Skip to Main content Skip to Navigation
Theses

La machinerie de sécrétion de type II Xcp de pseudomonas aeruginosa : Relations structure-fonction et interactome

Abstract : Gram-negative bacteria are characterized by a complex organization of their cell envelope composed by the inner membrane (IM) called cytoplasmic membrane, the periplasmic space containing a peptidoglycan layer and the outer membrane (OM) covered by the lipopolysaccharide matrix. Gram-negative bacteria have evolved several specialized machines called secretion systems to export their effectors from the intracellular medium to the extracellular milieu or to the host cells. Up to now, at least six secretion systems have been identified. In the opportunistic pathogen Pseudomonas aeruginosa, the type II secretion system called the Xcp secreton is the major pathway for the release of virulence factors. The Xcp secreton is a macromolecular complex composed by 12 proteins called XcpAO, XcpPC-XcpZM. This machinery is organized in 3 sub-complexes: i) the assembly platform localized in the IM implicating XcpRESFYLZM proteins ii) the OM pore composed by the oligomerization of the secretin XcpQD. The connection between the assembly platform and the secretin is performed by XcpPC anchored in the IM iii) a periplasmic pseudopilus consisting of the multimerization of the so-called major pseudopilin XcpTG. The pseudopilus is a helicoidally filament spanning the periplasmic area and pushing the substrate into the secretin pore. Four other proteins, the minor pseudopilins XcpUH-VI-WJ-XK, were found in the pseudopilus. In the present work we first focused on the study of the pseudopilus components by biochemical, biophysical and structural strategies to understand their assembly. Secondly, we investigate the protein interactome between periplasmic secreton component and secreted substrates. Thus, we revealed the presence of a quaternary complex composed by XcpUH-VI-WJ-XK located at the tip of the pseudopilus. To understand at atomic scale the regulation of the pseudopilus, we determined the structure of two components of the pseudopilus XcpTG by NMR and XcpWJ by X-ray crystallography. Using systematic protein-protein interaction studies between secreton components and purified exoproteins of Pseudomonas aeruginosa, we identified 5 proteins of the secreton able to interact with exoproteins. This interaction network allowed us to propose a model for the secretion process including the sequential steps followed by exoproteins inside the secreton to leave the cell envelop.
Keywords : these
Document type :
Theses
Complete list of metadata

Cited literature [344 references]  Display  Hide  Download

https://hal.inrae.fr/tel-02806009
Contributor : Migration Prodinra Connect in order to contact the contributor
Submitted on : Saturday, June 6, 2020 - 1:29:21 AM
Last modification on : Tuesday, October 19, 2021 - 10:58:55 PM

File

2011_These-BadreddineDouzi-CRC...
Files produced by the author(s)

Licence


Distributed under a Creative Commons Attribution 4.0 International License

Identifiers

  • HAL Id : tel-02806009, version 1
  • PRODINRA : 480653

Collections

Citation

Badreddine Douzi. La machinerie de sécrétion de type II Xcp de pseudomonas aeruginosa : Relations structure-fonction et interactome. Sciences du Vivant [q-bio]. Université de Provence, 2011. Français. ⟨tel-02806009⟩

Share

Metrics

Record views

557

Files downloads

146