Mediator structural conservation and implications for the regulation mechanism.
Gang Cai1, Tsuyoshi Imasaki, Yuichiro Takagi
1Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
Structure (London, England : 1993)
|April 17, 2009
Summary
The yeast Mediator complex, crucial for transcription, exhibits inherent flexibility. This allows it to reorganize and interact with RNA polymerase II, revealing conserved regulatory mechanisms across eukaryotes.
Area of Science:
- Molecular Biology
- Structural Biology
- Biochemistry
Background:
- The Mediator complex is essential for regulating transcription initiation in eukaryotes.
- Understanding Mediator's structure and dynamics is key to deciphering gene expression control.
Purpose of the Study:
- To structurally characterize the yeast Mediator complex and its interaction with RNA polymerase II (RNAPII).
- To compare the structures of yeast and human Mediator complexes and their interaction dynamics.
Main Methods:
- Affinity purification was used to isolate pure yeast Mediator complex.
- Single-particle cryo-electron microscopy (cryo-EM) and conformational sorting were employed for structural analysis.
- Reconstructions of free and RNAPII-associated Mediator were compared.
Main Results:
- A high-resolution cryo-EM reconstruction of the yeast Mediator complex was obtained, revealing its inherent flexibility.
- Comparison of free and RNAPII-bound Mediator showed structural rearrangements enabling complex interactions.
- Yeast and human Mediator structures are highly conserved despite low sequence homology.
- Mediator's structural dynamics during RNAPII and nuclear receptor interactions show parallels.
Conclusions:
- Mediator's intrinsic flexibility is crucial for its interaction with RNAPII and transcriptional regulation.
- The conserved structure and dynamics of Mediator suggest a fundamental role in eukaryotic gene regulation.
- Mediator's structural adaptability is a key feature of conserved regulatory mechanisms.
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