Torque spectroscopy of DNA: Basepair stability, boundary effects, backbending, and breathing dynamics
Florian C. Oberstrass, Louis E. Fernandes, Paul Lebel, and Zev Bryant
Accepted
Changes in global DNA linking number can be accommodated by localized changes in helical structure. We have used single-molecule torque measurements to investigate sequence-specific strand separation and Z-DNA formation. By controlling the boundary conditions at the edges of sequences of interest, we have confirmed theoretical predictions of distinctive boundary-dependent backbending patterns in torque-twist relationships. Abrupt torque jumps are associated with the formation and collapse of DNA bubbles, permitting direct observations of DNA breathing dynamics.