Polypeptides having cellulase activity

Abstract

The present disclosure relates to CBH II chimera fusion polypeptides, nucleic acids encoding the polypeptides, and host cells for producing the polypeptides.

1 . (canceled) 
     
     
         2 . A recombinant polypeptide selected from the group consisting of a, polypeptide comprising a sequence that is (a) identical to SEQ ID NO:67 and having a C400S mutation; (b) is at least 85% identical to SEQ ID NO:68 and having a C400S mutation; (c) is at least 85% identical to SEQ ID NO:69 and having a C400S mutation; (d) is at least 85% identical to SEQ ID NO:70 and having a C400S mutation; (e) is at least 85% identical to SEQ ID NO:71 and having a C400S mutation; (f) is at least 85% identical to SEQ ID NO:72 and having a C400S mutation; (d) is at least 85% identical to SEQ ID NO:73 and having a C400S mutation; (h) is at least 85% identical to SEQ ID NO:74 and having a C400S mutation; (i) is at least 85% identical to SEQ ID NO:75 and having a C400S mutation; (j) is at least 85% identical to SEQ ID NO:76 and having a C407S mutation; (k) is at least 85% identical to SEQ ID NO:77 and having a C394S mutation; and (l) is at least 85% identical to SEQ ID NO:78 and having a C412S, wherein the foregoing polypeptides have cellulase activity and improved thermostability compared to their corresponding parental (wild-type) protein lacking a Cys→Ser mutation. 
     
     
         3 . The recombinant polypeptide of  claim 2 , wherein the polypeptide has from 1-30 conservative amino acid substitutions except at the position identified below wherein a C→S substitution is present: SEQ ID NO:67 comprising a C400S; SEQ ID NO:68 comprising a C400S; SEQ ID NO:69 comprising a C400S; SEQ ID NO:70 comprising a C400S; SEQ ID NO:71 comprising a C400S; SEQ ID NO:72 comprising a C400S; SEQ ID NO:73 comprising a C400S; SEQ ID NO:74 comprising a C400S; SEQ ID NO:75 comprising a C400S; SEQ ID NO:76 comprising a C407S; SEQ ID NO:77 comprising a C394S, or SEQ ID NO:78 comprising a C412S. 
     
     
         4 - 7 . (canceled) 
     
     
         8 . A polynucleotide encoding a polypeptide of  claim 2 . 
     
     
         9 . A vector comprising a polynucleotide of  claim 8 . 
     
     
         10 . A host cell comprising the polynucleotide of  claim 8 . 
     
     
         11 . A host cell comprising the vector of  claim 9 . 
     
     
         12 . An enzymatic preparation comprising a polypeptide of  claim 2 . 
     
     
         13 . An enzymatic preparation comprising a polypeptide produced by a host cell of  claim 10 . 
     
     
         14 . A method of treating a biomass comprising cellulose, the method comprising contacting the biomass with a polypeptide of  claim 2 . 
     
     
         15 . A method of treating a biomass comprising cellulose, the method comprising contacting the biomass with an enzymatic preparation of  claim 12 .