{
  "id": 10428568,
  "title": "Reconstitution of +1 nucleosome transcription reveals coordinated functions of SAGA, Mediator, and TFIIH",
  "url": "https://urgent.news/2026/09/28/reconstitution-of-1-nucleosome-transcription-reveals-coordinated",
  "topic": "science",
  "section": "Science",
  "published": "2026-09-28T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.09.24.754195v1?rss=1"
  },
  "original_language": "en",
  "account": "A recent study has unveiled the intricate coordination between the +1 nucleosome and three key transcription factors - SAGA, Mediator, and TFIIH - in eukaryotic transcription. The researchers constructed a system utilizing eleven purified yeast factors, including RNA polymerase II, six general transcription factors, TFIIS, the activator Pho4, and the SAGA and Mediator complexes. This system accurately reflects the regulation observed in living organisms. The SAGA complex, in collaboration with Pho4, orchestrates the precise positioning of the pre-initiation complex (PIC) by facilitating TBP loading onto the +1 nucleosome. On the other hand, Mediator enhances transcription when the +1 nucleosome obstructs PIC formation, presumably by stabilizing the productive TFIIH-DNA interaction. Interestingly, unlike the widely accepted model, SAGA remains attached to the PIC after TBP loading and acetylates the +1 nucleosome within the assembled complex. Even more intriguingly, the isolated PIC-Mediator-SAGA-nucleosome complex exhibits transcriptional activity on its own. The repressive effects of the nucleosome on transcription are alleviated through the DNA translocase activity of Ssl2, the TFIIH subunit responsible for unwinding the promoter DNA. Ultimately, TFIIH synergistically melts the promoter DNA while simultaneously remodeling the +1 nucleosome, thus facilitating transcription initiation.",
  "summary": "The +1 nucleosome has emerged as a key regulator of eukaryotic transcription, but how it controls transcription initiation remains poorly understood. Here we reconstitute transcription through the +1 nucleosome using eleven purified yeast factors: RNA polymerase II (Pol II), the six general transcription factors (GTFs), TFIIS, the activator Pho4, and the SAGA and Mediator complexes. The system…",
  "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."
}