Structure of a Complete Mediator-RNA Polymerase II Pre-Initiation Complex

Cell. 2016 Sep 8;166(6):1411-1422.e16. doi: 10.1016/j.cell.2016.08.050.


A complete, 52-protein, 2.5 million dalton, Mediator-RNA polymerase II pre-initiation complex (Med-PIC) was assembled and analyzed by cryo-electron microscopy and by chemical cross-linking and mass spectrometry. The resulting complete Med-PIC structure reveals two components of functional significance, absent from previous structures, a protein kinase complex and the Mediator-activator interaction region. It thereby shows how the kinase and its target, the C-terminal domain of the polymerase, control Med-PIC interaction and transcription.

Keywords: Mediator complex; Pre-initiation complex; RNA polymerase II carboxy-terminal domain; TFIIH; TFIIK; Transcription; cross-linking; cryo-EM; mass spectrometry.

Publication types

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

MeSH terms

  • Cryoelectron Microscopy
  • Gene Expression Regulation
  • Mass Spectrometry
  • Mediator Complex / chemistry*
  • Mediator Complex / metabolism*
  • Models, Molecular*
  • Phosphorylation
  • Protein Structure, Tertiary
  • Protein Subunits / chemistry
  • Protein Subunits / metabolism
  • RNA Polymerase II / chemistry*
  • RNA Polymerase II / metabolism*
  • Saccharomyces cerevisiae / enzymology*
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae Proteins / chemistry*
  • Saccharomyces cerevisiae Proteins / metabolism


  • Mediator Complex
  • Protein Subunits
  • Saccharomyces cerevisiae Proteins
  • RNA Polymerase II