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Published on: August 26, 2012
Mediator head subcomplex Med11/22 contains a common helix bundle building block with a specific function in
Martin Seizl1, Laurent Larivière, Toni Pfaffeneder
1Gene Center and Department of Biochemistry, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany.
Nucleic Acids Research
|April 19, 2011
Summary
The essential Med11/22 protein complex in RNA polymerase II transcription is structurally analyzed. A conserved surface patch on this complex is crucial for forming transcription pre-initiation complexes and may recruit TFIIH.
Area of Science:
- Molecular Biology
- Structural Biology
- Biochemistry
Background:
- The Mediator complex is a crucial co-activator for RNA polymerase II transcription.
- It comprises a conserved core with distinct 'head' and 'middle' modules.
Purpose of the Study:
- To perform a structure-function analysis of the Med11/22 heterodimer, a key component of the Mediator head module.
- To investigate the role of the Med11/22 structure in transcription pre-initiation complex formation and general transcription factor recruitment.
Main Methods:
- Structural analysis of the Med11/22 heterodimer.
- Biochemical assays to assess transcription pre-initiation complex formation in vitro.
- In vivo studies to evaluate the complex's function in transcription.
Main Results:
- Med11/22 forms a conserved four-helix bundle domain with C-terminal extensions that bind Med17.
- A conserved surface patch on the bundle domain is essential for stable transcription pre-initiation complex formation.
- This patch may mediate the recruitment of the general transcription factor TFIIH.
Conclusions:
- The four-helix bundle domain is a common structural motif in Mediator subunits, including the middle module and other heterodimers.
- This motif has been evolutionarily expanded and functionally diversified within the Mediator complex.
- The Med11/22 structure and its conserved surface patch play a critical role in regulating transcription initiation.
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