Crystallization and preliminary X-ray analysis of an acetone carboxylase from Xanthobacter autotrophicus strain Py2.

Acetone carboxylase from Xanthobacter autotrophicus strain Py2 catalyzes the MgATP-dependent carboxylation of acetone to acetoacetate. Interestingly, during this reaction ATP is hydrolyzed to AMP and inorganic phosphate, suggesting a novel carboxylation mechanism. Acetone carboxylase is a heterohexameric protein comprised of three different polypeptides having molecular weights of 86 342, 78 509 and 19 773 Da arranged in an alpha(2)beta(2)gamma(2) quaternary structure. Here, the crystallization and preliminary X-ray data analysis of acetone carboxylase is reported. The acetone carboxylase isolated from the aerobic microorganism X. autotrophicus strain Py2 crystallizes in a primitive orthorhombic point group P222, with unit-cell parameters a = 76.2, b = 122.0, c = 264.2 A. The Matthews coefficient calculation indicates that one alphabetagamma half of the large protein complex is located in the asymmetric unit in this crystal form. Crystals have been obtained that diffract to better than 2.8 A resolution and data have been collected to 3.2 A resolution.