Modeling the Abrupt Buckling Transition in dsDNA During Supercoiling

Abstract

When deoxyribonucleic (DNA), held at a fixed tension, is subjected to torsional deformations, it responds by forming plectonemic supercoils accompanied by a reduction in its endtoend extension. This transition from the extended state to the supercoiled state is marked by an abrupt buckling of the DNA accompanied by a rapid “hoppingâ€‌ of the DNA between the extended and supercoiled states. This transition is studied by means of Brownian dynamics simulations using a discrete wormlikechain (dWLC) model of DNA. The simulations reveal, among other things, the distinct regimes that occur during DNA supercoiling and the probabilities of states within the buckling transition regime.