Substitutions in PBP2b from β-Lactam-resistant Streptococcus pneumoniae Have Different Effects on Enzymatic Activity and Drug Reactivity. - Université Grenoble Alpes Accéder directement au contenu
Article Dans Une Revue Journal of Biological Chemistry Année : 2017

Substitutions in PBP2b from β-Lactam-resistant Streptococcus pneumoniae Have Different Effects on Enzymatic Activity and Drug Reactivity.

Résumé

Pneumococcus resists β-lactams by expressing variants of its target enzymes, the penicillin-binding proteins (PBPs), with many amino acid substitutions. Up to 10% of the sequence can be modified. These altered PBPs have a much reduced reactivity with the drugs but retain their physiological activity of cross-linking the peptidoglycan, the major constituent of the bacterial cell wall. However, because β-lactams are chemical and structural mimics of the natural substrate, resistance mediated by altered PBPs raises the following paradox: how PBPs that react poorly with the drugs maintain a sufficient level of activity with the physiological substrate. This question is addressed for the first time in this study, which compares the peptidoglycan cross-linking activity of PBP2b from susceptible and resistant strains with their inhibition by different β-lactams. Unexpectedly, the enzymatic activity of the variants did not correlate with their antibiotic reactivity. This finding indicates that some of the numerous amino acid substitutions were selected to restore a viable level of enzymatic activity by a compensatory molecular mechanism.

Dates et versions

hal-01497668 , version 1 (29-03-2017)

Identifiants

Citer

Philippe Calvez, Eefjan Breukink, David I Roper, Mélanie Dib, Carlos Contreras-Martel, et al.. Substitutions in PBP2b from β-Lactam-resistant Streptococcus pneumoniae Have Different Effects on Enzymatic Activity and Drug Reactivity.. Journal of Biological Chemistry, 2017, 292 (7), pp.2854-2865. ⟨10.1074/jbc.M116.764696⟩. ⟨hal-01497668⟩
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