INVESTIGADORES
RUGGIERO Melina
artículos
Título:
Mutations at Arg220 and Thr237 in PER-2 b-lactamase: impact on conformation, activity and susceptibility to inhibitors
Autor/es:
M. RUGGIERO; L. CURTO; F. BRUNETTI; E. SAUVAGE; M. GALLENI; P. POWER; G. GUTKIND
Revista:
ANTIMICROBIAL AGENTS AND CHEMOTHERAPY
Editorial:
AMER SOC MICROBIOLOGY
Referencias:
Lugar: Washington; Año: 2017
ISSN:
0066-4804
Resumen:
PER-2 accounts for up to 10% of oxyimino-cephalosporin resistance in Klebsiella pneumoniae and Escherichia coli in Argentina, and hydrolyzes both cefotaxime and ceftazidime with high catalytic efficiencies (kcat/Km). Through crystallographic analyses, we recently proposed the existence of a hydrogen-bond network connecting Ser70-Gln69-oxyanion water-Thr237-Arg220 that might be important for the activity and inhibition of the enzyme. Mutations at Arg244 in most class A β-lactamases (as TEM and SHV) reduce susceptibility to mechanism-based inactivators, and Arg220 in PER β-lactamases is equivalent to Arg244. Alterations in the hydrogen bond network of the active site in PER-2, through modifications in key residues such as Arg220 and (to a much lesser extent) Thr237, dramatically impact the overall susceptibility to inactivation, with up to ~300 and 500-fold reduction in the kinact/KI values for clavulanic acid and tazobactam, respectively. Hydrolysis on cephalosporins and aztreonam was also affected although in different extents compared to wild-type PER-2; for cefepime, only Arg220Gly mutation resulted in a strong reduction in the catalytic efficiency. Mutations at Arg220 entail modifications in the catalytic activity of PER-2, and probably local perturbations in the protein, but not global conformational changes. Therefore, the apparent structural stability of the mutants suggests that these enzymes could be possibly selected in vivo.