Yeast Mediator facilitates transcription initiation at most promoters via a Tail-independent mechanism

Mol Cell. 2022 Nov 3;82(21):4033-4048.e7. doi: 10.1016/j.molcel.2022.09.016. Epub 2022 Oct 7.

Abstract

Mediator (MED) is a conserved factor with important roles in basal and activated transcription. Here, we investigate the genome-wide roles of yeast MED by rapid depletion of its activator-binding domain (Tail) and monitoring changes in nascent transcription. Rapid Tail depletion surprisingly reduces transcription from only a small subset of genes. At most of these Tail-dependent genes, in unperturbed conditions, MED is detected at both the UASs and promoters. In contrast, at most Tail-independent genes, we find MED primarily at promoters but not at the UASs. These results suggest that MED Tail and activator-mediated MED recruitment regulates only a small subset of genes. Furthermore, we define three classes of genes that differ in PIC assembly pathways and the requirements for MED Tail, SAGA, TFIID, and BET factors Bdf1/2. Our combined results have broad implications for the roles of MED, other coactivators, and mechanisms of transcriptional regulation at different gene classes.

Keywords: BET factors; Mediator; SAGA; TFIID; coactivator; stress response; transcription; transcription activation; transcription factor; transcription initiation.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Promoter Regions, Genetic
  • Saccharomyces cerevisiae Proteins* / metabolism
  • Saccharomyces cerevisiae* / genetics
  • Saccharomyces cerevisiae* / metabolism
  • Transcription Factor TFIID / genetics
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • Transcription, Genetic

Substances

  • Saccharomyces cerevisiae Proteins
  • Transcription Factor TFIID
  • BDF1 protein, S cerevisiae
  • Transcription Factors