Visualization of the type III secretion mediated Salmonella-host cell interface using cryo-electron tomography
- Yale University School of Medicine, United States
- The University of Texas Health Science Center at Houston, United States
Abstract
Many important gram-negative bacterial pathogens use highly sophisticated type III protein secretion systems (T3SSs) to establish complex host-pathogen interactions. Bacterial-host cell contact triggers the activation of the T3SS and the subsequent insertion of a translocon pore into the target cell membrane, which serves as a conduit for the passage of effector proteins. Therefore the initial interaction between T3SS-bearing bacteria and host cells is the critical step in the deployment of the protein secretion machine, yet this process remains poorly understood. Here, we use high-throughput cryo-electron tomography (cryo-ET) to visualize the T3SS-mediated Salmonella-host cell interface. Our analysis reveals the intact translocon at an unprecedented level of resolution, its deployment in the host cell membrane, and the establishment of an intimate association between the bacteria and the target cells, which is essential for effector translocation. Our studies provide critical data supporting the long postulated direct injection model for effector translocation.
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All data generated or analysed during this study are included in the manuscript and supporting files.
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Funding
National Institute of Allergy and Infectious Diseases (AI030492)
- Jorge E Galán
National Institute of General Medical Sciences (GM107629)
- Jun Liu
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2018, Park et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Visualization of the type III secretion mediated Salmonella-host cell interface using cryo-electron tomography
eLife 7:e39514.
https://doi.org/10.7554/eLife.39514
