In situ and high-resolution Cryo-EM structure of the Type VI secretion membrane complex - Aix-Marseille Université Access content directly
Journal Articles EMBO Journal Year : 2019

In situ and high-resolution Cryo-EM structure of the Type VI secretion membrane complex

Abstract

Bacteria have evolved macromolecular machineries that secrete effectors and toxins to survive and thrive in diverse environments. The type VI secretion system (T6SS) is a contractile machine that is related to Myoviridae phages. It is composed of a phage tail-like structure inserted in the bacterial cell envelope by a membrane complex (MC) comprising the TssJ, TssL and TssM proteins. We previously reported the low-resolution negative-stain electron microscopy structure of the enteroaggregative Escherichia coli MC, and proposed a rotational 5-fold symmetry with a TssJ:TssL:TssM stoichiometry of 2:2:2. Here, cryo-electron tomography analyses of the T6SS MC confirm the 5-fold symmetry in situ and identify the regions of the structure that insert into the bacterial membranes. A high-resolution model obtained by single particle cryo-electron microscopy highlights new features: five additional copies of TssJ, yielding a TssJ:TssL:TssM stoichiometry of 3:2:2, an 11-residue loop in TssM, protruding inside the lumen of the MC and constituting a functionally important periplasmic gate, and hinge regions. Based on these data, we propose an updated model on T6SS structure, assembly and function.
Fichier principal
Vignette du fichier
Rapisarda-FINAL.pdf (34.93 Mo) Télécharger le fichier
Origin : Files produced by the author(s)
Loading...

Dates and versions

hal-02342926 , version 1 (01-11-2019)

Licence

Attribution - NonCommercial - NoDerivatives

Identifiers

Cite

Chiara Rapisarda, Yassine Cherrak, Romain Kooger, Victoria Schmidt, Riccardo Pellarin, et al.. In situ and high-resolution Cryo-EM structure of the Type VI secretion membrane complex. EMBO Journal, 2019, 38 (10), ⟨10.15252/embj.2018100886⟩. ⟨hal-02342926⟩
91 View
48 Download

Altmetric

Share

Gmail Facebook X LinkedIn More