Uncoupling Promoter Opening from Start-Site Scanning

Mol Cell. 2015 Jul 2;59(1):133-8. doi: 10.1016/j.molcel.2015.05.021. Epub 2015 Jun 11.

Abstract

Whereas RNA polymerase II (Pol II) transcription start sites (TSSs) occur about 30-35 bp downstream of the TATA box in metazoans, TSSs are located 40-120 bp downstream in S. cerevisiae. Promoter melting begins about 12 bp downstream in all eukaryotes, so Pol II is presumed to "scan" further downstream before starting transcription in yeast. Here we report that removal of the kinase complex TFIIK from TFIIH shifts the TSS in a yeast system upstream to the location observed in metazoans. Conversely, moving the normal TSS to an upstream location enables a high level of TFIIK-independent transcription in the yeast system. We distinguish two stages of the transcription initiation process: bubble formation by TFIIH, which fills the Pol II active center with single-stranded DNA, and subsequent scanning downstream, also driven by TFIIH, which requires displacement of the initial bubble. Omission of TFIIK uncouples the two stages of the process.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Nucleic Acid Conformation
  • Promoter Regions, Genetic
  • RNA Polymerase II / genetics*
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae Proteins / genetics*
  • Saccharomyces cerevisiae Proteins / metabolism
  • Transcription Factor TFIIH / genetics*
  • Transcription Factor TFIIH / metabolism
  • Transcription Initiation Site / physiology*
  • Transcription, Genetic / genetics

Substances

  • Saccharomyces cerevisiae Proteins
  • Transcription Factor TFIIH
  • RNA Polymerase II