Activation of the l,d‐transpeptidation peptidoglycan cross‐linking pathway by a metallo‐d,d‐carboxypeptidase in Enterococcus faecium |
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| Authors: | Emmanuelle Sacco Jean‐Emmanuel Hugonnet Nathalie Josseaume Julie Cremniter Lionel Dubost Arul Marie Delphine Patin Didier Blanot Louis B Rice Jean‐Luc Mainardi Michel Arthur |
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| Institution: | 1. Centre de Recherche des Cordeliers, LRMA, Equipe 12, Université Pierre et Marie Curie – Paris6, UMR S 872, Paris, F‐75006 France.;2. Université Paris Descartes, UMR S 872, Paris, F‐75006 France.;3. INSERM, U872, Paris, F‐75006 France.;4. These authors contributed equally to the work.;5. Muséum National d'Histoire Naturelle, Plateforme de Spectrométrie de Masse et de Protéomique du Muséum, Département Régulation Développement et Diversité Moléculaire, Paris, F‐75005 France.;6. Molécules de Communication et Adaptation des Micro‐Organismes, FRE 3206 CNRS, Paris, F‐75005 France.;7. Laboratoire des Enveloppes Bactériennes et Antibiotiques, Institut de Biochimie et Biophysique Moléculaire et Cellulaire, UMR 8619 CNRS, Univ Paris‐Sud, 91405 Orsay, France.;8. Medical and Research Services, Louis Stokes Cleveland VA Medical Center, Cleveland, OH 44106, USA.;9. AP‐HP, H?pital Européen Georges Pompidou, Paris, F‐75015 France. |
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| Abstract: | Bypass of the penicillin‐binding proteins by an l ,d ‐transpeptidase (Ldtfm) confers cross‐resistance to β‐lactam and glycopeptide antibiotics in mutants of Enterococcus faecium selected in vitro. Ldtfm is produced by the parental strain D344S although it insignificantly contributes to peptidoglycan cross‐linking as pentapeptide stems cannot be used as acyl donors by this enzyme. Here we show that production of the tetrapeptide substrate of Ldtfm is controlled by a two‐component regulatory system (DdcRS) and a metallo‐d ,d ‐carboxypeptidase (DdcY). The locus was silent in D344S and its activation was due to amino acid substitutions in DdcS or DdcR that led to production of DdcY and hydrolysis of the C‐terminal d ‐Ala residue of the cytoplasmic peptidoglycan precursor UDP‐MurNAc‐pentapeptide. The T161A and T161M substitutions affected a position of DdcS known to be essential for the phosphatase activity of related sensor kinases. Complete elimination of UDP‐MurNAc‐pentapeptide, which was required specifically for resistance to glycopeptides, involved substitutions in DdcY that increased the catalytic efficiency of the enzyme (E127K) and affected its interaction with the cell envelope (I14N). The ddc locus displays striking similarities with portions of the van vancomycin resistance gene clusters, suggesting possible routes of emergence of cross‐resistance to glycopeptides and β‐lactams in natural conditions. |
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