Architecture and mechanism of a dual-enzyme retron system in prokaryotic immunity.

ABSTRACT: Retrons are bacterial genetic retroelements encoding a reverse transcriptase (RT) and a non-coding RNA (ncRNA)-multi-copy single-stranded DNA (msDNA) hybrid. Diverse effector proteins or domains are found to associate with retrons, typically forming tripartite toxin-antitoxin systems involved in anti-phage defense. Although retrons have attracted growing interest in genome editing technologies, the mechanisms underlying most retron-mediated immune systems remain poorly understood. Here, we characterize a distinct quaternary retron system, Ec78, harboring a dual-component effector complex in which the PtuA ATPase and PtuB nuclease act in concert to mediate phage clearance. The cryo-EM structure of the Ec78 complex adopts a flower-basket-like architecture, with two Ec78 retrons engaging the

SUBMITTER: Li X 

PROVIDER: S-EPMC12804668 | biostudies-literature | 2025 Dec

REPOSITORIES: biostudies-literature