1. Microbiology and Infectious Disease
Download icon

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
Research Article
  • Cited 0
  • Views 338
  • Annotations
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)

Article and author information

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. Accepted: September 14, 2021
  3. Accepted Manuscript published: September 14, 2021 (version 1)

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.

Metrics

  • 338
    Page views
  • 96
    Downloads
  • 0
    Citations

Article citation count generated by polling the highest count across the following sources: Crossref, PubMed Central, Scopus.

Download links

A two-part list of links to download the article, or parts of the article, in various formats.

Downloads (link to download the article as PDF)

Download citations (links to download the citations from this article in formats compatible with various reference manager tools)

Open citations (links to open the citations from this article in various online reference manager services)

Further reading

    1. Medicine
    2. Microbiology and Infectious Disease
    Alexander O Pasternak et al.
    Research Article Updated

    Background:

    It remains unclear whether combination antiretroviral therapy (ART) regimens differ in their ability to fully suppress human immunodeficiency virus (HIV) replication. Here, we report the results of two cross-sectional studies that compared levels of cell-associated (CA) HIV markers between individuals receiving suppressive ART containing either a non-nucleoside reverse transcriptase inhibitor (NNRTI) or a protease inhibitor (PI).

    Methods:

    CA HIV unspliced RNA and total HIV DNA were quantified in two cohorts (n = 100, n = 124) of individuals treated with triple ART regimens consisting of two nucleoside reverse transcriptase inhibitors (NRTIs) plus either an NNRTI or a PI. To compare CA HIV RNA and DNA levels between the regimens, we built multivariable models adjusting for age, gender, current and nadir CD4+ count, plasma viral load zenith, duration of virological suppression, NRTI backbone composition, low-level plasma HIV RNA detectability, and electronically measured adherence to ART.

    Results:

    In both cohorts, levels of CA HIV RNA and DNA strongly correlated (rho = 0.70 and rho = 0.54) and both markers were lower in NNRTI-treated than in PI-treated individuals. In the multivariable analysis, CA RNA in both cohorts remained significantly reduced in NNRTI-treated individuals (padj = 0.02 in both cohorts), with a similar but weaker association between the ART regimen and total HIV DNA (padj = 0.048 and padj = 0.10). No differences in CA HIV RNA or DNA levels were observed between individual NNRTIs or individual PIs, but CA HIV RNA was lower in individuals treated with either nevirapine or efavirenz, compared to PI-treated individuals.

    Conclusions:

    All current classes of antiretroviral drugs only prevent infection of new cells but do not inhibit HIV RNA transcription in long-lived reservoir cells. Therefore, these differences in CA HIV RNA and DNA levels by treatment regimen suggest that NNRTIs are more potent in suppressing HIV residual replication than PIs, which may result in a smaller viral reservoir size.

    Funding:

    This work was supported by ZonMw (09120011910035) and FP7 Health (305522).

    1. Evolutionary Biology
    2. Microbiology and Infectious Disease
    Emily R Ebel et al.
    Research Article

    The replication of Plasmodium falciparum parasites within red blood cells (RBCs) causes severe disease in humans, especially in Africa. Deleterious alleles like hemoglobin S are well-known to confer strong resistance to malaria, but the effects of common RBC variation are largely undetermined. Here we collected fresh blood samples from 121 healthy donors, most with African ancestry, and performed exome sequencing, detailed RBC phenotyping, and parasite fitness assays. Over one third of healthy donors unknowingly carried alleles for G6PD deficiency or hemoglobinopathies, which were associated with characteristic RBC phenotypes. Among non-carriers alone, variation in RBC hydration, membrane deformability, and volume was strongly associated with P. falciparum growth rate. Common genetic variants in PIEZO1, SPTA1/SPTB, and several P. falciparum invasion receptors were also associated with parasite growth rate. Interestingly, we observed little or negative evidence for divergent selection on non-pathogenic RBC variation between Africans and Europeans. These findings suggest a model in which globally widespread variation in a moderate number of genes and phenotypes modulates P. falciparum fitness in RBCs.