Uncoupling Promoter Opening from Start-Site Scanning

作者：Murakami Kenji; Mattei Pierre Jean; Davis Ralph E; Jin Huiyan; Kaplan Craig D; Kornberg Roger D^*

来源：Molecular Cell, 2015, 59(1): 133-138.

DOI：10.1016/j.molcel.2015.05.021

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 eu-karyotes, 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.

• 出版日期2015-7-2