Identification of a putative active site residue in the exo-beta-(1,3)-glucanase of Candida albicans.

Recombinant exo-beta-(1,3)-glucanase from Candida albicans was expressed in Saccharomyces cerevisiae and purified. The enzyme contains a number of short blocks of sequence homology with several genes for cellulases of the family A glucanases including the conserved sequence motif NEP which has previously been shown to be important in the catalytic function of several cellulases. Site directed mutagenesis of this glutamic acid residue in the 1,3 glucanase (E230D, E230Q) decreased the enzymatic activity 15,000- and 400-fold, respectively. This suggests that the E of the NEP participates in catalysis of the exoglucanase and other related glucanases.