title: In vitro synthesis of peptidoglycan by beta-lactam-sensitive and -resistant strains of Neisseria gonorrhoeae: effects of beta-lactam and other antibiotics.
abstract: The synthesis in vitro of peptidoglycan by Neisseria gonorrhoeae was studied in organisms made permeable to nucleotide precursors by treatment with ether. Optimum synthesis occurred at 30 degrees C in tris(hydroxymethyl)aminomethane-maleate buffer (0.05 M; pH 6) in the presence of 20 mM Mg(2+). The incorporation from uridine 5'-diphosphate-N-acetyl-[(14)C]glucosamine into peptidoglycan, measured after precipitation of the cells with trichloroacetic acid, was sensitive to the beta-lactam antibiotics, bacitracin, diumycin, and tunicamycin and relatively resistant to spectinomycin and tetracycline. Differences in sensitivity between preparations from a beta-lactamase producer and a laboratory segregant derived from it were not great. Synthesized peptidoglycan was also fractionated into sodium dodecyl sulfate-soluble and -insoluble portions. beta-Lactam antibiotics at concentrations equivalent to the minimal inhibitory concentrations for growth of the organisms did not inhibit peptidoglycan synthesis, but rather caused a small enhancement. At higher concentrations, above about 0.5 mug/ml, incorporation into sodium dodecyl sulfate-insoluble material was progressively inhibited, whereas the amount of sodium dodecyl sulfate-soluble product increased greatly, more than compensating for the loss of the precipitable fraction. Similar observations were made with three strains, and also with the beta-lactam clavulanic acid, normally considered as a beta-lactamase inhibitor rather than as itself an effective antibiotic.
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D009344:Neisseria gonorrhoeae / Q000201:enzymology / Q000378:metabolism*; D010457:Peptidoglycan / Q000096:biosynthesis*; D001618:beta-Lactamases / Q000378:metabolism; D047090:beta-Lactams / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D010457:Peptidoglycan; D047090:beta-Lactams; D001618:beta-Lactamases