title: Reversal of clavulanate resistance conferred by a Ser-244 mutant of TEM-1 beta-lactamase as a result of a second mutation (Arg to Ser at position 164) that enhances activity against ceftazidime.
abstract: The mutation of Arg-244 to Ser (Arg-244-->Ser mutation) in the TEM-1 beta-lactamase has been shown to produce resistance to inactivation by clavulanate in the mutant enzyme and resistance to ampicillin plus clavulanate in a strain of Escherichia coli producing this enzyme. The Arg-164-->Ser mutation in the TEM-1 beta-lactamase (TEM-12 enzyme) is known to enhance the activity of the enzyme against ceftazidime, resulting in resistance to the drug in a strain producing the mutant enzyme (D. A. Weber, C. C. Sanders, J. S. Bakken, and J. P. Quinn, J. Infect. Dis. 162:460-465, 1990). The doubly mutated derivative of the TEM-1 enzyme (Ser-164/Ser-244) retains the characteristics of the Ser-164 mutant enzyme, i.e., enhanced activity against ceftazidime and sensitivity to inactivation by clavulanate. It also confers the same phenotype as the Ser-164 mutant enzyme, i.e., resistance to ceftazidime and ampicillin, with reversal of this resistance in the presence of clavulanate. Thus, the Arg-164-->Ser mutation in the TEM-1 beta-lactamase suppresses the effect of the Arg-244-->Ser mutation which, by itself, reduces the sensitivity of the enzyme to inactivation by clavulanate.
authors.affiliation: Department of Chemistry, Wayne State University, Detroit, Michigan 48201.
authors.forename: U
authors.initials: U
authors.lastname: Imtiaz
authors.forename: E K
authors.initials: EK
authors.lastname: Manavathu
authors.forename: S
authors.initials: S
authors.lastname: Mobashery
authors.forename: S A
authors.initials: SA
authors.lastname: Lerner
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002442:Ceftazidime / Q000494:pharmacology*; D002942:Circular Dichroism; D019818:Clavulanic Acid; D002969:Clavulanic Acids / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D007700:Kinetics; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D002969:Clavulanic Acids; D065093:beta-Lactamase Inhibitors; D019818:Clavulanic Acid; D002442:Ceftazidime; D001618:beta-Lactamases; C034413:beta-lactamase TEM-1