8V45

CryoEM structure of AriA-Ocr complex

8V45 の概要

• エントリーDOI: 10.2210/pdb8v45/pdb
• EMDBエントリー: 42965
• 分子名称: AriA antitoxin, Protein Ocr, ADENOSINE-5'-TRIPHOSPHATE (3 entities in total)
• 機能のキーワード: bacterial defense system, toxin-antitoxin system, ariab, paris, immune system
• 由来する生物種: Escherichia coli B185; 詳細
• タンパク質・核酸の鎖数: 8
• 化学式量合計: 349395.34

構造登録者

Deep, A.,Corbett, K.D. (登録日: 2023-11-28, 公開日: 2024-06-26, 最終更新日: 2024-10-16)

主引用文献

Deep, A.,Liang, Q.,Enustun, E.,Pogliano, J.,Corbett, K.D.
Architecture and activation mechanism of the bacterial PARIS defence system.
Nature, 634:432-439, 2024

PubMed Abstract: Bacteria and their viruses (bacteriophages or phages) are engaged in an intense evolutionary arms race. While the mechanisms of many bacterial antiphage defence systems are known, how these systems avoid toxicity outside infection yet activate quickly after infection is less well understood. Here we show that the bacterial phage anti-restriction-induced system (PARIS) operates as a toxin-antitoxin system, in which the antitoxin AriA sequesters and inactivates the toxin AriB until triggered by the T7 phage counterdefence protein Ocr. Using cryo-electron microscopy, we show that AriA is related to SMC-family ATPases but assembles into a distinctive homohexameric complex through two oligomerization interfaces. In uninfected cells, the AriA hexamer binds to up to three monomers of AriB, maintaining them in an inactive state. After Ocr binding, the AriA hexamer undergoes a structural rearrangement, releasing AriB and allowing it to dimerize and activate. AriB is a toprim/OLD-family nuclease, the activation of which arrests cell growth and inhibits phage propagation by globally inhibiting protein translation through specific cleavage of a lysine tRNA. Collectively, our findings reveal the intricate molecular mechanisms of a bacterial defence system triggered by a phage counterdefence protein, and highlight how an SMC-family ATPase has been adapted as a bacterial infection sensor.

PubMed: 39112702
DOI: 10.1038/s41586-024-07772-8

実験手法

ELECTRON MICROSCOPY (3.63 Å)