DNA metastability and biological regulation: conformational dynamics of metastable omega-DNA bulge loops.

Dynamic interchange between DNA conformations, including metastable states, can be of importance to biological function. In this study, we use a combination of spectroscopic and calorimetric techniques to detect and characterize kinetically trapped, metastable states in strand exchange and strand displacement reactions for bulge loop DNA conformations, here referred to as Omega-DNAs. We show that such metastable, Omega-DNA bulge loop states can stably coexist below 50 degrees C, while rearranging irreversibly at elevated temperatures to thermodynamically more stable states. Such dynamic interchange between metastable and globally stable DNA conformational states can be of importance in biological regulatory mechanisms.