9NH2

In situ cryo-EM structure of porin III of the Legionella Dot/Icm T4SS machine

これはPDB形式変換不可エントリーです。

9NH2 の概要

• エントリーDOI: 10.2210/pdb9nh2/pdb
• EMDBエントリー: 49395
• 分子名称: Outer membrane protein beta-barrel domain-containing protein (1 entity in total)
• 機能のキーワード: type ivb dot/icm secretion machine, protein transport
• 由来する生物種: Legionella pneumophila subsp. pneumophila
• タンパク質・核酸の鎖数: 16
• 化学式量合計: 421832.59

構造登録者

Yue, J.,Liu, J. (登録日: 2025-02-23, 公開日: 2025-09-17, 最終更新日: 2025-11-12)

主引用文献

Yue, J.,Heydari, S.,Park, D.,Chetrit, D.,Tachiyama, S.,Guo, W.,Botting, J.M.,Wu, S.,Roy, C.R.,Liu, J.
In situ structures of the Legionella Dot/Icm T4SS identify the DotA-IcmX complex as the gatekeeper for effector translocation.
Proc.Natl.Acad.Sci.USA, 122:e2516300122-e2516300122, 2025

PubMed Abstract: The Dot/Icm machine of is among the most versatile type IV secretion systems (T4SSs), capable of translocating more than 330 distinct effector proteins across the bacterial envelope into host cells. Assembly and function of the system require at least 27 Dot and Icm proteins, yet its architecture and activation mechanism remain poorly understood at the molecular level. Here, we deploy in situ single-particle cryoelectron microscopy to determine near-atomic structures of the Dot/Icm machine and its intimate association with three distinct outer membrane porins in intact bacteria. Notably, two essential yet enigmatic components, DotA and IcmX, form a pentameric protochannel in an inactive state at the central axis of the Dot/Icm machine. Upon Dot/Icm activation with host lysate, this protochannel undergoes extensive rearrangements to generate an extended transenvelope conduit, as visualized by cryoelectron tomography (cryo-ET) and subtomogram averaging. Furthermore, a combination of cryo-ET and cryo-FIB milling of macrophages infected with reveals tethering of the Dot/Icm machine to the host membrane, suggesting direct translocation of effector proteins from the bacterial cytoplasm into the host. Together, our studies identify the DotA-IcmX complex as a gatekeeper for effector translocation and provide a molecular framework for understanding the assembly and activation of the elaborate Dot/Icm T4SS.

PubMed: 40986344
DOI: 10.1073/pnas.2516300122

実験手法

ELECTRON MICROSCOPY (4.05 Å)