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In vivo structure of the Legionella type II secretion system by electron cryotomography

Ghosal, Debnath and Kim, Ki Woo and Zheng, Huaixin and Kaplan, Mohammed and Vogel, Joseph P. and Cianciotto, Nicholas P. and Jensen, Grant J. (2019) In vivo structure of the Legionella type II secretion system by electron cryotomography. . (Unpublished)

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The type II secretion system (T2SS) is a multi-protein envelope-spanning assembly that translocates a wide range of virulence factors, enzymes and effectors through the outer membrane (OM) of many Gram-negative bacteria. Here, using electron cryotomography and subtomogram averaging methods, we present the first in situ structure of an intact T2SS, imaged within the human pathogen Legionella pneumophila. Although the T2SS has only limited sequence and component homology with the evolutionarily-related Type IV pilus (T4P) system, we show that their overall architectures are remarkably similar. Despite similarities, there are also differences, including for instance that the T2SS-ATPase complex is usually present but disengaged from the inner membrane, the T2SS has a much longer periplasmic vestibule, and it has a short-lived flexible pseudopilus. Placing atomic models of the components into our ECT map produced a complete architectural model of the intact T2SS that provides new insights into the structure and function of its components, its position within the cell envelope, and the interactions between its different subcomplexes. Overall, these structural results strongly support the piston model for substrate extrusion.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Ghosal, Debnath0000-0002-2227-0330
Kim, Ki Woo0000-0002-7010-0336
Vogel, Joseph P.0000-0002-8054-5021
Jensen, Grant J.0000-0003-1556-4864
Additional Information:The copyright holder for this preprint is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. All rights reserved. No reuse allowed without permission. bioRxiv preprint first posted online Jan. 19, 2019. This work was supported by NIH grants AI127401 to G.J.J. and AI043987 to N.P.C. ECT data were recorded at the Beckman Institute Resource Center for Transmission Electron Microcopy at Caltech and the cryo-EM facility at Janelia Research Campus. We thank Dr. Davi Ortega for helpful discussions. M. K. is supported by a postdoctoral Rubicon fellowship from De Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO). Data availability: The subtomogram average of the L. pneumophila T2SS has been deposited in the Electron Microscopy Data Bank under the following accession codes: XXXX (wild-type aligned on the OM part); EMD-XXX (wild-type, aligned on the IM part).
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Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)UNSPECIFIED
Record Number:CaltechAUTHORS:20190123-125316052
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Official Citation:In vivo structure of the Legionella type II secretion system by electron cryotomography. Debnath Ghosal, Ki Woo Kim, Huaixin Zheng, Mohammed Kaplan, Joseph P. Vogel, Nicholas P. Cianciotto, Grant J Jensen. bioRxiv 525063; doi:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92431
Deposited By: Tony Diaz
Deposited On:23 Jan 2019 22:20
Last Modified:22 Apr 2019 23:37

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