DNA synthesis involved in DNA repair / double-strand break repair / endonuclease activity / defense response to virus / ATP hydrolysis activity / ATP binding 類似検索 - 分子機能
: / Retron Ec78 putative HNH endonuclease-like / AAA domain, group 15 / AAA ATPase domain / ATPases associated with a variety of cellular activities / AAA+ ATPase domain / P-loop containing nucleoside triphosphate hydrolase 類似検索 - ドメイン・相同性
ジャーナル: Science / 年: 2025 タイトル: Disassembly activates Retron-Septu for antiphage defense. 著者: Chen Wang / Anthony D Rish / Emily G Armbruster / Jiale Xie / Anna B Loveland / Zhangfei Shen / Bradley Gu / Andrei A Korostelev / Joe Pogliano / Tian-Min Fu / 要旨: Retrons are antiphage defense systems that produce multicopy single-stranded DNA (msDNA) and hold promises for genome engineering. However, the mechanisms of defense remain unclear. The Retron-Septu ...Retrons are antiphage defense systems that produce multicopy single-stranded DNA (msDNA) and hold promises for genome engineering. However, the mechanisms of defense remain unclear. The Retron-Septu system uniquely integrates retron and Septu antiphage defenses. Cryo-electron microscopy structures reveal asymmetric nucleoprotein complexes comprising a reverse transcriptase (RT), msDNA (a hybrid of msdDNA and msrRNA), and two PtuAB copies. msdDNA and msrRNA are essential for assembling this complex, with msrRNA adopting a conserved lariat-like structure that regulates reverse transcription. Notably, the assembled Retron-Septu complex is inactive, with msdDNA occupying the PtuA DNA-binding site. Activation occurs upon disassembly, releasing PtuAB, which degrades single-stranded DNA to restrict phage replication. This "arrest-and-release" mechanism underscores the dynamic regulatory roles of msDNA, advancing our understanding of antiphage defense strategies.