A fluorescent reporter on electrostatic DNA-ligand interactions.

Among the various types of interactions between biomolecules, electrostatic interactions dominate as these are long-range interactions and are often a generic first step in the recruitment of specific ligands. DNA, being a highly charged molecule, attracts a plethora of molecules. Interactions between DNA and proteins or small molecules shape the overall function of the cell. Various processes such as DNA replication, DNA repair, synthesis of mRNA, and packaging of DNA are mediated by interactions between protein molecules and DNA that are predominantly electrostatic. Here, we present a fluorescence resonance energy transfer (FRET)-based probe which can report on the electrostatic interactions between the negatively-charged DNA and positively-charged metal ions, oligopeptides, as well as DNA groove-binding drug molecules. The simplicity, sensitivity, and versatility of the DNA-based probe makes it suited for applications where specific protein-DNA interactions can be probed, and DNA-binding drugs can be discovered in high-throughput screens of compound libraries. This is particularly relevant given that some of the most potent antitumor and antimicrobial drugs associate with DNA electrostatically.