Cryo-EM reveals new species-specific proteins and symmetry elements in the Legionella pneumophila Dot/Icm T4SS
- Vanderbilt University Medical Center, United States
- University Of Michigan, United States
- University of Michigan, United States
- Vanderbilt University School of Medicine, United States
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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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.
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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Cryo-EM reveals new species-specific proteins and symmetry elements in the Legionella pneumophila Dot/Icm T4SS
eLife 10:e70427.
https://doi.org/10.7554/eLife.70427
