Mediator Head module structure and functional interactions

Gang Cai, Tsuyoshi Imasaki, Kentaro Yamada, Francesco Cardelli, Yuichiro Takagi, Francisco J. Asturias

Research output: Contribution to journalArticle

67 Scopus citations


We used single-particle electron microscopy to characterize the structure and subunit organization of the Mediator Head module that controls Mediator-RNA polymerase II (RNAPII) and Mediator-promoter interactions. The Head module adopts several conformations differing in the position of a movable jaw formed by the Med18-Med20 subcomplex. We also characterized, by structural, biochemical and genetic means, the interactions of the Head module with TATA-binding protein (TBP) and RNAPII subunits Rpb4 and Rpb7. TBP binds near the Med18-Med20 attachment point and stabilizes an open conformation of the Head module. Rpb4 and Rpb7 bind between the Head jaws, establishing contacts essential for yeast-cell viability. These results, and consideration of the structure of the Mediator-RNAPII holoenzyme, shed light on the stabilization of the pre-initiation complex by Mediator and suggest how Mediator might influence initiation by modulating polymerase conformation and interaction with promoter DNA.

Original languageEnglish (US)
Pages (from-to)273-279
Number of pages7
JournalNature Structural and Molecular Biology
Issue number3
StatePublished - Mar 1 2010

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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