title: Type VI secretion requires a dynamic contractile phage tail-like structure.
abstract: Type VI secretion systems are bacterial virulence-associated nanomachines composed of proteins that are evolutionarily related to components of bacteriophage tails. Here we show that protein secretion by the type VI secretion system of Vibrio cholerae requires the action of a dynamic intracellular tubular structure that is structurally and functionally homologous to contractile phage tail sheath. Time-lapse fluorescence light microscopy reveals that sheaths of the type VI secretion system cycle between assembly, quick contraction, disassembly and re-assembly. Whole-cell electron cryotomography further shows that the sheaths appear as long tubular structures in either extended or contracted conformations that are connected to the inner membrane by a distinct basal structure. These data support a model in which the contraction of the type VI secretion system sheath provides the energy needed to translocate proteins out of effector cells and into adjacent target cells.
authors.affiliation: Department of Microbiology and Immunobiology, Harvard Medical School, 200 Longwood Avenue, Boston, Massachusetts 02115, USA.
authors.forename: M
authors.initials: M
authors.lastname: Basler
authors.forename: M
authors.initials: M
authors.lastname: Pilhofer
authors.forename: G P
authors.initials: GP
authors.lastname: Henderson
authors.forename: G J
authors.initials: GJ
authors.lastname: Jensen
authors.forename: J J
authors.initials: JJ
authors.lastname: Mekalanos
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure*; D058947:Bacterial Secretion Systems / Q000502:physiology*; D001435:Bacteriophages / Q000737:chemistry* / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism; D020285:Cryoelectron Microscopy; D055032:Electron Microscope Tomography; D008856:Microscopy, Fluorescence; D014734:Vibrio cholerae / Q000737:chemistry* / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems