Xyn30D, a new member of a recently identified group of xylanases, has been purified and crystallized. Xyn30D is a bimodular enzyme composed of an N-terminal catalytic domain belonging to glycoside hydrolase family 30 (GH30) and a C-terminal family 35 carbohydrate-binding domain (CBM35) able to bind xylans and glucuronic acid. Xyn30D shares the characteristic endo mode of action described for GH30 xylanases, with the hydrolysis of the β-(1,4) bonds of xylan being directed by α-1,2-linked glucuronate moieties, which have to be placed at the -2 subsite of the xylanase active site. Crystals of the complete enzyme were obtained and a full data set to 2.3 Å resolution was collected using a synchrotron X-ray source. This represents the first bimodular enzyme with the domain architecture GH30-CBM35. This study will contribute to the understanding of the role that the different xylanases play in the depolymerization of glucuronoxylan.
Keywords: CBM35; GH30; Paenibacillus barcinonensis; xylanase.