{
  "abstract": "Antiviral defence systems frequently utilise cyclic nucleotide second messengers. A prominent example is the type III CRISPR-Cas system, which generates cyclic oligoadenylates (cOA) on detecting viral RNA. cOA molecules can bind and activate a wide range of effectors to provide antiviral defence. In both prokaryotes and higher plants, activation of a catalytic Toll/Interleukin Receptor (TIR) domain by multimerization results in degradation of NAD+, limiting cell metabolism and thus viral replication. Here, we describe a CRISPR-associated TIR-containing effector that includes a SAVED (SMODS-associated and fused to various effector domains) domain for nucleotide sensing and a cOA-degrading ring nuclease Crn4 domain. We demonstrate that the TIR-SAVED-Ring nuclease (TSR1) effector binds cA3, resulting in activation of the TIR NADase activity. The Crn4 domain, which imposes an unusual dimeric quaternary structure on the effector, degrades cA3, providing a mechanism to auto-deactivate the effector. TSR1 is thus a highly unusual example of a dimeric and self-limiting TIR effector in antiviral immunity.",
  "abstract_shown": true,
  "affiliations": [
    "University of St Andrews"
  ],
  "article_type": "New results",
  "arxiv": null,
  "author_total": 4,
  "authors": [
    {
      "name": "Y. Sun"
    },
    {
      "name": "S. McMahon"
    },
    {
      "name": "S. Snyowsky"
    },
    {
      "affs": [
        0
      ],
      "name": "M. F. White"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/73nev4bkepwyd.bib",
  "cited_by": 0,
  "doi": "10.64898/2026.09.16.751991",
  "fulltext_url": "https://www.biorxiv.org/content/10.64898/2026.09.16.751991v1.full",
  "id": "73nev4bkepwyd",
  "issns": [],
  "landing_url": "https://www.biorxiv.org/content/10.64898/2026.09.16.751991v1",
  "language": null,
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "biorxiv",
      "microbiology"
    ],
    [
      "openalex",
      "1312|CRISPR and Genetic Engineering"
    ]
  ],
  "openalex": "W7213558824",
  "pdf_url": "https://www.biorxiv.org/content/10.64898/2026.09.16.751991v1.full.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-16",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/73nev4bkepwyd.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:23:05Z",
      "native_id": "10.64898/2026.09.16.751991",
      "source": "biorxiv",
      "url": "https://www.biorxiv.org/content/10.64898/2026.09.16.751991v1"
    }
  ],
  "subjects": [
    {
      "field": "biology",
      "origin": "biorxiv:microbiology",
      "subfield": "microbiology"
    }
  ],
  "title": "A self-limiting dimeric TIR effector specialised for type III CRISPR-mediated immunity",
  "title_text": "A self-limiting dimeric TIR effector specialised for type III CRISPR-mediated immunity",
  "type": "preprint",
  "updated_at": "2026-10-30T12:23:05Z",
  "url": "https://research.draconitic.com/paper/73nev4bkepwyd",
  "venue": "bioRxiv",
  "versions": []
}