6nz8

Publication Abstract from PubMed

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 Km) and a higher turnover number (higher kcat). 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.

Importance of the beta5-beta6 Loop for the Structure, Catalytic Efficiency, and Stability of Carbapenem-Hydrolyzing Class D beta-Lactamase Subfamily OXA-143.,Antunes VU, Llontop EE, Vasconcelos FNDC, Lopez de Los Santos Y, Oliveira RJ, Lincopan N, Farah CS, Doucet N, Mittermaier A, Favaro DC Biochemistry. 2019 Aug 27;58(34):3604-3616. doi: 10.1021/acs.biochem.9b00365., Epub 2019 Aug 15. PMID:31355630^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.