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A downstream initiation element required for efficient TATA box binding and in vitro function of TFIID.
Y Nakatani1, M Horikoshi, M Brenner
1Laboratory of Molecular Biology, NINDS, National Institutes of Health, Bethesda, Maryland 20892.
Nature
|November 1, 1990
Summary
The glial fibrillary acidic protein (gfa) gene promoter requires both a TATA box and a downstream initiator element for efficient transcription. Natural human TFIID binds both elements, unlike cloned versions, suggesting additional factors enhance transcription initiation.
Area of Science:
- Molecular Biology
- Gene Regulation
- Neuroscience
Background:
- The glial fibrillary acidic protein (gfa) gene encodes a key intermediate filament protein in glial cells.
- Promoter analysis revealed two distinct initiation elements in the human gfa gene: a TATA box and a downstream initiator element.
Purpose of the Study:
- To investigate the functional roles of the gfa promoter's TATA box and downstream initiator element in transcription.
- To characterize the binding properties of natural human TFIID and cloned TFIIDs to these promoter elements.
Main Methods:
- Transfection assays were used to assess the requirement of promoter elements for transcription in cultured cells.
- In vitro transcription assays and DNase footprinting were performed with partially purified natural human TFIID and bacterially expressed cloned TFIIDs.
- Deletion analysis of the gfa promoter was conducted.
Main Results:
- Both the TATA box and the downstream initiator element are essential for efficient gfa gene transcription.
- Natural human TFIID binds to both the TATA box and the downstream initiator, while cloned human and yeast TFIIDs primarily bind the TATA box.
- Deletion of the downstream initiator impaired TFIID binding to the TATA box and reduced transcription.
- Cloned TFIIDs showed less dependence on the downstream initiator for TATA box binding and transcription.
Conclusions:
- Efficient transcription of the gfa gene requires the cooperative action of the TATA box and the downstream initiator.
- Natural human TFIID likely possesses an additional component that interacts with the downstream initiator, stabilizing TFIID binding and promoting transcription.