The X-ray crystal structure of beta-ketoacyl [acyl carrier protein] synthase I

The crystal structure of the fatty acid elongating enzyme beta-ketoacyl [ac yl carrier protein] synthase I (KAS I) from Escherichia coli has been deter mined to 2.3 Angstrom resolution by molecular replacement using the recentl y solved crystal structure of KAS II as a search model. The crystal contain s two independent dimers in the asymmetric unit. KAS I assumes the thiolase alpha beta alpha beta alpha fold. Electrostatic potential distribution rev eals an acyl carrier protein docking site and a presumed substrate binding pocket was detected extending the active site. Both subunits contribute to each substrate binding site in the dimer. (C) 1999 Federation of European B iochemical Societies.