Wang, JingBrackmann, MaximilianCastano-Diez, DanielKudryashev, MikhailGoldie, Kenneth N.Maier, TimmStahlberg, HenningBasler, Marek2020-02-132020-02-132020-02-132017-09-2510.1038/s41564-017-0020-7https://infoscience.epfl.ch/handle/20.500.14299/165461The bacterial type VI secretion system (T6SS) uses contraction of a long sheath to quickly thrust a tube with associated effectors across membranes of eukaryotic and bacterial cells(1-5). Only limited structural information is available about the inherently unstable precontraction state of the T6SS. Here, we obtain a 3.7 angstrom resolution structure of a non-contractile sheath-tube complex using cryo-electron microscopy and show that it resembles the extended T6SS inside Vibrio cholerae cells. We build a pseudo-atomic model of the complete sheath-tube assembly, which provides a mechanistic understanding of coupling sheath contraction with pushing and rotating the inner tube for efficient target membrane penetration. Our data further show that sheath contraction exposes a buried recognition domain to specifically trigger the disassembly and recycling of the T6SS sheath by the cognate ATP-dependent unfoldase ClpV.text::journal::journal article::research article