Structure of a bacterial type IV secretion core complex at subnanometre resolution |
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| Authors: | Angel Rivera-Calzada Rémi Fronzes Christos G Savva Vidya Chandran Pei W Lian Toon Laeremans Els Pardon Jan Steyaert Han Remaut Gabriel Waksman Elena V Orlova |
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| Affiliation: | 1Department of Biological Sciences, Institute of Structural and Molecular Biology, UCL and Birkbeck, London, UK;2Institut Pasteur, G5 ‘biologie structural de la sécrétion bactérienne'', UMR-CNRS 3528, Paris, France;3Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium;4Department of Structural Biology, Vlaams Instituut voor Biotechnologie, Brussels, Belgium |
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| Abstract: | Type IV secretion (T4S) systems are able to transport DNAs and/or proteins through the membranes of bacteria. They form large multiprotein complexes consisting of 12 proteins termed VirB1‐11 and VirD4. VirB7, 9 and 10 assemble into a 1.07 MegaDalton membrane‐spanning core complex (CC), around which all other components assemble. This complex is made of two parts, the O‐layer inserted in the outer membrane and the I‐layer inserted in the inner membrane. While the structure of the O‐layer has been solved by X‐ray crystallography, there is no detailed structural information on the I‐layer. Using high‐resolution cryo‐electron microscopy and molecular modelling combined with biochemical approaches, we determined the I‐layer structure and located its various components in the electron density. Our results provide new structural insights on the CC, from which the essential features of T4S system mechanisms can be derived. |
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| Keywords: | core complex cryo electron microscopy pKM101 structure type 4 secretion system |
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