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Interaction between the cyclic AMP receptor protein and DNA. Conformational studies
B Blazy1, F Culard, J C Maurizot
1Laboratoire de Biophysique Interactions Moleculaires, Universite Paul Sabatier, Toulouse, France.
Journal of Molecular Biology
|May 5, 1987
Summary
Circular dichroism spectroscopy reveals how cyclic adenosine 3
Area of Science:
- Molecular Biology
- Biophysics
Background:
- Escherichia coli cyclic adenosine 3',5' monophosphate receptor protein (CRP or CAP) regulates gene expression.
- CRP binding to DNA is crucial for transcription regulation, but its structural effects on DNA are complex.
Purpose of the Study:
- To investigate the conformational changes in DNA upon binding of CRP using circular dichroism (c.d.) spectroscopy.
- To examine the influence of cAMP and cGMP on CRP-DNA interactions and DNA conformation.
Main Methods:
- Circular dichroism (c.d.) spectroscopy was employed to study CRP binding to various DNA sequences.
- The effects of varying ionic strength and the presence of cAMP/cGMP were analyzed.
Main Results:
- CRP binding induces significant DNA conformational changes, independent of DNA sequence, potentially forming a solenoidal coil.
- The extent of DNA conformational change correlates with CRP saturation and is influenced by the presence of cAMP and cGMP.
- Specific lac operon binding results in distinct DNA conformational changes compared to non-specific binding.
Conclusions:
- CRP binding induces significant and variable DNA structural alterations.
- The conformational plasticity of DNA in response to CRP binding is a key feature of gene regulation.