MutS stimulates the endonuclease activity of MutL in an ATP-hydrolysis-dependent manner

FEBS J. 2013 Jul;280(14):3467-79. doi: 10.1111/febs.12344. Epub 2013 Jun 18.

Abstract

In the initial steps of DNA mismatch repair, MutS recognizes a mismatched base and recruits the latent endonuclease MutL onto the mismatch-containing DNA in concert with other proteins. MutL then cleaves the error-containing strand to introduce an entry point for the downstream excision reaction. Because MutL has no intrinsic ability to recognize a mismatch and discriminate between newly synthesized and template strands, the endonuclease activity of MutL is strictly regulated by ATP-binding in order to avoid nonspecific degradation of the genomic DNA. However, the activation mechanism for its endonuclease activity remains unclear. In this study, we found that the coexistence of a mismatch, ATP and MutS unlocks the ATP-binding-dependent suppression of MutL endonuclease activity. Interestingly, ATPase-deficient mutants of MutS were unable to activate MutL. Furthermore, wild-type MutS activated ATPase-deficient mutants of MutL less efficiently than wild-type MutL. We concluded that ATP hydrolysis by MutS and MutL is involved in the mismatch-dependent activation of MutL endonuclease activity.

Keywords: ATP hydrolysis; DNA mismatch repair; MutL; MutS; endonuclease activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases / antagonists & inhibitors
  • Adenosine Triphosphatases / chemistry
  • Adenosine Triphosphatases / metabolism*
  • Adenosine Triphosphate / chemistry*
  • DNA Mismatch Repair
  • Enzyme Activation
  • Hydrolysis
  • Kinetics
  • MutS DNA Mismatch-Binding Protein / chemistry
  • MutS DNA Mismatch-Binding Protein / metabolism*
  • Plasmids / genetics
  • Protein Structure, Tertiary
  • Thermus thermophilus / enzymology*

Substances

  • Adenosine Triphosphate
  • Adenosine Triphosphatases
  • MutS DNA Mismatch-Binding Protein