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Type: Artigo
Title: Importance of the β5−β6 Loop for the structure, catalytic efficiency and stability of carbapenem-hydrolyzing class D β-Lactamase subfamily OXA-143
Author: Antunes, Victor U.
Llontop, Edgar E.
Vasconcelos, Fernanda N. da Costa
de los Santos, Yossef Lopez
Oliveira, Ronaldo J.
Lincopan, Nilton
Farah, Chuck S.
Doucet, Nicolas
Mittermaier, Anthony
Favaro, Denize C.
Abstract: The class D beta-lactamase OXA-143 has been described as an efficient penicillinase, oxacillinase, and carbapenemase. The D224A variant, known as OXA-231, was described in 2012 as exhibiting less activity toward imipenem and increased oxacillinase activity. Additionally, the P227S mutation was reported as a case of convergent evolution for homologous enzymes. To investigate the impact of both mutations (D224A and P227S), we describe in this paper a deep investigation of the enzymatic activities of these three homologues. OXA-143(P227S) presented enhanced catalytic activity against ampicillin, oxacillins, aztreonam, and carbapenems. In addition, OXA-143(P227S) was the only member capable of hydrolyzing ceftazidime. These enhanced activities were due to a combination of a higher affinity (lower K-m) and a higher turnover number (higher k(cat)). We also determined the crystal structure of apo OXA-231. As expected, the structure of this variant is very similar to the published OXA-143 structure, except for the two M223 conformations and the absence of electron density for three solvent-exposed loop segments. Molecular dynamics calculations showed that both mutants experience higher flexibility compared to that of the wild-type form. Therefore, our results illustrate that D224A and P227S act as deleterious and positive mutations, respectively, within the evolutionary path of the OXA-143 subfamily toward a more efficient carbapenemase
Subject: Monômeros
Country: Estados Unidos
Editor: American Chemical Society
Rights: Fechado
Identifier DOI: 10.1021/acs.biochem.9b00365
Date Issue: 2019
Appears in Collections:IQ - Artigos e Outros Documentos

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