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Composite active site of an ABC ATPase: MutS uses ATP to verify mismatch recognition and authorize DNA repair

M S Junop1, G Obmolova, K Rausch

  • 1Laboratory of Molecular Biology, National Institute of Diabetes and Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.

Molecular Cell
|February 15, 2001
PubMed

Insights

The MutS protein initiates DNA mismatch repair by binding DNA and ATP. This binding is crucial for activating repair proteins, suggesting MutS acts as a proofreader in DNA repair.

Area of Science:

  • Molecular Biology
  • Biochemistry
  • Genetics

Background:

  • MutS protein initiates DNA mismatch repair (MMR).
  • MutS family proteins have conserved ATPase activity within the ATP binding cassette (ABC) superfamily.
  • MMR corrects errors in DNA replication.

Purpose of the Study:

  • To elucidate the structural and functional mechanism of MutS in DNA mismatch repair.
  • To investigate the role of MutS ATPase activity in MMR initiation.
  • To understand the interplay between DNA binding and ATP hydrolysis in MutS function.

Main Methods:

  • Determined the crystal structure of a ternary complex of MutS-DNA-ADP.
  • Performed biochemical assays to study the initiation of mismatch repair.
  • Utilized mutagenesis to perturb the ATPase active site of MutS.

Main Results:

  • The crystal structure reveals the ternary complex of MutS bound to DNA and ADP.
  • MutS requires simultaneous binding of both ATP and mismatch DNA to activate downstream repair proteins.
  • Perturbation of the ATPase active site affects MutS function in mismatch recognition and repair initiation.

Conclusions:

  • MutS functions as a crucial sensor and activator in the DNA mismatch repair pathway.
  • The ATPase activity of MutS is integral to its proofreading function, verifying mismatch recognition and authorizing repair.
  • Simultaneous binding of DNA and ATP by MutS is a key regulatory step for initiating MMR.

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