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Crystal structure of the yeast TFIIA/TBP/DNA complex
1Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06510, USA.
Science (New York, N.Y.)
|May 10, 1996
Summary
The crystal structure of yeast Transcription Factor II A (TFIIA) bound to TATA-binding protein (TBP) and DNA was determined. This reveals how TFIIA interacts with the TBP/TATA complex, facilitating transcription initiation.
Area of Science:
- Molecular Biology
- Structural Biology
- Biochemistry
Background:
- Transcription initiation in eukaryotes is a complex process involving numerous protein factors.
- Yeast Transcription Factor II A (TFIIA) plays a crucial role in stabilizing the pre-initiation complex.
- Understanding the structural basis of TFIIA-TBP-DNA interactions is key to deciphering transcription regulation.
Purpose of the Study:
- To elucidate the three-dimensional structure of the yeast TFIIA/TBP/TATA promoter complex.
- To define the molecular interactions between TFIIA, TBP, and the TATA DNA sequence.
- To provide insights into the mechanism of transcription pre-initiation complex assembly.
Main Methods:
- X-ray crystallography was employed to determine the structure.
- Double-edge multiple wavelength anomalous diffraction (MAD) was utilized.
- Two different anomalous scattering elements were incorporated within the same crystal for data collection.
Main Results:
- The crystal structure of the yeast TFIIA/TBP/TATA complex was resolved to 3 angstrom resolution.
- TFIIA associates as a heterodimer, forming a two-domain structure.
- TFIIA binds to the TBP/TATA complex on the opposite side of TFIIB, without disrupting TBP-DNA binding.
- Specific interactions were identified between TFIIA's beta-sandwich domain and TBP/TATA DNA, and its four-helix-bundle domain presents a surface for further interactions.
Conclusions:
- The determined structure reveals the precise binding mode of TFIIA within the transcription initiation complex.
- TFIIA's interaction mechanism stabilizes TBP binding to the TATA box.
- The structure highlights TFIIA's role in facilitating subsequent protein-protein interactions for transcription activation.
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