Structural and Biochemical Characterization of Endo-β-1,4-glucanase from Dictyoglomus thermophilum, a Hyperthermostable and Halotolerant Cellulase

Enzymatic conversion of polysaccharides in the lignocellulosic biomass is currently the subject of intensive research and will be a key technology in future biorefineries. Using a bioinformatics approach, we previously identified a putative endo-β-1,4-glucanase (DtCel5A) from Dictyoglomus thermophilum, a chemoorganotrophic and thermophilic bacterium. Here, we structurally and functionally characterize DtCel5A and show that it is endowed with remarkable thermal and chemical stability. The structural features of DtCel5A and of its complex with cellobiose have been investigated by combining X-ray crystallography and other biophysical studies. Importantly, biochemical assays show that DtCel5A retains its activity on cellulose at high temperatures and at elevated salt concentrations. These features make DtCel5A an enzyme with interesting biotechnological applications for biomass degradation.