{
  "id": 8155719,
  "title": "A superfamily 1 helicase translocates on double-stranded DNA",
  "url": "https://urgent.news/2026/09/17/a-superfamily-1-helicase-translocates-on-double-stranded-dna",
  "topic": "science",
  "section": "Science",
  "published": "2026-09-17T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.09.16.752024v1?rss=1"
  },
  "original_language": "en",
  "account": "Replicative and accessory helicases are crucial for preserving genome integrity during DNA replication and repair processes. The Rep helicase, belonging to the superfamily 1 (SF1), represents the first helicase family to be solved at atomic resolution, serving as a model for how helicases couple ATP hydrolysis to movement on DNA. Researchers have employed optical tweezers in conjunction with fluorescence imaging to examine how Rep translocates and navigates through various nucleic acid and protein impediments. Direct observation reveals highly processive translocation on single-stranded DNA, occurring at a rate of approximately 300 nucleotides per second over a stretch of 13,000 nucleotides. The movement of Rep is shown to drive single-stranded DNA-binding proteins, including bacterial SSB, archaeal SSB, and eukaryotic RPA, along single-stranded DNA without a decrease in speed. Upon encountering a short duplex barrier of 60 base pairs or less, which can be either a DNA duplex or an RNA/DNA hybrid, Rep frequently bypasses it. Termination and unwinding are also noted during this process. Interestingly, an unexpected mode is identified where Rep transitions from ssDNA onto dsDNA and translocates directionally along the duplex with high processivity, covering a distance of 12,000 base pairs at a significantly faster rate (~1100 base pairs per second) compared to its speed on single-stranded DNA. AlphaFold3 modeling supports the hypothesis that Rep tracks a single strand while maintaining the duplex intact. This marks the first demonstration of processive dsDNA translocation by an SF1 helicase, expanding current models of how translocases operate on DNA during replication and repair processes.",
  "summary": "Replicative and accessory helicases are essential for maintaining genome integrity during DNA replication and repair. Rep helicase belongs to superfamily 1 (SF1), the first helicase family solved at atomic resolution and a longstanding model for how helicases couple ATP hydrolysis to movement on DNA. Using optical tweezers combined with fluorescence imaging, we characterize how Rep translocates…",
  "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."
}