Influence of supercoiling on the disruption of dsDNA

TL;DR

This paper presents a model showing that supercoiling energizes dsDNA, promoting localized unzipping by increasing thermal fluctuations, and draws an analogy to a second order phase transition with potential new critical exponents.

Contribution

It introduces a coupled elastic rod model demonstrating how supercoiling induces localized energy states that facilitate DNA unzipping, offering a new theoretical perspective.

Findings

Supercoiling creates localized high-energy regions in dsDNA.

Enhanced thermal fluctuations increase the probability of base pair disruption.

The unzipping transition is analogous to a second order phase transition with potential new critical exponents.

Abstract

We propose that supercoiling energizes double-stranded DNA (dsDNA) so as to facilitate thermal fluctuations to an unzipped state. We support this with a model of two elastic rods coupled via forces that represent base pair interactions. Supercoiling is shown to lead to a spatially localized higher energy state in a small region of dsDNA consisting of a few base pairs. This causes the distance between specific base pairs to be extended, enhancing the thermal probability for their disruption. Our theory permits the development of an analogy between this unzipping transition and a second order phase transition, for which the possibility of a new set of critical exponents is identified.