The effect of DNA conformation changes on the coupling of the macromolecule deformation components

TL;DR

This paper models DNA deformation considering both external bending, twisting, stretching, and internal conformational mobility, revealing how their coupling explains experimental twist-stretch behaviors under force.

Contribution

It introduces a coupled deformation model of DNA that accounts for internal conformational changes, explaining complex mechanical responses observed experimentally.

Findings

Coupling between internal and external deformation components affects DNA's mechanical response.

The model explains the transition from compression to tension at critical forces.

Results align with experimental observations of DNA behavior under force.

Abstract

The model of the deformation of DNA macromolecule is developed with the accounting of two types of components of deformation: external and internal. External components describe the bend, twist and stretch of the double helix. The internal component - the conformational mobility inside of the double helix. In the work the deformation of DNA macromolecule is considered taking into account the coupling of the external component (of deformation) with the internal component (of conformational change). Under the task consideration the macromolecule twist-stretch coupling and coupling between twist and internal component are taken into account. The solution obtained in these conditions for the deformation components allows changing the character of respond in stretch component on unwind (overwind) in dependence on the applied force to twist component. The changing of the character of deformation from compression to tension achieving of critical untwisting force (and vise versa the changing of the character of deformation from overwind to unwind at critical tension force)is known from the single molecular experiments. The nature of such unexpected behavior of double helix have clarified in the present work by including in consideration the internal component. The obtained solutions and their conformity to experimental results show the essential role of coupling between internal and external components in the double helix conformational mechanics under action force in pN range.