title: Contribution of a TEM-1-like beta-lactamase to penicillin resistance in Neisseria gonorrhoeae.
abstract: Two beta-lactamase-producing strains of Neisseria gonorrhoeae were studied. The substrate profile, molecular weight, and isoelectric point of their beta-lactamases were similar to those of the TEM-1 enzyme produced by many gram-negative bacilli. The gonococcal beta-lactamase was cell bound during exponential growth and was most likely located in the periplasm. Penicillin hydrolysis was efficient in intact cells, suggesting that the cell-bound beta-lactamase was freely accessible to benzylpenicillin. Both beta-lactamase-producing strains of N. gonorrhoeae contained an additional multicopy plasmid with a mass of 3.3 megadaltons (Mdal). A spontaneous penicillin-susceptible revertant lacked both beta-lactamase activity and the 3.3-Mdal plasmid, providing evidence for plasmid-mediated penicillin resistance. During a shift from GC medium to rich MOPS medium, growth of the penicillin-susceptible revertant in contrast to that of the plasmid-carrying strain was markedly impaired, suggesting a physiological effect due to the presence of the 3.3-Mdal plasmid.
mesh_terms: D004270:DNA, Circular / Q000032:analysis; D008970:Molecular Weight; D009154:Mutation; D009344:Neisseria gonorrhoeae / Q000187:drug effects / Q000201:enzymology*; D010403:Penicillin Resistance; D010405:Penicillinase / Q000502:physiology*; D010406:Penicillins / Q000494:pharmacology*; D010957:Plasmids; D013104:Spheroplasts
chemical_list: D004270:DNA, Circular; D010406:Penicillins; D010405:Penicillinase