{
  "id": 9487122,
  "title": "A phiKMV ligase-dependent DNA repair mechanism that mitigates DNA-targeting nucleases",
  "url": "https://urgent.news/2026/09/23/a-phikmv-ligase-dependent-dna-repair-mechanism-that-mitigates-dna",
  "topic": "science",
  "section": "Science",
  "published": "2026-09-23T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.09.21.753257v1?rss=1"
  },
  "original_language": "en",
  "account": "Bacteria possess a variety of DNA-targeting mechanisms, such as restriction-modification and CRISPR-Cas, to defend against invading phage genomes. In response to these threats, phages develop countermeasures to either block or alleviate DNA damage. Researchers screened a collection of Pseudomonas aeruginosa phages against native and foreign DNA-targeting systems, discovering that the Phikmvvirus phage genus displayed broad resistance to multiple CRISPR-Cas and restriction-modification systems. After exposure to CRISPR-Cas12a, the majority of protospacer sequences maintained their genetic integrity. However, at an intergenic region adjacent to the CRISPR-Cas12a cleavage site, mutations emerged at a higher frequency than within the PAM or seed sequences, akin to repair-associated indels observed following genome editing in eukaryotic cells. Genetic screening efforts aimed at isolating Cas12a- and EcoRI-sensitive phage mutants uncovered disruptions in the phage DNA ligase. A phage strain resistant to Cas12a was restored by introducing DNA ligase from a different genetic source, and this rescue effect also reversed CRISPR targeting in a non-related phage. The findings suggest a mechanism whereby phiKMV-like phages manage to withstand specific nucleases through ligase-mediated repair of double-stranded breaks induced by nucleases.",
  "summary": "Bacteria employ diverse DNA-targeting systems, including restriction-modification (R-M) and CRISPR-Cas, to cleave invading bacteriophage genomes. In response, phages encode counter-defense strategies that block or mitigate DNA damage. Here, we screened a panel of Pseudomonas aeruginosa phages against native and heterologous DNA-targeting systems and identified the Phikmvvirus phage genus as…",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 2,
    "also_reported_by": [
      {
        "outlet": "bioRxiv",
        "title": "Interplay between flap endonuclease 1 and DNA polymerase β in long patch base excision repair: new facets in mechanism",
        "url": "https://urgent.news/2026/09/23/interplay-between-flap-endonuclease-1-and-dna-polymerase-in-long",
        "published": "2026-09-23T00:00:00.000Z"
      }
    ]
  },
  "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."
}