Endonuclease that is involved in the suppression of homologous recombination and may therefore have a key role in the control of bacterial genetic diversity (Probable). Also involved in repairing oxidative DNA damage. Has ATPase activity. Binds DNA. ATPase activity is stimulated by DNA. Homodimer. Contains an N-terminal DNA-binding domain, followed by a dimerization domain and a C-terminal domain, called the small MutS-related (Smr) domain, which is absent from MutS and contains the endonuclease activity. Mutants have a significantly increased frequency of intergenomic recombination. They are more sensitive than wild-type cells to oxidative stress induced by agents such as H(2)O(2), paraquat or oxygen. They also have a reduced colonization capacity in a mouse model of infection. Belongs to the DNA mismatch repair MutS family. MutS2 subfamily.