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-Structure paper
| タイトル | Phage nuclease-mediated defense activation of the bacterial Retron-Eco7 toxin-antitoxin system. |
|---|---|
| ジャーナル・号・ページ | Nucleic Acids Res, Vol. 53, Issue 21, Year 2025 |
| 掲載日 | 2025年11月13日 |
著者 | Zhikang Dai / Chang Liu / Yanjing Wang / Xueting Chen / Xiaofang Fu / Kaiyue Yang / Rui Zhu / Xianyue Jia / Yanke Chen / Pan Tao / Zeyuan Guan / Tingting Zou / ![]() |
| PubMed 要旨 | Retrons are bacterial antiphage defense systems comprising a reverse transcriptase (RT), a non-coding RNA (ncRNA), and cognate effector proteins. The RT synthesizes multicopy single-stranded DNA ...Retrons are bacterial antiphage defense systems comprising a reverse transcriptase (RT), a non-coding RNA (ncRNA), and cognate effector proteins. The RT synthesizes multicopy single-stranded DNA (msDNA) from the ncRNA template to detect phage invasion. This study focuses on Retron-Eco7, which integrates retron-based sensing with the effector module of Septu-a characterized antiphage system in which the PtuAB complex mediates nuclease-dependent defense. However, the activation mechanism of this hybrid system remains unclear. Here, we determined cryo-electron microscopy structures of the RT-msDNA-PtuAB quaternary complex and the PtuAB binary complex in Retron-Eco7. Structural analyses reveal that the DNA stem-loop of msDNA extensively interacts with PtuA subunits via electrostatic interactions. We establish Retron-Eco7 as a novel toxin-antitoxin system, in which RT-msDNA acts as the antitoxin, directly binding and neutralizing the PtuAB toxin. Furthermore, we identified a phage-encoded flap endonuclease as a trigger for Retron-Eco7 activation, which cleaves msDNA to release the PtuAB toxin. Our findings demonstrate the diversity in bacterial retron defense systems and uncover a novel activation mechanism of the Septu-derived retron toxin-antitoxin system. |
リンク | Nucleic Acids Res / PubMed:41277685 / PubMed Central |
| 手法 | EM (単粒子) |
| 解像度 | 2.5 - 3.4 Å |
| 構造データ | EMDB-65052, PDB-9vh1: EMDB-65064, PDB-9vhe: EMDB-65070, PDB-9vhl: |
| 化合物 | ![]() ChemComp-ZN: ![]() ChemComp-ATP: ![]() ChemComp-MG: |
| 由来 |
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キーワード | DNA BINDING PROTEIN / retron-Eco7 / toxin-antitoxin / DNA BINDING PROTEIN/RNA/DNA / DNA BINDING PROTEIN-RNA-DNA complex |
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