title: Five novel plasmid-determined beta-lactamases.
abstract: Five novel plasmid-determined beta-lactamases named TLE-1, OXA-4, OXA-5, OXA-6, and OXA-7 were detected in ampicillin-resistant isolates of Escherichia coli and carbenicillin-resistant strains of Pseudomonas aeruginosa. TLE-1 resembled TEM-1 in substrate profile and reactions with inhibitors but differed in isoelectric point (5.55) and enzyme banding pattern on flat-bed electrofocusing.OXA-4, OXA-5, OXA-6, and OXA-7 hydrolyzed oxacillin, methicillin, and cloxacillin readily but differed from OXA-1, OXA-2, and OXA-3 in substrate profiles, inhibitor reactions, and isoelectric points (7.5 to 7.8).OXA-4 and OXA-6 were unusual for members of the OXA group in their sensitivity to inhibition by cloxacillin. OXA-5 and OXA-7 had isoelectric points close to that of SHV-1, emphasizing the need in beta-lactamase classification for studies in addition to isoelectric focusing. These five new enzymes bring the number of plasmid-determined beta-lactamases known in gram-negative organisms to more than 20. The evolution of such enzymatic diversity remains to be explored.
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism; D019818:Clavulanic Acid; D002969:Clavulanic Acids / Q000494:pharmacology; D003023:Cloxacillin / Q000494:pharmacology; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D007525:Isoelectric Focusing; D008970:Molecular Weight; D010957:Plasmids; D011550:Pseudomonas aeruginosa / Q000201:enzymology / Q000235:genetics; D013379:Substrate Specificity; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000032:analysis* / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D002969:Clavulanic Acids; D007202:Indicators and Reagents; D065093:beta-Lactamase Inhibitors; D019818:Clavulanic Acid; D001618:beta-Lactamases; D003023:Cloxacillin