Dual redox labeling of DNA as a tool for electrochemical detection of p53 protein-DNA interactions.

We present a novel dual redox labeling approach enabling a facile relative evaluation of protein-DNA interactions based on immunoprecipitation at magnetic beads (MBIP) with subsequent electrochemical detection. DNA probes labeled with two different electroactive markers, benzofurazane and nitrobenzene, which yield reduction peaks at distinct potentials, were synthesized using primer extension (PEX) reaction. We show that using the labeled DNA probes, specific and non-specific binding of the p53 protein can be distinguished in a simple competition binding experiment, as a strong preference of the p53 protein was observed towards DNA probes bearing a specific p53 binding site (p53CON), which is in agreement with known binding properties of the p53 protein. The p53 binding to the individual DNA probes can be modulated by specific monoclonal antibodies used for the immunoprecipitation. This approach can potentially be applied, after selection of appropriate DNA probes and monoclonal antibodies, for investigations of DNA-binding properties of other proteins and thus represents a versatile tool for studies of any DNA-binding proteins.