Structural highlights
Function
[MED7_YEAST] Component of the Mediator complex, a coactivator involved in the regulated transcription of nearly all RNA polymerase II-dependent genes. Mediator functions as a bridge to convey information from gene-specific regulatory proteins to the basal RNA polymerase II transcription machinery. The Mediator complex, having a compact conformation in its free form, is recruited to promoters by direct interactions with regulatory proteins and serves for the assembly of a functional preinitiation complex with RNA polymerase II and the general transcription factors. The Mediator complex unfolds to an extended conformation and partially surrounds RNA polymerase II, specifically interacting with the unphosphorylated form of the C-terminal domain (CTD) of RNA polymerase II. The Mediator complex dissociates from the RNA polymerase II holoenzyme and stays at the promoter when transcriptional elongation begins.[1] [2] [3] [MED21_YEAST] Component of the Mediator complex, a coactivator involved in the regulated transcription of nearly all RNA polymerase II-dependent genes. Mediator functions as a bridge to convey information from gene-specific regulatory proteins to the basal RNA polymerase II transcription machinery. The Mediator complex, having a compact conformation in its free form, is recruited to promoters by direct interactions with regulatory proteins and serves for the assembly of a functional preinitiation complex with RNA polymerase II and the general transcription factors. The Mediator complex unfolds to an extended conformation and partially surrounds RNA polymerase II, specifically interacting with the unphosphorylated form of the C-terminal domain (CTD) of RNA polymerase II. The Mediator complex dissociates from the RNA polymerase II holoenzyme and stays at the promoter when transcriptional elongation begins.[4] [5] [6]
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
The Mediator of transcriptional regulation is the central coactivator that enables a response of RNA polymerase II (Pol II) to activators and repressors. We present the 3.0-A crystal structure of a highly conserved part of the Mediator, the MED7.MED21 (Med7.Srb7) heterodimer. The structure is very extended, spanning one-third of the Mediator length and almost the diameter of Pol II. It shows a four-helix bundle domain and a coiled-coil protrusion connected by a flexible hinge. Four putative protein binding sites on the surface allow for assembly of the Mediator middle module and for binding of the conserved subunit MED6, which is shown to bridge to the Mediator head module. A flexible MED6 bridge and the MED7.MED21 hinge could account for changes in overall Mediator structure upon binding to Pol II or activators. Our results support the idea that transcription regulation involves conformational changes within the general machinery.
A conserved mediator hinge revealed in the structure of the MED7.MED21 (Med7.Srb7) heterodimer.,Baumli S, Hoeppner S, Cramer P J Biol Chem. 2005 May 6;280(18):18171-8. Epub 2005 Feb 14. PMID:15710619[7]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Kang JS, Kim SH, Hwang MS, Han SJ, Lee YC, Kim YJ. The structural and functional organization of the yeast mediator complex. J Biol Chem. 2001 Nov 9;276(45):42003-10. Epub 2001 Sep 12. PMID:11555651 doi:http://dx.doi.org/10.1074/jbc.M105961200
- ↑ Nair D, Kim Y, Myers LC. Mediator and TFIIH govern carboxyl-terminal domain-dependent transcription in yeast extracts. J Biol Chem. 2005 Oct 7;280(40):33739-48. Epub 2005 Aug 2. PMID:16076843 doi:http://dx.doi.org/M506067200
- ↑ Takagi Y, Kornberg RD. Mediator as a general transcription factor. J Biol Chem. 2006 Jan 6;281(1):80-9. Epub 2005 Nov 1. PMID:16263706 doi:http://dx.doi.org/M508253200
- ↑ Kang JS, Kim SH, Hwang MS, Han SJ, Lee YC, Kim YJ. The structural and functional organization of the yeast mediator complex. J Biol Chem. 2001 Nov 9;276(45):42003-10. Epub 2001 Sep 12. PMID:11555651 doi:http://dx.doi.org/10.1074/jbc.M105961200
- ↑ Nair D, Kim Y, Myers LC. Mediator and TFIIH govern carboxyl-terminal domain-dependent transcription in yeast extracts. J Biol Chem. 2005 Oct 7;280(40):33739-48. Epub 2005 Aug 2. PMID:16076843 doi:http://dx.doi.org/M506067200
- ↑ Takagi Y, Kornberg RD. Mediator as a general transcription factor. J Biol Chem. 2006 Jan 6;281(1):80-9. Epub 2005 Nov 1. PMID:16263706 doi:http://dx.doi.org/M508253200
- ↑ Baumli S, Hoeppner S, Cramer P. A conserved mediator hinge revealed in the structure of the MED7.MED21 (Med7.Srb7) heterodimer. J Biol Chem. 2005 May 6;280(18):18171-8. Epub 2005 Feb 14. PMID:15710619 doi:10.1074/jbc.M413466200
