Functional analysis of a novel β-(1,3)-glucanase from Corallococcus sp. strain EGB containing a fascin-like module

Abstract

A novel β-(1,3)-glucanase gene designated lamC, cloned from Corallococcus sp. strain EGB, contains a fascin-like module and a glycoside hydrolase family 16 (GH16) catalytic module. LamC displays broad hydrolytic activity toward various polysaccharides. Analysis of the hydrolytic products revealed that LamC is an exoacting enzyme on β-(1,3)(1,3)- and β-(1,6)-linked glucan substrates and an endoacting enzyme on β-(1,4)-linked glucan and xylan substrates. Site-directed mutagenesis of conserved catalytic Glu residues (E304A and E309A) demonstrated that these activities were derived from the same active site. Excision of the fascin-like module resulted in decreased activity toward β-(1,3)(1,3)-linked glucans. The carbohydratebinding assay showed that the fascin-like module was a novel β-(1,3)-linked glucanbinding module. The functional characterization of the fascin-like module and catalytic module will help us better understand these enzymes and modules.