Purification and X-ray crystallographic analysis of 7-keto-8-aminopelargonic acid (KAPA) synthase from Mycobacterium smegmatis.

7-Keto-8-aminopelargonic acid synthase (KAPA synthase; BioF) is an essential enzyme for mycobacterial growth that catalyses the first committed step in the biotin-synthesis pathway. It is a pyridoxal 5′-phosphate (PLP)-dependent enzyme and is a potential drug target. Here, the cloning, expression, purification and crystallization of KAPA synthase from Mycobacterium smegmatis (MsBioF) and the characterization of MsBioF crystals using X-ray diffraction are described. The crystals diffracted to 2.3 A resolution and belonged to the monoclinic space group P21, with unit-cell parameters a = 70.88, b = 91.68, c = 109.84 A, β = 97.8°. According to the molecular weight of MsBioF, the unit-cell parameters and the self-rotation function map, four molecules are present in each asymmetric unit with a V M value of 2.06 A3 Da−1 and a solvent content of 40.20%.