ATP-hydrolysis-dependent conformational switch modulates the stability of MutS-mismatch complexes

Area of Science:

• Molecular biology
• Biochemistry
• Genetics

Background:

• The mismatch repair (MMR) pathway corrects errors during DNA replication.
• The role of nucleotide cofactors in regulating MMR, particularly MutS protein function, is debated.
• Understanding MutS conformational changes is key to elucidating MMR mechanisms.

Purpose of the Study:

• To investigate the effect of nucleotide binding (ADP and ATP) on MutS protein conformation.
• To determine how DNA binding influences the nucleotide-dependent conformational switch in MutS.
• To propose a model for MutS conformational states during mismatch recognition and repair.

Main Methods:

• In vitro studies of MutS protein interactions.
• Analysis of MutS conformation upon binding to DNA and nucleotides (ADP, ATP, ATPgammaS).
• Comparison of MutS behavior with homo- and heteroduplex DNA.

Main Results:

• Nucleotide binding to MutS induces a conformational switch.
• This switch occurs with ATP but not ADP when MutS is bound to DNA.
• The conformational change is similar for both homo- and heteroduplex DNA.
• A three-state model for MutS conformation is proposed: nucleotide-free, ATP hydrolysis-dependent, and ATP binding-dependent.

Conclusions:

• MutS conformational states are regulated by nucleotide binding and DNA interaction.
• ATP binding, rather than ADP, is critical for the conformational switch in DNA-bound MutS.
• These findings provide insights into the in vivo mechanisms of mismatch recognition and DNA repair site searching.