Abstract
The TATA-binding protein (TBP) initiates assembly of transcription preinitiation complexes on eukaryotic class II promoters, binding to and restructuring consensus and variant "TATA box" sequences. The sequence dependence of the DNA structure in TBP-TATA complexes has been investigated in solution using fluorescence resonance energy transfer. The mean 5'dye-3'dye distance varies significantly among oligomers bearing the adenovirus major late promoter sequence (AdMLP) and five single-site variants bound to Saccharomyces cerevisiae TBP, consistent with solution bend angles for AdMLP of 76 degrees and for the variants ranging from 30 degrees to 62 degrees. These solution bends contrast sharply with the corresponding co-crystal structures, which show approximately 80 degrees bends for all sequences. Transcription activities for these TATA sequences are strongly correlated with the solution bend angles but not with TBP-DNA binding affinities. Our results support a model in which transcription efficiency derives primarily from the sequence-dependent structure of the TBP-TATA binary complex. Specifically, the distance distribution for the average solution structure of the TBP-TATA complex may reflect the sequence-dependent probability for the complex to assume a conformation in which the TATA box DNA is severely bent. Upon assumption of this geometry, the binary complex becomes a target for binding and correctly orienting the other components of the preinitiation complex.
Highlights
The TATA-binding protein (TBP)1 binds to eukaryotic class II promoters at specific sequences of DNA of the consensus sequence TATA(a/t)A(a/t)N, nucleating assembly of the pro
The mean 5dye-3dye distance varies significantly among oligomers bearing the adenovirus major late promoter sequence (AdMLP) and five single-site variants bound to Saccharomyces cerevisiae TBP, consistent with solution bend angles for AdMLP of 76° and for the variants ranging from 30° to 62°
Our results support a model in which transcription efficiency derives primarily from the sequence-dependent structure of the TBP1⁄7TATA binary complex
Summary
The TATA-binding protein (TBP) binds to eukaryotic class II promoters at specific sequences of DNA of the consensus sequence TATA(a/t)A(a/t)N, nucleating assembly of the pro-. The reference AdMLP and five variant TATA sequences bound to TBP have significantly different mean end-to-end distances in solution. These distances are consistent with DNA bend angles ranging from 29.9° to 61.8° for the variant sequences and 76.2° for the native AdMLP. A strong correlation is observed between the solution bend angles and the transcription activities [6] These findings are consistent with the structure of TBP1⁄7TATA complexes being a principal determinant of TATA-box-dependent transcription activity. A model is proposed that reconciles the sequence dependence of bend angles and transcription activities measured in solution with the DNA structures observed in the co-crystals
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