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Peptides antimicrobiens des entérobactéries
Etude de la voie de maturation et du mécanisme d'import de la microcine J25, peptide antimicrobien inhibiteur de l'ARN polymérase

Abstract : Microcin J25 (MccJ25) is a gene-encoded peptide naturally secreted by Escherichia coli AY25. Its potent antibacterial activity results from the inhibition of bacterial RNA polymerase. It exhibits a lasso-type three-dimensional structure, which results from the cleavage of its inactive precursor, McjA, and athe formation of a Gly1-Glu8 amide bond. We showed in vivo and in vitro that MccJ25 utilizes the bacterial iron-siderophore transporter FhuA for uptake into bacteria. MccJ25 binds to FhuA with a Kd of 1.2 µM and a 2:1 stoichiometry. The Val11-Pro16 beta hairpin region of the MccJ25 lasso structure was shown to be required for this recognition step. We have then studied MccJ25 biosynthetic pathway. Gene inactivation and complementation assays showed that two enzymes, namely McjB and McjC, which are encoded by the microcin gene cluster, are required for the microcin maturation process. In vitro, McjB and McjC were shown to be sufficient to achieve the conversion of McjA into mature MccJ25, all proteins being obtained by recombinant expression in E. coli. From sequence similarity studies, we propose that McjB is responsible for the cleavage of McjA and that McjC is in charge of the Gly1-Glu8 bond formation.
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https://tel.archives-ouvertes.fr/tel-00193192
Contributor : Sophie Duquesne <>
Submitted on : Saturday, December 1, 2007 - 7:31:29 PM
Last modification on : Monday, March 29, 2021 - 4:46:03 PM
Long-term archiving on: : Friday, November 25, 2016 - 6:13:12 PM

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  • HAL Id : tel-00193192, version 1

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Sophie Duquesne. Peptides antimicrobiens des entérobactéries
Etude de la voie de maturation et du mécanisme d'import de la microcine J25, peptide antimicrobien inhibiteur de l'ARN polymérase. Biochimie [q-bio.BM]. Université Pierre et Marie Curie - Paris VI, 2007. Français. ⟨tel-00193192⟩

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