant PC1-496 (comprising deletions at positions corresponding to 196, 197, and 198 of SEQ ID NO: 2) had an approximately 119% increase in activity toward microcrystalline cellulose compared to the wild-type cellobiohydrolase I at 25° C. and an increase of 54% compared with the R. emersonii PC1-147 fusion cellobiohydrolase I.
Example 37: Pretreated Corn Stover Hydrolysis Assay
Corn stover was pretreated at the U.S. Department of Energy National Renewable Energy Laboratory (NREL) using 1.4 wt % sulfuric acid at 165° C. and 107 psi for 8 minutes. The water-insoluble solids in the pretreated corn stover (PCS) contained 56.5% cellulose, 4.6% hemicellulose, and 28.4% lignin. Cellulose and hemicellulose were determined by a two-stage sulfuric acid hydrolysis with subsequent analysis of sugars by high performance liquid chromatography using NREL Standard Analytical Procedure #002. Lignin was determined gravimetrically after hydrolyzing the cellulose and hemicellulose fractions with sulfuric acid using NREL Standard Analytical Procedure #003.
Unmilled, unwashed PCS (whole slurry PCS) was prepared by adjusting the pH of the PCS to 5.0 by addition of 10 M NaOH with extensive mixing, and then autoclaving for 20 minutes at 120° C. The dry weight of the whole slurry PCS was 29%.
A 96-well plate was generated by machining a teflon plate of depth ¼ inch with 96, cone-shaped wells, diameter ¼ inch at the upper surface and diameter ⅛ inch at the lower surface. The center of each well was at an equivalent position to the center of a corresponding well in a standard 96-well microtiter plate, approximately 23/64 inch on center. The resulting volume of each well was approximately 135 μl. This 96-well aluminum plate is hereinafter referred to as the “fill plate”. The pH-adjusted corn stover was used to fill the holes in the fill plate by applying a suitable volume of the corn stover to the upper surface of the plate, then using a spatula to spread the material over the surface and into the holes. Holes were deemed sufficiently full when corn stover was extruded through the hole in the bottom surface, forming noodle-like tubes. A MULTISCREEN® Column Loader Scraper (Millipore) held perpendicular to the fill plate surface was used to scrape excess corn stover from the top and bottom surfaces of the fill plate, leaving the surfaces of the corn stover in each well flush with the surfaces of the fill plate. The fill plate was then placed on the top of a 2.2 ml deep well plate (Axygen, Union City, Calif., USA) with the top surface adjacent to the open end of the well plate (e.g. the top of the well plate), and the wells aligned with the corn stover-filled holes in the fill plate. The fill plate was secured in this position, and the assembly centrifuged at 2500 rpm (1350× g) for 5 minutes in a Sorvall Legend RT+(Thermo Scientific, Waltham, Mass., USA). Following centrifugation, the corn stover had been transferred to the deep well plate. A 3 mm glass bead (Fisher Scientific, Waltham, Mass., USA) was placed in each well for mixing.
The hydrolysis of PCS was conducted in a total reaction volume of 0.2 ml. The hydrolysis was performed with 50 mg of insoluble PCS solids containing 50 mM sodium acetate pH 5.0 buffer containing 1 mM manganese sulfate and various protein loadings of various enzyme compositions (expressed as mg protein per gram of cellulose). Enzyme compositions were prepared and then added simultaneously to all wells in a volume ranging from 20 μl to 50 μl, for a final volume of 0.2-0.50 ml in each reaction. The plate was then sealed using an ALPS-300™ plate heat sealer (Abgene, Epsom, United Kingdom), mixed thoroughly, and incubated at a specific temperature for 72 hours.
Following hydrolysis, samples were filtered using a 0.45 μm MULTISCREEN® 96-well filter plate (Millipore, Bedford, Mass., USA) and filtrates analyzed for sugar content as described below. When not used immediately, filtered aliquots were frozen at −20° C. The sugar concentrations of samples diluted in 0.005 M H 2 SO 4 were measured using a 4.6×250 mm AMINEX® HPX-87H column (Bio-Rad Laboratories, Inc., Hercules, Calif., USA) by elution with 0.05% w/w benzoic acid-0.005 M H 2 SO 4 at 65° C. at a flow rate of 0.6 ml per minute, and quantitation by integration of the glucose, cellobiose, and xylose signals from refractive index detection (CHEMSTATION®, AGILENT® 1100 HPLC, Agilent Technologies, Santa Clara, Calif., USA) calibrated by pure sugar samples. The resultant glucose and cellobiose equivalents were used to calculate the percentage of cellulose conversion for each reaction.
Glucose and cellobiose were measured individually. Measured sugar concentrations were adjusted for the appropriate dilution factor. The net concentrations of enzymatically-produced sugars from unwashed PCS were determined by adjusting the measured sugar concentrations for corresponding background sugar concentrations in unwashed PCS at zero time point. All HPLC data processing was performed using MICROSOFT EXCEL™ software (Microsoft, Richland, Wash., USA).
The degree of glucose conversion to glucose was calculated using the following equation: % cellulose conversion=(glucose concentration)/(glucose concentration in a limit digest)×100. In order to calculate % glucose conversion, a 100% conversion point was set based on a cellulase control (100 mg of T. reesei cellulase supplemented with Thermoascus aurantiacus GH61A polypeptide, Aspergillus fumigatus GH10 xylanase (xyn3), and Talaromyces emersonii beta-xylosidase per gram cellulose). Quadruplicate data points were averaged and standard deviation was calculated.
Example 38: Preparation of an Enzyme Composition #3 without Cellobiohydrolase I
The Talaromyces leycettanus GH6 cellobiohydrolase II (GENESEQP:AZY49446) was prepared recombinantly in Aspergillus oryzae as described in WO 2012/103288. The filtered broth of the Talaromyces leycettanus GH6 cellobiohydrolase II was concentrated and buffer exchanged into 20 mM Tris pH 8.0 using a 400 ml SEPHADEX™ G-25 column (GE Healthcare, United Kingdom). The fractions were pooled, and 3 M ammonia sulfate, 20 mM Tris pH 8.0 was added to the desalted protein to a final concentration of 1.2 M ammonia sulfate, 20 mM Tris pH 8.0. The protein was loaded onto a Phenyl Sepharose™ 6 Fast Flow column (high sub) (GE Healthcare, Piscataway, N.J., USA) equilibrated in 20 mM Tris pH 8.0 with 1.2 M ammonium sulfate, and bound proteins were eluted with 20 mM Tris pH 8.0 with no ammonium sulfate. Fractions were analyzed by 8-16% Tris-HCl SDS-PAGE gels (Bio-Rad, Hercules, Calif., USA), and pooled. The pooled protein was buffer exchanged into 20 mM MES pH 6.0 using a Vivaflow 200 with 10 kDa molecular weight cut-off tangential flow membrane (Sartorius, Bohemia, N.Y., USA).
The Trichoderma reesei GH5 endoglucanase II (GENESEQP:AZI04858) was prepared recombinantly according to WO 2011/057140 using Aspergillus oryzae as a host. The filtered broth of the T. reesei endoglucanase II was desalted and buffer-exchanged into 20 mM Tris pH 8.0 using a tangential flow concentrator (Pall Filtron, Northborough, Mass., USA) equipped with a 10 kDa polyethersulfone membrane (Pall Filtron, Northborough, Mass., USA).
Thermoascus aurantiacus CGMCC 0583 GH61A polypeptide having cellulolytic enhancing activity (GENESEQP:AEC05922) was recombinantly prepared according to WO 2005/074656 using Aspergillus oryzae JaL250 as a host. The broth was filtered using a 0.22 μm EXPRESS™ Plus Membrane (Millipore, Bedford, Mass., USA).
The Aspergillus fumigatus GH10 xylanase (xyn3) (GENESEQP:AZI04884) was prepared recombinantly according to WO 2006/078256 using Aspergillus oryzae BECh2 (WO 2000/39322) as a host. The filtered broth of the A. fumigatus xylanase was desalted and buffer-exchanged into 50 mM sodium acetate pH 5.0 using a HIPREP® 26/10 Desalting Column (GE Healthcare, Piscataway, N.J., USA).
The Aspergillus fumigatus Cel3A beta-glucosidase 4M mutant (GENESEQP:AZU67153) was recombinantly prepared according to WO 2012/044915. The filtered broth of Aspergillus fumigatus Cel3A beta-glucosidase 4M was concentrated and buffer exchanged using a tangential flow concentrator (Pall Filtron, Northborough, Mass., USA) equipped with a 10 kDa polyethersulfone membrane (Pall Filtron, Northborough, Mass., USA) with 50 mM sodium acetate pH 5.0 containing 100 mM sodium chloride.
The Talaromyces emersonii CBS 393.64 beta-xylosidase (GENESEQP:AZI04896) was prepared recombinantly according to Rasmussen et al., 2006 , Biotechnology and Bioengineering 94: 869-876 using Aspergillus oryzae JaL355 as a host (WO 2003/070956). The filtered broth was concentrated and desalted with 50 mM sodium acetate pH 5.0 using a tangential flow concentrator equipped with a 10 kDa polyethersulfone membrane (Pall Filtron, Northborough, Mass., USA).
The protein concentration for each of the monocomponents described above was determined using a Microplate BCA™ Protein Assay Kit (Thermo Fischer Scientific, Waltham, Mass., USA) in which bovine serum albumin was used as a protein standard. An enzyme composition was prepared composed of each monocomponent as follows: 39.7% Talaromyces leycettanus GH6 cellobiohydrolase II, 15.9% Trichoderma reesei GH5 endoglucanase II, 23.8% Thermoascus aurantiacus GH61A polypeptide, 7.9% Aspergillus fumigatus GH10 xylanase, 7.9% Aspergillus fumigatus beta-glucosidase, and 4.8% Talaromyces emersonii beta-xylosidase. The enzyme composition is designated herein as “cellulolytic enzyme composition #3 without cellobiohydrolase I”.
Example 39: Comparison of the Effect of the Rasamsonia emersonii PC1-147 Fusion Cellobiohydrolase I and the R. emersonii Cellobiohydrolase I PC1-496 Variant on the Hydrolysis of Unwashed PCS by a Cellulase Enzyme Composition
The R. emersonii cellobiohydrolase I PC1-496 variant (Example 35) was added to the cellulolytic enzyme composition #3 without cellobiohydrolase I (Example 39) at 35° C., 50° C., and 60° C. using unwashed PCS as a substrate, and compared against the R. emersonii PC1-147 fusion cellobiohydrolase I added to the cellulolytic enzyme composition #3 without cellobiohydrolase I. Each cellobiohydrolase I was added individually at 3.33 mg enzyme protein per g cellulose to 5.67 mg enzyme protein of the cellulase enzyme composition #3 without cellobiohydrolase I per g cellulose.
The assay was performed as described supra. The reactions with unwashed PCS (20% total solids) were conducted for 72 hours at 35° C., 50° C., and 60° C. in 50 mM sodium acetate pH 5.0 buffer containing 1 mM manganese sulfate. All reactions were performed in quadruplicate and shaking at 200 rpm throughout the hydrolysis.
The results shown in FIG. 13 demonstrated that the cellulase enzyme composition containing the R. emersonii cellobiohydrolase I PC1-496 variant had significantly higher cellulose conversion than the cellulase enzyme composition that included R. emersonii PC1-147 fusion cellobiohydrolase I at 35° C.
Example 40: Preparation, Expression, and Purification of the Trichoderma reesei Cellobiohydrolase I Variants TC1-213 and TC1-216
The Trichoderma reesei cellobiohydrolase I variant TC1-213 of the Trichoderma reesei wild-type GH7 cellobiohydrolase I of SEQ ID NO: 2 was designed with deletions at positions N197* and N198*, and then constructed and expressed using procedures similar to those described above. The variant TC1-213 coding sequence and corresponding amino acid sequence are shown in SEQ ID NOs: 79 and 80 respectively.
The Trichoderma reesei cellobiohydrolase I variant TC1-216 of the Trichoderma reesei wild-type GH7 cellobiohydrolase I of SEQ ID NO: 2 was designed with deletions at positions S195* and S196*, and then constructed and expressed using procedures similar to those described above. The variant TC1-216 coding sequence and corresponding amino acid sequence are shown in SEQ ID NOs: 81 and 82, respectively.
Two synthetic primers for each site-directed mutagenesis were designed as below using the SOE primer design tool. Primers F-N197* N198* and R-N197* N198* were used to generate the deletions of variant TC1-213. Primers F-S195* S196* and R-S195* S196* were used to generate the deletions of variant TC1-216.
Primer F-N197* N198*:
(SEQ ID NO: 83)
5′-AAGGC TGGGA ACCCT CGTCG GCCAA CACCG GCATT
GGAGG-3′
Primer R-N197* N198*:
(SEQ ID NO: 84)
5′-CGACG AGGGT TCCCA GCCTT CGACG TTTGC C-3′
Primer F-S195* S196*:
(SEQ ID NO: 85)
5′-ACGTC GAAGG CTGGG AACCC AACAA CGCCA ACACC
GGCAT TG-3′
Primer R-S195* S196*:
(SEQ ID NO: 86)
5′-GGGTT CCCAG CCTTC GACGT TTGCC TGGCC-3′
The variants were constructed using the plasmid pKHJN0036 (Example 3) which contains the codon optimized gene encoding the Trichoderma reesei cellobiohydrolase I, and then expressed and purified using procedures as described above in Examples 2, 5 and 7.
Example 41: Comparison of the Effect of Trichoderma reesei Cellobiohydrolase I TC1-213 Variant Polypeptides (TC1-213 and TC1-216) Against Trichoderma reesei Cellobiohydrolase I Wild-Type on the Hydrolysis of Unwashed PCS by a Cellulase Enzyme Composition
The Trichoderma reesei variant polypeptides TC1-213 and TC1-216 from Example 40 (corresponding to a deletion of N197+N198 and S195+S196 respectively) were added to the cellulolytic enzyme composition without cellobiohydrolase I (Example 38) at 35° C. using unwashed PCS as a substrate, and compared against the Trichoderma reesei cellobiohydrolase I wild-type polypeptide. Each cellobiohydrolase I was added individually at 2, 3, and 4 mg enzyme protein per g cellulose to 5.108 mg enzyme protein of the cellulase enzyme composition without cellobiohydrolase I per g cellulose.
The assay was performed as described in Example 37. The reactions with unwashed PCS (20% total solids) were conducted for 72 hours at 35° C. in 80 mM sodium acetate pH 5.0 buffer containing 1 mM manganese sulfate. All reactions were performed in quadruplicate and shaking at 200 rpm throughout the hydrolysis.
The results shown in FIG. 14 demonstrated that the cellulase enzyme composition containing the variant polypeptide TC1-213 had significantly higher cellulose conversion at 35° C. compared to the cellulase enzyme composition that included the Trichoderma reesei cellobiohydrolase I wild-type at 2 mg enzyme protein per g cellulose only. In addition, the cellulase enzyme composition containing the variant polypeptide TC1-216 had significantly higher cellulose conversion at 35° C. compared to the cellulase enzyme composition that included the Trichoderma reesei cellobiohydrolase I wild-type at all protein loadings.
Example 42: Source of DNA Sequence Information for Aspergillus fumigatus Cellobiohydrolase I
The genomic DNA sequence and deduced amino acid sequence of the Aspergillus fumigatus Af293 GH7 cellobiohydrolase I gene is shown in SEQ ID NO: 87 and SEQ ID NO: 8, respectively. Genomic sequence information was generated by The Institute for Genomic Research, Rockville, Md. 20850, USA and published by Nierman, W. C. et al., 2005 , Nature 438 (7071): 1151-1156. The amino acid sequence of the full-length cellobiohydrolase I is publicly available from the National Center for Biotechnology Information (NCBI) and annotated as GenBank: EAL89006.1 The cDNA sequence and deduced amino acid sequence of the Aspergillus fumigatus cellobiohydrolase I gene is shown in SEQ ID NO: 88 and SEQ ID NO: 8, respectively.
Based on the publicly available amino acid sequence, a codon-optimized synthetic gene encoding the full-length cellobiohydrolase I was generated for Aspergillus oryzae expression based on the algorithm developed by Gustafsson et al., 2004 , Trends in Biotechnology 22 (7): 346-353. The codon-optimized coding sequence (SEQ ID NO: 89) was synthesized by the GENEART® Gene Synthesis service (Life Technologies Corp., San Diego. Calif., USA) with a 5′ Bam HI restriction site, a 3′ Hind III restriction site, and a Kozac consensus sequence (CACC) situated between the start codon and the Bam HI restriction site.
Example 43: Construction of an Aspergillus oryzae Expression Vector Containing an Aspergillus fumigatus DNA Sequence Encoding Cellobiohydrolase I
The ampicillin-resistant E. coli cloning vector provided by GENEART® Gene Synthesis encoding the A. fumigatus cellobiohydrolase I (Example 14) was digested with Barn HI and Hind III (New England Biolabs, MA, USA) according to manufacturer's instructions. The reaction products were isolated by 1.0% agarose gel electrophoresis using TAE buffer where a 1606 bp product band was excised from the gel and purified using a MinElute Gel Extraction Kit (QIAGEN Inc., Valencia, Calif., USA).
The purified 1606 bp fragment encoding the A. fumigatus cellobiohydrolase I was cloned into pDau109 (WO 2005/042735) digested with Bam HI and Hind III using T4 DNA ligase (New England Biolabs, MA, USA). The Bam HI-Hind III digested pDau109 and the Barn HI/Hind III fragment containing the A. fumigatus cellobiohydrolase I were mixed in a molar ratio of 1:3 (i.e., equal volumes of gel purified products) and ligated with 50 units of T4 DNA ligase in 1× T4 DNA ligase buffer with 1 mM ATP and incubated at 22° C. for 10 minutes.
Cloning of the A. fumigatus cellobiohydrolase I gene into the Bam HI-Hind III digested pDau109 will result in transcription of the A. fumigatus cellobiohydrolase I gene under the control of a NA2-tpi double promoter. The NA2-tpi promoter is a modified promoter from the gene encoding the Aspergillus niger neutral alpha-amylase in which the untranslated leader has been replaced by an untranslated leader from the gene encoding the Aspergillus nidulans triose phosphate isomerase.
The ligation mixture was transformed into ONE SHOT® TOP10F′ Chemically Competent E. coli cells according to the manufacturer's protocol and spread onto LB plates supplemented with 0.1 mg of ampicillin per ml. After incubation at 37° C. overnight, colonies were observed growing under selection on the LB ampicillin plates.
Insertion of the A. fumigatus cellobiohydrolase I gene into pDau109 was verified by DNA sequencing. The isolated plasmids were sequenced using an Applied Biosystems 3730xl DNA Analyzer with vector primers and A. fumigatus cellobiohydrolase I gene specific primers, shown below, in order to determine a representative plasmid that was free of PCR errors and contained the desired insert.
Primer F-pDau109
(SEQ ID NO: 90)
5′-CCCTT GTCGA TGCGA TGTAT C-3′
Primer R-pDau109
(SEQ ID NO: 91)
5′-ATCCT CAATT CCGTC GGTCG A-3′
Primer F-pE596
(SEQ ID NO: 92)
5′-GTGAT ACACC CGGAC AGGTG ATGTG-3′
Primer R-pE596
(SEQ ID NO: 93)
5′-CCATA TCGAT CCGAC GAGTA GGTTC-3′
An E. coli transformant containing the A. fumigatus cellobiohydrolase I plasmid construct was cultivated in LB medium supplemented with 0.1 mg of ampicillin per ml and plasmid DNA was isolated using a QIAPREP® Spin Miniprep Kit. The plasmid was designated pE596 and the corresponding polypeptide was designated as AC1-596.
Example 44: Site-Directed Mutagenesis of the Aspergillus fumigatus Cellobiohydrolase I (AC1-865)
Plasmid pE596 (Example 43) was used to generate the A. fumigatus cellobiohydrolase I AC1-865 variant (SEQ ID NO: 94 for the mutant DNA sequence and SEQ ID NO: 95 for the variant), where three codons TCG AAC GAT were deleted (S196 N197 D198) to give S196* N197* D198* (corresponding to deletions at positions 196, 197, and 198 of SEQ ID NO: 2).
Two synthetic primers for site-directed mutagenesis were designed using a SOE primer design tool. Site-directed mutagenesis of the synthetic gene encoding the wild-type A. fumigatus cellobiohydrolase I was facilitated by PCR amplifications of pE596 using the primers and procedure described below:
Primer F-S196* N197* D198*:
(SEQ ID NO: 96)
5′-TCGAG GGTTG GCAGC CTTCG GCCAA CGCAG GTACC GGCAA
C-3′
Primer R-S196* N197* D198*:
(SEQ ID NO: 97)
5′-CGAAG GCTGC CAACC CTCGA CGTTG GCCTG-3′
The mutations were introduced by PCR using a PHUSION® High-Fidelity PCR Kit (New England Biolabs, MA, USA). The PCR solution was composed of 10 μl of 5× HF buffer (New England Biolabs, MA, USA), 4 μl of dNTPs (2.5 mM), 0.5 μl of PHUSION® DNA polymerase (0.2 units/μl) (New England Biolabs, MA, USA), 0.25 μl of primer F-S196* N197* D198* (100 μM), 0.25 μl of primer R-S196* N197* D198* (100 μM), 5 μl of template DNA (pE596, 1 ng/μl), and 30 μl of deionized water in a total volume of 50 μl. The PCR was performed using an Applied Biosystems® Veriti® 96 well thermal cycler programmed for 1 cycle at 98° C. for 30 seconds; and 19 cycles each at 98° C. for 30 seconds, 55° C. for 1 minute, and 72° C. for 7 minutes. The PCR solution was then held at 8° C. until removed from the PCR machine.
Following the PCR, 10 units of Dpn I were added directly to the PCR solution and incubated at 37° C. for 1 hour. Then 1 μl of the Dpn I treated PCR solution was transformed into ONE SHOT® TOP10F′ Chemically Competent E. coli cells according to the manufacturer's protocol and spread onto LB plates supplemented with 0.15 mg of ampicillin per ml. After incubation at 37° C. overnight, transformants were observed growing under selection on the LB ampicillin plates. Four transformants were cultivated in LB medium supplemented with 0.10 mg of ampicillin per ml and plasmids were isolated using a QIAPREP® Spin Miniprep Kit (QIAGEN Inc., Valencia, Calif., USA).
The isolated plasmids were sequenced using an Applied Biosystems 3730xl DNA Analyzer (Applied Biosystems, Foster City, Calif., USA) with primers F-pDau109 (SEQ ID NO: 30), R-pDau109 (SEQ ID NO: 310), F-pE596 (SEQ ID NO: 92) and R-pE596 (SEQ ID NO: 93), in order to determine a representative plasmid that was free of PCR errors and contained the desired mutations.
Primer F-pDau109:
(SEQ ID NO: 30)
5′-CCCTT GTCGA TGCGA TGTAT C-3′
Primer R-pDau109:
(SEQ ID NO: 31)
5′-ATCCT CAATT CCGTC GGTCG A-3′
Primer F-pE596:
(SEQ ID NO: 92)
5′-GTGAT ACACC CGGAC AGGTG ATGTG-3′
Primer R-pE596:
(SEQ ID NO: 93)
5′-CCATA TCGAT CCGAC GAGTA GGTTC-3′
One plasmid clone free of PCR errors and containing the deletion of codons TCG AAC GAT (S196* N197* D198*) was chosen and designated plasmid pE865 and the corresponding polypeptide was designated as AC1-865.
Generating the Aspergillus oryzae strain expressing the AC1-865 variant and the AC1-596 wild type were done using the same method as described in Example 5. Based on the level of hydrolysis of the microcrystalline cellulose one transformant expressing the A. fumigatus cellobiohydrolase I variant AC1-865 was selected and designated A. oryzae AC1-865 and one transformant expressing the wild type A. fumigatus cellobiohydrolase I was selected and designated A. oryzae AC1-596.
Purification of the wild-type Aspergillus fumigatus cellobiohydrolase I AC1-596 and the variant AC1-865 were done essentially as described in Example 7.
Example 45: Activity Measurement on Microcrystalline Cellulose of the Variant AC1-865 and the Wild-Type Aspergillus fumigatus Cellobiohydrolase I
The activity of the purified variant polypeptide AC1-865 was compared to the purified wild-type A. fumigatus cellobiohydrolase I AC1-596 using washed microcrystalline cellulose (AVICEL® PH101; Sigma-Aldrich, St. Louis, Mo., USA) as a substrate (see PCT/US2014/022068).
The purified cellobiohydrolases were diluted in 50 mM sodium acetate, 2 mM CaCl 2 pH 5. The diluted cellobiohydrolases and β-glucosidase were added to each well (microwell plate 96F 26960 Thermo scientific). Washed AVICEL then was added to each well and the microtiter plate was quickly transferred to a thermomixer (eppendorf) and incubated for 24 hours at 1100 rpm and 35° C. or 55° C. The final concentration of the cellobiohydrolases in the reaction was 3 μM and the concentration of AVICEL was 80 g/l. The reaction was stopped by centrifugation at 3500 rpm for 3 min at 5° C. (Hereaus multifuge 3 S-R). The supernatants are diluted 40 times and 50 μL of diluted supernatants were transferred to PCR sample tubes (Thermoscientific 0.2 ml non-skirtet 96-well PCR plate AB0600). PAHBAH (4-hydroxy-benzhydrazid) (Sigma, H 9882) was dissolved in buffer (0.18 M K—Na-tartrate (Merck, 1.08087) and 0.5 M NaOH) to make a 15 mg/ml solution. Seventy-five μL of the PAHBAH solution was added to the supernatants in the PCR samples tubes.
The PCR sample tubes were placed in a Peltier Thermal Cycler and incubated at 95° C. for 10 min and 20° C. for 5 min. After incubation 100 μl were transferred to a 96 well microtiter plate (microwell plate 96F 26960 Thermo scientific) and the absorbance was measured at 410 nm. For each run a standard was included. The standard used was glucose diluted in 50 mM sodium acetate, 2 mM CaCl2 pH 5 to a concentration of 0.008, 0.016, 0.0312, 0.0625, 0.125, 0.25 and 0.5 mM. In addition to the standard, a blank (without cellobiohydrolase) for each run was included. For all the measurement, the blank measurement was subtracted. The absorbance data were normalized to glucose concentration using the standards.
The results as shown in FIG. 15 demonstrated that at 35° C., the variant AC1-865 (with a deletion of S196 N197 and D198) had an approximately 23% increase toward microcrystalline cellulose compared to the wild-type cellobiohydrolase I.
The invention described and claimed herein is not to be limited in scope by the specific aspects herein disclosed, since these aspects are intended as illustrations of several aspects of the invention. Any equivalent aspects are intended to be within the scope of this invention. Indeed, various modifications of the invention in addition to those shown and described herein will become apparent to those skilled in the art from the foregoing description. Such modifications are also intended to fall within the scope of the appended claims. In the case of conflict, the present disclosure including definitions will control.
1.PublishNumber: US-2017292136-A1
2.Date Publish: 20171012
3.Inventor: WESTH PETER
BORCH KIM
Soerensen Trine
WINDAHL MICHAEL
MCBRAYER BRETT
4.Inventor Harmonized: WESTH PETER(DK)
BORCH KIM(DK)
Soerensen Trine(DK)
WINDAHL MICHAEL(DK)
MCBRAYER BRETT(US)
5.Country: US
6.Claims:
(en)The present invention relates to cellobiohydrolase variants. The present invention also relates to polynucleotides encoding the variants; nucleic acid constructs, vectors, and host cells comprising the polynucleotides; and methods of using the variants.
7.Description:
(en)CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority from U.S. Provisional Patent Application Ser. No. 62/047,296 filed Sep. 8, 2014. The content of this application is fully incorporated herein by reference.
REFERENCE TO A SEQUENCE LISTING
This application contains a Sequence Listing in computer readable form, which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to cellobiohydrolase variants, polynucleotides encoding the variants, and methods of producing and using the variants.
Description of the Related Art
Cellulose is a polymer of the simple sugar glucose covalently linked by beta-1,4-bonds. Many microorganisms produce enzymes that hydrolyze beta-linked glucans. These enzymes include endoglucanases, cellobiohydrolases, and beta-glucosidases. Endoglucanases digest the cellulose polymer at random locations, opening it to attack by cellobiohydrolases. Cellobiohydrolases sequentially release molecules of cellobiose from the ends of the cellulose polymer. Cellobiose is a water-soluble beta-1,4-linked dimer of glucose. Beta-glucosidases hydrolyze cellobiose to glucose.
The conversion of lignocellulosic feedstocks into ethanol has the advantages of the ready availability of large amounts of feedstock, the desirability of avoiding burning or land filling the materials, and the cleanliness of the ethanol fuel. Wood, agricultural residues, herbaceous crops, and municipal solid wastes have been considered as feedstocks for ethanol production. These materials primarily consist of cellulose, hemicellulose, and lignin. Once the lignocellulose is converted to fermentable sugars, e.g., glucose, the fermentable sugars can easily be fermented by yeast into ethanol.
WO 2011/050037 discloses Thielavia terrestris cellobiohydrolase variants with improved thermostability. WO 2011/050037 discloses Aspergillus fumigatus cellobiohydrolase variants with improved thermostability. WO 2005/028636 discloses variants of Hypocrea jecorina Cel7A cellobiohydrolase I. WO 2005/001065 discloses variants of Humicola grisea Cel7A cellobiohydrolase I, Hypocrea jecorina cellobiohydrolase I, and Scytalidium thermophilium cellobiohydrolase I. WO 2004/016760 discloses variants of Hypocrea jecorina Cel7A cellobiohydrolase I. U.S. Pat. No. 7,375,197 discloses variants of Trichoderma reesei cellobiohydrolase I.
Hybrid polypeptides comprising a cellobiohydrolase catalytic domain and a carbohydrate binding module are described in e.g., WO 2010/060056, WO 2013/091577, and WO 2014/138672.
There is a need in the art for cellobiohydrolase variants with improved properties to increase the efficiency of the saccharification of lignocellulosic feedstocks.
The present invention provides cellobiohydrolase variants with increased specific performance, polynucleotides encoding the variants, and methods of producing and using the variants.
SUMMARY OF THE INVENTION
The present invention relates to cellobiohydrolase variants, comprising deletions at two or more consecutive positions of the B2-loop, wherein the variants have cellobiohydrolase activity.
The present also invention relates to cellobiohydrolase variants, comprising a deletion at one or more positions corresponding to positions 195, 196, 197, and 198 of SEQ ID NO: 2, and wherein the variants have cellobiohydrolase activity.
The present invention also relates to isolated polynucleotides encoding the variants; nucleic acid constructs, vectors, and host cells comprising the polynucleotides; and methods of producing the variants.
The present invention also relates to processes for degrading a cellulosic material, comprising: treating the cellulosic material with an enzyme composition in the presence of a cellobiohydrolase variant of the present invention. In one aspect, the processes further comprise recovering the degraded cellulosic material.
The present invention also relates to processes of producing a fermentation product, comprising: (a) saccharifying a cellulosic material with an enzyme composition in the presence of a cellobiohydrolase variant of the present invention; (b) fermenting the saccharified cellulosic material with one or more (e.g., several) fermenting microorganisms to produce the fermentation product; and (c) recovering the fermentation product from the fermentation.
The present invention also relates to processes of fermenting a cellulosic material, comprising: fermenting the cellulosic material with one or more (e.g., several) fermenting microorganisms, wherein the cellulosic material is saccharified with an enzyme composition in the presence of a cellobiohydrolase variant of the present invention. In one aspect, the fermenting of the cellulosic material produces a fermentation product. In another aspect, the processes further comprise recovering the fermentation product from the fermentation.
BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 shows saccharide production from microcrystalline cellulose by the Trichoderma reesei wild-type cellobiohydrolase I and the cellobiohydrolase I M6 variant thereof after 5 hours at pH 5 and 25° C. The results were corrected for background sugars determined in a control sample.
FIG. 2 shows the effect of T. reesei cellobiohydrolase I M6 variant and T. reesei wild-type cellobiohydrolase I on hydrolysis of milled unwashed PCS by a cellulolytic enzyme composition at 24 hours.
FIG. 3 shows the effect of Trichoderma reesei cellobiohydrolase I M6 variant and Trichoderma reesei wild-type cellobiohydrolase I on hydrolysis of milled unwashed pretreated corn stover (PCS) by a cellulolytic enzyme composition at 48 hours.
FIG. 4 shows the effect of T. reesei cellobiohydrolase I M6 variant and T. reesei wild-type cellobiohydrolase I on hydrolysis of milled unwashed PCS by a cellulolytic enzyme composition at 72 hours.
FIG. 5 shows hydrolysis of microcrystalline cellulose by the T. reesei wild-type cellobiohydrolase I and the T. reesei cellobiohydrolase I A199*, N198A, N200G, and N200W variants. Values are shown in mM released cellobiose after 1 hour at pH 5, at 25° C. and at 1100 rpm.
FIG. 6 shows hydrolysis of microcrystalline cellulose by the Rasamsonia emersonii wild-type cellobiohydrolase I and R. emersonii cellobiohydrolase I PC1-146 variant. Values are shown in mM released cellobiose after 1 hour at pH 5, at 50° C. and at 1100 rpm.
FIG. 7 shows a comparison of the effect of the R. emersonii cellobiohydrolase I variant and R. emersonii wild-type cellobiohydrolase I on the hydrolysis of unwashed PCS (8% total solids) by a cellulase enzyme composition.
FIG. 8 shows a comparison of the effect of the R. emersonii cellobiohydrolase I PC1-146 variant and R. emersonii wild-type cellobiohydrolase I on the hydrolysis of unwashed PCS (20% total solids) by a cellulase enzyme composition.
FIG. 9 shows a comparison of the R. emersonii cellobiohydrolase I PC1-146 variant with the R. emersonii wild-type cellobiohydrolase I during hydrolysis.
FIG. 10 shows a comparison of the R. emersonii cellobiohydrolase I PC1-146 variant with the Rasamsonia emersonii wild-type cellobiohydrolase I during simultaneous saccharification and fermentation (SSF).
FIG. 11 shows a comparison of the hydrolysis of microcrystalline cellulose by the R. emersonii wild-type cellobiohydrolase I, R. emersonii PC1-147 fusion cellobiohydrolase I, and R. emersonii cellobiohydrolase I PC1-378 variant.
FIG. 12 shows a comparison of the hydrolysis of microcrystalline cellulose by the R. emersonii wild-type cellobiohydrolase I, R. emersonii PC1-147 fusion cellobiohydrolase I, and R. emersonii cellobiohydrolase I PC1-496 variant after 30 min at pH 5 and 25° C.
FIG. 13 shows a comparison of percent cellulose conversion of pretreated corn stover at 35° C., 50° C., and 60° C. by enzyme compositions comprising the R. emersonii PC1-147 fusion cellobiohydrolase I and the R. emersonii cellobiohydrolase I PC1-496 variant.
FIG. 14 shows a comparison of percent cellulose conversion of pretreated corn stover at 35° C. by enzyme compositions comprising the T. reesei cellobiohydrolase I variants TC1-213 and TC1-216 to those comprising the wild-type T. reesei cellobiohydrolase I.
FIG. 15 shows a comparison of the hydrolysis of microcrystalline cellulose by the Aspergillus fumigatus wild-type cellobiohydrolase I, and the Aspergillus fumigatus cellobiohydrolase I AC1-865 variant after 24 hours at 35° C.
DEFINITIONS
Acetylxylan esterase: The term “acetylxylan esterase” means a carboxylesterase (EC 3.1.1.72) that catalyzes the hydrolysis of acetyl groups from polymeric xylan, acetylated xylose, acetylated glucose, alpha-napthyl acetate, and p-nitrophenyl acetate. For purposes of the present invention, acetylxylan esterase activity is determined using 0.5 mM p-nitrophenylacetate as substrate in 50 mM sodium acetate pH 5.0 containing 0.01% TWEEN™ 20 (polyoxyethylene sorbitan monolaurate). One unit of acetylxylan esterase is defined as the amount of enzyme capable of releasing 1 μmole of p-nitrophenolate anion per minute at pH 5, 25° C.
Allelic variant: The term “allelic variant” means any of two or more alternative forms of a gene occupying the same chromosomal locus. Allelic variation arises naturally through mutation, and may result in polymorphism within populations. Gene mutations can be silent (no change in the encoded polypeptide) or may encode polypeptides having altered amino acid sequences. An allelic variant of a polypeptide is a polypeptide encoded by an allelic variant of a gene.
Alpha-L-arabinofuranosidase: The term “alpha-L-arabinofuranosidase” means an alpha-L-arabinofuranoside arabinofuranohydrolase (EC 3.2.1.55) that catalyzes the hydrolysis of terminal non-reducing alpha-L-arabinofuranoside residues in alpha-L-arabinosides. The enzyme acts on alpha-L-arabinofuranosides, alpha-L-arabinans containing (1,3)- and/or (1,5)-linkages, arabinoxylans, and arabinogalactans. Alpha-L-arabinofuranosidase is also known as arabinosidase, alpha-arabinosidase, alpha-L-arabinosidase, alpha-arabinofuranosidase, polysaccharide alpha-L-arabinofuranosidase, alpha-L-arabinofuranoside hydrolase, L-arabinosidase, or alpha-L-arabinanase. For purposes of the present invention, alpha-L-arabinofuranosidase activity is determined using 5 mg of medium viscosity wheat arabinoxylan (Megazyme International Ireland, Ltd., Bray, Co. Wicklow, Ireland) per ml of 100 mM sodium acetate pH 5 in a total volume of 200 μl for 30 minutes at 40° C. followed by arabinose analysis by AMINEX® HPX-87H column chromatography (Bio-Rad Laboratories, Inc., Hercules, Calif., USA).
Alpha-glucuronidase: The term “alpha-glucuronidase” means an alpha-D-glucosiduronate glucuronohydrolase (EC 3.2.1.139) that catalyzes the hydrolysis of an alpha-D-glucuronoside to D-glucuronate and an alcohol. For purposes of the present invention, alpha-glucuronidase activity is determined according to de Vries, 1998 , J. Bacteriol. 180: 243-249. One unit of alpha-glucuronidase equals the amount of enzyme capable of releasing 1 μmole of glucuronic or 4-O-methylglucuronic acid per minute at pH 5, 40° C.
B2-loop: The term “B2-loop” means the amino acids corresponding to P194 to T201 of the Trichoderma reesei Cel7A cellobiohydrolase of SEQ ID NO: 2, as described in Payne et al., Chem. Rev. 115: 11308-1448.
Beta-glucosidase: The term “beta-glucosidase” means a beta-D-glucoside glucohydrolase (E.C. 3.2.1.21) that catalyzes the hydrolysis of terminal non-reducing beta-D-glucose residues with the release of beta-D-glucose. For purposes of the present invention, beta-glucosidase activity is determined using p-nitrophenyl-beta-D-glucopyranoside as substrate according to the procedure of Venturi et al., 2002 , J. Basic Microbiol. 42: 55-66. One unit of beta-glucosidase is defined as 1.0 μmole of p-nitrophenolate anion produced per minute at 25° C., pH 4.8 from 1 mM p-nitrophenyl-beta-D-glucopyranoside as substrate in 50 mM sodium citrate containing 0.01% TWEEN® 20.
Beta-xylosidase: The term “beta-xylosidase” means a beta-D-xyloside xylohydrolase (E.C. 3.2.1.37) that catalyzes the exo-hydrolysis of short beta (1→4)-xylooligosaccharides to remove successive D-xylose residues from non-reducing termini. For purposes of the present invention, beta-xylosidase activity is determined using 1 mM p-nitrophenyl-beta-D-xyloside as substrate in 100 mM sodium citrate containing 0.01% TWEEN® 20 at pH 5, 40° C. One unit of beta-xylosidase is defined as 1.0 μmole of p-nitrophenolate anion produced per minute at 40° C., pH 5 from 1 mM p-nitrophenyl-beta-D-xyloside as substrate in 100 mM sodium citrate containing 0.01% TWEEN® 20.
Carbohydrate binding module: The term “carbohydrate binding module” means a domain within a carbohydrate-active enzyme that provides carbohydrate-binding activity (Boraston et al., 2004 , Biochem. J. 383: 769-781). A majority of known carbohydrate binding modules (CBMs) are contiguous amino acid sequences with a discrete fold. The carbohydrate binding module (CBM) is typically found either at the N-terminal or at the C-terminal extremity of an enzyme. The term “carbohydrate binding module” is also used interchangedly herein with the term “carbohydrate binding domain”.
Catalytic domain: The term “catalytic domain” means the region of an enzyme containing the catalytic machinery of the enzyme. In one aspect, the catalytic domain is amino acids 1 to 429 of SEQ ID NO: 2. In another aspect, the catalytic domain is amino acids 1 to 437 of SEQ ID NO: 8. In another aspect, the catalytic domain is amino acids 1 to 440 of SEQ ID NO: 10. In another aspect, the catalytic domain is amino acids 1 to 437 of SEQ ID NO: 12. In another aspect, the catalytic domain is amino acids 1 to 437 of SEQ ID NO: 14. In another aspect, the catalytic domain is amino acids 1 to 438 of SEQ ID NO: 16. In another aspect, the catalytic domain is amino acids 1 to 437 of SEQ ID NO: 18. In another aspect, the catalytic domain is amino acids 1 to 430 of SEQ ID NO: 20. In another aspect, the catalytic domain is amino acids 1 to 433 of SEQ ID NO: 22.
Catalytic domain coding sequence: The term “catalytic domain coding sequence” means a polynucleotide that encodes a domain catalyzing cellobiohydrolase activity. In one aspect, the catalytic domain coding sequence is nucleotides 52 to 1469 of SEQ ID NO: 1. In another aspect, the catalytic domain coding sequence is nucleotides 52 to 1389 of SEQ ID NO: 3. In another aspect, the catalytic domain coding sequence is nucleotides 52 to 1389 of SEQ ID NO: 4. In another aspect, the catalytic domain coding sequence is nucleotides 79 to 1389 of SEQ ID NO: 7. In another aspect, the catalytic domain coding sequence is nucleotides 52 to 1371 of SEQ ID NO: 9. In another aspect, the catalytic domain coding sequence is nucleotides 55 to 1482 of SEQ ID NO: 11. In another aspect, the catalytic domain coding sequence is nucleotides 76 to 1386 of SEQ ID NO: 13. In another aspect, the catalytic domain is nucleotides 76 to 1386 of SEQ ID NO: 15. In another aspect, the catalytic domain coding sequence is nucleotides 55 to 1504 of SEQ ID NO: 17. In another aspect, the catalytic domain coding sequence is nucleotides 61 to 1350 of SEQ ID NO: 19. In another aspect, the catalytic domain coding sequence is nucleotides 55 to 1353 of SEQ ID NO: 21.
cDNA: The term “cDNA” means a DNA molecule that can be prepared by reverse transcription from a mature, spliced, mRNA molecule obtained from a eukaryotic or prokaryotic cell. cDNA lacks intron sequences that may be present in the corresponding genomic DNA. The initial, primary RNA transcript is a precursor to mRNA that is processed through a series of steps, including splicing, before appearing as mature spliced mRNA.
Cellobiohydrolase: The term “cellobiohydrolase” means a 1,4-beta-D-glucan cellobiohydrolase (E.C. 3.2.1.91 and E.C. 3.2.1.176) that catalyzes the hydrolysis of 1,4-beta-D-glucosidic linkages in cellulose, cellooligosaccharides, or any beta-1,4-linked glucose containing polymer, releasing cellobiose from the reducing end (cellobiohydrolase I) or non-reducing end (cellobiohydrolase II) of the chain (Teeri, 1997 , Trends in Biotechnology 15: 160-167; Teeri et al., 1998 , Biochem. Soc. Trans. 26: 173-178). Cellobiohydrolase activity is determined according to the procedures described by Lever et al., 1972 , Anal. Biochem. 47: 273-279; van Tilbeurgh et al., 1982 , FEBS Letters, 149: 152-156; van Tilbeurgh and Claeyssens, 1985 , FEBS Letters, 187: 283-288; and Tomme et al., 1988 , Eur. J. Biochem. 170: 575-581. In the present invention, cellobiohydrolase activity is preferably determined according to Examples 8 and 9 herein.
Cellulolytic enzyme or cellulase: The term “cellulolytic enzyme” or “cellulase” means one or more (e.g., several) enzymes that hydrolyze a cellulosic material. Such enzymes include endoglucanase(s), cellobiohydrolase(s), beta-glucosidase(s), or combinations thereof. The two basic approaches for measuring cellulolytic enzyme activity include: (1) measuring the total cellulolytic enzyme activity, and (2) measuring the individual cellulolytic enzyme activities (endoglucanases, cellobiohydrolases, and beta-glucosidases) as reviewed in Zhang et al., 2006 , Biotechnology Advances 24: 452-481. Total cellulolytic activity is usually measured using insoluble substrates, including Whatman No 1 filter paper, microcrystalline cellulose, bacterial cellulose, algal cellulose, cotton, pretreated lignocellulose, etc. The most common total cellulolytic activity assay is the filter paper assay using Whatman No 1 filter paper as the substrate. The assay was established by the International Union of Pure and Applied Chemistry (IUPAC) (Ghose, 1987 , Pure Appl. Chem. 59: 257-68).
For purposes of the present invention, cellulolytic enzyme activity is determined by measuring the increase in hydrolysis of a cellulosic material by cellulolytic enzyme(s) under the following conditions: 1-50 mg of cellulolytic enzyme protein/g of cellulose in PCS (or other pretreated cellulosic material) for 3-7 days at a suitable temperature such as 25° C.-80° C., e.g., 30° C., 35° C., 40° C., 45° C., 50° C., 55° C., 60° C., 65° C., or 70° C., and a suitable pH such as 4-9, e.g., 5.0, 5.5, 6.0, 6.5, or 7.0, compared to a control hydrolysis without addition of cellulolytic enzyme protein. Typical conditions are 1 ml reactions, washed or unwashed PCS, 5% insoluble solids (dry weight), 50 mM sodium acetate pH 5, 1 mM MnSO 4 , 50° C., 55° C., or 60° C., 72 hours, sugar analysis by AMINEX® HPX-87H column chromatography (Bio-Rad Laboratories, Inc., Hercules, Calif., USA).
Cellulosic material: The term “cellulosic material” means any material containing cellulose. The predominant polysaccharide in the primary cell wall of biomass is cellulose, the second most abundant is hemicellulose, and the third is pectin. The secondary cell wall, produced after the cell has stopped growing, also contains polysaccharides and is strengthened by polymeric lignin covalently cross-linked to hemicellulose. Cellulose is a homopolymer of anhydrocellobiose and thus a linear beta-(1-4)-D-glucan, while hemicelluloses include a variety of compounds, such as xylans, xyloglucans, arabinoxylans, and mannans in complex branched structures with a spectrum of substituents. Although generally polymorphous, cellulose is found in plant tissue primarily as an insoluble crystalline matrix of parallel glucan chains. Hemicelluloses usually hydrogen bond to cellulose, as well as to other hemicelluloses, which help stabilize the cell wall matrix.
Cellulose is generally found, for example, in the stems, leaves, hulls, husks, and cobs of plants or leaves, branches, and wood of trees. The cellulosic material can be, but is not limited to, agricultural residue, herbaceous material (including energy crops), municipal solid waste, pulp and paper mill residue, waste paper, and wood (including forestry residue) (see, for example, Wiselogel et al., 1995, in Handbook on Bioethanol (Charles E. Wyman, editor), pp. 105-118, Taylor & Francis, Washington D.C.; Wyman, 1994 , Bioresource Technology 50: 3-16; Lynd, 1990 , Applied Biochemistry and Biotechnology 24/25: 695-719; Mosier et al., 1999, Recent Progress in Bioconversion of Lignocellulosics, in Advances in Biochemical Engineering/Biotechnology , T. Scheper, managing editor, Volume 65, pp. 23-40, Springer-Verlag, New York). It is understood herein that the cellulose may be in the form of lignocellulose, a plant cell wall material containing lignin, cellulose, and hemicellulose in a mixed matrix. In one aspect, the cellulosic material is any biomass material. In another aspect, the cellulosic material is lignocellulose, which comprises cellulose, hemicelluloses, and lignin.
In an embodiment, the cellulosic material is agricultural residue, herbaceous material (including energy crops), municipal solid waste, pulp and paper mill residue, waste paper, or wood (including forestry residue).
In another embodiment, the cellulosic material is arundo , bagasse, bamboo, corn cob, corn fiber, corn stover, miscanthus , rice straw, switchgrass, or wheat straw.
In another embodiment, the cellulosic material is aspen, eucalyptus , fir, pine, poplar, spruce, or willow.
In another embodiment, the cellulosic material is algal cellulose, bacterial cellulose, cotton linter, filter paper, microcrystalline cellulose (e.g., AVICEL®), or phosphoric-acid treated cellulose.
In another embodiment, the cellulosic material is an aquatic biomass. As used herein the term “aquatic biomass” means biomass produced in an aquatic environment by a photosynthesis process. The aquatic biomass can be algae, emergent plants, floating-leaf plants, or submerged plants.
The cellulosic material may be used as is or may be subjected to pretreatment, using conventional methods known in the art, as described herein. In a preferred aspect, the cellulosic material is pretreated.
Coding sequence: The term “coding sequence” means a polynucleotide, which directly specifies the amino acid sequence of a variant. The boundaries of the coding sequence are generally determined by an open reading frame, which begins with a start codon such as ATG, GTG or TTG and ends with a stop codon such as TAA, TAG, or TGA. The coding sequence may be a genomic DNA, cDNA, synthetic DNA, or a combination thereof.
Control sequences: The term “control sequences” means nucleic acid sequences necessary for expression of a polynucleotide encoding a variant of the present invention. Each control sequence may be native (i.e., from the same gene) or foreign (i.e., from a different gene) to the polynucleotide encoding the variant or native or foreign to each other. Such control sequences include, but are not limited to, a leader, polyadenylation sequence, propeptide sequence, promoter, signal peptide sequence, and transcription terminator. At a minimum, the control sequences include a promoter, and transcriptional and translational stop signals. The control sequences may be provided with linkers for the purpose of introducing specific restriction sites facilitating ligation of the control sequences with the coding region of the polynucleotide encoding a variant.
Endoglucanase: The term “endoglucanase” means a 4-(1,3;1,4)-beta-D-glucan 4-glucanohydrolase (E.C. 3.2.1.4) that catalyzes endohydrolysis of 1,4-beta-D-glycosidic linkages in cellulose, cellulose derivatives (such as carboxymethyl cellulose and hydroxyethyl cellulose), lichenin, beta-1,4 bonds in mixed beta-1,3-1,4 glucans such as cereal beta-D-glucans or xyloglucans, and other plant material containing cellulosic components. Endoglucanase activity can be determined by measuring reduction in substrate viscosity or increase in reducing ends determined by a reducing sugar assay (Zhang et al., 2006 , Biotechnology Advances 24: 452-481). For purposes of the present invention, endoglucanase activity is determined using carboxymethyl cellulose (CMC) as substrate according to the procedure of Ghose, 1987 , Pure and Appl. Chem. 59: 257-268, at pH 5, 40° C.
Expression: The term “expression” includes any step involved in the production of a variant including, but not limited to, transcription, post-transcriptional modification, translation, post-translational modification, and secretion.
Expression vector: The term “expression vector” means a linear or circular DNA molecule that comprises a polynucleotide encoding a variant and is operably linked to control sequences that provide for its expression.
Family 61 glycoside hydrolase: The term “Family 61 glycoside hydrolase” or “Family GH61” or “GH61” means a polypeptide falling into the glycoside hydrolase Family 61 according to Henrissat, 1991 , Biochem. J. 280: 309-316, and Henrissat, and Bairoch, 1996 , Biochem. J. 316: 695-696. The GH61 polypeptides have recently been classified as lytic polysaccharide monooxygenases (Quinlan et al., 2011 , Proc. Natl. Acad. Sci. USA 208: 15079-15084; Phillips et al., 2011 , ACS Chem. Biol. 6: 1399-1406; Lin et al., 2012 , Structure 20: 1051-1061) and are designated “Auxiliary Activity 9” or “AA9” polypeptides.
Feruloyl esterase: The term “feruloyl esterase” means a 4-hydroxy-3-methoxycinnamoyl-sugar hydrolase (EC 3.1.1.73) that catalyzes the hydrolysis of 4-hydroxy-3-methoxycinnamoyl (feruloyl) groups from esterified sugar, which is usually arabinose in natural biomass substrates, to produce ferulate (4-hydroxy-3-methoxycinnamate). Feruloyl esterase (FAE) is also known as ferulic acid esterase, hydroxycinnamoyl esterase, FAE-III, cinnamoyl ester hydrolase, FAEA, cinnAE, FAE-I, or FAE-II. For purposes of the present invention, feruloyl esterase activity is determined using 0.5 mM p-nitrophenylferulate as substrate in 50 mM sodium acetate pH 5.0. One unit of feruloyl esterase equals the amount of enzyme capable of releasing 1 μmole of p-nitrophenolate anion per minute at pH 5, 25° C.
Fragment: The term “fragment” means a polypeptide having one or more (e.g., several) amino acids absent from the amino and/or carboxyl terminus of a mature polypeptide; wherein the fragment has cellobiohydrolase activity. In one aspect, a fragment contains at least 420 amino acid residues, e.g., at least 445 amino acid residues or at least 470 amino acid residues of the mature polypeptide of SEQ ID NO: 2 or a variant thereof. In another aspect, a fragment contains at least 430 amino acid residues, e.g., at least 455 amino acid residues or at least 480 amino acid residues of the mature polypeptide of SEQ ID NO: 8 or a variant thereof. In another aspect, a fragment contains at least 380 amino acid residues, e.g., at least 400 amino acid residues or at least 420 amino acid residues of the mature polypeptide of SEQ ID NO: 10 or a variant thereof. In another aspect, a fragment contains at least 380 amino acid residues, e.g., at least 400 amino acid residues or at least 420 amino acid residues of the mature polypeptide of SEQ ID NO: 12 or a variant thereof. In another aspect, a fragment contains at least 430 amino acid residues, e.g., at least 455 amino acid residues or at least 480 amino acid residues of the mature polypeptide of SEQ ID NO: 14 or a variant thereof. In another aspect, a fragment contains at least 430 amino acid residues, e.g., at least 455 amino acid residues or at least 480 amino acid residues of the mature polypeptide of SEQ ID NO: 16 or a variant thereof. In another aspect, a fragment contains at least 380 amino acid residues, e.g., at least 400 amino acid residues or at least 420 amino acid residues of the mature polypeptide of SEQ ID NO: 18 or a variant thereof. In another aspect, a fragment contains at least 370 amino acid residues, e.g., at least 390 amino acid residues or at least 410 amino acid residues of the mature polypeptide of SEQ ID NO: 20 or a variant thereof. In another aspect, a fragment contains at least 435 amino acid residues, e.g., at least 460 amino acid residues or at least 485 amino acid residues of the mature polypeptide of SEQ ID NO: 22 or a variant thereof.
Hemicellulolytic enzyme or hemicellulase: The term “hemicellulolytic enzyme” or “hemicellulase” means one or more (e.g., several) enzymes that hydrolyze a hemicellulosic material. See, for example, Shallom and Shoham, 2003 , Current Opinion In Microbiology 6(3): 219-228). Hemicellulases are key components in the degradation of plant biomass. Examples of hemicellulases include, but are not limited to, an acetylmannan esterase, an acetylxylan esterase, an arabinanase, an arabinofuranosidase, a coumaric acid esterase, a feruloyl esterase, a galactosidase, a glucuronidase, a glucuronoyl esterase, a mannanase, a mannosidase, a xylanase, and a xylosidase. The substrates for these enzymes, hemicelluloses, are a heterogeneous group of branched and linear polysaccharides that are bound via hydrogen bonds to the cellulose microfibrils in the plant cell wall, crosslinking them into a robust network. Hemicelluloses are also covalently attached to lignin, forming together with cellulose a highly complex structure. The variable structure and organization of hemicelluloses require the concerted action of many enzymes for its complete degradation. The catalytic modules of hemicellulases are either glycoside hydrolases (GHs) that hydrolyze glycosidic bonds, or carbohydrate esterases (CEs), which hydrolyze ester linkages of acetate or ferulic acid side groups. These catalytic modules, based on homology of their primary sequence, can be assigned into GH and CE families. Some families, with an overall similar fold, can be further grouped into clans, marked alphabetically (e.g., GH-A). A most informative and updated classification of these and other carbohydrate active enzymes is available in the Carbohydrate-Active Enzymes (CAZy) database. Hemicellulolytic enzyme activities can be measured according to Ghose and Bisaria, 1987 , Pure & Appl. Chem. 59: 1739-1752, at a suitable temperature such as 40° C.-80° C., e.g., 50° C., 55° C., 60° C., 65° C., or 70° C., and a suitable pH such as 4-9, e.g., 5.0, 5.5, 6.0, 6.5, or 7.0.
High stringency conditions: The term “high stringency conditions” means for probes of at least 100 nucleotides in length, prehybridization and hybridization at 42° C. in 5× SSPE, 0.3% SDS, 200 micrograms/ml sheared and denatured salmon sperm DNA, and 50% formamide, following standard Southern blotting procedures for 12 to 24 hours. The carrier material is finally washed three times each for 15 minutes using 0.2×SSC, 0.2% SDS at 65° C.
Host cell: The term “host cell” means any cell type that is susceptible to transformation, transfection, transduction, or the like with a nucleic acid construct or expression vector comprising a polynucleotide of the present invention. The term “host cell” encompasses any progeny of a parent cell that is not identical to the parent cell due to mutations that occur during replication.
Improved property: The term “improved property” means a characteristic associated with a variant that is improved compared to the parent. Such an improved property is preferably increased specific performance.
Increased specific performance: The term “increased specific performance” by a variant of the present invention means improved conversion of a cellulosic material to a product, as compared to the same level of conversion by the parent. Increased specific performance is determined per unit protein (e.g., mg protein, or μmole protein). The increased specific performance of the variant relative to the parent can be assessed, for example, under one or more (e.g., several) conditions of pH, temperature, and substrate concentration. In one aspect, the product is glucose. In another aspect, the product is cellobiose. In another aspect, the product is glucose+cellobiose.
In one aspect, the condition is pH. For example, the pH can be any pH in the range of 3 to 7, e.g., 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, or 7.0 (or in between). Any suitable buffer for achieving the desired pH can be used.
In another aspect, the condition is temperature. For example, the temperature can be any temperature in the range of 25° C. to 90° C., e.g., 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, or 90° C. (or in between).
In another aspect, the condition is substrate concentration. Any cellulosic material defined herein can be used as the substrate. In one aspect, the substrate concentration is measured as the dry solids content. The dry solids content is preferably in the range of about 1 to about 50 wt %, e.g., about 5 to about 45 wt %, about 10 to about 40 wt %, or about 20 to about 30 wt %. In another aspect, the substrate concentration is measured as the insoluble glucan content. The insoluble glucan content is preferably in the range of about 2.5 to about 25 wt %, e.g., about 5 to about 20 wt % or about 10 to about 15 wt %.
In another aspect, a combination of two or more (e.g., several) of the above conditions are used to determine the increased specific performance of the variant relative to the parent, such as any temperature in the range of 25° C. to 90° C., e.g., 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, or 90° C. (or in between) at a pH in the range of 3 to 7, e.g., 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, or 7.0 (or in between).
The increased specific performance of the variant relative to the parent can be determined using any enzyme assay known in the art for cellobiohydrolases as described herein. Alternatively, the increased specific performance of the variant relative to the parent can be determined using the assays described in Examples 8 and 9.
In another aspect, the specific performance of the variant is at least 1.01-fold, e.g., at least 1.02-fold, at least 1.03-fold, at least 1.04-fold, at least 1.05-fold, at least 1.06-fold, at least 1.07-fold, at least 1.08-fold, at least 1.09-fold, at least 1.1-fold, at least 1.2-fold, at least 1.3-fold, at least 1.4-fold, at least 1.5-fold, at least 1.6-fold, at least 1.7-fold, at least 1.8-fold, at least 1.9-fold, at least 2-fold, at least 2.1-fold, at least 2.2-fold, at least 2.3-fold, at least 2.4-fold, at least 2.5-fold, at least 5-fold, at least 10-fold, at least 15-fold, at least 20-fold, at least 25-fold, and at least 50-fold higher than the specific performance of the parent.
Isolated: The term “isolated” means a substance in a form or environment that does not occur in nature. Non-limiting examples of isolated substances include (1) any non-naturally occurring substance, (2) any substance including, but not limited to, any enzyme, variant, nucleic acid, protein, peptide or cofactor, that is at least partially removed from one or more or all of the naturally occurring constituents with which it is associated in nature; (3) any substance modified by the hand of man relative to that substance found in nature; or (4) any substance modified by increasing the amount of the substance relative to other components with which it is naturally associated (e.g., recombinant production in a host cell; multiple copies of a gene encoding the substance; and use of a stronger promoter than the promoter naturally associated with the gene encoding the substance).
Low stringency conditions: The term “low stringency conditions” means for probes of at least 100 nucleotides in length, prehybridization and hybridization at 42° C. in 5×SSPE, 0.3% SDS, 200 micrograms/ml sheared and denatured salmon sperm DNA, and 25% formamide, following standard Southern blotting procedures for 12 to 24 hours. The carrier material is finally washed three times each for 15 minutes using 0.2×SSC, 0.2% SDS at 50° C.
Mature polypeptide: The term “mature polypeptide” means a polypeptide in its final form following translation and any post-translational modifications, such as N-terminal processing, C-terminal truncation, glycosylation, phosphorylation, etc. In one aspect, the mature polypeptide is amino acids 1 to 497 of SEQ ID NO: 2 based on the SignalP 3.0 program (Bendtsen et al., 2004 , J. Mol. Biol. 340: 783-795) that predicts amino acids −1 to −17 of SEQ ID NO: 2 are a signal peptide. In another aspect, the mature polypeptide is amino acids 1 to 506 of SEQ ID NO: 8 (P3EX) based on the SignalP 3.0 program that predicts amino acids −1 to −26 of SEQ ID NO: 8 are a signal peptide. In another aspect, the mature polypeptide is amino acids 1 to 440 of SEQ ID NO: 10 (P57J) based on the SignalP 3.0 program that predicts amino acids −1 to −17 of SEQ ID NO: 10 are a signal peptide. In another aspect, the mature polypeptide is amino acids 1 to 437 of SEQ ID NO: 12 (P82PH) based on the SignalP 3.0 program that predicts amino acids −1 to −18 of SEQ ID NO: 12 are a signal peptide. In another aspect, the mature polypeptide is amino acids 1 to 507 of SEQ ID NO: 14 (P23YSY) based on the SignalP 3.0 program that predicts amino acids −1 to −25 of SEQ ID NO: 14 are a signal peptide. In another aspect, the mature polypeptide is amino acids 1 to 507 of SEQ ID NO: 16 (P23YSX) based on the SignalP 3.0 program that predicts amino acids −1 to −25 of SEQ ID NO: 16 are a signal peptide. In another aspect, the mature polypeptide is amino acids 1 to 437 of SEQ ID NO: 18 (P24765) based on the SignalP 3.0 program that predicts amino acids −1 to −18 of SEQ ID NO: 18 are a signal peptide. In another aspect, the mature polypeptide is amino acids 1 to 430 of SEQ ID NO: 20 (P66Z) based on the SignalP 3.0 program that predicts amino acids −1 to −20 of SEQ ID NO: 20 are a signal peptide. In another aspect, the mature polypeptide is amino acids 1 to 511 of SEQ ID NO: 22 (P57G) based on the SignalP 3.0 program that predicts amino acids −1 to −18 of SEQ ID NO: 22 are a signal peptide. It is known in the art that a host cell may produce a mixture of two of more different mature polypeptides (i.e., with a different C-terminal and/or N-terminal amino acid) expressed by the same polynucleotide. It is also known in the art that different host cells may process polypeptides differently, and thus, one host cell expressing a polynucleotide may produce a different mature polypeptide (e.g., having a different C-terminal and/or N-terminal amino acid) as compared to another host cell expressing the same polynucleotide.
Mature polypeptide coding sequence: The term “mature polypeptide coding sequence” means a polynucleotide that encodes a mature polypeptide having cellobiohydrolase activity. In one aspect, the mature polypeptide coding sequence is nucleotides 52 to 1673 of SEQ ID NO: 1 (without the stop codon) based on SignalP 3.0 program (Bendtsen et al., 2004, supra) that predicts nucleotides 1 to 51 of SEQ ID NO: 1 encode a signal peptide. In another aspect, the mature polypeptide coding sequence is nucleotides 52 to 1542 of SEQ ID NO: 3 (without the stop codon) based on SignalP 3.0 program that predicts nucleotides 1 to 51 of SEQ ID NO: 3 encode a signal peptide. In another aspect, the mature polypeptide coding sequence is nucleotides 52 to 1542 of SEQ ID NO: 4 (without the stop codon) based on SignalP 3.0 program that predicts nucleotides 1 to 51 of SEQ ID NO: 4 encode a signal peptide. In another aspect, the mature polypeptide coding sequence is nucleotides 79 to 1596 of SEQ ID NO: 7 (D1R9) (without the stop codon) based on SignalP 3.0 program that predicts nucleotides 1 to 78 of SEQ ID NO: 7 encode a signal peptide. In another aspect, the mature polypeptide coding sequence is nucleotides 52 to 1371 of SEQ ID NO: 9 (D3FQ) (without the stop codon) based on SignalP 3.0 program that predicts nucleotides 1 to 51 of SEQ ID NO: 9 encode a signal peptide. In another aspect, the mature polypeptide coding sequence is nucleotides 55 to 1482 of SEQ ID NO: 11 (D23Y2) (without the stop codon) based on SignalP 3.0 program that predicts nucleotides 1 to 54 of SEQ ID NO: 11 encode a signal peptide. In another aspect, the mature polypeptide coding sequence is nucleotides 76 to 1596 of SEQ ID NO: 13 (D72PP3) (without the stop codon) based on SignalP 3.0 program that predicts nucleotides 1 to 75 of SEQ ID NO: 13 encode a signal peptide. In another aspect, the mature polypeptide coding sequence is nucleotides 76 to 1596 of SEQ ID NO: 15 (D72PP2) (without the stop codon) based on SignalP 3.0 program that predicts nucleotides 1 to 75 of SEQ ID NO: 15 encode a signal peptide. In another aspect, the mature polypeptide coding sequence is nucleotides 55 to 1504 of SEQ ID NO: 17 (D82ACF) (without the stop codon) based on SignalP 3.0 program that predicts nucleotides 1 to 54 of SEQ ID NO: 17 encode a signal peptide. In another aspect, the mature polypeptide coding sequence is nucleotides 61 to 1350 of SEQ ID NO: 19 (D6CT) (without the stop codon) based on SignalP 3.0 program that predicts nucleotides 1 to 60 of SEQ ID NO: 19 encode a signal peptide. In another aspect, the mature polypeptide coding sequence is nucleotides 55 to 1587 of SEQ ID NO: 21 (D3FP) (without the stop codon) based on SignalP 3.0 program that predicts nucleotides 1 to 54 of SEQ ID NO: 21 encode a signal peptide.
Medium stringency conditions: The term “medium stringency conditions” means for probes of at least 100 nucleotides in length, prehybridization and hybridization at 42° C. in 5×SSPE, 0.3% SDS, 200 micrograms/ml sheared and denatured salmon sperm DNA, and 35% formamide, following standard Southern blotting procedures for 12 to 24 hours. The carrier material is finally washed three times each for 15 minutes using 0.2×SSC, 0.2% SDS at 55° C.
Medium-high stringency conditions: The term “medium-high stringency conditions” means for probes of at least 100 nucleotides in length, prehybridization and hybridization at 42° C. in 5×SSPE, 0.3% SDS, 200 micrograms/ml sheared and denatured salmon sperm DNA, and 35% formamide, following standard Southern blotting procedures for 12 to 24 hours. The carrier material is finally washed three times each for 15 minutes using 0.2×SSC, 0.2% SDS at 60° C.
Mutant: The term “mutant” means a polynucleotide encoding a variant.
Nucleic acid construct: The term “nucleic acid construct” means a nucleic acid molecule, either single- or double-stranded, which is isolated from a naturally occurring gene or is modified to contain segments of nucleic acids in a manner that would not otherwise exist in nature or which is synthetic, which comprises one or more control sequences.
Operably linked: The term “operably linked” means a configuration in which a control sequence is placed at an appropriate position relative to the coding sequence of a polynucleotide such that the control sequence directs expression of the coding sequence.
Parent or parent cellobiohydrolase: The term “parent” or “parent cellobiohydrolase” means a polypeptide having cellobiohydrolase activity to which an alteration, i.e., a substitution, insertion, and/or deletion, at one or more (e.g., several) positions, is made to produce an enzyme variant of the present invention. The parent may be a naturally occurring (wild-type) polypeptide or a variant or fragment thereof.
Polypeptide having cellulolytic enhancing activity: The term “polypeptide having cellulolytic enhancing activity” means a GH61 polypeptide or variant thereof that catalyzes the enhancement of the hydrolysis of a cellulosic material by enzyme having cellulolytic activity, i.e., a cellulase. For purposes of the present invention, cellulolytic enhancing activity is determined by measuring the increase in reducing sugars or the increase of the total of cellobiose and glucose from the hydrolysis of a cellulosic material by cellulolytic enzyme under the following conditions: 1-50 mg of total protein/g of cellulose in pretreated corn stover (PCS), wherein total protein is comprised of 50-99.5% w/w cellulolytic enzyme protein and 0.5-50% w/w protein of a GH61 polypeptide or variant thereof for 1-7 days at a suitable temperature, such as 25° C.-80° C., e.g., 30° C., 35° C., 40° C., 45° C., 50° C., 55° C., 60° C., 65° C., or 70° C., and a suitable pH, such as 4-9, e.g., 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, or 8.5, compared to a control hydrolysis with equal total protein loading without cellulolytic enhancing activity (1-50 mg of cellulolytic protein/g of cellulose in PCS) In one aspect, GH61 polypeptide enhancing activity is determined using a mixture of CELLUCLAST® 1.5L (Novozymes A/S, Bagsvaerd, Denmark) in the presence of 2-3% of total protein weight Aspergillus oryzae beta-glucosidase (recombinantly produced in Aspergillus oryzae according to WO 02/095014) or 2-3% of total protein weight Aspergillus fumigatus beta-glucosidase (recombinantly produced in Aspergillus oryzae as described in WO 02/095014) of cellulase protein loading is used as the source of the cellulolytic activity.
Another assay for determining the cellulolytic enhancing activity of a GH61 polypeptide or variant thereof is to incubate the GH61 polypeptide or variant with 0.5% phosphoric acid swollen cellulose (PASO), 100 mM sodium acetate pH 5, 1 mM MnSO 4 , 0.1% gallic acid, 0.025 mg/ml of Aspergillus fumigatus beta-glucosidase, and 0.01% TRITON® X100 (4-(1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol) for 24-96 hours at 40° C. followed by determination of the glucose released from the PASO.
The GH61 polypeptides or variants thereof having cellulolytic enhancing activity enhance the hydrolysis of a cellulosic material catalyzed by enzyme having cellulolytic activity by reducing the amount of cellulolytic enzyme required to reach the same degree of hydrolysis preferably at least 1.01-fold, e.g., at least 1.05-fold, at least 1.10-fold, at least 1.25-fold, at least 1.5-fold, at least 2-fold, at least 3-fold, at least 4-fold, at least 5-fold, at least 10-fold, or at least 20-fold.
Pretreated corn stover: The term “Pretreated Corn Stover” or “PCS” means a cellulosic material derived from corn stover by treatment with heat and dilute sulfuric acid, alkaline pretreatment, neutral pretreatment, or any pretreatment known in the art.
Sequence identity: The relatedness between two amino acid sequences or between two nucleotide sequences is described by the parameter “sequence identity”.
For purposes of the present invention, the sequence identity between two amino acid sequences is determined using the Needleman-Wunsch algorithm (Needleman and Wunsch, 1970 , J. Mol. Biol. 48: 443-453) as implemented in the Needle program of the EMBOSS package (EMBOSS: The European Molecular Biology Open Software Suite, Rice et al., 2000 , Trends Genet. 16: 276-277), preferably version 5.0.0 or later. The parameters used are a gap open penalty of 10, a gap extension penalty of 0.5, and the EBLOSUM62 (EMBOSS version of BLOSUM62) substitution matrix. The output of Needle labeled “longest identity” (obtained using the −nobrief option) is used as the percent identity and is calculated as follows:
(Identical Residues×100)/(Length of Alignment−Total Number of Gaps in Alignment)
For purposes of the present invention, the sequence identity between two deoxyribonucleotide sequences is determined using the Needleman-Wunsch algorithm (Needleman and Wunsch, 1970, supra) as implemented in the Needle program of the EMBOSS package (EMBOSS: The European Molecular Biology Open Software Suite, Rice et al., 2000, supra), preferably version 5.0.0 or later. The parameters used are a gap open penalty of 10, a gap extension penalty of 0.5, and the EDNAFULL (EMBOSS version of NCBI NUC4.4) substitution matrix. The output of Needle labeled “longest identity” (obtained using the −nobrief option) is used as the percent identity and is calculated as follows:
(Identical Deoxyribonucleotides×100)/(Length of Alignment−Total Number of Gaps in Alignment)
Subsequence: The term “subsequence” means a polynucleotide having one or more (e.g., several) nucleotides absent from the 5′ and/or 3′ end of a mature polypeptide coding sequence; wherein the subsequence encodes a fragment having cellobiohydrolase activity. In one aspect, a subsequence contains at least 1400 nucleotides, e.g., at least 1475 nucleotides or at least 1550 nucleotides of the mature polypeptide coding sequence of SEQ ID NO: 1 or a mutant thereof. In another aspect, a subsequence contains at least 1260 nucleotides, e.g., at least 1335 nucleotides or at least 1410 nucleotides of the mature polypeptide coding sequence of SEQ ID NO: 3 or a mutant thereof. In another aspect, a subsequence contains at least 1260 nucleotides, e.g., at least 1335 nucleotides or at least 1410 nucleotides of the mature polypeptide coding sequence of SEQ ID NO: 4 or a mutant thereof. In another aspect, a fragment contains at least 1290 nucleotides, e.g., at least 1365 nucleotides or at least 1440 nucleotides of the mature polypeptide of SEQ ID NO: 7 or a mutant thereof. In another aspect, a fragment contains at least 1140 nucleotides, e.g., at least 1200 nucleotides or at least 1260 nucleotides of the mature polypeptide of SEQ ID NO: 9 or a mutant thereof. In another aspect, a fragment contains at least 1140 nucleotides, e.g., at least 1200 nucleotides or at least 1260 nucleotides of the mature polypeptide of SEQ ID NO: 11 or a mutant thereof. In another aspect, a fragment contains at least 1290 nucleotides, e.g., at least 1365 nucleotides or at least 1440 nucleotides of the mature polypeptide of SEQ ID NO: 13 or a mutant thereof. In another aspect, a fragment contains at least 1290 nucleotides, e.g., at least 1365 nucleotides or at least 1440 nucleotides of the mature polypeptide of SEQ ID NO: 15 or a mutant thereof. In another aspect, a fragment contains at least 1140 nucleotides, e.g., at least 1200 nucleotides or at least 1260 nucleotides of the mature polypeptide of SEQ ID NO: 17 or a mutant thereof. In another aspect, a fragment contains at least 1110 nucleotides, e.g., at least 1170 nucleotides or at least 1230 nucleotides of the mature polypeptide of SEQ ID NO: 19 or a mutant thereof. In another aspect, a fragment contains at least 1305 nucleotides, e.g., at least 1380 nucleotides or at least 1455 nucleotides of the mature polypeptide of SEQ ID NO: 21 or a mutant thereof.
Variant: The term “variant” means a polypeptide having cellobiohydrolase activity comprising an alteration, i.e., a substitution, insertion, and/or deletion, at one or more (e.g., several) positions. A substitution means replacement of the amino acid occupying a position with a different amino acid; a deletion means removal of the amino acid occupying a position; and an insertion means adding an amino acid adjacent to and immediately following the amino acid occupying a position. The variants of the present invention have a specific performance which is at least 1.01-fold higher than the specific performance of the parent.
Very high stringency conditions: The term “very high stringency conditions” means for probes of at least 100 nucleotides in length, prehybridization and hybridization at 42° C. in 5×SSPE, 0.3% SDS, 200 micrograms/ml sheared and denatured salmon sperm DNA, and 50% formamide, following standard Southern blotting procedures for 12 to 24 hours. The carrier material is finally washed three times each for 15 minutes using 0.2×SSC, 0.2% SDS at 70° C.
Very low stringency conditions: The term “very low stringency conditions” means for probes of at least 100 nucleotides in length, prehybridization and hybridization at 42° C. in 5×SSPE, 0.3% SDS, 200 micrograms/ml sheared and denatured salmon sperm DNA, and 25% formamide, following standard Southern blotting procedures for 12 to 24 hours. The carrier material is finally washed three times each for 15 minutes using 0.2×SSC, 0.2% SDS at 45° C.
Wild-type cellobiohydrolase: The term “wild-type” cellobiohydrolase means a cellobiohydrolase naturally produced by a microorganism, such as a bacterium, yeast, or filamentous fungus found in nature.
Xylan-containing material: The term “xylan-containing material” means any material comprising a plant cell wall polysaccharide containing a backbone of beta-(1-4)-linked xylose residues. Xylans of terrestrial plants are heteropolymers possessing a beta-(1-4)-D-xylopyranose backbone, which is branched by short carbohydrate chains. They comprise D-glucuronic acid or its 4-O-methyl ether, L-arabinose, and/or various oligosaccharides, composed of D-xylose, L-arabinose, D- or L-galactose, and D-glucose. Xylan-type polysaccharides can be divided into homoxylans and heteroxylans, which include glucuronoxylans, (arabino)glucuronoxylans, (glucurono)arabinoxylans, arabinoxylans, and complex heteroxylans. See, for example, Ebringerova et al., 2005 , Adv. Polym. Sci. 186: 1-67.
In the processes of the present invention, any material containing xylan may be used. In a preferred aspect, the xylan-containing material is lignocellulose.
Xylan degrading activity or xylanolytic activity: The term “xylan degrading activity” or “xylanolytic activity” means a biological activity that hydrolyzes xylan-containing material. The two basic approaches for measuring xylanolytic activity include: (1) measuring the total xylanolytic activity, and (2) measuring the individual xylanolytic activities (e.g., endoxylanases, beta-xylosidases, arabinofuranosidases, alpha-glucuronidases, acetylxylan esterases, feruloyl esterases, and alpha-glucuronyl esterases). Recent progress in assays of xylanolytic enzymes was summarized in several publications including Biely and Puchard, 2006 , Journal of the Science of Food and Agriculture 86(11): 1636-1647; Spanikova and Biely, 2006 , FEBS Letters 580(19): 4597-4601; Herrimann et al., 1997 , Biochemical Journal 321: 375-381.
Total xylan degrading activity can be measured by determining the reducing sugars formed from various types of xylan, including, for example, oat spelt, beechwood, and larchwood xylans, or by photometric determination of dyed xylan fragments released from various covalently dyed xylans. A common total xylanolytic activity assay is based on production of reducing sugars from polymeric 4-O-methyl glucuronoxylan as described in Bailey et al., 1992, Interlaboratory testing of methods for assay of xylanase activity, Journal of Biotechnology 23(3): 257-270. Xylanase activity can also be determined with 0.2% AZCL-arabinoxylan as substrate in 0.01% TRITON® X-100 and 200 mM sodium phosphate pH 6 at 37° C. One unit of xylanase activity is defined as 1.0 μmole of azurine produced per minute at 37° C., pH 6 from 0.2% AZCL-arabinoxylan as substrate in 200 mM sodium phosphate pH 6.
For purposes of the present invention, xylan degrading activity is determined by measuring the increase in hydrolysis of birchwood xylan (Sigma Chemical Co., Inc., St. Louis, Mo., USA) by xylan-degrading enzyme(s) under the following typical conditions: 1 ml reactions, 5 mg/ml substrate (total solids), 5 mg of xylanolytic protein/g of substrate, 50 mM sodium acetate pH 5, 50° C., 24 hours, sugar analysis using p-hydroxybenzoic acid hydrazide (PHBAH) assay as described by Lever, 1972 , Anal. Biochem 47: 273-279.
Xylanase: The term “xylanase” means a 1,4-beta-D-xylan-xylohydrolase (E.C. 3.2.1.8) that catalyzes the endohydrolysis of 1,4-beta-D-xylosidic linkages in xylans. For purposes of the present invention, xylanase activity is determined with 0.2% AZCL-arabinoxylan as substrate in 0.01% TRITON® X-100 and 200 mM sodium phosphate pH 6 at 37° C. One unit of xylanase activity is defined as 1.0 μmole of azurine produced per minute at 37° C., pH 6 from 0.2% AZCL-arabinoxylan as substrate in 200 mM sodium phosphate pH 6.
Conventions for Designation of Variants
For purposes of the present invention, the sequence of SEQ ID NO: 2 is used to determine the corresponding amino acid residue in another cellobiohydrolase. The amino acid sequence of another cellobiohydrolase is aligned with SEQ ID NO: 2, and based on the alignment, the amino acid position number corresponding to any amino acid residue in SEQ ID NO: 2 is determined using the Needleman-Wunsch algorithm (Needleman and Wunsch, 1970 , J. Mol. Biol. 48: 443-453) as implemented in the Needle program of the EMBOSS package (EMBOSS: The European Molecular Biology Open Software Suite, Rice et al., 2000 , Trends Genet. 16: 276-277), preferably version 5.0.0 or later. The parameters used are a gap open penalty of 10, a gap extension penalty of 0.5, and the EBLOSUM62 (EMBOSS version of BLOSUM62) substitution matrix. Numbering of the amino acid positions is based on the full-length polypeptide (e.g., including the signal peptide) of SEQ ID NO: 2 wherein position −17 is the first amino acid of the signal peptide (i.e., Met) and position 1 is Gln of SEQ ID NO: 2. For example, the position corresponding to position 197 of the Trichoderma reesei cellobiohydrolase I (SEQ ID NO: 2) is position 194 of the Rasamsonia emersonii cellobiohydrolase I, and position 200 of the Trichoderma reesei cellobiohydrolase I is position 197 of the Rasamsonia emersonii cellobiohydrolase I.
Identification of the corresponding amino acid residue in another cellobiohydrolase can be determined by an alignment of multiple polypeptide sequences using several computer programs including, but not limited to, MUSCLE (multiple sequence comparison by log-expectation; version 3.5 or later; Edgar, 2004 , Nucleic Acids Research 32: 1792-1797), MAFFT (version 6.857 or later; Katoh and Kuma, 2002 , Nucleic Acids Research 30: 3059-3066; Katoh et al., 2005 , Nucleic Acids Research 33: 511-518; Katoh and Toh, 2007 , Bioinformatics 23: 372-374; Katoh et al., 2009 , Methods in Molecular Biology 537: 39-64; Katoh and Toh, 2010 , Bioinformatics 26: 1899-1900), and EMBOSS EMMA employing ClustalW (1.83 or later; Thompson et al., 1994 , Nucleic Acids Research 22: 4673-4680), using their respective default parameters.
When another cellobiohydrolase has diverged from the sequence of SEQ ID NO: 2 such that traditional sequence-based comparison fails to detect their relationship (Lindahl and Elofsson, 2000 , J. Mol. Biol. 295: 613-615), other pairwise sequence comparison algorithms can be used. Greater sensitivity in sequence-based searching can be attained using search programs that utilize probabilistic representations of polypeptide families (profiles) to search databases. For example, the PSI-BLAST program generates profiles through an iterative database search process and is capable of detecting remote homologs (Atschul et al., 1997 , Nucleic Acids Res. 25: 3389-3402). Even greater sensitivity can be achieved if the family or superfamily for the polypeptide has one or more representatives in the protein structure databases. Programs such as GenTHREADER (Jones, 1999 , J. Mol. Biol. 287: 797-815; McGuffin and Jones, 2003 , Bioinformatics 19: 874-881) utilize information from a variety of sources (PSI-BLAST, secondary structure prediction, structural alignment profiles, and solvation potentials) as input to a neural network that predicts the structural fold for a query sequence. Similarly, the method of Gough et al., 2000 , J. Mol. Biol. 313: 903-919, can be used to align a sequence of unknown structure with the superfamily models present in the SCOP database. These alignments can in turn be used to generate homology models for the polypeptide, and such models can be assessed for accuracy using a variety of tools developed for that purpose.
For proteins of known structure, several tools and resources are available for retrieving and generating structural alignments. For example the SCOP superfamilies of proteins have been structurally aligned, and those alignments are accessible and downloadable. Two or more protein structures can be aligned using a variety of algorithms such as the distance alignment matrix (Holm and Sander, 1998 , Proteins 33: 88-96) or combinatorial extension (Shindyalov and Bourne, 1998 , Protein Engineering 11: 739-747), and implementation of these algorithms can additionally be utilized to query structure databases with a structure of interest in order to discover possible structural homologs (e.g., Holm and Park, 2000 , Bioinformatics 16: 566-567).
In describing the cellobiohydrolase variants of the present invention, the nomenclature described below is adapted for ease of reference. The accepted IUPAC single letter or three letter amino acid abbreviation is employed.
Substitutions.
For an amino acid substitution, the following nomenclature is used: Original amino acid, position, substituted amino acid. Accordingly, the substitution of threonine at position 226 with alanine is designated as “Thr226Ala” or “T226A”. Multiple mutations are separated by addition marks (“+”), e.g., “Gly205Arg+Ser411Phe” or “G205R+S411F”, representing substitutions at positions 205 and 411 of glycine (G) with arginine (R) and serine (S) with phenylalanine (F), respectively.
Deletions.
For an amino acid deletion, the following nomenclature is used: Original amino acid, position, *. Accordingly, the deletion of glycine at position 195 is designated as “Gly195*” or “G195*”. Multiple deletions are separated by addition marks (“+”), e.g., “Gly195*+Ser411*” or “G195*+S411*”.
Insertions.
For an amino acid insertion, the following nomenclature is used: Original amino acid, position, original amino acid, inserted amino acid. Accordingly the insertion of lysine after glycine at position 195 is designated “Gly195GlyLys” or “G195GK”. An insertion of multiple amino acids is designated [Original amino acid, position, original amino acid, inserted amino acid #1, inserted amino acid #2; etc.]. For example, the insertion of lysine and alanine after glycine at position 195 is indicated as “Gly195GlyLysAla” or “G195GKA”.
In such cases the inserted amino acid residue(s) are numbered by the addition of lower case letters to the position number of the amino acid residue preceding the inserted amino acid residue(s). In the above example, the sequence would thus be:
Parent:
Variant:
195
195 195a 195b
G
G-K-A
Multiple Alterations.
Variants comprising multiple alterations are separated by addition marks (“+”), e.g., “Arg170Tyr+Gly195Glu” or “R170Y+G195E” representing a substitution of arginine and glycine at positions 170 and 195 with tyrosine and glutamic acid, respectively.
Different Alterations.
Where different alterations can be introduced at a position, the different alterations are separated by a comma, e.g., “Arg170Tyr,Glu” represents a substitution of arginine at position 170 with tyrosine or glutamic acid. Thus, “Tyr167Gly,Ala+Arg170Gly,Ala” designates the following variants:
“Tyr167Gly+Arg170Gly”, “Tyr167Gly+Arg170Ala”, “Tyr167Ala+Arg170Gly”, and “Tyr167Ala+Arg170Ala”.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to cellobiohydrolase variants, comprising deletions at two or more consecutive positions of the B2-loop, wherein the variants have cellobiohydrolase activity.
The present invention also relates to isolated cellobiohydrolase variants, comprising a deletion at one or more positions corresponding to positions 195, 196, 197, 198, and 199 of SEQ ID NO: 2, and wherein the variants have cellobiohydrolase activity.
Variants
In an embodiment, the variant has a sequence identity of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100%, to the amino acid sequence of the parent cellobiohydrolase or the mature polypeptide thereof.
In another embodiment, the variant has at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100%, sequence identity to the mature polypeptide of SEQ ID NO: 2.
In another embodiment, the variant has at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100%, sequence identity to the mature polypeptide of SEQ ID NO: 8.
In another embodiment, the variant has at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100%, sequence identity to the mature polypeptide of SEQ ID NO: 10.
In another embodiment, the variant has at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100%, sequence identity to the mature polypeptide of SEQ ID NO: 12.
In another embodiment, the variant has at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100%, sequence identity to the mature polypeptide of SEQ ID NO: 14.
In another embodiment, the variant has at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100%, sequence identity to the mature polypeptide of SEQ ID NO: 16.
In another embodiment, the variant has at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100%, sequence identity to the mature polypeptide of SEQ ID NO: 18.
In another embodiment, the variant has at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100%, sequence identity to the mature polypeptide of SEQ ID NO: 20.
In another embodiment, the variant has at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100%, sequence identity to the mature polypeptide of SEQ ID NO: 22.
In one aspect, the number of alterations (e.g., substitutions and/or deletions) in the variants of the present invention is 1-4, e.g., 1, 2, 3, or 4 alterations. In another aspect, the number of substitutions and/or deletions in the variants of the present invention is 1-3, e.g., 1, 2, or 3 substitutions. In another aspect, the number of deletions in the variants of the present invention is 1 deletion.
In one aspect, a variant comprises or consists of deletions at two or more consecutive positions of the B2-loop. In one embodiment, the variant comprises deletions at positions corresponding to positions 194 and 195 of SEQ ID NO: 2 (e.g., P194*+S195*). In another embodiment, the variant comprises deletions at positions corresponding to positions 195 and 196 of SEQ ID NO: 2 (e.g., S195*+S196*, or S195*+A196*). In another embodiment, the variant comprises deletions at positions corresponding to positions 196 and 197 of SEQ ID NO: 2 (e.g., S196*+N197*, or A196*+N197*). In another embodiment, the variant comprises deletions at positions corresponding to positions 197 and 198 of SEQ ID NO: 2 (e.g., N197*+N198*, N197*+D198*). In another embodiment, the variant comprises deletions at positions corresponding to positions 198 and 199 of SEQ ID NO: 2 (e.g., N198*+A199*, D198*+A199*, or D198*+P199*). In another embodiment, the variant comprises deletions at positions corresponding to positions 199 and 200 of SEQ ID NO: 2 (e.g., A199*+N200*, or P199*+N200*). In another embodiment, the variant comprises deletions at positions corresponding to positions 200 and 201 of SEQ ID NO: 2 (e.g., N200*+T201*, N200*+A201*, or N200*+S201*).
In another aspect, a variant comprises or consists of deletions at three or more consecutive positions of the B2-loop (e.g., deletions at positions corresponding to positions 194*+195*+196*, 195*+196*+197*, 196*+197*+198*, 197*+198*+199*, 198*+199*+200*, or 199*+200*+201* of SEQ ID NO: 2).
In another aspect, a variant comprises or consists of deletions at four or more consecutive positions of the B2-loop (e.g., deletions at positions corresponding to positions 194*+195*+196*+197*, 195*+196*+197*+198*, 196*+197*+198*+199*, 197*+198*+199*+200*, or 198*+199*+200*+201* of SEQ ID NO: 2).
In another aspect, a variant comprises or consists of deletions at five or more consecutive positions of the B2-loop (e.g., deletions at positions corresponding to positions 194*+195*+196*+197*+198*, 195*+196*+197*+198*+199*, 196*+197*+198*+199*+200*, or 197*+198*+199*+200*+201* of SEQ ID NO: 2).
In another aspect, a variant comprises or consists of deletions at six or more consecutive positions of the B2-loop. (e.g., deletions at positions corresponding to positions 194*+195*+196*+197*+198*+199*, 195*+196*+197*+198*+199*+200*, or 196*+197*+198*+199*+200*+201* of SEQ ID NO: 2).
In another aspect, a variant comprises or consists of deletions at seven or more consecutive positions of the B2-loop (e.g., deletions at positions corresponding to positions 194*+195*+196*+197*+198*+199*+200*, or 195*+196*+197*+198*+199*+200*+201* of SEQ ID NO: 2).
In one aspect, a variant comprises or consists of deletions at eight consecutive positions of the B2-loop (e.g., deletions at positions corresponding to positions 194*+195*+196*+197*+198*+199*+200*+201* of SEQ ID NO: 2).
In another aspect, a variant comprises a deletion at one or more (e.g., several) positions corresponding to positions 195, 196, 197, and 198 of SEQ ID NO: 2.
In one aspect, the variant comprises or consists of a deletion at one position corresponding to positions 195, 196, 197, and 198 of SEQ ID NO: 2. In one embodiment, the variant comprises or consists of a deletion at a position corresponding to position 195 of SEQ ID NO: 2. In one embodiment, the deletion is an S195* deletion. In another embodiment, the variant comprises or consists of a deletion at a position corresponding to position 196 of SEQ ID NO: 2. In one embodiment, the deletion is an S196* deletion. In another embodiment, the variant comprises or consists of a deletion at a position corresponding to position 197 of SEQ ID NO: 2. In one embodiment, the deletion is an N197* deletion. In another embodiment, the variant comprises or consists of a deletion at a position corresponding to position 198 of SEQ ID NO: 2. In one embodiment, the deletion is an N198* deletion. In any of these embodiments, the variant may further comprise a substitution at any position corresponding positions 197, 198, and 200, and/or a deletion at a position corresponding to position 199 of SEQ ID NO: 2, as described infra.
In another aspect, a variant comprises or consists of a deletion at two positions corresponding to any of positions 195, 196, 197, and 198 of SEQ ID NO: 2. In one embodiment, the variant comprises or consists of deletions at positions corresponding to positions 195 and 196 of SEQ ID NO: 2. In one embodiment, the deletions are S195*+S196* deletions. In one embodiment, the variant comprises or consists of deletions at positions corresponding to positions 195 and 197 of SEQ ID NO: 2. In one embodiment, the deletions are S195*+N197* deletions. In one embodiment, the variant comprises or consists of deletions at positions corresponding to positions 195 and 198 of SEQ ID NO: 2. In one embodiment, the deletions are S195*+N198* deletions. In one embodiment, the variant comprises or consists of deletions at positions corresponding to positions 196 and 197 of SEQ ID NO: 2. In one embodiment, the deletions are S196*+N197* deletions. In one embodiment, the variant comprises or consists of deletions at positions corresponding to positions 196 and 198 of SEQ ID NO: 2. In one embodiment, the deletions are S196*+N198* deletions. In one embodiment, the variant comprises or consists of deletions at positions corresponding to positions 197 and 198 of SEQ ID NO: 2. In one embodiment, the deletions are N197*+N198* deletions. In any of these embodiments, the variant may further comprise a substitution at any position corresponding positions 197, 198, and 200, and/or a deletion at a position corresponding to position 199 of SEQ ID NO: 2, as described infra.
In another aspect, a variant comprises a deletion at positions corresponding to positions 196, 197, and 198 of SEQ ID NO: 2. In one embodiment, the deletions are S196*+N197*+N198* deletions. In one embodiment, the variant may further comprise a substitution at a position corresponding position 200, and/or a deletion at a position corresponding to position 199 of SEQ ID NO: 2, as described infra.
In another aspect, a variant comprises a deletion at each position corresponding to positions 195, 196, 197, and 198 of SEQ ID NO: 2. In one embodiment, the deletions are S195*+S196*+N197*+N198* deletions. In one embodiment, the variant may further comprise a substitution at a position corresponding position 200, and/or a deletion at a position corresponding to position 199 of SEQ ID NO: 2, as described infra.
In one embodiment, the variant comprises or consists of amino acids 1-434 of SEQ ID NO: 78. In another embodiment, the variant comprises or consists of amino acids 1-495 of SEQ ID NO: 80. In another embodiment, the variant comprises or consists of amino acids 1-495 of SEQ ID NO: 82.
The variants may further comprise one or more additional alterations, e.g., substitutions, insertions, or deletions at one or more (e.g., several) other positions, such as a substitution, a deletion, and/or an insertion at one or more (e.g., several) other positions disclosed in PCT/US2014/022068, WO 2011/050037, WO 2005/028636, WO 2005/001065, WO 2004/016760, and U.S. Pat. No. 7,375,197, which are incorporated herein in their entireties.
For example, in one aspect, the variant comprises an alteration at one or more positions corresponding to positions 197, 198, 199, and 200 of SEQ ID NO: 2, wherein the alteration at the one or more positions corresponding to positions 197, 198, and 200 is a substitution and the alteration at the position corresponding to position 199 is a deletion. In another aspect, a variant comprises an alteration at two positions corresponding to any of positions 197, 198, 199, and 200 of SEQ ID NO: 2, wherein the alteration at the one or more positions corresponding to positions 197, 198, and 200 is a substitution and the alteration at the position corresponding to position 199 is a deletion. In another aspect, a variant comprises an alteration at three positions corresponding to any of positions 197, 198, 199, and 200 of SEQ ID NO: 2, wherein the alteration at the one or more positions corresponding to positions 197, 198, and 200 is a substitution and the alteration at the position corresponding to position 199 is a deletion. In another aspect, a variant comprises a substitution at each position corresponding to positions 197, 198, and 200 and a deletion at a position corresponding to position 199.
In another aspect, the variant comprises a substitution at a position corresponding to position 197. In another aspect, the amino acid at a position corresponding to position 197 is substituted with Ala, Arg, Asn, Asp, Cys, Gln, Glu, Gly, His, Ile, Leu, Lys, Met, Phe, Pro, Ser, Thr, Trp, Tyr, or Val, preferably with Ala. In another aspect, the variant comprises the substitution N197A of SEQ ID NO: 2.
In another aspect, the variant comprises a substitution at a position corresponding to position 198. In another aspect, the amino acid at a position corresponding to position 198 is substituted with Ala, Arg, Asn, Asp, Cys, Gln, Glu, Gly, His, Ile, Leu, Lys, Met, Phe, Pro, Ser, Thr, Trp, Tyr, or Val, preferably with Ala. In another aspect, the variant comprises the substitution N198A of SEQ ID NO: 2.
In another aspect, the variant comprises a deletion at a position corresponding to position 199. In another aspect, the amino acid at a position corresponding to position 199 is Ala, Arg, Asn, Asp, Cys, Gln, Glu, Gly, His, Ile, Leu, Lys, Met, Phe, Pro, Ser, Thr, Trp, Tyr, or Val, preferably Ala. In another aspect, the variant comprises the deletion A199* of SEQ ID NO: 2.
In another aspect, the variant comprises a substitution at a position corresponding to position 200. In another aspect, the amino acid at a position corresponding to position 200 is substituted with Ala, Arg, Asn, Asp, Cys, Gln, Glu, Gly, His, Ile, Leu, Lys, Met, Phe, Pro, Ser, Thr, Trp, Tyr, or Val, preferably with Ala, Gly, or Trp. In another aspect, the variant comprises the substitution N200A,G,W of SEQ ID NO: 2.
In another aspect, the variant comprises an alteration at positions corresponding to positions 197 and 198, such as those described above.
In another aspect, the variant comprises alterations at positions corresponding to positions 197 and 199, such as those described above.
In another aspect, the variant comprises alterations at positions corresponding to positions 197 and 200, such as those described above.
In another aspect, the variant comprises alterations at positions corresponding to positions 198 and 199, such as those described above.
In another aspect, the variant comprises alterations at positions corresponding to positions 198 and 200, such as those described above.
In another aspect, the variant comprises alterations at positions corresponding to positions 199 and 200, such as those described above.
In another aspect, the variant comprises alterations at positions corresponding to positions 197, 198, and 199, such as those described above.
In another aspect, the variant comprises alterations at positions corresponding to positions 197, 198, and 200, such as those described above.
In another aspect, the variant comprises alterations at positions corresponding to positions 197, 199, and 200, such as those described above.
In another aspect, the variant comprises alterations at positions corresponding to positions 198, 199, and 200, such as those described above.
In another aspect, the variant comprises alterations at positions corresponding to positions 197, 198, 199, and 200, such as those described above.
In another aspect, the variant comprises one or more alterations selected from the group consisting of N197A, N198A, A199*, and N200A,G,W.
In another aspect, the variant comprises the alterations N197A+N198A of SEQ ID NO: 2.
In another aspect, the variant comprises the alterations N197A+A199* of SEQ ID NO: 2.
In another aspect, the variant comprises the alterations N197A+N200A,G,W of SEQ ID NO: 2.
In another aspect, the variant comprises the alterations N198A+A199* of SEQ ID NO: 2.
In another aspect, the variant comprises the alterations N198A+N200A,G,W of SEQ ID NO: 2.
In another aspect, the variant comprises the alterations A199*+N200A,G,W of SEQ ID NO: 2.
In another aspect, the variant comprises the alterations N197A+N198A+A199* of SEQ ID NO: 2.
In another aspect, the variant comprises the alterations N197A+N198A+N200A,G,W of SEQ ID NO: 2.
In another aspect, the variant comprises the alterations N197A+A199*+N200A,G,W of SEQ ID NO: 2.
In another aspect, the variant comprises the alterations N198A+A199*+N200A,G,W of SEQ ID NO: 2.
In another aspect, the variant comprises the alterations N197A+N198A+A199*+N200A,G,W of SEQ ID NO: 2.
The variants may further comprise one or more additional alterations, e.g., substitutions, insertions, or deletions at one or more (e.g., several) other positions.
The amino acid changes may be of a minor nature, that is conservative amino acid substitutions or insertions that do not significantly affect the folding and/or activity of the protein; small deletions, typically of 1-30 amino acids; small amino- or carboxyl-terminal extensions, such as an amino-terminal methionine residue; a small linker peptide of up to 20-25 residues; or a small extension that facilitates purification by changing net charge or another function, such as a poly-histidine tract, an antigenic epitope or a binding domain.
Examples of conservative substitutions are within the groups of basic amino acids (arginine, lysine and histidine), acidic amino acids (glutamic acid and aspartic acid), polar amino acids (glutamine and asparagine), hydrophobic amino acids (leucine, isoleucine and valine), aromatic amino acids (phenylalanine, tryptophan and tyrosine), and small amino acids (glycine, alanine, serine, threonine and methionine). Amino acid substitutions that do not generally alter specific activity are known in the art and are described, for example, by H. Neurath and R. L. Hill, 1979, In, The Proteins , Academic Press, New York. Common substitutions are Ala/Ser, Val/Ile, Asp/Glu, Thr/Ser, Ala/Gly, Ala/Thr, Ser/Asn, Ala/Val, Ser/Gly, Tyr/Phe, Ala/Pro, Lys/Arg, Asp/Asn, Leu/Ile, Leu/Val, Ala/Glu, and Asp/Gly.
Alternatively, the amino acid changes are of such a nature that the physico-chemical properties of the polypeptides are altered. For example, amino acid changes may improve the thermal stability of the polypeptide, alter the substrate specificity, change the pH optimum, and the like.
The variants may even further comprise one or more (e.g., several) substitutions at positions corresponding to positions disclosed in WO 2011/050037, WO 2011/050037, WO 2005/02863, WO 2005/001065, WO 2004/016760, and U.S. Pat. No. 7,375,197, which are incorporated herein in their entireties.
Essential amino acids in a polypeptide can be identified according to procedures known in the art, such as site-directed mutagenesis or alanine-scanning mutagenesis (Cunningham and Wells, 1989 , Science 244: 1081-1085). In the latter technique, single alanine mutations are introduced at every residue in the molecule, and the resultant mutant molecules are tested for cellobiohydrolase activity to identify amino acid residues that are critical to the activity of the molecule. See also, Hilton et al., 1996 , J. Biol. Chem. 271: 4699-4708. The active site of the enzyme or other biological interaction can also be determined by physical analysis of structure, as determined by such techniques as nuclear magnetic resonance, crystallography, electron diffraction, or photoaffinity labeling, in conjunction with mutation of putative contact site amino acids. See, for example, de Vos et al., 1992 , Science 255: 306-312; Smith et al., 1992 , J. Mol. Biol. 224: 899-904; Wlodaver et al., 1992 , FEBS Lett. 309: 59-64. The identity of essential amino acids can also be inferred from an alignment with a related polypeptide.
The variants may consist of 370 to 507 amino acids, e.g., 370 to 380, 380 to 390, 390 to 400, 400 to 410, 410 to 420, 420 to 430, 430 to 440, 450 to 460, 460 to 470, 470 to 480, 480 to 490, 490 to 500, or 500 to 507 amino acids.
In each of the embodiments described above, a variant of the present invention may be a hybrid polypeptide (chimera) in which a region of the variant is replaced with a region of another polypeptide. In one aspect, the region is a carbohydrate binding domain. The carbohydrate binding domain of a variant may be replaced with another (heterologous) carbohydrate binding domain.
In each of the embodiments described above, a variant of the present invention may be a fusion polypeptide or cleavable fusion polypeptide in which another polypeptide is fused at the N-terminus or the C-terminus of the variant. In one aspect, the other polypeptide is a carbohydrate binding domain. The catalytic domain of a variant of the present invention without a carbohydrate binding domain may be fused to a carbohydrate binding domain. A fusion polypeptide is produced by fusing a polynucleotide encoding another polypeptide to a polynucleotide encoding a variant of the present invention. Techniques for producing fusion polypeptides are known in the art, and include ligating the coding sequences encoding the polypeptides so that they are in frame and expression of the fusion polypeptide is under control of the same promoter(s) and terminator. Fusion polypeptides may also be constructed using intein technology in which fusion polypeptides are created post-translationally (Cooper et al., 1993 , EMBO J. 12: 2575-2583; Dawson et al., 1994 , Science 266: 776-779).
A fusion polypeptide can further comprise a cleavage site between the two polypeptides. Upon secretion of the fusion protein, the site is cleaved releasing the two polypeptides. Examples of cleavage sites include, but are not limited to, the sites disclosed in Martin et al., 2003 , J. Ind. Microbiol. Biotechnol. 3: 568-576; Svetina et al., 2000 , J. Biotechnol. 76: 245-251; Rasmussen-Wilson et al., 1997 , Appl. Environ. Microbiol. 63: 3488-3493; Ward et al., 1995 , Biotechnology 13: 498-503; and Contreras et al., 1991 , Biotechnology 9: 378-381; Eaton et al., 1986 , Biochemistry 25: 505-512; Collins-Racie et al., 1995 , Biotechnology 13: 982-987; Carter et al., 1989 , Proteins: Structure, Function, and Genetics 6: 240-248; and Stevens, 2003 , Drug Discovery World 4: 35-48.
In one embodiment, the variant is a hybrid or chimeric polypeptide in which the carbohydrate binding domain of the variant is replaced with a different carbohydrate binding domain. In another embodiment, the variant is a fusion protein in which a heterologous carbohydrate binding domain is fused to the variant. In one aspect, the carbohydrate binding domain is fused to the N-terminus of the variant. In another aspect, the carbohydrate binding domain is fused to the C-terminus of the variant. In another aspect, the fusion protein variant comprises or consists of SEQ ID NO: 78 or the mature polypeptide thereof. SEQ ID NO: 78 is encoded by SEQ ID NO: 77.
In an embodiment, the variant has increased specific performance compared to the parent enzyme.
Parent Cellobiohydrolases
The parent cellobiohydrolase may be any cellobiohydrolase I.
In one embodiment, the parent cellobiohydrolase may be (a) a polypeptide having at least 60% sequence identity to the mature polypeptide of SEQ ID NO: 2; (b) a polypeptide encoded by a polynucleotide that hybridizes under low stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, or SEQ ID NO: 4; or the full-length complement thereof; or (c) a polypeptide encoded by a polynucleotide having at least 60% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, or SEQ ID NO: 4.
In another embodiment, the parent cellobiohydrolase may also be (a) a polypeptide having at least 60% sequence identity to the mature polypeptide of SEQ ID NO: 8; (b) a polypeptide encoded by a polynucleotide that hybridizes under low stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 7; or the full-length complement thereof; or (c) a polypeptide encoded by a polynucleotide having at least 60% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 7.
In another embodiment, the parent cellobiohydrolase may also be (a) a polypeptide having at least 60% sequence identity to the mature polypeptide of SEQ ID NO: 10; (b) a polypeptide encoded by a polynucleotide that hybridizes under low stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 9 or the full-length complement thereof; or (c) a polypeptide encoded by a polynucleotide having at least 60% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 9.
In another embodiment, the parent cellobiohydrolase may also be (a) a polypeptide having at least 60% sequence identity to the mature polypeptide of SEQ ID NO: 12; (b) a polypeptide encoded by a polynucleotide that hybridizes under low stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 11 or the full-length complement thereof; or (c) a polypeptide encoded by a polynucleotide having at least 60% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 11.
In another embodiment, the parent cellobiohydrolase may also be (a) a polypeptide having at least 60% sequence identity to the mature polypeptide of SEQ ID NO: 14; (b) a polypeptide encoded by a polynucleotide that hybridizes under low stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 13 or the full-length complement thereof; or (c) a polypeptide encoded by a polynucleotide having at least 60% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 13.
In another embodiment, the parent cellobiohydrolase may also be (a) a polypeptide having at least 60% sequence identity to the mature polypeptide of SEQ ID NO: 16; (b) a polypeptide encoded by a polynucleotide that hybridizes under low stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 15 or the full-length complement thereof; or (c) a polypeptide encoded by a polynucleotide having at least 60% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 15.
In another embodiment, the parent cellobiohydrolase may also be (a) a polypeptide having at least 60% sequence identity to the mature polypeptide of SEQ ID NO: 18; (b) a polypeptide encoded by a polynucleotide that hybridizes under low stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 17 or the full-length complement thereof; or (c) a polypeptide encoded by a polynucleotide having at least 60% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 17.
In another embodiment, the parent cellobiohydrolase may also be (a) a polypeptide having at least 60% sequence identity to the mature polypeptide of SEQ ID NO: 20; (b) a polypeptide encoded by a polynucleotide that hybridizes under low stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 19 or the full-length complement thereof; or (c) a polypeptide encoded by a polynucleotide having at least 60% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 19.
In another embodiment, the parent cellobiohydrolase may also be (a) a polypeptide having at least 60% sequence identity to the mature polypeptide of SEQ ID NO: 22; (b) a polypeptide encoded by a polynucleotide that hybridizes under low stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 21 or the full-length complement thereof; or (c) a polypeptide encoded by a polynucleotide having at least 60% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 21.
In one aspect, the parent has a sequence identity to the mature polypeptide of SEQ ID NO: 2 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%, which have cellobiohydrolase activity. In another aspect, the amino acid sequence of the parent differs by up to 10 amino acids, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, from the mature polypeptide of SEQ ID NO: 2.
In another aspect, the parent has a sequence identity to the mature polypeptide of SEQ ID NO: 8 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%, which have cellobiohydrolase activity. In another aspect, the amino acid sequence of the parent differs by up to 10 amino acids, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, from the mature polypeptide of SEQ ID NO: 8.
In another aspect, the parent has a sequence identity to the mature polypeptide of SEQ ID NO: 10 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%, which have cellobiohydrolase activity. In another aspect, the amino acid sequence of the parent differs by up to 10 amino acids, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, from the mature polypeptide of SEQ ID NO: 10.
In another aspect, the parent has a sequence identity to the mature polypeptide of SEQ ID NO: 12 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%, which have cellobiohydrolase activity. In another aspect, the amino acid sequence of the parent differs by up to 10 amino acids, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, from the mature polypeptide of SEQ ID NO: 12.
In another aspect, the parent has a sequence identity to the mature polypeptide of SEQ ID NO: 14 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%, which have cellobiohydrolase activity. In another aspect, the amino acid sequence of the parent differs by up to 10 amino acids, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, from the mature polypeptide of SEQ ID NO: 14.
In another aspect, the parent has a sequence identity to the mature polypeptide of SEQ ID NO: 16 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%, which have cellobiohydrolase activity. In another aspect, the amino acid sequence of the parent differs by up to 10 amino acids, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, from the mature polypeptide of SEQ ID NO: 16.
In another aspect, the parent has a sequence identity to the mature polypeptide of SEQ ID NO: 18 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%, which have cellobiohydrolase activity. In another aspect, the amino acid sequence of the parent differs by up to 10 amino acids, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, from the mature polypeptide of SEQ ID NO: 18.
In another aspect, the parent has a sequence identity to the mature polypeptide of SEQ ID NO: 20 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%, which have cellobiohydrolase activity. In another aspect, the amino acid sequence of the parent differs by up to 10 amino acids, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, from the mature polypeptide of SEQ ID NO: 20.
In another aspect, the parent has a sequence identity to the mature polypeptide of SEQ ID NO: 22 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%, which have cellobiohydrolase activity. In another aspect, the amino acid sequence of the parent differs by up to 10 amino acids, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, from the mature polypeptide of SEQ ID NO: 22.
In another aspect, the parent comprises or consists of the amino acid sequence of SEQ ID NO: 2. In another aspect, the parent comprises or consists of the mature polypeptide of SEQ ID NO: 2. In another aspect, the parent comprises or consists of amino acids 1 to 497 of SEQ ID NO: 2.
In another aspect, the parent comprises or consists of the amino acid sequence of SEQ ID NO: 8. In another aspect, the parent comprises or consists of the mature polypeptide of SEQ ID NO: 8. In another aspect, the parent comprises or consists of amino acids 1 to 506 of SEQ ID NO: 8.
In another aspect, the parent comprises or consists of the amino acid sequence of SEQ ID NO: 10. In another aspect, the parent comprises or consists of the mature polypeptide of SEQ ID NO: 10. In another aspect, the parent comprises or consists of amino acids 1 to 437 of SEQ ID NO: 10.
In another aspect, the parent comprises or consists of the amino acid sequence of SEQ ID NO: 12. In another aspect, the parent comprises or consists of the mature polypeptide of SEQ ID NO: 12. In another aspect, the parent comprises or consists of amino acids 1 to 437 of SEQ ID NO: 12.
In another aspect, the parent comprises or consists of the amino acid sequence of SEQ ID NO: 14. In another aspect, the parent comprises or consists of the mature polypeptide of SEQ ID NO: 14. In another aspect, the parent comprises or consists of amino acids 1 to 507 of SEQ ID NO: 14.
In another aspect, the parent comprises or consists of the amino acid sequence of SEQ ID NO: 16. In another aspect, the parent comprises or consists of the mature polypeptide of SEQ ID NO: 16. In another aspect, the parent comprises or consists of amino acids 1 to 507 of SEQ ID NO: 16.
In another aspect, the parent comprises or consists of the amino acid sequence of SEQ ID NO: 18. In another aspect, the parent comprises or consists of the mature polypeptide of SEQ ID NO: 18. In another aspect, the parent comprises or consists of amino acids 1 to 437 of SEQ ID NO: 18.
In another aspect, the parent comprises or consists of the amino acid sequence of SEQ ID NO: 20. In another aspect, the parent comprises or consists of the mature polypeptide of SEQ ID NO: 20. In another aspect, the parent comprises or consists of amino acids 1 to 430 of SEQ ID NO: 20.
In another aspect, the parent comprises or consists of the amino acid sequence of SEQ ID NO: 22. In another aspect, the parent comprises or consists of the mature polypeptide of SEQ ID NO: 22. In another aspect, the parent comprises or consists of amino acids 1 to 511 of SEQ ID NO: 22.
In another aspect, the parent is a fragment of the mature polypeptide of SEQ ID NO: 2 containing at least 420 amino acid residues, e.g., at least 445 amino acid residues or at least 470 amino acid residues.
In another aspect, the parent is a fragment of the mature polypeptide of SEQ ID NO: 8 containing at 430 amino acid residues, e.g., at least 455 amino acid residues or at least 480 amino acid residues.
In another aspect, the parent is a fragment of the mature polypeptide of SEQ ID NO: 10 containing at least 380 amino acid residues, e.g., at least 400 amino acid residues or at least 420 amino acid residues.
In another aspect, the parent is a fragment of the mature polypeptide of SEQ ID NO: 12 containing at least 380 amino acid residues, e.g., at least 400 amino acid residues or at least 420 amino acid residues.
In another aspect, the parent is a fragment of the mature polypeptide of SEQ ID NO: 14 containing at least 430 amino acid residues, e.g., at least 455 amino acid residues or at least 480 amino acid residues.
In another aspect, the parent is a fragment of the mature polypeptide of SEQ ID NO: 16 containing at least 430 amino acid residues, e.g., at least 455 amino acid residues or at least 480 amino acid residues.
In another aspect, the parent is a fragment of the mature polypeptide of SEQ ID NO: 18 containing at least 380 amino acid residues, e.g., at least 400 amino acid residues or at least 420 amino acid residues.
In another aspect, the parent is a fragment of the mature polypeptide of SEQ ID NO: 20 containing at least 370 amino acid residues, e.g., at least 390 amino acid residues or at least 410 amino acid residues.
In another aspect, the parent is a fragment of the mature polypeptide of SEQ ID NO: 22 containing at least 435 amino acid residues, e.g., at least 460 amino acid residues or at least 485 amino acid residues.
In another aspect, the parent is encoded by a polynucleotide that hybridizes under very low stringency conditions, low stringency conditions, medium stringency conditions, medium-high stringency conditions, high stringency conditions, or very high stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, or SEQ ID NO: 4; or the full-length complement thereof (Sambrook et al., 1989 , Molecular Cloning, A Laboratory Manual, 2d edition, Cold Spring Harbor, New York).
In another aspect, the parent is encoded by a polynucleotide that hybridizes under low stringency conditions, medium stringency conditions, medium-high stringency conditions, high stringency conditions, or very high stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 7; or the full-length complement thereof (Sambrook et al., 1989, supra).
In another aspect, the parent is encoded by a polynucleotide that hybridizes under low stringency conditions, medium stringency conditions, medium-high stringency conditions, high stringency conditions, or very high stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 9; or the full-length complement thereof (Sambrook et al., 1989, supra).
In another aspect, the parent is encoded by a polynucleotide that hybridizes under low stringency conditions, medium stringency conditions, medium-high stringency conditions, high stringency conditions, or very high stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 11; or the full-length complement thereof (Sambrook et al., 1989, supra).
In another aspect, the parent is encoded by a polynucleotide that hybridizes under low stringency conditions, medium stringency conditions, medium-high stringency conditions, high stringency conditions, or very high stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 13; or the full-length complement thereof (Sambrook et al., 1989, supra).
In another aspect, the parent is encoded by a polynucleotide that hybridizes under low stringency conditions, medium stringency conditions, medium-high stringency conditions, high stringency conditions, or very high stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 15; or the full-length complement thereof (Sambrook et al., 1989, supra).
In another aspect, the parent is encoded by a polynucleotide that hybridizes under low stringency conditions, medium stringency conditions, medium-high stringency conditions, high stringency conditions, or very high stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 17; or the full-length complement thereof (Sambrook et al., 1989, supra).
In another aspect, the parent is encoded by a polynucleotide that hybridizes under low stringency conditions, medium stringency conditions, medium-high stringency conditions, high stringency conditions, or very high stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 19; or the full-length complement thereof (Sambrook et al., 1989, supra).
In another aspect, the parent is encoded by a polynucleotide that hybridizes under low stringency conditions, medium stringency conditions, medium-high stringency conditions, high stringency conditions, or very high stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 21; or the full-length complement thereof (Sambrook et al., 1989, supra).
The polynucleotide of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, or SEQ ID NO: 21, or a subsequence thereof, as well as the polypeptide of SEQ ID NO: 2, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 14, SEQ ID NO: 16, SEQ ID NO: 18, SEQ ID NO: 20, or SEQ ID NO: 22, or a fragment thereof, may be used to design nucleic acid probes to identify and clone DNA encoding a parent from strains of different genera or species according to methods well known in the art. In particular, such probes can be used for hybridization with the genomic DNA or cDNA of a cell of interest, following standard Southern blotting procedures, in order to identify and isolate the corresponding gene therein. Such probes can be considerably shorter than the entire sequence, but should be at least 15, e.g., at least 25, at least 35, or at least 70 nucleotides in length. Preferably, the nucleic acid probe is at least 100 nucleotides in length, e.g., at least 200 nucleotides, at least 300 nucleotides, at least 400 nucleotides, at least 500 nucleotides, at least 600 nucleotides, at least 700 nucleotides, at least 800 nucleotides, or at least 900 nucleotides in length. Both DNA and RNA probes can be used. The probes are typically labeled for detecting the corresponding gene (for example, with 32 P, 3 H, 35 S, biotin, or avidin). Such probes are encompassed by the present invention.
A genomic DNA or cDNA library prepared from such other strains may be screened for DNA that hybridizes with the probes described above and encodes a parent. Genomic or other DNA from such other strains may be separated by agarose or polyacrylamide gel electrophoresis, or other separation techniques. DNA from the libraries or the separated DNA may be transferred to and immobilized on nitrocellulose or other suitable carrier material. In order to identify a clone or DNA that hybridizes with SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, or SEQ ID NO: 21, or a subsequence thereof, the carrier material is used in a Southern blot.
For purposes of the present invention, hybridization indicates that the polynucleotide hybridizes to a labeled nucleic acid probe corresponding to (i) SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, or SEQ ID NO: 21; (ii) the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, or SEQ ID NO: 21; (iii) the full-length complement thereof; or (iv) a subsequence thereof; under very low to very high stringency conditions. Molecules to which the nucleic acid probe hybridizes under these conditions can be detected using, for example, X-ray film or any other detection means known in the art.
In one aspect, the nucleic acid probe is the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, or SEQ ID NO: 21. In another aspect, the nucleic acid probe is nucleotides 52 to 1673 of SEQ ID NO: 1, nucleotides 52 to 1542 of SEQ ID NO: 3, nucleotides 52 to 1542 of SEQ ID NO: 4, nucleotides 79 to 1596 of SEQ ID NO: 7, nucleotides 52 to 1371 of SEQ ID NO: 9, nucleotides 55 to 1482 of SEQ ID NO: 11, nucleotides 76 to 1596 of SEQ ID NO: 13, nucleotides 76 to 1596 of SEQ ID NO: 15, nucleotides 55 to 1504 of SEQ ID NO: 17, nucleotides 61 to 1350 of SEQ ID NO: 19, or nucleotides 55 to 1587 of SEQ ID NO: 21. In another aspect, the nucleic acid probe is a polynucleotide that encodes the polypeptide of SEQ ID NO: 2, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 14, SEQ ID NO: 16, SEQ ID NO: 18, SEQ ID NO: 20, or SEQ ID NO: 22; the mature polypeptide thereof; or a fragment thereof. In another aspect, the nucleic acid probe is SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, or SEQ ID NO: 21.
In another aspect, the parent is encoded by a polynucleotide having a sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, or SEQ ID NO: 4 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
In another aspect, the parent is encoded by a polynucleotide having a sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 7 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
In another aspect, the parent is encoded by a polynucleotide having a sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 9 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
In another aspect, the parent is encoded by a polynucleotide having a sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 11 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
In another aspect, the parent is encoded by a polynucleotide having a sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 13 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
In another aspect, the parent is encoded by a polynucleotide having a sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 15 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
In another aspect, the parent is encoded by a polynucleotide having a sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 17 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
In another aspect, the parent is encoded by a polynucleotide having a sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 19 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
In another aspect, the parent is encoded by a polynucleotide having a sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 21 of at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%.
In another embodiment, the parent is an allelic variant of the mature polypeptide of SEQ ID NO: 2, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 14, SEQ ID NO: 16, SEQ ID NO: 18, SEQ ID NO: 20, or SEQ ID NO: 22.
The parent may also be a hybrid or chimeric polypeptide in which a region of parent is replaced with a region of another polypeptide. In one aspect, the region is a carbohydrate binding domain. The carbohydrate binding domain of a parent may be replaced with another (heterologous) carbohydrate binding domain.
The parent may also be a fusion polypeptide or cleavable fusion polypeptide in which another polypeptide is fused at the N-terminus or the C-terminus of the parent. In one aspect, the other polypeptide is a carbohydrate binding domain. The catalytic domain of a parent without a carbohydrate binding domain may be fused to a carbohydrate binding domain. A fusion polypeptide is produced by fusing a polynucleotide encoding another polypeptide to a polynucleotide encoding a parent. Techniques for producing fusion polypeptides are described supra. A fusion polypeptide can further comprise a cleavage site between the two polypeptides as described supra.
In one embodiment, the parent is a hybrid polypeptide in which the carbohydrate binding domain of the parent is replaced with a different carbohydrate binding domain. In another embodiment, the parent is a fusion protein in which a heterologous carbohydrate binding domain is fused to the parent without a carbohydrate binding domain. In one aspect, the carbohydrate binding domain is fused to the N-terminus of the parent. In another aspect, the carbohydrate binding domain is fused to the C-terminus of the parent. In another aspect, the fusion protein comprises or consists of SEQ ID NO: 73 or the mature polypeptide thereof. The polynucleotide of SEQ ID NO: 72 encodes the polypeptide of SEQ ID NO: 73.
The parent may be obtained from microorganisms of any genus. For purposes of the present invention, the term “obtained from” as used herein in connection with a given source shall mean that the parent encoded by a polynucleotide is produced by the source or by a strain in which the polynucleotide from the source has been inserted. In one aspect, the parent is secreted extracellularly.
The parent may be a filamentous fungal cellobiohydrolase. For example, the parent may be a filamentous fungal cellobiohydrolase such as an Aspergillus, Chaetomium, Chrysosporium, Myceliophthora, Penicillium, Talaromyces, Thermoascus , or Trichoderma cellobiohydrolase.
In one aspect, the parent is an Aspergillus aculeatus, Aspergillus awamori, Aspergillus foetidus, Aspergillus fumigatus, Aspergillus japonicus, Aspergillus nidulans, Aspergillus niger, Aspergillus oryzae, Chaetomium thermophilum, Chrysosporium inops, Chrysosporium keratinophilum, Chrysosporium lucknowense, Chrysosporium merdarium, Chrysosporium pannicola, Chrysosporium queenslandicum, Chrysosporium tropicum, Chrysosporium zonatum, Myceliophthora thermophila, Penicillium emersonii, Penicillium funiculosum, Penicillium purpurogenum, Talaromyces byssochlamydoides, Talaromyces emersonii, Talaromyces leycettanus, Trichoderma harzianum, Trichoderma koningii, Trichoderma longibrachiaturn, Trichoderma reesei , or Trichoderma viride cellobiohydrolase.
In another aspect, the parent is a Trichoderma reesei cellobiohydrolase, e.g., the cellobiohydrolase of SEQ ID NO: 2 or the mature polypeptide thereof.
In another aspect, the parent is an Aspergillus fumigatus cellobiohydrolase, e.g., the cellobiohydrolase of SEQ ID NO: 8 or the mature polypeptide thereof.
In another aspect, the parent is a Thermoascus aurantiacus cellobiohydrolase, e.g., the cellobiohydrolase of SEQ ID NO: 10 or the mature polypeptide thereof.
In another aspect, the parent is a Penicillium emersonii ( Rasamsonia emersonii ) cellobiohydrolase, e.g., the cellobiohydrolase of SEQ ID NO: 12 or the mature polypeptide thereof.
In another aspect, the parent is a Talaromyces leycettanus cellobiohydrolase, e.g., the cellobiohydrolase of SEQ ID NO: 14 or the mature polypeptide thereof.
In another aspect, the parent is another Talaromyces leycettanus cellobiohydrolase, e.g., the cellobiohydrolase of SEQ ID NO: 16 or the mature polypeptide thereof. In another aspect, the parent is a Talaromyces byssochlamydoides cellobiohydrolase, e.g., the cellobiohydrolase of SEQ ID NO: 18 or the mature polypeptide thereof.
In another aspect, the parent is another Myceliophthora thermophila cellobiohydrolase, e.g., the cellobiohydrolase of SEQ ID NO: 20 or the mature polypeptide thereof.
In another aspect, the parent is another Chaetomium thermophilum cellobiohydrolase, e.g., the cellobiohydrolase of SEQ ID NO: 22 or the mature polypeptide thereof.
It will be understood that for the aforementioned species, the invention encompasses both the perfect and imperfect states, and other taxonomic equivalents, e.g., anamorphs, regardless of the species name by which they are known. Those skilled in the art will readily recognize the identity of appropriate equivalents.
Strains of these species are readily accessible to the public in a number of culture collections, such as the American Type Culture Collection (ATCC), Deutsche Sammlung von Mikroorganismen and Zellkulturen GmbH (DSMZ), Centraalbureau Voor Schimmelcultures (CBS), and Agricultural Research Service Patent Culture Collection, Northern Regional Research Center (NRRL).
The parent may be identified and obtained from other sources including microorganisms isolated from nature (e.g., soil, composts, water, etc.) or DNA samples obtained directly from natural materials (e.g., soil, composts, water, etc.) using the above-mentioned probes. Techniques for isolating microorganisms and DNA directly from natural habitats are well known in the art. A polynucleotide encoding a parent may then be obtained by similarly screening a genomic DNA or cDNA library of another microorganism or mixed DNA sample. Once a polynucleotide encoding a parent has been detected with the probe(s), the polynucleotide can be isolated or cloned by utilizing techniques that are known to those of ordinary skill in the art (see, e.g., Sambrook et al., 1989, supra).
Preparation of Variants
The present invention also relates to methods for obtaining a cellobiohydrolase variant, comprising: (a) introducing into a parent cellobiohydrolase deletions at two or more consecutive positions of the B2-loop, wherein the variant has cellobiohydrolase activity; and optionally (b) recovering the variant.
The present invention also relates to methods for obtaining a cellobiohydrolase variant, comprising: (a) introducing into a parent cellobiohydrolase a deletion at one or more positions corresponding to positions 195, 196, 197, and 198 of SEQ ID NO: 2, wherein the variant has cellobiohydrolase activity; and optionally (b) recovering the variant.
The variants can be prepared using any mutagenesis procedure known in the art, such as site-directed mutagenesis, synthetic gene construction, semi-synthetic gene construction, random mutagenesis, shuffling, etc.
Site-directed mutagenesis is a technique in which one or more (e.g., several) mutations are introduced at one or more defined sites in a polynucleotide encoding the parent. Any site-directed mutagenesis procedure can be used in the present invention. There are many commercial kits available that can be used to prepare variants.
Site-directed mutagenesis can be accomplished in vitro by PCR involving the use of oligonucleotide primers containing the desired mutation. Site-directed mutagenesis can also be performed in vitro by cassette mutagenesis involving the cleavage by a restriction enzyme at a site in the plasmid comprising a polynucleotide encoding the parent and subsequent ligation of an oligonucleotide containing the mutation in the polynucleotide. Usually the restriction enzyme that digests the plasmid and the oligonucleotide is the same, permitting sticky ends of the plasmid and the insert to ligate to one another. See, e.g., Scherer and Davis, 1979 , Proc. Natl. Acad. Sci. USA 76: 4949-4955; and Barton et al., 1990 , Nucleic Acids Res. 18: 7349-4966.
Site-directed mutagenesis can also be accomplished in vivo by methods known in the art. See, e.g., U.S. Patent Application Publication No. 2004/0171154; Storici et al., 2001 , Nature Biotechnol. 19: 773-776; Kren et al., 1998 , Nat. Med. 4: 285-290; and Calissano and Macino, 1996 , Fungal Genet. Newslett. 43: 15-16.
Site-saturation mutagenesis systematically replaces a polypeptide coding sequence with sequences encoding all 19 amino acids at one or more (e.g., several) specific positions (Parikh and Matsumura, 2005 , J. Mol. Biol. 352: 621-628).
Synthetic gene construction entails in vitro synthesis of a designed polynucleotide molecule to encode a polypeptide of interest. Gene synthesis can be performed utilizing a number of techniques, such as the multiplex microchip-based technology described by Tian et al. (2004 , Nature 432: 1050-1054) and similar technologies wherein oligonucleotides are synthesized and assembled upon photo-programmable microfluidic chips.
Single or multiple amino acid substitutions, deletions, and/or insertions can be made and tested using known methods of mutagenesis, recombination, and/or shuffling, followed by a relevant screening procedure, such as those disclosed by Reidhaar-Olson and Sauer, 1988 , Science 241: 53-57; Bowie and Sauer, 1989 , Proc. Natl. Acad. Sci. USA 86: 2152-2156; WO 95/17413; or WO 95/22625. Other methods that can be used include error-prone PCR, phage display (e.g., Lowman et al., 1991 , Biochemistry 30: 10832-10837; U.S. Pat. No. 5,223,409; WO 92/06204) and region-directed mutagenesis (Derbyshire et al., 1986 , Gene 46: 145; Ner et al., 1988 , DNA 7: 127).
Mutagenesis/shuffling methods can be combined with high-throughput, automated screening methods to detect activity of cloned, mutagenized polypeptides expressed by host cells (Ness et al., 1999 , Nature Biotechnology 17: 893-896). Mutagenized DNA molecules that encode active polypeptides can be recovered from the host cells and rapidly sequenced using standard methods in the art. These methods allow the rapid determination of the importance of individual amino acid residues in a polypeptide.
Semi-synthetic gene construction is accomplished by combining aspects of synthetic gene construction, and/or site-directed mutagenesis, and/or random mutagenesis, and/or shuffling. Semi-synthetic construction is typified by a process utilizing polynucleotide fragments that are synthesized, in combination with PCR techniques. Defined regions of genes may thus be synthesized de novo, while other regions may be amplified using site-specific mutagenic primers, while yet other regions may be subjected to error-prone PCR or non-error prone PCR amplification. Polynucleotide subsequences may then be shuffled.
Polynucleotides
The present invention also relates to isolated polynucleotides encoding a variant of the present invention.
Nucleic Acid Constructs
The present invention also relates to nucleic acid constructs comprising a polynucleotide encoding a variant of the present invention operably linked to one or more control sequences that direct the expression of the coding sequence in a suitable host cell under conditions compatible with the control sequences.
The polynucleotide may be manipulated in a variety of ways to provide for expression of a variant. Manipulation of the polynucleotide prior to its insertion into a vector may be desirable or necessary depending on the expression vector. The techniques for modifying polynucleotides utilizing recombinant DNA methods are well known in the art.
The control sequence may be a promoter, a polynucleotide recognized by a host cell for expression of a polynucleotide encoding a variant of the present invention. The promoter contains transcriptional control sequences that mediate the expression of the variant. The promoter may be any polynucleotide that shows transcriptional activity in the host cell including mutant, truncated, and hybrid promoters, and may be obtained from genes encoding extracellular or intracellular polypeptides either homologous or heterologous to the host cell.
Examples of suitable promoters for directing transcription of the nucleic acid constructs of the present invention in a bacterial host cell are the promoters obtained from the Bacillus amyloliquefaciens alpha-amylase gene (amyQ), Bacillus licheniformis alpha-amylase gene (amyL), Bacillus licheniformis penicillinase gene (penP), Bacillus stearothermophilus maltogenic amylase gene (amyM), Bacillus subtilis levansucrase gene (sacB), Bacillus subtilis xylA and xylB genes, Bacillus thuringiensis cryIIIA gene (Agaisse and Lereclus, 1994 , Molecular Microbiology 13: 97-107), E. coli lac operon, E. coli trc promoter (Egon et al., 1988 , Gene 69: 301-315), Streptomyces coelicolor agarase gene (dagA), and prokaryotic beta-lactamase gene (Villa-Kamaroff et al., 1978 , Proc. Natl. Acad. Sci. USA 75: 3727-3731), as well as the tac promoter (DeBoer et al., 1983 , Proc. Natl. Acad. Sci. USA 80: 21-25). Further promoters are described in “Useful proteins from recombinant bacteria” in Gilbert et al., 1980 , Scientific American 242: 74-94; and in Sambrook et al., 1989, supra. Examples of tandem promoters are disclosed in WO 99/43835.
Examples of suitable promoters for directing transcription of the nucleic acid constructs of the present invention in a filamentous fungal host cell are promoters obtained from the genes for Aspergillus nidulans acetamidase, Aspergillus niger neutral alpha-amylase, Aspergillus niger acid stable alpha-amylase, Aspergillus niger or Aspergillus awamori glucoamylase (glaA), Aspergillus oryzae TAKA amylase, Aspergillus oryzae alkaline protease, Aspergillus oryzae triose phosphate isomerase, Fusarium oxysporum trypsin-like protease (WO 96/00787), Fusarium venenatum amyloglucosidase (WO 00/56900), Fusarium venenatum Daria (WO 00/56900), Fusarium venenatum Quinn (WO 00/56900), Rhizomucor miehei lipase, Rhizomucor miehei aspartic proteinase, Trichoderma reesei beta-glucosidase, Trichoderma reesei cellobiohydrolase I, Trichoderma reesei cellobiohydrolase II, Trichoderma reesei endoglucanase I, Trichoderma reesei endoglucanase II, Trichoderma reesei endoglucanase III, Trichoderma reesei endoglucanase V, Trichoderma reesei xylanase I, Trichoderma reesei xylanase II, Trichoderma reesei xylanase III, Trichoderma reesei beta-xylosidase, and Trichoderma reesei translation elongation factor, as well as the NA2-tpi promoter (a modified promoter from an Aspergillus neutral alpha-amylase gene in which the untranslated leader has been replaced by an untranslated leader from an Aspergillus triose phosphate isomerase gene; non-limiting examples include modified promoters from an Aspergillus niger neutral alpha-amylase gene in which the untranslated leader has been replaced by an untranslated leader from an Aspergillus nidulans or Aspergillus oryzae triose phosphate isomerase gene); and mutant, truncated, and hybrid promoters thereof. Other promoters are described in U.S. Pat. No. 6,011,147.
In a yeast host, useful promoters are obtained from the genes for Saccharomyces cerevisiae enolase (ENO-1), Saccharomyces cerevisiae galactokinase (GAL1), Saccharomyces cerevisiae alcohol dehydrogenase/glyceraldehyde-3-phosphate dehydrogenase (ADH1, ADH2/GAP), Saccharomyces cerevisiae triose phosphate isomerase (TPI), Saccharomyces cerevisiae metallothionein (CUP1), and Saccharomyces cerevisiae 3-phosphoglycerate kinase. Other useful promoters for yeast host cells are described by Romanos et al., 1992 , Yeast 8: 423-488.
The control sequence may also be a transcription terminator, which is recognized by a host cell to terminate transcription. The terminator is operably linked to the 3′-terminus of the polynucleotide encoding the variant. Any terminator that is functional in the host cell may be used in the present invention.
Preferred terminators for bacterial host cells are obtained from the genes for Bacillus clausii alkaline protease (aprH), Bacillus licheniformis alpha-amylase (amyL), and Escherichia coli ribosomal RNA (rrnB).
Preferred terminators for filamentous fungal host cells are obtained from the genes for Aspergillus nidulans acetamidase, Aspergillus nidulans anthranilate synthase, Aspergillus niger glucoamylase, Aspergillus niger alpha-glucosidase, Aspergillus oryzae TAKA amylase, Fusarium oxysporum trypsin-like protease, Trichoderma reesei beta-glucosidase, Trichoderma reesei cellobiohydrolase I, Trichoderma reesei cellobiohydrolase II, Trichoderma reesei endoglucanase I, Trichoderma reesei endoglucanase II, Trichoderma reesei endoglucanase III, Trichoderma reesei endoglucanase V, Trichoderma reesei xylanase I, Trichoderma reesei xylanase II, Trichoderma reesei xylanase III, Trichoderma reesei beta-xylosidase, and Trichoderma reesei translation elongation factor.
Preferred terminators for yeast host cells are obtained from the genes for Saccharomyces cerevisiae enolase, Saccharomyces cerevisiae cytochrome C (CYC1), and Saccharomyces cerevisiae glyceraldehyde-3-phosphate dehydrogenase. Other useful terminators for yeast host cells are described by Romanos et al., 1992, supra.
The control sequence may also be an mRNA stabilizer region downstream of a promoter and upstream of the coding sequence of a gene which increases expression of the gene.
Examples of suitable mRNA stabilizer regions are obtained from a Bacillus thuringiensis cryIIIA gene (WO 94/25612) and a Bacillus subtilis SP82 gene (Hue et al., 1995 , Journal of Bacteriology 177: 3465-3471).
The control sequence may also be a leader, a nontranslated region of an mRNA that is important for translation by the host cell. The leader is operably linked to the 5′-terminus of the polynucleotide encoding the variant. Any leader that is functional in the host cell may be used.
Preferred leaders for filamentous fungal host cells are obtained from the genes for Aspergillus oryzae TAKA amylase and Aspergillus nidulans triose phosphate isomerase.
Suitable leaders for yeast host cells are obtained from the genes for Saccharomyces cerevisiae enolase (ENO-1), Saccharomyces cerevisiae 3-phosphoglycerate kinase, Saccharomyces cerevisiae alpha-factor, and Saccharomyces cerevisiae alcohol dehydrogenase/glyceraldehyde-3-phosphate dehydrogenase (ADH2/GAP).
The control sequence may also be a polyadenylation sequence, a sequence operably linked to the 3′-terminus of the polynucleotide and, when transcribed, is recognized by the host cell as a signal to add polyadenosine residues to transcribed mRNA. Any polyadenylation sequence that is functional in the host cell may be used.
Preferred polyadenylation sequences for filamentous fungal host cells are obtained from the genes for Aspergillus nidulans anthranilate synthase, Aspergillus niger glucoamylase, Aspergillus niger alpha-glucosidase Aspergillus oryzae TAKA amylase, and Fusarium oxysporum trypsin-like protease.
Useful polyadenylation sequences for yeast host cells are described by Guo and Sherman, 1995 , Mol. Cellular Biol. 15: 5983-5990.
The control sequence may also be a signal peptide coding region that encodes a signal peptide linked to the N-terminus of a variant and directs the variant into the cell's secretory pathway. The 5′-end of the coding sequence of the polynucleotide may inherently contain a signal peptide coding sequence naturally linked in translation reading frame with the segment of the coding sequence that encodes the variant. Alternatively, the 5′-end of the coding sequence may contain a signal peptide coding sequence that is foreign to the coding sequence. A foreign signal peptide coding sequence may be required where the coding sequence does not naturally contain a signal peptide coding sequence. Alternatively, a foreign signal peptide coding sequence may simply replace the natural signal peptide coding sequence in order to enhance secretion of the variant. However, any signal peptide coding sequence that directs the expressed variant into the secretory pathway of a host cell may be used.
Effective signal peptide coding sequences for bacterial host cells are the signal peptide coding sequences obtained from the genes for Bacillus NCIB 11837 maltogenic amylase, Bacillus licheniformis subtilisin, Bacillus licheniformis beta-lactamase, Bacillus stearothermophilus alpha-amylase, Bacillus stearothermophilus neutral proteases (nprT, nprS, nprM), and Bacillus subtilis prsA. Further signal peptides are described by Simonen and Palva, 1993 , Microbiological Reviews 57: 109-137.
Effective signal peptide coding sequences for filamentous fungal host cells are the signal peptide coding sequences obtained from the genes for Aspergillus niger neutral amylase, Aspergillus niger glucoamylase, Aspergillus oryzae TAKA amylase, Humicola insolens cellulase, Humicola insolens endoglucanase V, Humicola lanuginosa lipase, and Rhizomucor miehei aspartic proteinase.
Useful signal peptides for yeast host cells are obtained from the genes for Saccharomyces cerevisiae alpha-factor and Saccharomyces cerevisiae invertase. Other useful signal peptide coding sequences are described by Romanos et al., 1992, supra.
The control sequence may also be a propeptide coding sequence that encodes a propeptide positioned at the N-terminus of a variant. The resultant polypeptide is known as a proenzyme or propolypeptide (or a zymogen in some cases). A propolypeptide is generally inactive and can be converted to an active variant by catalytic or autocatalytic cleavage of the propeptide from the propolypeptide. The propeptide coding sequence may be obtained from the genes for Bacillus subtilis alkaline protease (aprE), Bacillus subtilis neutral protease (nprT), Myceliophthora thermophila laccase (WO 95/33836), Rhizomucor miehei aspartic proteinase, and Saccharomyces cerevisiae alpha-factor.
Where both signal peptide and propeptide sequences are present, the propeptide sequence is positioned next to the N-terminus of a variant and the signal peptide sequence is positioned next to the N-terminus of the propeptide sequence.
It may also be desirable to add regulatory sequences that regulate expression of the variant relative to the growth of the host cell. Examples of regulatory sequences are those that cause expression of the gene to be turned on or off in response to a chemical or physical stimulus, including the presence of a regulatory compound. Regulatory sequences in prokaryotic systems include the lac, tac, and trp operator systems. In yeast, the ADH2 system or GAL1 system may be used. In filamentous fungi, the Aspergillus niger glucoamylase promoter, Aspergillus oryzae TAKA alpha-amylase promoter, and Aspergillus oryzae glucoamylase promoter, Trichoderma reesei cellobiohydrolase I promoter, and Trichoderma reesei cellobiohydrolase II promoter may be used. Other examples of regulatory sequences are those that allow for gene amplification. In eukaryotic systems, these regulatory sequences include the dihydrofolate reductase gene that is amplified in the presence of methotrexate, and the metallothionein genes that are amplified with heavy metals. In these cases, the polynucleotide encoding the variant would be operably linked to the regulatory sequence.
Expression Vectors
The present invention also relates to recombinant expression vectors comprising a polynucleotide encoding a variant of the present invention, a promoter, and transcriptional and translational stop signals. The various nucleotide and control sequences may be joined together to produce a recombinant expression vector that may include one or more convenient restriction sites to allow for insertion or substitution of the polynucleotide encoding the variant at such sites. Alternatively, the polynucleotide may be expressed by inserting the polynucleotide or a nucleic acid construct comprising the polynucleotide into an appropriate vector for expression. In creating the expression vector, the coding sequence is located in the vector so that the coding sequence is operably linked with the appropriate control sequences for expression.
The recombinant expression vector may be any vector (e.g., a plasmid or virus) that can be conveniently subjected to recombinant DNA procedures and can bring about expression of the polynucleotide. The choice of the vector will typically depend on the compatibility of the vector with the host cell into which the vector is to be introduced. The vector may be a linear or closed circular plasmid.
The vector may be an autonomously replicating vector, i.e., a vector that exists as an extrachromosomal entity, the replication of which is independent of chromosomal replication, e.g., a plasmid, an extrachromosomal element, a minichromosome, or an artificial chromosome. The vector may contain any means for assuring self-replication. Alternatively, the vector may be one that, when introduced into the host cell, is integrated into the genome and replicated together with the chromosome(s) into which it has been integrated. Furthermore, a single vector or plasmid or two or more vectors or plasmids that together contain the total DNA to be introduced into the genome of the host cell, or a transposon, may be used.
The vector preferably contains one or more selectable markers that permit easy selection of transformed, transfected, transduced, or the like cells. A selectable marker is a gene the product of which provides for biocide or viral resistance, resistance to heavy metals, prototrophy to auxotrophs, and the like.
Examples of bacterial selectable markers are Bacillus licheniformis or Bacillus subtilis dal genes, or markers that confer antibiotic resistance such as ampicillin, chloramphenicol, kanamycin, neomycin, spectinomycin, or tetracycline resistance. Suitable markers for yeast host cells include, but are not limited to, ADE2, HIS3, LEU2, LYS2, MET3, TRP1, and URA3. Selectable markers for use in a filamentous fungal host cell include, but are not limited to, adeA (phosphoribosylaminoimidazole-succinocarboxamide synthase), adeB (phosphoribosyl-aminoimidazole synthase), amdS (acetamidase), argB (ornithine carbamoyltransferase), bar (phosphinothricin acetyltransferase), hph (hygromycin phosphotransferase), niaD (nitrate reductase), pyrG (orotidine-5′-phosphate decarboxylase), sC (sulfate adenyltransferase), and trpC (anthranilate synthase), as well as equivalents thereof. Preferred for use in an Aspergillus cell are Aspergillus nidulans or Aspergillus oryzae amdS and pyrG genes and a Streptomyces hygroscopicus bar gene. Preferred for use in a Trichoderma cell are adeA, adeB, amdS, hph, and pyrG genes.
The selectable marker may be a dual selectable marker system as described in WO 2010/039889. In one aspect, the dual selectable marker is a hph-tk dual selectable marker system.
The vector preferably contains an element(s) that permits integration of the vector into the host cell's genome or autonomous replication of the vector in the cell independent of the genome.
For integration into the host cell genome, the vector may rely on the polynucleotide's sequence encoding the variant or any other element of the vector for integration into the genome by homologous or non-homologous recombination. Alternatively, the vector may contain additional polynucleotides for directing integration by homologous recombination into the genome of the host cell at a precise location(s) in the chromosome(s). To increase the likelihood of integration at a precise location, the integrational elements should contain a sufficient number of nucleic acids, such as 100 to 10,000 base pairs, 400 to 10,000 base pairs, and 800 to 10,000 base pairs, which have a high degree of sequence identity to the corresponding target sequence to enhance the probability of homologous recombination. The integrational elements may be any sequence that is homologous with the target sequence in the genome of the host cell. Furthermore, the integrational elements may be non-encoding or encoding polynucleotides. On the other hand, the vector may be integrated into the genome of the host cell by non-homologous recombination.
For autonomous replication, the vector may further comprise an origin of replication enabling the vector to replicate autonomously in the host cell in question. The origin of replication may be any plasmid replicator mediating autonomous replication that functions in a cell. The term “origin of replication” or “plasmid replicator” means a polynucleotide that enables a plasmid or vector to replicate in vivo.
Examples of bacterial origins of replication are the origins of replication of plasmids pBR322, pUC19, pACYC177, and pACYC184 permitting replication in E. coli , and pUB110, pE194, pTA1060, and pAMR1 permitting replication in Bacillus.
Examples of origins of replication for use in a yeast host cell are the 2 micron origin of replication, ARS1, ARS4, the combination of ARS1 and CEN3, and the combination of ARS4 and CEN6.
Examples of origins of replication useful in a filamentous fungal cell are AMA1 and ANS1 (Gems et al., 1991 , Gene 98: 61-67; Cullen et al., 1987 , Nucleic Acids Res. 15: 9163-9175; WO 00/24883). Isolation of the AMA1 gene and construction of plasmids or vectors comprising the gene can be accomplished according to the methods disclosed in WO 00/24883.
More than one copy of a polynucleotide of the present invention may be inserted into a host cell to increase production of a variant. An increase in the copy number of the polynucleotide can be obtained by integrating at least one additional copy of the sequence into the host cell genome or by including an amplifiable selectable marker gene with the polynucleotide where cells containing amplified copies of the selectable marker gene, and thereby additional copies of the polynucleotide, can be selected for by cultivating the cells in the presence of the appropriate selectable agent.
The procedures used to ligate the elements described above to construct the recombinant expression vectors of the present invention are well known to one skilled in the art (see, e.g., Sambrook et al., 1989, supra).
Host Cells
The present invention also relates to recombinant host cells, comprising a polynucleotide encoding a variant of the present invention operably linked to one or more control sequences that direct the production of a variant of the present invention. A construct or vector comprising a polynucleotide is introduced into a host cell so that the construct or vector is maintained as a chromosomal integrant or as a self-replicating extra-chromosomal vector as described earlier. The term “host cell” encompasses any progeny of a parent cell that is not identical to the parent cell due to mutations that occur during replication. The choice of a host cell will to a large extent depend upon the gene encoding the variant and its source.
The host cell may be any cell useful in the recombinant production of a variant, e.g., a prokaryote or a eukaryote.
The prokaryotic host cell may be any Gram-positive or Gram-negative bacterium. Gram-positive bacteria include, but are not limited to, Bacillus, Clostridium, Enterococcus, Geobacillus, Lactobacillus, Lactococcus, Oceanobacillus, Staphylococcus, Streptococcus , and Streptomyces . Gram-negative bacteria include, but are not limited to, Campylobacter, E. coli, Flavobacterium, Fusobacterium, Helicobacter, Ilyobacter, Neisseria, Pseudomonas, Salmonella , and Ureaplasma.
The bacterial host cell may be any Bacillus cell including, but not limited to, Bacillus alkalophilus, Bacillus amyloliquefaciens, Bacillus brevis, Bacillus circulans, Bacillus clausii, Bacillus coagulans, Bacillus firmus, Bacillus lautus, Bacillus lentus, Bacillus licheniformis, Bacillus megaterium, Bacillus pumilus, Bacillus stearothermophilus, Bacillus subtilis , and Bacillus thuringiensis cells.
The bacterial host cell may also be any Streptococcus cell including, but not limited to, Streptococcus equisimilis, Streptococcus pyogenes, Streptococcus uberis , and Streptococcus equi subsp. Zooepidemicus cells.
The bacterial host cell may also be any Streptomyces cell, including, but not limited to, Streptomyces achromogenes, Streptomyces avermitilis, Streptomyces coelicolor, Streptomyces griseus , and Streptomyces lividans cells.
The introduction of DNA into a Bacillus cell may be effected by protoplast transformation (see, e.g., Chang and Cohen, 1979 , Mol. Gen. Genet. 168: 111-115), competent cell transformation (see, e.g., Young and Spizizen, 1961 , J. Bacteriol. 81: 823-829, or Dubnau and Davidoff-Abelson, 1971 , J. Mol. Biol. 56: 209-221), electroporation (see, e.g., Shigekawa and Dower, 1988 , Biotechniques 6: 742-751), or conjugation (see, e.g., Koehler and Thorne, 1987 , J. Bacteriol. 169: 5271-5278). The introduction of DNA into an E. coli cell may be effected by protoplast transformation (see, e.g., Hanahan, 1983 , J. Mol. Biol. 166: 557-580) or electroporation (see, e.g., Dower et al., 1988 , Nucleic Acids Res. 16: 6127-6145). The introduction of DNA into a Streptomyces cell may be effected by protoplast transformation, electroporation (see, e.g., Gong et al., 2004 , Folia Microbiol . ( Praha ) 49: 399-405), conjugation (see, e.g., Mazodier et al., 1989 , J. Bacteriol. 171: 3583-3585), or transduction (see, e.g., Burke et al., 2001 , Proc. Natl. Acad. Sci. USA 98: 6289-6294). The introduction of DNA into a Pseudomonas cell may be effected by electroporation (see, e.g., Choi et al., 2006 , J. Microbiol. Methods 64: 391-397), or conjugation (see, e.g., Pinedo and Smets, 2005 , Appl. Environ. Microbiol. 71: 51-57). The introduction of DNA into a Streptococcus cell may be effected by natural competence (see, e.g., Perry and Kuramitsu, 1981 , Infect. Immun. 32: 1295-1297), protoplast transformation (see, e.g., Catt and Jollick, 1991 , Microbios 68: 189-207), electroporation (see, e.g., Buckley et al., 1999 , Appl. Environ. Microbiol. 65: 3800-3804), or conjugation (see, e.g., Clewell, 1981 , Microbiol. Rev. 45: 409-436). However, any method known in the art for introducing DNA into a host cell can be used.
The host cell may also be a eukaryote, such as a mammalian, insect, plant, or fungal cell.
The host cell may be a fungal cell. “Fungi” as used herein includes the phyla Ascomycota, Basidiomycota, Chytridiomycota, and Zygomycota as well as the Oomycota and all mitosporic fungi (as defined by Hawksworth et al., In, Ainsworth and Bisby's Dictionary of The Fungi, 8th edition, 1995, CAB International, University Press, Cambridge, UK).
The fungal host cell may be a yeast cell. “Yeast” as used herein includes ascosporogenous yeast (Endomycetales), basidiosporogenous yeast, and yeast belonging to the Fungi Imperfecti (Blastomycetes). Since the classification of yeast may change in the future, for the purposes of this invention, yeast shall be defined as described in Biology and Activities of Yeast (Skinner, Passmore, and Davenport, editors, Soc. App. Bacteriol. Symposium Series No. 9, 1980).
The yeast host cell may be a Candida, Hansenula, Kluyveromyces, Pichia, Saccharomyces, Schizosaccharomyces , or Yarrowia cell such as a Kluyveromyces lactis, Saccharomyces carlsbergensis, Saccharomyces cerevisiae, Saccharomyces diastaticus, Saccharomyces douglasii, Saccharomyces kluyveri, Saccharomyces norbensis, Saccharomyces oviformis , or Yarrowia lipolytica cell.
The fungal host cell may be a filamentous fungal cell. “Filamentous fungi” include all filamentous forms of the subdivision Eumycota and Oomycota (as defined by Hawksworth et al., 1995, supra). The filamentous fungi are generally characterized by a mycelial wall composed of chitin, cellulose, glucan, chitosan, mannan, and other complex polysaccharides. Vegetative growth is by hyphal elongation and carbon catabolism is obligately aerobic. In contrast, vegetative growth by yeasts such as Saccharomyces cerevisiae is by budding of a unicellular thallus and carbon catabolism may be fermentative.
The filamentous fungal host cell may be an Acremonium, Aspergillus, Aureobasidium, Bjerkandera, Ceriporiopsis, Chrysosporium, Coprinus, Coriolus, Cryptococcus, Filibasidium, Fusarium, Humicola, Magnaporthe, Mucor, Myceliophthora, Neocallimastix, Neurospora, Paecilomyces, Penicillium, Phanerochaete, Phlebia, Piromyces, Pleurotus, Schizophyllum, Talaromyces, Thermoascus, Thielavia, Tolypocladium, Trametes , or Trichoderma cell.
For example, the filamentous fungal host cell may be an Aspergillus awamori, Aspergillus foetidus, Aspergillus fumigatus, Aspergillus japonicus, Aspergillus nidulans, Aspergillus niger, Aspergillus oryzae, Bjerkandera adusta, Ceriporiopsis aneirina, Ceriporiopsis caregiea, Ceriporiopsis gilvescens, Ceriporiopsis pannocinta, Ceriporiopsis rivulosa, Ceriporiopsis subrufa, Ceriporiopsis subvermispora, Chrysosporium inops, Chrysosporium keratinophilum, Chrysosporium lucknowense, Chrysosporium merdarium, Chrysosporium pannicola, Chrysosporium queenslandicum, Chrysosporium tropicum, Chrysosporium zonatum, Coprinus cinereus, Coriolus hirsutus, Fusarium bactridioides, Fusarium cerealis, Fusarium crookwellense, Fusarium culmorum, Fusarium graminearum, Fusarium graminum, Fusarium heterosporum, Fusarium negundi, Fusarium oxysporum, Fusarium reticulatum, Fusarium roseum, Fusarium sambucinum, Fusarium sarcochroum, Fusarium sporotrichioides, Fusarium sulphureum, Fusarium torulosum, Fusarium trichothecioides, Fusarium venenatum, Humicola insolens, Humicola lanuginosa, Mucor miehei, Myceliophthora thermophila, Neurospora crassa, Penicillium purpurogenum, Phanerochaete chrysosporium, Phlebia radiata, Pleurotus eryngii, Talaromyces emersonii, Thielavia terrestris, Trametes villosa, Trametes versicolor, Trichoderma harzianum, Trichoderma koningii, Trichoderma longibrachiatum, Trichoderma reesei , or Trichoderma viride cell.
Fungal cells may be transformed by a process involving protoplast formation, transformation of the protoplasts, and regeneration of the cell wall in a manner known per se. Suitable procedures for transformation of Aspergillus and Trichoderma host cells are described in EP 238023, Yelton et al., 1984 , Proc. Natl. Acad. Sci. USA 81: 1470-1474, and Christensen et al., 1988 , Bio/Technology 6: 1419-1422. Suitable methods for transforming Fusarium species are described by Malardier et al., 1989 , Gene 78: 147-156, and WO 96/00787. Yeast may be transformed using the procedures described by Becker and Guarente, In Abelson, J. N. and Simon, M. I., editors, Guide to Yeast Genetics and Molecular Biology, Methods in Enzymology , Volume 194, pp. 182-187, Academic Press, Inc., New York; Ito et al., 1983 , J. Bacteriol. 153: 163; and Hinnen et al., 1978 , Proc. Natl. Acad. Sci. USA 75: 1920.
Methods of Production
The present invention also relates to methods of producing a variant, comprising (a) cultivating a recombinant host cell of the present invention under conditions conducive for production of the variant; and optionally (b) recovering the variant.
The host cells are cultivated in a nutrient medium suitable for production of the variant using methods known in the art. For example, the cells may be cultivated by shake flask cultivation, or small-scale or large-scale fermentation (including continuous, batch, fed-batch, or solid state fermentations) in laboratory or industrial fermentors in a suitable medium and under conditions allowing the variant to be expressed and/or isolated. The cultivation takes place in a suitable nutrient medium comprising carbon and nitrogen sources and inorganic salts, using procedures known in the art. Suitable media are available from commercial suppliers or may be prepared according to published compositions (e.g., in catalogues of the American Type Culture Collection). If the variant is secreted into the nutrient medium, the variant can be recovered directly from the medium. If the variant is not secreted, it can be recovered from cell lysates.
The variants may be detected using methods known in the art that are specific for the variants. These detection methods include, but are not limited to, use of specific antibodies, formation of an enzyme product, or disappearance of an enzyme substrate. For example, an enzyme assay may be used to determine the activity of the variant.
The variant may be recovered using methods known in the art. For example, the variant may be recovered from the nutrient medium by conventional procedures including, but not limited to, collection, centrifugation, filtration, extraction, spray-drying, evaporation, or precipitation. In one aspect, a whole fermentation broth comprising a variant of the present invention is recovered.
The variant may be purified by a variety of procedures known in the art including, but not limited to, chromatography (e.g., ion exchange, affinity, hydrophobic, chromatofocusing, and size exclusion), electrophoretic procedures (e.g., preparative isoelectric focusing), differential solubility (e.g., ammonium sulfate precipitation), SDS-PAGE, or extraction (see, e.g., Protein Purification , Janson and Ryden, editors, VCH Publishers, New York, 1989) to obtain substantially pure variants.
Fermentation Broth Formulations or Cell Compositions
The present invention also relates to a fermentation broth formulation or a cell composition comprising a variant of the present invention. The fermentation broth product further comprises additional ingredients used in the fermentation process, such as, for example, cells (including, the host cells containing the gene encoding the variant of the present invention which are used to produce the variant), cell debris, biomass, fermentation media and/or fermentation products. In some embodiments, the composition is a cell-killed whole broth containing organic acid(s), killed cells and/or cell debris, and culture medium.
The term “fermentation broth” as used herein refers to a preparation produced by cellular fermentation that undergoes no or minimal recovery and/or purification. For example, fermentation broths are produced when microbial cultures are grown to saturation, incubated under carbon-limiting conditions to allow protein synthesis (e.g., expression of enzymes by host cells) and secretion into cell culture medium. The fermentation broth can contain unfractionated or fractionated contents of the fermentation materials derived at the end of the fermentation. Typically, the fermentation broth is unfractionated and comprises the spent culture medium and cell debris present after the microbial cells (e.g., filamentous fungal cells) are removed, e.g., by centrifugation. In some embodiments, the fermentation broth contains spent cell culture medium, extracellular enzymes, and viable and/or nonviable microbial cells.
In an embodiment, the fermentation broth formulation and cell compositions comprise a first organic acid component comprising at least one 1-5 carbon organic acid and/or a salt thereof and a second organic acid component comprising at least one 6 or more carbon organic acid and/or a salt thereof. In a specific embodiment, the first organic acid component is acetic acid, formic acid, propionic acid, a salt thereof, or a mixture of two or more of the foregoing and the second organic acid component is benzoic acid, cyclohexanecarboxylic acid, 4-methylvaleric acid, phenylacetic acid, a salt thereof, or a mixture of two or more of the foregoing.
In one aspect, the composition contains an organic acid(s), and optionally further contains killed cells and/or cell debris. In one embodiment, the killed cells and/or cell debris are removed from a cell-killed whole broth to provide a composition that is free of these components.
The fermentation broth formulations or cell compositions may further comprise a preservative and/or anti-microbial (e.g., bacteriostatic) agent, including, but not limited to, sorbitol, sodium chloride, potassium sorbate, and others known in the art.
The fermentation broth formulations or cell compositions may further comprise multiple enzymatic activities, such as one or more (e.g., several) enzymes selected from the group consisting of a cellulase, a hemicellulase, a catalase, an esterase, an expansin, a laccase, a ligninolytic enzyme, a pectinase, a peroxidase, a protease, and a swollenin. The fermentation broth formulations or cell compositions may also comprise one or more (e.g., several) enzymes selected from the group consisting of a hydrolase, an isomerase, a ligase, a lyase, an oxidoreductase, or a transferase, e.g., an alpha-galactosidase, alpha-glucosidase, aminopeptidase, amylase, beta-galactosidase, beta-glucosidase, beta-xylosidase, carbohydrase, carboxypeptidase, catalase, cellobiohydrolase, cellulase, chitinase, cutinase, cyclodextrin glycosyltransferase, deoxyribonuclease, endoglucanase, esterase, glucoamylase, invertase, laccase, lipase, mannosidase, mutanase, oxidase, pectinolytic enzyme, peroxidase, phytase, polyphenoloxidase, proteolytic enzyme, ribonuclease, transglutaminase, or xylanase.
The cell-killed whole broth or composition may contain the unfractionated contents of the fermentation materials derived at the end of the fermentation. Typically, the cell-killed whole broth or composition contains the spent culture medium and cell debris present after the microbial cells (e.g., filamentous fungal cells) are grown to saturation, incubated under carbon-limiting conditions to allow protein synthesis (e.g., expression of cellulase and/or glucosidase enzyme(s)). In some embodiments, the cell-killed whole broth or composition contains the spent cell culture medium, extracellular enzymes, and killed filamentous fungal cells. In some embodiments, the microbial cells present in the cell-killed whole broth or composition can be permeabilized and/or lysed using methods known in the art.
A whole broth or cell composition as described herein is typically a liquid, but may contain insoluble components, such as killed cells, cell debris, culture media components, and/or insoluble enzyme(s). In some embodiments, insoluble components may be removed to provide a clarified liquid composition.
The whole broth formulations and cell compositions of the present invention may be produced by a method described in WO 90/15861 or WO 2010/096673.
Examples are given below of preferred uses of the compositions of the present invention. The dosage of the composition and other conditions under which the composition is used may be determined on the basis of methods known in the art.
Enzyme Compositions
The present invention also relates to compositions comprising a variant of the present invention. Preferably, the compositions are enriched in such a variant. The term “enriched” indicates that the cellobiohydrolase activity of the composition has been increased, e.g., with an enrichment factor of at least 1.1.
The compositions may comprise a variant of the present invention as the major enzymatic component, e.g., a mono-component composition. Alternatively, the compositions may comprise multiple enzymatic activities, such as one or more (e.g., several) enzymes selected from the group consisting of a cellulase, a hemicellulase, a GH61 polypeptide having cellulolytic enhancing activity, a catalase, an esterase, an expansin, a laccase, a ligninolytic enzyme, a pectinase, a peroxidase, a protease, and a swollenin. The compositions may also comprise one or more (e.g., several) enzymes selected from the group consisting of a hydrolase, an isomerase, a ligase, a lyase, an oxidoreductase, or a transferase, e.g., an alpha-galactosidase, alpha-glucosidase, aminopeptidase, amylase, beta-galactosidase, beta-glucosidase, beta-xylosidase, carbohydrase, carboxypeptidase, catalase, cellobiohydrolase, cellulase, chitinase, cutinase, cyclodextrin glycosyltransferase, deoxyribonuclease, endoglucanase, esterase, glucoamylase, invertase, laccase, lipase, mannosidase, mutanase, oxidase, pectinolytic enzyme, peroxidase, phytase, polyphenoloxidase, proteolytic enzyme, ribonuclease, transglutaminase, or xylanase. The compositions may be prepared in accordance with methods known in the art and may be in the form of a liquid or a dry composition. The compositions may be stabilized in accordance with methods known in the art.
Examples are given below of preferred uses of the compositions of the present invention. The dosage of the composition and other conditions under which the composition is used may be determined on the basis of methods known in the art.
Uses
The present invention is also directed to the following processes for using the variants having cellobiohydrolase I activity of the present invention, or compositions thereof.
The present invention also relates to processes for degrading a cellulosic material, comprising: treating the cellulosic material with an enzyme composition in the presence of a cellobiohydrolase variant of the present invention. In one aspect, the processes further comprise recovering the degraded cellulosic material. Soluble products of degradation of the cellulosic material can be separated from insoluble cellulosic material using a method known in the art such as, for example, centrifugation, filtration, or gravity settling.
The present invention also relates to processes of producing a fermentation product, comprising: (a) saccharifying a cellulosic material with an enzyme composition in the presence of a cellobiohydrolase variant of the present invention; (b) fermenting the saccharified cellulosic material with one or more (e.g., several) fermenting microorganisms to produce the fermentation product; and (c) recovering the fermentation product from the fermentation.
The present invention also relates to processes of fermenting a cellulosic material, comprising: fermenting the cellulosic material with one or more (e.g., several) fermenting microorganisms, wherein the cellulosic material is saccharified with an enzyme composition in the presence of a cellobiohydrolase variant of the present invention. In one aspect, the fermenting of the cellulosic material produces a fermentation product. In another aspect, the processes further comprise recovering the fermentation product from the fermentation.
The processes of the present invention can be used to saccharify the cellulosic material to fermentable sugars and to convert the fermentable sugars to many useful fermentation products, e.g., fuel (ethanol, n-butanol, isobutanol, biodiesel, jet fuel) and/or platform chemicals (e.g., acids, alcohols, ketones, gases, oils, and the like). The production of a desired fermentation product from the cellulosic material typically involves pretreatment, enzymatic hydrolysis (saccharification), and fermentation.
The processing of the cellulosic material according to the present invention can be accomplished using methods conventional in the art. Moreover, the processes of the present invention can be implemented using any conventional biomass processing apparatus configured to operate in accordance with the invention.
Hydrolysis (saccharification) and fermentation, separate or simultaneous, include, but are not limited to, separate hydrolysis and fermentation (SHF); simultaneous saccharification and fermentation (SSF); simultaneous saccharification and co-fermentation (SSCF); hybrid hydrolysis and fermentation (HHF); separate hydrolysis and co-fermentation (SHCF); hybrid hydrolysis and co-fermentation (HHCF); and direct microbial conversion (DMC), also sometimes called consolidated bioprocessing (CBP). SHF uses separate process steps to first enzymatically hydrolyze the cellulosic material to fermentable sugars, e.g., glucose, cellobiose, and pentose monomers, and then ferment the fermentable sugars to ethanol. In SSF, the enzymatic hydrolysis of the cellulosic material and the fermentation of sugars to ethanol are combined in one step (Philippidis, G. P., 1996, Cellulose bioconversion technology, in Handbook on Bioethanol: Production and Utilization , Wyman, C. E., ed., Taylor & Francis, Washington, D.C., 179-212). SSCF involves the co-fermentation of multiple sugars (Sheehan and Himmel, 1999 , Biotechnol. Prog. 15: 817-827). HHF involves a separate hydrolysis step, and in addition a simultaneous saccharification and hydrolysis step, which can be carried out in the same reactor. The steps in an HHF process can be carried out at different temperatures, i.e., high temperature enzymatic saccharification followed by SSF at a lower temperature that the fermentation strain can tolerate. DMC combines all three processes (enzyme production, hydrolysis, and fermentation) in one or more (e.g., several) steps where the same organism is used to produce the enzymes for conversion of the cellulosic material to fermentable sugars and to convert the fermentable sugars into a final product (Lynd et al., 2002 , Microbiol. Mol. Biol. Reviews 66: 506-577). It is understood herein that any method known in the art comprising pretreatment, enzymatic hydrolysis (saccharification), fermentation, or a combination thereof, can be used in the practicing the processes of the present invention.
A conventional apparatus can include a fed-batch stirred reactor, a batch stirred reactor, a continuous flow stirred reactor with ultrafiltration, and/or a continuous plug-flow column reactor (de Castilhos Corazza et al., 2003 , Acta Scientiarum. Technology 25: 33-38; Gusakov and Sinitsyn, 1985 , Enz. Microb. Technol. 7: 346-352), an attrition reactor (Ryu and Lee, 1983 , Biotechnol. Bioeng. 25: 53-65). Additional reactor types include fluidized bed, upflow blanket, immobilized, and extruder type reactors for hydrolysis and/or fermentation.
Pretreatment.
In practicing the processes of the present invention, any pretreatment process known in the art can be used to disrupt plant cell wall components of the cellulosic material (Chandra et al., 2007 , Adv. Biochem. Engin./Biotechnol. 108: 67-93; Galbe and Zacchi, 2007 , Adv. Biochem. Engin./Biotechnol. 108: 41-65; Hendriks and Zeeman, 2009 , Bioresource Technol. 100: 10-18; Mosier et al., 2005 , Bioresource Technol. 96: 673-686; Taherzadeh and Karimi, 2008 , Int. J. Mol. Sci. 9: 1621-1651; Yang and Wyman, 2008 , Biofuels Bioproducts and Biorefining - Biofpr. 2: 26-40).
The cellulosic material can also be subjected to particle size reduction, sieving, pre-soaking, wetting, washing, and/or conditioning prior to pretreatment using methods known in the art.
Conventional pretreatments include, but are not limited to, steam pretreatment (with or without explosion), dilute acid pretreatment, hot water pretreatment, alkaline pretreatment, lime pretreatment, wet oxidation, wet explosion, ammonia fiber explosion, organosolv pretreatment, and biological pretreatment. Additional pretreatments include ammonia percolation, ultrasound, electroporation, microwave, supercritical CO 2 , supercritical H 2 O, ozone, ionic liquid, and gamma irradiation pretreatments.
The cellulosic material can be pretreated before hydrolysis and/or fermentation. Pretreatment is preferably performed prior to the hydrolysis. Alternatively, the pretreatment can be carried out simultaneously with enzyme hydrolysis to release fermentable sugars, such as glucose, xylose, and/or cellobiose. In most cases the pretreatment step itself results in some conversion of biomass to fermentable sugars (even in absence of enzymes).
Steam Pretreatment. In steam pretreatment, the cellulosic material is heated to disrupt the plant cell wall components, including lignin, hemicellulose, and cellulose to make the cellulose and other fractions, e.g., hemicellulose, accessible to enzymes. The cellulosic material is passed to or through a reaction vessel where steam is injected to increase the temperature to the required temperature and pressure and is retained therein for the desired reaction time. Steam pretreatment is preferably performed at 140-250° C., e.g., 160-200° C. or 170-190° C., where the optimal temperature range depends on optional addition of a chemical catalyst. Residence time for the steam pretreatment is preferably 1-60 minutes, e.g., 1-30 minutes, 1-20 minutes, 3-12 minutes, or 4-10 minutes, where the optimal residence time depends on the temperature and optional addition of a chemical catalyst. Steam pretreatment allows for relatively high solids loadings, so that the cellulosic material is generally only moist during the pretreatment. The steam pretreatment is often combined with an explosive discharge of the material after the pretreatment, which is known as steam explosion, that is, rapid flashing to atmospheric pressure and turbulent flow of the material to increase the accessible surface area by fragmentation (Duff and Murray, 1996 , Bioresource Technology 855: 1-33; Galbe and Zacchi, 2002 , Appl. Microbiol. Biotechnol. 59: 618-628; U.S. Patent Application No. 2002/0164730). During steam pretreatment, hemicellulose acetyl groups are cleaved and the resulting acid autocatalyzes partial hydrolysis of the hemicellulose to monosaccharides and oligosaccharides. Lignin is removed to only a limited extent.
Chemical Pretreatment: The term “chemical treatment” refers to any chemical pretreatment that promotes the separation and/or release of cellulose, hemicellulose, and/or lignin. Such a pretreatment can convert crystalline cellulose to amorphous cellulose. Examples of suitable chemical pretreatment processes include, for example, dilute acid pretreatment, lime pretreatment, wet oxidation, ammonia fiber/freeze expansion (AFEX), ammonia percolation (APR), ionic liquid, and organosolv pretreatments.
A chemical catalyst such as H 2 SO 4 or SO 2 (typically 0.3 to 5% w/w) is sometimes added prior to steam pretreatment, which decreases the time and temperature, increases the recovery, and improves enzymatic hydrolysis (Ballesteros et al., 2006 , Appl. Biochem. Biotechnol. 129-132: 496-508; Varga et al., 2004 , Appl. Biochem. Biotechnol. 113-116: 509-523; Sassner et al., 2006 , Enzyme Microb. Technol. 39: 756-762). In dilute acid pretreatment, the cellulosic material is mixed with dilute acid, typically H 2 SO 4 , and water to form a slurry, heated by steam to the desired temperature, and after a residence time flashed to atmospheric pressure. The dilute acid pretreatment can be performed with a number of reactor designs, e.g., plug-flow reactors, counter-current reactors, or continuous counter-current shrinking bed reactors (Duff and Murray, 1996, supra; Schell et al., 2004 , Bioresource Technology 91: 179-188; Lee et al., 1999 , Adv. Biochem. Eng. Biotechnol. 65: 93-115).
Several methods of pretreatment under alkaline conditions can also be used. These alkaline pretreatments include, but are not limited to, sodium hydroxide, lime, wet oxidation, ammonia percolation (APR), and ammonia fiber/freeze expansion (AFEX) pretreatment.
Lime pretreatment is performed with calcium oxide or calcium hydroxide at temperatures of 85-150° C. and residence times from 1 hour to several days (Wyman et al., 2005 , Bioresource Technol. 96: 1959-1966; Mosier et al., 2005 , Bioresource Technol. 96: 673-686). WO 2006/110891, WO 2006/110899, WO 2006/110900, and WO 2006/110901 disclose pretreatment methods using ammonia.
Wet oxidation is a thermal pretreatment performed typically at 180-200° C. for 5-15 minutes with addition of an oxidative agent such as hydrogen peroxide or over-pressure of oxygen (Schmidt and Thomsen, 1998 , Bioresource Technol. 64: 139-151; Palonen et al., 2004 , Appl. Biochem. Biotechnol. 117: 1-17; Varga et al., 2004 , Biotechnol. Bioeng. 88: 567-574; Martin et al., 2006 , J. Chem. Technol. Biotechnol. 81: 1669-1677). The pretreatment is performed preferably at 1-40% dry matter, e.g., 2-30% dry matter or 5-20% dry matter, and often the initial pH is increased by the addition of alkali such as sodium carbonate.
A modification of the wet oxidation pretreatment method, known as wet explosion (combination of wet oxidation and steam explosion) can handle dry matter up to 30%. In wet explosion, the oxidizing agent is introduced during pretreatment after a certain residence time. The pretreatment is then ended by flashing to atmospheric pressure (WO 2006/032282).
Ammonia fiber expansion (AFEX) involves treating the cellulosic material with liquid or gaseous ammonia at moderate temperatures such as 90-150° C. and high pressure such as 17-20 bar for 5-10 minutes, where the dry matter content can be as high as 60% (Gollapalli et al., 2002 , Appl. Biochem. Biotechnol. 98: 23-35; Chundawat et al., 2007 , Biotechnol. Bioeng. 96: 219-231; Alizadeh et al., 2005 , Appl. Biochem. Biotechnol. 121: 1133-1141; Teymouri et al., 2005 , Bioresource Technology 96: 2014-2018). During AFEX pretreatment cellulose and hemicelluloses remain relatively intact. Lignin-carbohydrate complexes are cleaved.
Organosolv pretreatment delignifies the cellulosic material by extraction using aqueous ethanol (40-60% ethanol) at 160-200° C. for 30-60 minutes (Pan et al., 2005 , Biotechnol. Bioeng. 90: 473-481; Pan et al., 2006 , Biotechnol. Bioeng. 94: 851-861; Kurabi et al., 2005 , Appl. Biochem. Biotechnol. 121: 219-230). Sulphuric acid is usually added as a catalyst. In organosolv pretreatment, the majority of hemicellulose and lignin is removed.
Other examples of suitable pretreatment methods are described by Schell et al., 2003 , Appl. Biochem. Biotechnol. 105-108: 69-85, and Mosier et al., 2005 , Bioresource Technology 96: 673-686, and U.S. Published Application 2002/0164730.
In one aspect, the chemical pretreatment is preferably carried out as a dilute acid treatment, and more preferably as a continuous dilute acid treatment. The acid is typically sulfuric acid, but other acids can also be used, such as acetic acid, citric acid, nitric acid, phosphoric acid, tartaric acid, succinic acid, hydrogen chloride, or mixtures thereof. Mild acid treatment is conducted in the pH range of preferably 1-5, e.g., 1-4 or 1-2.5. In one aspect, the acid concentration is in the range from preferably 0.01 to 10 wt. % acid, e.g., 0.05 to 5 wt. % acid or 0.1 to 2 wt. % acid. The acid is contacted with the cellulosic material and held at a temperature in the range of preferably 140-200° C., e.g., 165-190° C., for periods ranging from 1 to 60 minutes.
In another aspect, pretreatment takes place in an aqueous slurry. In preferred aspects, the cellulosic material is present during pretreatment in amounts preferably between 10-80 wt %, e.g., 20-70 wt % or 30-60 wt %, such as around 40 wt %. The pretreated cellulosic material can be unwashed or washed using any method known in the art, e.g., washed with water.
Mechanical Pretreatment or Physical Pretreatment: The term “mechanical pretreatment” or “physical pretreatment” refers to any pretreatment that promotes size reduction of particles. For example, such pretreatment can involve various types of grinding or milling (e.g., dry milling, wet milling, or vibratory ball milling).
The cellulosic material can be pretreated both physically (mechanically) and chemically. Mechanical or physical pretreatment can be coupled with steaming/steam explosion, hydrothermolysis, dilute or mild acid treatment, high temperature, high pressure treatment, irradiation (e.g., microwave irradiation), or combinations thereof. In one aspect, high pressure means pressure in the range of preferably about 100 to about 400 psi, e.g., about 150 to about 250 psi. In another aspect, high temperature means temperature in the range of about 100 to about 300° C., e.g., about 140 to about 200° C. In a preferred aspect, mechanical or physical pretreatment is performed in a batch-process using a steam gun hydrolyzer system that uses high pressure and high temperature as defined above, e.g., a Sunds Hydrolyzer available from Sunds Defibrator AB, Sweden. The physical and chemical pretreatments can be carried out sequentially or simultaneously, as desired.
Accordingly, in a preferred aspect, the cellulosic material is subjected to physical (mechanical) or chemical pretreatment, or any combination thereof, to promote the separation and/or release of cellulose, hemicellulose, and/or lignin.
Biological Pretreatment: The term “biological pretreatment” refers to any biological pretreatment that promotes the separation and/or release of cellulose, hemicellulose, and/or lignin from the cellulosic material. Biological pretreatment techniques can involve applying lignin-solubilizing microorganisms and/or enzymes (see, for example, Hsu, T.-A., 1996, Pretreatment of biomass, in Handbook on Bioethanol: Production and Utilization , Wyman, C. E., ed., Taylor & Francis, Washington, D.C., 179-212; Ghosh and Singh, 1993 , Adv. Appl. Microbiol. 39: 295-333; McMillan, J. D., 1994, Pretreating lignocellulosic biomass: a review, in Enzymatic Conversion of Biomass for Fuels Production , Himmel, M. E., Baker, J. O., and Overend, R. P., eds., ACS Symposium Series 566, American Chemical Society, Washington, D.C., chapter 15; Gong, C. S., Cao, N. J., Du, J., and Tsao, G. T., 1999, Ethanol production from renewable resources, in Advances in Biochemical Engineering/Biotechnology , Scheper, T., ed., Springer-Verlag Berlin Heidelberg, Germany, 65: 207-241; Olsson and Hahn-Hagerdal, 1996 , Enz. Microb. Tech. 18: 312-331; and Vallander and Eriksson, 1990 , Adv. Biochem. Eng./Biotechnol. 42: 63-95).
Saccharification.
In the hydrolysis step, also known as saccharification, the cellulosic material, e.g., pretreated, is hydrolyzed to break down cellulose and/or hemicellulose to fermentable sugars, such as glucose, cellobiose, xylose, xylulose, arabinose, mannose, galactose, and/or soluble oligosaccharides. The hydrolysis is performed enzymatically by an enzyme composition in the presence of a cellobiohydrolase variant of the present invention. The enzymes of the compositions can be added simultaneously or sequentially.
Enzymatic hydrolysis is preferably carried out in a suitable aqueous environment under conditions that can be readily determined by one skilled in the art. In one aspect, hydrolysis is performed under conditions suitable for the activity of the enzymes(s), i.e., optimal for the enzyme(s). The hydrolysis can be carried out as a fed batch or continuous process where the cellulosic material is fed gradually to, for example, an enzyme containing hydrolysis solution.
The saccharification is generally performed in stirred-tank reactors or fermentors under controlled pH, temperature, and mixing conditions. Suitable process time, temperature and pH conditions can readily be determined by one skilled in the art. For example, the saccharification can last up to 200 hours, but is typically performed for preferably about 12 to about 120 hours, e.g., about 16 to about 72 hours or about 24 to about 48 hours. The temperature is in the range of preferably about 25° C. to about 70° C., e.g., about 30° C. to about 65° C., about 40° C. to about 60° C., or about 50° C. to about 55° C. The pH is in the range of preferably about 3 to about 8, e.g., about 3.5 to about 7, about 4 to about 6, or about 4.5 to about 5.5. The dry solids content is in the range of preferably about 5 to about 50 wt %, e.g., about 10 to about 40 wt % or about 20 to about 30 wt %.
The enzyme compositions can comprise any protein useful in degrading the cellulosic material.
In one aspect, the enzyme composition comprises or further comprises one or more (e.g., several) proteins selected from the group consisting of a cellulase, a GH61 polypeptide having cellulolytic enhancing activity, a hemicellulase, an esterase, an expansin, a ligninolytic enzyme, an oxidoreductase, a pectinase, a protease, and a swollenin. In another aspect, the cellulase is preferably one or more (e.g., several) enzymes selected from the group consisting of an endoglucanase, a cellobiohydrolase, and a beta-glucosidase. In another aspect, the hemicellulase is preferably one or more (e.g., several) enzymes selected from the group consisting of an acetylmannan esterase, an acetylxylan esterase, an arabinanase, an arabinofuranosidase, a coumaric acid esterase, a feruloyl esterase, a galactosidase, a glucuronidase, a glucuronoyl esterase, a mannanase, a mannosidase, a xylanase, and a xylosidase. In another aspect, the oxidoreductase is preferably one or more (e.g., several) enzymes selected from the group consisting of a catalase, a laccase, and a peroxidase.
In another aspect, the enzyme composition comprises one or more (e.g., several) cellulolytic enzymes. In another aspect, the enzyme composition comprises or further comprises one or more (e.g., several) hemicellulolytic enzymes. In another aspect, the enzyme composition comprises one or more (e.g., several) cellulolytic enzymes and one or more (e.g., several) hemicellulolytic enzymes. In another aspect, the enzyme composition comprises one or more (e.g., several) enzymes selected from the group of cellulolytic enzymes and hemicellulolytic enzymes. In another aspect, the enzyme composition comprises an endoglucanase. In another aspect, the enzyme composition comprises a cellobiohydrolase. In another aspect, the enzyme composition comprises a beta-glucosidase. In another aspect, the enzyme composition comprises a GH61 polypeptide having cellulolytic enhancing activity. In another aspect, the enzyme composition comprises an endoglucanase and a GH61 polypeptide having cellulolytic enhancing activity. In another aspect, the enzyme composition comprises a cellobiohydrolase and a GH61 polypeptide having cellulolytic enhancing activity. In another aspect, the enzyme composition comprises a beta-glucosidase and a GH61 polypeptide having cellulolytic enhancing activity. In another aspect, the enzyme composition comprises an endoglucanase and a cellobiohydrolase. In another aspect, the enzyme composition comprises an endoglucanase and a cellobiohydrolase I, a cellobiohydrolase II, or a combination of a cellobiohydrolase I and a cellobiohydrolase II. In another aspect, the enzyme composition comprises an endoglucanase and a beta-glucosidase. In another aspect, the enzyme composition comprises a beta-glucosidase and a cellobiohydrolase. In another aspect, the enzyme composition comprises a beta-glucosidase and a cellobiohydrolase I, a cellobiohydrolase II, or a combination of a cellobiohydrolase I and a cellobiohydrolase II In another aspect, the enzyme composition comprises an endoglucanase, a GH61 polypeptide having cellulolytic enhancing activity, and a cellobiohydrolase. In another aspect, the enzyme composition comprises an endoglucanase, a GH61 polypeptide having cellulolytic enhancing activity, and a cellobiohydrolase I, a cellobiohydrolase II, or a combination of a cellobiohydrolase I and a cellobiohydrolase II. In another aspect, the enzyme composition comprises an endoglucanase, a beta-glucosidase, and a GH61 polypeptide having cellulolytic enhancing activity. In another aspect, the enzyme composition comprises a beta-glucosidase, a GH61 polypeptide having cellulolytic enhancing activity, and a cellobiohydrolase. In another aspect, the enzyme composition comprises a beta-glucosidase, a GH61 polypeptide having cellulolytic enhancing activity, and a cellobiohydrolase I, a cellobiohydrolase II, or a combination of a cellobiohydrolase I and a cellobiohydrolase II. In another aspect, the enzyme composition comprises an endoglucanase, a beta-glucosidase, and a cellobiohydrolase. In another aspect, the enzyme composition comprises an endoglucanase, a beta-glucosidase, and a cellobiohydrolase I, a cellobiohydrolase II, or a combination of a cellobiohydrolase I and a cellobiohydrolase II. In another aspect, the enzyme composition comprises an endoglucanase, a cellobiohydrolase, a beta-glucosidase, and a GH61 polypeptide having cellulolytic enhancing activity. In another aspect, the enzyme composition comprises an endoglucanase, a beta-glucosidase, a GH61 polypeptide having cellulolytic enhancing activity, and a cellobiohydrolase I, a cellobiohydrolase II, or a combination of a cellobiohydrolase I and a cellobiohydrolase II.
In another aspect, the enzyme composition comprises an acetylmannan esterase. In another aspect, the enzyme composition comprises an acetylxylan esterase. In another aspect, the enzyme composition comprises an arabinanase (e.g., alpha-L-arabinanase). In another aspect, the enzyme composition comprises an arabinofuranosidase (e.g., alpha-L-arabinofuranosidase). In another aspect, the enzyme composition comprises a coumaric acid esterase. In another aspect, the enzyme composition comprises a feruloyl esterase. In another aspect, the enzyme composition comprises a galactosidase (e.g., alpha-galactosidase and/or beta-galactosidase). In another aspect, the enzyme composition comprises a glucuronidase (e.g., alpha-D-glucuronidase). In another aspect, the enzyme composition comprises a glucuronoyl esterase. In another aspect, the enzyme composition comprises a mannanase. In another aspect, the enzyme composition comprises a mannosidase (e.g., beta-mannosidase). In another aspect, the enzyme composition comprises a xylanase. In a preferred aspect, the xylanase is a Family 10 xylanase. In another preferred aspect, the xylanase is a Family 11 xylanase. In another aspect, the enzyme composition comprises a xylosidase (e.g., beta-xylosidase).
In another aspect, the enzyme composition comprises an esterase. In another aspect, the enzyme composition comprises an expansin. In another aspect, the enzyme composition comprises a ligninolytic enzyme. In a preferred aspect, the ligninolytic enzyme is a manganese peroxidase. In another preferred aspect, the ligninolytic enzyme is a lignin peroxidase. In another preferred aspect, the ligninolytic enzyme is a H 2 O 2 -producing enzyme. In another aspect, the enzyme composition comprises a pectinase. In another aspect, the enzyme composition comprises an oxidoreductase. In another preferred aspect, the oxidoreductase is a catalase. In another preferred aspect, the oxidoreductase is a laccase. In another preferred aspect, the oxidoreductase is a peroxidase. In another aspect, the enzyme composition comprises a protease. In another aspect, the enzyme composition comprises a swollenin.
In the processes of the present invention, the enzyme(s) can be added prior to or during saccharification, saccharification and fermentation, or fermentation.
One or more (e.g., several) components of the enzyme composition may be native proteins, recombinant proteins, or a combination of native proteins and recombinant proteins. For example, one or more (e.g., several) components may be native proteins of a cell, which is used as a host cell to express recombinantly one or more (e.g., several) other components of the enzyme composition. It is understood herein that the recombinant proteins may be heterologous (e.g., foreign) and native to the host cell. One or more (e.g., several) components of the enzyme composition may be produced as monocomponents, which are then combined to form the enzyme composition. The enzyme composition may be a combination of multicomponent and monocomponent protein preparations.
The enzymes used in the processes of the present invention may be in any form suitable for use, such as, for example, a fermentation broth formulation or a cell composition, a cell lysate with or without cellular debris, a semi-purified or purified enzyme preparation, or a host cell as a source of the enzymes. The enzyme composition may be a dry powder or granulate, a non-dusting granulate, a liquid, a stabilized liquid, or a stabilized protected enzyme. Liquid enzyme preparations may, for instance, be stabilized by adding stabilizers such as a sugar, a sugar alcohol or another polyol, and/or lactic acid or another organic acid according to established processes.
The optimum amounts of the enzymes and the cellobiohydrolase variant depend on several factors including, but not limited to, the mixture of component cellulolytic enzymes and/or hemicellulolytic enzymes, the cellulosic material, the concentration of cellulosic material, the pretreatment(s) of the cellulosic material, temperature, time, pH, and inclusion of fermenting organism (e.g., for Simultaneous Saccharification and Fermentation).
In one aspect, an effective amount of cellulolytic or hemicellulolytic enzyme to the cellulosic material is about 0.5 to about 50 mg, e.g., about 0.5 to about 40 mg, about 0.5 to about 25 mg, about 0.75 to about 20 mg, about 0.75 to about 15 mg, about 0.5 to about 10 mg, or about 2.5 to about 10 mg per g of the cellulosic material.
In another aspect, an effective amount of a cellobiohydrolase variant to the cellulosic material is about 0.01 to about 50.0 mg, e.g., about 0.01 to about 40 mg, about 0.01 to about 30 mg, about 0.01 to about 20 mg, about 0.01 to about 10 mg, about 0.01 to about 5 mg, about 0.025 to about 1.5 mg, about 0.05 to about 1.25 mg, about 0.075 to about 1.25 mg, about 0.1 to about 1.25 mg, about 0.15 to about 1.25 mg, or about 0.25 to about 1.0 mg per g of the cellulosic material.
In another aspect, an effective amount of a cellobiohydrolase variant to cellulolytic or hemicellulolytic enzyme is about 0.005 to about 1.0 g, e.g., about 0.01 to about 1.0 g, about 0.15 to about 0.75 g, about 0.15 to about 0.5 g, about 0.1 to about 0.5 g, about 0.1 to about 0.25 g, or about 0.05 to about 0.2 g per g of cellulolytic or hemicellulolytic enzyme.
The polypeptides having cellulolytic enzyme activity or hemicellulolytic enzyme activity as well as other proteins/polypeptides useful in the degradation of the cellulosic material, e.g., GH61 polypeptides having cellulolytic enhancing activity, (collectively hereinafter “polypeptides having enzyme activity”) can be derived or obtained from any suitable origin, including, archaeal, bacterial, fungal, yeast, plant, or animal origin. The term “obtained” also means herein that the enzyme may have been produced recombinantly in a host organism employing methods described herein, wherein the recombinantly produced enzyme is either native or foreign to the host organism or has a modified amino acid sequence, e.g., having one or more (e.g., several) amino acids that are deleted, inserted and/or substituted, i.e., a recombinantly produced enzyme that is a mutant and/or a fragment of a native amino acid sequence or an enzyme produced by nucleic acid shuffling processes known in the art. Encompassed within the meaning of a native enzyme are natural variants and within the meaning of a foreign enzyme are variants obtained by, for example, site-directed mutagenesis or shuffling.
A polypeptide having enzyme activity may be a bacterial polypeptide. For example, the polypeptide may be a Gram positive bacterial polypeptide such as a Bacillus, Streptococcus, Streptomyces, Staphylococcus, Enterococcus, Lactobacillus, Lactococcus, Clostridium, Geobacillus, Caldicellulosiruptor, Acidothermus, Thermobifidia , or Oceanobacillus polypeptide having enzyme activity, or a Gram negative bacterial polypeptide such as an E. coli, Pseudomonas, Salmonella, Campylobacter, Helicobacter, Flavobacterium, Fusobacterium, Ilyobacter, Neisseria , or Ureaplasma polypeptide having enzyme activity.
In one aspect, the polypeptide is a Bacillus alkalophilus, Bacillus amyloliquefaciens, Bacillus brevis, Bacillus circulans, Bacillus clausii, Bacillus coagulans, Bacillus firmus, Bacillus lautus, Bacillus lentus, Bacillus licheniformis, Bacillus megaterium, Bacillus pumilus, Bacillus stearothermophilus, Bacillus subtilis , or Bacillus thuringiensis polypeptide having enzyme activity.
In another aspect, the polypeptide is a Streptococcus equisimilis, Streptococcus pyogenes, Streptococcus uberis , or Streptococcus equi subsp. Zooepidemicus polypeptide having enzyme activity.
In another aspect, the polypeptide is a Streptomyces achromogenes, Streptomyces avermitilis, Streptomyces coelicolor, Streptomyces griseus , or Streptomyces lividans polypeptide having enzyme activity.
The polypeptide having enzyme activity may also be a fungal polypeptide, and more preferably a yeast polypeptide such as a Candida, Kluyveromyces, Pichia, Saccharomyces, Schizosaccharomyces , or Yarrowia polypeptide having enzyme activity; or more preferably a filamentous fungal polypeptide such as an Acremonium, Agaricus, Alternaria, Aspergillus, Aureobasidium, Botryosphaeria, Ceriporiopsis, Chaetomidium, Chrysosporium, Claviceps, Cochliobolus, Coprinopsis, Coptotermes, Corynascus, Cryphonectria, Cryptococcus, Diplodia, Exidia, Filibasidium, Fusarium, Gibberella, Holomastigotoides, Humicola, Irpex, Lentinula, Leptospaeria, Magnaporthe, Melanocarpus, Meripilus, Mucor, Myceliophthora, Neocallimastix, Neurospora, Paecilomyces, Penicillium, Phanerochaete, Piromyces, Poitrasia, Pseudoplectania, Pseudotrichonympha, Rhizomucor, Schizophyllum, Scytalidium, Talaromyces, Thermoascus, Thielavia, Tolypocladium, Trichoderma, Trichophaea, Verticillium, Volvariella , or Xylaria polypeptide having enzyme activity.
In one aspect, the polypeptide is a Saccharomyces carlsbergensis, Saccharomyces cerevisiae, Saccharomyces diastaticus, Saccharomyces douglasii, Saccharomyces kluyveri, Saccharomyces norbensis , or Saccharomyces oviformis polypeptide having enzyme activity.
In another aspect, the polypeptide is an Acremonium cellulolyticus, Aspergillus aculeatus, Aspergillus awamori, Aspergillus fumigatus, Aspergillus foetidus, Aspergillus japonicus, Aspergillus nidulans, Aspergillus niger, Aspergillus oryzae, Chrysosporium keratinophilum, Chrysosporium lucknowense, Chrysosporium tropicum, Chrysosporium merdarium, Chrysosporium inops, Chrysosporium pannicola, Chrysosporium queenslandicum, Chrysosporium zonatum, Fusarium bactridioides, Fusarium cerealis, Fusarium crookwellense, Fusarium culmorum, Fusarium graminearum, Fusarium graminurn, Fusarium heterosporum, Fusarium negundi, Fusarium oxysporum, Fusarium reticulaturn, Fusarium roseum, Fusarium sambucinum, Fusarium sarcochroum, Fusarium sporotrichioides, Fusarium sulphureum, Fusarium torulosum, Fusarium trichothecioides, Fusarium venenatum, Humicola grisea, Humicola insolens, Humicola lanuginosa, Irpex lacteus, Mucor miehei, Myceliophthora thermophila, Neurospora crassa, Penicillium funiculosum, Penicillium purpurogenum, Phanerochaete chrysosporium, Thielavia achromatica, Thielavia albomyces, Thielavia albopilosa, Thielavia australeinsis, Thielavia fimeti, Thielavia microspora, Thielavia ovispora, Thielavia peruviana, Thielavia spededonium, Thielavia setosa, Thielavia subthermophila, Thielavia terrestris, Trichoderma harzianurn, Trichoderma koningii, Trichoderma longibrachiatum, Trichoderma reesei, Trichoderma viride , or Trichophaea saccata polypeptide having enzyme activity.
Chemically modified or protein engineered mutants of polypeptides having enzyme activity may also be used.
One or more (e.g., several) components of the enzyme composition may be a recombinant component, i.e., produced by cloning of a DNA sequence encoding the single component and subsequent cell transformed with the DNA sequence and expressed in a host (see, for example, WO 91/17243 and WO 91/17244). The host can be a heterologous host (enzyme is foreign to host), but the host may under certain conditions also be a homologous host (enzyme is native to host). Monocomponent cellulolytic proteins may also be prepared by purifying such a protein from a fermentation broth.
In one aspect, the one or more (e.g., several) cellulolytic enzymes comprise a commercial cellulolytic enzyme preparation. Examples of commercial cellulolytic enzyme preparations suitable for use in the present invention include, for example, CELLIC® CTec (Novozymes NS), CELLIC® CTec2 (Novozymes NS), CELLIC® CTec3 (Novozymes NS), CELLUCLAST™ (Novozymes NS), NOVOZYM™ 188 (Novozymes NS), SPEZYME™ CP (Genencor Int.), ACCELLERASE™ TRIO (DuPont), FILTRASE® NL (DSM); METHAPLUS® S/L 100 (DSM), ROHAMENT™ 7069 W (Röhm GmbH), or ALTERNAFUEL® CMAX3™ (Dyadic International, Inc.). The cellulolytic enzyme preparation is added in an amount effective from about 0.001 to about 5.0 wt. % of solids, e.g., about 0.025 to about 4.0 wt. % of solids or about 0.005 to about 2.0 wt. % of solids.
Examples of bacterial endoglucanases that can be used in the processes of the present invention, include, but are not limited to, Acidothermus cellulolyticus endoglucanase (WO 91/05039; WO 93/15186; U.S. Pat. No. 5,275,944; WO 96/02551; U.S. Pat. No. 5,536,655; WO 00/70031; WO 05/093050), Erwinia carotovara endoglucanase (Saarilahti et al., 1990 , Gene 90: 9-14), Thermobifida fusca endoglucanase III (WO 05/093050), and Thermobifida fusca endoglucanase V (WO 05/093050).
Examples of fungal endoglucanases that can be used in the present invention, include, but are not limited to, Trichoderma reesei endoglucanase I (Penttila et al., 1986 , Gene 45: 253-263, Trichoderma reesei Cel7B endoglucanase I (GenBank:M15665), Trichoderma reesei endoglucanase II (Saloheimo et al., 1988, Gene 63:11-22), Trichoderma reesei Cel5A endoglucanase II (GenBank:M19373), Trichoderma reesei endoglucanase III (Okada et al., 1988 , Appl. Environ. Microbiol. 64: 555-563, GenBank:AB003694), Trichoderma reesei endoglucanase V (Saloheimo et al., 1994 , Molecular Microbiology 13: 219-228, GenBank:Z33381), Aspergillus aculeatus endoglucanase (Ooi et al., 1990 , Nucleic Acids Research 18: 5884), Aspergillus kawachii endoglucanase (Sakamoto et al., 1995 , Current Genetics 27: 435-439), Fusarium oxysporum endoglucanase (GenBank:L29381), Humicola grisea var. thermoidea endoglucanase (GenBank:AB003107), Melanocarpus albomyces endoglucanase (GenBank:MAL515703), Neurospora crassa endoglucanase (Gen Bank:XM_324477), Humicola insolens endoglucanase V, Myceliophthora thermophila CBS 117.65 endoglucanase, Thermoascus aurantiacus endoglucanase I (GenBank:AF487830), Trichoderma reesei strain No. VTT-D-80133 endoglucanase (GenBank:M15665), and Penicillium pinophilum endoglucanase (WO 2012/062220).
Examples of cellobiohydrolases useful in the present invention include, but are not limited to, Aspergillus aculeatus cellobiohydrolase II (WO 2011/059740), Aspergillus fumigatus cellobiohydrolase I (WO 2013/028928), Aspergillus fumigatus cellobiohydrolase II (WO 2013/028928), Chaetomium thermophilum cellobiohydrolase I, Chaetomium thermophilum cellobiohydrolase II, Humicola insolens cellobiohydrolase I, Myceliophthora thermophila cellobiohydrolase II (WO 2009/042871), Penicillium occitanis cellobiohydrolase I (GenBank:AY690482), Talaromyces emersonii cellobiohydrolase I (GenBank:AF439936), Thielavia hyrcanie cellobiohydrolase II (WO 2010/141325), Thielavia terrestris cellobiohydrolase II (CEL6A, WO 2006/074435), Trichoderma reesei cellobiohydrolase I, Trichoderma reesei cellobiohydrolase II, and Trichophaea saccata cellobiohydrolase II (WO 2010/057086).
Examples of beta-glucosidases useful in the present invention include, but are not limited to, beta-glucosidases from Aspergillus aculeatus (Kawaguchi et al., 1996 , Gene 173: 287-288), Aspergillus fumigatus (WO 2005/047499), Aspergillus niger (Dan et al., 2000 , J. Biol. Chem. 275: 4973-4980), Aspergillus oryzae (WO 02/095014), Penicillium brasilianum IBT 20888 (WO 2007/019442 and WO 2010/088387), Thielavia terrestris (WO 2011/035029), and Trichophaea saccata (WO 2007/019442).
The beta-glucosidase may be a fusion protein. In one aspect, the beta-glucosidase is an Aspergillus oryzae beta-glucosidase variant BG fusion protein (WO 2008/057637) or an Aspergillus oryzae beta-glucosidase fusion protein (WO 2008/057637).
Other useful endoglucanases, cellobiohydrolases, and beta-glucosidases are disclosed in numerous Glycosyl Hydrolase families using the classification according to Henrissat, 1991 , Biochem. J. 280: 309-316, and Henrissat and Bairoch, 1996 , Biochem. J. 316: 695-696.
Other cellulolytic enzymes that may be used in the present invention are described in WO 98/13465, WO 98/015619, WO 98/015633, WO 99/06574, WO 99/10481, WO 99/025847, WO 99/031255, WO 2002/101078, WO 2003/027306, WO 2003/052054, WO 2003/052055, WO 2003/052056, WO 2003/052057, WO 2003/052118, WO 2004/016760, WO 2004/043980, WO 2004/048592, WO 2005/001065, WO 2005/028636, WO 2005/093050, WO 2005/093073, WO 2006/074005, WO 2006/117432, WO 2007/071818, WO 2007/071820, WO 2008/008070, WO 2008/008793, U.S. Pat. No. 5,457,046, U.S. Pat. No. 5,648,263, and U.S. Pat. No. 5,686,593.
In the processes of the present invention, any GH61 polypeptide having cellulolytic enhancing activity can be used as a component of the enzyme composition.
Examples of GH61 polypeptides useful in the processes of the present invention include, but are not limited to, GH61 polypeptides from Thielavia terrestris (WO 2005/074647, WO 2008/148131, and WO 2011/035027), Thermoascus aurantiacus (WO 2005/074656 and WO 2010/065830), Trichoderma reesei (WO 2007/089290 and WO 2012/149344), Myceliophthora thermophila (WO 2009/085935, WO 2009/085859, WO 2009/085864, WO 2009/085868, and WO 2009/033071), Aspergillus fumigatus (WO 2010/138754), Penicillium pinophilum (WO 2011/005867), Thermoascus sp. (WO 2011/039319), Penicillium sp. ( emersonii ) (WO 2011/041397 and WO 2012/000892), Thermoascus crustaceous (WO 2011/041504), Aspergillus aculeatus (WO 2012/125925), Thermomyces lanuginosus (WO 2012/113340, WO 2012/129699, WO 2012/130964, and WO 2012/129699), Aurantiporus alborubescens (WO 2012/122477), Trichophaea saccata (WO 2012/122477), Penicillium thomii (WO 2012/122477), Talaromyces stipitatus (WO 2012/135659), Humicola insolens (WO 2012/146171), Malbranchea cinnamomea (WO 2012/101206), Talaromyces leycettanus (WO 2012/101206), and Chaetomium thermophilum (WO 2012/101206), and Talaromyces thermophilus (WO 2012/129697 and WO 2012/130950).
In one aspect, the GH61 polypeptide having cellulolytic enhancing activity is used in the presence of a soluble activating divalent metal cation according to WO 2008/151043, e.g., manganese or copper.
In another aspect, the GH61 polypeptide having cellulolytic enhancing activity is used in the presence of a dioxy compound, a bicylic compound, a heterocyclic compound, a nitrogen-containing compound, a quinone compound, a sulfur-containing compound, or a liquor obtained from a pretreated cellulosic material such as pretreated corn stover (WO 2012/021394, WO 2012/021395, WO 2012/021396, WO 2012/021399, WO 2012/021400, WO 2012/021401, WO 2012/021408, and WO 2012/021410).
The dioxy compound may include any suitable compound containing two or more oxygen atoms. In some aspects, the dioxy compounds contain a substituted aryl moiety as described herein. The dioxy compounds may comprise one or more (e.g., several) hydroxyl and/or hydroxyl derivatives, but also include substituted aryl moieties lacking hydroxyl and hydroxyl derivatives. Non-limiting examples of the dioxy compounds include pyrocatechol or catechol; caffeic acid; 3,4-dihydroxybenzoic acid; 4-tert-butyl-5-methoxy-1,2-benzenediol; pyrogallol; gallic acid; methyl-3,4,5-trihydroxybenzoate; 2,3,4-trihydroxybenzophenone; 2,6-dimethoxyphenol; sinapinic acid; 3,5-dihydroxybenzoic acid; 4-chloro-1,2-benzenediol; 4-nitro-1,2-benzenediol; tannic acid; ethyl gallate; methyl glycolate; dihydroxyfumaric acid; 2-butyne-1,4-diol; (croconic acid; 1,3-propanediol; tartaric acid; 2,4-pentanediol; 3-ethyoxy-1,2-propanediol; 2,4,4′-trihydroxybenzophenone; cis-2-butene-1,4-diol; 3,4-dihydroxy-3-cyclobutene-1,2-dione; dihydroxyacetone; acrolein acetal; methyl-4-hydroxybenzoate; 4-hydroxybenzoic acid; and methyl-3,5-dimethoxy-4-hydroxybenzoate; or a salt or solvate thereof.
The bicyclic compound may include any suitable substituted fused ring system as described herein. The compounds may comprise one or more (e.g., several) additional rings, and are not limited to a specific number of rings unless otherwise stated. In one aspect, the bicyclic compound is a flavonoid. In another aspect, the bicyclic compound is an optionally substituted isoflavonoid. In another aspect, the bicyclic compound is an optionally substituted flavylium ion, such as an optionally substituted anthocyanidin or optionally substituted anthocyanin, or derivative thereof. Non-limiting examples of the bicyclic compounds include epicatechin; quercetin; myricetin; taxifolin; kaempferol; morin; acacetin; naringenin; isorhamnetin; apigenin; cyanidin; cyanin; kuromanin; keracyanin; or a salt or solvate thereof.
The heterocyclic compound may be any suitable compound, such as an optionally substituted aromatic or non-aromatic ring comprising a heteroatom, as described herein. In one aspect, the heterocyclic is a compound comprising an optionally substituted heterocycloalkyl moiety or an optionally substituted heteroaryl moiety. In another aspect, the optionally substituted heterocycloalkyl moiety or optionally substituted heteroaryl moiety is an optionally substituted 5-membered heterocycloalkyl or an optionally substituted 5-membered heteroaryl moiety. In another aspect, the optionally substituted heterocycloalkyl or optionally substituted heteroaryl moiety is an optionally substituted moiety selected from pyrazolyl, furanyl, imidazolyl, isoxazolyl, oxadiazolyl, oxazolyl, pyrrolyl, pyridyl, pyrimidyl, pyridazinyl, thiazolyl, triazolyl, thienyl, dihydrothieno-pyrazolyl, thianaphthenyl, carbazolyl, benzimidazolyl, benzothienyl, benzofuranyl, indolyl, quinolinyl, benzotriazolyl, benzothiazolyl, benzooxazolyl, benzimidazolyl, isoquinolinyl, isoindolyl, acridinyl, benzoisazolyl, dimethylhydantoin, pyrazinyl, tetrahydrofuranyl, pyrrolinyl, pyrrolidinyl, morpholinyl, indolyl, diazepinyl, azepinyl, thiepinyl, piperidinyl, and oxepinyl. In another aspect, the optionally substituted heterocycloalkyl moiety or optionally substituted heteroaryl moiety is an optionally substituted furanyl. Non-limiting examples of the heterocyclic compounds include (1,2-dihydroxyethyl)-3,4-dihydroxyfuran-2(5H)-one; 4-hydroxy-5-methyl-3-furanone; 5-hydroxy-2(5H)-furanone; [1,2-dihydroxyethyl]furan-2,3,4(5H)-trione; α-hydroxy-γ-butyrolactone; ribonic γ-lactone; aldohexuronicaldohexuronic acid γ-lactone; gluconic acid δ-lactone; 4-hydroxycoumarin; dihydrobenzofuran; 5-(hydroxymethyl)furfural; furoin; 2(5H)-furanone; 5,6-dihydro-2H-pyran-2-one; and 5,6-dihydro-4-hydroxy-6-methyl-2H-pyran-2-one; or a salt or solvate thereof.
The nitrogen-containing compound may be any suitable compound with one or more nitrogen atoms. In one aspect, the nitrogen-containing compound comprises an amine, imine, hydroxylamine, or nitroxide moiety. Non-limiting examples of the nitrogen-containing compounds include acetone oxime; violuric acid; pyridine-2-aldoxime; 2-aminophenol; 1,2-benzenediamine; 2,2,6,6-tetramethyl-1-piperidinyloxy; 5,6,7,8-tetrahydrobiopterin; 6,7-dimethyl-5,6,7,8-tetrahydropterine; and maleamic acid; or a salt or solvate thereof.
The quinone compound may be any suitable compound comprising a quinone moiety as described herein. Non-limiting examples of the quinone compounds include 1,4-benzoquinone; 1,4-naphthoquinone; 2-hydroxy-1,4-naphthoquinone; 2,3-dimethoxy-5-methyl-1,4-benzoquinone or coenzyme Q 0 ; 2,3,5,6-tetramethyl-1,4-benzoquinone or duroquinone; 1,4-dihydroxyanthraquinone; 3-hydroxy-1-methyl-5,6-indolinedione or adrenochrome; 4-tert-butyl-5-methoxy-1,2-benzoquinone; pyrroloquinoline quinone; or a salt or solvate thereof.
The sulfur-containing compound may be any suitable compound comprising one or more sulfur atoms. In one aspect, the sulfur-containing comprises a moiety selected from thionyl, thioether, sulfinyl, sulfonyl, sulfamide, sulfonamide, sulfonic acid, and sulfonic ester. Non-limiting examples of the sulfur-containing compounds include ethanethiol; 2-propanethiol; 2-propene-1-thiol; 2-mercaptoethanesulfonic acid; benzenethiol; benzene-1,2-dithiol; cysteine; methionine; glutathione; cystine; or a salt or solvate thereof.
In one aspect, an effective amount of such a compound described above is added to cellulosic material at a molar ratio of the compound to glucosyl units of cellulose of about 10 −6 to about 10, e.g., about 10 −6 to about 7.5, about 10 −6 to about 5, about 10 −6 to about 2.5, about 10 −6 to about 1, about 10 −5 to about 1, about 10 −5 to about 10 −1 , about 10 −4 to about 10 −1 , about 10 −3 to about 10 −1 , or about 10 −3 to about 10 −2 . In another aspect, an effective amount of such a compound is about 0.1 μM to about 1 M, e.g., about 0.5 μM to about 0.75 M, about 0.75 μM to about 0.5 M, about 1 μM to about 0.25 M, about 1 μM to about 0.1 M, about 5 μM to about 50 mM, about 10 μM to about 25 mM, about 50 μM to about 25 mM, about 10 μM to about 10 mM, about 5 μM to about 5 mM, or about 0.1 mM to about 1 mM.
The term “liquor” means the solution phase, either aqueous, organic, or a combination thereof, arising from treatment of a lignocellulose and/or hemicellulose material in a slurry, or monosaccharides thereof, e.g., xylose, arabinose, mannose, etc., under conditions as described in WO 2012/021401, and the soluble contents thereof. A liquor for cellulolytic enhancement of a GH61 polypeptide can be produced by treating a lignocellulose or hemicellulose material (or feedstock) by applying heat and/or pressure, optionally in the presence of a catalyst, e.g., acid, optionally in the presence of an organic solvent, and optionally in combination with physical disruption of the material, and then separating the solution from the residual solids. Such conditions determine the degree of cellulolytic enhancement obtainable through the combination of liquor and a GH61 polypeptide during hydrolysis of a cellulosic substrate by a cellulolytic enzyme preparation. The liquor can be separated from the treated material using a method standard in the art, such as filtration, sedimentation, or centrifugation.
In one aspect, an effective amount of the liquor to cellulose is about 10 −6 to about 10 g per g of cellulose, e.g., about 10 −6 to about 7.5 g, about 10 −6 to about 5 g, about 10 −6 to about 2.5 g, about 10 −6 to about 1 g, about 10 −5 to about 1 g, about 10 −5 to about 10 −1 g, about 10 −4 to about 10 −1 g, about 10 −3 to about 10 −1 g, or about 10 −3 to about 10 −2 g per g of cellulose.
In one aspect, the one or more (e.g., several) hemicellulolytic enzymes comprise a commercial hemicellulolytic enzyme preparation. Examples of commercial hemicellulolytic enzyme preparations suitable for use in the present invention include, for example, SHEARZYME™ (Novozymes NS), CELLIC® HTec (Novozymes NS), CELLIC® HTec2 (Novozymes NS), CELLIC® HTec3 (Novozymes NS), VISCOZYME® (Novozymes NS), ULTRAFLO® (Novozymes NS), PULPZYME® HC (Novozymes NS), MULTIFECT® Xylanase (Genencor), ACCELLERASE® XY (Genencor), ACCELLERASE® XC (Genencor), ECOPULP® TX-200A (AB Enzymes), HSP 6000 Xylanase (DSM), DEPOL™ 333P (Biocatalysts Limit, Wales, UK), DEPOL™ 740L. (Biocatalysts Limit, Wales, UK), and DEPOL™ 762P (Biocatalysts Limit, Wales, UK), ALTERNA FUEL 100P (Dyadic), and ALTERNA FUEL 200P (Dyadic).
Examples of xylanases useful in the processes of the present invention include, but are not limited to, xylanases from Aspergillus aculeatus (GeneSeqP:AAR63790; WO 94/21785), Aspergillus fumigatus (WO 2006/078256), Penicillium pinophilum (WO 2011/041405), Penicillium sp. (WO 2010/126772), Thermomyces lanuginosus (GeneSeqP:BAA22485), Talaromyces thermophilus (GeneSeqP:BAA22834), Thielavia terrestris NRRL 8126 (WO 2009/079210), and Trichophaea saccata (WO 2011/057083).
Examples of beta-xylosidases useful in the processes of the present invention include, but are not limited to, beta-xylosidases from Neurospora crassa (SwissProt:Q7SOW4), Trichoderma reesei (UniProtKB/TrEMBL:Q92458), Talaromyces emersonii (SwissProt:Q8X212), and Talaromyces thermophilus (GeneSeqP:BAA22816).
Examples of acetylxylan esterases useful in the processes of the present invention include, but are not limited to, acetylxylan esterases from Aspergillus aculeatus (WO 2010/108918), Chaetomium globosum (UniProt:Q2GWX4), Chaetomium gracile (GeneSeqP:AAB82124), Humicola insolens DSM 1800 (WO 2009/073709), Hypocrea jecorina (WO 2005/001036), Myceliophtera thermophila (WO 2010/014880), Neurospora crassa (UniProt:q7s259), Phaeosphaeria nodorum (UniProt:Q0UHJ1), and Thielavia terrestris NRRL 8126 (WO 2009/042846).
Examples of feruloyl esterases (ferulic acid esterases) useful in the processes of the present invention include, but are not limited to, feruloyl esterases form Humicola insolens DSM 1800 (WO 2009/076122), Neosartorya fischeri (UniProt:A1 D9T4), Neurospora crassa (UniProt:Q9HGR3), Penicillium aurantiogriseum (WO 2009/127729), and Thielavia terrestris (WO 2010/053838 and WO 2010/065448).
Examples of arabinofuranosidases useful in the processes of the present invention include, but are not limited to, arabinofuranosidases from Aspergillus niger (GeneSeqP:AAR94170), Humicola insolens DSM 1800 (WO 2006/114094 and WO 2009/073383), and M. giganteus (WO 2006/114094).
Examples of alpha-glucuronidases useful in the processes of the present invention include, but are not limited to, alpha-glucuronidases from Aspergillus clavatus (UniProt:alcc12), Aspergillus fumigatus (SwissProt:Q4WW45), Aspergillus niger (UniProt:Q96WX9), Aspergillus terreus (SwissProt:Q0CJ P9), Humicola insolens (WO 2010/014706), Penicillium aurantiogriseum (WO 2009/068565), Talaromyces emersonii (UniProt:Q8X211), and Trichoderma reesei (UniProt:Q99024).
Examples of oxidoreductases useful in the processes of the present invention include, but are not limited to, Aspergillus fumigatus catalase, Aspergillus lentilus catalase, Aspergillus niger catalase, Aspergillus oryzae catalase, Humicola insolens catalase, Neurospora crassa catalase, Penicillium emersonii catalase, Scytalidium thermophilum catalase, Talaromyces stipitatus catalase, Thermoascus aurantiacus catalase, Coprinus cinereus laccase, Myceliophthora thermophila laccase, Polyporus pinsitus laccase, Pycnoporus cinnabarinus laccase, Rhizoctonia solani laccase, Streptomyces coelicolor laccase, Coprinus cinereus peroxidase, Soy peroxidase, and Royal palm peroxidase.
The polypeptides having enzyme activity used in the processes of the present invention may be produced by fermentation of the above-noted microbial strains on a nutrient medium containing suitable carbon and nitrogen sources and inorganic salts, using procedures known in the art (see, e.g., Bennett, J. W. and LaSure, L. (eds.), More Gene Manipulations in Fungi , Academic Press, CA, 1991). Suitable media are available from commercial suppliers or may be prepared according to published compositions (e.g., in catalogues of the American Type Culture Collection). Temperature ranges and other conditions suitable for growth and enzyme production are known in the art (see, e.g., Bailey, J. E., and Ollis, D. F., Biochemical Engineering Fundamentals , McGraw-Hill Book Company, NY, 1986).
The fermentation can be any method of cultivation of a cell resulting in the expression or isolation of an enzyme or protein. Fermentation may, therefore, be understood as comprising shake flask cultivation, or small- or large-scale fermentation (including continuous, batch, fed-batch, or solid state fermentations) in laboratory or industrial fermentors performed in a suitable medium and under conditions allowing the enzyme to be expressed or isolated. The resulting enzymes produced by the methods described above may be recovered from the fermentation medium and purified by conventional procedures.
Fermentation.
The fermentable sugars obtained from the hydrolyzed cellulosic material can be fermented by one or more (e.g., several) fermenting microorganisms capable of fermenting the sugars directly or indirectly into a desired fermentation product. “Fermentation” or “fermentation process” refers to any fermentation process or any process comprising a fermentation step. Fermentation processes also include fermentation processes used in the consumable alcohol industry (e.g., beer and wine), dairy industry (e.g., fermented dairy products), leather industry, and tobacco industry. The fermentation conditions depend on the desired fermentation product and fermenting organism and can easily be determined by one skilled in the art.
In the fermentation step, sugars, released from the cellulosic material as a result of the pretreatment and enzymatic hydrolysis steps, are fermented to a product, e.g., ethanol, by a fermenting organism, such as yeast. Hydrolysis (saccharification) and fermentation can be separate or simultaneous.
Any suitable hydrolyzed cellulosic material can be used in the fermentation step in practicing the present invention. The material is generally selected based on economics, i.e., costs per equivalent sugar potential, and recalcitrance to enzymatic conversion.
The term “fermentation medium” is understood herein to refer to a medium before the fermenting microorganism(s) is(are) added, such as, a medium resulting from a saccharification process, as well as a medium used in a simultaneous saccharification and fermentation process (SSF).
“Fermenting microorganism” refers to any microorganism, including bacterial and fungal organisms, suitable for use in a desired fermentation process to produce a fermentation product. The fermenting organism can be hexose and/or pentose fermenting organisms, or a combination thereof. Both hexose and pentose fermenting organisms are well known in the art. Suitable fermenting microorganisms are able to ferment, i.e., convert, sugars, such as glucose, xylose, xylulose, arabinose, maltose, mannose, galactose, and/or oligosaccharides, directly or indirectly into the desired fermentation product. Examples of bacterial and fungal fermenting organisms producing ethanol are described by Lin et al., 2006 , Appl. Microbiol. Biotechnol. 69: 627-642.
Examples of fermenting microorganisms that can ferment hexose sugars include bacterial and fungal organisms, such as yeast. Yeast include strains of Candida, Kluyveromyces , and Saccharomyces , e.g., Candida sonorensis, Kluyveromyces marxianus , and Saccharomyces cerevisiae.
Examples of fermenting organisms that can ferment pentose sugars in their native state include bacterial and fungal organisms, such as some yeast. Xylose fermenting yeast include strains of Candida , preferably C. sheatae or C. sonorensis ; and strains of Pichia , e.g., P. stipitis , such as P. stipitis CBS 5773. Pentose fermenting yeast include strains of Pachysolen , preferably P. tannophilus . Organisms not capable of fermenting pentose sugars, such as xylose and arabinose, may be genetically modified to do so by methods known in the art.
Examples of bacteria that can efficiently ferment hexose and pentose to ethanol include, for example, Bacillus coagulans, Clostridium acetobutylicum, Clostridium thermocellum, Clostridium phytofermentans, Geobacillus sp., Thermoanaerobacter saccharolyticum , and Zymomonas mobilis (Philippidis, G. P., 1996, Cellulose bioconversion technology, in Handbook on Bioethanol: Production and Utilization , Wyman, C. E., ed., Taylor & Francis, Washington, D.C., 179-212).
Other fermenting organisms include strains of Bacillus , such as Bacillus coagulans; Candida , such as C. sonorensis, C. methanosorbosa, C. diddensiae, C. parapsilosis, C. naedodendra, C. blankii, C. entomophilia, C. brassicae, C. pseudotropicalis, C. boidinii, C. utilis , and C. scehatae; Clostridium , such as C. acetobutylicum, C. thermocellum , and C. phytofermentans; E. coli , especially E. coli strains that have been genetically modified to improve the yield of ethanol; Geobacillus sp.; Hansenula , such as Hansenula anomala; Klebsiella , such as K. oxytoca; Kluyveromyces , such as K. marxianus, K. lactis, K. thermotolerans , and K. fragilis; Schizosaccharomyces , such as S. pombe; Thermoanaerobacter , such as Thermoanaerobacter saccharolyticum ; and Zymomonas , such as Zymomonas mobilis.
Commercially available yeast suitable for ethanol production include, e.g., BIOFERM™ AFT and XR (NABC—North American Bioproducts Corporation, GA, USA), ETHANOL RED™ yeast (Fermentis/Lesaffre, USA), FALI™ (Fleischmann's Yeast, USA), FERMIOL™ (DSM Specialties), GERT STRAND™ (Gert Strand AB, Sweden), and SUPERSTART™ and THERMOSACC™ fresh yeast (Ethanol Technology, WI, USA).
In an aspect, the fermenting microorganism has been genetically modified to provide the ability to ferment pentose sugars, such as xylose utilizing, arabinose utilizing, and xylose and arabinose co-utilizing microorganisms.
The cloning of heterologous genes into various fermenting microorganisms has led to the construction of organisms capable of converting hexoses and pentoses to ethanol (co-fermentation) (Chen and Ho, 1993 , Appl. Biochem. Biotechnol. 39-40: 135-147; Ho et al., 1998 , Appl. Environ. Microbiol. 64: 1852-1859; Kotter and Ciriacy, 1993 , Appl. Microbiol. Biotechnol. 38: 776-783; Walfridsson et al., 1995 , Appl. Environ. Microbiol. 61: 4184-4190; Kuyper et al., 2004 , FEMS Yeast Research 4: 655-664; Beall et al., 1991 , Biotech. Bioeng. 38: 296-303; Ingram et al., 1998 , Biotechnol. Bioeng. 58: 204-214; Zhang et al., 1995 , Science 267: 240-243; Deanda et al., 1996 , Appl. Environ. Microbiol. 62: 4465-4470; WO 03/062430).
In one aspect, the fermenting organism comprises a polynucleotide encoding a variant of the present invention.
In another aspect, the fermenting organism comprises one or more polynucleotides encoding one or more cellulolytic enzymes, hemicellulolytic enzymes, and accessory enzymes described herein.
It is well known in the art that the organisms described above can also be used to produce other substances, as described herein.
The fermenting microorganism is typically added to the degraded cellulosic material or hydrolysate and the fermentation is performed for about 8 to about 96 hours, e.g., about 24 to about 60 hours. The temperature is typically between about 26° C. to about 60° C., e.g., about 32° C. or 50° C., and about pH 3 to about pH 8, e.g., pH 4-5, 6, or 7.
In one aspect, the yeast and/or another microorganism are applied to the degraded cellulosic material and the fermentation is performed for about 12 to about 96 hours, such as typically 24-60 hours. In another aspect, the temperature is preferably between about 20° C. to about 60° C., e.g., about 25° C. to about 50° C., about 32° C. to about 50° C., or about 32° C. to about 50° C., and the pH is generally from about pH 3 to about pH 7, e.g., about pH 4 to about pH 7. However, some fermenting organisms, e.g., bacteria, have higher fermentation temperature optima. Yeast or another microorganism is preferably applied in amounts of approximately 10 5 to 10 12 , preferably from approximately 10 7 to 10 10 , especially approximately 2×10 8 viable cell count per ml of fermentation broth. Further guidance in respect of using yeast for fermentation can be found in, e.g., “The Alcohol Textbook” (Editors K. Jacques, T. P. Lyons and D. R. Kelsall, Nottingham University Press, United Kingdom 1999), which is hereby incorporated by reference.
A fermentation stimulator can be used in combination with any of the processes described herein to further improve the fermentation process, and in particular, the performance of the fermenting microorganism, such as, rate enhancement and ethanol yield. A “fermentation stimulator” refers to stimulators for growth of the fermenting microorganisms, in particular, yeast. Preferred fermentation stimulators for growth include vitamins and minerals. Examples of vitamins include multivitamins, biotin, pantothenate, nicotinic acid, meso-inositol, thiamine, pyridoxine, para-aminobenzoic acid, folic acid, riboflavin, and Vitamins A, B, C, D, and E. See, for example, Alfenore et al., Improving ethanol production and viability of Saccharomyces cerevisiae by a vitamin feeding strategy during fed-batch process, Springer-Verlag (2002), which is hereby incorporated by reference. Examples of minerals include minerals and mineral salts that can supply nutrients comprising P, K, Mg, S, Ca, Fe, Zn, Mn, and Cu.
Fermentation Products:
A fermentation product can be any substance derived from the fermentation. The fermentation product can be, without limitation, an alcohol (e.g., arabinitol, n-butanol, isobutanol, ethanol, glycerol, methanol, ethylene glycol, 1,3-propanediol [propylene glycol], butanediol, glycerin, sorbitol, and xylitol); an alkane (e.g., pentane, hexane, heptane, octane, nonane, decane, undecane, and dodecane), a cycloalkane (e.g., cyclopentane, cyclohexane, cycloheptane, and cyclooctane), an alkene (e.g. pentene, hexene, heptene, and octene); an amino acid (e.g., aspartic acid, glutamic acid, glycine, lysine, serine, and threonine); a gas (e.g., methane, hydrogen (H 2 ), carbon dioxide (CO 2 ), and carbon monoxide (CO)); isoprene; a ketone (e.g., acetone); an organic acid (e.g., acetic acid, acetonic acid, adipic acid, ascorbic acid, citric acid, 2,5-diketo-D-gluconic acid, formic acid, fumaric acid, glucaric acid, gluconic acid, glucuronic acid, glutaric acid, 3-hydroxypropionic acid, itaconic acid, lactic acid, malic acid, malonic acid, oxalic acid, oxaloacetic acid, propionic acid, succinic acid, and xylonic acid); and polyketide.
In one aspect, the fermentation product is an alcohol. The term “alcohol” encompasses a substance that contains one or more hydroxyl moieties. The alcohol can be, but is not limited to, n-butanol, isobutanol, ethanol, methanol, arabinitol, butanediol, ethylene glycol, glycerin, glycerol, 1,3-propanediol, sorbitol, xylitol. See, for example, Gong et al., 1999, Ethanol production from renewable resources, in Advances in Biochemical Engineering/Biotechnology , Scheper, T., ed., Springer-Verlag Berlin Heidelberg, Germany, 65: 207-241; Silveira and Jonas, 2002 , Appl. Microbiol. Biotechnol. 59: 400-408; Nigam and Singh, 1995 , Process Biochemistry 30(2): 117-124; Ezeji et al., 2003 , World Journal of Microbiology and Biotechnology 19(6): 595-603.
In another aspect, the fermentation product is an alkane. The alkane may be an unbranched or a branched alkane. The alkane can be, but is not limited to, pentane, hexane, heptane, octane, nonane, decane, undecane, or dodecane.
In another aspect, the fermentation product is a cycloalkane. The cycloalkane can be, but is not limited to, cyclopentane, cyclohexane, cycloheptane, or cyclooctane.
In another aspect, the fermentation product is an alkene. The alkene may be an unbranched or a branched alkene. The alkene can be, but is not limited to, pentene, hexene, heptene, or octene.
In another aspect, the fermentation product is an amino acid. The organic acid can be, but is not limited to, aspartic acid, glutamic acid, glycine, lysine, serine, or threonine. See, for example, Richard and Margaritis, 2004 , Biotechnology and Bioengineering 87(4): 501-515.
In another aspect, the fermentation product is a gas. The gas can be, but is not limited to, methane, H 2 , CO 2 , or CO. See, for example, Kataoka et al., 1997 , Water Science and Technology 36(6-7): 41-47; and Gunaseelan, 1997 , Biomass and Bioenergy 13(1-2): 83-114.
In another aspect, the fermentation product is isoprene.
In another aspect, the fermentation product is a ketone. The term “ketone” encompasses a substance that contains one or more ketone moieties. The ketone can be, but is not limited to, acetone.
In another aspect, the fermentation product is an organic acid. The organic acid can be, but is not limited to, acetic acid, acetonic acid, adipic acid, ascorbic acid, citric acid, 2,5-diketo-D-gluconic acid, formic acid, fumaric acid, glucaric acid, gluconic acid, glucuronic acid, glutaric acid, 3-hydroxypropionic acid, itaconic acid, lactic acid, malic acid, malonic acid, oxalic acid, propionic acid, succinic acid, or xylonic acid. See, for example, Chen and Lee, 1997 , Appl. Biochem. Biotechnol. 63-65: 435-448.
In another aspect, the fermentation product is polyketide.
Recovery.
The fermentation product(s) can be optionally recovered from the fermentation medium using any method known in the art including, but not limited to, chromatography, electrophoretic procedures, differential solubility, distillation, or extraction. For example, alcohol is separated from the fermented cellulosic material and purified by conventional methods of distillation. Ethanol with a purity of up to about 96 vol. % can be obtained, which can be used as, for example, fuel ethanol, drinking ethanol, i.e., potable neutral spirits, or industrial ethanol.
Plants
The present invention also relates to isolated plants, e.g., a transgenic plant, plant part, or plant cell, comprising a polynucleotide of the present invention so as to express and produce a cellobiohydrolase variant in recoverable quantities. The variant may be recovered from the plant or plant part. Alternatively, the plant or plant part containing the variant may be used as such for improving the quality of a food or feed, e.g., improving nutritional value, palatability, and rheological properties, or to destroy an antinutritive factor.
The transgenic plant can be dicotyledonous (a dicot) or monocotyledonous (a monocot). Examples of monocot plants are grasses, such as meadow grass (blue grass, Poa), forage grass such as Festuca, Lolium , temperate grass, such as Agrostis , and cereals, e.g., wheat, oats, rye, barley, rice, sorghum, and maize (corn).
Examples of dicot plants are tobacco, legumes, such as lupins, potato, sugar beet, pea, bean and soybean, and cruciferous plants (family Brassicaceae), such as cauliflower, rape seed, and the closely related model organism Arabidopsis thaliana.
Examples of plant parts are stem, callus, leaves, root, fruits, seeds, and tubers as well as the individual tissues comprising these parts, e.g., epidermis, mesophyll, parenchyme, vascular tissues, meristems. Specific plant cell compartments, such as chloroplasts, apoplasts, mitochondria, vacuoles, peroxisomes and cytoplasm are also considered to be a plant part. Furthermore, any plant cell, whatever the tissue origin, is considered to be a plant part. Likewise, plant parts such as specific tissues and cells isolated to facilitate the utilization of the invention are also considered plant parts, e.g., embryos, endosperms, aleurone and seed coats.
Also included within the scope of the present invention are the progeny of such plants, plant parts, and plant cells.
The transgenic plant or plant cell expressing a variant may be constructed in accordance with methods known in the art. In short, the plant or plant cell is constructed by incorporating one or more expression constructs encoding a variant into the plant host genome or chloroplast genome and propagating the resulting modified plant or plant cell into a transgenic plant or plant cell.
The expression construct is conveniently a nucleic acid construct that comprises a polynucleotide encoding a variant operably linked with appropriate regulatory sequences required for expression of the polynucleotide in the plant or plant part of choice. Furthermore, the expression construct may comprise a selectable marker useful for identifying plant cells into which the expression construct has been integrated and DNA sequences necessary for introduction of the construct into the plant in question (the latter depends on the DNA introduction method to be used).
The choice of regulatory sequences, such as promoter and terminator sequences and optionally signal or transit sequences, is determined, for example, on the basis of when, where, and how the variant is desired to be expressed (Sticklen, 2008 , Nature Reviews 9: 433-443). For instance, the expression of the gene encoding a variant may be constitutive or inducible, or may be developmental, stage or tissue specific, and the gene product may be targeted to a specific tissue or plant part such as seeds or leaves. Regulatory sequences are, for example, described by Tague et al., 1988 , Plant Physiology 86: 506.
For constitutive expression, the 35S-CaMV, the maize ubiquitin 1, or the rice actin 1 promoter may be used (Franck et al., 1980 , Cell 21: 285-294; Christensen et al., 1992 , Plant Mol. Biol. 18: 675-689; Zhang et al., 1991 , Plant Cell 3: 1155-1165). Organ-specific promoters may be, for example, a promoter from storage sink tissues such as seeds, potato tubers, and fruits (Edwards and Coruzzi, 1990 , Ann. Rev. Genet. 24: 275-303), or from metabolic sink tissues such as meristems (Ito et al., 1994 , Plant Mol. Biol. 24: 863-878), a seed specific promoter such as the glutelin, prolamin, globulin, or albumin promoter from rice (Wu et al., 1998 , Plant Cell Physiol. 39: 885-889), a Vicia faba promoter from the legumin B4 and the unknown seed protein gene from Vicia faba (Conrad et al., 1998 , J. Plant Physiol. 152: 708-711), a promoter from a seed oil body protein (Chen et al., 1998 , Plant Cell Physiol. 39: 935-941), the storage protein napA promoter from Brassica napus , or any other seed specific promoter known in the art, e.g., as described in WO 91/14772. Furthermore, the promoter may be a leaf specific promoter such as the rbcs promoter from rice or tomato (Kyozuka et al., 1993 , Plant Physiol. 102: 991-1000), the chlorella virus adenine methyltransferase gene promoter (Mitra and Higgins, 1994 , Plant Mol. Biol. 26: 85-93), the aldP gene promoter from rice (Kagaya et al., 1995 , Mol. Gen. Genet. 248: 668-674), or a wound inducible promoter such as the potato pin2 promoter (Xu et al., 1993 , Plant Mol. Biol. 22: 573-588). Likewise, the promoter may be induced by abiotic treatments such as temperature, drought, or alterations in salinity or induced by exogenously applied substances that activate the promoter, e.g., ethanol, oestrogens, plant hormones such as ethylene, abscisic acid, and gibberellic acid, and heavy metals.
A promoter enhancer element may also be used to achieve higher expression of a variant in the plant. For instance, the promoter enhancer element may be an intron that is placed between the promoter and the polynucleotide encoding a variant. For instance, Xu et al., 1993, supra, disclose the use of the first intron of the rice actin 1 gene to enhance expression.
The selectable marker gene and any other parts of the expression construct may be chosen from those available in the art.
The nucleic acid construct is incorporated into the plant genome according to conventional techniques known in the art, including Agrobacterium -mediated transformation, virus-mediated transformation, microinjection, particle bombardment, biolistic transformation, and electroporation (Gasser et al., 1990 , Science 244: 1293; Potrykus, 1990 , Bio/Technology 8: 535; Shimamoto et al., 1989 , Nature 338: 274).
Agrobacterium tumefaciens -mediated gene transfer is a method for generating transgenic dicots (for a review, see Hooykas and Schilperoort, 1992 , Plant Mol. Biol. 19: 15-38) and for transforming monocots, although other transformation methods may be used for these plants. A method for generating transgenic monocots is particle bombardment (microscopic gold or tungsten particles coated with the transforming DNA) of embryonic calli or developing embryos (Christou, 1992 , Plant J. 2: 275-281; Shimamoto, 1994 , Curr. Opin. Biotechnol. 5: 158-162; Vasil et al., 1992 , Bio/Technology 10: 667-674). An alternative method for transformation of monocots is based on protoplast transformation as described by Omirulleh et al., 1993 , Plant Mol. Biol. 21: 415-428. Additional transformation methods include those described in U.S. Pat. Nos. 6,395,966 and 7,151,204 (both of which are herein incorporated by reference in their entirety).
Following transformation, the transformants having incorporated the expression construct are selected and regenerated into whole plants according to methods well known in the art. Often the transformation procedure is designed for the selective elimination of selection genes either during regeneration or in the following generations by using, for example, co-transformation with two separate T-DNA constructs or site specific excision of the selection gene by a specific recombinase.
In addition to direct transformation of a particular plant genotype with a construct of the present invention, transgenic plants may be made by crossing a plant having the construct to a second plant lacking the construct. For example, a construct encoding a variant can be introduced into a particular plant variety by crossing, without the need for ever directly transforming a plant of that given variety. Therefore, the present invention encompasses not only a plant directly regenerated from cells which have been transformed in accordance with the present invention, but also the progeny of such plants. As used herein, progeny may refer to the offspring of any generation of a parent plant prepared in accordance with the present invention. Such progeny may include a DNA construct prepared in accordance with the present invention. Crossing results in the introduction of a transgene into a plant line by cross pollinating a starting line with a donor plant line. Non-limiting examples of such steps are described in U.S. Pat. No. 7,151,204.
Plants may be generated through a process of backcross conversion. For example, plants include plants referred to as a backcross converted genotype, line, inbred, or hybrid.
Genetic markers may be used to assist in the introgression of one or more transgenes of the invention from one genetic background into another. Marker assisted selection offers advantages relative to conventional breeding in that it can be used to avoid errors caused by phenotypic variations. Further, genetic markers may provide data regarding the relative degree of elite germplasm in the individual progeny of a particular cross. For example, when a plant with a desired trait which otherwise has a non-agronomically desirable genetic background is crossed to an elite parent, genetic markers may be used to select progeny which not only possess the trait of interest, but also have a relatively large proportion of the desired germplasm. In this way, the number of generations required to introgress one or more traits into a particular genetic background is minimized.
The present invention also relates to methods of producing a variant of the present invention comprising: (a) cultivating a transgenic plant or a plant cell comprising a polynucleotide encoding the variant under conditions conducive for production of the variant; and optionally (b) recovering the variant.
The present invention may be further described by the following numbered paragraphs:
[1] A cellobiohydrolase variant, comprising deletions at two or more consecutive positions corresponding to positions of the B2-loop, wherein the variant has cellobiohydrolase activity, and wherein the variant has at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100%, sequence identity to the mature polypeptide of a parent cellobiohydrolase.
[2] A cellobiohydrolase variant, comprising a deletion at one or more positions corresponding to positions 195, 196, 197, and 198 of SEQ ID NO: 2, wherein the variant has cellobiohydrolase activity, and wherein the variant has at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100%, sequence identity to the mature polypeptide of a parent cellobiohydrolase.
[3] The variant of paragraph 1 or 2, wherein the parent cellobiohydrolase is selected from the group consisting of: (a) a polypeptide having at least 60% sequence identity to the mature polypeptide of SEQ ID NO: 2, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 14, SEQ ID NO: 16, SEQ ID NO: 18, SEQ ID NO: 20, or SEQ ID NO: 22; (b) a polypeptide encoded by a polynucleotide that hybridizes under low stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, or SEQ ID NO: 21; or the full-length complement thereof; (c) a polypeptide encoded by a polynucleotide having at least 60% identity to the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, or SEQ ID NO: 21; and (d) a fragment of the mature polypeptide of SEQ ID NO: 2, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 14, SEQ ID NO: 16, SEQ ID NO: 18, SEQ ID NO: 20, or SEQ ID NO: 22, which has cellobiohydrolase activity.
[4] The variant of paragraph 3, wherein the parent cellobiohydrolase has at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% sequence identity to the mature polypeptide of SEQ ID NO: 2, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 14, SEQ ID NO: 16, SEQ ID NO: 18, SEQ ID NO: 20, or SEQ ID NO: 22.
[5] The variant of paragraph 3 or 4, wherein the parent cellobiohydrolase is encoded by a polynucleotide that hybridizes under low stringency conditions, medium stringency conditions, medium-high stringency conditions, high stringency conditions, or very high stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, or SEQ ID NO: 21; or the full-length complement thereof.
[6] The variant of any of paragraphs 3-5, wherein the parent cellobiohydrolase is encoded by a polynucleotide having at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, or SEQ ID NO: 21.
[7] The variant of any of paragraphs 3-6, wherein the parent cellobiohydrolase comprises or consists of the mature polypeptide of SEQ ID NO: 2, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 14, SEQ ID NO: 16, SEQ ID NO: 18, SEQ ID NO: 20, or SEQ ID NO: 22.
[8] The variant of any of paragraphs 3-7, wherein the parent cellobiohydrolase is a fragment of the mature polypeptide of SEQ ID NO: 2, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 14, SEQ ID NO: 16, SEQ ID NO: 18, SEQ ID NO: 20, or SEQ ID NO: 22, wherein the fragment has cellobiohydrolase activity.
[9] The variant of any of paragraphs 1-8, which has at least 60%, e.g., at least 65%, at least 70%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 95% identity, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100%, sequence identity to the amino acid sequence of the parent cellobiohydrolase or the mature polypeptide thereof.
[10] The variant of any of paragraphs 1-9, wherein the number of alterations is 1-7, e.g., 1, 2, 3, 4, 5, 6, and 7 alterations.
[11] The variant of any of paragraphs 1, or 3-10, which comprises deletions at positions corresponding to positions 195 and 196 of SEQ ID NO: 2 (e.g., S195*+S196*, or S195*+A196*).
[12] The variant of any of paragraphs 1, or 3-10, which comprises deletions at positions corresponding to positions 196 and 197 of SEQ ID NO: 2 (e.g., S196*+N197*, or A196*+N197*)
[13] The variant of any of paragraphs 1, or 3-10, which comprises deletions at positions corresponding to positions 197 and 198 of SEQ ID NO: 2 (e.g., N197*+N198*, N197*+D198*).
[14] The variant of any of paragraphs 1, or 3-10, which comprises deletions at positions corresponding to positions 198 and 199 of SEQ ID NO: 2 (e.g., N198*+A199*, D198*+A199*, or D198*+P199*).
[15] The variant of any of paragraphs 1, or 3-10, which comprises deletions at positions corresponding to positions 199 and 200 of SEQ ID NO: 2 (e.g., A199*+N200*, or P199*+N200*).
[16] The variant of any of paragraphs 1, or 3-10, which comprises deletions at positions corresponding to positions 200 and 201 of SEQ ID NO: 2 (e.g., N200*+T201*, N200*+A201*, or N200*+S201*).
[17] The variant of any of paragraphs 1, or 3-10, which comprises deletions at three or more consecutive positions of the B2-loop (e.g., deletions at positions corresponding to positions 194*+195*+196*, 195*+196*+197*, 196*+197*+198*, 197*+198*+199*, 198*+199*+200*, or 199*+200*+201* of SEQ ID NO: 2).
[18] The variant of any of paragraphs 1, or 3-10, which comprises deletions at four or more consecutive positions of the B2-loop (e.g., deletions at positions corresponding to positions 194*+195*+196*+197*, 195*+196*+197*+198*, 196*+197*+198*+199*, 197*+198*+199*+200*, or 198*+199*+200*+201* of SEQ ID NO: 2).
[19] The variant of any of paragraphs 1, or 3-10, which comprises deletions at five or more consecutive positions of the B2-loop (e.g., deletions at positions corresponding to positions 194*+195*+196*+197*+198*, 195*+196*+197*+198*+199*, 196*+197*+198*+199*+200*, or 197*+198*+199*+200*+201* of SEQ ID NO: 2).
[20] The variant of any of paragraphs 1, or 3-10, which comprises deletions at six or more consecutive positions of the B2-loop. (e.g., deletions at positions corresponding to positions 194*+195*+196*+197*+198*+199*, 195*+196*+197*+198*+199*+200*, or 196*+197*+198*+199*+200*+201* of SEQ ID NO: 2).
[21] The variant of any of paragraphs 1, or 3-10, which comprises deletions at seven or more consecutive positions of the B2-loop (e.g., deletions at positions corresponding to positions 194*+195*+196*+197*+198*+199*+200*, or 195*+196*+197*+198*+199*+200*+201* of SEQ ID NO: 2).
[22] The variant of any of paragraphs 1, or 3-10, which comprises deletions at eight consecutive positions of the B2-loop (e.g., deletions at positions corresponding to positions 194*+195*+196*+197*+198*+199*+200*+201* of SEQ ID NO: 2).
[23] The variant of any of paragraphs 2-10, which comprises a deletion at a position corresponding to position 195 of SEQ ID NO: 2 (e.g., an S195* deletion).
[24] The variant of any of paragraphs 2-11, which comprises a deletion at a position corresponding to position 196 of SEQ ID NO: 2 (e.g., an S196* deletion).
[25] The variant of any of paragraphs 2-12, which comprises a deletion at a position corresponding to position 197 of SEQ ID NO: 2 (e.g., an N197* deletion).
[26] The variant of any of paragraphs 2-13, which comprises a deletion at a position corresponding to position 198 of SEQ ID NO: 2 (e.g., an N198* deletion).
[27] The variant of any of paragraphs 2-10, which comprises a deletion at two positions corresponding to any of positions 195, 196, 197, and 198 of SEQ ID NO: 2 (e.g., 195 and 196, such as S195*+S196*; 195 and 197, such as S195*+N197*; 195 and 198, such as S195*+N198*; 196 and 197, such as S196*+N197*; 196 and 198, such as S196*+N198*; or 197 and 198, such as N197*+N198*
[28] The variant of any of paragraphs 2-10, which comprises a deletion at positions corresponding to positions 196, 197, and 198 of SEQ ID NO: 2 (e.g., S196*+N197*+N198*).
[29] The variant of any of paragraphs 2-10, which comprises a deletion at each position corresponding to positions 195, 196, 197, and 198 of SEQ ID NO: 2 (e.g., S195*+S196*+N197*+N198*).
[30] The variant of any of paragraphs 1-29, wherein the variant further comprises an alteration (e.g., a substitution) at one or more positions corresponding to positions 197, 198, and 199 of SEQ ID NO: 2
[31] The variant of any of paragraphs 1-30, wherein the variant further comprises a deletion at a position corresponding to position 200 of SEQ ID NO: 2.
[32] The variant of paragraph 1 or 2, which comprises or consists of amino acids 1-434 of SEQ ID NO: 78, amino acids 1-495 of SEQ ID NO: 80, amino acids 1-495 of SEQ ID NO: 82, or amino acids 1-503 of SEQ ID NO: 95.
[33] The variant of any of paragraphs 1-31, wherein the parent is a hybrid or chimeric polypeptide in which the carbohydrate binding domain of the parent is replaced with a different carbohydrate binding domain.
[34] The variant of any of paragraphs 1-31, which is a hybrid or chimeric polypeptide in which the carbohydrate binding domain of the variant is replaced with a different carbohydrate binding domain.
[35] The variant of any of paragraphs 1-31, wherein the parent is a fusion protein in which a heterologous carbohydrate binding domain is fused to the parent.
[36] The variant of paragraph 35, wherein the carbohydrate binding domain is fused to the N-terminus or the C-terminus of the parent.
[37] The variant of paragraph 35 or 36, wherein the fusion protein comprises or consists of SEQ ID NO: 78 or the mature polypeptide thereof.
[38] The variant of any of paragraphs 1-31, which is a fusion protein in which a heterologous carbohydrate binding domain is fused to the variant.
[39] The variant of paragraph 38, wherein the carbohydrate binding domain is fused to the N-terminus or the C-terminus of the variant.
[40] The variant of paragraph 38 or 39, which comprises or consists of SEQ ID NO: 78 or the mature polypeptide thereof.
[41] The variant of any of paragraphs 1-40, which has an increased specific performance relative to the parent.
[42] The variant of any of paragraphs 1-41, which is isolated.
[43] An isolated polynucleotide encoding the variant of any of paragraphs 1-42.
[44] A nucleic acid construct or expression vector comprising the polynucleotide of paragraph 43.
[45] A host cell comprising the polynucleotide of paragraph 43.
[46] A method of producing a cellobiohydrolase variant, comprising: cultivating the host cell of paragraph 45 under conditions suitable for expression of the variant.
[47] The method of paragraph 46, further comprising recovering the variant.
[48] A transgenic plant, plant part or plant cell transformed with the polynucleotide of paragraph 43.
[49] A method of producing the variant of any of paragraphs 1-42, comprising: cultivating a transgenic plant or a plant cell comprising a polynucleotide encoding the variant under conditions conducive for production of the variant.
[50] The method of paragraph 49, further comprising recovering the variant
[51] A method for obtaining a cellobiohydrolase variant, comprising introducing into a parent cellobiohydrolase deletions at two or more consecutive positions of the B2-loop, wherein the variant has cellobiohydrolase activity.
[52] A method for obtaining a cellobiohydrolase variant, comprising introducing into a parent cellobiohydrolase a deletion at one or more positions corresponding to positions 195, 196, 197, and 198, of SEQ ID NO: 2, wherein the variant has cellobiohydrolase activity.
[53] The method of paragraph 51 or 52, further comprising recovering the variant.
[54] A composition comprising the variant of any of paragraphs 1-42.
[55] A whole broth formulation or cell culture composition comprising the variant of any of paragraphs 1-42.
[56] A process for degrading a cellulosic material, comprising: treating the cellulosic material with an enzyme composition in the presence of the variant of any of paragraphs 1-42.
[57] The process of paragraph 56, wherein the cellulosic material is pretreated.
[58] The process of paragraph 56 or 57, wherein the enzyme composition comprises one or more enzymes selected from the group consisting of a cellulase, a GH61 polypeptide having cellulolytic enhancing activity, a hemicellulase, a catalase, an esterase, an expansin, a laccase, a ligninolytic enzyme, a pectinase, a peroxidase, a protease, and a swollenin.
[59] The process of paragraph 58, wherein the cellulase is one or more enzymes selected from the group consisting of an endoglucanase, a cellobiohydrolase, and a beta-glucosidase.
[60] The process of paragraph 58, wherein the hemicellulase is one or more enzymes selected from the group consisting of a xylanase, an acetylxylan esterase, a feruloyl esterase, an arabinofuranosidase, a xylosidase, and a glucuronidase.
[61] The process of any of paragraphs 56-60, further comprising recovering the degraded cellulosic material.
[62] The process of paragraph 61, wherein the degraded cellulosic material is a sugar.
[63] The process of paragraph 62, wherein the sugar is selected from the group consisting of glucose, xylose, mannose, galactose, and arabinose.
[64] A process for producing a fermentation product, comprising: (a) saccharifying a cellulosic material with an enzyme composition in the presence of the variant of any of paragraphs 1-42; (b) fermenting the saccharified cellulosic material with one or more fermenting microorganisms to produce the fermentation product; and (c) recovering the fermentation product from the fermentation.
[65] The process of paragraph 64, wherein the cellulosic material is pretreated.
[66] The process of paragraph 64 or 65, wherein the enzyme composition comprises the enzyme composition comprises one or more enzymes selected from the group consisting of a cellulase, a GH61 polypeptide having cellulolytic enhancing activity, a hemicellulase, a catalase, an esterase, an expansin, a laccase, a ligninolytic enzyme, a pectinase, a peroxidase, a protease, and a swollenin.
[67] The process of paragraph 66, wherein the cellulase is one or more enzymes selected from the group consisting of an endoglucanase, a cellobiohydrolase, and a beta-glucosidase.
[68] The process of paragraph 66, wherein the hemicellulase is one or more enzymes selected from the group consisting of a xylanase, an acetylxylan esterase, a feruloyl esterase, an arabinofuranosidase, a xylosidase, and a glucuronidase.
[69] The process of any of paragraphs 64-68, wherein steps (a) and (b) are performed simultaneously in a simultaneous saccharification and fermentation.
[70] The process of any of paragraphs 64-69, wherein the fermentation product is an alcohol, an alkane, a cycloalkane, an alkene, an amino acid, a gas, isoprene, a ketone, an organic acid, or polyketide.
[71] A process of fermenting a cellulosic material, comprising: fermenting the cellulosic material with one or more fermenting microorganisms, wherein the cellulosic material is saccharified with an enzyme composition in the presence of the variant of any of paragraphs 1-42.
[72] The process of paragraph 71, wherein the fermenting of the cellulosic material produces a fermentation product.
[73] The process of paragraph 72, further comprising recovering the fermentation product from the fermentation.
[74] The process of paragraph 72 or 73, wherein the fermentation product is an alcohol, an alkane, a cycloalkane, an alkene, an amino acid, a gas, isoprene, a ketone, an organic acid, or polyketide.
[75] The process of any of paragraphs 71-74, wherein the cellulosic material is pretreated before saccharification.
[76] The process of any of paragraphs 71-75, wherein the enzyme composition comprises one or more enzymes selected from the group consisting of a cellulase, a GH61 polypeptide having cellulolytic enhancing activity, a hemicellulase, a catalase, an esterase, an expansin, a laccase, a ligninolytic enzyme, a pectinase, a peroxidase, a protease, and a swollenin.
[77] The process of paragraph 76, wherein the cellulase is one or more enzymes selected from the group consisting of an endoglucanase, a cellobiohydrolase, and a beta-glucosidase.
[78] The process of paragraph 77, wherein the hemicellulase is one or more enzymes selected from the group consisting of a xylanase, an acetylxylan esterase, a feruloyl esterase, an arabinofuranosidase, a xylosidase, and a glucuronidase.
The present invention is further described by the following examples that should not be construed as limiting the scope of the invention.
Examples
Strains
Aspergillus oryzae strain MT3568 was used as a host for expression of the Trichoderma reesei gene encoding cellobiohydrolase I and a variant thereof. A. oryzae MT3568 is an amdS (acetamidase) disrupted gene derivative of Aspergillus oryzae JaL355 (WO 2002/40694) in which pyrG auxotrophy was restored by disrupting the A. oryzae acetamidase (amdS) gene.
Media and Solutions
COVE sucrose plates or slants were composed of 342 g of sucrose, 20 g of agar powder, 20 ml of COVE salt solution, and deionized water to 1 liter. The medium was sterilized by autoclaving at 15 psi for 15 minutes (Bacteriological Analytical Manual, 8th Edition, Revision A, 1998). The medium was cooled to 60° C. and then acetamide to 10 mM, CsCl to 15 mM, and TRITON® X-100 (50 μl/500 ml) were added.
COVE salt solution was composed of 26 g of MgSO 4 .7H 2 O, 26 g of KCl, 26 g of KH 2 PO 4 , 50 ml of COVE trace metals solution, and deionized water to 1 liter.
COVE trace metals solution was composed of 0.04 g of Na 2 B 4 O 7 .10H 2 O, 0.4 g of CuSO 4 .5H 2 O, 1.2 g of FeSO 4 .7H 2 O, 0.7 g of MnSO 4 .H 2 O, 0.8 g of Na 2 MoO 4 .2H 2 O, 10 g of ZnSO 4 .7H 2 O, and deionized water to 1 liter.
DAP-4C medium was composed of 20 g of dextrose, 10 g of maltose, 11 g of MgSO 4 .7H 2 O, 1 g of KH 2 PO 4 , 2 g of citric acid, 5.2 g of K 3 PO 4 .H 2 O, 0.5 g of yeast extract (Difco), 1 ml of antifoam, 0.5 ml of KU6 trace metals solution, 2.5 g of CaCO 3 , and deionized water to 1 liter. The medium was sterilized by autoclaving at 15 psi for 15 minutes (Bacteriological Analytical Manual, 8th Edition, Revision A, 1998). Before use, 3.5 ml of sterile 50% (NH 4 ) 2 HPO 4 and 5 ml of sterile 20% lactic acid were added per 150 ml.
G2-Gly medium was composed of 18 g of yeast extract, 24 g of glycerol (86-88%), 1 ml of antifoam, and deionized water to 1 liter.
KU6 trace metals solution was composed of 0.13 g of NiCl 2 , 2.5 g of CuSO 4 .5H 2 O, 13.9 g of FeSO 4 .7H 2 O, 8.45 g of MnSO 4 .H 2 O, 6.8 g of ZnCl 2 , 3 g of citric acid, and deionized water to 1 liter.
LB medium was composed of 10 g of Bacto-Tryptone, 5 g of yeast extract, 10 g of sodium chloride, and deionized water to 1 liter.
LB plates were composed of 10 g of Bacto-Tryptone, 5 g of yeast extract, 10 g of sodium chloride, 15 g of Bacto-agar, and deionized water to 1 liter.
PDA plates were composed of potato infusion made by boiling 300 g of sliced (washed but unpeeled) potatoes in water for 30 minutes and then decanting or straining the broth through cheesecloth. Distilled water was then added until the total volume of the suspension was 1 liter. Then 20 g of dextrose and 20 g of agar powder were added. The medium was sterilized by autoclaving at 15 psi for 15 minutes (Bacteriological Analytical Manual, 8th Edition, Revision A, 1998).
TAE buffer was composed of 40 mM Tris base, 20 mM sodium acetate, and 1 mM disodium EDTA.
YP+2% glucose medium was composed of 1% yeast extract, 2% peptone, and 2% glucose in deionized water.
YP+2% maltose medium was composed of 10 g of yeast extract, 20 g of peptone, 20 g of maltose, and deionized water to 1 liter.
Example 1: Source of DNA Sequence Information for Trichoderma reesei Cellobiohydrolase I
The genomic DNA sequence and deduced amino acid sequence of the Trichoderma reesei GH7 cellobiohydrolase I gene is shown in SEQ ID NO: 1 and SEQ ID NO: 2, respectively. Genomic sequence information was generated by the U.S. Department of Energy Joint Genome Institute (JGI) and published by Martinez et al., 2008 , Nature Biotechnology 26 (5): 553-560. The amino acid sequence of the full-length cellobiohydrolase I is publicly available from the National Center for Biotechnology Information (NCBI) and annotated as GenBank: EGR44817.1 (SEQ ID NO: 2). The cDNA sequence and deduced amino acid sequence of the Trichoderma reesei cellobiohydrolase I gene is shown in SEQ ID NO: 3 and SEQ ID NO: 2, respectively.
Based on the publicly available amino acid sequence, a codon-optimized synthetic gene encoding the full-length cellobiohydrolase I was generated for Aspergillus oryzae expression based on the algorithm developed by Gustafsson et al., 2004 , Trends in Biotechnology 22 (7): 346-353. The codon-optimized coding sequence (SEQ ID NO: 4) was synthesized by the GENEART® Gene Synthesis service (Life Technologies Corp., San Diego. Calif., USA) with a 5′ Bam HI restriction site, a 3′ Hind III restriction site, and a Kozac consensus sequence (CACC) situated between the start codon and the Bam HI restriction site.
Example 2: Site-Directed Mutagenesis of the Trichoderma reesei Cellobiohydrolase I
The codon-optimized synthetic gene encoding the T. reesei cellobiohydrolase I was provided in a non-specified kanamycin-resistant E. coli cloning vector. To generate the T. reesei cellobiohydrolase I M6 variant (SEQ ID NO: 5 for the mutant DNA sequence and SEQ ID NO: 6 for the variant), an AAC codon (N197) was replaced with a GCC codon (197A) and an AAC codon (N200) was replaced with a GCC codon (200A). Two synthetic primers for site-directed mutagenesis were designed as shown below using the QUIKCHANGE® Primer Design (Agilent Technologies, Inc., Wilmington, Del., USA) online tool to introduce the site-directed mutations changing an AAC codon (N197) to a GCC codon (197A) and an AAC codon (N200) to a GCC codon (200A).
Site-directed mutagenesis of the synthetic gene encoding the wild-type T. reesei cellobiohydrolase was facilitated by two PCR amplifications of the kanamycin-resistant E. coli cloning vector provided by GENEART® Gene Synthesis using the primers and procedure described below:
Primer F-N197A:
(SEQ ID NO: 23)
5′-GGGAACCCTCGTCGGCCAACGCCAACACCG-3′
Primer R-N197A:
(SEQ ID NO: 24)
5′-CGGTGTTGGCGTTGGCCGACGAGGGTTCCC-3′
Primer F-N200A:
(SEQ ID NO: 25)
5′-TCGTCGGCCAACGCCGCCACCGGCATTGGAGG-3′
Primer R-N200A:
(SEQ ID NO: 26)
5′-CCTCCAATGCCGGTGGCGGCGTTGGCCGACGA-3′
The two mutations were introduced consecutively by PCR using a PHUSION® High-Fidelity PCR Kit (Finnzymes Oy, Espoo, Finland). The PCR solution was composed of 10 μl of 5× HF buffer (Finnzymes Oy, Espoo, Finland), 1 μl of dNTPs (10 mM), 0.5 μl of PHUSION® DNA polymerase (0.2 units/μl) (Finnzymes Oy, Espoo, Finland), 2.5 μl of primer F-N197A (10 μM), 2.5 μl of primer R-N197A (10 μM), 1 μl of template DNA (GENEART® vector, 10 ng/μl), and 32.5 μl of deionized water in a total volume of 50 μl. The PCR was performed using a PTC-200 DNA Engine (MJ Research Inc., Waltham, Mass., USA) programmed for 1 cycle at 98° C. for 30 seconds; and 16 cycles each at 98° C. for 30 seconds, 55° C. for 1 minute, and 72° C. for 4 minutes. The PCR solution was then held at 15° C. until removed from the PCR machine.
Following PCR, 10 units of Dpn I were added directly to the PCR solution and incubated at 37° C. for 1 hour. Then 1 μl of the Dpn I treated PCR solution was transformed into ONE SHOT® TOP10F′ Chemically Competent E. coli cells (Invitrogen, Carlsbad, Calif., USA) according to the manufacturer's protocol and spread onto LB plates supplemented with 0.05 mg of kanamycin per ml. After incubation at 37° C. overnight, transformants were observed growing under selection on the LB kanamycin plates. Two transformants were cultivated in LB medium supplemented with 0.05 mg of kanamycin per ml and plasmids were isolated using a QIAPREP® Spin Miniprep Kit (QIAGEN Inc., Valencia, Calif., USA).
The isolated plasmids were sequenced using an Applied Biosystems 3730xl DNA Analyzer (Applied Biosystems, Foster City, Calif., USA) with vector primers and a T. reesei cellobiohydrolase I gene specific primer (R-Central), shown below, in order to determine a representative plasmid that was free of PCR errors and contained the AAC to GCC mutation.
Primer F-vector:
(SEQ ID NO: 27)
5′-CGTTGTAAAACGACGGCC-3′
Primer R-vector:
(SEQ ID NO: 28)
5′-TGTTAATGCAGCTGGCAC-3′
Primer R-Central:
(SEQ ID NO: 29)
5′-CTTGTCGGAGAACGACGA-3′
One plasmid clone free of PCR errors and containing the AAC (N197) to GCC (197A) mutation was chosen and designated plasmid pN197A.
A second round of PCR was performed to introduce the N200A mutation by PCR using a PHUSION® High-Fidelity PCR Kit. The PCR solution was composed of 10 μl of 5× HF buffer, 1 μl of dNTPs (10 mM), 0.5 μl of PHUSION® DNA polymerase (0.2 units/μl), 2.5 μl of primer F-N200A (10 μM), 2.5 μl of primer R-N200A (10 μM), 1 μl of template DNA (pN197A, 10 ng/μl), and 32.5 μl of deionized water in a total volume of 50 μl. The PCR was performed using a PTC-200 DNA Engine programmed for 1 cycle at 98° C. for 30 seconds; and 16 cycles each at 98° C. for 30 seconds, 55° C. for 1 minute, and 72° C. for 4 minutes. The PCR solution was then held at 15° C. until removed from the PCR machine.
Following PCR, 10 units of Dpn I were added directly to the PCR solution and incubated at 37° C. for 1 hour. Then 1 μl of the Dpn I treated PCR solution was transformed into ONE SHOT® TOP10F′ Chemically Competent E. coli cells according to the manufacturer's protocol and spread onto LB plates supplemented with 0.05 mg of kanamycin per ml. After incubation at 37° C. overnight, transformants were observed growing under selection on the LB kanamycin plates. Two transformants were cultivated in LB medium supplemented with 0.05 mg of kanamycin per ml and plasmids were isolated using a QIAPREP® Spin Miniprep Kit.
The isolated plasmids were sequenced using an Applied Biosystems 3730xl DNA Analyzer with primers F-vector, R-vector, and R-Central shown above in order to determine a representative plasmid that was free of PCR errors and contained the AAC to GCC mutation.
One plasmid clone free of PCR errors and containing the AAC (N197) to GCC (197A) and ACC (N200) to GCC (200A) mutations was chosen and designated plasmid pM6. The variant is designated herein as “M6 variant”.
Example 3: Construction of an Aspergillus oryzae Expression Vector Containing a Trichoderma reesei cDNA Sequence Encoding Cellobiohydrolase I
The kanamycin-resistant E. coli cloning vector provided by GENEART® Gene Synthesis encoding the T. reesei cellobiohydrolase I (SEQ ID NO: 4) was digested with Fast Digest Bam HI and Hind III (Fermentas Inc., Glen Burnie, Md., USA) according to manufacturer's instructions. The reaction products were isolated by 1.0% agarose gel electrophoresis using TAE buffer where a 1552 bp product band was excised from the gel and purified using an ILLUSTRA™ GFX™ DNA Purification Kit (GE Healthcare Life Sciences, Brondby, Denmark).
The 1552 bp fragment was then cloned into pDau109 (WO 2005/042735) digested with Bam HI and Hind III using T4 DNA ligase (New England Biolabs, Ipswich, Mass., USA). The Bam HI-Hind III digested pDau109 and the Bam HI/Hind III fragment containing the T. reesei cellobiohydrolase I coding sequence were mixed in a molar ratio of 1:3 (i.e., mass ratio approximately 2.5:1 or 20 ng:50 ng) and ligated with 50 units of T4 DNA ligase in 1× T4 DNA ligase buffer (New England Biolabs, Ipswich, Mass., USA) with 1 mM ATP at 16° C. over-night in accordance with the manufacturer's instructions. Cloning of the T. reesei cellobiohydrolase I gene into the Bam HI-Hind III digested pDau109 resulted in transcription of the T. reesei cellobiohydrolase I gene under the control of a NA2-tpi double promoter. The NA2-tpi promoter is a modified promoter from the gene encoding the Aspergillus niger neutral alpha-amylase in which the untranslated leader has been replaced by an untranslated leader from the gene encoding the Aspergillus nidulans triose phosphate isomerase.
The ligation mixture was transformed into ONE SHOT® TOP10F′ Chemically Competent E. coli cells according to the manufacturer's protocol and spread onto LB plates supplemented with 0.1 mg of ampicillin per ml. After incubation at 37° C. overnight, colonies were observed growing under selection on the LB ampicillin plates
Insertion of the T. reesei cellobiohydrolase I gene into pDau109 was verified by PCR on colonies as described below using the following primers.
Primer F-pDau109
(SEQ ID NO: 30)
5′-CCCTTGTCGATGCGATGTATC-3′
Primer R-pDau109
(SEQ ID NO: 31)
5′-ATCCTCAATTCCGTCGGTCGA-3′
A 1.1× REDDYMIX® Master Mix (Thermo Fisher Scientific, Roskilde, Denmark) was used for the PCR. The PCR solution was composed of 10 μl of 1.1× REDDYMIX® Master Mix, 0.5 μl of primer F-pDau109 (10 μM), and 0.5 μl of primer R-pDau109 (10 μM). A toothpick was used to transfer a small amount of cells to the PCR solution. The PCR was performed using a PTC-200 DNA Engine programmed for 1 cycle at 94° C. for 3 minutes; 30 cycles each at 94° C. for 30 seconds, 50° C. for 1 minute, and 72° C. for 2 minutes; and 1 cycle at 72° C. for 1 minute. The PCR solution was then held at 15° C. until removed from the PCR machine.
The PCR products were analyzed by 1.0% agarose gel electrophoresis using TAE buffer where a 1860 bp PCR product band was observed confirming insertion of the T. reesei cellobiohydrolase I coding sequence into pDau109.
An E. coli transformant containing the T. reesei cellobiohydrolase I plasmid construct was cultivated in LB medium supplemented with 0.1 mg of ampicillin per ml and plasmid DNA was isolated using a QIAPREP® Spin Miniprep Kit. The plasmid was designated pKHJN0036.
Example 4: Construction of an Aspergillus oryzae Expression Vector Containing Trichoderma reesei cDNA Sequence Encoding the Cellobiohydrolase I M6 Variant
Plasmid pM6 encoding the T. reesei cellobiohydrolase I M6 variant was digested with Fast Digest Bam HI and Hind III according to manufacturer's instructions. The reaction products were isolated by 1.0% agarose gel electrophoresis using TAE buffer where a 1552 bp product band was excised from the gel and purified using an ILLUSTRA™ GFX™ DNA Purification Kit.
The 1552 bp fragment was then cloned into pDau109 digested with Bam HI and Hind III using T4 DNA ligase. The Bam HI-Hind III digested pDau109 and the Bam HI/Hind III fragment containing the T. reesei cellobiohydrolase I M6 variant coding sequence were mixed in a molar ratio of 1:3 (i.e., mass ratio approximately 2.5:1 or 20 ng:50 ng) and ligated with 50 units of T4 DNA ligase in 1× T4 DNA ligase buffer with 1 mM ATP at 16° C. overnight. Cloning of the T. reesei cellobiohydrolase I M6 variant gene into the Bam HI-Hind III digested pDau109 resulted in transcription of the T. reesei cellobiohydrolase I M6 variant gene under the control of a NA2-tpi double promoter described above.
The ligation mixture was transformed into ONE SHOT® TOP10F′ Chemically Competent E. coli cells according to the manufacturer's protocol and spread onto LB plates supplemented with 0.1 mg of ampicillin per ml. After incubation at 37° C. overnight, colonies were observed growing under selection on the LB ampicillin plates
Insertion of the T. reesei cellobiohydrolase I M6 variant gene into pDau109 was verified by PCR on colonies as described below using primers F-pDau109 and R-pDau109 (Example 3) shown below.
Primer F-pDau109
(SEQ ID NO: 30)
5′-CCCTTGTCGATGCGATGTATC-3′
Primer R-pDau109
(SEQ ID NO: 31)
5′-ATCCTCAATTCCGTCGGTCGA-3′
A 1.1× REDDYMIX® Master Mix was used for the PCR. The PCR solution was composed of 10 μl of 1.1× REDDYMIX® Master Mix, 0.5 μl of primer F-pDau109 (10 μM), and 0.5 μl of primer R-pDau109 (10 μM). A toothpick was used to transfer a small amount of cells to the PCR solution. The PCR was performed using a PTC-200 DNA Engine programmed for 1 cycle at 94° C. for 3 minutes; 30 cycles each at 94° C. for 30 seconds, 50° C. for 1 minute, and 72° C. for 2 minutes; and 1 cycle at 72° C. for 1 minute. The PCR solution was then held at 15° C. until removed from the PCR machine.
The PCR reaction products were analyzed by 1.0% agarose gel electrophoresis using TAE buffer where a 1860 bp PCR product band was observed confirming insertion of the T. reesei cellobiohydrolase I M6 variant coding sequence into pDau109.
An E. coli transformant containing the T. reesei cellobiohydrolase I M6 variant plasmid construct was cultivated in LB medium supplemented with 0.1 mg of ampicillin per ml and plasmid was isolated using a QIAPREP® Spin Miniprep Kit. The plasmid was designated pKHJN0059.
Example 5: Expression of the Wild-Type Trichoderma reesei Cellobiohydrolase I
The expression plasmid pKHJN0036 was transformed into Aspergillus oryzae MT3568 protoplasts according to Christensen et al., 1988 , Biotechnology 6, 1419-1422 and WO 2004/032648. A. oryzae MT3568 protoplasts were prepared according to the method of EP 0238023 B1, pages 14-15.
Transformants were purified on COVE sucrose plates through single conidia prior to sporulating them on PDA plates. Spores of the transformants were inoculated into 96 deep well plates containing 0.75 ml of YP+2% glucose medium and incubated stationary at 30° C. for 4 days. Production of the T. reesei cellobiohydrolase I by the transformants was analyzed from culture supernatants of the 96 deep well cultivations. Expression was verified by SDS-PAGE analysis using an E-Page 8% SDS-PAGE 48 well gel (Invitrogen, Carlsbad, Calif., USA) and Coomassie blue staining. Based on the level of expression by SDS-PAGE, one transformant was selected and designated Aspergillus oryzae CBH I.
For larger scale production, A. oryzae CBH I spores were spread onto COVE sucrose slants and incubated for five days at 37° C. The confluent spore slants were washed twice with 5 ml of 0.01% TWEEN® 20 to maximize the number of spores collected. The spore suspensions were then used to inoculate seven 500 ml flasks containing 150 ml of DAP-4C medium. The cultures were incubated at 30° C. with constant shaking at 100 rpm. At day four post-inoculation, the culture broths were collected by filtration through a bottle top MF75 Supor MachV 0.2 μm PES filter (Thermo Fisher Scientific, Roskilde, Denmark). Expression was verified by SDS-PAGE analysis using an E-Page 8% SDS-PAGE 48 well gel and Coomassie staining. The culture broths from A. oryzae CBH I produced a band at approximately 80 kDa for the T. reesei cellobiohydrolase I.
Example 6: Expression of the Trichoderma reesei Cellobiohydrolase I M6 Variant
The expression plasmid pKHJN0059 was transformed into Aspergillus oryzae MT 3568 protoplasts according to Christensen et al., 1988, supra and WO 2004/032648. A. oryzae MT3568 protoplasts were prepared according to the method of European Patent, EP0238023, pages 14-15.
Transformants were purified on COVE sucrose plates through single conidia prior to sporulating them on PDA plates. Spores of the transformants were inoculated into 96 deep well plates containing 0.75 ml of YP+2% glucose medium and incubated stationary at 30° C. for 4 days. Production of the T. reesei cellobiohydrolase I M6 variant by the transformants was analyzed from culture supernatants of the 96 deep well cultivations. Expression was verified by SDS-PAGE analysis using an E-Page 8% SDS-PAGE 48 well gel and Coomassie staining. Based on the level of expression by SDS-PAGE, one transformant was selected for further work and designated Aspergillus oryzae M6.
For larger scale production, A. oryzae M6 spores were spread onto COVE sucrose slants and incubated for five days at 37° C. The confluent spore slants were washed twice with 5 ml of 0.01% TWEEN® 20 to maximize the number of spores collected. The spore suspensions were then used to inoculate seven 500 ml flasks containing 150 ml of DAP-4C medium. The cultures were incubated at 30° C. with constant shaking at 100 rpm. At day four post-inoculation, the culture broths were collected by filtration through a bottle top MF75 Supor MachV 0.2 μm PES filter. Expression was verified by SDS-PAGE analysis using an E-Page 8% SDS-PAGE 48 well gel and Coomassie staining. The culture broths from A. oryzae M6 produced a band at approximately 80 kDa for the T. reesei cellobiohydrolase I M6 variant.
Example 7: Purification of the Trichoderma reesei Wild-Type Cellobiohydrolase I and Cellobiohydrolase I M6 Variant
The filtered broths of A. oryzae CBH I (Example 5) and A. oryzae M6 (Example 6) were adjusted to pH 7.0 and filtered using a 0.22 μm PES filter (Nalge Nunc International Corp., Rochester, N.Y., USA). Then ammonium sulphate was added to each filtrate to a concentration of 1.8 M.
Each filtrate was purified according to the following procedure. The filtrate was loaded onto a Phenyl SEPHAROSE® 6 Fast Flow column (high sub) (GE Healthcare, United Kingdom) equilibrated with 1.8 M ammonium sulphate, 25 mM HEPES pH 7.0. After a wash with 0.54 M ammonium sulphate, the bound proteins were batch eluted with 25 mM HEPES pH 7.0. Fractions were collected and analyzed by SDS-PAGE using 12-well NUPAGE® 4-12% Bis-Tris gel (GE Healthcare, Piscataway, N.J., USA). The fractions were pooled based on SDS-PAGE as above and applied to a SEPHADEX™ G-25 (medium) column (GE Healthcare, United Kingdom) equilibrated with 25 mM MES pH 6.0. Fractions were collected, analyzed by SDS-PAGE as above, and pooled. The pooled fractions were applied to a 6 ml RESOURCE™ 15Q column (GE Healthcare, United Kingdom) equilibrated with 25 mM MES pH 6.0 and bound proteins were eluted with a linear 0-300 mM sodium chloride gradient (12 column volumes) for the wild-type cellobiohydrolase or a linear 0-350 mM sodium chloride gradient (14 column volumes) for the variant. Fractions were collected and analyzed by SDS-PAGE, A 280 , and activity measurements using 4-nitrophenyl-beta-D-glucopyranoside (Sigma Chemical Co., St. Louis, Mo., USA) and 4-nitrophenyl-beta-D-lactopyranoside (Sigma Chemical Co., St. Louis, Mo., USA) as substrates. The assays were performed in 96-well Nunc microtiter plates (Thermo Scientific, Sunnyvale, Calif., USA). The assay buffer was 50 mM Britton-Robinson buffer (50 mM H 3 PO 4 , 50 mM CH 3 COOH, 50 mM H 3 BO 3 ) with 50 mM KCl, 1 mM CaCl 2 , 0.01% TRITON® X-100, pH adjusted to 6.0 with NaOH. A 20 μl sample of protein solution was pipetted into each well and 120 μl of 1 mM substrate in the assay buffer were added. The substrate 4-nitrophenyl-beta-D-glucopyranoside was used to determine beta-glucosidase activity and 4-nitrophenyl-beta-D-lactopyranoside for cellobiohydrolase I and cellobiohydrolase variant activity. A standard curve was made by replacing the protein solution with 20 μl of 4-nitrophenolate standard (0, 0.05, 0.075, 0.1, 0.2, 0.3, 0.4, 0.5 mM). If necessary, samples were diluted in the assay buffer to yield absorptions within the range of the standard curve. The plate was sealed and incubated in a thermomixer at 37° C. for 15 minutes with 750 rpm shaking. Immediately after incubation the reaction was stopped by adding 100 μl of 0.5 M glycine-2 mM EDTA pH 10 and the absorption was measured at 405 nm. The absorption of a “blank”, in which the protein was added after the stop solution, was recorded for each sample and subtracted from the result to obtain the absorption of released 4-nitrophenolate.
Based on SDS-PAGE, A 280 , and the activity measurements, the fractions were pooled to the final product.
The T. reesei wild-type cellobiohydrolase I and cellobiohydrolase I M6 variant were purified to a concentration of 57 μM and 38 μM, respectively, as determined by A 280 using the calculated molar extinction coefficient 84810 M −1 ·cm −1 and 84810 M −1 ·cm −1 , respectively.
Example 8: Activity Measurement on Microcrystalline Cellulose of the Trichoderma Reesei Cellobiohydrolase M6 Variant
The activity of the purified cellobiohydrolase I M6 variant (Example 7) was compared to the purified T. reesei wild-type cellobiohydrolase I (Example 7) using microcrystalline cellulose (AVICEL® PH101; Sigma-Aldrich, St. Louis, Mo., USA) as a substrate. The microcrystalline cellulose was suspended at 60 g per liter of 2 mM CaCl 2 -50 mM sodium acetate pH 5 as assay buffer.
Activity of the T. reesei wild-type cellobiohydrolase I and cellobiohydrolase I M6 variant was measured in a water-jacketed glass cell connected to a Julabo F12 water bath (Buch & Holm A/S, Herlev, Denmark). Each reaction chamber was filled with 5 ml of the microcrystalline cellulose suspension and magnetically stirred at 600 rpm. The enzyme was injected into the cell using 250 μl glass syringes (Hamilton Co., Boston, Mass., USA) with a Fusion 100 syringe pump (Chemyx Inc., Stafford, Tex., USA) to a final concentration of 100 nM (5 μg/ml) with an injection time of 1 second (wild-type: 8.8 μl, 528 μl/minute; M6 variant: 13.16 μl, 789 μl/minute). The reactions were allowed to proceed for 5 hours at 25° C. before being quenched with 80 μl of 1 M NaOH.
From each reaction 2 samples of 2 ml were removed and filtered with a 0.2 μM hydrophilic MINISART® NML syringe filter (Sartorius Stedim Biotech S.A., Goettingen, Germany). The filtrates were diluted 1:10 with milliQ water (control was measured undiluted) and the glucose, cellobiose, and cellotriose contents were analyzed using a Dionex ICS-5000 DC High-Performance Liquid Chromatography (HPLC) System (Thermo Scientific, Sunnyvale, Calif., USA) equipped with a 4 mm×25 cm CARBOPAC™ PA10 column (Thermo Scientific, Sunnyvale, Calif., USA), a Dionex GP40 gradient pump (Thermo Scientific, Sunnyvale, Calif., USA), and a Dionex ED40 electrochemical detector (Thermo Scientific, Sunnyvale, Calif., USA) with a gold working electrode (standard carbohydrate settings). Oligosaccharides were separated on the CARBOPAC™ PA10 column using the following gradient program at a flow rate of 1 ml per minute: 0-4 minutes isocratic elution with 50 mM sodium hydroxide; 4-28 minutes linear gradient to 100 mM sodium acetate in 90 mM sodium hydroxide; 28-29 minutes linear gradient to 450 mM sodium acetate in 200 mM sodium hydroxide; 29-30 minutes linear gradient to 100 mM sodium hydroxide; 30-31 minutes linear gradient to 50 mM sodium hydroxide; and 31-35 minutes reequilibration under the initial conditions. Combined external standards were ([glucose]/[cellobiose]/[cellotriose]): 1 μM/2 μM/0.5 μM, 2 μM/4 μM/1 μM, 3 μM/6 μM/1.5 μM, 4 μM/8 μM/2 μM, and 5 μM/10 μM/2.5 μM. Chromatogram peak integration, standard curve, and concentration determination were performed using a CHROMELEON® 7 Chromatography Data System (Thermo Fisher Scientific, Roskilde, Denmark).
The results as shown in FIG. 1 and Table 1 demonstrated that the cellobiohydrolase I M6 variant had an approximately 65% increase in activity toward microcrystalline cellulose compared to the wild-type cellobiohydrolase.
TABLE 1
Saccharide production from microcrystalline cellulose by the
T. reesei wild-type cellobiohydrolase I and the cellobiohydrolase
I M6 variant thereof after 5 hours at pH 5 and 25° C.
[glucose] (μM)
[cellobiose] (μM)
[cellotriose] (μM)
Control
15.9
1.6
2.5
Wild-type
22.9 ± 0.3
121.4 ± 4.3
5.4 ± 4 × 10 −3
M6 Variant
29.1 ± 10 −3
201.7 ± 0.5
8.1 ± 0.04
Example 9: Pretreated Corn Stover Hydrolysis Assay
Corn stover was pretreated at the U.S. Department of Energy National Renewable Energy Laboratory (NREL) using 1.4 wt % sulfuric acid at 165° C. and 107 psi for 8 minutes. The water-insoluble solids in the pretreated corn stover (PCS) contained 56.5% cellulose, 4.6% hemicellulose, and 28.4% lignin. Cellulose and hemicellulose were determined by a two-stage sulfuric acid hydrolysis with subsequent analysis of sugars by high performance liquid chromatography using NREL Standard Analytical Procedure #002. Lignin was determined gravimetrically after hydrolyzing the cellulose and hemicellulose fractions with sulfuric acid using NREL Standard Analytical Procedure #003.
Unmilled, unwashed PCS (whole slurry PCS) was prepared by adjusting the pH of the PCS to 5.0 by addition of 10 M NaOH with extensive mixing, and then autoclaving for 20 minutes at 120° C. The dry weight of the whole slurry PCS was 29%. Milled unwashed PCS (dry weight 32.35%) was prepared by milling whole slurry PCS in a Cosmos ICMG 40 wet multi-utility grinder (EssEmm Corporation, Tamil Nadu, India).
The hydrolysis of PCS was conducted using 2.2 ml deep-well plates (Axygen, Union City, Calif., USA) in a total reaction volume of 1.0 ml. The hydrolysis was performed with 50 mg of insoluble PCS solids per ml of 50 mM sodium acetate pH 5.0 buffer containing 1 mM manganese sulfate and various protein loadings of various enzyme compositions (expressed as mg protein per gram of cellulose). Enzyme compositions were prepared and then added simultaneously to all wells in a volume ranging from 50 μl to 200 μl, for a final volume of 1 ml in each reaction. The plate was then sealed using an ALPS-300™ plate heat sealer (Abgene, Epsom, United Kingdom), mixed thoroughly, and incubated at a specific temperature for 72 hours. All experiments reported were performed in triplicate.
Following hydrolysis, samples were filtered using a 0.45 μm MULTISCREEN® 96-well filter plate (Millipore, Bedford, Mass., USA) and filtrates analyzed for sugar content as described below. When not used immediately, filtered aliquots were frozen at −20° C. The sugar concentrations of samples diluted in 0.005 M H 2 SO 4 were measured using a 4.6×250 mm AMINEX® HPX-87H column (Bio-Rad Laboratories, Inc., Hercules, Calif., USA) by elution with 0.05% w/w benzoic acid-0.005 M H 2 SO 4 at 65° C. at a flow rate of 0.6 ml per minute, and quantitation by integration of the glucose, cellobiose, and xylose signals from refractive index detection (CHEMSTATION®, AGILENT® 1100 HPLC, Agilent Technologies, Santa Clara, Calif., USA) calibrated by pure sugar samples. The resultant glucose and cellobiose equivalents were used to calculate the percentage of cellulose conversion for each reaction.
Glucose and cellobiose were measured individually. Measured sugar concentrations were adjusted for the appropriate dilution factor. The net concentrations of enzymatically-produced sugars from unwashed PCS were determined by adjusting the measured sugar concentrations for corresponding background sugar concentrations in unwashed PCS at zero time point. All HPLC data processing was performed using MICROSOFT EXCEL™ software (Microsoft, Richland, Wash., USA).
The degree of cellulose conversion to glucose was calculated using the following equation: % cellulose conversion=[glucose concentration+(1.053× cellobiose concentration)]/[(glucose concentration+(1.053× cellobiose concentration) in a limit digest]×100. In order to calculate % cellulose conversion, a 100% conversion point was set based on a cellulase control (100 mg of T. reesei cellulase per gram cellulose. Triplicate data points were averaged and standard deviation was calculated.
Example 10: Preparation of an Enzyme Composition without Cellobiohydrolase I
The Aspergillus fumigatus GH6A cellobiohydrolase II (SEQ ID NO: 32 [DNA sequence] and SEQ ID NO: 33 [deduced amino acid sequence]) was prepared recombinantly in Aspergillus oryzae as described in WO 2011/057140. The filtered broth of the A. fumigatus cellobiohydrolase II was buffer exchanged into 50 mM sodium acetate pH 5.0 using a 400 ml SEPHADEX™ G-25 column. The fractions were pooled.
The T. reesei GH5 endoglucanase II (SEQ ID NO: 34 [DNA sequence] and SEQ ID NO: 35 [deduced amino acid sequence]) was prepared recombinantly according to WO 2011/057140 using Aspergillus oryzae as a host. The filtered broth of the T. reesei endoglucanase II was desalted and buffer-exchanged into 20 mM Tris pH 8.0 using tangential flow (10K membrane, Pall Corporation).
The Penicillium sp. ( emersonii ) GH61A polypeptide (SEQ ID NO: 36 [DNA sequence] and SEQ ID NO: 37 [deduced amino acid sequence]) was prepared recombinantly according to WO 2011/041397 using T. reesei as a host. To purify P. emersonii GH61A polypeptide, a fermentation culture medium was desalted using a tangential flow concentrator (Pall Filtron, Northborough, Mass., USA) equipped with a 5 kDa polyethersulfone membrane (Pall Filtron, Northborough, Mass., USA) into 20 mM Tris-HCl pH 8.5. The buffer-exchanged sample was loaded onto a Q SEPHAROSE® Fast Flow column (GE Healthcare, Piscataway, N.J., USA) preequilibrated with 20 mM Tris-HCl, pH 8.0, eluted with 20 mM Tris-HCl pH 8.0 and 1 M NaCl. Selected fractions were pooled, made in 0.85 M ammonium sulfate, and loaded onto a Phenyl SEPHAROSE® Fast Flow column preequilibrated with 20 mM Tris-HCl, pH 7.5 and 0.85 M ammonium sulfate, eluted with 20 mM Tris-HCl, pH 7.5. The fractions were pooled and desalted using a tangential flow concentrator (Pall Filtron, Northborough, Mass., USA) equipped with a 5 kDa polyethersulfone membrane into 50 mM sodium acetate pH 5.0.
The Aspergillus fumigatus GH10 xylanase (xyn3) (SEQ ID NO: 38 [DNA sequence] and SEQ ID NO: 39 [deduced amino acid sequence]) was prepared recombinantly according to WO 2006/078256 using Aspergillus oryzae BECh2 (WO 2000/39322) as a host. The filtered broth of the A. fumigatus xylanase was desalted and buffer-exchanged into 50 mM sodium acetate pH 5.0 using a HIPREP® 26/10 Desalting Column (GE Healthcare, Piscataway, N.J., USA).
The Aspergillus fumigatus Cel3A beta-glucosidase 4M mutant (SEQ ID NO: 40 [DNA sequence] and SEQ ID NO: 41 [deduced amino acid sequence]) was recombinantly prepared according to WO 2012/044915. The filtered broth of Aspergillus fumigatus Cel3A beta-glucosidase 4M was concentrated and buffer exchanged using a tangential flow concentrator (Pall Filtron, Northborough, Mass., USA) equipped with a 10 kDa polyethersulfone membrane (Pall Filtron, Northborough, Mass., USA) with 50 mM sodium acetate pH 5.0 containing 100 mM sodium chloride.
The Talaromyces emersonii CBS 393.64 beta-xylosidase (SEQ ID NO: 42 [DNA sequence] and SEQ ID NO: 43 [deduced amino acid sequence]) was prepared recombinantly according to Rasmussen et al., 2006 , Biotechnology and Bioengineering 94: 869-876 using Aspergillus oryzae JaL355 as a host (WO 2003/070956). The filtered broth was concentrated and desalted with 50 mM sodium acetate pH 5.0 using a tangential flow concentrator equipped with a 10 kDa polyethersulfone membrane.
The protein concentration for each of the monocomponents described above was determined using a Microplate BCA™ Protein Assay Kit (Thermo Fischer Scientific, Waltham, Mass., USA) in which bovine serum albumin was used as a protein standard. An enzyme composition was prepared composed of each monocomponent as follows: 39.7% Aspergillus fumigatus Cel6A cellobiohydrolase II, 15.9% T. reesei GH5 endoglucanase II, 23.8% Penicillium sp. ( emersonii ) GH61A polypeptide, 7.9% Aspergillus fumigatus GH10 xylanase, 7.9% Aspergillus fumigatus beta-glucosidase, and 4.8% Talaromyces emersonii beta-xylosidase. The enzyme composition is designated herein as “cellulolytic enzyme composition without cellobiohydrolase I”.
Example 11: Comparison of the Effect of the Trichoderma reesei Cellobiohydrolase I M6 Variant and Trichoderma reesei Wild-Type Cellobiohydrolase I in the Hydrolysis of Milled Unwashed PCS by a Cellulase Enzyme Composition
The T. reesei cellobiohydrolase I M6 variant and T. reesei wild-type cellobiohydrolase I were added to the cellulolytic enzyme composition without cellobiohydrolase I (Example 10) at 40° C. using milled unwashed PCS as a substrate. Each cellobiohydrolase I was added individually at 0.8633, 1.295, and 1.9425 mg enzyme protein per g cellulose to 2.205 mg enzyme protein of the cellulase enzyme composition without cellobiohydrolase I per g cellulose.
The assay was performed as described in Example 9. The 1 ml reactions with milled unwashed PCS (5% insoluble solids) were conducted for 24, 48, and 72 hours in 50 mM sodium acetate pH 5.0 buffer containing 1 mM manganese sulfate. All reactions were performed in triplicate and involved single mixing at the beginning of hydrolysis.
The results shown in FIGS. 2, 3, and 4 demonstrated that at 24, 48, and 72 hours, the cellulase enzyme composition that included the T. reesei cellobiohydrolase I M6 variant had significantly higher cellulose conversion than the cellulase enzyme composition that included T. reesei wild-type cellobiohydrolase I.
Example 12: Determination of Td by Differential Scanning Calorimetry of the Trichoderma reesei Cellobiohydrolase I M6 Variant and Trichoderma reesei Wild-Type Cellobiohydrolase I
The thermostability of the T. reesei wild-type cellobiohydrolase I and cellobiohydrolase I M6 variant was determined by Differential Scanning calorimetry (DSC) using a VP-Capillary Differential Scanning calorimeter (MicroCal Inc., Piscataway, N.J., USA). The thermal denaturation temperature, Td (° C.), was taken as the top of denaturation peak (major endothermic peak) in thermograms (Cp vs. T) obtained after heating enzyme solutions (approx. 1 mg/ml) in 50 mM sodium acetate pH 5.0 at a constant programmed heating rate of 200 K/hour.
Sample- and reference-solutions (approx. 0.2 ml) were loaded into the calorimeter (reference: buffer without enzyme) from storage conditions at 10° C. and thermally pre-equilibrated for 20 minutes at 20° C. prior to DSC scan from 20° C. to 100° C. Denaturation temperatures were determined at an accuracy of approximately +/−1° C.
The results demonstrated that the T. reesei wild-type cellobiohydrolase I has a Td of 69° C. compared to 68° C. for the cellobiohydrolase I M6 variant thereof.
Example 13: Site-Directed Mutagenesis of the Wild-Type Trichoderma reesei Cellobiohydrolase I
The codon-optimized synthetic gene encoding the wild-type T. reesei cellobiohydrolase I (Example 1) was used to generate the T. reesei cellobiohydrolase I TC1-111 variant (SEQ ID NO: 44 for the mutant DNA sequence and SEQ ID NO: 45 for the variant), an AAC codon (N198) was replaced with a GCA codon (198A).
To generate the T. reesei cellobiohydrolase I TC1-116 variant (SEQ ID NO: 46 for the mutant DNA sequence and SEQ ID NO: 47 for the variant), a GCC codon (A199) was deleted (A199*).
To generate the T. reesei cellobiohydrolase I TC1-61 variant (SEQ ID NO: 48 for the mutant DNA sequence and SEQ ID NO: 49 for the variant), an AAC codon (N200) was replaced with a TGG codon (200W).
To generate the T. reesei cellobiohydrolase I TC1-103 variant (SEQ ID NO: 50 for the mutant DNA sequence and SEQ ID NO: 51 for the variant), an AAC codon (N200) was replaced with a GGA codon (200G).
Two synthetic primers for each site-directed mutagenesis were designed as shown below using an SOE primer design tool. The introduced site-directed mutation changed an AAC codon (N198) to a GCA codon (198A), an AAC codon (N200) to a TGG codon (200W), and an AAC codon (N200) to a GGA codon (200G), and a GCC codon (A199) was deleted.
Primer F-N198A:
(SEQ ID NO: 52)
5′-GCTGGGAACCCTCGTCGAACGCAGCCAACACCGGCATTGGA-3′
Primer R-N198A:
(SEQ ID NO: 53)
5′-GTTCGACGAGGGTTCCCAGCCTTCGACGTTTG-3′
Primer F-ΔA199:
(SEQ ID NO: 54)
5′-TGGGAACCCTCGTCGAACAACAACACCGGCATTGGAGGCCAT-3′
Primer R-ΔA199:
(SEQ ID NO: 55)
5′-GTTGTTCGACGAGGGTTCCCAGCCTTCGACG-3′
Primer F-N200W:
(SEQ ID NO: 56)
5′-GAACCCTCGTCGAACAACGCCTGGACCGGCATTGGAGGCCATGG-3′
Primer R-N200W:
(SEQ ID NO: 57)
5′-GGCGTTGTTCGACGAGGGTTCCCAGCCTTCG-3′
Primer F-N200G:
(SEQ ID NO: 58)
5′-GAACCCTCGTCGAACAACGCCGGAACCGGCATTGGAGGCCAT-3′
Primer R-N200G:
(SEQ ID NO: 59)
5′-GGCGTTGTTCGACGAGGGTTCCCAGCCTTCG-3′
Site-directed mutagenesis of the synthetic gene encoding the wild-type T. reesei cellobiohydrolase was facilitated by PCR amplifications of the pDau109 vector containing the T. reesei cellobiohydrolase I gene: The T. reesei cellobiohydrolase I gene was previously cloned into Bam HI-Hind III digested pDau109 resulting in transcription of the T. reesei cellobiohydrolase I gene under the control of a NA2-tpi double promoter.
The mutations were introduced by PCR using a PHUSION® High-Fidelity PCR Kit. The PCR solution was composed of 10 μl of 5× HF buffer, 1 μl of dNTPs (10 mM), 0.5 μl of PHUSION® DNA polymerase (0.2 units/μl), 2.5 μl of primer F-N198A (10 μM), 2.5 μl of primer R-N198A (10 μM), 10 μl of template DNA (pDAu222- T. reesei cellobiohydrolase I, 1 ng/μl), and 23.5 μl of deionized water in a total volume of 50 μl. For the GCC deletion (A199* variant) 2.5 μl of primer F-ΔA199 (10 μM), 2.5 μl of primer R-ΔA199 (10 μM) were used. For the ACC to TGG mutation (N200W variant) 2.5 μl primer-F-N200W (10 μM) and 2.5 μl primer R-N200W (10 μM) were used. For the ACC to GGA mutation (N200G variant) 2.5 μl primer-F-N200G (10 μM) and 2.5 μl primer R-N200G (10 μM) were used.
The PCR was performed using a GeneAmp® PCR System 9700 (Applied Biosystems, Foster City, Calif., USA) programmed for 1 cycle at 98° C. for 30 seconds; and 19 cycles each at 98° C. for 30 seconds, 55° C. for 1 minute, and 72° C. for 4 minutes. The PCR solution was then held at 15° C. until removed from the PCR machine.
Following PCR, 10 units of Dpn I were added directly to the PCR solution and incubated at 37° C. for 1 hour. Then 1 μl of the Dpn I treated PCR solution was transformed into ONE SHOT® TOP10F′ Chemically Competent E. coli cells according to the manufacturer's protocol and spread onto LB plates supplemented with 0.15 mg of ampicillin per ml. After incubation at 37° C. overnight, transformants were observed growing under selection on the LB ampicillin plates. Two transformants were cultivated in LB medium supplemented with 0.15 mg of ampicillin per ml and plasmids were isolated using a QIAPREP® Spin Miniprep Kit.
The isolated plasmids were sequenced using an Applied Biosystems 3730xl DNA Analyzer with vector primers and T. reesei cellobiohydrolase 1 gene specific primers, shown below, in order to determine a representative plasmid that was free of PCR errors and contained the desired mutations.
Primer F-pDau109
(SEQ ID NO: 30)
5′-CCCTTGTCGATGCGATGTATC-3′
Primer F-Central1
(SEQ ID NO: 60)
5′-CATGTATCGTAAGCTCGCAGTCATCTCC-3′
Primer F-Central2
(SEQ ID NO: 61)
5′-CTTCGTGTCGATGGACGCGG-3′
Primer R-Central3
(SEQ ID NO: 62)
5′-GAACACGAGCCCCTCACTGC-3′
Primer R-pDau109
(SEQ ID NO: 31)
5′-ATCCTCAATTCCGTCGGTCGA-3′
One plasmid clone free of PCR errors and containing the AAC (N198) to GCA (198A) mutation was chosen and designated plasmid pN198A.
One plasmid clone free of PCR errors and containing the deletion of the GCC codon (A199) to (A199*) mutation was chosen and designated plasmid pΔA199.
One plasmid clone free of PCR errors and containing the AAC (N200) to TGG (200W) mutation was chosen and designated plasmid pN200W.
One plasmid clone free of PCR errors and containing the AAC (N200) to GGA (200G) mutation was chosen and designated plasmid pN200G.
pN198A was sequenced using primers F-Central1, F-Central2, R-Central3 and R-pDau109. pΔA199 was sequenced using primers F-pDau109 F-Central1, F-Central2, R-Central3 and R-pDau109. pN200W was sequenced using primers F-Central1, F-Central2 and R-pDau109. pN200G was sequenced using primers F-Central1, F-Central2 and R-pDau109
Example 14: Expression of the Trichoderma reesei Cellobiohydrolase I TC1-111, TC1-116, TC1-61, and TC1-103 Variants
Expression of plasmids pN198A, pΔA199, pN200W, and pN200G in Aspergillus oryzae MT3568 was performed according to the protocol described in Example 6.
Expression was verified by SDS-PAGE analysis using an E-Page 8% SDS-PAGE 48 well gel and Coomassie staining. Based on the level of expression by SDS-PAGE, one transformant was selected for each of plasmids pN198A, pΔA199, pN200W, and pN200G and designated Aspergillus oryzae ΔA199, N200G, N197A, and N200W, respectively.
For larger scale production, spores for each A. oryzae strain were spread onto COVE sucrose slants and incubated for five days at 37° C. Each confluent spore slant was washed twice with 5 ml of 0.01% TWEEN® 20 to maximize the number of spores collected. Each spore suspensions were then used to inoculate seven 500 ml flasks containing 150 ml of DAP-4C medium. The cultures were incubated at 30° C. with constant shaking at 100 rpm. At day four post-inoculation, the culture broths were collected by filtration through a bottle top MF75 Supor MachV 0.2 μm PES filter. Expression was verified by SDS-PAGE analysis using an E-Page 8% SDS-PAGE 48 well gel and Coomassie staining. The culture broths from each A. oryzae strain produced a band at approximately 80 kDa for the T. reesei A199*, N200G, N197A, and N200W cellobiohydrolase variant.
Example 15: Purification of the Trichoderma reesei Cellobiohydrolase I TC1-111, TC1-116, TC1-61, and TC1-103 Variants
The fermentation broths were filtered through PES Bottle top filter with a 0.22 μm cut-off (Thermo Fisher Scientific, Roskilde, Denmark). Ammonium sulphate was added to the filtered fermentation broths to make a 1.8 M solution.
The fermentation broths were purified by HIC/affinity chromatography followed by IEX/affinity chromatography.
In the HIC/affinity chromatographic step, the fermentation broths were applied to a 200 ml Phenyl SEPHAROSE® 6 Fast Flow column (high sub) equilibrated with 1.8 M ammonium sulphate, 25 mM HEPES pH 7.0. After applying the sample, the column was washed with 2 column volumes of 1.8 M ammonium sulphate followed by 1 column volume of 0.54 M ammonium sulphate. The bound proteins were batch eluted with 25 mM HEPES pH 7.0.
The elution of the protein was monitored at 280 nm. Fractions with high 280 nm absorbance were analyzed by SDS-PAGE using 12-well NUPAGE® 4-12% Bis-Tris gel for their cellobiohydrolase content. Fractions with high content of this protein were pooled and collected for further purification. The pooled fractions were desalted on a SEPHADEX™ G-25 (medium) column equilibrated with 25 mM MES pH 6.0. The elution of the protein was monitored at 280 nm and fractions with high absorbance at 280 nm were chosen for the second chromatographic step.
The pooled fractions were applied to the 60 ml RESOURCE™ 15Q column (equilibrated with 25 mM MES pH 6.0 and bound proteins were eluted with a linear 50-300 mM sodium chloride gradient for 3 column volumes. The elution of the protein was monitored at 280 nm and fractions with high absorbance at 280 nm were analysed on SDS-PAGE.
Fractions with high content of cellobiohydrolase I were pooled.
Example 16: Activity Measurement on Microcrystalline Cellulose of the Trichoderma Reesei Cellobiohydrolase I TC1-111, TC1-116, TC1-61, and TC1-103 Variants
The activity of the purified Trichoderma reesei cellobiohydrolase I TC1-111, TC1-116, TC1-61, and TC1-103 (variants were compared to the purified T. reesei wild-type cellobiohydrolase I using washed microcrystalline cellulose (AVICEL® PH101; Sigma-Aldrich, St. Louis, Mo., USA) as a substrate.
The washed microcrystalline cellulose was prepared by applying and mixing (by hand) 180 g of microcrystalline cellulose and approximately 400 ml of 0.22 μm filtered water to a centrifuge bottle (1 L). The centrifuge bottle was centrifuged at 4000 rpm for 5 minutes at 18° C. (Sorvall Hereaus Thermoscientific Sorvall Evolution RC superspeed centrifuge). The supernatant was removed and 400 ml of MQ water were added again. This was repeated 4 times. At the 4 th repeat the pellet and 0.22 μm filtered water were mixed on a “Rocker” o/n (IKA KS 130 basic) before centrifuging. The supernatant was removed and pellet was re-suspended with 50 mM sodium acetate, 2 mM CaCl 2 pH 5 buffer to a final concentration of 90 g/L.
The purified cellobiohydrolase variants were diluted in 50 mM sodium acetate, 2 mM CaCl 2 pH 5 to a concentration of 9 μM. Then 100 μl of the diluted cellobiohydrolase I variants were added to each well of a microtiter plate followed by 200 μl of washed microcrystalline cellulose at 90 g/liter to each well. The microtiter plate was quickly transferred to a thermomixer and incubated for 1 hour at 1100 rpm and 25° C. The reaction was stopped by centrifugation at 3500 rpm for 3 minutes at 5° C. using a HERAEUS® MULTIFUGE® 3 s-r centrifuge (Thermo Fisher Scientific, Roskilde, Denmark). Fifty μl of supernatant were transferred to PCR sample tubes (0.2 ml non-skirtet 96-well PCR plate; Thermo Fisher Scientific, Roskilde, Denmark). PAHBAH (4-hydroxy-benzhydrazide) was dissolved in buffer (0.18 M K—Na-tartrate and 0.5 M NaOH) to make a 15 mg/ml solution. Seventy-five μl of the PAHBAH solution were added to the supernatants in the PCR samples tubes.
The PCR sample tubes were placed in a Peltier Thermal Cycler and incubated at 95° C. for 10 minutes and 20° C. for 5 minutes. After incubation 100 μl were transferred to a 96 well microtiter plate and the absorbance was measured at 410 nm. For each run a standard was included. The standard used was cellobiose diluted in 50 mM sodium acetate, 2 mM CaCl 2 pH 5 to a concentration of 0.008, 0.016, 0.0312, 0.0625, 0.125, 0.25, 0.5, and 1 mM. In addition to the standard, a blank (without cellobiohydrolase) for each run was included. For all the measurements, the blank measurement was subtracted. The absorbance data were normalized to cellobiose concentration using the standards.
The results as shown in FIG. 5 demonstrated that the cellobiohydrolase A199* variant had an approximately 56% increase in activity toward microcrystalline cellulose compared to the wild-type cellobiohydrolase I. N200G variant had 40%, N198A had 23% and N200W had 3% increase in activity compared with wild-type cellobiohydrolase I.
Example 17: Pretreated Corn Stover Hydrolysis Assay
Corn stover was pretreated at the U.S. Department of Energy National Renewable Energy Laboratory (NREL) as described in Example 9.
Unmilled, unwashed PCS (whole slurry PCS) was prepared by adjusting the pH of the PCS to 5.0 by addition of 10 M NaOH with extensive mixing, and then autoclaving for 20 minutes at 120° C. The dry weight of the whole slurry PCS was 29%.
A 96-well plate was generated by machining a teflon plate of depth ¼ inch with 96, cone-shaped wells, diameter ¼ inch at the upper surface and diameter ⅛ inch at the lower surface. The center of each well was at an equivalent position to the center of a corresponding well in a standard 96-well microtiter plate, approximately 23/64 inch on center. The resulting volume of each well was approximately 135 μl. This 96-well aluminum plate is hereinafter referred to as the “fill plate”. The pH-adjusted unmilled, unwashed PCS was used to fill the holes in the fill plate by applying a suitable volume of the PCS to the upper surface of the plate, then using a spatula to spread the material over the surface and into the holes. Holes were deemed sufficiently full when the PCS was extruded through the hole in the bottom surface, forming noodle-like tubes. A MULTISCREEN® Column Loader Scraper (Millipore, Billerica, Mass., USA) held perpendicular to the fill plate surface was used to scrape excess PCS from the top and bottom surfaces of the fill plate, leaving the surfaces of the PCS in each well flush with the surfaces of the fill plate. The fill plate was then placed on the top of a 2.2 ml deep well plate (Axygen, Union City, Calif., USA) with the top surface adjacent to the open end of the well plate (e.g., the top of the well plate), and the wells aligned with the PCS-filled holes in the fill plate. The fill plate was secured in this position, and the assembly centrifuged at 2500 rpm (1350× g) for 5 minutes in a Sorvall Legend RT+(Thermo Scientific, Waltham, Mass., USA). Following centrifugation, the PCS had been transferred to the deep well plate. A 3 mm glass bead (Fisher Scientific, Waltham, Mass., USA) was placed in each well for mixing.
The hydrolysis of PCS was conducted in a total reaction volume of 0.2 ml. The hydrolysis was performed with 50 mg of insoluble PCS solids containing 50 mM sodium acetate pH 5.0 buffer containing 1 mM manganese sulfate and various protein loadings of various enzyme compositions (expressed as mg protein per gram of cellulose). Enzyme compositions were prepared and then added simultaneously to all wells in a volume ranging from 20 μl to 50 μl, for a final volume of 0.2-0.50 ml in each reaction. The plate was then sealed using an ALPS-300™ plate heat sealer, mixed thoroughly, and incubated at a specific temperature for 72 hours. All experiments reported were performed in triplicate.
Following hydrolysis, samples were filtered using a 0.45 μm MULTISCREEN® 96-well filter plate and filtrates analyzed for sugar content as described in Example 9.
Glucose was measured. The measured glucose concentration was adjusted for the appropriate dilution factor. The net concentration of enzymatically-produced glucose from unwashed PCS was determined by adjusting the measured glucose concentration for corresponding background glucose concentration in the unmilled, unwashed PCS at zero time point. All HPLC data processing was performed using MICROSOFT EXCEL™ software.
The degree of glucose conversion to glucose was calculated using the following equation: % glucose conversion=(glucose concentration)/(glucose concentration in a limit digest)×100. In order to calculate % glucose conversion, a 100% conversion point was set based on a cellulase control (100 mg of T. reesei cellulase per gram cellulose. Triplicate data points were averaged and standard deviation was calculated.
Example 18: Preparation of an Enzyme Composition #2 without Cellobiohydrolase I
An Aspergillus fumigatus GH6A cellobiohydrolase II variant (GENESEQP:AZN71803) was prepared recombinantly in Aspergillus oryzae as described in WO 2011/123450. The filtered broth of the A. fumigatus cellobiohydrolase II was desalted and buffer-exchanged into 50 mM sodium acetate pH 5.0 containing 100 mM sodium chloride using a tangential flow (10K membrane, Pall Corporation).
The Thermoascus aurantiacus GH5 endoglucanase II (GENESEQP:AZI04862) was prepared recombinantly according to WO 2011/057140 using Aspergillus oryzae as a host. The filtered broth of the T. aurantiacus endoglucanase II was concentrated using tangential flow (5K membrane, Pall Corporation). The concentrated protein was desalted using a 400 ml SEPHADEX™ G-25 column into 20 mM Tris pH 8.0.
The Penicillium sp. ( emersonii ) GH61A polypeptide was prepared as disclosed in Example 10.
The Aspergillus fumigatus GH10 xylanase (xyn3) was prepared as disclosed in Example 10.
The Aspergillus fumigatus Cel3A beta-glucosidase 4M mutant was prepared as described in Example 10. The protein concentration was determined using a Microplate BCA™ Protein Assay Kit (Thermo Fischer Scientific, Waltham, Mass., USA) in which bovine serum albumin was used as a protein standard.
The Talaromyces emersonii CBS 393.64 beta-xylosidase was prepared as described in Example 10.
The protein concentration for each of the monocomponents described above was determined using a Microplate BCA™ Protein Assay Kit in which bovine serum albumin was used as a protein standard, except the Penicillium sp. ( emersonii ) GH61A polypeptide, which was determined at A 280 using the theoretical molar extinction coefficient 41730 M −1 ·cm −1 . An enzyme composition was prepared composed of each monocomponent as follows: 39.7% Aspergillus fumigatus Cel6A variant cellobiohydrolase II, 15.9% T. reesei GH5 endoglucanase II, 23.8% Penicillium sp. ( emersonii ) GH61A polypeptide, 7.9% Aspergillus fumigatus GH10 xylanase, 7.9% Aspergillus fumigatus beta-glucosidase, and 4.8% Talaromyces emersonii beta-xylosidase. The enzyme composition is designated herein as “cellulolytic enzyme composition #2 without cellobiohydrolase I”.
Example 19: Source of DNA Sequence Information for Rasamsonia emersonii Cellobiohydrolase I
The genomic DNA sequence and deduced amino acid sequence of the wild-type Rasamsonia emersonii GH7 cellobiohydrolase I gene is shown in SEQ ID NO: 11 and SEQ ID NO: 12, respectively. The gene sequence is 99% identical to Genbank entry AF439935.4. The cDNA sequence and deduced amino acid sequence of the Rasamsonia emersonii cellobiohydrolase I gene is shown in SEQ ID NO: 63 and SEQ ID NO: 12, respectively.
Based on the cDNA sequence for Rasamsonia emersonii cellobiohydrolase I, a codon-optimized synthetic gene encoding the full-length cellobiohydrolase I was generated for Aspergillus oryzae expression based on the algorithm developed by Gustafsson et al., 2004 , Trends in Biotechnology 22 (7): 346-353. The codon-optimized coding sequence (SEQ ID NO: 64) was synthesized by the GENEART® Gene Synthesis service (Life Technologies Corp., San Diego. Calif., USA) with a 5′ Bam HI restriction site, a 3′ Hind III restriction site, and a Kozac consensus sequence (CACC) situated between the start codon and the Bam HI restriction site.
Example 20: Site-Directed Mutagenesis of the Wild-Type Rasamsonia emersonii Cellobiohydrolase I
The codon-optimized synthetic gene encoding the wild-type Rasamsonia emersonii cellobiohydrolase I was provided in a non-specified kanamycin-resistant E. coli cloning vector.
To generate the R. emersonii cellobiohydrolase I PC1-146 variant (SEQ ID NO: 65 for the mutant DNA sequence and SEQ ID NO: 66 for the variant), an AAC codon (N194) was replaced with a GCA codon (194A) and an AAC codon (N197) was replaced with a GCA codon (197A).
Two synthetic primers for site-directed mutagenesis were designed as shown below using a SOE primer design tool. The introduced site-directed mutation changed an AAC codon (N194) to a GCA codon (194A) and an AAC codon (N197) to a GCA codon (197A).
Primer F-N194A N197A:
(SEQ ID NO: 67)
5′-AAGGATGGCAGCCCTCGTCCGCAAACGCGGCAACTGGCATCGGTGAT
CAC-3′
Primer R-N194A N197A:
(SEQ ID NO: 68)
5′-GGACGAGGGCTGCCATCCTTCCACGTTCGC-3′
Site-directed mutagenesis of the synthetic gene encoding the wild-type R. emersonii cellobiohydrolase I was facilitated by PCR amplification of the pDau109 vector containing the R. emersonii cellobiohydrolase 1 gene designated pDau222- R. emersonii cellobiohydrolase I. The R. emersonii cellobiohydrolase 1 gene was previously cloned into Bam HI-Hind III digested pDau109 resulting in transcription of the R. emersonii cellobiohydrolase 1 gene under the control of a NA2-tpi double promoter.
The mutations were introduced by PCR using a PHUSION® High-Fidelity PCR Kit. The PCR solution was composed of 10 μl of 5× HF buffer, 1 μl of dNTPs (10 mM), 0.5 μl of PHUSION® DNA polymerase (0.2 units/μl), 0.25 μl of primer F-N194A N197A (100 μM), 0.25 μl of primer R-N194A N197A (100 μM), 10 μl of template DNA (pDau222- R. emersonii cellobiohydrolase I, 1 ng/μl), and 28 μl of deionized water in a total volume of 50 μl. The PCR was performed using a GeneAmp® PCR System 9700 (Applied Biosystems, Foster City, Calif., USA) programmed for 1 cycle at 98° C. for 30 seconds; and 19 cycles each at 98° C. for 30 seconds, 55° C. for 1 minute, and 72° C. for 4 minutes. The PCR solution was then held at 8° C. until removed from the PCR machine.
Following PCR, 10 units of Dpn I were added directly to the PCR solution and incubated at 37° C. for 1 hour. Then 1 μl of the Dpn I treated PCR solution was transformed into ONE SHOT® TOP10F′ Chemically Competent E. coli cells according to the manufacturer's protocol and spread onto LB plates supplemented with 0.15 mg of ampicillin per ml. After incubation at 37° C. overnight, transformants were observed growing under selection on the LB ampicillin plates. Four transformants were cultivated in LB medium supplemented with 0.15 mg of ampicillin per ml and plasmids were isolated using a QIAPREP® Spin Miniprep Kit.
The isolated plasmids were sequenced using an Applied Biosystems 3730xl DNA Analyzer with vector primers and R. emersonii cellobiohydrolase 1 gene specific primers, shown below, in order to determine a representative plasmid that was free of PCR errors and contained the desired mutations.
Primer F-pDau109
(SEQ ID NO: 69)
5′-CCACACTTCTCTTCCTTCCTCAATCCTC-3′
Primer F-Central1
(SEQ ID NO: 70)
5′-GTGAGGCGAACGTGGAAGGATG-3′
Primer R-Central2
(SEQ ID NO: 71)
5′-gtacctgtgtccgtgccgtcatctg-3′
Primer R-pDau109
(SEQ ID NO: 31)
5′-ATCCTCAATTCCGTCGGTCGA-3′
One plasmid clone free of PCR errors and containing the AAC (N194) to GCA (194A) mutation and the AAC (N197) to GCA (197A) mutation was chosen and designated plasmid pE146. The variant is designated herein as PC1-146.
Example 21: Construction of an Aspergillus oryzae Expression Vector Containing a Rasamsonia emersonii DNA Sequence Encoding Cellobiohydrolase I
The kanamycin-resistant E. coli cloning vector provided by GENEART® Gene Synthesis encoding the Rasamsonia emersonii cellobiohydrolase I was digested with Fast Digest Bam HI and Hind III (Fermentas Inc., Glen Burnie, Md., USA) according to manufacturer's instructions. The reaction products were isolated by 1.0% agarose gel electrophoresis using TAE buffer where a 1375 bp product band was excised from the gel and purified using an ILLUSTRA™ GFX™ DNA Purification Kit.
The 1375 bp fragment was then cloned into pDau109 digested with Bam HI and Hind III using T4 DNA ligase. The Bam HI-Hind III digested pDau109 and the Bam HI/Hind III fragment containing the T. reesei cellobiohydrolase I coding sequence were mixed in a molar ratio of 1:3 (i.e., mass ratio approximately 2.5:1 or 20 ng:50 ng) and ligated with 50 units of T4 DNA ligase in 1× T4 DNA ligase buffer with 1 mM ATP at 16° C. over-night in accordance with the manufacturer's instructions. Cloning of the Rasamsonia emersonii cellobiohydrolase I gene into Bam HI-Hind III digested pDau109 resulted in the transcription of the Rasamsonia emersonii cellobiohydrolase I gene under the control of a NA2-tpi double promoter.
The ligation mixture was transformed into ONE SHOT® TOP10F′ Chemically Competent E. coli cells according to the manufacturer's protocol and spread onto LB plates supplemented with 0.1 mg of ampicillin per ml. After incubation at 37° C. overnight, transformants were observed growing under selection on the LB ampicillin plates. Insertion of the Rasamsonia emersonii cellobiohydrolase I gene into pDau109 was verified by PCR on the transformants as described below using primers F-pDau109 and R-pDau109.
A 1.1× REDDYMIX® Master Mix (Thermo Fisher Scientific, Roskilde, Denmark) was used for the PCR. The PCR solution was composed of 10 μl of 1.1× REDDYMIX® Master Mix, 0.5 μl of primer F-pDau109 (10 μM), and 0.5 μl of primer R-pDau109 (10 μM). A toothpick was used to transfer a small amount of cells to the PCR solution. The PCR was performed using a PTC-200 DNA Engine programmed for 1 cycle at 94° C. for 3 minutes; 30 cycles each at 94° C. for 30 seconds, 50° C. for 1 minute, and 72° C. for 2 minutes; and 1 cycle at 72° C. for 1 minute. The PCR solution was then held at 15° C. until removed from the PCR machine.
The PCR products were analyzed by 1.0% agarose gel electrophoresis using TAE buffer where a 1600 bp PCR product band was observed confirming insertion of the Rasamsonia emersonii cellobiohydrolase I coding sequence into pDau109.
An E. coli transformant containing the Rasamsonia emersonii cellobiohydrolase I plasmid construct was cultivated in LB medium supplemented with 0.1 mg of ampicillin per ml and plasmid DNA was isolated using a QIAPREP® Spin Miniprep Kit. The plasmid was designated pKHJN0135.
Example 22: Expression of the Wild-Type Rasamsonia emersonii Cellobiohydrolase I
The expression plasmid pKHJN0135 was transformed into Aspergillus oryzae MT 3568 protoplasts according to Christensen et al., 1988, supra and WO 2004/032648. A. oryzae MT3568 protoplasts were prepared according to the method of EP 0238023 B1, pages 14-15.
Transformants were purified on COVE sucrose plates through single conidia prior to sporulating them on PDA plates. Spores of the transformants were inoculated into 96 deep well plates containing 0.75 ml of YP+2% glucose medium and incubated stationary at 30° C. for 4 days. Production of the Rasamsonia emersonii cellobiohydrolase I by the transformants was analyzed from culture supernatants of the 96 deep well cultivations. Expression was verified by SDS-PAGE analysis using an E-Page 8% SDS-PAGE 48 well gel and Coomassie blue staining. Based on the level of expression by SDS-PAGE, one transformant was selected for further work and designated Aspergillus oryzae ReCBH I.
For larger scale production, A. oryzae ReCBH I spores were spread onto COVE sucrose slants and incubated for five days at 37° C. The confluent spore slants were washed twice with 5 ml of 0.01% TWEEN® 20 to maximize the number of spores collected. The spore suspensions were then used to inoculate seven 500 ml flasks containing 150 ml of DAP-4C medium. The cultures were incubated at 30° C. with constant shaking at 100 rpm. At day four post-inoculation, the culture broths were collected by filtration through a bottle top MF75 Supor MachV 0.2 μm PES filter. Expression was verified by SDS-PAGE analysis using an E-Page 8% SDS-PAGE 48 well gel and Coomassie staining. The culture broths from A. oryzae ReCBH I produced a band at approximately 60 kDa for the Rasamsonia emersonii cellobiohydrolase I.
For larger scale production, A. oryzae ReCBH I spores were spread onto COVE sucrose slants and incubated for five days at 37° C. The confluent spore slants were washed twice with 5 ml G2-Gly medium. The spore suspensions were then used to inoculate 500 ml flasks containing 150 ml of G2-Gly medium. These pre-cultures were incubated at 30° C. with constant shaking at 150 rpm. After one day, each of the pre-cultures was used to inoculate four 500 ml flasks containing 150 ml DAP4C-1 medium. At day four post-inoculation, the culture broths were collected by filtration through a bottle top MF75 Supor MachV 0.2 μm PES filter.
Example 23: Expression of the Rasamsonia emersonii Cellobiohydrolase I PC1-146 Variant
The expression plasmid pE146 was transformed into Aspergillus oryzae MT3568 protoplasts according to Christensen et al., 1988, supra and WO 2004/032648. A. oryzae MT3568 protoplasts were prepared according to the method of EP 0238023 B1, pages 14-15.
Transformants were purified on COVE sucrose plates without CsCl through single conidia. Spores of the transformants were inoculated into 96 deep well plates containing 0.50 ml of YP+2% maltose medium and incubated stationary at 34° C. for 6 days. Production of the R. emersonii cellobiohydrolase I PC1-146 variant by the transformants was analyzed from culture supernatants of the 96 deep well cultivations. Expression was verified by measuring released reducing sugars from hydrolysis of microcrystalline cellulose. The hydrolysis was performed in 96 well microtiter plates (NUNC Thermo Fisher Scientific, Roskilde, Denmark) at 25° C. and 1100 rpm. Each hydrolysis reaction mixture contained 167 μl of microcrystalline cellulose at 90 g/liter in 50 mM sodium acetate pH 5.0, 0.01% TRITON® X-100, 20 μl of culture supernatant, and 63 μl of 50 mM sodium acetate pH 5.0, 0.01% TRITON® X-100. The plates were sealed with tape. The hydrolysis reaction was stopped by spinning the plate at 3500 rpm for 3 minutes. Then 50 μl of the reaction supernatant were added to 75 μl of stop solution in a 96 well PCR plate (Thermo Fisher Scientific, Roskilde, Denmark). The stop solution was composed of 15 mg/ml 4-hydroxybenzhydrazide (Sigma Chemical Co., Inc., St. Louis, Mo., USA), 50 mg/ml K—Na-tartrate (Sigma Chemical Co., Inc., St. Louis, Mo., USA) in 2% (w/v) NaOH. The plate was sealed with a lid and the mixture was incubated at 95° C. for 10 minutes and 5 minutes at 20° C. Then 100 μl was transferred to a microtiter plate and absorbance at 410 nm was measured using a SPECTRAMAX® Plus 384 (Molecular Devices, Sunnyvale, Calif., USA). The concentration of reducing sugar was proportional to the absorbance at 410 nm of the oxidized 4-hydroxybenzhydrazide. The reducing sugar content in the culture supernatants was measured by adding 4 μl of culture supernatant to a mixture of 75 μl of stop solution and 46 μl of milliQ water in a 96 well PCR plate. The plate was sealed with a lid and the mixture was incubated at 95° C. for 10 minutes and 5 minutes at 20° C. Then 100 μl was transferred to a microtiter plate and the absorbance at 410 nm was measured. The absorbance at 410 nm from the cell culture supernatant was subtracted from the absorbance at 410 nm of the hydrolysis reaction, to measure the amount of reducing sugar released by the enzymes.
Based on the level of hydrolysis of the microcrystalline cellulose one transformant was selected and designated A. oryzae PC1-146.
For larger scale production, A. oryzae PC1-146 spores were spread onto COVE sucrose slants and incubated for five days at 37° C. The confluent spore slants were washed twice with 5 ml of G2-Gly medium. The spore suspensions were then used to inoculate 500 ml flasks containing 150 ml of G2-Gly medium. These pre-cultures were incubated at 30° C. with constant shaking at 150 rpm. After one day, each of the pre-cultures was used to inoculate four 500 ml flasks containing 150 ml of DAP-4C medium. At day four post-inoculation, the culture broths were collected by filtration through a bottle top MF75 Supor MachV 0.2 μm PES filter.
Example 24: Purification of the Rasamsonia emersonii Wild-Type Cellobiohydrolase I and R. emersonii Cellobiohydrolase I PC1-146 Variant
The fermentation broths were filtered through a PES Bottle top filter with a 0.22 μm cut-off. Ammonium sulphate was added to the filtered fermentation broths to a concentration of 1.8 M. The fermentation broths were purified by HIC/affinity chromatography followed by IEX/affinity chromatography.
In the HIC/affinity chromatographic step, the fermentation broths were applied to a 200 ml Phenyl SEPHAROSE® 6 Fast Flow column (high sub) equilibrated with 1.8 M ammonium sulphate, 25 mM HEPES pH 7.0. After applying the sample, the column was washed with 2 column volumes of 1.8 M ammonium sulphate followed by 1 column volume of 0.54 M ammonium sulphate. The bound proteins were batch eluted with 25 mM HEPES pH 7.0.
The elution of the protein was monitored at 280 nm. Fractions with high 280 nm absorbance were analyzed by SDS-PAGE using 12-well NUPAGE® 4-12% Bis-Tris gel for their cellobiohydrolase content. Fractions with high content of the protein were pooled and collected for further purification. The pooled fractions were desalted on a SEPHADEX™ G-25 (medium) column equilibrated with 25 mM MES pH 6.0. The elution of the protein was monitored at 280 nm and fractions with high absorbance at 280 nm were chosen for the second chromatographic step.
The pooled fractions were applied to a 60 ml RESOURCE™ 15Q column equilibrated with 25 mM MES pH 6.0 and bound proteins were eluted with a linear 100-200 mM sodium chloride gradient for 1.5 column volumes followed by 1.5 column volumes of 300 mM sodium chloride, and followed by 1.5 column volumes of 1 M sodium chloride. The elution of the protein was monitored at 280 nm and fractions with high absorbance at 280 nm were analyzed on SDS-PAGE. Fractions with high content of cellobiohydrolase I were pooled.
Example 25: Activity Measurement on Microcrystalline Cellulose of the Rasamsonia Emersonii Cellobiohydrolase I PC1-146 Variant
The activity of the purified R. emersonii cellobiohydrolase I PC1-146 variant was compared to the purified T. reesei wild-type cellobiohydrolase I using washed microcrystalline cellulose (AVICEL® PH101; Sigma-Aldrich, St. Louis, Mo., USA) as a substrate.
The purified cellobiohydrolase variant was diluted in 50 mM sodium acetate, 2 mM CaCl 2 pH 5 to a concentration of 0.4 μM. Then 50 μl of the diluted cellobiohydrolase I variant were added to each well of a microtiter plate followed by 200 μl of washed microcrystalline cellulose at 90 g/liter to each well. The microtiter plate was quickly transferred to a thermomixer and incubated for 1 hour at 1100 rpm and 50° C. The reaction was stopped by centrifugation at 3500 rpm for 3 minutes at 5° C. using a HERAEUS® MULTIFUGE® 3 s-r centrifuge. Fifty μl of supernatant were transferred to PCR sample tubes (0.2 ml non-skirtet 96-well PCR plate). PAHBAH (4-hydroxy-benzhydrazide) was dissolved in buffer (0.18 M K—Na-tartrate and 0.5 M NaOH) to make a 15 mg/ml solution. Seventy-five μl of the PAHBAH solution were added to the supernatants in the PCR samples tubes.
The PCR sample tubes were placed in a Peltier Thermal Cycler and incubated at 95° C. for 10 minutes and 20° C. for 5 minutes. After incubation 100 μl were transferred to a 96 well microtiter plate and the absorbance was measured at 410 nm. For each run a standard was included. The standard used was cellobiose diluted in 50 mM sodium acetate, 2 mM CaCl 2 pH 5 to a concentration of 0.008, 0.016, 0.0312, 0.0625, 0.125, 0.25, 0.5, and 1 mM. In addition to the standard, a blank (without cellobiohydrolase) for each run was included. For all the measurements, the blank measurement was subtracted. The absorbance data were normalized to cellobiose concentration using the standards.
The results as shown in FIG. 6 demonstrated that the R. emersonii cellobiohydrolase I PC1-146 variant had an approximately 17% increase in activity toward microcrystalline cellulose compared to the R. emersonii wild-type cellobiohydrolase I.
Example 26: Determination of Td of the Rasamsonia emersonii Cellobiohydrolase I PC1-146 Variant by Differential Scanning Calorimetry
The thermostability of the R. emersonii cellobiohydrolase I PC1-146 variant was determined by Differential Scanning calorimetry (DSC) using a VP-Capillary Differential Scanning calorimeter as described in Example 12.
The results demonstrated that the R. emersonii wild-type cellobiohydrolase I has a Td of 78° C. compared to 78° C. for the R. emersonii cellobiohydrolase I PC1-146 variant thereof.
Example 27: Comparison of the Effect of Rasamsonia emersonii Cellobiohydrolase I PC1-146 Variant and Rasamsonia emersonii Wild-Type Cellobiohydrolase I on the Hydrolysis of Unwashed PCS by a Cellulase Enzyme Composition
The R. emersonii cellobiohydrolase I PC1-146 variant and R. emersonii wild-type cellobiohydrolase I were added to cellulolytic enzyme composition #2 without cellobiohydrolase I (Example 18) at 25° C. using unmilled, unwashed PCS as a substrate. For hydrolysis at 8% total solids, each cellobiohydrolase I was added individually at 2.22 mg enzyme protein per g cellulose to 3.78 mg enzyme protein of the cellulase enzyme composition #2 without cellobiohydrolase I per g cellulose. For hydrolysis as 20% total solids, each cellobiohydrolase I was added individually at 4.44 mg enzyme protein per g cellulose to 7.56 mg enzyme protein of the cellulase enzyme composition #2 without cellobiohydrolase I per g cellulose.
The assay was performed as described in Example 17. The reactions with unmilled, unwashed PCS (8% and 20% total solids) were conducted for 24, 48, and 72 hours in 50 mM sodium acetate pH 5.0 buffer containing 1 mM manganese sulfate. All reactions were performed in quadruplicate and shaking at 200 rpm throughout the hydrolysis.
The results shown in FIG. 7 (8% total solids) and FIG. 8 (20% total solids) demonstrated that at 24, 48, and 72 hours, the cellulase enzyme composition that included the R. emersonii cellobiohydrolase I PC1-146 variant had significantly higher cellulose conversion than the cellulase enzyme composition that included R. emersonii wild-type cellobiohydrolase I.
Example 28: Comparison of Rasamsonia emersonii Cellobiohydrolase I PC1-146 Variant with Rasamsonia emersonii Wild-Type Cellobiohydrolase I During Hydrolysis
Evaluation of the R. emersonii cellobiohydrolase I PC1-146 variant and the R. emersonii wild-type cellobiohydrolase I was performed on unmilled, unwashed PCS at 20% TS. The enzyme matrix design is shown below in Table 1. CELLIC® HTec3 was obtained from Novozymes A/S, Bagsvaerd, Denmark. Enzymatic hydrolysis was conducted at 32° C. for 3 and 5 days. The sugar released was analyzed by HPLC (1200 Series LC System, Agilent Technologies Inc., Palo Alto, Calif., USA) equipped with a Rezex ROA-Organic acid H + column (8%) (7.8×300 mm) (Phenomenex Inc., Torrance, Calif., USA), 0.2 mm in line filter, an automated sampler, a gradient pump and a refractive index detector. The mobile phase used was 5 mM sulfuric acid at a flow rate of 0.9 ml/min. Glucose at different concentrations was used as standards.
The results as shown in FIG. 9 demonstrated that the R. emersonii cellobiohydrolase I PC1-146 variant performed better than the wild-type R. emersonii cellobiohydrolase I.
TABLE 1
en-
zyme
dose
R.
R.
mg/g
emersonii
emersonii
Af
glu-
CBH I
CBH I
CBH
Ta
Aa
CELLIC ®
Tube
can
Variant
Wild-type
II
EG
BG
Htec3
1
6
37.5%
37.5%
10%
5%
10%
2
6
37.5%
37.5%
10%
5%
10%
Example 29: Comparison of Rasamsonia emersonii Cellobiohydrolase I PC1-146 Variant with Rasamsonia emersonii Wild-Type Cellobiohydrolase I During Simultaneous Saccharification and Fermentation (SSF)
The experimental design was the same as shown in Example 28, except that RED STAR® yeast at 1 g per liter and urea at 2 g per liter were added together with the enzyme during the beginning of the hydrolysis. Ethanol release was analyzed by HPLC using the system described in Example 28. Ethanol at different concentrations was used as standards.
The results as shown in FIG. 10 demonstrate that the R. emersonii cellobiohydrolase I PC1-146 variant performed better than the wild-type R. emersonii cellobiohydrolase I during SSF.
Example 30: Construction of a Rasamsonia emersonii Fusion Cellobiohydrolase I with Linker and Carbohydrate Binding Module from Trichoderma reesei Cellobiohydrolase I
The codon-optimized synthetic gene encoding the T. reesei ( H. jecorina ) cellobiohydrolase I is described in Example 1.
The codon-optimized synthetic gene encoding the R. emersonii cellobiohydrolase I is described in Example 19.
To generate a gene encoding a R. emersonii fusion cellobiohydrolase I with linker and carbohydrate binding module (CBM) from T. reesei cellobiohydrolase I (SEQ ID NO: 72 for the fusion protein DNA sequence and SEQ ID NO: 73 for the fusion protein), a DNA fragment encoding T. reesei cellobiohydrolase I linker and CBM was assembled to the 3′-end of the gene encoding the R. emersonii cellobiohydrolase I using splicing overlap extension (SOE) PCR.
The DNA fragment encoding the T. reesei cellobiohydrolase I linker and CBM was amplified using primer F-SOE and primer R-pDau109 shown below.
Primer F-SOE
(SEQ ID NO: 74)
5′-GGTCCCATCAACTCGACATTCACAGCCTCGGGTGGAAACCCTCCTGG
CGGAAACCCTC-3′
Primer R-pDau109
(SEQ ID NO: 31)
5′-ATCCTCAATTCCGTCGGTCGA-3′
Primer F-pDau109
(SEQ ID NO: 69)
5′-CCACACTTCTCTTCCTTCCTCAATCCTC-3′
The amplification of the DNA fragment encoding the T. reesei cellobiohydrolase 1 linker and CBM was performed using a PHUSION® High-Fidelity PCR Kit. The PCR solution was composed of 10 μl of 5× HF buffer, 1 μl of dNTPs (10 mM), 0.5 μl of PHUSION® DNA polymerase (0.2 units/μl), 0.25 μl of primer F-SOE (100 μM), 0.25 μl of primer R-pDau109 (100 μM), 10 μl of template DNA (pDAu222- T. reesei cellobiohydrolase I, 1 ng/μl), and 28 μl of deionized water in a total volume of 50 μl. The PCR was performed using a GeneAmp® PCR System 9700 programmed for 1 cycle at 98° C. for 30 seconds; and 30 cycles each at 98° C. for 10 seconds, 55° C. for 30 seconds, and 72° C. for 1 minute. The PCR solution was then held at 8° C. until removed from the PCR machine.
The PCR solution was submitted to 1% agarose gel electrophoresis using TAE buffer where a 405 bp PCR fragment encoding the T. reesei a linker and CBM was excised from the gel and purified using a MinElute Gel Extraction Kit (QIAGEN Inc., Valencia, Calif., USA).
A DNA fragment encoding the R. emersonii cellobiohydrolase I was amplified using primer F-pDau109 and primer R-pDau109 above.
The amplification of the DNA fragment encoding the R. emersonii wild-type cellobiohydrolase I was performed using a PHUSION® High-Fidelity PCR Kit. The PCR solution was composed of 10 μl of 5× HF buffer, 1 μl of dNTPs (10 mM), 0.5 μl of PHUSION® DNA polymerase (0.2 units/μl), 0.25 μl of primer F-pDAu109 (100 μM), 0.25 μl of primer R-pDau109 (100 μM), 10 μl of template DNA (pDAu222- R. emersonii cellobiohydrolase I, 1 ng/μl), and 28 μl of deionized water in a total volume of 50 μl. The PCR was performed using a GeneAmp® PCR System 9700 programmed for 1 cycle at 98° C. for 30 seconds; and 30 cycles each at 98° C. for 10 seconds, 55° C. for 30 seconds, and 72° C. for 1 minute. The PCR solution was then held at 8° C. until removed from the PCR machine.
The PCR solution was submitted to 1% agarose gel electrophoresis using TAE buffer where a 1600 bp fragment encoding the R. emersonii wild-type cellobiohydrolase I was excised from the gel and purified using a MinElute Gel Extraction Kit.
The two purified DNA fragments were assembled using SOE PCR and a PHUSION® High-Fidelity PCR Kit. The PCR solution was composed of 10 μl of 5× HF buffer, 1 μl of dNTPs (10 mM), 0.5 μl of PHUSION® DNA polymerase (0.2 units/μl), 0.25 μl of primer F-pDAu109 (100 μM), 10 μl of gel purified fragment encoding T. reesei cellobiohydrolase 1 linker and CBM, 2 μl of DNA fragment encoding R. emersonii cellobiohydrolase I, and 26 μl of deionized water in a total volume of 50 μl. The PCR was performed using a GeneAmp® PCR System 9700 programmed for 1 cycle at 98° C. for 30 seconds; and 30 cycles each at 98° C. for 20 seconds, 55° C. for 30 seconds, and 72° C. for 1 minute. The PCR solution was then held at 8° C. until removed from the PCR machine.
The PCR generated DNA fragment was then digested with Bam HI (New England Biolabs, Ipswich, Mass., USA) and Hind III (New England Biolabs, Ipswich, Mass., USA) as follows. Forty μl of PCR product were mixed with 5 μl buffer 2 (New England Biolabs, Ipswich, Mass., USA), 1 μl of Bam HI, and 1 μl of Hind III and incubated for 4 hours at 37° C. The resulting DNA product was submitted to 1% agarose gel electrophoresis using TAE buffer. A band of approximately 1567 bp was excised from the gel and purified using a MinElute Gel Extraction Kit.
The purified 1567 bp fragment encoding the R. emersonii cellobiohydrolase I with linker and carbohydrate binding module (CBM) from T. reesei cellobiohydrolase I was cloned into pDAu109 digested with Bam HI and Hind III using T4 DNA ligase. The Bam HI-Hind III digested pDau109 and the Bam HI/Hind III fragment containing the R. emersonii cellobiohydrolase I with linker and carbohydrate binding module (CBM) from T. reesei cellobiohydrolase I coding sequence were mixed in a molar ratio of 1:3 (i.e., equal volumes of gel purified products) and ligated with 50 units of T4 DNA ligase in 1× T4 DNA ligase buffer with 1 mM ATP and incubated at 22° C. for 10 minutes.
The ligation mixture was transformed into ONE SHOT® TOP10F′ Chemically Competent E. coli cells according to the manufacturer's protocol and spread onto LB plates supplemented with 0.1 mg of ampicillin per ml. After incubation at 37° C. overnight, transformants were observed growing under selection on the LB ampicillin plates. Two transformants were cultivated in LB medium supplemented with 0.15 mg of ampicillin per ml and plasmids were isolated using a QIAPREP® Spin Miniprep Kit.
The insertion of the DNA fragment encoding the R. emersonii cellobiohydrolase I with linker and carbohydrate binding module (CBM) from T. reesei cellobiohydrolase I into pDAu109 was verified by sequencing. The isolated plasmids were sequenced using an Applied Biosystems 3730xl DNA Analyzer with vector primers F-pDau109 and R-pDau109 in order to determine a representative plasmid that was free of PCR errors and contained the correct insertion.
One plasmid clone free of PCR errors and containing the DNA fragment encoding the R. emersonii cellobiohydrolase I with linker and carbohydrate binding module (CBM) from T. reesei cellobiohydrolase I was chosen and designated plasmid pE147. The fusion cellobiohydrolase I is designated herein as PC1-147.
Example 31: Site-Directed Mutagenesis of the Rasamsonia emersonii PC1-147 Fusion Cellobiohydrolase I
The fusion protein gene encoding the R. emersonii PC1-147 fusion cellobiohydrolase I was provided in pE147.
To generate a variant of the R. emersonii PC1-147 fusion cellobiohydrolase I (SEQ ID NO: 75 for the mutant DNA sequence and SEQ ID NO: 76 for the variant), an AAC codon (N194) was replaced with a GCA codon (194A) and an AAC codon (N197) was replaced with a GCA codon (197A) in the gene encoding the R. emersonii PC1-147 fusion cellobiohydrolase I.
Two synthetic primers for site-directed mutagenesis were designed as shown below using a SOE primer design tool. The introduced site-directed mutation changed an AAC codon (N194) to a GCA codon (194A) and an AAC codon (N197) to a GCA codon (197A).
Primer F-N194A N197A:
(SEQ ID NO: 67)
5′-AAGGATGGCAGCCCTCGTCCGCAAACGCGGCAACTGGCATCGGTG
ATCAC-3′
Primer R-N194A N197A:
(SEQ ID NO: 68)
5′-GGACGAGGGCTGCCATCCTTCCACGTTCGC-3′
Site-directed mutagenesis of the R. emersonii PC1-147 fusion cellobiohydrolase I gene was facilitated by PCR amplifications of the pDau109 vector containing the R. emersonii PC1-147 fusion cellobiohydrolase I gene. The R. emersonii PC1-147 fusion cellobiohydrolase I gene was previously cloned into Bam HI-Hind III digested pDau109 resulting in transcription of the R. emersonii PC1-147 fusion cellobiohydrolase I gene under the control of a NA2-tpi double promoter.
The mutations were introduced by PCR using a PHUSION® High-Fidelity PCR Kit. The PCR solution was composed of 10 μl of 5× HF buffer, 1 μl of dNTPs (10 mM), 0.5 μl of PHUSION® DNA polymerase (0.2 units/μl), 0.25 μl of primer F-N194A N197A (100 μM), 0.25 μl of primer R-N194A N197A (100 μM), 10 μl of plasmid pE147 DNA (1 ng/μl), and 28 μl of deionized water in a total volume of 50 μl. The PCR was performed using a GeneAmp® PCR System 9700 programmed for 1 cycle at 98° C. for 30 seconds; and 19 cycles each at 98° C. for 30 seconds, 55° C. for 1 minute, and 72° C. for 4 minutes. The PCR solution was then held at 8° C. until removed from the PCR machine.
Following the PCR, 10 units of Dpn I were added directly to the PCR solution and incubated at 37° C. for 1 hour. Then 1 μl of the Dpn I treated PCR solution was transformed into ONE SHOT® TOP10F′ Chemically Competent E. coli cells according to the manufacturer's protocol and spread onto LB plates supplemented with 0.15 mg of ampicillin per ml. After incubation at 37° C. overnight, transformants were observed growing under selection on the LB ampicillin plates. Four transformants were cultivated in LB medium supplemented with 0.15 mg of ampicillin per ml and plasmids were isolated using a QIAPREP® Spin Miniprep Kit.
The isolated plasmids were sequenced using an Applied Biosystems 3730xl DNA Analyzer with primers F-pDau109, F-Central1, R-Central2 and R-pDau109, in order to determine a representative plasmid that was free of PCR errors and contained the desired mutations.
Primer F-pDau109
(SEQ ID NO: 69)
5′-CCACACTTCTCTTCCTTCCTCAATCCTC-3′
Primer F-Central1
(SEQ ID NO: 70)
5′-GTGAGGCGAACGTGGAAGGATG-3′
Primer R-Central2
(SEQ ID NO: 71)
5′-gtacctgtgtccgtgccgtcatctg-3′
Primer R-pDau109
(SEQ ID NO: 31)
5′-ATCCTCAATTCCGTCGGTCGA-3′
One plasmid clone free of PCR errors and containing the AAC (N194) to GCA (194A) mutation and the AAC (N197) to GCA (197A) mutation was chosen and designated plasmid pE378. The variant is designated herein as PC1-378.
Example 32: Expression of the Rasamsonia emersonii PC1-147 Fusion Cellobiohydrolase I and R. emersonii Cellobiohydrolase I PC1-378 Variant
The expression plasmids pE147 and pE378 were transformed into Aspergillus oryzae MT3568 protoplasts according to Christensen et al., 1988, supra and WO 2004/032648. A. oryzae MT3568 protoplasts were prepared according to the method of EP 0238023 B1, pages 14-15.
Transformants were purified on COVE sucrose plates without CsCl through single conidia. Spores of the transformants were inoculated into 96 deep well plates containing 0.50 ml of YP+2% maltose+0.5% glucose medium and incubated stationary at 34° C. for 6 days. Production of the R. emersonii PC1-147 fusion cellobiohydrolase I and the R. emersonii cellobiohydrolase I PC1-378 variant by the transformants were analyzed from culture supernatants of the 96 deep well cultivations. Expression was verified by measuring the released reducing sugars from hydrolysis of microcrystalline cellulose according to the procedure described in Example 23.
Based on the level of hydrolysis of the microcrystalline cellulose one transformant for the R. emersonii PC1-147 fusion cellobiohydrolase I and the R. emersonii cellobiohydrolase I PC1-378 variant were selected and designated A. oryzae PC1-147 and A. oryzae PC1-378, respectively.
For larger scale production, A. oryzae PC1-147 or A. oryzae PC1-378 spores were spread onto COVE sucrose slants and incubated for five days at 37° C. The confluent spore slants were washed twice with 5 ml of G2-Gly medium. The spore suspensions were then used to inoculate 500 ml flasks containing 150 ml of G2-Gly medium. These pre-cultures were incubated at 30° C. with constant shaking at 150 rpm. After one day, each of the pre-cultures was used to inoculate four 500 ml flasks containing 150 ml of DAP-4C medium. At day four post-inoculation, the culture broths were collected by filtration through a bottle top MF75 Supor MachV 0.2 μm PES filter.
Example 33: Purification of the Rasamsonia emersonii PC1-147 Fusion Cellobiohydrolase I and R. emersonii Cellobiohydrolase I PC1-378 Variant
The fermentation broths were filtered through a PES Bottle top filter with a 0.22 μm cut-off. Ammonium sulphate was added to the filtered fermentation broths to a concentration of 1.8 M.
The fermentation broths were purified by HIC/affinity chromatography followed by IEX/affinity chromatography.
In the HIC/affinity chromatographic step, the fermentation broths were applied to a 200 ml Phenyl SEPHAROSE® 6 Fast Flow column (high sub) which had been pre-equilibrated with 1.8 M ammonium sulphate, 25 mM HEPES pH 7.0. After applying the sample, the column was washed with 2 column volumes of 1.8 M ammonium sulphate followed by 1 column volume of 0.54 M ammonium sulphate. The bound proteins were batch eluted with 25 mM HEPES pH 7.0.
The elution of the protein was monitored at 280 nm. Fractions with high 280 nm absorbance were analysed on SDS-PAGE using 12-well NUPAGE® 4-12% Bis-Tris gel for their cellobiohydrolase I content. Fractions with high content of this protein were pooled and collected for further purification. The pooled fractions were desalted on a SEPHADEX™ G-25 (medium) column equilibrated with 25 mM MES pH 6.0. The elution of the protein was monitored at 280 nm and fractions with high absorbance at 280 nm were chosen for the second chromatographic step.
The pooled fractions were applied to the 60 ml RESOURCE™ 15Q column equilibrated with 25 mM MES pH 6.0 and bound proteins were eluted with a linear 100-200 mM sodium chloride gradient for 1.5 column volumes followed by 1.5 column volumes of 300 mM sodium chloride, followed by 1.5 column volumes of 1 M sodium chloride. The elution of the protein was monitored at 280 nm and fractions with high absorbance at 280 nm were analysed on SDS-PAGE.
Fractions with high content of cellobiohydrolase I were pooled.
Example 34: Activity Measurement on Microcrystalline Cellulose of the Rasamsonia Emersonii PC1-147 Fusion Cellobiohydrolase I and the R. emersonii Cellobiohydrolase I PC1-378 Variant
The activity of the purified R. emersonii PC1-147 fusion cellobiohydrolase I and the R. emersonii cellobiohydrolase I PC1-378 variant (Example 33) were compared to the purified wild-type R. emersonii cellobiohydrolase I (Example 24) using washed microcrystalline cellulose as a substrate according to Example 25. Values are shown in relative activity where 100% was set as the activity of R. emersonii wild-type cellobiohydrolase I. The assay conditions were 24 hours incubation at pH 5, 50° C. and 1100 rpm.
The results as shown in FIG. 11 demonstrated that the R. emersonii PC1-147 fusion cellobiohydrolase I and the R. emersonii cellobiohydrolase I PC1-378 variant had an approximately 22% and 44% increase in activity toward microcrystalline cellulose, respectively, compared to the R. emersonii wild-type cellobiohydrolase I.
Example 35: Preparation, Expression, and Purification of the R. emersonii Cellobiohydrolase I PC1-496 Variant
The R. emersonii cellobiohydrolase I variant PC1-496 of the R. emersonii PC1-147 fusion cellobiohydrolase I (supra) was designed with deletions at positions S193*, N194*, and N195* (corresponding to deletions at positions 196, 197, and 198 of SEQ ID NO: 2), and then constructed and expressed using procedures similar to those described above. The variant PC1-496 coding sequence and corresponding amino acid sequence are shown in SEQ ID NOs: 77 and 78, respectively.
The fermentation broths were filtered through PES Bottle top filter with a 0.22 μm cut-off. Ammonium sulphate was added to the filtered fermentation broths to make a 1.8 M solution.
The cellobiohydrolases I were purified by HIC/affinity chromatography followed by IEX/affinity chromatography.
In the HIC/affinity chromatographic step, the fermentation broths were applied to a 200 ml Phenyl SEPHAROSE® 6 Fast Flow column (high sub) (GE Healthcare, Piscataway, N.J., USA) which had been pre-equilibrated with 1.8 M ammonium sulphate, 25 mM HEPES pH 7.0. After applying the sample, the column was washed with 2 CV 1.8 M ammonium sulphate followed by 1 CV 0.54 M ammonium sulphate. The bound proteins were batch eluted with 25 mM HEPES pH 7.0.
The elution of the protein was monitored at 280 nm. Fractions with high 280 nm absorbance were analyzed on SDS-PAGE using 12-well NUPAGE® 4-12% Bis-Tris gel (GE Healthcare, Piscataway, N.J., USA) for their cellobiohydrolase I content. Fractions with high content of this protein were pooled and collected for further purification. The pooled fractions were desalted on a SEPHADEX™ G-25 (medium) column (GE Healthcare, Piscataway, N.J., USA) equilibrated with 25 mM MES pH 6.0. The elution of the protein was monitored at 280 nm and fractions with high absorbance at 280 nm were chosen for the second chromatographic step.
The pooled fractions were applied to the 60 ml RESOURCE™ 15Q column (GE Healthcare, Piscataway, N.J., USA) equilibrated with 25 mM MES pH 6.0 and bound proteins were eluted with a linear 100-200 mM sodium chloride gradient for 1.5 CV followed by 1.5 CV 300 mM sodium chloride, followed by 1.5 CV 1 M sodium chloride. The elution of the protein was monitored at 280 nm and fractions with high absorbance at 280 nm were analyzed on SDS-PAGE.
Fractions with high content of cellobiohydrolase I were pooled.
Example 36: Activity Measurement on Microcrystalline Cellulose on Microcrystalline Cellulose of the Rasamsonia emersonii PC1-147 Fusion Cellobiohydrolase I and the R. emersonii Cellobiohydrolase I PC1-496 Variant
The activity of the purified R. emersonii cellobiohydrolase I PC1-496 variant (Example 35) was compared to purified R. emersonii PC1-147 fusion cellobiohydrolase I using washed microcrystalline cellulose (AVICEL® PH101; Sigma-Aldrich, St. Louis, Mo., USA) as a substrate.
The purified cellobiohydrolase variants were diluted in 50 mM sodium acetate, 2 mM CaCl 2 pH 5. The diluted cellobiohydrolase I variants were added to each well (microwell plate 96F 26960 Thermo scientific). Following washed AVICEL was added to each well and the microtiter plate was quickly transferred to a thermomixer (eppendorf) and incubated for 30 min at 1100 rpm and 25° C. The final concentration of cellobiohydrolase I variants in the reaction was 2.4 μM and the concentration of AVICEL was 24.5 g/l. The reaction was stopped by centrifugation at 3500 rpm for 3 min at 5° C. (Hereaus multifuge 3 S—R). 50 μl supernatants were transferred to PCR sample tubes (Thermoscientific 0.2 ml non-skirtet 96-well PCR plate AB0600). PAHBAH (4-hydroxy-benzhydrazid) (Sigma, H 9882) was dissolved in buffer (0.18 M K—Na-tartrate (Merck, 1.08087) and 0.5 M NaOH) to make a 15 mg/ml solution. 75 μl of the PAHBAH solution was added to the supernatants in the PCR sample tubes.
The PCR sample tubes were placed in a Peltier Thermal Cycler and incubated at 95° C. for 10 min and 20° C. for 5 min. After incubation 100 μl were transferred to a 96 well microtiter plate (microwell plate 96F 26960 Thermo scientific) and the absorbance was measured at 410 nm. For each run a standard was included. The standard used was cellobiose diluted in 50 mM sodium acetate, 2 mM CaCl 2 pH 5 to a concentration of 0.008, 0.016, 0.0312, 0.0625, 0.125, 0.25, 0.5 mM. In addition to the standard, a blank (without cellobiohydrolases) was included. For all the measurement, the blank measurement was subtracted. The absorbance data were normalized to cellobiose concentration using the standards.
The results as shown in FIG. 12 demonstrated that the cellobiohydrolase variant PC1-496 (comprising deletions at positions corresponding to 196, 197, and 198 of SEQ ID NO: 2) had an approximately 119% increase in activity toward microcrystalline cellulose compared to the wild-type cellobiohydrolase I at 25° C. and an increase of 54% compared with the R. emersonii PC1-147 fusion cellobiohydrolase I.
Example 37: Pretreated Corn Stover Hydrolysis Assay
Corn stover was pretreated at the U.S. Department of Energy National Renewable Energy Laboratory (NREL) using 1.4 wt % sulfuric acid at 165° C. and 107 psi for 8 minutes. The water-insoluble solids in the pretreated corn stover (PCS) contained 56.5% cellulose, 4.6% hemicellulose, and 28.4% lignin. Cellulose and hemicellulose were determined by a two-stage sulfuric acid hydrolysis with subsequent analysis of sugars by high performance liquid chromatography using NREL Standard Analytical Procedure #002. Lignin was determined gravimetrically after hydrolyzing the cellulose and hemicellulose fractions with sulfuric acid using NREL Standard Analytical Procedure #003.
Unmilled, unwashed PCS (whole slurry PCS) was prepared by adjusting the pH of the PCS to 5.0 by addition of 10 M NaOH with extensive mixing, and then autoclaving for 20 minutes at 120° C. The dry weight of the whole slurry PCS was 29%.
A 96-well plate was generated by machining a teflon plate of depth ¼ inch with 96, cone-shaped wells, diameter ¼ inch at the upper surface and diameter ⅛ inch at the lower surface. The center of each well was at an equivalent position to the center of a corresponding well in a standard 96-well microtiter plate, approximately 23/64 inch on center. The resulting volume of each well was approximately 135 μl. This 96-well aluminum plate is hereinafter referred to as the “fill plate”. The pH-adjusted corn stover was used to fill the holes in the fill plate by applying a suitable volume of the corn stover to the upper surface of the plate, then using a spatula to spread the material over the surface and into the holes. Holes were deemed sufficiently full when corn stover was extruded through the hole in the bottom surface, forming noodle-like tubes. A MULTISCREEN® Column Loader Scraper (Millipore) held perpendicular to the fill plate surface was used to scrape excess corn stover from the top and bottom surfaces of the fill plate, leaving the surfaces of the corn stover in each well flush with the surfaces of the fill plate. The fill plate was then placed on the top of a 2.2 ml deep well plate (Axygen, Union City, Calif., USA) with the top surface adjacent to the open end of the well plate (e.g. the top of the well plate), and the wells aligned with the corn stover-filled holes in the fill plate. The fill plate was secured in this position, and the assembly centrifuged at 2500 rpm (1350× g) for 5 minutes in a Sorvall Legend RT+(Thermo Scientific, Waltham, Mass., USA). Following centrifugation, the corn stover had been transferred to the deep well plate. A 3 mm glass bead (Fisher Scientific, Waltham, Mass., USA) was placed in each well for mixing.
The hydrolysis of PCS was conducted in a total reaction volume of 0.2 ml. The hydrolysis was performed with 50 mg of insoluble PCS solids containing 50 mM sodium acetate pH 5.0 buffer containing 1 mM manganese sulfate and various protein loadings of various enzyme compositions (expressed as mg protein per gram of cellulose). Enzyme compositions were prepared and then added simultaneously to all wells in a volume ranging from 20 μl to 50 μl, for a final volume of 0.2-0.50 ml in each reaction. The plate was then sealed using an ALPS-300™ plate heat sealer (Abgene, Epsom, United Kingdom), mixed thoroughly, and incubated at a specific temperature for 72 hours.
Following hydrolysis, samples were filtered using a 0.45 μm MULTISCREEN® 96-well filter plate (Millipore, Bedford, Mass., USA) and filtrates analyzed for sugar content as described below. When not used immediately, filtered aliquots were frozen at −20° C. The sugar concentrations of samples diluted in 0.005 M H 2 SO 4 were measured using a 4.6×250 mm AMINEX® HPX-87H column (Bio-Rad Laboratories, Inc., Hercules, Calif., USA) by elution with 0.05% w/w benzoic acid-0.005 M H 2 SO 4 at 65° C. at a flow rate of 0.6 ml per minute, and quantitation by integration of the glucose, cellobiose, and xylose signals from refractive index detection (CHEMSTATION®, AGILENT® 1100 HPLC, Agilent Technologies, Santa Clara, Calif., USA) calibrated by pure sugar samples. The resultant glucose and cellobiose equivalents were used to calculate the percentage of cellulose conversion for each reaction.
Glucose and cellobiose were measured individually. Measured sugar concentrations were adjusted for the appropriate dilution factor. The net concentrations of enzymatically-produced sugars from unwashed PCS were determined by adjusting the measured sugar concentrations for corresponding background sugar concentrations in unwashed PCS at zero time point. All HPLC data processing was performed using MICROSOFT EXCEL™ software (Microsoft, Richland, Wash., USA).
The degree of glucose conversion to glucose was calculated using the following equation: % cellulose conversion=(glucose concentration)/(glucose concentration in a limit digest)×100. In order to calculate % glucose conversion, a 100% conversion point was set based on a cellulase control (100 mg of T. reesei cellulase supplemented with Thermoascus aurantiacus GH61A polypeptide, Aspergillus fumigatus GH10 xylanase (xyn3), and Talaromyces emersonii beta-xylosidase per gram cellulose). Quadruplicate data points were averaged and standard deviation was calculated.
Example 38: Preparation of an Enzyme Composition #3 without Cellobiohydrolase I
The Talaromyces leycettanus GH6 cellobiohydrolase II (GENESEQP:AZY49446) was prepared recombinantly in Aspergillus oryzae as described in WO 2012/103288. The filtered broth of the Talaromyces leycettanus GH6 cellobiohydrolase II was concentrated and buffer exchanged into 20 mM Tris pH 8.0 using a 400 ml SEPHADEX™ G-25 column (GE Healthcare, United Kingdom). The fractions were pooled, and 3 M ammonia sulfate, 20 mM Tris pH 8.0 was added to the desalted protein to a final concentration of 1.2 M ammonia sulfate, 20 mM Tris pH 8.0. The protein was loaded onto a Phenyl Sepharose™ 6 Fast Flow column (high sub) (GE Healthcare, Piscataway, N.J., USA) equilibrated in 20 mM Tris pH 8.0 with 1.2 M ammonium sulfate, and bound proteins were eluted with 20 mM Tris pH 8.0 with no ammonium sulfate. Fractions were analyzed by 8-16% Tris-HCl SDS-PAGE gels (Bio-Rad, Hercules, Calif., USA), and pooled. The pooled protein was buffer exchanged into 20 mM MES pH 6.0 using a Vivaflow 200 with 10 kDa molecular weight cut-off tangential flow membrane (Sartorius, Bohemia, N.Y., USA).
The Trichoderma reesei GH5 endoglucanase II (GENESEQP:AZI04858) was prepared recombinantly according to WO 2011/057140 using Aspergillus oryzae as a host. The filtered broth of the T. reesei endoglucanase II was desalted and buffer-exchanged into 20 mM Tris pH 8.0 using a tangential flow concentrator (Pall Filtron, Northborough, Mass., USA) equipped with a 10 kDa polyethersulfone membrane (Pall Filtron, Northborough, Mass., USA).
Thermoascus aurantiacus CGMCC 0583 GH61A polypeptide having cellulolytic enhancing activity (GENESEQP:AEC05922) was recombinantly prepared according to WO 2005/074656 using Aspergillus oryzae JaL250 as a host. The broth was filtered using a 0.22 μm EXPRESS™ Plus Membrane (Millipore, Bedford, Mass., USA).
The Aspergillus fumigatus GH10 xylanase (xyn3) (GENESEQP:AZI04884) was prepared recombinantly according to WO 2006/078256 using Aspergillus oryzae BECh2 (WO 2000/39322) as a host. The filtered broth of the A. fumigatus xylanase was desalted and buffer-exchanged into 50 mM sodium acetate pH 5.0 using a HIPREP® 26/10 Desalting Column (GE Healthcare, Piscataway, N.J., USA).
The Aspergillus fumigatus Cel3A beta-glucosidase 4M mutant (GENESEQP:AZU67153) was recombinantly prepared according to WO 2012/044915. The filtered broth of Aspergillus fumigatus Cel3A beta-glucosidase 4M was concentrated and buffer exchanged using a tangential flow concentrator (Pall Filtron, Northborough, Mass., USA) equipped with a 10 kDa polyethersulfone membrane (Pall Filtron, Northborough, Mass., USA) with 50 mM sodium acetate pH 5.0 containing 100 mM sodium chloride.
The Talaromyces emersonii CBS 393.64 beta-xylosidase (GENESEQP:AZI04896) was prepared recombinantly according to Rasmussen et al., 2006 , Biotechnology and Bioengineering 94: 869-876 using Aspergillus oryzae JaL355 as a host (WO 2003/070956). The filtered broth was concentrated and desalted with 50 mM sodium acetate pH 5.0 using a tangential flow concentrator equipped with a 10 kDa polyethersulfone membrane (Pall Filtron, Northborough, Mass., USA).
The protein concentration for each of the monocomponents described above was determined using a Microplate BCA™ Protein Assay Kit (Thermo Fischer Scientific, Waltham, Mass., USA) in which bovine serum albumin was used as a protein standard. An enzyme composition was prepared composed of each monocomponent as follows: 39.7% Talaromyces leycettanus GH6 cellobiohydrolase II, 15.9% Trichoderma reesei GH5 endoglucanase II, 23.8% Thermoascus aurantiacus GH61A polypeptide, 7.9% Aspergillus fumigatus GH10 xylanase, 7.9% Aspergillus fumigatus beta-glucosidase, and 4.8% Talaromyces emersonii beta-xylosidase. The enzyme composition is designated herein as “cellulolytic enzyme composition #3 without cellobiohydrolase I”.
Example 39: Comparison of the Effect of the Rasamsonia emersonii PC1-147 Fusion Cellobiohydrolase I and the R. emersonii Cellobiohydrolase I PC1-496 Variant on the Hydrolysis of Unwashed PCS by a Cellulase Enzyme Composition
The R. emersonii cellobiohydrolase I PC1-496 variant (Example 35) was added to the cellulolytic enzyme composition #3 without cellobiohydrolase I (Example 39) at 35° C., 50° C., and 60° C. using unwashed PCS as a substrate, and compared against the R. emersonii PC1-147 fusion cellobiohydrolase I added to the cellulolytic enzyme composition #3 without cellobiohydrolase I. Each cellobiohydrolase I was added individually at 3.33 mg enzyme protein per g cellulose to 5.67 mg enzyme protein of the cellulase enzyme composition #3 without cellobiohydrolase I per g cellulose.
The assay was performed as described supra. The reactions with unwashed PCS (20% total solids) were conducted for 72 hours at 35° C., 50° C., and 60° C. in 50 mM sodium acetate pH 5.0 buffer containing 1 mM manganese sulfate. All reactions were performed in quadruplicate and shaking at 200 rpm throughout the hydrolysis.
The results shown in FIG. 13 demonstrated that the cellulase enzyme composition containing the R. emersonii cellobiohydrolase I PC1-496 variant had significantly higher cellulose conversion than the cellulase enzyme composition that included R. emersonii PC1-147 fusion cellobiohydrolase I at 35° C.
Example 40: Preparation, Expression, and Purification of the Trichoderma reesei Cellobiohydrolase I Variants TC1-213 and TC1-216
The Trichoderma reesei cellobiohydrolase I variant TC1-213 of the Trichoderma reesei wild-type GH7 cellobiohydrolase I of SEQ ID NO: 2 was designed with deletions at positions N197* and N198*, and then constructed and expressed using procedures similar to those described above. The variant TC1-213 coding sequence and corresponding amino acid sequence are shown in SEQ ID NOs: 79 and 80 respectively.
The Trichoderma reesei cellobiohydrolase I variant TC1-216 of the Trichoderma reesei wild-type GH7 cellobiohydrolase I of SEQ ID NO: 2 was designed with deletions at positions S195* and S196*, and then constructed and expressed using procedures similar to those described above. The variant TC1-216 coding sequence and corresponding amino acid sequence are shown in SEQ ID NOs: 81 and 82, respectively.
Two synthetic primers for each site-directed mutagenesis were designed as below using the SOE primer design tool. Primers F-N197* N198* and R-N197* N198* were used to generate the deletions of variant TC1-213. Primers F-S195* S196* and R-S195* S196* were used to generate the deletions of variant TC1-216.
Primer F-N197* N198*:
(SEQ ID NO: 83)
5′-AAGGC TGGGA ACCCT CGTCG GCCAA CACCG GCATT
GGAGG-3′
Primer R-N197* N198*:
(SEQ ID NO: 84)
5′-CGACG AGGGT TCCCA GCCTT CGACG TTTGC C-3′
Primer F-S195* S196*:
(SEQ ID NO: 85)
5′-ACGTC GAAGG CTGGG AACCC AACAA CGCCA ACACC
GGCAT TG-3′
Primer R-S195* S196*:
(SEQ ID NO: 86)
5′-GGGTT CCCAG CCTTC GACGT TTGCC TGGCC-3′
The variants were constructed using the plasmid pKHJN0036 (Example 3) which contains the codon optimized gene encoding the Trichoderma reesei cellobiohydrolase I, and then expressed and purified using procedures as described above in Examples 2, 5 and 7.
Example 41: Comparison of the Effect of Trichoderma reesei Cellobiohydrolase I TC1-213 Variant Polypeptides (TC1-213 and TC1-216) Against Trichoderma reesei Cellobiohydrolase I Wild-Type on the Hydrolysis of Unwashed PCS by a Cellulase Enzyme Composition
The Trichoderma reesei variant polypeptides TC1-213 and TC1-216 from Example 40 (corresponding to a deletion of N197+N198 and S195+S196 respectively) were added to the cellulolytic enzyme composition without cellobiohydrolase I (Example 38) at 35° C. using unwashed PCS as a substrate, and compared against the Trichoderma reesei cellobiohydrolase I wild-type polypeptide. Each cellobiohydrolase I was added individually at 2, 3, and 4 mg enzyme protein per g cellulose to 5.108 mg enzyme protein of the cellulase enzyme composition without cellobiohydrolase I per g cellulose.
The assay was performed as described in Example 37. The reactions with unwashed PCS (20% total solids) were conducted for 72 hours at 35° C. in 80 mM sodium acetate pH 5.0 buffer containing 1 mM manganese sulfate. All reactions were performed in quadruplicate and shaking at 200 rpm throughout the hydrolysis.
The results shown in FIG. 14 demonstrated that the cellulase enzyme composition containing the variant polypeptide TC1-213 had significantly higher cellulose conversion at 35° C. compared to the cellulase enzyme composition that included the Trichoderma reesei cellobiohydrolase I wild-type at 2 mg enzyme protein per g cellulose only. In addition, the cellulase enzyme composition containing the variant polypeptide TC1-216 had significantly higher cellulose conversion at 35° C. compared to the cellulase enzyme composition that included the Trichoderma reesei cellobiohydrolase I wild-type at all protein loadings.
Example 42: Source of DNA Sequence Information for Aspergillus fumigatus Cellobiohydrolase I
The genomic DNA sequence and deduced amino acid sequence of the Aspergillus fumigatus Af293 GH7 cellobiohydrolase I gene is shown in SEQ ID NO: 87 and SEQ ID NO: 8, respectively. Genomic sequence information was generated by The Institute for Genomic Research, Rockville, Md. 20850, USA and published by Nierman, W. C. et al., 2005 , Nature 438 (7071): 1151-1156. The amino acid sequence of the full-length cellobiohydrolase I is publicly available from the National Center for Biotechnology Information (NCBI) and annotated as GenBank: EAL89006.1 The cDNA sequence and deduced amino acid sequence of the Aspergillus fumigatus cellobiohydrolase I gene is shown in SEQ ID NO: 88 and SEQ ID NO: 8, respectively.
Based on the publicly available amino acid sequence, a codon-optimized synthetic gene encoding the full-length cellobiohydrolase I was generated for Aspergillus oryzae expression based on the algorithm developed by Gustafsson et al., 2004 , Trends in Biotechnology 22 (7): 346-353. The codon-optimized coding sequence (SEQ ID NO: 89) was synthesized by the GENEART® Gene Synthesis service (Life Technologies Corp., San Diego. Calif., USA) with a 5′ Bam HI restriction site, a 3′ Hind III restriction site, and a Kozac consensus sequence (CACC) situated between the start codon and the Bam HI restriction site.
Example 43: Construction of an Aspergillus oryzae Expression Vector Containing an Aspergillus fumigatus DNA Sequence Encoding Cellobiohydrolase I
The ampicillin-resistant E. coli cloning vector provided by GENEART® Gene Synthesis encoding the A. fumigatus cellobiohydrolase I (Example 14) was digested with Barn HI and Hind III (New England Biolabs, MA, USA) according to manufacturer's instructions. The reaction products were isolated by 1.0% agarose gel electrophoresis using TAE buffer where a 1606 bp product band was excised from the gel and purified using a MinElute Gel Extraction Kit (QIAGEN Inc., Valencia, Calif., USA).
The purified 1606 bp fragment encoding the A. fumigatus cellobiohydrolase I was cloned into pDau109 (WO 2005/042735) digested with Bam HI and Hind III using T4 DNA ligase (New England Biolabs, MA, USA). The Bam HI-Hind III digested pDau109 and the Barn HI/Hind III fragment containing the A. fumigatus cellobiohydrolase I were mixed in a molar ratio of 1:3 (i.e., equal volumes of gel purified products) and ligated with 50 units of T4 DNA ligase in 1× T4 DNA ligase buffer with 1 mM ATP and incubated at 22° C. for 10 minutes.
Cloning of the A. fumigatus cellobiohydrolase I gene into the Bam HI-Hind III digested pDau109 will result in transcription of the A. fumigatus cellobiohydrolase I gene under the control of a NA2-tpi double promoter. The NA2-tpi promoter is a modified promoter from the gene encoding the Aspergillus niger neutral alpha-amylase in which the untranslated leader has been replaced by an untranslated leader from the gene encoding the Aspergillus nidulans triose phosphate isomerase.
The ligation mixture was transformed into ONE SHOT® TOP10F′ Chemically Competent E. coli cells according to the manufacturer's protocol and spread onto LB plates supplemented with 0.1 mg of ampicillin per ml. After incubation at 37° C. overnight, colonies were observed growing under selection on the LB ampicillin plates.
Insertion of the A. fumigatus cellobiohydrolase I gene into pDau109 was verified by DNA sequencing. The isolated plasmids were sequenced using an Applied Biosystems 3730xl DNA Analyzer with vector primers and A. fumigatus cellobiohydrolase I gene specific primers, shown below, in order to determine a representative plasmid that was free of PCR errors and contained the desired insert.
Primer F-pDau109
(SEQ ID NO: 90)
5′-CCCTT GTCGA TGCGA TGTAT C-3′
Primer R-pDau109
(SEQ ID NO: 91)
5′-ATCCT CAATT CCGTC GGTCG A-3′
Primer F-pE596
(SEQ ID NO: 92)
5′-GTGAT ACACC CGGAC AGGTG ATGTG-3′
Primer R-pE596
(SEQ ID NO: 93)
5′-CCATA TCGAT CCGAC GAGTA GGTTC-3′
An E. coli transformant containing the A. fumigatus cellobiohydrolase I plasmid construct was cultivated in LB medium supplemented with 0.1 mg of ampicillin per ml and plasmid DNA was isolated using a QIAPREP® Spin Miniprep Kit. The plasmid was designated pE596 and the corresponding polypeptide was designated as AC1-596.
Example 44: Site-Directed Mutagenesis of the Aspergillus fumigatus Cellobiohydrolase I (AC1-865)
Plasmid pE596 (Example 43) was used to generate the A. fumigatus cellobiohydrolase I AC1-865 variant (SEQ ID NO: 94 for the mutant DNA sequence and SEQ ID NO: 95 for the variant), where three codons TCG AAC GAT were deleted (S196 N197 D198) to give S196* N197* D198* (corresponding to deletions at positions 196, 197, and 198 of SEQ ID NO: 2).
Two synthetic primers for site-directed mutagenesis were designed using a SOE primer design tool. Site-directed mutagenesis of the synthetic gene encoding the wild-type A. fumigatus cellobiohydrolase I was facilitated by PCR amplifications of pE596 using the primers and procedure described below:
Primer F-S196* N197* D198*:
(SEQ ID NO: 96)
5′-TCGAG GGTTG GCAGC CTTCG GCCAA CGCAG GTACC GGCAA
C-3′
Primer R-S196* N197* D198*:
(SEQ ID NO: 97)
5′-CGAAG GCTGC CAACC CTCGA CGTTG GCCTG-3′
The mutations were introduced by PCR using a PHUSION® High-Fidelity PCR Kit (New England Biolabs, MA, USA). The PCR solution was composed of 10 μl of 5× HF buffer (New England Biolabs, MA, USA), 4 μl of dNTPs (2.5 mM), 0.5 μl of PHUSION® DNA polymerase (0.2 units/μl) (New England Biolabs, MA, USA), 0.25 μl of primer F-S196* N197* D198* (100 μM), 0.25 μl of primer R-S196* N197* D198* (100 μM), 5 μl of template DNA (pE596, 1 ng/μl), and 30 μl of deionized water in a total volume of 50 μl. The PCR was performed using an Applied Biosystems® Veriti® 96 well thermal cycler programmed for 1 cycle at 98° C. for 30 seconds; and 19 cycles each at 98° C. for 30 seconds, 55° C. for 1 minute, and 72° C. for 7 minutes. The PCR solution was then held at 8° C. until removed from the PCR machine.
Following the PCR, 10 units of Dpn I were added directly to the PCR solution and incubated at 37° C. for 1 hour. Then 1 μl of the Dpn I treated PCR solution was transformed into ONE SHOT® TOP10F′ Chemically Competent E. coli cells according to the manufacturer's protocol and spread onto LB plates supplemented with 0.15 mg of ampicillin per ml. After incubation at 37° C. overnight, transformants were observed growing under selection on the LB ampicillin plates. Four transformants were cultivated in LB medium supplemented with 0.10 mg of ampicillin per ml and plasmids were isolated using a QIAPREP® Spin Miniprep Kit (QIAGEN Inc., Valencia, Calif., USA).
The isolated plasmids were sequenced using an Applied Biosystems 3730xl DNA Analyzer (Applied Biosystems, Foster City, Calif., USA) with primers F-pDau109 (SEQ ID NO: 30), R-pDau109 (SEQ ID NO: 310), F-pE596 (SEQ ID NO: 92) and R-pE596 (SEQ ID NO: 93), in order to determine a representative plasmid that was free of PCR errors and contained the desired mutations.
Primer F-pDau109:
(SEQ ID NO: 30)
5′-CCCTT GTCGA TGCGA TGTAT C-3′
Primer R-pDau109:
(SEQ ID NO: 31)
5′-ATCCT CAATT CCGTC GGTCG A-3′
Primer F-pE596:
(SEQ ID NO: 92)
5′-GTGAT ACACC CGGAC AGGTG ATGTG-3′
Primer R-pE596:
(SEQ ID NO: 93)
5′-CCATA TCGAT CCGAC GAGTA GGTTC-3′
One plasmid clone free of PCR errors and containing the deletion of codons TCG AAC GAT (S196* N197* D198*) was chosen and designated plasmid pE865 and the corresponding polypeptide was designated as AC1-865.
Generating the Aspergillus oryzae strain expressing the AC1-865 variant and the AC1-596 wild type were done using the same method as described in Example 5. Based on the level of hydrolysis of the microcrystalline cellulose one transformant expressing the A. fumigatus cellobiohydrolase I variant AC1-865 was selected and designated A. oryzae AC1-865 and one transformant expressing the wild type A. fumigatus cellobiohydrolase I was selected and designated A. oryzae AC1-596.
Purification of the wild-type Aspergillus fumigatus cellobiohydrolase I AC1-596 and the variant AC1-865 were done essentially as described in Example 7.
Example 45: Activity Measurement on Microcrystalline Cellulose of the Variant AC1-865 and the Wild-Type Aspergillus fumigatus Cellobiohydrolase I
The activity of the purified variant polypeptide AC1-865 was compared to the purified wild-type A. fumigatus cellobiohydrolase I AC1-596 using washed microcrystalline cellulose (AVICEL® PH101; Sigma-Aldrich, St. Louis, Mo., USA) as a substrate (see PCT/US2014/022068).
The purified cellobiohydrolases were diluted in 50 mM sodium acetate, 2 mM CaCl 2 pH 5. The diluted cellobiohydrolases and β-glucosidase were added to each well (microwell plate 96F 26960 Thermo scientific). Washed AVICEL then was added to each well and the microtiter plate was quickly transferred to a thermomixer (eppendorf) and incubated for 24 hours at 1100 rpm and 35° C. or 55° C. The final concentration of the cellobiohydrolases in the reaction was 3 μM and the concentration of AVICEL was 80 g/l. The reaction was stopped by centrifugation at 3500 rpm for 3 min at 5° C. (Hereaus multifuge 3 S-R). The supernatants are diluted 40 times and 50 μL of diluted supernatants were transferred to PCR sample tubes (Thermoscientific 0.2 ml non-skirtet 96-well PCR plate AB0600). PAHBAH (4-hydroxy-benzhydrazid) (Sigma, H 9882) was dissolved in buffer (0.18 M K—Na-tartrate (Merck, 1.08087) and 0.5 M NaOH) to make a 15 mg/ml solution. Seventy-five μL of the PAHBAH solution was added to the supernatants in the PCR samples tubes.
The PCR sample tubes were placed in a Peltier Thermal Cycler and incubated at 95° C. for 10 min and 20° C. for 5 min. After incubation 100 μl were transferred to a 96 well microtiter plate (microwell plate 96F 26960 Thermo scientific) and the absorbance was measured at 410 nm. For each run a standard was included. The standard used was glucose diluted in 50 mM sodium acetate, 2 mM CaCl2 pH 5 to a concentration of 0.008, 0.016, 0.0312, 0.0625, 0.125, 0.25 and 0.5 mM. In addition to the standard, a blank (without cellobiohydrolase) for each run was included. For all the measurement, the blank measurement was subtracted. The absorbance data were normalized to glucose concentration using the standards.
The results as shown in FIG. 15 demonstrated that at 35° C., the variant AC1-865 (with a deletion of S196 N197 and D198) had an approximately 23% increase toward microcrystalline cellulose compared to the wild-type cellobiohydrolase I.
The invention described and claimed herein is not to be limited in scope by the specific aspects herein disclosed, since these aspects are intended as illustrations of several aspects of the invention. Any equivalent aspects are intended to be within the scope of this invention. Indeed, various modifications of the invention in addition to those shown and described herein will become apparent to those skilled in the art from the foregoing description. Such modifications are also intended to fall within the scope of the appended claims. In the case of conflict, the present disclosure including definitions will control.
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