Can pulling cause right- to left-handed structural transitions in negatively supercoiled DNA double-helix?

TL;DR

This paper presents a theoretical study showing that pulling on negatively supercoiled DNA can induce a transition from right-handed B-form to a left-handed Z-like form, aligning with some experimental findings.

Contribution

It introduces a model predicting a structural transition in supercoiled DNA under tension, highlighting a possible right-to-left handed transition not previously characterized.

Findings

Pulling can induce a B-to-Z-like transition in negatively supercoiled DNA.

The transition energetics are calculated and qualitatively match experimental observations.

The model provides insights into DNA structural behavior under mechanical stress.

Abstract

The folding angle distribution of stretched and negatively supercoiled DNA double-helix is investigated based on a theoretical model we proposed earlier [H. Zhou et al., Phys. Rev. Lett. 82, 4560 (1999)]. It is shown that pulling can transit a negatively supercoiled DNA double-helix from the right-handed B-form to a left-handed configuration which resembles DNA Z-form in some important respects. The energetics of this possible transition is calculated and the comparison with recent experimental observations are qualitatively discussed.