Preparation and preliminary X-ray analysis of the catalytic module of β-1,3-xylanase from the marine bacterium Vibrio sp. AX-4

β-1,3-xylanase (1,3-β-D-xylan xylanohydrolase; EC 3.2.1.32) is an enzyme capable of hydrolyzing β-1,3-xylan. The newly cloned β-1,3-xylanase from the marine bacterium Vibrio sp. AX-4 (XYL4) exhibited a modular structure consisting of three modules: an N-terminal catalytic module belonging to glycoside hydrolase family 26 and two C-terminal xylan-binding modules belonging to carbohydrate-binding module family 31. Despite substantial crystallization screening, crystallization of the recombinant XYL4 was not accomplished. However, the deletion mutant of XYL4, composed of a catalytic module without a xylan-binding module, was crystallized. The crystal belonged to space group P2₁2₁2₁, with unit-cell parameters a = 51.6, b = 75.8, c = 82.0 Å. X-ray diffraction data were collected to 1.44 Å resolution.