1. Microbiology and Infectious Disease

Cryo-EM reveals species-specific components within the Helicobacter pylori Cag type IV secretion system core complex

  1. Michael J Sheedlo
  2. Jeong Min Chung
  3. Neha Sawhney
  4. Clarissa L Durie
  5. Timothy L Cover  Is a corresponding author
  6. Melanie D Ohi  Is a corresponding author
  7. D Borden Lacy  Is a corresponding author
  1. Vanderbilt University Medical Center, United States
  2. University of Michigan, United States
  3. Vanderbilt University School of Medicine, United States
  4. University Of Michigan, United States
https://doi.org/10.7554/eLife.59495
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Cite this article
  1. Michael J Sheedlo
  2. Jeong Min Chung
  3. Neha Sawhney
  4. Clarissa L Durie
  5. Timothy L Cover
  6. Melanie D Ohi
  7. D Borden Lacy
(2020)
Cryo-EM reveals species-specific components within the Helicobacter pylori Cag type IV secretion system core complex
eLife 9:e59495.
https://doi.org/10.7554/eLife.59495
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Abstract

The pathogenesis of Helicobacter pylori-associated gastric cancer is dependent on delivery of CagA into host cells through a type IV secretion system (T4SS). The H. pylori Cag T4SS includes a large membrane-spanning core complex containing 5 proteins, organized into an outer membrane cap (OMC), a periplasmic ring (PR) and a stalk. Here, we report cryo-EM reconstructions of a core complex lacking Cag3 and an improved map of the wild-type complex. We define the structures of two unique species-specific components (Cag3 and CagM) and show that Cag3 is structurally similar to CagT. Unexpectedly, components of the OMC are organized in a 1:1:2:2:5 molar ratio (CagY:CagX:CagT:CagM:Cag3). CagX and CagY are components of both the OMC and the PR and bridge the symmetry mismatch between these regions. These results reveal that assembly of the H. pylori T4SS core complex is dependent on incorporation of interwoven species-specific components.

Data availability

All cryo-EM data included in this manuscript are available through the Electron Microscopy Data Bank (EMD-20021, EMD-22081, EMD-22076, and EMD-22077). All models that were constructed from these data are available via the Protein Data Bank (PDB 6X6S, 6X6J, 6X6K, and 6X6L).

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Article and author information

Author details

  1. Michael J Sheedlo

    Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-3185-1727

  2. Jeong Min Chung

    Life Sciences Institute, University of Michigan, Ann Arbor, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-4285-8764

  3. Neha Sawhney

    Department of Medicine, Vanderbilt University School of Medicine, Nasvhille, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-4943-1018

  4. Clarissa L Durie

    Life Sciences Institute, University Of Michigan, Ann Arbor, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-4027-4386

  5. Timothy L Cover

    Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, United States
    For correspondence
    timothy.l.cover@vumc.org
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-8503-002X

  6. Melanie D Ohi

    Life Sciences Institute, University of Michigan, Ann Arbor, United States
    For correspondence
    mohi@umich.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-1750-4793

  7. D Borden Lacy

    Pathology, Microbiology and Immunology; Biochemistry, Vanderbilt University Medical Center, Nashville, United States
    For correspondence
    borden.lacy@vanderbilt.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-2273-8121

Funding

National Institute of Allergy and Infectious Diseases (AI118932)

  • Timothy L Cover
  • Melanie D Ohi
  • D Borden Lacy

National Institute of Allergy and Infectious Diseases (AI039657)

  • Timothy L Cover

National Cancer Institute (CA116087)

  • Timothy L Cover

National Institute of General Medical Sciences (GM103310)

  • Melanie D Ohi

National Institute of Diabetes and Digestive and Kidney Diseases (2T32DK007673)

  • Michael J Sheedlo

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Copyright

This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.

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  1. Michael J Sheedlo
  2. Jeong Min Chung
  3. Neha Sawhney
  4. Clarissa L Durie
  5. Timothy L Cover
  6. Melanie D Ohi
  7. D Borden Lacy
(2020)
Cryo-EM reveals species-specific components within the Helicobacter pylori Cag type IV secretion system core complex
eLife 9:e59495.
https://doi.org/10.7554/eLife.59495

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https://doi.org/10.7554/eLife.59495

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Further reading

    1. Microbiology and Infectious Disease
    2. Structural Biology and Molecular Biophysics

    Structural analysis of the Legionella pneumophila Dot/Icm type IV secretion system core complex

    Clarissa L Durie, Michael J Sheedlo ... Melanie D Ohi
    Research Article Updated

    Legionella pneumophila is an opportunistic pathogen that causes the potentially fatal pneumonia Legionnaires’ Disease. This infection and subsequent pathology require the Dot/Icm Type IV Secretion System (T4SS) to deliver effector proteins into host cells. Compared to prototypical T4SSs, the Dot/Icm assembly is much larger, containing ~27 different components including a core complex reported to be composed of five proteins: DotC, DotD, DotF, DotG, and DotH. Using single particle cryo-electron microscopy (cryo-EM), we report reconstructions of the core complex of the Dot/Icm T4SS that includes a symmetry mismatch between distinct structural features of the outer membrane cap (OMC) and periplasmic ring (PR). We present models of known core complex proteins, DotC, DotD, and DotH, and two structurally similar proteins within the core complex, DotK and Lpg0657. This analysis reveals the stoichiometry and contact interfaces between the key proteins of the Dot/Icm T4SS core complex and provides a framework for understanding a complex molecular machine.