Properties of mutant SHV-5 beta-lactamases constructed by substitution of isoleucine or valine for methionine at position 69.
The effect of replacement of Met-69 by Ile or Val on the properties of the extended-spectrum beta-lactamase SHV-5 was studied. Mutant enzymes were constructed by site-specific mutagenesis and expressed under isogenic conditions in Escherichia coli DH5alpha cells. Compared with SHV-5, the mutant beta-lactamases conferred lower levels of beta-lactam resistance and were less efficient in hydrolyzing ampicillin, cephalothin, and cefotaxime. The substitutions rendered SHV-5 less susceptible to inhibition by clavulanate, sulbactam, and tazobactam; however, the MICs of penicillin-inhibitor combinations remained similar, suggesting an attenuation of penicillinase activity.
Giakkoupi
P
P
Department of Bacteriology, Hellenic Pasteur Institute, Athens, Greece.
Miriagou
V
V
Gazouli
M
M
Tzelepi
E
E
Legakis
N J
NJ
Tzouvelekis
L S
LS
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D005798:Genes, Bacterial / Q000235:genetics*; D007532:Isoleucine / Q000737:chemistry; D008715:Methionine / Q000737:chemistry; D008826:Microbial Sensitivity Tests; D016297:Mutagenesis, Site-Directed; D014633:Valine / Q000737:chemistry; D018440:beta-Lactam Resistance / Q000235:genetics; D001618:beta-Lactamases / Q000737:chemistry / Q000235:genetics*
D000900:Anti-Bacterial Agents; D007532:Isoleucine; D008715:Methionine; D001618:beta-Lactamases; D014633:Valine