Using stable MutS dimers and tetramers to quantitatively analyze DNA mismatch recognition and sliding clamp formation.

ABSTRACT: The process of DNA mismatch repair is initiated when MutS recognizes mismatched DNA bases and starts the repair cascade. The Escherichia coli MutS protein exists in an equilibrium between dimers and tetramers, which has compromised biophysical analysis. To uncouple these states, we have generated stable dimers and tetramers, respectively. These proteins allowed kinetic analysis of DNA recognition and structural analysis of the full-length protein by X-ray crystallography and small angle X-ray scattering. Our structural data reveal that the tetramerization domains are flexible with respect to the body of the protein, resulting in mostly extended structures. Tetrameric MutS has a slow dissociation from DNA, which can be due to occasional bending over and binding DNA in its two binding sites.

SUBMITTER: Groothuizen FS 

PROVIDER: S-EPMC3783165 | biostudies-literature | 2013 Sep

REPOSITORIES: biostudies-literature