A triple mutant in the Ω-loop of TEM-1 β-lactamase changes the substrate profile via a large conformational change and an altered general base for catalysis.

ABSTRACT: β-Lactamases are bacterial enzymes that hydrolyze β-lactam antibiotics. TEM-1 is a prevalent plasmid-encoded β-lactamase in Gram-negative bacteria that efficiently catalyzes the hydrolysis of penicillins and early cephalosporins but not oxyimino-cephalosporins. A previous random mutagenesis study identified a W165Y/E166Y/P167G triple mutant that displays greatly altered substrate specificity with increased activity for the oxyimino-cephalosporin, ceftazidime, and decreased activity toward all other β-lactams tested. Surprisingly, this mutant lacks the conserved Glu-166 residue critical for enzyme function. Ceftazidime contains a large, bulky side chain that does not fit optimally in the wild-type TEM-1 active site. Therefore, it was hypothesized that the substitutions in the mutant expand

SUBMITTER: Stojanoski V 

PROVIDER: S-EPMC4400348 | biostudies-literature | 2015 Apr

REPOSITORIES: biostudies-literature