1. Microbiology and Infectious Disease
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Cryo-EM reveals new species-specific proteins and symmetry elements in the Legionella pneumophila Dot/Icm T4SS

  1. Michael J Sheedlo
  2. Clarissa L Durie
  3. Jeong Min Chung
  4. Louise Chang
  5. Jacquelyn Roberts
  6. Michele Swanson
  7. Dana Borden Lacy
  8. Melanie D Ohi  Is a corresponding author
  1. Vanderbilt University Medical Center, United States
  2. University Of Michigan, United States
  3. University of Michigan, United States
  4. Vanderbilt University School of Medicine, United States
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Cite this article as: eLife 2021;10:e70427 doi: 10.7554/eLife.70427

Abstract

Legionella pneumophila is an opportunistic pathogen that causes the potentially fatal pneumonia known as Legionnaires' Disease. The pathology associated with infection depends on bacterial delivery of effector proteins into the host via the membrane spanning Dot/Icm type IV secretion system (T4SS). We have determined sub-3.0 Å resolution maps of the Dot/Icm T4SS core complex by single particle cryo-EM. The high-resolution structural analysis has allowed us to identify proteins encoded outside the Dot/Icm genetic locus that contribute to the core T4SS structure. We can also now define two distinct areas of symmetry mismatch, one that connects the C18 periplasmic ring (PR) and the C13 outer membrane cap (OMC) and one that connects the C13 OMC with a 16-fold symmetric dome. Unexpectedly the connection between the PR and OMC is DotH, with five copies sandwiched between the OMC and PR to accommodate the symmetry mismatch. Finally, we observe multiple conformations in the reconstructions that indicate flexibility within the structure.

Data availability

All models and maps have been uploaded to the PDB and the EMDB under accession numbers: PDB 7MUD (EMDB 24005), PDB 7MUE (EMDB 24006), PDB 7MUC (EMDB 24004), PDB 7MUQ (EMDB 24018), PDB 7MUS (EMDB 24020), PDB 7MUV (EMDB 24023), PDB 7MUW (EMDB 24024), PDB 7MUY (EMDB 24026)

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Author details

  1. Michael J Sheedlo

    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. 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
  3. 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
  4. Louise Chang

    Life Sciences Institute, University of Michigan, Ann Arbor, United States
    Competing interests
    The authors declare that no competing interests exist.
  5. Jacquelyn Roberts

    Life Sciences Institute, University Of Michigan, Ann Arbor, United States
    Competing interests
    The authors declare that no competing interests exist.
  6. Michele Swanson

    Department of Microbiology & Immunology, 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:" 0000-0003-2542-0266
  7. Dana Borden Lacy

    Department of Pathology, Microbiology, and Immunology, 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:" 0000-0003-2273-8121
  8. 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

Funding

National Institute of Allergy and Infectious Diseases (R01AI118932)

  • Jeong Min Chung
  • Jacquelyn Roberts
  • Dana Borden Lacy
  • Melanie D Ohi

National Institute of Allergy and Infectious Diseases (R21AI6465)

  • Michele Swanson
  • Melanie D Ohi

National Science Foundation

  • Jacquelyn Roberts

National Institute of Allergy and Infectious Diseases (F32 AI150027)

  • Clarissa L Durie

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

  • Michael J Sheedlo

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

Reviewing Editor

  1. Edward H Egelman, University of Virginia, United States

Publication history

  1. Received: May 16, 2021
  2. Preprint posted: June 18, 2021 (view preprint)
  3. Accepted: September 14, 2021
  4. Accepted Manuscript published: September 14, 2021 (version 1)
  5. Version of Record published: October 1, 2021 (version 2)

Copyright

© 2021, Sheedlo 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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    Early identification of severe dengue patients is important regarding patient management and resource allocation. We investigated the association of 10 biomarkers (VCAM-1, SDC-1, Ang-2, IL-8, IP-10, IL-1RA, sCD163, sTREM-1, ferritin, CRP) with the development of severe/moderate dengue (S/MD).

    Methods:

    We performed a nested case-control study from a multi-country study. A total of 281 S/MD and 556 uncomplicated dengue cases were included.

    Results:

    On days 1–3 from symptom onset, higher levels of any biomarker increased the risk of developing S/MD. When assessing together, SDC-1 and IL-1RA were stable, while IP-10 changed the association from positive to negative; others showed weaker associations. The best combinations associated with S/MD comprised IL-1RA, Ang-2, IL-8, ferritin, IP-10, and SDC-1 for children, and SDC-1, IL-8, ferritin, sTREM-1, IL-1RA, IP-10, and sCD163 for adults.

    Conclusions:

    Our findings assist the development of biomarker panels for clinical use and could improve triage and risk prediction in dengue patients.

    Funding:

    This study was supported by the EU's Seventh Framework Programme (FP7-281803 IDAMS), the WHO, and the Bill and Melinda Gates Foundation.

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