Entropic Elasticity, Cooperative Extensibility and Supercoiling Property of DNA: A Unified Viewpoint

TL;DR

This paper presents a unified model of DNA elasticity, extensibility, and supercoiling, highlighting the dominant role of short-range basestacking interactions in DNA's mechanical behavior.

Contribution

The authors introduce a new structural parameter and develop a comprehensive model that aligns well with experimental data, emphasizing the importance of basestacking interactions.

Findings

The model accurately predicts DNA behavior under various torsional conditions.

Basestacking interactions are identified as the primary factor in DNA elasticity.

Theoretical results agree with experimental observations on supercoiled DNA.

Abstract

A unified model is constructed to study the recently observed DNA entropic elasticity, cooperative extensibility, and supercoiling property. With the introduction of a new structural parameter (the folding angle $\phi$), bending deformations of sugar-phosphate backbones, steric effects of nucleotide basepairs, and short-range basestacking interactions are considered. The comprehensive agreement of theoretical results with experimental observations on both torsionally relaxed and negatively supercoiled DNAs strongly indicates that, basestacking interactions, although short-ranged in nature, dominate the elasticity of DNA and hence are of vital biological significance.