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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.
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http://dx.doi.org/10.1016/j.cell.2016.08.050 | DOI Listing |
Proc Natl Acad Sci U S A
April 2023
Department of Molecular Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen 37077, Germany.
For transcription initiation, RNA polymerase II (Pol II) forms a preinitiation complex (PIC) that associates with the general coactivator Mediator. Whereas atomic models of the human PIC-Mediator structure have been reported, structures for its yeast counterpart remain incomplete. Here, we present an atomic model for the yeast PIC with core Mediator, including the Mediator middle module that was previously poorly resolved and including subunit Med1 that was previously lacking.
View Article and Find Full Text PDFNature
June 2021
Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
Mediator is a conserved coactivator complex that enables the regulated initiation of transcription at eukaryotic genes. Mediator is recruited by transcriptional activators and binds the pre-initiation complex (PIC) to stimulate the phosphorylation of RNA polymerase II (Pol II) and promoter escape. Here we prepare a recombinant version of human Mediator, reconstitute a 50-subunit Mediator-PIC complex and determine the structure of the complex by cryo-electron microscopy.
View Article and Find Full Text PDFInt J Dev Biol
February 2022
Laboratorio Nacional de Genómica para la Biodiversidad (Langebio), Unidad de Genómica Avanzada, Centro de Investigaciones y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), Irapuato, Guanajuato, Mexico.
Mediator is a conserved transcriptional co-activator that links transcription factors bound at enhancer elements to RNA Polymerase II. Mediator-RNA Polymerase II interactions can be sterically hindered by the Cyclin Dependent Kinase 8 (CDK8) module, a submodule of Mediator that acts to repress transcription in response to discrete cellular and environmental cues. The CDK8 module is conserved in all eukaryotes and consists of 4 proteins: CDK8, CYCLIN C (CYCC), MED12, and MED13.
View Article and Find Full Text PDFNature
April 2017
Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla California, USA.
The conserved Mediator co-activator complex has an essential role in the regulation of RNA polymerase II transcription in all eukaryotes. Understanding the structure and interactions of Mediator is crucial for determining how the complex influences transcription initiation and conveys regulatory information to the basal transcription machinery. Here we present a 4.
View Article and Find Full Text PDFJ Biol Chem
December 2016
From the Stowers Institute for Medical Research, Kansas City, Missouri 64110,
Mediator plays an integral role in activation of RNA polymerase II (Pol II) transcription. A key step in activation is binding of Mediator to Pol II to form the Mediator-Pol II holoenzyme. Here, we exploit a combination of biochemistry and macromolecular EM to investigate holoenzyme assembly.
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