title: Detrimental effect of the combination of R164S with G238S in TEM-1 beta-lactamase on the extended-spectrum activity conferred by each single mutation.
abstract: The non-naturally occurring TEM-1 beta-lactamase mutant R164S:G238S, as well as the R164S (TEM-12) and G238S (TEM-19) beta-lactamases, were constructed and expressed in Escherichia coli under isogenic conditions. Comparison of susceptibilities to beta-lactam antibiotics and substrate profiles showed that the combination of R164S with G238S drastically reduced the extended-spectrum activity of the respective single mutants.
authors.affiliation: Laboratory of Antimicrobial Agents, Department of Microbiology, Medical School, University of Athens, M. Asias 75, Athens 11527, Greece.
authors.forename: P
authors.initials: P
authors.lastname: Giakkoupi
authors.forename: E
authors.initials: E
authors.lastname: Tzelepi
authors.forename: P T
authors.initials: PT
authors.lastname: Tassios
authors.forename: N J
authors.initials: NJ
authors.lastname: Legakis
authors.forename: L S
authors.initials: LS
authors.lastname: Tzouvelekis
mesh_terms: D019943:Amino Acid Substitution; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D016297:Mutagenesis, Site-Directed; D018440:beta-Lactam Resistance / Q000235:genetics*; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*; D047090:beta-Lactams
chemical_list: D000900:Anti-Bacterial Agents; D047090:beta-Lactams; D001618:beta-Lactamases; C034413:beta-lactamase TEM-1