A refined model of the prototypical Salmonella SPI-1 T3SS basal body reveals the molecular basis for its assembly.

The T3SS injectisome is a syringe-shaped macromolecular assembly found in pathogenic Gram-negative bacteria that allows for the direct delivery of virulence effectors into host cells. It is composed of a "basal body", a lock-nut structure spanning both bacterial membranes, and a "need...

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Auteurs principaux: Julien R C Bergeron, Liam J Worrall, Nikolaos G Sgourakis, Frank DiMaio, Richard A Pfuetzner, Heather B Felise, Marija Vuckovic, Angel C Yu, Samuel I Miller, David Baker, Natalie C J Strynadka
Format: article
Langue:EN
Publié: Public Library of Science (PLoS) 2013
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Accès en ligne:https://doaj.org/article/4db4112da9e849c689b527d13a3699fa
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Résumé:The T3SS injectisome is a syringe-shaped macromolecular assembly found in pathogenic Gram-negative bacteria that allows for the direct delivery of virulence effectors into host cells. It is composed of a "basal body", a lock-nut structure spanning both bacterial membranes, and a "needle" that protrudes away from the bacterial surface. A hollow channel spans throughout the apparatus, permitting the translocation of effector proteins from the bacterial cytosol to the host plasma membrane. The basal body is composed largely of three membrane-embedded proteins that form oligomerized concentric rings. Here, we report the crystal structures of three domains of the prototypical Salmonella SPI-1 basal body, and use a new approach incorporating symmetric flexible backbone docking and EM data to produce a model for their oligomeric assembly. The obtained models, validated by biochemical and in vivo assays, reveal the molecular details of the interactions driving basal body assembly, and notably demonstrate a conserved oligomerization mechanism.