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Water release associated with specific binding of gal repressor
1Laboratory of Theoretical and Physical Biology, NICHD, National Institutes of Health, Bethesda, MD 20892, USA.
The EMBO Journal
|March 15, 1995
Summary
Gal repressor binding to DNA releases 130 water molecules, with specific binding releasing more water than non-specific interactions. This water release is crucial for understanding DNA-protein interactions and binding specificity.
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- Protein-DNA interactions are fundamental to cellular processes.
- Understanding the energetic contributions to DNA binding specificity is key.
- Gal repressor is a well-studied model system for DNA binding.
Purpose of the Study:
- To quantify water release during gal repressor-DNA association.
- To correlate water release with binding affinity and specificity.
- To investigate the role of hydration in DNA-protein recognition.
Main Methods:
- Measuring binding constants under varying osmotic pressures using neutral solutes.
- Utilizing sucrose to probe excluded volume effects and hydration changes.
- Comparing water release for specific and non-specific DNA sequences.
Main Results:
- Specific binding of gal repressor to operator DNA released approximately 130 water molecules.
- No significant water release was observed for non-specific binding to poly(dI-dC).(dI-dC).
- A difference of six water molecules was detected between closely related operator sequences with differing affinities.
Conclusions:
- Water release is a significant energetic component of specific gal repressor-DNA binding.
- Hydration dynamics play a critical role in determining DNA binding specificity.
- Osmotic pressure measurements provide a sensitive method to study hydration changes in molecular recognition.