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The crystal structure of the nonprocessive cellulase Cel9M from Clostridium cellulolyticum exhibits a dockerin and a catalytic module that interact with the substrate. Comparison of Cel9M with the other structurally related 9 family cellulases suggest differences in the substrate activity between the variants.

Crystallographic analysis of native and mutant forms of cellulase Cel48F and substrate-inhibitor complex crystals reveal seven sub-sites located at two different positions in the enzyme tunnel. Data also indicate that in the processive endo-cellulase, the two sites exhibit different patterns of aromatic residue stacking whereas nonprocessive enzyme show one type of sugar.

Complete cellulose degradation is the first step in the use of biomass as a source of renewable energy. To this end, the engineering of novel cellulase activity, the activity responsible for the hydrolysis of the β-1,4-glycosidic bonds in cellulose, is a topic of great interest. The high-resolution X-ray crystal structure of a multidomain endoglucanase from Clostridium cellulolyticum has been determined at a 1.6-Å resolution. The endoglucanase, Cel9G, is comprised of a family 9 catalytic domain attached to a family III[sub c] cellulose-binding domain. The two domains together form a fiat platform onto which crystalline cellulose is suggested to bind and be fed into the active-site cleft for endolytic hydrolysis. To further dissect the structural basis of cellulose binding and hydrolysis, the structures of Ce19G in the presence of cellobiose, cellotriose, and a DP-10 thio-oligosaccharide inhibitor were resolved at resolutions of 1.7, 1.8, and 1.9 Å, respectively. [ABSTRACT FROM AUTHOR]