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Elife. 2018 Oct 3;7. pii: e39514. doi: 10.7554/eLife.39514.

Visualization of the type III secretion mediated Salmonella-host cell interface using cryo-electron tomography.

Author information

1
Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, United States.
2
Microbial Sciences Institute, Yale University School of Medicine, New Haven, United States.
3
Department of Neurobiology and Anatomy, McGovern Medical School, The University of Texas Health Science Center at Houston, Texas, United States.
4
Department of Microbiology and Molecular Genetics, McGovern Medical School, The University of Texas Health Science Center at Houston, Texas, United States.
5
Department of Pathology and Laboratory Medicine, McGovern Medical School, The University of Texas Health Science Center at Houston, Texas, 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.

KEYWORDS:

Macromolecular assembly; S. enterica; bacterial pathogenesis; host-pathogen interaction; infectious disease; membrane remodeling; microbiology; protein secretion; serovar typhie

PMID:
30281019
PMCID:
PMC6175578
DOI:
10.7554/eLife.39514
[Indexed for MEDLINE]
Free PMC Article

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