{
  "id": 18056513,
  "title": "Helicase family proteins promote antiviral ADP-ribosylation of DNA purines",
  "url": "https://urgent.news/2026/11/03/helicase-family-proteins-promote-antiviral-adp-ribosylation-of-dna",
  "topic": "science",
  "section": "Science",
  "published": "2026-11-03T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.11.02.763693v1?rss=1"
  },
  "original_language": "en",
  "account": "Researchers have discovered a new subfamily of DarTG defense systems that utilize helicase family proteins to promote antiviral ADP-ribosylation of DNA purines. These systems contain a DarT3 toxin, an ADP-ribosylhydrolase (ARH)-domain antitoxin, and a helicase family protein. The Escherichia coli DarHTG3 system is one such example, which requires DarH and modifies adenine in a way that is distinct from previously identified DarTG systems. By characterizing additional DarH-containing DarTG systems, researchers have found that some of these systems target both adenine and guanine. The data suggest that ADP-bound DarH functions as a processivity factor, recruiting DarT to the single-stranded DNA substrate and enabling ADP-ribosylation of multiple target sites. This new understanding of how helicase family proteins regulate antiviral effector mechanisms expands the functional repertoire of these proteins in bacterial immunity.",
  "summary": "DarTG defense systems studied to date contain a DarT1 or DarT2 toxin that blocks phage replication by ADP-ribosylating DNA and a NADAR or macrodomain antitoxin, DarG, that reverses this modification at homeostasis. Here, we identify additional DarTG subfamilies, one of which comprises a DarT3 toxin, an ADP-ribosylhydrolase (ARH)-domain antitoxin, and a helicase family protein, DarH. The…",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}