Characterization of Pseudomonas aeruginosa L,D-transpeptidases and evaluation of their role in peptidoglycan adaptation to biofilm growth - Centre de recherche des Cordeliers Accéder directement au contenu
Pré-Publication, Document De Travail Année : 2023

Characterization of Pseudomonas aeruginosa L,D-transpeptidases and evaluation of their role in peptidoglycan adaptation to biofilm growth

Résumé

Peptidoglycan is an essential component of the bacterial cell envelope that sustains the turgor pressure of the cytoplasm, determines cell shape, and acts as a scaffold for the anchoring of envelope polymers such as lipoproteins. The final cross-linking step of peptidoglycan polymerization is performed by classical D,D-transpeptidases belonging to the penicillin-binding protein (PBP) family and by L,D-transpeptidases (LDTs), which are dispensable for growth in most bacterial species and whose physiological functions remain elusive. In this study, we investigated the contribution of LDTs to cell envelope synthesis in Pseudomonas aeruginosa grown in planktonic and biofilm conditions. We first assigned a function to each of the three P. aeruginosa LDTs by gene inactivation in P. aeruginosa, heterospecific gene expression in Escherichia coli, and, for one of them, direct determination of its enzymatic activity. We found that the three P. aeruginosa LDTs catalyze peptidoglycan cross-linking (LdtPae1), the anchoring of lipoprotein OprI to the peptidoglycan (LdtPae2), and the hydrolysis of the resulting peptidoglycan-OprI amide bond (LdtPae3). Construction of a phylogram revealed that LDTs performing each of these three functions in various species cannot be assigned to evolutionary distinct lineages, in contrast to what has been observed with PBPs. We showed that biofilm, but not planktonic, bacteria displayed an increase proportion of peptidoglycan cross-links formed by LdtPae1 and a higher extent of OprI anchoring to peptidoglycan, which is controlled by LdtPae2 and LdtPae3. Consistently, deletion of each of the ldt gene impaired biofilm formation and potentiated the bactericidal activity of ethylenediaminetetraacetic acid (EDTA). These results indicate that LDTs contribute to the stabilization of the bacterial cell envelope and to the adaptation of peptidoglycan metabolism to growth in biofilm.
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Dates et versions

hal-04112100 , version 1 (31-05-2023)
hal-04112100 , version 2 (06-06-2023)

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Paternité

Identifiants

  • HAL Id : hal-04112100 , version 1

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Inès Hugonneau-Beaufet, Jean-Philippe Barnier, Stanislas Thiriet-Rupert, Sylvie Letoffe, Jean-Luc Mainardi, et al.. Characterization of Pseudomonas aeruginosa L,D-transpeptidases and evaluation of their role in peptidoglycan adaptation to biofilm growth. 2023. ⟨hal-04112100v1⟩
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