Retron Eco2 breaks tRNAs for antiphage defense

Retron Eco2 breaks tRNAs for antiphage defense | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Biological Sciences - Article Retron Eco2 breaks tRNAs for antiphage defense Patrick Pausch, Monika Jasnauskaitė, Jonas Juozapaitis, Toma Liegutė, and 12 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7196019/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 18 Feb, 2026 Read the published version in Nature Structural & Molecular Biology → Version 1 posted You are reading this latest preprint version Abstract Retrons are prokaryotic reverse transcriptase systems that produce multicopy single-stranded DNA (msDNA), yet the principles by which they mediate antiviral defense remain largely unresolved. Here, we dissect the mechanism of Eco2, a minimal retron composed of a single reverse transcriptase–nuclease fusion protein. Cryogenic electron microscopy and hydrogen-deuterium exchange mass spectrometry reveal the structures and dynamics of a trimeric nucleoprotein complex assembled within a branched msDNA scaffold, which cages the TOPRIM nuclease. We show that the phage-encoded endonuclease DenB initiates msDNA degradation, thereby unblocking the nuclease active site. Activated Eco2 cuts tRNAs, resulting in translational shutdown for antiphage defense. We further identify ribosomal protein S1 as a putative RNA chaperone that associates with the msDNA precursor. These findings provide insights into the molecular mechanisms of minimal retrons and establish a structural basis for the engineering of Eco2. Biological sciences/Microbiology/Bacteriophages Biological sciences/Biochemistry/Structural biology/Electron microscopy/Cryoelectron microscopy Biological sciences/Biochemistry/Enzyme mechanisms Biological sciences/Molecular biology/Translation/tRNAs Full Text Additional Declarations There is NO Competing Interest. Supplementary Files JasnauskaiteetalSupplementary.pdf Supplementary Information Cite Share Download PDF Status: Published Journal Publication published 18 Feb, 2026 Read the published version in Nature Structural & Molecular Biology → Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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