In vivo target of benzylpenicillin in Gaffkya homari
- 1 March 1986
- journal article
- research article
- Published by American Society for Microbiology in Antimicrobial Agents and Chemotherapy
- Vol. 29 (3) , 432-439
- https://doi.org/10.1128/aac.29.3.432
Abstract
It has been established that the DD-carboxypeptidase is the primary in vitro target of benzylpenicillin in Gaffkya homari (W. P. Hammes, Eur. J. Biochem. 70:107-113, 1976). To determine whether this enzyme is also the primary target of benzylpenicillin in vivo, we compared the effects of this beta-lactam, cefmenoxime, cephalothin, and cefoxitin on growth with their acylation of penicillin-binding protein (PBP) 9, the DD-carboxypeptidase. Results of three types of experiments with membrane-walls indicated that PBP 9 is this enzyme and that it is the primary in vitro target of these beta-lactams in the synthesis of sodium dodecyl sulfate (SDS)-insoluble peptidoglycan. First, the acylation of PBP 9 by these beta-lactams paralleled the inhibition of DD-carboxypeptidase and the inhibition of SDS-insoluble peptidoglycan synthesis. Second, the rate of benzylpenicillin release from PBP 9 correlated with the recovery of DD-carboxypeptidase. Third, DD-carboxypeptidase activity was detected in a protein with the same apparent molecular weight as PBP 9 after elution from an SDS-polyacrylamide gel. When intact cells were treated with benzylpenicillin, the minimum growth inhibitory concentration (MGIC) correlated with the concentration of [35S]benzylpenicillin required to acylate PBPs 6 and 9 by 50%. When intact cells were treated with cefmenoxime, cephalothin, or cefoxitin, the MGICs correlated with the concentration of unlabeled beta-lactam required to reduce the subsequent binding of [35S]benzylpenicillin by 50% (ED50) for PBP 6. In contrast, the MGICs of these beta-lactams did not correlate with the ED50s for PBP 9. PBP 9 was not acylated by cefmenoxime or cephalothin at their MGICs, whereas this PBP was fully acylated by cefoxitin at one-tenth of its MGIC. It is suggested that PBP 6 may be a primary target of growth inhibition by benzylpenicillin, cefmenoxime, cephalothin, and cefoxitin; PBP 9, the DD-carboxypeptidase, is dispensable for growth under laboratory conditions; and PBP 9 does not appear to be a primary in vivo target of these beta-lactams, even though this PBP is their primary target in vitro.This publication has 27 references indexed in Scilit:
- Deoxyribonucleic Acid Homology among Strains of the Lobster Pathogen ‘Gaffkya homari’ and Aerococcus viridansMicrobiology, 2000
- Molecular divergence of a major peptidoglycan synthetase with transglycosylase - transpeptidase activities in Escherichia coli — Penicillin-binding protein 1BsBiochemical and Biophysical Research Communications, 1982
- A Role in vivo for Penicillin‐Binding Protein‐4 of Staphylococcus aureusEuropean Journal of Biochemistry, 1981
- The LD-Carboxypeptidase Activity in Gaffkya homari. The Target of the Action of d-Amino Acids or Glycine on the Formation of Wall-Bound PeptidoglycanEuropean Journal of Biochemistry, 1978
- Purification and Characterization of the Penicillin-Binding Protein that is the Lethal Target of Penicillin in Bacillus megaterium and Bacillus licheniformis. Protein Exchange and Complex StabilityEuropean Journal of Biochemistry, 1978
- The Activities in vitro of dd‐Carboxypeptidase and LD‐Carboxypeptidase of Gaffkya homari during Biosynthesis of PeptidoglycanEuropean Journal of Biochemistry, 1978
- Identification of the binding protein which may be the target of penicillin action in Bacillus megateriumNature, 1978
- Steric effects on penicillin-sensitive peptidoglycan synthesis in a membrane-wall system from Gaffkya homariBiochemistry, 1976
- Peptidoglycan biosynthesis in a thermosensitive division mutant of Escherichia coliBiochemistry, 1976
- Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4Nature, 1970