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Structure of the outer membrane complex of a type IV secretion system

Chandran, V; Fronzes, R; Duquerroy, S; Cronin, N; Navaza, J; Waksman, G; (2009) Structure of the outer membrane complex of a type IV secretion system. NATURE , 462 (7276) 1011 - U66. 10.1038/nature08588. Gold open access

Abstract

Type IV secretion systems are secretion nanomachines spanning the two membranes of Gram-negative bacteria. Three proteins, VirB7, VirB9 and VirB10, assemble into a 1.05 megadalton (MDa) core spanning the inner and outer membranes. This core consists of 14 copies of each of the proteins and forms two layers, the I and O layers, inserting in the inner and outer membrane, respectively. Here we present the crystal structure of a similar to 0.6 MDa outer-membrane complex containing the entire O layer. This structure is the largest determined for an outer-membrane channel and is unprecedented in being composed of three proteins. Unexpectedly, this structure identifies VirB10 as the outer-membrane channel with a unique hydrophobic double-helical transmembrane region. This structure establishes VirB10 as the only known protein crossing both membranes of Gram-negative bacteria. Comparison of the cryo-electron microscopy (cryo-EM) and crystallographic structures points to conformational changes regulating channel opening and closing.

Type: Article
Title: Structure of the outer membrane complex of a type IV secretion system
Open access status: An open access publication
DOI: 10.1038/nature08588
Publisher version: http://ukpmc.ac.uk/abstract/MED/19946264
Keywords: AGROBACTERIUM VIRB10, HELICOBACTER-PYLORI, PROTEIN, DNA, BIOGENESIS, SOFTWARE, BACTERIA, MACHINERY
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences > Structural and Molecular Biology
URI: http://discovery.ucl.ac.uk/id/eprint/168761
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