Binding of cephalothin and cefotaxime to D-ala-D-ala-peptidase reveals a functional basis of a natural mutation in a low-affinity penicillin-binding protein and in extended-spectrum beta-lactamases.
Primary Citation of Related Structures: 1CEF, 1CEG
PubMed Abstract:
Two clinically-important beta-lactam antibiotics, cephalothin and cefotaxime, have been observed by X-ray crystallography bound to the reactive Ser62 of the D-alanyl-D-alanine carboxypeptidase/transpeptidase of Streptomyces sp. R61. Refinement of the two crystal structures produced R factors for 3 sigma (F) data of 0 ...
Two clinically-important beta-lactam antibiotics, cephalothin and cefotaxime, have been observed by X-ray crystallography bound to the reactive Ser62 of the D-alanyl-D-alanine carboxypeptidase/transpeptidase of Streptomyces sp. R61. Refinement of the two crystal structures produced R factors for 3 sigma (F) data of 0.166 (to 1.8 A) and 0.170 (to 2.0 A) for the cephalothin and cefotaxime complexes, respectively. In each complex, a water molecule is within 3.1 and 3.6 A of the acylated beta-lactam carbonyl carbon atom, but is poorly activated by active site residues for nucleophilic attack and deacylation. This apparent lack of good stereochemistry for facile hydrolysis is in accord with the long half-lives of cephalosporin intermediates in solution (20-40 h) and the efficacy of these beta-lactams as inhibitors of bacterial cell wall synthesis. Different hydrogen binding patterns of the two cephalosporins to Thr301 are consistent with the low cefotaxime affinity of an altered penicillin-binding protein, PBP-2x, reported in cefotaxime-resistant strains of Streptococcus pneumoniae, and with the ability of mutant class A beta-lactamases to hydrolyze third-generation cephalosporins.
Related Citations:
The Refined Crystallographic Structure of a Dd-Peptidase Penicillin-Target Enzyme at 1.6 A Resolution Kelly, J.A., Kuzin, A.P. (1995) J Mol Biol 254: 223
Crystallographic Mapping of Beta-Lactams Bound to a D-Alanyl-D-Alanine Peptidase Target Enzyme Kelly, J.A., Knox, J.R., Zhao, H., Frere, J.M., Ghaysen, J.M. (1989) J Mol Biol 209: 281
On the Origin of Bacterial Resistance to Penicillin: Comparison of a Beta-Lactamase and a Penicillin Target Kelly, J.A., Dideberg, O., Charlier, P., Wery, J.P., Libert, M., Moews, P.C., Knox, J.R., Duez, C., Fraipont, C., Joris, B., al., et (1986) Science 231: 1429
2.8-A Structure of Penicillin-Sensitive D-Alanyl Carboxypeptidase-Transpeptidase from Streptomyces R61 and Complexes with Beta-Lactams Kelly, J.A., Knox, J.R., Moews, P.C., Hite, G.J., Bartolone, J.B., Zhao, H., Joris, B., Frere, J.M., Ghuysen, J.M. (1985) J Biol Chem 260: 6449
Organizational Affiliation:
Department of Molecular and Cell Biology, University of Connecticut, Storrs 06269-3125, USA.
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