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Sequence-dependent contribution of distal binding domains to CAP protein-DNA binding affinity
D D Dalma-Weiszhausz1, M R Gartenberg, D M Crothers
1Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511.
Nucleic Acids Research
|February 11, 1991
Summary
Researchers measured how CAP protein binds to mutated DNA sequences. They found that dinucleotides, pairs of DNA bases, are key units influencing both CAP-DNA binding affinity and DNA bending. This helps understand protein-DNA interactions.
Area of Science:
- Molecular Biology
- Biophysics
- Genetics
Background:
- Understanding protein-DNA interactions is crucial for gene regulation.
- The CAP protein is a key transcription factor involved in bacterial gene expression.
- DNA sequence and structure influence protein binding and function.
Purpose of the Study:
- To investigate the relationship between DNA sequence, CAP protein binding affinity, and CAP-induced DNA bending.
- To identify the smallest DNA units responsible for quantitative interpretation of CAP-DNA interactions.
- To explore how sequence variations affect the energetics of protein-DNA complex formation.
Main Methods:
- Systematic mutagenesis of DNA sequences flanking the CAP consensus binding site.
- Measurement of relative binding affinities of CAP protein to mutated DNA sequences.
- Quantification of CAP-induced DNA bending using biophysical techniques.
Main Results:
- A moderate correlation was observed between binding free energy and the extent of DNA bending.
- Changes in binding affinity (up to 50-fold) were explained by additive dinucleotide contributions.
- The relative contributions of dinucleotides to binding and bending were generally similar.
- Dinucleotides were identified as the minimal units for quantitative analysis of distal CAP-DNA interactions.
Conclusions:
- Dinucleotides are fundamental units for understanding CAP-DNA binding and bending in regions outside the core binding site.
- Sequence-dependent DNA deformation energy and direct protein-DNA interaction energy both contribute to binding affinity.
- The study provides quantitative insights into the sequence determinants of CAP protein function.
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