title: Structural biology of type VI secretion systems.
abstract: Type VI secretion systems (T6SSs) are transenvelope complexes specialized in the transport of proteins or domains directly into target cells. These systems are versatile as they can target either eukaryotic host cells and therefore modulate the bacteria-host interaction and pathogenesis or bacterial cells and therefore facilitate access to a specific niche. These molecular machines comprise at least 13 proteins. Although recent years have witnessed advances in the role and function of these secretion systems, little is known about how these complexes assemble in the cell envelope. Interestingly, the current information converges to the idea that T6SSs are composed of two subassemblies, one resembling the contractile bacteriophage tail, whereas the other subunits are embedded in the inner and outer membranes and anchor the bacteriophage-like structure to the cell envelope. In this review, we summarize recent structural information on individual T6SS components emphasizing the fact that T6SSs are composite systems, adapting subunits from various origins.
authors.affiliation: CNRS, Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UMR 7255, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France. cascales@imm.cnrs.fr
authors.forename: Eric
authors.initials: E
authors.lastname: Cascales
authors.forename: Christian
authors.initials: C
authors.lastname: Cambillau
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D058947:Bacterial Secretion Systems; D002462:Cell Membrane / Q000737:chemistry; D004926:Escherichia coli / Q000737:chemistry; D029968:Escherichia coli Proteins / Q000737:chemistry; D055666:Lipopeptides / Q000737:chemistry; D008565:Membrane Proteins / Q000737:chemistry; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry; D046912:Multiprotein Complexes / Q000737:chemistry*; D019897:Periplasm / Q000737:chemistry; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D021381:Protein Transport
chemical_list: D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems; D029968:Escherichia coli Proteins; D055666:Lipopeptides; D008565:Membrane Proteins; D018832:Molecular Chaperones; D046912:Multiprotein Complexes; C572322:TssJ protein, E coli