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Elife. 2015 Sep 24;4. pii: e08719. doi: 10.7554/eLife.08719.

Molecular architecture of the yeast Mediator complex.

Author information

1
Department of Structural Biology, Stanford University School of Medicine, Stanford, United States.
2
Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, United States.
3
Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Chemistry, California Institute for Quantitative Biosciences, University of California, San Francisco, San Francisco, United States.
4
Structural Bioinformatics Unit, Paris, France.

Abstract

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.

KEYWORDS:

RNA polymerase II; S. cerevisiae; biophysics; cross-linking; mass spectrometry; modeling; structural biology; transcriptional regulation

PMID:
26402457
PMCID:
PMC4631838
DOI:
10.7554/eLife.08719
[Indexed for MEDLINE]
Free PMC Article

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