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Etude structurale et fonctionnelle de PscE:PscF:PscG, un hétérotrimère nécessaire à la biogenèse de l'aiguille de sécrétion de type III chez Pseudomonas aeruginosa

Manuelle Quinaud 1
1 LPM - Laboratoire des Protéines Membranaires
IBS - UMR 5075 - Institut de biologie structurale
Abstract : Type III secretion systems are found in several Gram-negative bacteria. These nanomachines are involved in the transport of virulence effectors directly into the cytoplasm of target cells. Pseudomonas aeruginosa, whose type III secretion needle is studied here, is the causative agent of a large number of nosocomial and chronic infections in cystic fibrosis patients. This system is composed of a base anchored in the double bacterial membrane and a hollow needle formed by a single polymerized protein (PscF in P. aeruginosa).

Within the bacterial cytoplasm, PscF requires two distinct chaperones for stabilisation before its secretion, without which the entire system is nonfunctionnal.

The 2.0A X-ray crystal structure of the PscE:PscF55-85-PscG ternary complex reveals that the C-terminus of the needle protein PscF, which is essential for needle polymerisation, is engulfed within the hydrophobic groove of the TPR-like molecule PscG. This indicates that the macromolecular scaffold necessary to stabilize the needle protein is totally distinct from chaperoned complexes between pilus- or flagellum-forming molecules.

Disruption of specific PscG:PscF interactions leads to impairement of bacterial cytotoxicity toward macrophages, indicating that this essential heterotrimer, which possesses homologs in a wide variety of pathogens, is an attractive therapeutic target for the development of novel drugs.
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https://tel.archives-ouvertes.fr/tel-00182833
Contributor : Manuelle Quinaud <>
Submitted on : Monday, October 29, 2007 - 10:06:03 AM
Last modification on : Wednesday, November 4, 2020 - 3:03:17 PM
Long-term archiving on: : Monday, April 12, 2010 - 12:53:08 AM

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  • HAL Id : tel-00182833, version 1

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Manuelle Quinaud. Etude structurale et fonctionnelle de PscE:PscF:PscG, un hétérotrimère nécessaire à la biogenèse de l'aiguille de sécrétion de type III chez Pseudomonas aeruginosa. Biochimie [q-bio.BM]. Université Joseph-Fourier - Grenoble I, 2007. Français. ⟨tel-00182833⟩

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