DNA bends in TATA-binding protein-TATA complexes in solution are DNA sequence-dependent.

Area of Science:

• Molecular Biology
• Biochemistry
• Genetics

Background:

• TATA-binding protein (TBP) is crucial for initiating transcription at eukaryotic class II promoters.
• TBP binds to and restructures TATA box DNA sequences, influencing gene expression.
• Understanding the structural dynamics of TBP-TATA complexes is key to deciphering transcription regulation.

Purpose of the Study:

• To investigate the sequence-dependent structural changes in TBP-TATA complexes in solution.
• To correlate DNA bending angles with transcription activity and TBP-DNA binding affinities.
• To elucidate the role of DNA structure in the TBP-TATA binary complex for preinitiation complex assembly.

Main Methods:

• Utilized fluorescence resonance energy transfer (FRET) to measure distances in TBP-TATA complexes in solution.
• Synthesized oligomers with the adenovirus major late promoter (AdMLP) sequence and single-site variants.
• Compared solution structures with existing X-ray crystallography data.

Main Results:

• Solution bend angles for TBP-AdMLP complexes varied significantly (30-76 degrees), contrasting with crystal structures (approx. 80 degrees).
• Transcription activities strongly correlated with solution bend angles, but not TBP-DNA binding affinities.
• Sequence-specific DNA bending in the TBP-TATA complex influences transcription efficiency.

Conclusions:

• Transcription efficiency is primarily determined by the sequence-dependent structure of the TBP-TATA binary complex.
• The probability of adopting a severely bent DNA conformation dictates the formation of a functional preinitiation complex.
• This structural flexibility allows for precise orientation of other transcription factors, regulating gene expression.