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Structure of Enterococcus faecium l , d -Transpeptidase Acylated by Ertapenem Provides Insight into the Inactivation Mechanism

2013; American Chemical Society; Volume: 8; Issue: 6 Linguagem: Inglês

10.1021/cb4001603

1554-8937

Lauriane Lecoq, Vincent Dubée, Sébastien Triboulet, Catherine Bougault, Jean‐Emmanuel Hugonnet, Michel Arthur, Jean‐Pierre Simorre,

Antibiotics Pharmacokinetics and Efficacy

The maintenance of bacterial cell shape and integrity is largely attributed to peptidoglycan, a biopolymer highly cross-linked through d,d-transpeptidation. Peptidoglycan cross-linking is catalyzed by penicillin-binding proteins (PBPs) that are the essential target of β-lactam antibiotics. PBPs are functionally replaced by l,d-transpeptidases (Ldts) in ampicillin-resistant mutants of Enterococcus faecium and in wild-type Mycobacterium tuberculosis. Ldts are inhibited in vivo by a single class of β-lactams, the carbapenems, which act as a suicide substrate. We present here the first structure of a carbapenem-acylated l,d-transpeptidase, E. faecium Ldtfm acylated by ertapenem, which revealed key contacts between the carbapenem core and residues of the catalytic cavity of the enzyme. Significant reorganization of the antibiotic conformation occurs upon enzyme acylation. These results, together with the analysis of protein-to-carbapenem proton transfers, provide new insights into the mechanism of Ldt acylation by carbapenems.