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Structure of the type VI secretion system contractile sheath.

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Kudryashev Mikhail, Wang Ray Yu-Ruei, Brackmann Maximilian, Scherer Sebastian, Maier Timm, Baker David, DiMaio Frank, Stahlberg Henning, Egelman Edward H, Basler Marek,
Project Electron Microscopy of Membrane Proteins
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Original article (peer-reviewed)

Journal Cell
Volume (Issue) 160(5)
Page(s) 952 - 62
Title of proceedings Cell
DOI 10.1016/j.cell.2015.01.037

Abstract

Bacteria use rapid contraction of a long sheath of the type VI secretion system (T6SS) to deliver effectors into a target cell. Here, we present an atomic-resolution structure of a native contracted Vibrio cholerae sheath determined by cryo-electron microscopy. The sheath subunits, composed of tightly interacting proteins VipA and VipB, assemble into a six-start helix. The helix is stabilized by a core domain assembled from four β strands donated by one VipA and two VipB molecules. The fold of inner and middle layers is conserved between T6SS and phage sheaths. However, the structure of the outer layer is distinct and suggests a mechanism of interaction of the bacterial sheath with an accessory ATPase, ClpV, that facilitates multiple rounds of effector delivery. Our results provide a mechanistic insight into assembly of contractile nanomachines that bacteria and phages use to translocate macromolecules across membranes.
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