Covalently trapping MutS on DNA to study DNA mismatch recognition and signalingElectronic supplementary information (ESI) available: SDS-PAGE analysis of MutS-DNA crosslinking specificity and kinetics; tables of plasmids, proteins, oligodeoxyribonucleotides and DNA duplexes, experimental details of trapping MutS on DNA and ternary complex formation with MutL. See DOI: 10.1039/c2mb25086a

The DNA repair protein MutS forms clamp-like structures on DNA that search for and recognize base mismatches leading to ATP-transformed signaling clamps. In this study, the mobile MutS clamps were trapped on DNA in a functional state using single-cysteine variants of MutS and thiol-modified homoduplex or heteroduplex DNA. This approach allows stabilization of various transient MutS-DNA complexes and will enable their structural and functional analysis. An efficient transient protein-DNA trapping approach based on 3′-disulfide DNA modification.