Cellulase compositions having improved thermostability and synergy

摘要

A variant Cel5a endoglucanase has increased thermostability, increased enzymatic activity and/or increased expression in a host, relative to wild type Cel5a. The improved variant Cel5a endoglucanase may be used to hydrolyze more cellulose at a higher temperature for a more efficient and cost-effective production of biofuels as compared to wild type Cel5a. A variant Cel5a endoglucanase is combined with variant Cel6a and variant Cel7a cellobiohydrolases resulting in more effective hydrolysis of cellulose.

主权项

1. A composition, comprising:
a variant Cel5a endoglucanase having a temperature at which half of the maximal protein activity remains (T50) higher than a T50 of wild type Cel5a endoglucanase and having increased enzymatic activity relative to enzymatic activity of the wild type Cel5a endoglucanase, the variant Cel5a endoglucanase comprising point mutations in a wild type Cel5a amino acid sequence of SEQ ID NO: 7 selected from the group consisting of (a) G293A and S318P/Q/E and (b) G293A and S318P/Q/E and one or more residues selected from the group consisting of E53D, T57N, S79P, T80E, V101I, S133R, N153D, N155E, T156E, G189S, F191V, T233V, G239E, V265T, D271Y, and S309W/L, in which the amino acid residue numbering is based on the numbering of SEQ ID NO: 6; and a cellobiohydrolase selected from the group consisting of Cel6a encoded by SEQ ID NO: 4, Cel7a encoded by SEQ ID NO: 5, and combinations thereof.