title: Remodelling of VipA/VipB tubules by ClpV-mediated threading is crucial for type VI protein secretion.
abstract: The recently identified type VI secretion systems (T6SS) have a crucial function in the virulence of various proteobacteria, including the human pathogen Vibrio cholerae. T6SS are encoded by a conserved gene cluster comprising approximately 15 open reading frames, mediating the appearance of Hcp and VgrG proteins in cell culture supernatants. Here, we analysed the function of the V. cholerae T6SS member ClpV, a specialized AAA+ protein. ClpV is crucial for a functional T6SS and interacts through its N-terminal domain with the VipA/VipB complex that is composed of two conserved and essential members of T6SS. Transferring ClpV substrate specificity to a distinct AAA+ protein involved in proteolysis caused degradation of VipA but not Hcp or VgrG2, suggesting that VipA rather than Hcp/VgrG2 functions as a primary ClpV substrate. Strikingly, VipA/VipB form tubular, cogwheel-like structures that are converted by a threading activity of ClpV into small complexes. ClpV-mediated remodelling of VipA/VipB tubules represents a crucial step in T6S, illuminating an unexpected role of an ATPase component in protein secretion.
authors.affiliation: Zentrum für Molekulare Biologie Heidelberg, DKFZ-ZMBH Alliance, Universität Heidelberg, Heidelberg, Germany.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Bönemann
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Pietrosiuk
authors.forename: Alexander
authors.initials: A
authors.lastname: Diemand
authors.forename: Hanswalter
authors.initials: H
authors.lastname: Zentgraf
authors.forename: Axel
authors.initials: A
authors.lastname: Mogk
mesh_terms: D000251:Adenosine Triphosphatases / Q000502:physiology*; D001426:Bacterial Proteins / Q000378:metabolism; D001692:Biological Transport; D002352:Carrier Proteins / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial; D008854:Microscopy, Electron; D018832:Molecular Chaperones / Q000378:metabolism; D005810:Multigene Family; D016366:Open Reading Frames; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D014734:Vibrio cholerae / Q000378:metabolism*; D014774:Virulence; D037521:Virulence Factors / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D018832:Molecular Chaperones; D037521:Virulence Factors; D000251:Adenosine Triphosphatases