Gene mutation assay using a MutS protein-modified electrode.

A novel electrochemical biosensor for gene mutation detection was developed using a DNA mismatch recognizing protein MutS from E. coli. The MutS protein was immobilized onto an Au electrode by coordination of His-tag at its C-terminus to vacant sites of Ni(II)-nitrilotriacetato complex attached to the surface of electrode. When a target DNA duplex having a mismatch site was captured by the MutS protein on the electrode, the electrostatic repulsion arose between polyanionic DNA duplexes and negatively-charged ferrocyanide/ferricyanide redox couple ions. Consequently, their redox peak currents on a cyclic voltammogram with the Au electrode drastically decreased depending on the concentration of the target DNA according to the redox couple-mediated artificial ion-channel principle. Using this assay, we could detect GT mismatch and deletion mutation in the double-stranded DNA.