Kinetics of Proximity-Induced Intramolecular DNA Strand Displacement

Proximity-induced intramolecular DNA strand displacement (PiDSD) is one of the key mechanisms involved in many DNA-mediated proximity assays and protein-responsive DNA devices. However, the kinetic profile of PiDSD has never been systematically examined before. Herein, we report a systematic study to explore the kinetics of PiDSD by combining the uses of three DNA strand displacement techniques, including a binding-induced DNA strand displacement to generate PiDSD, an intermolecular DNA strand-exchange strategy to measure a set of key kinetic parameters for PiDSD, and a toehold-mediated DNA strand displacement to generate fluorescence signals for the real-time monitoring of PiDSD. By using this approach, we have successfully revealed the kinetic profiles of PiDSD, determined the enhanced local effective concentrations of DNA probes that are involved in PiDSD, and identified a number of key factors that influence the kinetics of PiDSD. Our study on PiDSD establishes knowledge and strategies that can be used to guide the design and operation of various DNA-mediated proximity assays and protein-triggered DNA devices.