Stretching, Twisting and Supercoiling in Short, Single DNA Molecules

TL;DR

This paper extends a DNA supercoiling model to short DNA molecules, revealing significant differences in torque and supercoiling behavior compared to long DNA, highlighting increased flexibility in short DNA.

Contribution

It combines existing models to accurately describe the mechanics of short, twisted DNA, providing new insights into its flexibility and supercoiling properties.

Findings

Short DNA exhibits significantly different torque and supercoiling behavior.

The free energy of short DNA is markedly different from that of infinite-length DNA.

Short DNA is more flexible than previously assumed.

Abstract

We had combined the Neukirch-Marko model that describes the extension, torque and supercoiling in single, stretched and twisted DNA of infinite contour length, with a form of the free energy suggested by Sinha and Samuels to describe short DNA, with contour length only a few times the persistence length. We find that the free energy of the stretched but untwisted DNA, is significantly modified from its infinitely length value and this in turn modifies significantly the torque and supercoiling. We show that this is consistent with short DNA being more flexible than infinitely long DNA. We hope our results will stimulate experimental investigation of torque and supercoiling in short DNA.