Molecular architecture of the yeast Mediator complex
Philip J Robinson,
Michael J Trnka,
Riccardo Pellarin,
Charles H Greenberg,
David A Bushnell,
Ralph Davis,
Alma L Burlingame,
Andrej Sali,
Roger D Kornberg
Affiliations
Philip J Robinson
Department of Structural Biology, Stanford University School of Medicine, Stanford, United States
Michael J Trnka
Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, United States
Riccardo Pellarin
Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Chemistry, California Institute for Quantitative Biosciences, University of California, San Francisco, San Francisco, United States; Structural Bioinformatics Unit, Paris, France
Charles H Greenberg
Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Chemistry, California Institute for Quantitative Biosciences, University of California, San Francisco, San Francisco, United States
David A Bushnell
Department of Structural Biology, Stanford University School of Medicine, Stanford, United States
Ralph Davis
Department of Structural Biology, Stanford University School of Medicine, Stanford, United States
Alma L Burlingame
Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, United States
Andrej Sali
Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Chemistry, California Institute for Quantitative Biosciences, University of California, San Francisco, San Francisco, United States
Roger D Kornberg
Department of Structural Biology, Stanford University School of Medicine, Stanford, United States
The 21-subunit Mediator complex transduces regulatory information from enhancers to promoters, and performs an essential role in the initiation of transcription in all eukaryotes. Structural information on two-thirds of the complex has been limited to coarse subunit mapping onto 2-D images from electron micrographs. We have performed chemical cross-linking and mass spectrometry, and combined the results with information from X-ray crystallography, homology modeling, and cryo-electron microscopy by an integrative modeling approach to determine a 3-D model of the entire Mediator complex. The approach is validated by the use of X-ray crystal structures as internal controls and by consistency with previous results from electron microscopy and yeast two-hybrid screens. The model shows the locations and orientations of all Mediator subunits, as well as subunit interfaces and some secondary structural elements. Segments of 20–40 amino acid residues are placed with an average precision of 20 Å. The model reveals roles of individual subunits in the organization of the complex.
