Crystallization and preliminary X-ray crystallographic analysis of a putative acetylxylan esterase from Talaromyces cellulolyticus

Acetylxylan esterase (AXE) catalyzes the hydrolytic cleavage of the ester bond between acetic acid and hemicellulose in plant cell walls. A putative AXE gene exhibiting high homology to carbohydrate esterase family 3 was found in the genome database of the fungus Talaromyces cellulolyticus (formerly known as Acremonium cellulolyticus). A truncated form of the protein, the catalytic domain of the enzyme, was prepared and crystallized. The best crystal was obtained at 293 K using 0.17 M ammonium sulfate, 28% PEG 4000, 5%(v/v) glycerol, 0.5%(w/v) n-octyl-β-D-glucoside. X-ray diffraction data were collected to 1.50 Å resolution. The crystal belonged to space group P4₁2₁2 or P4₃2₁2, with unit-cell parameters a = 70.90, b = 70.90, c = 87.09 Å. One enzyme molecule per asymmetric unit gave a crystal volume per protein mass (V_M) of 2.62 ų Da⁻¹ and a solvent content of 53.0%(v/v).