Cryo-em reveals new species-specific proteins and symmetry elements in the legionella pneumophila dot/icm t4ss

Michael J. Sheedlo, Clarissa L. Durie, Jeong Min Chung, Louise Chang, Jacquelyn Roberts, Michele Swanson, Dana Borden Lacy, Melanie D. Ohi

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

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.

Original languageEnglish (US)
Article numbere70427
JournaleLife
Volume10
DOIs
StatePublished - Sep 2021

Bibliographical note

Publisher Copyright:
‍© Sheedlo et al.

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