Nonlinear Mechanical Response of DNA due to Anisotropic Bending Elasticity

TL;DR

This paper investigates how anisotropic bending rigidity in DNA leads to nonlinear responses, including kink formation and curvature modulations, influenced by the DNA's helical structure and elastic properties.

Contribution

It introduces a model accounting for anisotropic bending in DNA, revealing nonlinear twist-bend coupling effects not previously characterized.

Findings

Anisotropy causes nonlinear twist-bend coupling in DNA.

Kinks and modulations form depending on elastic constants.

Modulation wavelength is approximately half the DNA pitch.

Abstract

The response of a short DNA segment to bending is studied, taking into account the anisotropy in the bending rigidities caused by the double-helical structure. It is shown that the anisotropy introduces an effective nonlinear twist-bend coupling that can lead to the formation of kinks and modulations in the curvature and/or in the twist, depending on the values of the elastic constants and the imposed deflection angle. The typical wavelength for the modulations, or the distance between the neighboring kinks is found to be set by half of the DNA pitch.