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J Mol Biol ; 433(19): 167150, 2021 09 17.
Artigo em Inglês | MEDLINE | ID: mdl-34271009

RESUMO

The resistance of Gram-negative bacteria to ß-lactam antibiotics stems mainly from ß-lactamase proteins that hydrolytically deactivate the ß-lactams. Of particular concern are the ß-lactamases that can deactivate a class of ß-lactams known as carbapenems. Carbapenems are among the few anti-infectives that can treat multi-drug resistant bacterial infections. Revealing the mechanisms of their deactivation by ß-lactamases is a necessary step for preserving their therapeutic value. Here, we present NMR investigations of OXA-24/40, a carbapenem-hydrolyzing Class D ß-lactamase (CHDL) expressed in the gram-negative pathogen, Acinetobacter baumannii. Using rapid data acquisition methods, we were able to study the "real-time" deactivation of the carbapenem known as doripenem by OXA-24/40. Our results indicate that OXA-24/40 has two deactivation mechanisms: canonical hydrolytic cleavage, and a distinct mechanism that produces a ß-lactone product that has weak affinity for the OXA-24/40 active site. The mechanisms issue from distinct active site environments poised either for hydrolysis or ß-lactone formation. Mutagenesis reveals that R261, a conserved active site arginine, stabilizes the active site environment enabling ß-lactone formation. Our results have implications not only for OXA-24/40, but the larger family of CHDLs now challenging clinical settings on a global scale.


Assuntos
Antibacterianos/farmacologia , Doripenem/farmacologia , beta-Lactamases/metabolismo , Acinetobacter baumannii/genética , Antibacterianos/química , Arginina/química , Arginina/genética , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Domínio Catalítico , Doripenem/química , Farmacorresistência Bacteriana Múltipla , Hidrólise , Testes de Sensibilidade Microbiana , Modelos Moleculares , Simulação de Dinâmica Molecular , Estrutura Secundária de Proteína , beta-Lactamases/química , beta-Lactamases/genética
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