Polypeptides having alpha-glucosidase activity and polynucleotides encoding same

Abstract

The present invention relates to isolated polypeptides having alpha-glucosidase activity and isolated polynucleotides encoding the polypeptides. The invention also relates to nucleic acid constructs, vectors, and host cells comprising the polynucleotides as well as methods for producing and using the polypeptides.

What is claimed is: 
     
         1 . An isolated polypeptide having alpha-glucosidase activity, selected from the group consisting of:
 (a) a polypeptide having an amino acid sequence which has at least 90% identity with amino acids 20 to 988 of SEQ ID NO: 6;   (b) a polypeptide which is encoded by a polynucleotide which hybridizes under high stringency conditions with (i) nucleotides 58 to 3164 of SEQ ID NO: 5, (ii) the cDNA sequence contained in nucleotides 58 to 3164 of SEQ ID NO: 5, or (iii) a complementary strand of (i) or (ii); and   (c) a variant comprising a conservative substitution, deletion, and/or insertion of one or more amino acids of amino acids 20 to 988 of SEQ ID NO: 6.   
     
     
         2 . The polypeptide of  claim 1 , having an amino acid sequence which has at least 95% identity with amino acids 20 to 988 of SEQ ID NO: 6. 
     
     
         3 . The polypeptide of  claim 1 , having an amino acid sequence which has at least 97% identity with amino acids 20 to 988 of SEQ ID NO: 6. 
     
     
         4 . The polypeptide of  claim 1 , having an amino acid sequence which has at least 99% identity with amino acids 20 to 988 of SEQ ID NO: 6. 
     
     
         5 . The polypeptide of  claim 1 , comprising the amino acid sequence of SEQ ID NO: 6. 
     
     
         6 . The polypeptide of  claim 1 , which consists of SEQ ID NO: 6, or a fragment thereof having alpha-glucosidase activity. 
     
     
         7 . The polypeptide of  claim 1 , which consists of SEQ ID NO: 6. 
     
     
         8 . The polypeptide of  claim 1 , which consists of amino acids 20 to 988 of SEQ ID NO: 6. 
     
     
         9 . The polypeptide of  claim 1 , wherein the polypeptide is a variant comprising a conservative substitution, deletion, and/or insertion of one or more amino acids of amino acids 20 to 988 of SEQ ID NO: 6. 
     
     
         10 . The polypeptide of  claim 1 , which is encoded by the polynucleotide contained in plasmid pSMO216 which is contained in  E. coli  NRRL B-30751, plasmid pHyGe011 which is contained in  E. coli  NRRL B-30750, or plasmid pJSF9b which is contained in  E. coli  NRRL 13-30856. 
     
     
         11 . An isolated polynucleotide comprising a nucleotide sequence which encodes the polypeptide of  claim 1 . 
     
     
         12 . The isolated polynucleotide of  claim 11 , having at least one mutation in the mature polypeptide coding sequence of SEQ ID NO: 5, in which the mutant nucleotide sequence encodes a polypeptide consisting of amino acids 20 to 988 of SEQ ID NO: 6. 
     
     
         13 . A nucleic acid construct comprising the polynucleotide of 11 operably linked to one or more control sequences that direct the production of the polypeptide in an expression host. 
     
     
         14 . A recombinant expression vector comprising the nucleic acid construct of  claim 13 . 
     
     
         15 . A recombinant host cell comprising the nucleic acid construct of  claim 13 . 
     
     
         16 . A method for producing the polypeptide of  claim 1  comprising (a) cultivating a cell, which in its wild-type form is capable of producing the polypeptide, under conditions conducive for production of the polypeptide; and (b) recovering the polypeptide. 
     
     
         17 . A method for producing the polypeptide of  claim 1  comprising (a) cultivating a host cell comprising a nucleic acid construct comprising a nucleotide sequence encoding the polypeptide under conditions conducive for production of the polypeptide; and (b) recovering the polypeptide. 
     
     
         18 . A recombinant host cell comprising a nucleic acid construct comprising a gene encoding a protein of SEQ ID NO: 6 or a protein having at least 95% identity thereto having alpha-glucosidase activity operably linked to a nucleotide sequence encoding a signal peptide selected from the group consisting of: nucleotides 1 to 42 of SEQ ID NO: 1, nucleotides 1 to 145 of SEQ ID NO: 3, and nucleotides 1 to 57 of SEQ ID NO: 5, wherein the gene is heterologous to the nucleotide sequence encoding the signal peptide. 
     
     
         19 . The recombinant host cell of  claim 18 , wherein the host cell is a  Saccharomyces  host cell. 
     
     
         20 . A method for producing a protein comprising cultivating the recombinant host cell of  claim 19  under conditions conductive for production of the protein.