Crystallization of Escherichia coli beta-ketoacyl-ACP synthase III and theuse of a dry flash-cooling technique for data collection

beta-Ketoacyl-acyl carrier protein (ACP) synthase III (FabH) is a condensin g enzyme active in the fatty-acid biosynthesis pathway of bacteria. The enz ymes of this pathway provide a set of targets for the discovery of previous ly unknown antibiotics. FabH from Escherichia coli has been crystallized in two crystal forms using the sitting-drop vapor-diffusion technique. The fi rst form crystallized in the orthorhombic space group P2(1)2(1)2(1), with u nit-cell parameters a = 63.1, b = 65.1, c = 166.5 Angstrom; the second form crystallized in the tetragonal space group P4(1)2(1)2, with unit-cell para meters a = b = 72.7, c = 99.8 Angstrom. A flash-cooling technique using no cryoprotectant was utilized in obtaining data from the second type of cryst als.