MutS binds G-T mismatches and G4 DNA. (A) Mobility shift assays demonstrating that wild-type MutS binds G-T mismatches. Lanes contain increasing concentrations of MutS from 4.7 to 300 nM generated by a 1:1 serial dilution. Each lane contains 20 fmols radiolabeled G-T mismatch substrate. B, oligonucleotide bound by MutS; U, unbound. (B) As in A except 10 fmols of radiolabeled TP-G4 were utilized as the substrate per reaction with 1.2-150 nM MutS (C) MutS binds to G4 DNA with high affinity. Graph depicting the percent of G-T mismatch (white) bound by MutS and percent G4 (grey) bound by MutS. Data (Additional file 2) represent the mean of three independent experiments with standard error.