The synthesis of peptidoglycan in an autolysin-deficient mutant of Bacillus licheniformis N.C.T.C. 6346 and the effect of beta-lactam antibiotics, bacitracin and vancomycin.
The synthesis of peptidoglycan by cell-free membrane and membrane+wall preparations from an autolysin-deficient, beta-lactamase-negative mutant of Bacillus licheniformis N.C.T.C. 6346 was studied. The membrane preparation synthesized un-cross-linked polymer, the formation of which was not inhibited by beta-lactam antibiotics. Release of d-alanine by the action of d-alanine carboxypeptidase was inhibited variably according to the antibiotic. This inhibition was reversed by neutral hydroxylamine but not by the action of beta-lactamases or by washing. Bacitracin inhibited peptidoglycan synthesis, but not the d-alanine carboxypeptidase. Examination of peptidoglycan synthesized in the presence of excess of bacitracin showed that synthesis was not restricted to the addition of one disaccharide-pentapeptide unit at each synthetic site, an average of 2-3 disaccharide-pentapeptide units being added. Peptidoglycan synthesis was three- to four-fold more sensitive to vancomycin than was the release of d-alanine by the action of the carboxypeptidase. Incorporation of newly synthesized peptidoglycan into pre-existing cell wall was studied in membrane+wall preparations. This incorporation was catalysed by a benzylpenicillin- and cephaloridine-sensitive transpeptidase. The concentrations of these antibiotics giving 50% inhibition of incorporation were almost identical with those required to inhibit growth of the bacillus. Inhibition of the transpeptidase was reversed by treatment with beta-lactamase or by washing.
D000409:Alanine / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001407:Bacillus / Q000187:drug effects / Q000378:metabolism*; D001414:Bacitracin / Q000494:pharmacology; D002268:Carboxypeptidases; D002462:Cell Membrane / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism; D002511:Cephalosporins / Q000494:pharmacology; D002854:Chromatography, Paper; D004590:Electrophoresis, Paper; D006898:Hydroxylamines; D009154:Mutation; D010406:Penicillins / Q000494:pharmacology; D010457:Peptidoglycan / Q000096:biosynthesis*; D013696:Temperature; D014640:Vancomycin / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D006898:Hydroxylamines; D010406:Penicillins; D010457:Peptidoglycan; D001414:Bacitracin; D014640:Vancomycin; D002268:Carboxypeptidases; D000409:Alanine