Download MendeleyDNA end sensing and cleavage by the Shedu anti-phage defense system.
Loeff, L., Walter, A., Rosalen, G.T., Jinek, M.(2025) Cell 188: 721
- PubMed: 39742808 Search on PubMed
- DOI: https://doi.org/10.1016/j.cell.2024.11.030
- Primary Citation Related Structures:
8PS4, 8PS5, 8PS6 - PubMed Abstract:
The detection of molecular patterns associated with invading pathogens is a hallmark of innate immune systems. Prokaryotes deploy sophisticated host defense mechanisms in innate anti-phage immunity. Shedu is a single-component defense system comprising a putative nuclease SduA. Here, we report cryoelectron microscopy (cryo-EM) structures of apo- and double-stranded DNA (dsDNA)-bound tetrameric SduA assemblies, revealing that the N-terminal domains of SduA form a clamp that recognizes free DNA ends. End binding positions the DNA over the PD-(D/E)XK nuclease domain, resulting in dsDNA nicking at a fixed distance from the 5' end. The end-directed DNA nicking activity of Shedu prevents propagation of linear DNA in vivo. Finally, we show that phages escape Shedu immunity by suppressing their recombination-dependent DNA replication pathway. Taken together, these results define the antiviral mechanism of Shedu systems, underlining the paradigm that recognition of pathogen-specific nucleic acid structures is a conserved feature of innate immunity across all domains of life.
- Department of Biochemistry, University of Zurich, Zurich, Switzerland. Electronic address: l.loeff@gmail.com.
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