Biosensors and methods to determine the activity of any and all nucleic acid binding factors, proteins, cellular events, nucleic acid binding protein coregulators, or fragments thereof, based upon the stabilization of the interaction of two nucleic acid components, which together comprise a complete nucleic acid binding element, by the binding of a nucleic acid binding factor are provided. Preferably, a fluorescence donor is attached to a nucleic acid comprising one portion or component of a complete nucleic acid binding element and a fluorescence acceptor is attached to a nucleic acid comprising the other portion or component of the same complete binding element. Alternatively, a solid substrate is attached to a nucleic acid comprising one portion of a binding element and a detectable label is attached to a nucleic acid comprising the other portion of the same binding element. Binding of a nucleic acid binding factor to the nucleic acid components affects a change in luminescence or the association of the detectable label with the solid substrate. These biosensors and methods may also be used to detect mediating nucleic acid binding factor coregulators, post-translational modifications and cellular events, to diagnose diseases and/or screen for drugs or other ligands that mediate the activity of nucleic acid binding factors.