title: Back mutations to the TEM-1 beta-lactamase from TRC-1 lead to restored sensitivity to clavulanic acid.
abstract: Back mutations from the TRC-1 beta-lactamase to the TEM-1 enzyme were selected in vitro. The revertant beta-lactamase was obtained from Escherichia coli strain J62.2 carrying plasmid pUK901 which encodes the TRC-1 beta-lactamase. The revertant was obtained after repeated subculture of E. coli J62.2 (pUK901) in amoxycillin 512 mg/L for 5 days. The revertant beta-lactamase had the same pI as TEM-1 (5.4) and had restored inhibition by clavulanic acid (ID50 reduced from 4.2 microM to 0.15 microM). The prevalence of these beta-lactamases in the clinical population may be the result of a two-way flux, with mutations in both forward and backward directions.
authors.affiliation: Department of Medical Microbiology, Medical School, University of Edinburgh.
authors.forename: C J
authors.initials: CJ
authors.lastname: Thomson
authors.forename: S G
authors.initials: SG
authors.lastname: Amyes
mesh_terms: D000658:Amoxicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D019818:Clavulanic Acid; D002969:Clavulanic Acids / Q000494:pharmacology*; D004269:DNA, Bacterial / Q000032:analysis; D004352:Drug Resistance, Microbial / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D007525:Isoelectric Focusing; D009154:Mutation / Q000187:drug effects; D015183:Restriction Mapping; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D002969:Clavulanic Acids; D004269:DNA, Bacterial; D065093:beta-Lactamase Inhibitors; D019818:Clavulanic Acid; D000658:Amoxicillin; C074522:beta-lactamase TRC-1; D001618:beta-Lactamases; C034413:beta-lactamase TEM-1