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11:01
Application of Stopped-flow Kinetics Methods to Investigate the Mechanism of Action of a DNA Repair Protein
Published on: April 1, 2010
Distinct MutS DNA-binding modes that are differentially modulated by ATP binding and hydrolysis
L J Blackwell1, K P Bjornson, D J Allen
1Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA.
The Journal of Biological Chemistry
|July 17, 2001
Summary
Adenine nucleotides influence Escherichia coli MutS interactions with DNA. ATP stabilizes MutS complexes on heteroduplex DNA, but reduces mismatch specificity, while ADP enhances specificity.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- The precise role of MutS ATPase activity in DNA mismatch repair remains debated.
- Understanding MutS interactions with DNA is crucial for elucidating repair mechanisms.
Purpose of the Study:
- To investigate the impact of adenine nucleotides on Escherichia coli MutS binding to homoduplex and heteroduplex DNA.
- To clarify the function of MutS ATPase activity in DNA binding and mismatch recognition.
Main Methods:
- Surface plasmon resonance (SPR) was employed to analyze MutS-DNA interactions.
- Experiments were conducted under varying nucleotide conditions (ATP, ADP, AMPPNP) and ionic strengths.
Main Results:
- A physical block on linear heteroduplex DNA is sufficient for stable MutS complex formation with ATP.Mg(2+).
- The nucleotide present during initial binding affects the stability of MutS-DNA complexes.
- ATP and AMPPNP stabilize MutS on heteroduplex DNA but abolish mismatch specificity at physiological salt concentrations.
- Absence of nucleotide or presence of ADP maximizes mismatch specificity by reducing MutS affinity for homoduplex DNA.
Conclusions:
- MutS ATPase activity is critical for stable complex formation but can reduce DNA mismatch recognition specificity.
- ADP binding enhances MutS specificity for mismatched DNA, suggesting a regulatory role in mismatch repair.
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