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-Structure paper
| タイトル | Structural mechanism of the Retron-Eco7 anti-phage defense system. |
|---|---|
| ジャーナル・号・ページ | Nat Commun, Vol. 16, Issue 1, Page 10821, Year 2025 |
| 掲載日 | 2025年12月2日 |
著者 | Junichiro Ishikawa / Kanta Yoneyama / Aa Haeruman Azam / Asuteka Nagao / Yoshihisa Mitsuda / Ren Nakazaki / Kotaro Chihara / Masahiro Hiraizumi / Keitaro Yamashita / Tsutomu Suzuki / Kotaro Kiga / Hiroshi Nishimasu / ![]() |
| PubMed 要旨 | Retrons are prokaryotic genetic elements involved in anti-phage defense and consist of a non-coding RNA, a reverse transcriptase (RT), and various effector proteins. Retron-Eco7 (previously known as ...Retrons are prokaryotic genetic elements involved in anti-phage defense and consist of a non-coding RNA, a reverse transcriptase (RT), and various effector proteins. Retron-Eco7 (previously known as Retron-Ec78) from Escherichia coli encodes two effector proteins (the PtuA ATPase and the PtuB nuclease) and degrades the host tRNA upon phage infection, thereby protecting host cells against invading phages. However, its defense mechanism remains elusive. Here, we report the cryo-electron microscopy (cryo-EM) structures of the Retron-Eco7 complex, comprising the RT, multicopy single-stranded DNA (msDNA), PtuA, and PtuB. The Retron-Eco7 structures reveal that the RT-msDNA complex associates with two PtuA-PtuB complexes, potentially inhibiting their nuclease activity and suppressing bacterial growth arrest prior to phage infection. Furthermore, the phage-encoded D15 nuclease acts as a trigger for the Retron-Eco7 system and cleaves the msDNA bound to the complex, facilitating the dissociation of PtuA-PtuB from RT-msDNA. Our data indicate that msDNA cleavage by D15 is the initial step required for the specific cleavage of the host tRNA by the PtuA-PtuB nuclease, which leads to abortive infection. Overall, this study provides mechanistic insights into the Retron-Eco7 system and highlights the diversity of prokaryotic anti-phage defense mechanisms. |
リンク | Nat Commun / PubMed:41330933 / PubMed Central |
| 手法 | EM (単粒子) |
| 解像度 | 2.58 - 2.76 Å |
| 構造データ | EMDB-62378, PDB-9kjx: EMDB-62379, PDB-9kjy: EMDB-62380, PDB-9kjz: EMDB-62381, PDB-9kk1: EMDB-62382, PDB-9kk2: |
| 化合物 | ![]() ChemComp-ADP: ![]() ChemComp-ZN: ![]() ChemComp-MG: |
| 由来 |
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キーワード | RNA BINDING PROTEIN / Retron / Reverse transcriptase |
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