title: New cephamycin antibiotic, CS-1170: binding affinity to penicillin-binding proteins and inhibition of peptidoglycan cross-linking reactions in Escherichia coli.
abstract: The binding activity of CS-1170, a new cephamycin antibiotic, to penicillin-binding proteins (PBPs) in Escherichia coli and Proteus species and the potency of this antibiotic in vitro to inhibit enzymes involved in peptidoglycan cross-linking in E. coli were tested. Similar experiments were carried out with the 7alpha-H analog of CS-1170, R-45656, and the results were compared with those obtained with CS-1170. CS-1170 showed high affinities (compared with that of penicillin G) for E. coli PBP-1A, -1Bs, and -3, the PBPs of higher molecular weight, but not PBP-2. It also inhibited the in vitro peptidoglycan cross linking reaction and concomitant release of d-alanine at very low concentrations (approximately its minimal inhibitory concentration). This antibiotic also showed very high affinity for PBP-4, -5, and -6, the PBPs of lower molecular weight, and at extremely low concentrations it inhibited d-alanine carboxypeptidases IA and IB, corresponding to PBP-5/6 and PBP-4, respectively. CS-1170 seemed to be resistant to the beta-lactamase activity of PBP-5 and -6 in E. coli and Proteus species. R-45656 showed as high an affinity for PBP-1A, -1Bs, and -3 as CS-1170, but unlike CS-1170, it had low affinities for PBP-4, -5, and -6. The concentrations of R-45656 required for inhibition of d-alanine carboxypeptidases IA and IB were also much higher than those of CS-1170. R-45656 showed rather low activities in inhibiting the in vitro cross-linking reaction of peptidoglycan and concomitant release of d-alanine. Synergism was observed in 9 of 22 strains examined between CS-1170 and mecillinam, which bound specifically to PBP-2.
mesh_terms: D000560:Amdinocillin / Q000494:pharmacology; D001426:Bacterial Proteins / Q000378:metabolism*; D001667:Binding, Competitive; D002352:Carrier Proteins / Q000378:metabolism*; D002511:Cephalosporins / Q000494:pharmacology*; D002513:Cephamycins / Q000378:metabolism / Q000494:pharmacology*; D004357:Drug Synergism; D004926:Escherichia coli / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D010400:Penicillin G / Q000378:metabolism; D010406:Penicillins / Q000378:metabolism; D010457:Peptidoglycan / Q000096:biosynthesis*; D011485:Protein Binding
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D002511:Cephalosporins; D002513:Cephamycins; D008565:Membrane Proteins; D010406:Penicillins; D010457:Peptidoglycan; D010400:Penicillin G; D000560:Amdinocillin