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Yeast TATA-binding protein TFIID binds to TATA elements with both consensus and nonconsensus DNA sequences
S Hahn1, S Buratowski, P A Sharp
1Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
Summary
Yeast TFIID binds TATA elements with high affinity and specificity. It recognizes both consensus and non-consensus TATA sequences, suggesting a single TATA-binding factor is sufficient for transcription initiation.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- The TATA element is a crucial promoter sequence in eukaryotes, recognized by the TATA-binding protein (TBP), a subunit of transcription factor IID (TFIID).
- Understanding the precise DNA binding properties of TFIID is essential for elucidating the mechanisms of transcription initiation.
- Previous studies suggested the existence of multiple TATA-binding factors due to the diversity of TATA-like sequences found in various promoters.
Purpose of the Study:
- To investigate the DNA binding characteristics of the yeast TATA element-binding protein TFIID.
- To determine the affinity and specificity of TFIID for both consensus and non-consensus TATA sequences.
- To assess the functional relevance of TFIID binding to non-consensus TATA elements in transcription.
Main Methods:
- The study employed DNA binding assays to measure the affinity of TFIID for various TATA elements.
- In vitro transcription assays were performed to evaluate the functional activity of TFIID with different TATA sequences.
- Comparative analysis of binding affinities for consensus versus non-consensus TATA sequences was conducted.
Main Results:
- Yeast TFIID exhibits high affinity (2 x 10(-9) M) for the consensus adenovirus major late promoter TATA element.
- TFIID demonstrates remarkable specificity, binding non-specific sites with approximately 10(5)-fold lower affinity.
- Crucially, TFIID binds with high affinity to several non-consensus TATA elements, including those from yeast LEU2, simian virus 40, and yeast CYC1 promoters.
- TFIID actively promoted in vitro transcription from these non-consensus TATA elements.
Conclusions:
- The findings indicate that a single TATA-binding factor, TFIID, can recognize a range of TATA sequences, including non-consensus variants.
- The ability of TFIID to bind and activate transcription from diverse TATA elements challenges the notion that multiple TATA-binding factors are necessary.
- This study provides strong evidence supporting the role of a single, versatile TFIID in initiating transcription from promoters with varying TATA element sequences.