In situ molecular organization and heterogeneity of the Legionella Dot/Icm T4SS

Authors

• Przemysław Dutka, Division of Biology and Biological Engineering
• Yuxi Liu, Division of Biology and Biological Engineering
• Stefano Maggi, Division of Biology and Biological Engineering
• Debnath Ghosal, Division of Biology and Biological Engineering
• Jue Wang, Division of Biology and Biological Engineering
• Prashant P. Damke, University of Kentucky
• Stephen D. Carter, Division of Biology and Biological Engineering
• Wei Zhao, Division of Biology and Biological Engineering
• Sukhithasri Vijayrajratnam, Washington University School of Medicine in St. Louis
• Joseph P. Vogel, Washington University School of Medicine in St. Louis
• Carrie L. Shaffer, University of KentuckyFollow
• Grant J. Jensen, Division of Biology and Biological EngineeringFollow

Abstract

The Dot/Icm type IV secretion system (T4SS) is essential for Legionella pneumophila infection, but its in situ architecture and mechanism remain incompletely understood. Using cryo-electron tomography, we performed subtomogram averaging and 3D classification to resolve structural heterogeneity within the complex. We identified multiple assembly states of the inner membrane complex, including a fully assembled form with a hexamer-of-dimers DotO ATPase and symmetry mismatches between subcomplexes. A composite in situ model revealed a central channel above the inner membrane, likely used for substrate secretion. Imaging of infected macrophages showed T4SSs tethered to host vacuoles and extracellular vesicle release, suggesting additional effector delivery routes. These findings provide insight into Dot/Icm T4SS structure and infection-related dynamics.

Document Type

Article

Publication Date

6-1-2026

Notes/Citation Information

Publisher Copyright: © 2026 The Author(s). FEBS Letters published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.

Digital Object Identifier (DOI)

10.1002/1873-3468.70270

Archival?

Archival

Repository Citation

Dutka, Przemysław; Liu, Yuxi; Maggi, Stefano; Ghosal, Debnath; Wang, Jue; Damke, Prashant P.; Carter, Stephen D.; Zhao, Wei; Vijayrajratnam, Sukhithasri; Vogel, Joseph P.; Shaffer, Carrie L.; and Jensen, Grant J., "In situ molecular organization and heterogeneity of the Legionella Dot/Icm T4SS" (2026). Markey Cancer Center Faculty Publications. 512.
https://uknowledge.uky.edu/markey_facpub/512