Xylanase B from Clostridium cellulovorans 743B: overexpression, purification, crystallization and X‐ray diffraction analysis

Clostridium cellulovorans produces multi‐enzyme complexes called cellulosomes capable of efficiently degrading cellulosic biomass. There are three xylanase genes containing a sequence corresponding to a dockerin domain that are necessary for constructing cellulosomes in the genome. Among the xylanases encoded by these genes, xylanase B (XynB) contains a catalytic domain belonging to glycoside hydrolase family 10 and a carbohydrate‐binding module (CBM) at the N‐terminus, making it a member of CBM family 22. In this study, XynB was cloned, overexpressed, purified and crystallized. XynB was crystallized using the hanging‐drop vapour‐diffusion method in the presence of 0.2 M sodium acetate trihydrate, 0.1 M Tris–HCl pH 8.5, 32%(w/v) PEG 4000 at 293 K. X‐ray diffraction analysis revealed that the crystal diffracted to 1.95 Å resolution and belonged to space group P212121, with unit‐cell parameters a = 74.28, b = 77.55, c = 88.20 Å, α = β = γ = 90°. The data‐evaluation statistics revealed high quality of the collected data, thereby establishing a solid basis for determination of the structure of cellulosomal xylanase from C. cellulovorans. Cellulosomes are capable of efficiently degrading cellulosic biomass. Crystallization and diffraction analysis of xylanase, which is part of the multi‐enzyme cellulosome of Clostridium cellulovorans 743B, are reported.