# Patent

## Title
Methods for determining cellulolytic enhancing activity of a polypeptide

## Abstract

The present invention relates to methods for determining cellulolytic enhancing activity of a polypeptide, comprising: (a) incubating a cellulosic material with an enzyme composition comprising a cellobiose dehydrogenase and one or more cellulolytic enzymes in the presence and absence of the polypeptide; and (b) measuring the release of sugar from the cellulosic material in the presence and absence of the polypeptide.

## Background
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the benefit of U.S. Provisional Application No. 61/139,256, filed Dec. 19, 2008, which application is incorporated herein by reference.


REFERENCE TO A SEQUENCE LISTING
This application contains a Sequence Listing filed electronically by EFS, which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to methods for determining cellulolytic enhancing activity of polypeptides.
2. Description of the Related Art
Cellulose is a polymer of the simple sugar glucose 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 or other fermentation products.
WO 2005/074647 discloses isolated polypeptides having cellulolytic enhancing activity and polynucleotides thereof from Thielavia terrestris. WO 2005/074656 discloses an isolated polypeptide having cellulolytic enhancing activity and the polynucleotide thereof from Thermoascus aurantiacus. WO 2007/089290 discloses an isolated polypeptide having cellulolytic enhancing activity and the polynucleotide thereof from Trichoderma reesei. Such polypeptides enhance the activity of cellulolytic enzyme compositions in the hydrolysis of lignocellulosic feedstocks.
Current methods for evaluating whether a polypeptide has cellulolytic enhancing activity involve direct addition to cellulase compositions in the hydrolysis of process relevant pretreated biomass substrates. This has the disadvantage of high sample usage, limited sensitivity (lower signal to noise), and potential for variable results due to lot-to-lot variation in pretreated biomass.
There is a need in the art for improved methods that allow the identification and quantification of proteins that can enhance the hydrolysis of cellulosic materials by cellulolytic enzyme compositions.
The present invention provides methods for determining cellulolytic enhancing activity of a polypeptide.
SUMMARY OF THE INVENTION
The present invention relates to methods for determining cellulolytic enhancing activity of a polypeptide, comprising:
(a) incubating a cellulosic material with an enzyme composition comprising a cellobiose dehydrogenase and one or more (several) cellulolytic enzymes in the presence and absence of the polypeptide; and
(b) measuring the release of sugar from the cellulosic material in the presence and absence of the polypeptide.



BRIEF DESCRIPTION OF THE FIGURES
FIGS. 1A and 1B show the genomic DNA sequence and the deduced amino acid sequence of a Myceliophthora thermophila CBS 202.75 Cel6A cellobiohydrolase II gene (SEQ ID NOs: 47 and 48, respectively).
FIG. 2 shows a restriction map of pSMai180.
FIG. 3 shows a restriction map of pSMai182.
FIG. 4 shows the effect of Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity and Myceliophthora thermophila cellobiose dehydrogenase on the conversion of microcrystalline cellulose by Trichoderma reesei CEL7A cellobiohydrolase I, Trichoderma reesei CEL6A cellobiohydrolase II, Trichoderma reesei CEL5A endoglucanase II, or Myceliophthora thermophila Cel6A cellobiohydrolase II.
FIG. 5 shows the effect of Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity and Humicola insolens cellobiose dehydrogenase on the conversion of microcrystalline cellulose by each of three individual cellulases, Trichoderma reesei CEL7A cellobiohydrolase I, Trichoderma reesei CEL5A endoglucanase II, or Aspergillus oryzae CEL3A beta-glucosidase, or binary combinations of two cellulases, Trichoderma reesei CEL7A cellobiohydrolase I combined with Trichoderma reesei CEL5A endoglucanase II, or Aspergillus oryzae CEL3A beta-glucosidase combined with Trichoderma reesei CEL5A endoglucanase II.
FIG. 6 shows the effect of Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity and Thielavia terrstris GH61E protein having cellulolytic enhancing activity on the conversion of microcrystalline cellulose by a combination of Aspergillus oryzae CEL3A beta-glucosidase and Trichoderma reesei CEL5A endoglucanase II, either in the presence or absence of Humicola insolens cellobiose dehydrogenase.
FIG. 7 shows the effect of Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity, Thielavia terrstris GH61E polypeptide having cellulolytic enhancing activity, and Thielavia terrstris GH61E H19N variant having no cellulolytic enhancing activity on the conversion of microcrystalline cellulose by a combination of Aspergillus oryzae CEL3A beta-glucosidase and Trichoderma reesei CEL5A endoglucanase II, either in the presence or absence of Humicola insolens cellobiose dehydrogenase.



DEFINITIONS
Cellulolytic enhancing activity: The term “cellulolytic enhancing activity” is defined herein as a biological activity that enhances the hydrolysis of a cellulosic material by proteins having cellulolytic activity. In a preferred aspect, the polypeptide having cellulolytic enhancing activity is a Family 61 polypeptide.
Family 61 glycoside hydrolase: The term “Family 61 glycoside hydrolase” or “Family GH61” is defined herein as a polypeptide falling into the glycoside hydrolase Family 61 according to Henrissat B., 1991, A classification of glycosyl hydrolases based on amino-acid sequence similarities, Biochem. J. 280: 309-316, and Henrissat B., and Bairoch A., 1996, Updating the sequence-based classification of glycosyl hydrolases, Biochem. J. 316: 695-696. Presently, Henrissat lists the GH61 Family as unclassified indicating that properties such as mechanism, catalytic nucleophile/base, and catalytic proton donors are not known for polypeptides belonging to this family.
Cellobiose dehydrogenase: The term “cellobiose dehydrogenase” is defined herein as a cellobiose:acceptor 1-oxidoreductase (E.C. 1.1.99.18) that catalyzes the conversion of cellobiose in the presence of an acceptor to cellobiono-1,5-lactone and a reduced acceptor. 2,6-Dichloroindophenol can act as acceptor, as can iron, especially Fe(SCN)3, molecular oxygen, ubiquinone, or cytochrome C, and likely many other polyphenolics. Substrates of the enzyme include cellobiose, cello-oligosaccharides, lactose, and D-glucosyl-1,4-β-D-mannose, glucose, maltose, mannobiose, thiocellobiose, galactosyl-mannose, xylobiose, and xylose. Electron donors are preferably beta-1-4 dihexoses with glucose or mannose at the reducing end, though alpha-1-4 hexosides, hexoses, pentoses, and beta-1-4 pentomers have also been shown to act as substrates for these enzymes (Henriksson et al, 1998, Biochimica et Biophysica Acta—Protein Structure and Molecular Enzymology; 1383: 48-54; and Schou et al, 1998, Biochem. J. 330: 565-571).
Cellobiose dehydrogenases comprise two families, 1 and 2, differentiated by the presence of a cellulose binding motif (CBM). The 3-dimensional structure of cellobiose dehydrogenase features two globular domains, each containing one of two cofactors: a heme or a flavin. The active site lies at a cleft between the two domains. The catalytic cycle of cellobiose dehydrogenase follows an ordered sequential mechanism. Oxidation of cellobiose occurs via 2-electron transfer from cellobiose to the flavin, generating cellobiono-1,5-lactone and reduced flavin. The active FAD is regenerated by electron transfer to the heme group, leaving a reduced heme. The native state heme is regenerated by reaction with the oxidizing substrate at the second active site.
The oxidizing substrate is preferentially iron ferricyanide, cytochrome C, or an oxidized phenolic compound such as dichloroindophenol (DCIP), a substrate commonly used for colorimetric assays. Metal ions and O2 are also substrates, but for most cellobiose dehydrogenases the reaction rate for these substrates is several orders of magnitude lower than that observed for iron or organic oxidants. Following cellobionolactone release, the product may undergo spontaneous ring-opening to generate cellobionic acid (Hallberg et al., 2003, J. Biol. Chem. 278: 7160-7166).
Cellulolytic activity: The term “cellulolytic activity” is defined herein as a biological activity that hydrolyzes a cellulosic material. The two basic approaches for measuring cellulolytic activity include: (1) measuring the total cellulolytic activity, and (2) measuring the individual cellulolytic activities (endoglucanases, cellobiohydrolases, and beta-glucosidases) as reviewed in Zhang et al., Outlook for cellulase improvement: Screening and selection strategies, 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, Measurement of cellulase activities, Pure Appl. Chem. 59: 257-68).
For purposes of the present invention, cellulolytic activity is determined by measuring the increase in hydrolysis of a cellulosic material by cellulolytic enzyme(s) under the following conditions: 1-20 mg of cellulolytic protein/g of cellulose in PCS for 3-7 days at 50-65° C. compared to a control hydrolysis without addition of cellulolytic protein. Typical conditions are 1 ml reactions, washed or unwashed PCS, 5% insoluble solids, 50 mM sodium acetate pH 5, 1 mM MnSO4, 50-65° C., 72 hours, sugar analysis by AMINEX® HPX-87H column (Bio-Rad Laboratories, Inc., Hercules, Calif., USA).
Endoglucanase: The term “endoglucanase” is defined herein as an endo-1,4-(1,3;1,4)-beta-D-glucan 4-glucanohydrolase (E.C. 3.2.1.4), which catalyses 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 glucans such as cereal beta-D-glucans or xyloglucans, and other plant material containing cellulosic components. Endoglucanase activity can be determined based on a 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) hydrolysis according to the procedure of Ghose, 1987, Pure and Appl. Chem. 59: 257-268.
Cellobiohydrolase: The term “cellobiohydrolase” is defined herein as a 1,4-beta-D-glucan cellobiohydrolase (E.C. 3.2.1.91), which 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 or non-reducing ends of the chain (Teeri, 1997, Crystalline cellulose degradation: New insight into the function of cellobiohydrolases, Trends in Biotechnology 15: 160-167; Teen et al., 1998, Trichoderma reesei cellobiohydrolases: why so efficient on crystalline cellulose?, Biochem. Soc. Trans. 26: 173-178). For purposes of the present invention, cellobiohydrolase activity is determined using a fluorescent disaccharide derivative 4-methylumbelliferyl-β-D-lactoside according to the procedures described by van Tilbeurgh et al., 1982, FEBS Letters 149: 152-156 and van Tilbeurgh and Claeyssens, 1985, FEBS Letters 187: 283-288.
Beta-glucosidase: The term “beta-glucosidase” is defined herein as a beta-D-glucoside glucohydrolase (E.C. 3.2.1.21), which 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 according to the basic procedure described by Venturi et al., 2002, Extracellular beta-D-glucosidase from Chaetomium thermophilum var. coprophilum: production, purification and some biochemical properties, J. Basic Microbiol. 42: 55-66. One unit of beta-glucosidase activity is defined as 1.0 μmole of p-nitrophenol produced per minute at 40° C., pH 5 from 1 mM p-nitrophenyl-beta-D-glucopyranoside as substrate in 100 mM sodium citrate containing 0.01% TWEEN® 20.
Isolated polypeptide: The term “isolated polypeptide” as used herein refers to a polypeptide that is isolated from a source. In a preferred aspect, the polypeptide is at least 1% pure, preferably at least 5% pure, more preferably at least 10% pure, more preferably at least 20% pure, more preferably at least 40% pure, more preferably at least 60% pure, even more preferably at least 80% pure, and most preferably at least 90% pure, as determined by SDS-PAGE.
Substantially pure polypeptide: The term “substantially pure polypeptide” denotes herein a polypeptide preparation that contains at most 10%, preferably at most 8%, more preferably at most 6%, more preferably at most 5%, more preferably at most 4%, more preferably at most 3%, even more preferably at most 2%, most preferably at most 1%, and even most preferably at most 0.5% by weight of other polypeptide material with which it is natively or recombinantly associated. It is, therefore, preferred that the substantially pure polypeptide is at least 92% pure, preferably at least 94% pure, more preferably at least 95% pure, more preferably at least 96% pure, more preferably at least 97% pure, more preferably at least 98% pure, even more preferably at least 99% pure, most preferably at least 99.5% pure, and even most preferably 100% pure by weight of the total polypeptide material present in the preparation. The polypeptides are preferably in a substantially pure form, i.e., that the polypeptide preparation is essentially free of other polypeptide material with which it is natively or recombinantly associated. This can be accomplished, for example, by preparing the polypeptide by well-known recombinant methods or by classical purification methods.
Mature polypeptide: The term “mature polypeptide” is defined herein as a polypeptide in its final form following translation and any post-translational modifications, such as N-terminal processing, C-terminal truncation, glycosylation, phosphorylation, etc.
Mature polypeptide coding sequence: The term “mature polypeptide coding sequence” is defined herein as a nucleotide sequence that encodes a mature polypeptide.
Identity: The relatedness between two amino acid sequences or between two nucleotide sequences is described by the parameter “identity”.
For purposes of the present invention, the degree of 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 in Genetics 16: 276-277), preferably version 3.0.0 or later. The optional parameters used are gap open penalty of 10, 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 degree of 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 3.0.0 or later. The optional parameters used are gap open penalty of 10, 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)

Homologous sequence: The term “homologous sequence” is defined herein as a predicted protein having an E value (or expectancy score) of less than 0.001 in a tfasty search (Pearson, W. R., 1999, in Bioinformatics Methods and Protocols, S. Misener and S. A. Krawetz, ed., pp. 185-219) with the polypeptides having cellulolytic enhancing activity of SEQ ID NOs: 2, 4, 6, 8, 10, 12, 14, or 16, or the mature polypeptides thereof.
Polypeptide fragment: The term “polypeptide fragment” is defined herein as a polypeptide having one or more (several) amino acids deleted from the amino and/or carboxyl terminus of a mature polypeptide or a homologous sequence thereof, wherein the fragment has cellulolytic enhancing activity.
Subsequence: The term “subsequence” is defined herein as a nucleotide sequence having one or more (several) nucleotides deleted from the 5′ and/or 3′ end of a mature polypeptide coding sequence or a homologous sequence thereof, wherein the subsequence encodes a polypeptide fragment having cellulolytic enhancing activity.
Allelic variant: The term “allelic variant” denotes herein 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.
Isolated polynucleotide: The term “isolated polynucleotide” as used herein refers to a polynucleotide that is isolated from a source. In a preferred aspect, the polynucleotide is at least 1% pure, preferably at least 5% pure, more preferably at least 10% pure, more preferably at least 20% pure, more preferably at least 40% pure, more preferably at least 60% pure, even more preferably at least 80% pure, and most preferably at least 90% pure, as determined by agarose electrophoresis.
Substantially pure polynucleotide: The term “substantially pure polynucleotide” as used herein refers to a polynucleotide preparation free of other extraneous or unwanted nucleotides and in a form suitable for use within genetically engineered protein production systems. Thus, a substantially pure polynucleotide contains at most 10%, preferably at most 8%, more preferably at most 6%, more preferably at most 5%, more preferably at most 4%, more preferably at most 3%, even more preferably at most 2%, most preferably at most 1%, and even most preferably at most 0.5% by weight of other polynucleotide material with which it is natively or recombinantly associated. A substantially pure polynucleotide may, however, include naturally occurring 5′ and 3′ untranslated regions, such as promoters and terminators. It is preferred that the substantially pure polynucleotide is at least 90% pure, preferably at least 92% pure, more preferably at least 94% pure, more preferably at least 95% pure, more preferably at least 96% pure, more preferably at least 97% pure, even more preferably at least 98% pure, most preferably at least 99% pure, and even most preferably at least 99.5% pure by weight. The polynucleotides are preferably in a substantially pure form, i.e., that the polynucleotide preparation is essentially free of other polynucleotide material with which it is natively or recombinantly associated. The polynucleotides may be of genomic, cDNA, RNA, semisynthetic, synthetic origin, or any combinations thereof.
Coding sequence: When used herein the term “coding sequence” means a nucleotide sequence, which directly specifies the amino acid sequence of its protein product. The boundaries of the coding sequence are generally determined by an open reading frame, which usually begins with the ATG start codon or alternative start codons such as GTG and TTG and ends with a stop codon such as TAA, TAG, and TGA. The coding sequence may be a DNA, cDNA, synthetic, or recombinant nucleotide sequence.
cDNA: The term “cDNA” is defined herein as a DNA molecule that can be prepared by reverse transcription from a mature, spliced, mRNA molecule obtained from a eukaryotic 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 before appearing as mature spliced mRNA. These steps include the removal of intron sequences by a process called splicing. cDNA derived from mRNA lacks, therefore, any intron sequences.
Nucleic acid construct: The term “nucleic acid construct” as used herein refers to a nucleic acid molecule, either single- or double-stranded, which is isolated from a naturally occurring gene or which is modified to contain segments of nucleic acids in a manner that would not otherwise exist in nature or which is synthetic. The term nucleic acid construct is synonymous with the term “expression cassette” when the nucleic acid construct contains the control sequences required for expression of a coding sequence.
Control sequences: The term “control sequences” is defined herein to include all components necessary for the expression of a polynucleotide encoding a polypeptide. Each control sequence may be native or foreign to the nucleotide sequence encoding the polypeptide 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 nucleotide sequence encoding a polypeptide.
Operably linked: The term “operably linked” denotes herein a configuration in which a control sequence is placed at an appropriate position relative to the coding sequence of the polynucleotide sequence such that the control sequence directs the expression of the coding sequence of a polypeptide.
Expression: The term “expression” includes any step involved in the production of a polypeptide including, but not limited to, transcription, post-transcriptional modification, translation, post-translational modification, and secretion.
Expression vector: The term “expression vector” is defined herein as a linear or circular DNA molecule that comprises a polynucleotide encoding a polypeptide and is operably linked to additional nucleotides that provide for its expression.
Host cell: The term “host cell”, as used herein, includes any cell type that is susceptible to transformation, transfection, transduction, and the like with a nucleic acid construct or expression vector comprising a polynucleotide of the present invention.
Artificial variant: When used herein, the term “artificial variant” means a modified polypeptide having cellulolytic enhancing activity produced by an organism expressing a modified polynucleotide sequence of the polypeptide having cellulolytic enhancing activity. The modified nucleotide sequence is obtained through human intervention by modification of the polynucleotide sequence. The term “modified” is understood herein to mean any chemical modification of a polypeptide having cellulolytic enhancing activity; as well as genetic manipulation of the DNA encoding such a polypeptide. The modification can be a substitution, a deletion, and/or an insertion of one or more (several) amino acids as well as replacements of one or more (several) amino acid side chains.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to methods for determining cellulolytic enhancing activity of a polypeptide, comprising: (a) incubating a cellulosic material with an enzyme composition comprising a cellobiose dehydrogenase and one or more (several) cellulolytic enzymes in the presence and absence of the polypeptide; and (b) measuring the release of sugar from the cellulosic material in the presence and absence of the polypeptide. In a preferred aspect, the polypeptide is a GH61 polypeptide.
There are several advantages associated with the methods of the present invention compared to methods currently in use. Highly homogenous, commercially available cellulose substrates with consistent and well-defined compositions can be used in place of pretreated biomass. High reproducibility of results are obtained due to the well-defined nature and consistent composition of such cellulose substrates. Recombinant purified enzymes can be employed in place of cellulase mixtures. Finally, the signal to noise ratio in the instant methods is significantly higher than that involving pretreated biomass and cellulase mixtures.
In the methods of the present invention, the polypeptide is incubated with the cellulosic material and the enzyme composition comprising the cellobiose dehydrogenase and the one or more (several) cellulolytic enzymes under conditions of pH and temperature that are optimal for the cellobiose dehydrogenase and/or the one or more cellulolytic enzymes.
The ratio of the polypeptide to the cellulosic material is preferably about 1 mg to about 50 mg per g of cellulose.
The ratio of the cellobiose dehydrogenase to the cellulosic material is preferably about 1 mg to about 10 mg per g of cellulose.
The ratio of the one or more cellulolytic enzymes to the cellulosic material is preferably about 5 mg to about 50 mg per g of cellulose.
Measuring the release of sugar from the cellulosic material can be accomplished using any method known in the art. Examples of such methods include, but are not limited to, measuring reducing sugars using the dinitrosalicyclic acid (DNS) method (Miller, 1959, Use of dinitrosalicylic acid reagent for determination of reducing sugar, Anal. Chem. 31: 426-428), the Nelson-Somogyi method (Nelson, 1944, A photometric adaptation of the Somogyi method for the determination of glucose, J. Biol. Chem. 153: 375-380; Somogyi, 1952, Notes on sugar determination, J. Biol. Chem. 195: 19-23), the 2,2-bicinchroninate (BCA) method (Waffenschmidt and Janeicke, 1987, Assay of reducing sugars in the nanomole range with 2,2-bicinchoninate, Anal. Biochem. 165: 337-340), the 4-hydroxybenzoylhydrazine (PAHBAH) method (Lever, 1972, A new reaction for colorimetric determination of carbohydratesnext term, Anal. Biochem. 47: 273-279), and the ferricyanide method (Kidby and Davidson, 1973, A convenient ferricyanide estimation of reducing sugars in the nanomole range, Anal. Biochem. 55: 321-325); measuring total soluble sugars by the phenol-sulfuric acid method (Dubois et al., 1956, Colormetric method for determination of sugars and relative substances, Anal. Chem. 28: 350-356) or the anthrone-sulfuric acid method (Viles and Silverman, 1949, Determination of starch and cellulose with anthrone, Anal. Chem. 21: 950-953); and measuring sugars by HPLC with refractive index detection using AMINEXTM HPX 87H columns (Bio-Rad Laboratories, Inc., Hercules, Calif., USA; Hodge et al., 2008, Soluble and insoluble solids contributions to high-solids enzymatic hydrolysis of lignocelluloses, Bioresource Technol. 99: 8940-8948).
The methods of the present invention can be combined with high-throughput, automated screening methods (Michael Lamsa, Nils Buchberg Jensen, and Steen Krogsgaard, Screen Automation and Robotiocs, in Enzyme Functionality: Design, Engineering, and Screening, A. Svendsen, editor, Marcel Dekker, 2003).
Cellulosic Material
The cellulosic material can be any material containing cellulose. The predominant polysaccharide in the primary cell wall of biomass is cellulose, the second most abundant is hemi-cellulose, 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, herbaceous material, agricultural residue, forestry residue, municipal solid waste, waste paper, and pulp and paper mill residue The cellulosic material can be any type of biomass including, but not limited to, wood resources, municipal solid waste, wastepaper, crops, and crop residues (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 the methods of the present invention, it is preferable to use highly homogenous, commercially available cellulose substrates with consistent and well-defined compositions to achieve highly reproducible results due to the well-defined nature and consistent composition of such cellulose substrates. In a preferred aspect, the cellulosic material is microcrystalline cellulose. In another preferred aspect, the cellulosic material is phosphoric acid swollen cellulose. In another preferred aspect, the cellulosic material is bacterial cellulose.
However, other cellulosic materials can also be used in the methods of the present invention.
In another aspect, the cellulosic material is herbaceous material. In another aspect, the cellulosic material is agricultural residue. In another aspect, the cellulosic material is forestry residue. In another aspect, the cellulosic material is municipal solid waste. In another aspect, the cellulosic material is waste paper. In another aspect, the cellulosic material is pulp and paper mill residue.
In another aspect, the cellulosic material is corn stover. In another preferred aspect, the cellulosic material is corn fiber. In another aspect, the cellulosic material is corn cob. In another aspect, the cellulosic material is orange peel. In another aspect, the cellulosic material is rice straw. In another aspect, the cellulosic material is wheat straw. In another aspect, the cellulosic material is switch grass. In another aspect, the cellulosic material is miscanthus. In another aspect, the cellulosic material is bagasse.
The cellulosic material may be used as is or may be subjected to pretreatment, using conventional methods known in the art. For example, physical pretreatment techniques can include various types of milling, irradiation, steaming/steam explosion, and hydrothermolysis; chemical pretreatment techniques can include dilute acid, alkaline, organic solvent, ammonia, sulfur dioxide, carbon dioxide, and pH-controlled hydrothermolysis; and biological pretreatment techniques can involve applying lignin-solubilizing microorganisms (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, P., and Singh, A., 1993, Physicochemical and biological treatments for enzymatic/microbial conversion of lignocellulosic biomass, 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, L., and Hahn-Hagerdal, B., 1996, Fermentation of lignocellulosic hydrolysates for ethanol production, Enz. Microb. Tech. 18: 312-331; and Vallander, L., and Eriksson, K.-E. L., 1990, Production of ethanol from lignocellulosic materials: State of the art, Adv. Biochem. Eng./Biotechnol. 42: 63-95).
Polypeptides Having Cellulolytic Enhancing Activity and Polynucleotides Thereof
In the methods of the present invention, the polypeptide can be any polypeptide. In one aspect, the polypeptide is a GH61 polypeptide.
In a first aspect, the GH61 polypeptide comprises the following motifs:
[ILMV]-P-X(4,5)-G-X-Y-[ILMV]-X-R-X-[EQ]-X(4)-[HNQ] and [FW]-[TF]-K-[AIV],
wherein X is any amino acid, X(4,5) is any amino acid at 4 or 5 contiguous positions, and X(4) is any amino acid at 4 contiguous positions.
The polypeptide comprising the above-noted motifs may further comprise:
H-X(1,2)-G-P-X(3)-[YW]-[AILMV],
[EQ]X-Y-X(2)-C-X-[EHQN]-[FILV]-X-[ILV], or
H-X(1,2)-G-P-X(3)-[YW]-[AILMV] and [EQ]X-Y-X(2)-C-X-[EHQN]-[FILV]-X-[ILV],
wherein X is any amino acid, X(1,2) is any amino acid at 1 position or 2 contiguous positions, X(3) is any amino acid at 3 contiguous positions, and X(2) is any amino acid at 2 contiguous positions. In the above motifs, the accepted IUPAC single letter amino acid abbreviation is employed.
In a preferred aspect, the GH61 polypeptide further comprises H-X(1,2)-G-P-X(3)-[YW]-[AILMV]. In another preferred aspect, the isolated polypeptide having cellulolytic enhancing activity further comprises [EQ]X-Y-X(2)-C-X-[EHQN]-[FILV]-X-[ILV]. In another preferred aspect, the GH61 polypeptide further comprises H-X(1,2)-G-P-X(3)-[YW]-[AILMV] and [EQ]-X-Y-X(2)-C-X-[EHQN]-[FILV]-X-[ILV].
In a second aspect, the GH61 polypeptide comprises the following motif:
[ILMV]P-x(4,5)-G-x-Y-[ILMV]-x-R-x-[EQ]-x(3)-A-[HNQ],
wherein x is any amino acid, x(4,5) is any amino acid at 4 or 5 contiguous positions, and x(3) is any amino acid at 3 contiguous positions. In the above motif, the accepted IUPAC single letter amino acid abbreviation is employed.
In a third aspect, the GH61 polypeptide comprises an amino acid sequence that has a degree of identity to the mature polypeptide of SEQ ID NO: 2, SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 14, or SEQ ID NO: 16 of preferably at least 60%, more preferably at least 65%, more preferably at least 70%, more preferably at least 75%, more preferably at least 80%, more preferably at least 85%, even more preferably at least 90%, most preferably at least 95%, and even most preferably at least 96%, at least 97%, at least 98%, or at least 99% (hereinafter “homologous polypeptides”). In a preferred aspect, the mature polypeptide sequence is amino acids 20 to 326 of SEQ ID NO: 2, amino acids 18 to 239 of SEQ ID NO: 4, amino acids 20 to 258 of SEQ ID NO: 6, amino acids 19 to 226 of SEQ ID NO: 8, amino acids 20 to 304 of SEQ ID NO: 10, amino acids 16 to 317 of SEQ ID NO: 12, amino acids 23 to 250 of SEQ ID NO: 14, or amino acids 20 to 249 of SEQ ID NO: 16.
In a fourth aspect, the GH61 polypeptide is encoded by a polynucleotide that hybridizes under at least very low stringency conditions, preferably at least low stringency conditions, more preferably at least medium stringency conditions, more preferably at least medium-high stringency conditions, even more preferably at least high stringency conditions, and most preferably at least very high stringency conditions with (i) the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 5, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, or SEQ ID NO: 15, (ii) the cDNA sequence contained in the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 5, or SEQ ID NO: 13, or the genomic DNA sequence comprising the mature polypeptide coding sequence of SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, or SEQ ID NO: 15, (iii) a subsequence of (i) or (ii), or (iv) a full-length complementary strand of (i), (ii), or (iii) (J. Sambrook, E. F. Fritsch, and T. Maniatus, 1989, supra). A subsequence of the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 5, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, or SEQ ID NO: 15 contains at least 100 contiguous nucleotides or preferably at least 200 contiguous nucleotides. In a preferred aspect, the mature polypeptide coding sequence is nucleotides 388 to 1332 of SEQ ID NO: 1, nucleotides 98 to 821 of SEQ ID NO: 3, nucleotides 126 to 978 of SEQ ID NO: 5, nucleotides 55 to 678 of SEQ ID NO: 7, nucleotides 58 to 912 of SEQ ID NO: 9, nucleotides 46 to 951 of SEQ ID NO: 11, nucleotides 67 to 796 of SEQ ID NO: 13, or nucleotides 77 to 766 of SEQ ID NO: 15.
The nucleotide sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 5, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, or SEQ ID NO: 15, or a subsequence thereof; as well as the amino acid sequence of SEQ ID NO: 2, SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 14, or SEQ ID NO: 16, or a fragment thereof, may be used to design a nucleic acid probe to identify and clone DNA encoding polypeptides having cellulolytic enhancing activity 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 or cDNA of the genus or species 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 14, preferably at least 25, more preferably at least 35, and most preferably at least 70 nucleotides in length. It is, however, preferred that the nucleic acid probe is at least 100 nucleotides in length. For example, the nucleic acid probe may be at least 200 nucleotides, preferably at least 300 nucleotides, more preferably at least 400 nucleotides, or most preferably at least 500 nucleotides in length. Even longer probes may be used, e.g., nucleic acid probes that are preferably at least 600 nucleotides, more preferably at least 700 nucleotides, even more preferably at least 800 nucleotides, or most preferably 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 32P, 3H, 35S, biotin, or avidin). Such probes are encompassed by the present invention.
A genomic DNA or cDNA library prepared from such other strains may, therefore, be screened for DNA that hybridizes with the probes described above. 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 is homologous with SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 5, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, or SEQ ID NO: 15, or a subsequence thereof, the carrier material is preferably used in a Southern blot.
For purposes of the present invention, hybridization indicates that the nucleotide sequence hybridizes to a labeled nucleic acid probe corresponding to the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 5, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, or SEQ ID NO: 13, the cDNA sequence contained in the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 5, or SEQ ID NO: 13, or the genomic DNA sequence comprising the mature polypeptide coding sequence of SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, or SEQ ID NO: 15, its full-length complementary strand, or a subsequence thereof, under very low to very high stringency conditions, as described supra.
In a preferred aspect, the nucleic acid probe is the mature polypeptide coding sequence of SEQ ID NO: 1. In another preferred aspect, the nucleic acid probe is nucleotides 388 to 1332 of SEQ ID NO: 1. In another preferred aspect, the nucleic acid probe is a polynucleotide sequence that encodes the polypeptide of SEQ ID NO: 2, or a subsequence thereof. In another preferred aspect, the nucleic acid probe is SEQ ID NO: 1. In another preferred aspect, the nucleic acid probe is the polynucleotide sequence contained in plasmid pEJG120 which is contained in E. coli NRRL B-30699, wherein the polynucleotide sequence thereof encodes a polypeptide having cellulolytic enhancing activity. In another preferred aspect, the nucleic acid probe is the mature polypeptide coding sequence contained in plasmid pEJG120 which is contained in E. coli NRRL B-30699.
In another preferred aspect, the nucleic acid probe is the mature polypeptide coding sequence of SEQ ID NO: 3. In another preferred aspect, the nucleic acid probe is nucleotides 98 to 821 of SEQ ID NO: 3. In another preferred aspect, the nucleic acid probe is a polynucleotide sequence that encodes the polypeptide of SEQ ID NO: 4, or a subsequence thereof. In another preferred aspect, the nucleic acid probe is SEQ ID NO: 3. In another preferred aspect, the nucleic acid probe is the polynucleotide sequence contained in plasmid pTter61C which is contained in E. coli NRRL B-30813, wherein the polynucleotide sequence thereof encodes a polypeptide having cellulolytic enhancing activity. In another preferred aspect, the nucleic acid probe is the mature polypeptide coding sequence contained in plasmid pTter61C which is contained in E. coli NRRL B-30813.
In another preferred aspect, the nucleic acid probe is the mature polypeptide coding sequence of SEQ ID NO: 5. In another preferred aspect, the nucleic acid probe is nucleotides 126 to 978 of SEQ ID NO: 5. In another preferred aspect, the nucleic acid probe is a polynucleotide sequence that encodes the polypeptide of SEQ ID NO: 6, or a subsequence thereof. In another preferred aspect, the nucleic acid probe is SEQ ID NO: 5. In another preferred aspect, the nucleic acid probe is the polynucleotide sequence contained in plasmid pTter61D which is contained in E. coli NRRL B-30812, wherein the polynucleotide sequence thereof encodes a polypeptide having cellulolytic enhancing activity. In another preferred aspect, the nucleic acid probe is the mature polypeptide coding sequence contained in plasmid pTter61D which is contained in E. coli NRRL B-30812.
In another preferred aspect, the nucleic acid probe is the mature polypeptide coding sequence of SEQ ID NO: 7. In another preferred aspect, the nucleic acid probe is nucleotides 55 to 678 of SEQ ID NO: 7. In another preferred aspect, the nucleic acid probe is a polynucleotide sequence that encodes the polypeptide of SEQ ID NO: 8, or a subsequence thereof. In another preferred aspect, the nucleic acid probe is SEQ ID NO: 7. In another preferred aspect, the nucleic acid probe is the polynucleotide sequence contained in plasmid pTter61E which is contained in E. coli NRRL B-30814, wherein the polynucleotide sequence thereof encodes a polypeptide having cellulolytic enhancing activity. In another preferred aspect, the nucleic acid probe is the mature polypeptide coding sequence contained in plasmid pTter61E which is contained in E. coli NRRL B-30814.
In another preferred aspect, the nucleic acid probe is the mature polypeptide coding sequence of SEQ ID NO: 9. In another preferred aspect, the nucleic acid probe is nucleotides 58 to 912 of SEQ ID NO: 9 In another preferred aspect, the nucleic acid probe is a polynucleotide sequence that encodes the polypeptide of SEQ ID NO: 10, or a subsequence thereof. In another preferred aspect, the nucleic acid probe is SEQ ID NO: 9. In another preferred aspect, the nucleic acid probe is the polynucleotide sequence contained in plasmid pTter61G which is contained in E. coli NRRL B-30811, wherein the polynucleotide sequence thereof encodes a polypeptide having cellulolytic enhancing activity. In another preferred aspect, the nucleic acid probe is the mature polypeptide coding sequence contained in plasmid pTter61G which is contained in E. coli NRRL B-30811.
In another preferred aspect, the nucleic acid probe is the mature polypeptide coding sequence of SEQ ID NO: 11. In another preferred aspect, the nucleic acid probe is nucleotides 46 to 951 of SEQ ID NO: 11. In another preferred aspect, the nucleic acid probe is a polynucleotide sequence that encodes the polypeptide of SEQ ID NO: 12, or a subsequence thereof. In another preferred aspect, the nucleic acid probe is SEQ ID NO: 11. In another preferred aspect, the nucleic acid probe is the polynucleotide sequence contained in plasmid pTter61F which is contained in E. coli NRRL B-50044, wherein the polynucleotide sequence thereof encodes a polypeptide having cellulolytic enhancing activity. In another preferred aspect, the nucleic acid probe is the mature polypeptide coding region contained in plasmid pTter61F which is contained in E. coli NRRL B-50044.
In another preferred aspect, the nucleic acid probe is the mature polypeptide coding sequence of SEQ ID NO: 13. In another preferred aspect, the nucleic acid probe is nucleotides 67 to 796 of SEQ ID NO: 13. In another preferred aspect, the nucleic acid probe is a polynucleotide sequence that encodes the polypeptide of SEQ ID NO: 14, or a subsequence thereof. In another preferred aspect, the nucleic acid probe is SEQ ID NO: 13. In another preferred aspect, the nucleic acid probe is the polynucleotide sequence contained in plasmid pDZA2-7 which is contained in E. coli NRRL B-30704, wherein the polynucleotide sequence thereof encodes a polypeptide having cellulolytic enhancing activity. In another preferred aspect, the nucleic acid probe is the mature polypeptide coding sequence contained in plasmid pDZA2-7 which is contained in E. coli NRRL B-30704.
In another preferred aspect, the nucleic acid probe is the mature polypeptide coding sequence of SEQ ID NO: 15. In another preferred aspect, the nucleic acid probe is nucleotides 77 to 766 of SEQ ID NO: 15. In another preferred aspect, the nucleic acid probe is a polynucleotide sequence that encodes the polypeptide of SEQ ID NO: 16, or a subsequence thereof. In another preferred aspect, the nucleic acid probe is SEQ ID NO: 15. In another preferred aspect, the nucleic acid probe is the polynucleotide sequence contained in plasmid pTr333 which is contained in E. coli NRRL B-30878, wherein the polynucleotide sequence thereof encodes a polypeptide having cellulolytic enhancing activity. In another preferred aspect, the nucleic acid probe is the mature polypeptide coding sequence contained in plasmid pTr333 which is contained in E. coli NRRL B-30878.
For long probes of at least 100 nucleotides in length, very low to very high stringency conditions are defined as prehybridization and hybridization at 42° C. in 5×SSPE, 0.3% SDS, 200 μg/ml sheared and denatured salmon sperm DNA, and either 25% formamide for very low and low stringencies, 35% formamide for medium and medium-high stringencies, or 50% formamide for high and very high stringencies, following standard Southern blotting procedures for 12 to 24 hours optimally.
For long probes of at least 100 nucleotides in length, the carrier material is finally washed three times each for 15 minutes using 2×SSC, 0.2% SDS preferably at 45° C. (very low stringency), more preferably at 50° C. (low stringency), more preferably at 55° C. (medium stringency), more preferably at 60° C. (medium-high stringency), even more preferably at 65° C. (high stringency), and most preferably at 70° C. (very high stringency).
For short probes of about 15 nucleotides to about 70 nucleotides in length, stringency conditions are defined as prehybridization, hybridization, and washing post-hybridization at about 5° C. to about 10° C. below the calculated Tn, using the calculation according to Bolton and McCarthy (1962, Proceedings of the National Academy of Sciences USA 48:1390) in 0.9 M NaCl, 0.09 M Tris-HCl pH 7.6, 6 mM EDTA, 0.5% NP-40, 1×Denhardt's solution, 1 mM sodium pyrophosphate, 1 mM sodium monobasic phosphate, 0.1 mM ATP, and 0.2 mg of yeast RNA per ml following standard Southern blotting procedures for 12 to 24 hours optimally.
For short probes of about 15 nucleotides to about 70 nucleotides in length, the carrier material is washed once in 6×SCC plus 0.1% SDS for 15 minutes and twice each for 15 minutes using 6×SSC at 5° C. to 10° C. below the calculated Tm.
In a fifth aspect, the GH61 polypeptide is encoded by a polynucleotide comprising or consisting of a nucleotide sequence that has a degree of identity to the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 5, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, or SEQ ID NO: 15 of preferably at least 60%, more preferably at least 65%, more preferably at least 70%, more preferably at least 75%, more preferably at least 80%, more preferably at least 85%, even more preferably at least 90%, most preferably at least 95%, and even most preferably at least 96%, at least 97%, at least 98%, or at least 99%.
In a preferred aspect, the mature polypeptide coding sequence is nucleotides 388 to 1332 of SEQ ID NO: 1, nucleotides 98 to 821 of SEQ ID NO: 3, nucleotides 126 to 978 of SEQ ID NO: 5, nucleotides 55 to 678 of SEQ ID NO: 7, nucleotides 58 to 912 of SEQ ID NO: 9, nucleotides 46 to 951 of SEQ ID NO: 11, nucleotides 67 to 796 of SEQ ID NO: 13, or nucleotides 77 to 766 of SEQ ID NO: 15.
In a sixth aspect, the GH61 polypeptide is an artificial variant comprising a substitution, deletion, and/or insertion of one or more (or several) amino acids of a parent polypeptide.
A GH61 polypeptide may be obtained from microorganisms of any genus. In a preferred aspect, the polypeptide obtained from a given source is secreted extracellularly.
A GH61 polypeptide 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, or Oceanobacillus GH61 polypeptide, or a Gram negative bacterial polypeptide such as an E. coli, Pseudomonas, Salmonella, Campylobacter, Helicobacter, Flavobacterium, Fusobacterium, Ilyobacter, Neisseria, or Ureaplasma GH61 polypeptide.
In a preferred 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 GH61 polypeptide.
In another preferred aspect, the polypeptide is a Streptococcus equisimilis, Streptococcus pyogenes, Streptococcus uberis, or Streptococcus equi subsp. Zooepidemicus GH61 polypeptide.
In another preferred aspect, the polypeptide is a Streptomyces achromogenes, Streptomyces avermitilis, Streptomyces coelicolor, Streptomyces griseus, or Streptomyces lividans GH61 polypeptide.
The GH61 polypeptide may also be a fungal polypeptide, and more preferably a yeast polypeptide such as a Candida, Kluyveromyces, Pichia, Saccharomyces, Schizosaccharomyces, or Yarrowia GH61 polypeptide; or more preferably a filamentous fungal polypeptide such as an Acremonium, Agaricus, Alternaria, Aspergillus, Aureobasidium, Botryospaeria, 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 GH61 polypeptide.
In a preferred aspect, the polypeptide is a Saccharomyces carlsbergensis, Saccharomyces cerevisiae, Saccharomyces diastaticus, Saccharomyces douglasii, Saccharomyces kluyveri, Saccharomyces norbensis, or Saccharomyces oviformis GH61 polypeptide.
In another preferred 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 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 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 harzianum, Trichoderma koningii, Trichoderma longibrachiatum, Trichoderma reesei, Trichoderma viride, or Trichophaea saccata GH61 polypeptide.
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 (DSM), Centraalbureau Voor Schimmelcultures (CBS), and Agricultural Research Service Patent Culture Collection, Northern Regional Research Center (NRRL).
Furthermore, GH61 polypeptides may be identified and obtained from other sources including microorganisms isolated from nature (e.g., soil, composts, water, etc.) using the above-mentioned probes. Techniques for isolating microorganisms from natural habitats are well known in the art. The polynucleotide may then be obtained by similarly screening a genomic or cDNA library of such a microorganism. Once a polynucleotide encoding a polypeptide has been detected with the probe(s), the polynucleotide can be isolated or cloned by utilizing techniques that are well known to those of ordinary skill in the art (see, e.g., Sambrook et al., 1989, supra)
Polynucleotides comprising nucleotide sequences that encode GH61 polypeptides can be isolated and utilized to express the GH61 polypeptides for evaluation in the methods of the present invention, as described herein.
The polynucleotides comprise nucleotide sequences that have a degree of identity to the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 5, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, or SEQ ID NO: 15 of preferably at least 60%, more preferably at least 65%, more preferably at least 70%, more preferably at least 75%, more preferably at least 80%, more preferably at least 85%, even more preferably at least 90%, most preferably at least 95%, and even most preferably at least 96%, at least 97%, at least 98%, or at least 99%, which encode a polypeptide having cellulolytic enhancing activity.
The polynucleotide may also be a polynucleotide encoding a GH61 polypeptide that hybridizes under at least very low stringency conditions, preferably at least low stringency conditions, more preferably at least medium stringency conditions, more preferably at least medium-high stringency conditions, even more preferably at least high stringency conditions, and most preferably at least very high stringency conditions with (i) the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 5, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, or SEQ ID NO: 15, (ii) the cDNA sequence contained in the mature polypeptide coding sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 5, or SEQ ID NO: 13, or the genomic DNA sequence comprising the mature polypeptide coding sequence of SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, or SEQ ID NO: 15, or (iii) a full-length complementary strand of (i) or (ii); or allelic variants and subsequences thereof (Sambrook et al., 1989, supra), as defined herein. In a preferred aspect, the mature polypeptide coding sequence is nucleotides 388 to 1332 of SEQ ID NO: 1, nucleotides 98 to 821 of SEQ ID NO: 3, nucleotides 126 to 978 of SEQ ID NO: 5, nucleotides 55 to 678 of SEQ ID NO: 7, nucleotides 58 to 912 of SEQ ID NO: 9, nucleotides 46 to 951 of SEQ ID NO: 11, nucleotides 67 to 796 of SEQ ID NO: 13, or nucleotides 77 to 766 of SEQ ID NO: 15.
As described earlier, the techniques used to isolate or clone a polynucleotide encoding a polypeptide are known in the art and include isolation from genomic DNA, preparation from cDNA, or a combination thereof.
In practicing the methods of the present invention, several polypeptides having cellulolytic enhancing activity, as described below, can be used as standards in determining whether a polypeptide has cellulolytic enhancing activity.
A polypeptide having cellulolytic enhancing activity preferably comprises the amino acid sequence of SEQ ID NO: 2 or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In a preferred aspect, the polypeptide comprises the amino acid sequence of SEQ ID NO: 2. In another preferred aspect, the polypeptide comprises the mature polypeptide of SEQ ID NO: 2. In another preferred aspect, the polypeptide comprises amino acids 20 to 326 of SEQ ID NO: 2, or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In another preferred aspect, the polypeptide comprises amino acids 20 to 326 of SEQ ID NO: 2. In another preferred aspect, the polypeptide consists of the amino acid sequence of SEQ ID NO: 2 or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In another preferred aspect, the polypeptide consists of the amino acid sequence of SEQ ID NO: 2. In another preferred aspect, the polypeptide consists of the mature polypeptide of SEQ ID NO: 2. In another preferred aspect, the polypeptide consists of amino acids 20 to 326 of SEQ ID NO: 2 or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In another preferred aspect, the polypeptide consists of amino acids 20 to 326 of SEQ ID NO: 2.
A polypeptide having cellulolytic enhancing activity preferably comprises the amino acid sequence of SEQ ID NO: 4 or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In a preferred aspect, the polypeptide comprises the amino acid sequence of SEQ ID NO: 4. In another preferred aspect, the polypeptide comprises the mature polypeptide of SEQ ID NO: 4. In another preferred aspect, the polypeptide comprises amino acids 18 to 239 of SEQ ID NO: 4, or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In another preferred aspect, the polypeptide comprises amino acids 18 to 239 of SEQ ID NO: 4. In another preferred aspect, the polypeptide consists of the amino acid sequence of SEQ ID NO: 4 or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In another preferred aspect, the polypeptide consists of the amino acid sequence of SEQ ID NO: 4. In another preferred aspect, the polypeptide consists of the mature polypeptide of SEQ ID NO: 4. In another preferred aspect, the polypeptide consists of amino acids 18 to 239 of SEQ ID NO: 4 or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In another preferred aspect, the polypeptide consists of amino acids 18 to 239 of SEQ ID NO: 4.
A polypeptide having cellulolytic enhancing activity preferably comprises the amino acid sequence of SEQ ID NO: 6 or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In a preferred aspect, the polypeptide comprises the amino acid sequence of SEQ ID NO: 6. In another preferred aspect, the polypeptide comprises the mature polypeptide of SEQ ID NO: 6. In another preferred aspect, the polypeptide comprises amino acids 20 to 258 of SEQ ID NO: 6, or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In another preferred aspect, the polypeptide comprises amino acids 20 to 258 of SEQ ID NO: 6. In another preferred aspect, the polypeptide consists of the amino acid sequence of SEQ ID NO: 6 or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In another preferred aspect, the polypeptide consists of the amino acid sequence of SEQ ID NO: 6. In another preferred aspect, the polypeptide consists of the mature polypeptide of SEQ ID NO: 6. In another preferred aspect, the polypeptide consists of amino acids 20 to 258 of SEQ ID NO: 6 or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In another preferred aspect, the polypeptide consists of amino acids 20 to 258 of SEQ ID NO: 6.
A polypeptide having cellulolytic enhancing activity preferably comprises the amino acid sequence of SEQ ID NO: 8 or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In a preferred aspect, the polypeptide comprises the amino acid sequence of SEQ ID NO: 8. In another preferred aspect, the polypeptide comprises the mature polypeptide of SEQ ID NO: 8. In another preferred aspect, the polypeptide comprises amino acids 19 to 226 of SEQ ID NO: 8, or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In another preferred aspect, the polypeptide comprises amino acids 19 to 226 of SEQ ID NO: 8. In another preferred aspect, the polypeptide consists of the amino acid sequence of SEQ ID NO: 8 or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In another preferred aspect, the polypeptide consists of the amino acid sequence of SEQ ID NO: 8. In another preferred aspect, the polypeptide consists of the mature polypeptide of SEQ ID NO: 8. In another preferred aspect, the polypeptide consists of amino acids 19 to 226 of SEQ ID NO: 8 or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In another preferred aspect, the polypeptide consists of amino acids 19 to 226 of SEQ ID NO: 8.
A polypeptide having cellulolytic enhancing activity preferably comprises the amino acid sequence of SEQ ID NO: 10 or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In a preferred aspect, the polypeptide comprises the amino acid sequence of SEQ ID NO: 10. In another preferred aspect, the polypeptide comprises the mature polypeptide of SEQ ID NO: 10. In another preferred aspect, the polypeptide comprises amino acids 20 to 304 of SEQ ID NO: 10, or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In another preferred aspect, the polypeptide comprises amino acids 20 to 304 of SEQ ID NO: 10. In another preferred aspect, the polypeptide consists of the amino acid sequence of SEQ ID NO: 10 or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In another preferred aspect, the polypeptide consists of the amino acid sequence of SEQ ID NO: 10. In another preferred aspect, the polypeptide consists of the mature polypeptide of SEQ ID NO: 10. In another preferred aspect, the polypeptide consists of amino acids 20 to 304 of SEQ ID NO: 10 or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In another preferred aspect, the polypeptide consists of amino acids 20 to 304 of SEQ ID NO: 10.
A polypeptide having cellulolytic enhancing activity preferably comprises the amino acid sequence of SEQ ID NO: 12 or an allelic variant thereof; or a fragment thereof having cellulolytic enhancing activity. In a preferred aspect, the polypeptide comprises the amino acid sequence of SEQ ID NO: 12. In another preferred aspect, the polypeptide comprises the mature polypeptide of SEQ ID NO: 12. In another preferred aspect, the polypeptide comprises amino acids 16 to 317 of SEQ ID NO: 12, or an allelic variant thereof; or a fragment thereof having cellulolytic enhancing activity. In another preferred aspect, the polypeptide comprises amino acids 16 to 317 of SEQ ID NO: 12. In another preferred aspect, the polypeptide consists of the amino acid sequence of SEQ ID NO: 12 or an allelic variant thereof; or a fragment thereof having cellulolytic enhancing activity. In another preferred aspect, the polypeptide consists of the amino acid sequence of SEQ ID NO: 12. In another preferred aspect, the polypeptide consists of the mature polypeptide of SEQ ID NO: 12. In another preferred aspect, the polypeptide consists of amino acids 16 to 317 of SEQ ID NO: 12 or an allelic variant thereof; or a fragment thereof having cellulolytic enhancing activity. In another preferred aspect, the polypeptide consists of amino acids 16 to 317 of SEQ ID NO: 12.
A polypeptide having cellulolytic enhancing activity preferably comprises the amino acid sequence of SEQ ID NO: 14 or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In a preferred aspect, the polypeptide comprises the amino acid sequence of SEQ ID NO: 14. In another preferred aspect, the polypeptide comprises the mature polypeptide of SEQ ID NO: 14. In another preferred aspect, the polypeptide comprises amino acids 23 to 250 of SEQ ID NO: 14, or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In another preferred aspect, the polypeptide comprises amino acids 23 to 250 of SEQ ID NO: 14. In another preferred aspect, the polypeptide consists of the amino acid sequence of SEQ ID NO: 14 or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In another preferred aspect, the polypeptide consists of the amino acid sequence of SEQ ID NO: 14. In another preferred aspect, the polypeptide consists of the mature polypeptide of SEQ ID NO: 14. In another preferred aspect, the polypeptide consists of amino acids 23 to 250 of SEQ ID NO: 14 or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In another preferred aspect, the polypeptide consists of amino acids 23 to 250 of SEQ ID NO: 14.
A polypeptide having cellulolytic enhancing activity preferably comprises the amino acid sequence of SEQ ID NO: 16 or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In a preferred aspect, the polypeptide comprises the amino acid sequence of SEQ ID NO: 16. In another preferred aspect, the polypeptide comprises the mature polypeptide of SEQ ID NO: 16. In another preferred aspect, the polypeptide comprises amino acids 20 to 249 of SEQ ID NO: 16, or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In another preferred aspect, the polypeptide comprises amino acids 20 to 249 of SEQ ID NO: 16. In another preferred aspect, the polypeptide consists of the amino acid sequence of SEQ ID NO: 16 or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In another preferred aspect, the polypeptide consists of the amino acid sequence of SEQ ID NO: 16. In another preferred aspect, the polypeptide consists of the mature polypeptide of SEQ ID NO: 16. In another preferred aspect, the polypeptide consists of amino acids 20 to 249 of SEQ ID NO: 16 or an allelic variant thereof; or a fragment thereof that has cellulolytic enhancing activity. In another preferred aspect, the polypeptide consists of amino acids 20 to 249 of SEQ ID NO: 16.
Preferably, a fragment of the mature polypeptide of SEQ ID NO: 2 contains at least 277 amino acid residues, more preferably at least 287 amino acid residues, and most preferably at least 297 amino acid residues. Preferably, a fragment of the mature polypeptide of SEQ ID NO: 4 contains at least 185 amino acid residues, more preferably at least 195 amino acid residues, and most preferably at least 205 amino acid residues. Preferably, a fragment of the mature polypeptide of SEQ ID NO: 6 contains at least 200 amino acid residues, more preferably at least 212 amino acid residues, and most preferably at least 224 amino acid residues. Preferably, a fragment of the mature polypeptide of SEQ ID NO: 8 contains at least 175 amino acid residues, more preferably at least 185 amino acid residues, and most preferably at least 195 amino acid residues. Preferably, a fragment of the mature polypeptide of SEQ ID NO: 10 contains at least 240 amino acid residues, more preferably at least 255 amino acid residues, and most preferably at least 270 amino acid residues. Preferably, a fragment of the mature polypeptide of SEQ ID NO: 12 contains at least 255 amino acid residues, more preferably at least 270 amino acid residues, and most preferably at least 285 amino acid residues. Preferably, a fragment of the mature polypeptide of SEQ ID NO: 14 contains at least 175 amino acid residues, more preferably at least 190 amino acid residues, and most preferably at least 205 amino acid residues. Preferably, a fragment of the mature polypeptide of SEQ ID NO: 16 contains at least 200 amino acid residues, more preferably at least 210 amino acid residues, and most preferably at least 220 amino acid residues.
Preferably, a subsequence of the mature polypeptide coding sequence of SEQ ID NO: 1 contains at least 831 nucleotides, more preferably at least 861 nucleotides, and most preferably at least 891 nucleotides. Preferably, a subsequence of the mature polypeptide coding sequence of SEQ ID NO: 3 contains at least 555 nucleotides, more preferably at least 585 nucleotides, and most preferably at least 615 nucleotides. Preferably, a subsequence of the mature polypeptide coding sequence of SEQ ID NO: 5 contains at least 600 nucleotides, more preferably at least 636 nucleotides, and most preferably at least 672 nucleotides. Preferably, a subsequence of the mature polypeptide coding sequence of SEQ ID NO: 7 contains at least 525 nucleotides, more preferably at least 555 nucleotides, and most preferably at least 585 nucleotides. Preferably, a subsequence of the mature polypeptide coding sequence of SEQ ID NO: 9 contains at least 720 nucleotides, more preferably at least 765 nucleotides, and most preferably at least 810 nucleotides. Preferably, a subsequence of the mature polypeptide coding sequence of SEQ ID NO: 11 contains at least 765 nucleotides, more preferably at least 810 nucleotides, and most preferably at least 855 nucleotides Preferably, a subsequence of the mature polypeptide coding sequence of nucleotides 67 to 796 of SEQ ID NO: 13 contains at least 525 nucleotides, more preferably at least 570 nucleotides, and most preferably at least 615 nucleotides. Preferably, a subsequence of the mature polypeptide coding sequence of SEQ ID NO: 15 contains at least 600 nucleotides, more preferably at least 630 nucleotides, and most preferably at least 660 nucleotides.
Cellobiose Dehydrogenases and Polynucleotides Thereof
In the methods of the present invention, the cellobiose dehydrogenase can be any cellobiose dehydrogenase.
A cellobiose dehydrogenase 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 polypeptide encoded by a nucleotide sequence is produced by the source or by a strain in which the nucleotide sequence from the source has been inserted. In a preferred aspect, the polypeptide obtained from a given source is secreted extracellularly.
A cellobiose dehydrogenase 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, or Oceanobacillus cellobiose dehydrogenase, or a Gram negative bacterial polypeptide such as an E. coli, Pseudomonas, Salmonella, Campylobacter, Helicobacter, Flavobacterium, Fusobacterium, Ilyobacter, Neisseria, or Ureaplasma cellobiose dehydrogenase.
In a preferred 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 cellobiose dehydrogenase.
In another preferred aspect, the polypeptide is a Streptococcus equisimilis, Streptococcus pyogenes, Streptococcus uberis, or Streptococcus equi subsp. Zooepidemicus cellobiose dehydrogenase.
In another preferred aspect, the polypeptide is a Streptomyces achromogenes, Streptomyces avermitilis, Streptomyces coelicolor, Streptomyces griseus, or Streptomyces lividans cellobiose dehydrogenase.
A cellobiose dehydrogenase may also be a fungal polypeptide, and more preferably a yeast polypeptide such as a Candida, Kluyveromyces, Pichia, Saccharomyces, Schizosaccharomyces, or Yarrowia cellobiose dehydrogenase; or more preferably a filamentous fungal polypeptide such as an Acremonium, Agaricus, Alternaria, Aspergillus, Aureobasidium, Botryospaeria, 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 cellobiose dehydrogenase.
In a preferred aspect, the polypeptide is a Saccharomyces carlsbergensis, Saccharomyces cerevisiae, Saccharomyces diastaticus, Saccharomyces douglasii, Saccharomyces kluyveri, Saccharomyces norbensis, or Saccharomyces oviformis cellobiose dehydrogenase.
In another preferred 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 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 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 harzianum, Trichoderma koningii, Trichoderma longibrachiatum, Trichoderma reesei, or Trichoderma viride cellobiose dehydrogenase.
Examples of other cellobiose dehydrogenases useful in the present invention are listed in Table 1.







TABLE 1







Published microbial cellobiose dehydrogenase sequences









Species
Accession #
Literature Reference





Humicola
Q9P8H5
Xu et al., 2001, Humicola insolens cellobiose


insolens

dehydrogenase: cloning, redox chemistry, and




“logic gate”-like dual functionality, Enz. Microb.




Technol. 28: 744-753


Irpex lacteus
Q6AW20
Nozaki et al., 1999, Cloning and expression of




cellobiose dehydrogenase from Irpex lacteus.




Submitted (AUGUST 2004) to the




EMBL/GenBank/DDBJ databases.


Pycnoporus
O74253
Moukha et al., 1999, Cloning and analysis of


cinnabarinus

Pycnoporus cinnabarinus cellobiose




dehydrogenase, Gene 234: 23-33


Phanerochaete
Q01738
Li et al., 1996, Cloning of a cDNA encoding


chrysosporium

cellobiose dehydrogenase, a hemoflavoenzyme




from Phanerochaete chrysosporium, Appl.




Environ. Microbiol. 62: 1329-1335


Coniophora
Q6BDD5
Kajisa et al., 2004, Characterization and


puteana

molecular cloning of cellobiose dehydrogenase




from the brown-rot fungus Coniophora puteana,




Biosci. Bioeng. 98: 57-63


Athelia rolfsii
Q7Z975
Zamocky et al., Phylogenetic analysis of




cellobiose dehydrogenases. Submitted (NOVEMBER




2002) to the EMBL/GenBank/DDBJ databases


Grifola
Q8J2T4
Yoshida et al., 2002, Molecular cloning and


frondosa

characterization of a cDNA encoding cellobiose




dehydrogenase from the wood-rotting fungus




Grifola frondosa, FEMS Microbiol. Lett. 217:




225-230


Trametes
Q875J3
Stapleton et al., 2004, Molecular cloning of the


versicolor

cellobiose dehydrogenase gene from Trametes




versicolor and expression in Pichia pastoris,




Enzyme Microb. Technol. 34: 55-63


Trametes
O42729
Dumonceaux et al., 1998, Cloning and


versicolor

sequencing of a gene encoding cellobiose




dehydrogenase from Trametes versicolor, Gene




210: 211-219


Aspergillus
Q4WIN9
Nierman et al., 2005, Genomic sequence of the


fumigatus

pathogenic and allergenic filamentous fungus




Aspergillus fumigatus, Nature 438: 1151-1156


Phanerochaete
Q12661
Raices et al., 1995, Cloning and


chrysosporium

characterization of a cDNA encoding a




cellobiose dehydrogenase from the white rot




fungus Phanerochaete chrysosporium, FEBS




Lett. 369: 233-238


Myriococcum
A9XK88
Zamocky et al., 2008, Cloning, sequence


thermophilum

analysis and heterologous expression in Pichia




pastoris of a gene encoding a thermostable




cellobiose dehydrogenase from Myriococcum




thermophilum, Protein Expr. Purif. 59: 258-265


Aspergillus
A1CFVO
Fedorova et al., Genomic islands in the


clavatus

pathogenic filamentous fungus Aspergillus




fumigatus, PLoS


Corynascus
O74240
Subramaniam et al., Biochemical and molecular


heterothallicus

biological characterization of cellobiose




dehydrogenase from Sporotrichum thermophile.




Submitted (JUNE 1998) to the




EMBL/GenBank/DDBJ databases


Neosartorya
A1CYG2
Fedorova et al., Genomic islands in the


fischeri

pathogenic filamentous fungus Aspergillus




fumigatus, PLoS


Aspergillus
B0XVQ8
Fedorova et al., Genomic islands in the


fumigatus

pathogenic filamentous fungus Aspergillus




fumigatus, PLoS


Aspergillus
A1C890
Fedorova et al., Genomic islands in the


clavatus

pathogenic filamentous fungus Aspergillus




fumigatus, PLoS


Neosartorya
A1DIY3
Fedorova et al., Genomic islands in the


fischeri

pathogenic filamentous fungus Aspergillus




fumigatus, PLoS


Myriococcum
A9XK87
Zamocky et al., 2008, Cloning, sequence


thermophilum

analysis and heterologous expression in Pichia




pastoris of a gene encoding a thermostable




cellobiose dehydrogenase from Myriococcum




thermophilum, Protein Expr. Purif. 59: 258-265


Pyrenophora
B2WHI7
Birren et al., The Broad Institute Genome


tritici-repentis

Sequencing Platform “Genome Sequence of




Pyrenophora tritici-repentis. Submitted (MARCH




2007) to the EMBL/GenBank/DDBJ databases


Pyrenophora
B2WJX3
Birren et al., The Broad Institute Genome


tritici-repentis

Sequencing Platform “Genome Sequence of




Pyrenophora tritici-repentis. Submitted (MARCH




2007) to the EMBL/GenBank/DDBJ databases


Aspergillus
Q4WC40
Fedorova et al., Genomic islands in the


fumigatus

pathogenic filamentous fungus Aspergillus




fumigatus, PLoS


Aspergillus
A2QD75
Pel et al., 2007, Genome sequencing and


niger

analysis of the versatile cell factory Aspergillus




niger CBS 513.88, Nat. Biotechnol. 25: 221-231









In a more preferred aspect, the cellobiose dehydrogenase is a Humicola insolens cellobiose dehydrogenase. In a most preferred aspect, the cellobiose dehydrogenase is a Humicola insolens DSM 1800 cellobiose dehydrogenase, e.g., the polypeptide comprising SEQ ID NO: 18 encoded by SEQ ID NO: 17, or a fragment thereof having cellobiose dehydrogenase activity (see U.S. Pat. No. 6,280,976).
In another more preferred aspect, the cellobiose dehydrogenase is a Myceliophthora thermophila cellobiose dehydrogenase. In a most preferred aspect, the cellobiose dehydrogenase is a Myceliophthora thermophila CBS117.65 cellobiose dehydrogenase.
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 (DSM), Centraalbureau Voor Schimmelcultures (CBS), and Agricultural Research Service Patent Culture Collection, Northern Regional Research Center (NRRL).
Cellulolytic Enzymes
In the methods of the present invention, the one or more (several) cellulolytic enzymes can be any cellulolytic enzyme involved in the processing of a cellulosic material, e.g., lignocellulose, to fermentable sugars, e.g., glucose. For cellulose degradation, at least three categories of enzymes are important for converting cellulose into fermentable sugars: endoglucanases (E.C. 3.2.1.4) that hydrolyze the cellulose chains at random; cellobiohydrolases (E.C. 3.2.1.91) that cleave cellobiosyl units from the cellulose chain ends, and beta-glucosidases (E.C. 3.2.1.21) that convert cellobiose and soluble cellodextrins into glucose.
A polypeptide having cellulolytic 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, or Oceanobacillus polypeptide having cellulolytic 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 cellulolytic enzyme activity.
In a preferred 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 cellulolytic enzyme activity.
In another preferred aspect, the polypeptide is a Streptococcus equisimilis, Streptococcus pyogenes, Streptococcus uberis, or Streptococcus equi subsp. Zooepidemicus polypeptide having cellulolytic enzyme activity.
In another preferred aspect, the polypeptide is a Streptomyces achromogenes, Streptomyces avermitilis, Streptomyces coelicolor, Streptomyces griseus, or Streptomyces lividans polypeptide having cellulolytic enzyme activity.
The polypeptide having cellulolytic 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 cellulolytic enzyme activity; or more preferably a filamentous fungal polypeptide such as an Acremonium, Agaricus, Alternaria, Aspergillus, Aureobasidium, Botryospaeria, 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 cellulolytic enzyme activity.
In a preferred aspect, the polypeptide is a Saccharomyces carlsbergensis, Saccharomyces cerevisiae, Saccharomyces diastaticus, Saccharomyces douglasii, Saccharomyces kluyveri, Saccharomyces norbensis, or Saccharomyces oviformis polypeptide having cellulolytic enzyme activity.
In another preferred 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 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 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 harzianum, Trichoderma koningii, Trichoderma longibrachiatum, Trichoderma reesei, Trichoderma viride, or Trichophaea saccata polypeptide having cellulolytic enzyme activity.
Chemically modified or protein engineered mutants of cellulolytic enzymes may also be used.
The one or more (several) cellulolytic enzymes may be a recombinant enzyme, i.e., produced by cloning of a DNA sequence encoding the single enzyme 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 is preferably 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.
The one or more (several) cellulolytic enzymes may be a commercial preparation. Examples of commercial cellulolytic protein preparations suitable for use in the present invention include, for example, CELLICTM Ctec (Novozymes A/S), CELLUCLASTTM (Novozymes NS), NOVOZYMTM 188 (Novozymes A/S), CELLUZYMETM (Novozymes A/S), CEREFLOTM (Novozymes A/S), and ULTRAFLOTM (Novozymes A/S), ACCELERASETM (Genencor Int.), LAMINEXTM (Genencor Int.), SPEZYMETM CP (Genencor Int.), ROHAMENTTM 7069 W (Röhm GmbH), FIBREZYME® LDI (Dyadic International, Inc.), FIBREZYME® LBR (Dyadic International, Inc.), or VISCOSTAR® 150L (Dyadic International, Inc.). The cellulase enzymes are added in amounts effective from about 0.001 to about 5.0 wt % of solids, more preferably from about 0.025 to about 4.0 wt % of solids, and most preferably from about 0.005 to about 2.0 wt % of solids. The cellulase enzymes are added in amounts effective from about 0.001 to about 5.0 wt % of solids, more preferably from about 0.025 to about 4.0 wt % of solids, and most preferably from about 0.005 to about 2.0 wt % of solids.
Examples of bacterial endoglucanases that can be used in the methods of the present invention, include, but are not limited to, an 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); 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 methods of the present invention, include, but are not limited to, a Trichoderma reesei endoglucanase I (Penttila et al., 1986, Gene 45: 253-263; GENBANKTM accession no. M15665); Trichoderma reesei endoglucanase II (Saloheimo, et al., 1988, Gene 63:11-22; GENBANKTM accession no. M19373); Trichoderma reesei endoglucanase III (Okada et al., 1988, Appl. Environ. Microbiol. 64: 555-563; GENBANKTM accession no. AB003694); Trichoderma reesei endoglucanase IV (Saloheimo et al., 1997, Eur. J. Biochem. 249: 584-591; GENBANKTM accession no. Y11113); and Trichoderma reesei endoglucanase V (Saloheimo et al., 1994, Molecular Microbiology 13: 219-228; GENBANKTM accession no. 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); Erwinia carotovara endoglucanase (Saarilahti et al., 1990, Gene 90: 9-14); Fusarium oxysporum endoglucanase (GENBANKTM accession no. L29381); Humicola grisea var. thermoidea endoglucanase (GENBANKTM accession no. AB003107); Melanocarpus albomyces endoglucanase (GENBANKTM accession no. MAL515703); Neurospora crassa endoglucanase (GENBANKTM accession no. XM—324477); Humicola insolens endoglucanase V (SEQ ID NO: 20); Myceliophthora thermophila CBS117.65 endoglucanase (SEQ ID NO: 22); basidiomycete CBS 495.95 endoglucanase (SEQ ID NO: 24); basidiomycete CBS 494.95 endoglucanase (SEQ ID NO: 26); Thielavia terrestris NRRL 8126 CEL6B endoglucanase (SEQ ID NO: 28); Thielavia terrestris NRRL 8126 CEL6C endoglucanase (SEQ ID NO: 30); Thielavia terrestris NRRL 8126 CEL7C endoglucanase (SEQ ID NO: 32); Thielavia terrestris NRRL 8126 CEL7E endoglucanase (SEQ ID NO: 34); Thielavia terrestris NRRL 8126 CEL7F endoglucanase (SEQ ID NO: 36); Cladorrhinum foecundissimum ATCC 62373 CEL7A endoglucanase (SEQ ID NO: 38); and Trichoderma reesei strain No. VTT-D-80133 endoglucanase (SEQ ID NO: 40; GENBANKTM accession no. M15665). The endoglucanases of SEQ ID NO: 20, SEQ ID NO: 22, SEQ ID NO: 24, SEQ ID NO: 26, SEQ ID NO: 28, SEQ ID NO: 30, SEQ ID NO: 32, SEQ ID NO: 34, SEQ ID NO: 36, SEQ ID NO: 38, and SEQ ID NO: 40 described above are encoded by the mature polypeptide coding sequence of SEQ ID NO: 19, SEQ ID NO: 21, SEQ ID NO: 23, SEQ ID NO: 25, SEQ ID NO: 27, SEQ ID NO: 29, SEQ ID NO: 31, SEQ ID NO: 33, SEQ ID NO: 35, SEQ ID NO: 37, SEQ ID NO: 39, respectively.
Examples of cellobiohydrolases useful in the methods of the present invention include, but are not limited to, Trichoderma reesei cellobiohydrolase I (SEQ ID NO: 42); Trichoderma reesei cellobiohydrolase II (SEQ ID NO: 44); Humicola insolens cellobiohydrolase I (SEQ ID NO: 46), Myceliophthora thermophila cellobiohydrolase II (SEQ ID NO: 48 and SEQ ID NO: 50), Thielavia terrestris cellobiohydrolase II (CEL6A) (SEQ ID NO: 52), Chaetomium thermophilum cellobiohydrolase I (SEQ ID NO: 54), and Chaetomium thermophilum cellobiohydrolase II (SEQ ID NO: 56). The cellobiohydrolases of SEQ ID NO: 40, SEQ ID NO: 42, SEQ ID NO: 44, SEQ ID NO: 46, SEQ ID NO: 48, SEQ ID NO: 50, SEQ ID NO: 52, and SEQ ID NO: 54 described above are encoded by the mature polypeptide coding sequence of SEQ ID NO: 41, SEQ ID NO: 43, SEQ ID NO: 45, SEQ ID NO: 47, SEQ ID NO: 49, SEQ ID NO: 51, SEQ ID NO: 53, and SEQ ID NO: 55, respectively.
Examples of beta-glucosidases useful in the methods of the present invention include, but are not limited to, Aspergillus oryzae beta-glucosidase (SEQ ID NO: 58); Aspergillus fumigatus beta-glucosidase (SEQ ID NO: 60); Penicillium brasilianum IBT 20888 beta-glucosidase (SEQ ID NO: 62); Aspergillus niger beta-glucosidase (SEQ ID NO: 64); and Aspergillus aculeatus beta-glucosidase (SEQ ID NO: 66). The beta-glucosidases of SEQ ID NO: 58, SEQ ID NO: 60, SEQ ID NO: 62, SEQ ID NO: 64, and SEQ ID NO: 66 described above are encoded by the mature polypeptide coding sequence of SEQ ID NO: 57, SEQ ID NO: 59, SEQ ID NO: 61, SEQ ID NO: 63, and SEQ ID NO: 65, respectively.
The Aspergillus oryzae polypeptide having beta-glucosidase activity can be obtained according to WO 2002/095014. The Aspergillus fumigatus polypeptide having beta-glucosidase activity can be obtained according to WO 2005/047499. The Penicillium brasilianum polypeptide having beta-glucosidase activity can be obtained according to WO 2007/019442. The Aspergillus niger polypeptide having beta-glucosidase activity can be obtained according to Dan et al., 2000, J. Biol. Chem. 275: 4973-4980. The Aspergillus aculeatus polypeptide having beta-glucosidase activity can be obtained according to Kawaguchi et al., 1996, Gene 173: 287-288.
The beta-glucosidase may be a fusion protein. In one aspect, the beta-glucosidase is the Aspergillus oryzae beta-glucosidase variant BG fusion protein of SEQ ID NO: 68 or the Aspergillus oryzae beta-glucosidase fusion protein of SEQ ID NO: 70. In another aspect, the Aspergillus oryzae beta-glucosidase variant BG fusion protein is encoded by the polynucleotide of SEQ ID NO: 67 or the Aspergillus oryzae beta-glucosidase fusion protein is encoded by the polynucleotide of SEQ ID NO: 69.
Other endoglucanases, cellobiohydrolases, and beta-glucosidases are disclosed in numerous Glycosyl Hydrolase families using the classification according to Henrissat B., 1991, A classification of glycosyl hydrolases based on amino-acid sequence similarities, Biochem. J. 280: 309-316, and Henrissat B., and Bairoch A., 1996, Updating the sequence-based classification of glycosyl hydrolases, Biochem. J. 316: 695-696.
Other cellulolytic enzymes that may be used in the present invention are described in EP 495,257, EP 531,315, EP 531,372, WO 89/09259, WO 94/07998, WO 95/24471, WO 96/11262, WO 96/29397, WO 96/034108, WO 97/14804, WO 98/08940, WO 98/012307, WO 98/13465, WO 98/015619, WO 98/015633, WO 98/028411, WO 99/06574, WO 99/10481, WO 99/025846, WO 99/025847, WO 99/031255, WO 2000/009707, WO 2002/050245, WO 2002/0076792, 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. 4,435,307, U.S. Pat. No. 5,457,046, U.S. Pat. No. 5,648,263, U.S. Pat. No. 5,686,593, U.S. Pat. No. 5,691,178, U.S. Pat. No. 5,763,254, and U.S. Pat. No. 5,776,757.
The cellulolytic enzymes used in the methods 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 cellulolytic 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 a cellulolytic enzyme. 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 cellulolytic enzyme to be expressed or isolated. The resulting cellulolytic enzymes produced by the methods described above may be recovered from the fermentation medium and purified by conventional procedures.
Nucleic Acid Constructs
Nucleic acid constructs comprising an isolated polynucleotide encoding a polypeptide of interest, e.g., GH61 polypeptide, operably linked to one or more (several) control sequences may be constructed that direct the expression of the coding sequence in a suitable host cell under conditions compatible with the control sequences.
The isolated polynucleotide may be manipulated in a variety of ways to provide for expression of the polypeptide. Manipulation of the polynucleotide's sequence prior to its insertion into a vector may be desirable or necessary depending on the expression vector. The techniques for modifying polynucleotide sequences utilizing recombinant DNA methods are well known in the art.
The control sequence may be an appropriate promoter sequence, a nucleotide sequence that is recognized by a host cell for expression of a polynucleotide encoding a polypeptide of the present invention. The promoter sequence contains transcriptional control sequences that mediate the expression of the polypeptide. The promoter may be any nucleotide sequence that shows transcriptional activity in the host cell of choice 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 the transcription of the nucleic acid constructs of the present invention, especially in a bacterial host cell, are the promoters obtained from the E. coli lac operon, Streptomyces coelicolor agarase gene (dagA), Bacillus subtilis levansucrase gene (sacB), Bacillus licheniformis alpha-amylase gene (amyL), Bacillus stearothermophilus maltogenic amylase gene (amyM), Bacillus amyloliquefaciens alpha-amylase gene (amyQ), Bacillus licheniformis penicillinase gene (penP), Bacillus subtilis xylA and xylB genes, and prokaryotic beta-lactamase gene (Villa-Kamaroff et al., 1978, Proceedings of the National Academy of Sciences USA 75: 3727-3731), as well as the tac promoter (DeBoer et al., 1983, Proceedings of the National Academy of Sciences USA 80: 21-25). Further promoters are described in “Useful proteins from recombinant bacteria” in Scientific American, 1980, 242: 74-94; and in Sambrook et al., 1989, supra.
Examples of suitable promoters for directing the transcription of the nucleic acid constructs in a filamentous fungal host cell are promoters obtained from the genes for Aspergillus oryzae TAKA amylase, Rhizomucor miehei aspartic proteinase, Aspergillus niger neutral alpha-amylase, Aspergillus niger acid stable alpha-amylase, Aspergillus niger or Aspergillus awamori glucoamylase (glaA), Rhizomucor miehei lipase, Aspergillus oryzae alkaline protease, Aspergillus oryzae triose phosphate isomerase, Aspergillus nidulans acetamidase, Fusarium venenatum amyloglucosidase (WO 00/56900), Fusarium venenatum Daria (WO 00/56900), Fusarium venenatum Quinn (WO 00/56900), Fusarium oxysporum trypsin-like protease (WO 96/00787), 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 IV, Trichoderma reesei endoglucanase V, Trichoderma reesei xylanase I, Trichoderma reesei xylanase II, Trichoderma reesei beta-xylosidase, as well as the NA2-tpi promoter (a modified promoter including a gene encoding a neutral alpha-amylase in Aspergilli in which the untranslated leader has been replaced by an untranslated leader from a gene encoding triose phosphate isomerase in Aspergilli; non-limiting examples include modified promoters including the gene encoding neutral alpha-amylase in Aspergillus niger in which the untranslated leader has been replaced by an untranslated leader from the gene encoding triose phosphate isomerase in Aspergillus nidulans or Aspergillus oryzae); and mutant, truncated, and hybrid promoters thereof.
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 suitable transcription terminator sequence, a sequence recognized by a host cell to terminate transcription. The terminator sequence is operably linked to the 3′ terminus of the nucleotide sequence encoding the polypeptide. Any terminator that is functional in the host cell of choice may be used in the present invention.
Preferred terminators for filamentous fungal host cells are obtained from the genes for Aspergillus oryzae TAKA amylase, Aspergillus niger glucoamylase, Aspergillus nidulans anthranilate synthase, Aspergillus niger alpha-glucosidase, and Fusarium oxysporum trypsin-like protease.
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 a suitable leader sequence, a nontranslated region of an mRNA that is important for translation by the host cell. The leader sequence is operably linked to the 5′ terminus of the nucleotide sequence encoding the polypeptide. Any leader sequence that is functional in the host cell of choice may be used in the present invention.
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 nucleotide sequence 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 of choice may be used in the present invention.
Preferred polyadenylation sequences for filamentous fungal host cells are obtained from the genes for Aspergillus oryzae TAKA amylase, Aspergillus niger glucoamylase, Aspergillus nidulans anthranilate synthase, Fusarium oxysporum trypsin-like protease, and Aspergillus niger alpha-glucosidase.
Useful polyadenylation sequences for yeast host cells are described by Guo and Sherman, 1995, Molecular Cellular Biology 15: 5983-5990.
The control sequence may also be a signal peptide coding sequence that encodes a signal peptide linked to the amino terminus of a polypeptide and directs the encoded polypeptide into the cell's secretory pathway. The 5′ end of the coding sequence of the nucleotide sequence may inherently contain a signal peptide coding sequence naturally linked in translation reading frame with the segment of the coding sequence that encodes the secreted polypeptide. Alternatively, the 5′ end of the coding sequence may contain a signal peptide coding sequence that is foreign to the coding sequence. The foreign signal peptide coding sequence may be required where the coding sequence does not naturally contain a signal peptide coding sequence. Alternatively, the foreign signal peptide coding sequence may simply replace the natural signal peptide coding sequence in order to enhance secretion of the polypeptide. However, any signal peptide coding sequence that directs the expressed polypeptide into the secretory pathway of a host cell of choice, i.e., secreted into a culture medium, may be used in the present invention.
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 stearothermophilus alpha-amylase, Bacillus licheniformis subtilisin, Bacillus licheniformis beta-lactamase, 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 oryzae TAKA amylase, Aspergillus niger neutral amylase, Aspergillus niger glucoamylase, Rhizomucor miehei aspartic proteinase, Humicola insolens cellulase, Humicola insolens endoglucanase V, and Humicola lanuginosa lipase.
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 amino terminus of a polypeptide. The resultant polypeptide is known as a proenzyme or propolypeptide (or a zymogen in some cases). A propeptide is generally inactive and can be converted to a mature active polypeptide 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), Saccharomyces cerevisiae alpha-factor, Rhizomucor miehei aspartic proteinase, and Myceliophthora thermophila laccase (WO 95/33836).
Where both signal peptide and propeptide sequences are present at the amino terminus of a polypeptide, the propeptide sequence is positioned next to the amino terminus of a polypeptide and the signal peptide sequence is positioned next to the amino terminus of the propeptide sequence.
It may also be desirable to add regulatory sequences that allow the regulation of the expression of the polypeptide relative to the growth of the host cell. Examples of regulatory systems are those that cause the 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 systems 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 TAKA alpha-amylase promoter, Aspergillus niger glucoamylase promoter, and Aspergillus oryzae glucoamylase promoter may be used as regulatory sequences. 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 nucleotide sequence encoding the polypeptide would be operably linked with the regulatory sequence.
Expression Vectors
Recombinant expression vectors comprising a polynucleotide encoding a polypeptide of interest, e.g., GH61 polypeptide, a promoter, and transcriptional and translational stop signals may be constructed for expression of the polypeptide in a suitable host cell. The various nucleic acids and control sequences described herein may be joined together to produce a recombinant expression vector that may include one or more (several) convenient restriction sites to allow for insertion or substitution of the nucleotide sequence encoding the polypeptide at such sites. Alternatively, a polynucleotide sequence may be expressed by inserting the nucleotide sequence or a nucleic acid construct comprising the sequence 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 nucleotide sequence. 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 vectors may be linear or closed circular plasmids.
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 vectors preferably contain one or more (several) 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 the dal genes from Bacillus subtilis or Bacillus licheniformis, or markers that confer antibiotic resistance such as ampicillin, kanamycin, chloramphenicol, or tetracycline resistance. Suitable markers for yeast host cells are ADE2, HIS3, LEU2, LYS2, MET3, TRP1, and URA3. Selectable markers for use in a filamentous fungal host cell include, but are not limited to, 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 the amdS and pyrG genes of Aspergillus nidulans or Aspergillus oryzae and the bar gene of Streptomyces hygroscopicus. 
The vectors preferably contain 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 polypeptide or any other element of the vector for integration into the genome by homologous or nonhomologous recombination. Alternatively, the vector may contain additional nucleotide sequences 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 preferably contain a sufficient number of nucleic acids, such as 100 to 10,000 base pairs, preferably 400 to 10,000 base pairs, and most preferably 800 to 10,000 base pairs, which have a high degree of 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 nucleotide sequences. 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” is defined herein as a nucleotide sequence 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 pAMβ1 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 ANSI (Gems et al., 1991, Gene 98: 61-67; Cullen et al., 1987, Nucleic Acids Research 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 may be inserted into a host cell to increase production of the gene product. 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 are well known to one skilled in the art (see, e.g., Sambrook et al., 1989, supra).
Host Cells
The nucleic acid constructs or expression vectors comprising an isolated polynucleotide encoding a polypeptide of interest, e.g., GH61 polypeptide, may be introduced into a recombinant host cell for the recombinant production of the polypeptide. A vector comprising a polynucleotide is introduced into a host cell so that the 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 polypeptide and its source.
The host cell may be any cell useful in the recombinant production of a polypeptide, e.g., a prokaryote or a eukaryote.
The prokaryotic host cell may be any Gram positive bacterium or a Gram negative bacterium. Gram positive bacteria include, but not limited to, Bacillus, Streptococcus, Streptomyces, Staphylococcus, Enterococcus, Lactobacillus, Lactococcus, Clostridium, Geobacillus, and Oceanobacillus. Gram negative bacteria include, but not limited to, E. coli, Pseudomonas, Salmonella, Campylobacter, Helicobacter, Flavobacterium, Fusobacterium, Ilyobacter, Neisseria, and Ureaplasma. 
The bacterial host cell may be any Bacillus cell. Bacillus cells include, but are 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.
In a preferred aspect, the bacterial host cell is a Bacillus amyloliquefaciens, Bacillus lentus, Bacillus licheniformis, Bacillus stearothermophilus or Bacillus subtilis cell. In a more preferred aspect, the bacterial host cell is a Bacillus amyloliquefaciens cell. In another more preferred aspect, the bacterial host cell is a Bacillus clausii cell. In another more preferred aspect, the bacterial host cell is a Bacillus licheniformis cell. In another more preferred aspect, the bacterial host cell is a Bacillus subtilis cell.
The bacterial host cell may also be any Streptococcus cell. Streptococcus cells include, but are not limited to, Streptococcus equisimilis, Streptococcus pyogenes, Streptococcus uberis, and Streptococcus equi subsp. Zooepidemicus cells.
In a preferred aspect, the bacterial host cell is a Streptococcus equisimilis cell. In another preferred aspect, the bacterial host cell is a Streptococcus pyogenes cell. In another preferred aspect, the bacterial host cell is a Streptococcus uberis cell. In another preferred aspect, the bacterial host cell is a Streptococcus equi subsp. Zooepidemicus cell.
The bacterial host cell may also be any Streptomyces cell. Streptomyces cells include, but are not limited to, Streptomyces achromogenes, Streptomyces avermitilis, Streptomyces coelicolor, Streptomyces griseus, and Streptomyces lividans cells.
In a preferred aspect, the bacterial host cell is a Streptomyces achromogenes cell. In another preferred aspect, the bacterial host cell is a Streptomyces avermitilis cell. In another preferred aspect, the bacterial host cell is a Streptomyces coelicolor cell. In another preferred aspect, the bacterial host cell is a Streptomyces griseus cell. In another preferred aspect, the bacterial host cell is a Streptomyces lividans cell.
The introduction of DNA into a Bacillus cell may, for instance, be effected by protoplast transformation (see, e.g., Chang and Cohen, 1979, Molecular General Genetics 168: 111-115), by using competent cells (see, e.g., Young and Spizizen, 1961, Journal of Bacteriology 81: 823-829, or Dubnau and Davidoff-Abelson, 1971, Journal of Molecular Biology 56: 209-221), by electroporation (see, e.g., Shigekawa and Dower, 1988, Biotechniques 6: 742-751), or by conjugation (see, e.g., Koehler and Thorne, 1987, Journal of Bacteriology 169: 5271-5278). The introduction of DNA into an E coli cell may, for instance, 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, for instance, be effected by protoplast transformation and electroporation (see, e.g., Gong et al., 2004, Folia Microbiol. (Praha) 49: 399-405), by conjugation (see, e.g., Mazodier et al., 1989, J. Bacteriol. 171: 3583-3585), or by 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, for instance, be effected by electroporation (see, e.g., Choi et al., 2006, J. Microbiol. Methods 64: 391-397) or by conjugation (see, e.g., Pinedo and Smets, 2005, Appl. Environ. Microbiol. 71: 51-57). The introduction of DNA into a Streptococcus cell may, for instance, be effected by natural competence (see, e.g., Perry and Kuramitsu, 1981, Infect. Immun. 32: 1295-1297), by protoplast transformation (see, e.g., Catt and Jollick, 1991, Microbios. 68: 189-207, by electroporation (see, e.g., Buckley et al., 1999, Appl. Environ. Microbiol. 65: 3800-3804) or by 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.
In a preferred aspect, the host cell is a fungal cell. “Fungi” as used herein includes the phyla Ascomycota, Basidiomycota, Chytridiomycota, and Zygomycota (as defined by Hawksworth et al., In, Ainsworth and Bisby's Dictionary of The Fungi, 8th edition, 1995, CAB International, University Press, Cambridge, UK) as well as the Oomycota (as cited in Hawksworth et al., 1995, supra, page 171) and all mitosporic fungi (Hawksworth et al., 1995, supra).
In a more preferred aspect, the fungal host cell is 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, F. A., Passmore, S. M., and Davenport, R. R., eds, Soc. App. Bacteriol. Symposium Series No. 9, 1980).
In an even more preferred aspect, the yeast host cell is a Candida, Hansenula, Kluyveromyces, Pichia, Saccharomyces, Schizosaccharomyces, or Yarrowia cell.
In a most preferred aspect, the yeast host cell is a Saccharomyces carlsbergensis, Saccharomyces cerevisiae, Saccharomyces diastaticus, Saccharomyces douglasii, Saccharomyces kluyveri, Saccharomyces norbensis, or Saccharomyces oviformis cell. In another most preferred aspect, the yeast host cell is a Kluyveromyces lactis cell. In another most preferred aspect, the yeast host cell is a Yarrowia lipolytica cell.
In another more preferred aspect, the fungal host cell is 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.
In an even more preferred aspect, the filamentous fungal host cell is 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.
In a most preferred aspect, the filamentous fungal host cell is an Aspergillus awamori, Aspergillus fumigatus, Aspergillus foetidus, Aspergillus japonicus, Aspergillus nidulans, Aspergillus niger or Aspergillus oryzae cell. In another most preferred aspect, the filamentous fungal host cell is a 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, or Fusarium venenatum cell. In another most preferred aspect, the filamentous fungal host cell is a Bjerkandera adusta, Ceriporiopsis aneirina, Ceriporiopsis aneirina, Ceriporiopsis caregiea, Ceriporiopsis gilvescens, Ceriporiopsis pannocinta, Ceriporiopsis rivulosa, Ceriporiopsis subrufa, Ceriporiopsis subvermispora, Chrysosporium keratinophilum, Chrysosporium lucknowense, Chrysosporium tropicum, Chrysosporium merdarium, Chrysosporium inops, Chrysosporium pannicola, Chrysosporium queenslandicum, Chrysosporium zonatum, Coprinus cinereus, Coriolus hirsutus, Humicola insolens, Humicola lanuginosa, Mucor miehei, Myceliophthora thermophila, Neurospora crassa, Penicillium purpurogenum, Phanerochaete chrysosporium, Phlebia radiata, Pleurotus eryngii, 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 238 023 and Yelton et al., 1984, Proceedings of the National Academy of Sciences USA 81: 1470-1474. 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, Journal of Bacteriology 153: 163; and Hinnen et al., 1978, Proceedings of the National Academy of Sciences USA 75: 1920.
Methods of Production
A polypeptide of interest, e.g., GH61 polypeptide, can be produced by (a) cultivating a cell, which in its wild-type form produces the polypeptide, under conditions conducive for production of the polypeptide; and (b) recovering the polypeptide.
The polypeptide of interest can also be produced by (a) cultivating a recombinant host cell, as described herein, under conditions conducive for production of the polypeptide; and (b) recovering the polypeptide.
In the production methods, the cells are cultivated in a nutrient medium suitable for production of the polypeptide using methods well known in the art. For example, the cell may be cultivated by shake flask cultivation, and small-scale 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 polypeptide 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 polypeptide is secreted into the nutrient medium, the polypeptide can be recovered directly from the medium. If the polypeptide is not secreted into the medium, it can be recovered from cell lysates.
The resulting polypeptide may be recovered using methods known in the art. For example, the polypeptide may be recovered from the nutrient medium by conventional procedures including, but not limited to, centrifugation, filtration, extraction, spray-drying, evaporation, or precipitation.
The polypeptides may be purified by a variety of procedures known in the art including, but not limited to, chromatography, electrophoretic procedures, differential solubility, or extraction (see, e.g., Protein Purification, J.-C. Janson and Lars Ryden, editors, VCH Publishers, New York, 1989) to obtain substantially pure polypeptides.
The present invention is further described by the following examples that should not be construed as limiting the scope of the invention.
EXAMPLES
Media
2×YT plates were composed of 10 g of tryptone, 5 g of yeast extract, 5 g of sodium chloride, 15 g of Bacto Agar, and deionized water to 1 liter.
PDA plates were composed of 39 g of potato dextrose agar and deionized water to 1 liter.
MDU2BP medium was composed of 45 g of maltose, 1 g of MgSO4.7H2O, 1 g of NaCl, 2 g of K2HSO4, 12 g of KH2PO4, 2 g of urea, 500 μl of AMG trace metals solution, and deionized water to 1 liter; pH adjusted to 5.0 and then filter sterilized with a 0.22 μm filtering unit.
AMG trace metals solution was composed of 14.3 g of ZnSO4.7H2O, 2.5 g of CuSO4.5H2O, 0.5 g of NiCl2.6H2O, 13.8 g of FeSO4.H2O, 8.5 g of MnSO4.7H2O, 3 g of citric acid, and deionized water to 1 liter.
YEG medium was composed per liter of 5 g of yeast extract, 20 g of D-glucose, and deionized water to 1 liter.
Example 1
Growth of Myceliophthora thermophila CBS 117.65
Two plugs from a PDA plate of Myceliophthora thermophila CBS 117.65 were inoculated into a 500 ml shake flask containing 100 ml of shake flask medium to obtain culture broth for the purification of a cellobiose dehydrogenase. PDA plates were composed of 39 g of potato dextrose agar and deionized water to 1 liter. The shake flask medium was composed of 15 g of glucose, 4 g of K2HPO4, 1 g of NaCl, 0.2 g of MgSO4.7H2O, 2 g of MES free acid, 1 g of Bacto Peptone, 5 g of yeast extract, 2.5 g of citric acid, 0.2 g of CaCl2.2H2O, 5 g of NH4NO3, 1 ml of trace elements solution, and deionized water to 1 liter. The trace elements solution was composed of 1.2 g of FeSO4.7H2O, 10 g of ZnSO4.7H2O, 0.7 g of MnSO4.H2O, 0.4 g of CuSO4.5H2O, 0.4 g of Na2B4O7.10H2O, 0.8 g of Na2MoO2.2H2O, and deionized water to 1 liter. The shake flask was incubated at 45° C. on an orbital shaker at 200 rpm for 48 hours. Fifty ml of the shake flask broth was used to inoculate a 2 liter fermentation vessel.
A total of 1.8 liters of the fermentation batch medium was added to a two liter glass jacketed fermentor (Applikon Biotechnology, Schiedam, Netherlands). Fermentation feed medium was dosed at a rate of 4 g/l/hour for a period of 72 hours. Fermentation batch medium was composed of 5 g of yeast extract, 176 g of powdered cellulose, 2 g of glucose, 1 g of NaCl, 1 g of Bacto Peptone, 4 g of K2HPO4, 0.2 g of CaCl2.2H2O, 0.2 g of MgSO4.7H2O, 2.5 g of citric acid, 5 g of NH4NO3, 1.8 ml of anti-foam, 1 ml of trace elements solution, and deionized water to 1 liter. The fermentation vessel was maintained at a temperature of 45° C. and pH was controlled using an Applikon 1030 control system (Applikon Biotechnology, Schiedam, Netherlands) to a set-point of 5.6+/−0.1. Air was added to the vessel at a rate of 1 vvm and the broth was agitated by Rushton impeller rotating at 1100 to 1300 rpm. At the end of the fermentation, whole broth was harvested from the vessel and centrifuged at 3000×g to remove the biomass.
Example 2
Purification of Myceliophthora thermophila CBS 117.65 Cellobiose Dehydrogenase
The Myceliophthora thermophila CBS 117.65 harvested broth described in Example 1 was centrifuged in 500 ml bottles at 13,000×g for 20 minutes at 4° C. and then sterile filtered using a 0.22 μm polyethersulfone membrane (Millipore, Bedford, Mass., USA). The filtered broth was concentrated and buffer exchanged with 20 mM Tris-HCl pH 8.5 using a tangential flow concentrator (Pall Filtron, Northborough, Mass., USA) equipped with a 10 kDa polyethersulfone membrane (Pall Filtron, Northborough, Mass., USA). To decrease the amount of pigment, the concentrate was applied to a 60 ml Q-SEPHAROSE BIG BEADTM column (GE Healthcare, Piscataway, N.J., USA) equilibrated with 20 mM Tris-HCl pH 8.5, and eluted stepwise with equilibration buffer containing 600 mM NaCl. Flow-through and eluate fractions were analyzed by SDS-PAGE using 8-16% CRITERIONTM SDS-PAGE gels (Bio-Rad Laboratories, Inc., Hercules, Calif., USA) and stained with GELCODETM Blue protein stain (Thermo Fisher Scientific, Waltham, Mass., USA). The eluate fraction contained cellobiose dehydrogenase (CBDH) as judged by the presence of a band corresponding to the apparent molecular weight of approximately 100 kDa by SDS-PAGE (Schou et al., 1998, Biochem. J. 330: 565-571).
The eluate fraction was concentrated using an AMICONTM ultrafiltration device (Millipore, Bedford, Mass., USA) equipped with a 10 kDa polyethersulfone membrane, and buffer-exchanged into 20 mM Tris-HCl pH 8.5 using a HIPREP® 26/10 desalting column (GE Heathcare, Piscataway, N.J., USA). The desalted material was loaded onto a MONO Q® column (HR 16/10, GE Healthcare, Piscataway, N.J., USA) equilibrated with 20 mM Tris-HCl pH 8.5. Bound proteins were eluted with a linear NaCl gradient from 0 to 500 mM (18 column volumes) in 20 mM Tris-HCl pH 8.5. Fractions were analyzed by SDS-PAGE as described above and the cellobiose dehydrogenase eluted at approximately 350-400 mM NaCl.
Fractions containing cellobiose dehydrogenase were pooled (60 ml) and mixed with an equal volume of 20 mM Tris-HCl pH 7.5 containing 3.4 M ammonium sulfate to yield a final concentration of 1.7 M ammonium sulfate. The sample was filtered (0.2 μM syringe filter, polyethersulfone membrane, Whatman, Maidstone, United Kingdom) to remove particulate matter prior to loading onto a Phenyl Superose column (HR 16/10, GE Healthcare, Piscataway, N.J., USA) equilibrated with 1.7 M ammonium sulfate in 20 mM Tris-HCl pH 7.5. Bound proteins were eluted with a decreasing 1.7→0 M ammonium sulfate gradient (12 column volumes) in 20 mM Tris-HCl pH 7.5. Fractions were analyzed by SDS-PAGE as described above and the cellobiose dehydrogenase eluted at approximately 800 mM ammonium sulfate. The cellobiose dehydrogenase fraction was >90% pure as judged by SDS-PAGE. CBDH activity was confirmed by a 2,6-dichlorophenolindophenol (DCIP) reduction assay in the presence of cellobiose, as described by Schou et al., 1998, supra.
Fractions containing cellobiose dehydrogenase were pooled, concentrated, and buffer exchanged into 20 mM Tris-HCl pH 7.5 by centrifugal concentration in a SORVALL® RT7 centrifuge (Thermo Fisher Scientific, Waltham, Mass., USA) using VIVASPINTM 20 centrifugal concentrators. (10 kDa polyethersulfone membrane; Sartorius, Göttingen, Germany) at 1877×g. Protein concentration was determined using a Microplate BCATM Protein Assay Kit (Thermo Fischer Scientific, Waltham, Mass., USA) in which bovine serum albumin was used as a protein standard.
Example 3
Purification Humicola insolens Cellobiose Dehydrogenase
Humicola insolens DSM 1800 cellobiose dehydrogenase was recombinantly prepared and purified as described by Xu et al., 2001, Enzyme and Microbial Technology 28: 744-653. Protein concentration was determined using a Microplate BCATM Protein Assay Kit.
Example 4
Preparation of Thermoascus aurantiacus GH61A Polypeptide Having Cellulolytic Enhancing Activity
Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity was recombinantly produced in Aspergillus oryzae JaL250 according to WO 2005/074656. The recombinantly produced Thermoascus aurantiacus GH61A polypeptide was first concentrated by ultrafiltration using a 10 kDa membrane, buffer exchanged into 20 mM Tris-HCl pH 8.0, and then purified using a 100 ml Q-SEPHAROSE® Big Beads column (GE Healthcare, Piscataway, N.J., USA) with 600 ml of a 0-600 mM NaCl linear gradient in the same buffer. Fractions of 10 ml were collected and pooled based on SDS-PAGE.
The pooled fractions (90 ml) were then further purified using a 20 ml MONO Q® column (GE Healthcare, Piscataway, N.J., USA) with 500 ml of a 0-500 mM NaCl linear gradient in the same buffer. Fractions of 6 ml were collected and pooled based on SDS-PAGE. The pooled fractions (24 ml) were concentrated by ultrafiltration using a 10 kDa membrane, and chromatographed using a 320 ml SUPERDEX® 200 SEC column (GE Healthcare, Piscataway, N.J., USA) with isocratic elution of approximately 1.3 liters of 150 mM NaCl-20 mM Tris-HCl pH 8.0. Fractions of 20 ml were collected and pooled based on SDS-PAGE. Protein concentration was determined using a Microplate BCATM Protein Assay Kit.
Example 5
Preparation of Trichoderma reesei CEL7A Cellobiohydrolase I
Trichoderma reesei CEL7A cellobiohydrolase I was prepared as described by Ding and Xu, 2004, “Productive cellulase adsorption on cellulose” in Lignocellulose Biodegradation (Saha, B. C. ed.), Symposium Series 889, pp. 154-169, American Chemical Society, Washington, D.C.
Protein concentration was determined using a Microplate BCATM Protein Assay Kit.
Example 6
Preparation of Aspergillus oryzae CEL3A Beta-Glucosidase
Aspergillus oryzae CEL3A beta-glucosidase was recombinantly prepared as described in WO 2004/099228, and purified as described by Langston et al., 2006, Biochim. Biophys. Acta Proteins Proteomics 1764: 972-978. Protein concentration was determined using a Microplate BCATM Protein Assay Kit.
Example 7
Preparation of Trichoderma reesei CEL6A Cellobiohydrolase II
The Trichoderma reesei CEL6A cellobiohydrolase II gene was isolated from Trichoderma reesei RutC30 as described in WO 2005/056772.
The Trichoderma reesei CEL6A cellobiohydrolase II gene was expressed in Fusarium venenatum using pEJG61 as an expression vector according to the procedures described in U.S. Published Application No. 20060156437. Fermentation was performed as described in U.S. Published Application No. 20060156437.
The Trichoderma reesei CEL6A cellobiohydrolase II was desalted and buffer-exchanged into 20 mM sodium acetate-150 mM NaCl pH 5.0 using a HIPREP® 26/10 desalting column according to the manufacturer's instructions. Protein concentration was determined using a Microplate BCATM Protein Assay Kit.
Example 8
Preparation of Thielavia terrestris GH61E Protein Having Cellulolytic Enhancing Activity
Thielavia terrestris GH61E protein having cellulolytic enhancing activity was recombinantly produced in Aspergillus oryzae JaL250 as described in U.S. Pat. No. 7,361,495. The Thielavia terrestris GH61E was desalted and buffer-exchanged into 20 mM sodium acetate-150 mM NaCl pH 5.0 using a HIPREP® 26/10 desalting column according to the manufacturer's instructions. Protein concentration was determined using a Microplate BCATM Protein Assay Kit.
Example 9
Preparation of Trichoderma reesei CEL5A Endoglucanase II
The Trichoderma reesei Family GH5A endoglucanase II gene was cloned into an Aspergillus oryzae expression vector as described below.
Two synthetic oligonucleotide primers, shown below, were designed to PCR amplify the endoglucanase II gene from Trichoderma reesei RutC30 genomic DNA. Genomic DNA was isolated using a DNEASY® Plant Maxi Kit (QIAGEN Inc., Valencia, Calif., USA). An IN-FUSIONTM PCR Cloning Kit (BD Biosciences, Palo Alto, Calif., USA) was used to clone the fragment directly into pAILo2 (WO 2004/099228).









Forward primer:







(SEQ ID NO: 71)









5′-ACTGGATTTACCATGAACAAGTCCGTGGCTCCATTGCT-3′



 



Reverse primer:







(SEQ ID NO: 72)









5′-TCACCTCTAGTTAATTAACTACTTTCTTGCGAGACACG-3′






Bold letters represent coding sequence. The remaining sequence contains sequence identity to the insertion sites of pAILo2 (WO 2004/099228).

Fifty picomoles of each of the primers above were used in an amplification reaction containing 200 ng of Trichoderma reesei genomic DNA, 1× Pfx Amplification Buffer (Invitrogen, Carlsbad, Calif., USA), 6 μl of a 10 mM blend of dATP, dTTP, dGTP, and dCTP, 2.5 units of PLATINUM® Pfx DNA polymerase (Invitrogen Corp., Carlsbad, Calif., USA), and 1 μl of 50 mM MgSO4 (Invitrogen Corp., Carlsbad, Calif., USA) in a final volume of 50 μl. The amplification reaction was incubated in an EPPENDORF® MASTERCYCLER® 5333 (Eppendorf Scientific, Inc., Westbury, N.Y., USA) programmed for 1 cycle at 98° C. for 2 minutes; and 35 cycles each at 94° C. for 30 seconds, 61° C. for 30 seconds, and 68° C. for 1.5 minutes. After the 35 cycles, the reaction was incubated at 68° C. for 10 minutes and then cooled at 10° C. A 1.5 kb PCR reaction product was isolated on a 0.8% GTG® agarose gel (Cambrex Bioproducts, Rutherford, N.J., USA) using 40 mM Tris base-20 mM sodium acetate-1 mM disodium EDTA (TAE) buffer and 0.1 μg of ethidium bromide per ml. The DNA band was visualized with the aid of a DARKREADERTM (Clare Chemical Research, Dolores, Colo., USA). The 1.5 kb DNA band was excised with a disposable razor blade and purified using an ULTRAFREE® DA spin cup (Millipore, Billerica, Mass., USA) according to the manufacturer's instructions.
Plasmid pAILo2 was linearized by digestion with Nco I and Pac I. The plasmid fragment was purified by gel electrophoresis and ultrafiltration as described above. Cloning of the purified PCR fragment into the linearized and purified pAILo2 vector was performed using an IN-FUSIONTM PCR Cloning Kit. The reaction (20 μl) contained 1× IN-FUSIONTM Buffer (BD Biosciences, Palo Alto, Calif., USA), 1×BSA (BD Biosciences, Palo Alto, Calif., USA), 1 μl of IN-FUSIONTM enzyme (diluted 1:10) (BD Biosciences, Palo Alto, Calif., USA), 100 ng of pAILo2 digested with Nco I and Pac I, and 100 ng of the Trichoderma reesei CEL5A endoglucanase II PCR product. The reaction was incubated at room temperature for 30 minutes. A 2 μl sample of the reaction was used to transform E. coli XL10 SOLOPACK® Gold cells (Stratagene, La Jolla, Calif., USA) according to the manufacturer's instructions. After a recovery period, two 100 μl aliquots from the transformation reaction were plated onto 150 mm 2×YT plates supplemented with 100 μg of ampicillin per ml. The plates were incubated overnight at 37° C. A set of 3 putative recombinant clones was recovered from the selection plates and plasmid DNA was prepared from each one using a BIOROBOT® 9600 (QIAGEN Inc., Valencia, Calif., USA). Clones were analyzed by Pci I/Bsp LU11|restriction digestion. One clone with the expected restriction digestion pattern was then sequenced to confirm that there were no mutations in the cloned insert. Clone #3 was selected and designated pAILo27.
Aspergillus oryzae JaL250 (WO 99/61651) protoplasts were prepared according to the method of Christensen et al., 1988, Bio/Technology 6: 1419-1422. Five micrograms of pAILo27 (as well as pAILo2 as a control) were used to transform Aspergillus oryzae JaL250 protoplasts.
The transformation of Aspergillus oryzae JaL250 with pAILo27 yielded about 50 transformants. Eleven transformants were isolated to individual PDA plates and incubated for 5 days at 34° C.
Confluent spore plates were washed with 3 ml of 0.01% TWEEN® 80 and the spore suspension was used to inoculate 25 ml of MDU2BP medium in 125 ml glass shake flasks. Transformant cultures were incubated at 34° C. with constant shaking at 200 rpm. At day five post-inoculation, cultures were centrifuged at 6000×g and their supernatants collected. Five microliters of each supernatant were mixed with an equal volume of 2× loading buffer (10% beta-mercaptoethanol) and loaded onto a 1.5 mm 8%-16% Tris-Glycine SDS-PAGE gel and stained with SIMPLYBLUETM SafeStain (Invitrogen Corp., Carlsbad, Calif., USA). SDS-PAGE profiles of the culture broths showed that ten out of eleven transformants produced a new protein band of approximately 45 kDa. Transformant number 1, designated Aspergillus oryzae JaL250AILo27, was cultivated in a fermentor.
Shake flask medium was composed of 50 g of sucrose, 10 g of KH2PO4, 0.5 g of CaCl2, 2 g of MgSO4.7H2O, 2 g of K2SO4, 2 g of urea, 10 g of yeast extract, 2 g of citric acid, 0.5 ml of trace metals solution, and deionized water to 1 liter. The trace metals solution was composed per liter of 13.8 g of FeSO4.7H2O, 14.3 g of ZnSO4.7H2O, 8.5 g of MnSO4.H2O, 2.5 g of CuSO4.5H2O, 3 g of citric acid, and deionized water to 1 liter.
One hundred ml of shake flask medium was added to a 500 ml shake flask. The shake flask was inoculated with two plugs of Aspergillus oryzae JaL250AILo27 from a PDA plate and incubated at 34° C. on an orbital shaker at 200 rpm for 24 hours. Fifty ml of the shake flask broth was used to inoculate a 3 liter fermentation vessel.
Fermentation batch medium was composed of 10 g of yeast extract, 24 g of sucrose, 5 g of (NH4)2SO4, 2 g of KH2PO4, 0.5 g of CaCl2.2H2O, 2 g of MgSO4.7H2O, 1 g of citric acid, 2 g of K2SO4, 0.5 ml of anti-foam, 0.5 ml of trace metals solution, and deionized water to 1 liter. Trace metals solution was composed of 13.8 g of FeSO4.7H2O, 14.3 g of ZnSO4.7H2O, 8.5 g of MnSO4.H2O, 2.5 g of CuSO4.5H2O, 3 g of citric acid, and deionized water to 1 liter. Fermentation feed medium was composed of maltose.
A total of 1.8 liters of the fermentation batch medium was added to an Applikon Biotechnology three liter glass jacketed fermentor. Fermentation feed medium was dosed at a rate of 0 to 4.4 g/l/hr for a period of 185 hours. The fermentation vessel was maintained at a temperature of 34° C. and pH was controlled using an Applikon 1030 control system to a set-point of 6.1+/−0.1. Air was added to the vessel at a rate of 1 vvm and the broth was agitated by Rushton impeller rotating at 1100 to 1300 rpm. At the end of the fermentation, whole broth was harvested from the vessel and centrifuged at 3000×g to remove the biomass. The supernatant was sterile filtered and stored at 5 to 10° C.
The supernatant was desalted and buffer-exchanged into 20 mM sodium acetate-150 mM NaCl pH 5.0 using a HIPREP® 26/10 desalting column according to the manufacturer's instructions. Protein concentration was determined using a Microplate BCATM Protein Assay Kit.
Example 10
Preparation of Recombinant Myceliophthora thermophila CBS 202.75 Cel6A Cellobiohydrolase II
Myceliophthora thermophila CBS 202.75 was grown in 100 ml of YEG medium in a baffled shake flask at 45° C. for 2 days with shaking at 200 rpm. Mycelia were harvested by filtration using MIRACLOTH® (Calbiochem, La Jolla, Calif., USA), washed twice in deionized water, and frozen under liquid nitrogen. Frozen mycelia were ground, by mortar and pestle, to a fine powder, and total DNA was isolated using a DNEASY® Plant Maxi Kit (QIAGEN Inc., Valencia, Calif., USA).
A full-length Family 6 cellobiohydrolase gene (cel6a) was isolated from Myceliophthora thermophila CBS 202.75 using a GENOMEWALKERTM Universal Kit (Clontech Laboratories, Inc., Mountain View, Calif., USA) according to the manufacturer's instructions. Briefly, total genomic DNA from Myceliophthora thermophila CBS 202.75 was digested separately with four different restriction enzymes (Dra I, Eco RV, Pvu II, and Stu I) that leave blunt ends. Each batch of digested genomic DNA was then ligated separately to the GENOMEWALKERTM Adaptor (Clontech Laboratories, Inc., Mountain View, Calif., USA) to create four libraries. These libraries were then employed as templates in PCR reactions using two gene-specific primers shown below, one for primary PCR and one for secondary PCR. The primers were designed based on a partial Family 6 cellobiohydrolase gene (cel6a) sequence from Myceliophthora thermophila (WO 2004/056981).









Primer MtCel6a-R4:







(SEQ ID NO: 73)









5′-ATTGGCAGCCCGGATCTGGGACAGAGTCTG-3′



 



Primer MtCel6a-R5:







(SEQ ID NO: 74)









5′-CCGGTCATGCTAGGAATGGCGAGATTGTGG-3′






The primary amplifications were composed of 1 μl (approximately 6 ng) of each library as template, 0.4 mM each of dATP, dTTP, dGTP, and dCTP, 10 pmol of Adaptor Primer 1 (Clontech Laboratories, Inc., Mountain View, Calif., USA), 10 pmol of primer MtCel6a-R4, 1× ADVANTAGE® GC-Melt LA Buffer (Clontech Laboratories, Inc., Mountain View, Calif., USA), and 1.25 units of ADVANTAGE® GC Genomic Polymerase Mix in a final volume of 25 μl. The amplification reactions were incubated in an EPPENDORF® MASTERCYCLER® 5333 programmed for pre-denaturing at 94° C. for 1 minute; 7 cycles each at a denaturing temperature of 94° C. for 30 seconds; annealing and elongation at 72° C. for 5 minutes; and 32 cycles each at 67° C. for 5 minutes.
The secondary amplifications were composed of 1 μl of each primary PCR product as template, 0.4 mM each of dATP, dTTP, dGTP, and dCTP, 10 pmol of Adaptor Primer 2 (Clontech Laboratories, Inc., Mountain View, Calif., USA), 10 pmol of primer MtCel6a-R5, 1× ADVANTAGE® GC-Melt LA Buffer, and 1.25 units of ADVANTAGE® GC Genomic Polymerase Mix in a final volume of 25 μl. The amplifications were incubated in an EPPENDORF® MASTERCYCLER® 5333 programmed for pre-denaturing at 94° C. for 1 minute; 5 cycles each at a denaturing temperature of 94° C. for 30 seconds; annealing and elongation at 72° C. for 5 minutes; and 20 cycles at 67° C. for 5 minutes.
The reaction products were isolated by 1.0% agarose gel electrophoresis using TAE buffer where a 3.5 kb product band from the Eco RV library was excised from the gel, purified using a QIAQUICK® Gel Extraction Kit (QIAGEN, Valencia, Calif., USA) according to the manufacturer's instructions, and sequenced.
DNA sequencing of the 3.5 kb PCR fragment was performed with a Perkin-Elmer Applied Biosystems Model 377 XL Automated DNA Sequencer (Perkin-Elmer/Applied Biosystems, Inc., Foster City, Calif., USA) using dye-terminator chemistry (Giesecke et al., 1992, Journal of Virology Methods 38: 47-60) and primer walking strategy. The following gene specific primers were used for sequencing:








MtCel6a-F2:



5′-GCTGTAAACTGCGAATGGGTTCAG-3′
(SEQ ID NO: 75)


 


MtCel6a-F3:


5′-GGGTCCCACATGCTGCGCCT-3′
(SEQ ID NO: 76)


 


MtCel6a-R8:


5′-AAAATTCACGAGACGCCGGG-3′
(SEQ ID NO: 77)






Nucleotide sequence data were scrutinized for quality and all sequences were compared to each other with assistance of PHRED/PHRAP software (University of Washington, Seattle, Wash., USA). The 3.5 kb sequence was compared and aligned with a partial Family 6 cellobiohydrolase gene (cel6a) sequence from Myceliophthora thermophila (WO 2004/056981).
A gene model for the Myceliophthora thermophila sequence was constructed based on similarity of the encoded protein to homologous glycoside hydrolase Family 6 proteins from Thielavia terrestris, Chaetomium thermophilum, Humicola insolens and Trichoderma reesei. The nucleotide sequence (SEQ ID NO: 47) and deduced amino acid sequence (SEQ ID NO: 48) are shown in FIGS. 1A and 1B. The genomic fragment encodes a polypeptide of 482 amino acids, interrupted by 3 introns of 96, 87, and 180 bp. The % G+C content of the gene and the mature coding sequence are 61.6% and 64%, respectively. Using the SignalP software program (Nielsen et al., 1997, Protein Engineering 10:1-6), a signal peptide of 17 residues was predicted. The predicted mature protein contains 465 amino acids with a molecular mass of 49.3 kDa.
A comparative pairwise global alignment of amino acid sequences was determined using the Needleman-Wunsch algorithm (Needleman and Wunsch, 1970, J. Mol. Biol. 48: 443-453) as implemented in the Needle program of EMBOSS with gap open penalty of 10, gap extension penalty of 0.5, and the EBLOSUM62 matrix. The alignment showed that the deduced amino acid sequence of the Myceliophthora thermophila gene encoding the CEL6A mature protein having cellobiohydrolase activity shared 78.6% and 77.6% identity (excluding gaps) to the deduced amino acid sequences of two glycoside hydrolase Family 6 proteins from Chaetomium thermophilum and Humicola insolens, respectively (GeneSeqP accession numbers ADP84824 and AAW44853, respectively).
Two synthetic oligonucleotide primers shown below were designed to PCR amplify the Myceliophthora thermophila cellobiohydrolase gene from genomic DNA prepared using a DNEASY® Plant Maxi Kit for construction of an Aspergillus oryzae expression vector. An IN-FUSIONTM Cloning Kit was used to clone the fragment directly into the expression vector pAILo2, without the need for restriction digestion and ligation.









MtCel6a-F4:







(SEQ ID NO: 78)









5′-ACTGGATTTACCATGGCCAAGAAGCTTTTCATCACC-3′



 



MtCel6a-R9:







(SEQ ID NO: 79)









5′-TCACCTCTAGTTAATTAATTAGAAGGGCGGGTTGGCGT-3′






Bold letters represent coding sequence. The remaining sequence is homologous to the insertion sites of pAILo2.
Fifty picomoles of each of the primers above were used in an amplification reaction composed of 100 ng of Myceliophthora thermophila genomic DNA, 1× ADVANTAGE® GC-Melt LA Buffer, 0.4 mM each of dATP, dTTP, dGTP, and dCTP, and 1.25 units of ADVANTAGE® GC Genomic Polymerase Mix in a final volume of 25 μl. The amplification reaction was incubated in an EPPENDORF® MASTERCYCLER® 5333 programmed for 1 cycle at 94° C. for 1 minutes; and 30 cycles each at 94° C. for 30 seconds, 62° C. for 30 seconds, and 72° C. for 2 minutes. The heat block then went to a 4° C. soak cycle.
The reaction products were isolated by 1.0% agarose gel electrophoresis using TAE buffer where a 1842 bp product band was excised from the gel, and purified using a QIAQUICK® Gel Extraction Kit according to the manufacturer's instructions.
Plasmid pAILo2 was digested with Nco I and Pac I, isolated by 1.0% agarose gel electrophoresis using TAE buffer, and purified using a QIAQUICK® Gel Extraction Kit according to the manufacturer's instructions.
The gene fragment and the digested vector were ligated together using an IN-FUSIONTM Cloning Kit resulting in pSMai180 (FIG. 2) in which transcription of the cellobiohydrolase gene was under the control of a NA2-tpi promoter (a hybrid of promoters from the genes for Aspergillus niger neutral alpha-amylase and Aspergillus oryzae triose phosphate isomerase). The ligation reaction (50 μl) was composed of 1× IN-FUSIONTM Buffer, 1×BSA, 1 μl of IN-FUSIONTM enzyme (diluted 1:10), 100 ng of pAILo2 digested with Nco I and Pac I, and 50 ng of the Myceliophthora thermophila cel6a purified PCR product. The reaction was incubated at room temperature for 30 minutes. One μl of the reaction was used to transform E. coli XL10 SOLOPACK® Gold Supercompetent cells (Stratagene, La Jolla, Calif., USA). An E. coli transformant containing pSMai180 was detected by restriction digestion and plasmid DNA was prepared using a BIOROBOT® 9600. The Myceliophthora thermophila cel6a insert in pSMai180 was confirmed by DNA sequencing.
The same 1842 bp PCR fragment was cloned into pCR®2.1-TOPO vector (Invitrogen, Carlsbad, Calif., USA) using a TOPO TA CLONING® Kit to generate pSMai182 (FIG. 3). The Myceliophthora thermophila cel6a insert in pSMai182 was confirmed by DNA sequencing. E. coli pSMai182 was deposited with the Agricultural Research Service Patent Culture Collection, Northern Regional Research Center, 1815 University Street, Peoria, Ill., 61604, on Sep. 6, 2007.
The Myceliophthora thermophila Family 6 cellobiohydrolase cel6a gene was expressed in Aspergillus oryzae JaL355 as described below.
Aspergillus oryzae JaL355 (WO 2002/40694) protoplasts were prepared according to the method of Christensen et al., 1988, supra. Three μg of pSMai180 were used to transform Aspergillus oryzae JaL355. The transformation of Aspergillus oryzae JaL355 with pSMai180 yielded about 50 transformants. Twenty transformants were isolated to individual Minimal medium plates.
Confluent Minimal Medium plates of the 20 transformants were washed with 5 ml of 0.01% TWEEN® 20 and inoculated separately into 25 ml of MDU2BP medium in 125 ml glass shake flasks and incubated at 34° C. with shaking at 250 rpm. After 5 days incubation, 5 μl of supernatant from each culture were analyzed using CRITERION® Tris-HCl gels (Bio-Rad Laboratories, Inc., Hercules, Calif., USA) and a CRITERION® Cell (Bio-Rad Laboratories, Inc., Hercules, Calif., USA), according to the manufacturer's instructions. The resulting gel was stained with BIO-SAFETM Coomassie Stain (Bio-Rad Laboratories, Inc., Hercules, Calif., USA). SDS-PAGE profiles of the cultures showed that the majority of the transformants had a major band of approximately 70 kDa.
A confluent plate of one transformant, designated transformant 14, was washed with 10 ml of 0.01% TWEEN® 20 and inoculated into a 2 liter Fernbach flask containing 500 ml of MDU2BP medium. The culture was harvested on day 5 and filtered using a 0.22 μm EXPRESSTM Plus Membrane (Millipore, Bedford, Mass., USA).
The filtered broth 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 20 mM Tris-HCl pH 8.0. The concentrated and buffer exchanged broth was adjusted to 20 mM Tris-HCl pH 8.0-1.2 M (NH4)2SO4 and applied to a Phenyl SUPEROSETM column (HR 16/10, GE Healthcare, Piscataway, N.J., USA) equilibrated with 20 mM Tris-HCl pH 8.0-1.2 M (NH4)2SO4. Bound proteins were eluted with a linear gradient over 10 column volumes from 300→0 mM (NH4)2SO4 in 20 mM Tris-HCl pH 8.0. SDS-PAGE of collected fractions showed a major band at approximately 70 kDa. These fractions were then pooled, concentrated, and buffer exchanged by centrifugal concentration using a VIVASPINTM 20 centrifugal concentrators (10 kDa polyethersulfone membrane, Sartorius, Göttingen, Germany) into 20 mM Tris-HCl pH 8.0. Protein concentration was determined using a Microplate BCATM Protein Assay Kit.
Example 11
Microcrystalline Cellulose Assay
A 5% microcrystalline cellulose slurry was prepared by addition of 2.5 g of AVICEL® PH101 (FMC, Philadelphia, Pa., USA) to a graduated 50 ml screw-cap conical tube followed by approximately 40 ml of double-distilled water. The conical tube was then mixed thoroughly by shaking/vortexing, and adjusted to 50 ml total with double-distilled water and mixed again. Contents of the tube were then quickly transferred to a 100 ml beaker and stirred rapidly with a magnetic stirrer. Five hundred μl aliquots of the 5% AVICEL® slurry were pipetted into each well of a 2.2 ml deep-well plate (Axygen, Union City, Calif., USA) using a 1000 μl micropipette with a wide aperture tip (end of tip cut off about 2 mm from the base). Three hundred microliters of double-distilled water and 100 μl of 500 mM sodium acetate-10 mM MnSO4 pH 5 were then added to each well of the plate. Enzyme mixtures were prepared and then added simultaneously to all wells in a volume of 100 μl, for a total of 1 ml in each reaction. The plate was then sealed using an ALPS-300TM plate heat sealer (Abgene, Epsom, United Kingdom), mixed thoroughly, and incubated at 50° C. for approximately 3 days. All experiments were performed in triplicate.
Primary analysis of the microcrystalline cellulose conversion reactions was performed using an Agilent 1100 HPLC (Agilent Technologies, Inc., Santa Clara, Calif., USA) equipped with an AMINEXTM HPX 87H column (Bio-Rad Laboratories, Inc., Hercules, Calif., USA). After approximately 3 days, the deep-well plate was removed from the incubator and chilled overnight to 4° C. The plate was then mixed well by inversion and briefly centrifuged at 52×g in a Sorvall RT7 (Thermo Fisher Scientific, Waltham, Mass., USA) for 10 seconds. Samples were then mixed by pipetting, and 200 μl from each well were transferred to a MULTISCREEN®-HV (Millipore, Bedford, Mass., USA) centrifuge filter plate assembly. The centrifuge filter plate assembly was centrifuged at 2000×g in a SORVALL® RT7 centrifuge (Thermo Fisher Scientific, Waltham, Mass., USA) for 20 minutes. The filtrates were transferred to a 96 well autosampler plate (Agilent Technologies, Inc., Santa Clara, Calif., USA) and diluted 1:1 with 5 mM H2SO4, sealed with silicon sealing mat (Agilent Technologies, Inc., Santa Clara, Calif., USA), and inserted into an HPLC injector module (set to 4° C.) for injection of 20 μl onto a CATION HTM guard column (Bio-Rad Laboratories, Inc., Hercules, Calif., USA) connected to an AMINEXTM HPX 87H column with elution by 5 mM H2SO4. Sugars were detected by refractive index detector (Agilent Technologies, Inc., Santa Clara, Calif., USA) with quantitation by integration compared to purified sugar standards.
All HPLC data processing was performed using MICROSOFT EXCELTM software (Microsoft, Richland, Wash., USA). Measured sugar concentrations were adjusted for the appropriate dilution factor. Glucose and cellobiose were measured individually. However, to calculate total conversion the glucose and cellobiose values were combined. Cellobiose concentration was multiplied by 1.053 in order to convert to glucose equivalents and added to the glucose concentration. In order to calculate % conversion, a 100% conversion point was set based on a high cellulase control (a very high cellulase broth loading, 50-100 mg Trichoderma reesei cellulase per gram cellulose), and all values were divided by this number and then multiplied by 100. Triplicate data points were averaged and standard deviation was calculated.
Example 12
Effect on Cellulase Hydrolysis of Microcrystalline Cellulose by the Addition of Both Thermoascus aurantiacus GH61A Polypeptide Having Cellulolytic Enhancing Activity and Myceliophthora thermophila Cellobiose Dehydrogenase
Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity and Myceliophthora thermophila cellobiose dehydrogenase were tested for their ability to enhance the hydrolysis of microcrystalline cellulose by each of four individual cellulases (Trichoderma reesei CEL7A cellobiohydrolase I, Trichoderma reesei CEL6A cellobiohydrolase II, Trichoderma reesei CEL5A endoglucanase II, or Myceliophthora thermophila Cel6A cellobiohydrolase II). The microcrystalline cellulose hydrolysis assay was performed as described in Example 11 with the individual cellulase enzymes (Trichoderma reesei CEL7A cellobiohydrolase I (12.5 mg protein per g of cellulose), Trichoderma reesei CEL6A cellobiohydrolase II (12.5 mg protein per g of cellulose), Trichoderma reesei CEL5A endoglucanase II (5 mg protein per g of cellulose), or Myceliophthora thermophila Cel6A cellobiohydrolase II (12.5 mg protein per g of cellulose), the individual components Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity (12.5 mg protein per g of cellulose) and Myceliophthora thermophila cellobiose dehydrogenase (5 mg protein per g of cellulose), and combinations of the individual cellulase components (the same loadings as above for individual cellulases) with either addition of Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity (12.5 mg protein per g of cellulose) or addition of Myceliophthora thermophila cellobiose dehydrogenase (5 mg protein per g of cellulose), or addition of both Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity (12.5 mg protein per g of cellulose) and Myceliophthora thermophila cellobiose dehydrogenase (5 mg protein per g of cellulose). Data was collected and analyzed, as described in Example 11, after 88 hours of incubation at 50° C.
The results are shown in FIG. 4. The addition of Myceliophthora thermophila cellobiose dehydrogenase (5 mg protein per g of cellulose) resulted in moderate inhibition of microcrystalline cellulose conversion by each of the four cellulases tested in this example. The addition of Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity (12.5 mg protein per g of cellulose) resulted in modest or no inhibition of microcrystalline cellulose conversion by each of the four cellulases tested in this example. The addition of both Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity (12.5 mg protein per g of cellulose) and Myceliophthora thermophila cellobiose dehydrogenase (5 mg protein per g of cellulose) resulted in a significant enhancement—a 1.7-fold enhancement for Trichoderma reesei CEL7A cellobiohydrolase I, a 1.8-fold enhancement for Trichoderma reesei CEL6A cellobiohydrolase II, a 3.5-fold enhancement for Trichoderma reesei CEL5A endoglucanase II, and a 1.7-fold enhancement for Myceliophthora thermophila Cel6A cellobiohydrolase II—in microcrystalline cellulose conversion by each of the four cellulases tested in this example. Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity (12.5 mg protein per g of cellulose) alone or Myceliophthora thermophila cellobiose dehydrogenase (5 mg protein per g of cellulose) alone showed no conversion of microcrystalline cellulose in the absence of cellulase.
Example 13
Effect of Thermoascus aurantiacus GH61A Polypeptide Having Cellulolytic Enhancing Activity and Humicola insolens Cellobiose Dehydrogenase on Enzymatic Hydrolysis of Microcrystalline Cellulose
Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity and Humicola insolens cellobiose dehydrogenase were tested for their ability to enhance the hydrolysis of microcrystalline cellulose by each of three individual cellulases (Trichoderma reesei CEL7A cellobiohydrolase I, Trichoderma reesei CEL5A endoglucanase II, or Aspergillus oryzae CEL3A beta-glucosidase) or binary combinations of two cellulases (Trichoderma reesei CEL7A cellobiohydrolase I combined with Trichoderma reesei CEL5A endoglucanase II, or Aspergillus oryzae CEL3A beta-glucosidase combined with Trichoderma reesei CEL5A endoglucanase II).
The microcrystalline cellulose hydrolysis assay was performed as described in Example 11 with the individual cellulase enzymes or binary cellulase mixtures (Trichoderma reesei CEL7A cellobiohydrolase I (10 mg protein per g of cellulose), Trichoderma reesei CEL5A endoglucanase II (10 mg protein per g of cellulose), Aspergillus oryzae CEL3A beta-glucosidase (10 mg protein per g of cellulose), Trichoderma reesei CEL7A cellobiohydrolase I (10 mg protein per g of cellulose) combined with Trichoderma reesei CEL5A endoglucanase II (10 mg protein per g of cellulose), or Aspergillus oryzae CEL3A beta-glucosidase (10 mg protein per g of cellulose) combined with Trichoderma reesei CEL5A endoglucanase II (10 mg protein per g of cellulose), the individual components Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity (10 mg protein per g of cellulose) and Humicola insolens cellobiose dehydrogenase (1 mg protein per g of cellulose), and combinations of the individual cellulase components or binary cellulase mixtures (the same loadings as above for individual cellulases or binary cellulase mixtures) with either addition of Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity (10 mg protein per g of cellulose) or addition of Humicola insolens cellobiose dehydrogenase (1 mg protein per g of cellulose), or addition of both Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity (10 mg protein per g of cellulose) and Humicola insolens cellobiose dehydrogenase (1 mg protein per g of cellulose). Data was collected and analyzed, as described in Example 11, after 72 hours of incubation at 50° C.
The results are shown in FIG. 5. The addition of Humicola insolens cellobiose dehydrogenase (1 mg protein per g of cellulose) resulted in modest inhibition of microcrystalline cellulose conversion by Trichoderma reesei CEL7A cellobiohydrolase I (10 mg protein per g of cellulose) or by Trichoderma reesei CEL7A cellobiohydrolase I (10 mg protein per g of cellulose) combined with Trichoderma reesei CEL5A endoglucanase II (10 mg protein per g of cellulose), and resulted in insignificant inhibition of microcrystalline cellulose conversion by each of the other cellulases or binary cellulase combinations tested in this example. The addition of Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity (10 mg protein per g of cellulose) resulted in modest inhibition of microcrystalline cellulose conversion by Trichoderma reesei CEL7A cellobiohydrolase I (10 mg protein per g of cellulose) or for Trichoderma reesei CEL7A cellobiohydrolase I (10 mg protein per g of cellulose) combined with Trichoderma reesei CEL5A endoglucanase II (10 mg protein per g of cellulose), and resulted in insignificant inhibition of microcrystalline cellulose conversion by each of the other cellulases or binary cellulase combinations tested.
The addition of both Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity (10 mg protein per g of cellulose) and Humicola insolens cellobiose dehydrogenase (1 mg protein per g of cellulose) resulted in a significant enhancement—a 1.8-fold enhancement for Trichoderma reesei CEL7A cellobiohydrolase I, a 3.5-fold enhancement for Trichoderma reesei CEL5A endoglucanase II, a 4-fold enhancement for Aspergillus oryzae CEL3A beta-glucosidase, a 2-fold enhancement for Trichoderma reesei CEL7A cellobiohydrolase I combined with Trichoderma reesei CEL5A endoglucanase II, and a 3-fold enhancement for Aspergillus oryzae CEL3A beta-glucosidase combined with Trichoderma reesei CEL5A endoglucanase II—in microcrystalline cellulose conversion by each of the individual cellulases or binary cellulase combinations tested. The individual components Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity (10 mg protein per g of cellulose) or Humicola insolens cellobiose dehydrogenase (1 mg protein per g of cellulose), or the combination of both Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity (10 mg protein per g of cellulose) and Humicola insolens cellobiose dehydrogenase (1 mg protein per g of cellulose) showed no conversion of microcrystalline cellulose in the absence of cellulase.
Example 14
Effect of Thermoascus aurantiacus GH61A Polypeptide Having Cellulolytic Enhancing Activity and Myceliophthora thermophila Cellobiose Dehydrogenase on Enzymatic Hydrolysis of Microcrystalline Cellulose in the Presence or Absence of EDTA
Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity and Myceliophthora thermophila cellobiose dehydrogenase were tested for their ability to enhance the hydrolysis of microcrystalline cellulose by Trichoderma reesei CEL7A cellobiohydrolase I, either in the presence or absence of EDTA. The microcrystalline cellulose hydrolysis assay was performed as described in Example 11 with the individual cellulase enzyme Trichoderma reesei CEL7A cellobiohydrolase I (10 mg protein per g of cellulose), the individual components Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity (10 mg protein per g of cellulose) and Myceliophthora thermophila cellobiose dehydrogenase (1 mg protein per g of cellulose), and combinations of the individual cellulase Trichoderma reesei CEL7A cellobiohydrolase I (10 mg protein per g of cellulose) with either addition of Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity (10 mg protein per g of cellulose) or addition of Myceliophthora thermophila cellobiose dehydrogenase (1 mg protein per g of cellulose), or addition of both Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity (10 mg protein per g of cellulose) and Myceliophthora thermophila cellobiose dehydrogenase (1 mg protein per g of cellulose). All experiments were conducted in parallel in either the presence or absence of 2 mM EDTA. Data was collected and analyzed, as described in Example 11, after 72 hours of incubation at 50° C.
The results are shown in FIG. 6. The addition of 2 mM EDTA to Trichoderma reesei CEL7A cellobiohydrolase I (10 mg protein per g of cellulose) showed no significant effect on microcrystalline cellulose conversion. The addition of Myceliophthora thermophila cellobiose dehydrogenase (1 mg protein per g of cellulose) to Trichoderma reesei CEL7A cellobiohydrolase I (10 mg protein per g of cellulose) resulted in modest inhibition of microcrystalline cellulose conversion in the absence of 2 mM EDTA and had no effect on microcrystalline cellulose conversion in the presence of 2 mM EDTA. The addition of Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity (12.5 mg protein per g of cellulose) to Trichoderma reesei CEL7A cellobiohydrolase I (10 mg protein per g of cellulose) resulted in modest or no inhibition of microcrystalline cellulose conversion either in the presence or absence of EDTA. The addition of both Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity (10 mg protein per g of cellulose) and Myceliophthora thermophila cellobiose dehydrogenase (1 mg protein per g of cellulose) to Trichoderma reesei CEL7A cellobiohydrolase I (10 mg protein per g of cellulose) resulted in a significant enhancement of a 1.8-fold increase in microcrystalline cellulose conversion in the absence of EDTA, but no enhancement in the presence of EDTA. This EDTA sensitivity indicated a metal dependency for the cellulose conversion enhancing effect provided by the addition of both Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity and Myceliophthora thermophila cellobiose dehydrogenase to Trichoderma reesei CEL7A cellobiohydrolase I.
Example 15
Microcrystalline Cellulose Conversion Assay of Thermoascus aurantiacus GH61A Polypeptide Having Cellulolytic Enhancing Activity, Thielavia terrstris GH61E Polypeptide Having Cellulolytic Enhancing Activity, and Thielavia terrstris GH61E H19N Variant Having No Cellulolytic Enhancing Activity
Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity, Thielavia terrstris GH61E polypeptide having cellulolytic enhancing activity, and Thielavia terrstris GH61E H19N variant having no cellulolytic enhancing activity were tested for their ability to enhance the cellulolytic capacity of the combination of Aspergillus oryzae CEL3A beta-glucosidase and Trichoderma reesei CEL5A endoglucanase II, either in the presence or absence of Humicola insolens cellobiose dehydrogenase.
The Thielavia terrestris GH61E H19N variant was recombinantly produced in Aspergillus oryzae JaL250 using the procedures described in U.S. Pat. No. 7,361,495. A broth containing the Thielavia terrestris GH61E H19N variant was desalted and buffer-exchanged into 20 mM sodium acetate-150 mM NaCl pH 5.0 using a HIPREP® 26/10 desalting column according to the manufacturer's instructions. Protein concentration was determined using a Microplate BCATM Protein Assay Kit.
A microcrystalline cellulose hydrolysis assay was performed as described in Example 11 to test the enhancing effect of the addition of Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity (1, 2.5, 5, or 10 mg protein per g of cellulose), Thielavia terrestris GH61E polypeptide having cellulolytic enhancing activity (5 mg protein per g of cellulose), or Thielavia terrestris GH61E H19N variant having no cellulolytic enhancing activity (5 mg protein per g of cellulose) to the combination of Aspergillus oryzae CEL3A beta-glucosidase (5 mg protein per g of cellulose) and Trichoderma reesei CEL5A endoglucanase II (5 mg protein per g of cellulose). All experiments were conducted in parallel in either the presence or absence of Humicola insolens cellobiose dehydrogenase (1 mg protein per g of cellulose). Data was collected and analyzed, as described in Example 11, after 72 hours of incubation at 50° C.
The results are shown in FIG. 7. Addition of Humicola insolens cellobiose dehydrogenase (1 mg protein per g of cellulose) to the combination of Aspergillus oryzae CEL3A beta-glucosidase (5 mg protein per g of cellulose) and Trichoderma reesei CEL5A endoglucanase II (5 mg protein per g of cellulose) resulted in no significant change in cellulose conversion. In the absence of Humicola insolens cellobiose dehydrogenase, addition of the Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity (1, 2.5, 5, or 10 mg protein per g of cellulose), Thielavia terrestris GH61E (5 mg protein per g of cellulose), or Thielavia terrestris GH61E H19N variant (5 mg protein per g of cellulose) to the combination of Aspergillus oryzae CEL3A beta-glucosidase (5 mg protein per g of cellulose) and Trichoderma reesei CEL5A endoglucanase II (5 mg protein per g of cellulose) resulted in no significant changes in cellulose conversion. In the presence of Humicola insolens cellobiose dehydrogenase (1 mg protein per g of cellulose), addition of Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity (1, 2.5, 5, or 10 mg protein per g of cellulose) resulted in a Thermoascus aurantiacus GH61A polypeptide having cellulolytic enhancing activity dosage dependent enhancement of between 1.7-fold and 3.5-fold increase in cellulose conversion, with increasing Thermoascus aurantiacus GH61A polypeptide addition, by the combination of Aspergillus oryzae CEL3A beta-glucosidase (5 mg protein per g of cellulose) and Trichoderma reesei CEL5A endoglucanase II (5 mg protein per g of cellulose). In the presence of Humicola insolens cellobiose dehydrogenase (1 mg protein per g of cellulose), addition of Thielavia terrestris GH61E (5 mg protein per g of cellulose) resulted in a large enhancement in cellulose conversion of 5.2-fold by the combination of Aspergillus oryzae CEL3A beta-glucosidase (5 mg protein per g of cellulose) and Trichoderma reesei CEL5A endoglucanase II (5 mg protein per g of cellulose). In the presence of Humicola insolens cellobiose dehydrogenase (1 mg protein per g of cellulose), addition of Thielavia terrestris GH61E H19N variant (5 mg protein per g of cellulose) resulted in no enhancement in cellulose conversion by the combination of Aspergillus oryzae CEL3A beta-glucosidase (5 mg protein per g of cellulose) and Trichoderma reesei CEL5A endoglucanase II (5 mg protein per g of cellulose).
The overall results demonstrated the usefulness of the assay for detecting the ability of GH61 proteins to enhance cellulolytic activity in a cellobiose dehydrogenase background using microcrystalline cellulose (or other pure cellulose) as a substrate and purified cellulase monocomponents or complex cellulase mixtures/broths. The assay can also be modified to include addition of purified lignin to cellulose, or addition of lignocellulosic substrate (raw or pretreated) instead of pure cellulose or cellulose/lignin mixtures, or the addition of other suspected inhibitory or enhancing compounds to cellulase action. The assay allows direct determination of whether a GH61 polypeptide enhances the activity of a cellulase on pure and well-characterized cellulose substrates.
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.

## Claims

1. A method for determining cellulolytic enhancing activity of a GH61 polypeptide, comprising:
(a) incubating a cellulosic material with an enzyme composition comprising a cellobiose dehydrogenase and one or more cellulolytic enzymes in the presence and absence of the GH61 polypeptide; and
(b) measuring the release of sugar from the cellulosic material in the presence and absence of the polypeptide.

2. The method of claim 1, wherein the cellulosic material is selected from the group consisting of microcrystalline cellulose, phosphoric acid swollen cellulose, and bacterial cellulose.

3. The method of claim 1, wherein the one or more (several) cellulolytic enzymes are selected from the group consisting of an endoglucanase, a cellobiohydrolase, and a beta-glucosidase.

4. The method of claim 1, wherein the ratio of the GH61 polypeptide to the cellulosic material is about 1 mg to about 50 mg per g of cellulose.

5. The method of claim 1, wherein the ratio of the cellobiose dehydrogenase to the cellulosic material is about 1 mg to about 10 mg per g of cellulose.

6. The method of claim 1, wherein the ratio of the one or more cellulolytic enzymes to the cellulosic material is about 5 mg to about 50 mg per g of cellulose.

7. The method of claim 1, wherein a GH61 polypeptide having cellulolytic enhancing activity is used as a standard.

8. The method of claim 7, wherein the standard GH61 polypeptide having cellulolytic enhancing activity is selected from the group consisting of SEQ ID NO: 2, SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 14, and SEQ ID NO: 16; and the mature polypeptide thereof.

9. The method of claim 1, wherein the GH61 polypeptide is incubated with the cellulosic material and the enzyme composition comprising the cellobiose dehydrogenase and the one or more (several) cellulolytic enzymes under conditions of pH and temperature that are optimal for the cellobiose dehydrogenase and the one or more cellulolytic enzymes.