Architecture and Assembly of the Type VI Secretion System

Biochim Biophys Acta. 2014 Aug;1843(8):1664-73. doi: 10.1016/j.bbamcr.2014.03.018. Epub 2014 Mar 26.

Abstract

The Type VI secretion system (T6SS) delivers protein effectors to diverse cell types including prokaryotic and eukaryotic cells, therefore it participates in inter-bacterial competition and pathogenesis. The T6SS is constituted of an envelope-spanning complex anchoring a cytoplasmic tubular edifice. This tubular structure is evolutionarily, functionally and structurally related to the tail of contractile phages. It is composed of an inner tube tipped by a spike complex, and engulfed within a sheath-like structure. This structure assembles onto a platform called "baseplate" that is connected to the membrane sub-complex. The T6SS functions as a nano-crossbow: upon contraction of the sheath, the inner tube is propelled towards the target cell, allowing effector delivery. This review focuses on the architecture and biogenesis of this fascinating secretion machine, highlighting recent advances regarding the assembly of the membrane or tail complexes. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey.

Keywords: Assembly platform; Bacteriophage; Baseplate; Hcp; Inter-bacterial interactions; Membrane complex; Microbial communities; Protein transport; Secretion system; Tail; VgrG.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Bacteria / chemistry
  • Bacteria / pathogenicity*
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / metabolism*
  • Bacterial Secretion Systems / genetics*
  • Bacteriophages / chemistry
  • Bacteriophages / metabolism
  • Cell Membrane / chemistry
  • Cell Membrane / metabolism
  • Cytoplasm / metabolism
  • Eukaryotic Cells / metabolism
  • Prokaryotic Cells / metabolism
  • Protein Transport / genetics*

Substances

  • Bacterial Proteins
  • Bacterial Secretion Systems