title: Crystallographic mapping of beta-lactams bound to a D-alanyl-D-alanine peptidase target enzyme.
abstract: X-ray crystallography has been used to examine the binding of three members of the beta-lactam family of antibiotics to the D-alanyl-D-alanine peptidase from Streptomyces R61, a target of penicillins. Cephalosporin C, the monobactam analog of penicillin G and (2,3)-alpha-methylene benzylpenicillin have been mapped at 2.3 A resolution in the form of acyl-enzyme complexes bound to serine 62. On the basis of the positions of these inhibitors, the binding of a tripeptide substrate for the enzyme, L-lysyl-D-alanyl-D-alanine, has been modeled in the active site. The binding of both inhibitors and substrate is facilitated by hydrogen-bonding interactions with a conserved beta-strand (297-303), which is antiparallel to the beta-lactam's acylamide linkage or the substrate's peptide bond. The active site is similar to that in beta-lactamases.
authors.affiliation: Department of Molecular and Cell Biology, University of Connecticut, Storrs 06269.
authors.forename: J A
authors.initials: JA
authors.lastname: Kelly
authors.forename: J R
authors.initials: JR
authors.lastname: Knox
authors.forename: H
authors.initials: H
authors.lastname: Zhao
authors.forename: J M
authors.initials: JM
authors.lastname: Frère
authors.forename: J M
authors.initials: JM
authors.lastname: Ghaysen
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism; D002268:Carboxypeptidases / Q000378:metabolism; D002511:Cephalosporins / Q000378:metabolism; D003460:Crystallization; D008958:Models, Molecular; D008968:Molecular Conformation; D009842:Oligopeptides / Q000378:metabolism; D010400:Penicillin G / Q000031:analogs & derivatives / Q000378:metabolism; D046929:Serine-Type D-Ala-D-Ala Carboxypeptidase; D014961:X-Ray Diffraction
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D009842:Oligopeptides; C054982:2,3-methylene penam; C043367:lysyl-alanyl-alanine; C025163:cephalosporin C; D002268:Carboxypeptidases; D046929:Serine-Type D-Ala-D-Ala Carboxypeptidase; D010400:Penicillin G