Elucidation of Conformational Hysteresis on a Giant DNA

TL;DR

This study investigates the conformational hysteresis of giant DNA influenced by condensing agents, combining experimental observations with theoretical simulations to understand the folding-unfolding pathways and stability of different DNA conformations.

Contribution

It provides a combined experimental and Monte Carlo simulation analysis revealing how chain stiffness affects DNA folding hysteresis and stability.

Findings

Hysteresis observed in DNA conformations during folding and unfolding.

Stiffer chains exhibit more pronounced hysteresis loops.

Globular state is thermodynamically more stable within the hysteresis loop.

Abstract

The conformational behavior of a giant DNA mediated by condensing agents in the bulk solution has been investigated through experimental and theoretical approaches. Experimentally, a pronounced conformational hysteresis is observed for folding and unfolding processes, by increasing and decreasing the concentration of condensing agent PEG (Polyethylene glycol), respectively. To elucidate the observed hysteresis, a semiflexible chain model is studied by using Monte Carlo simulations for the coil-globule transition. In the simulations, the hysteresis loop emerges for stiff enough chains, indicating distinct pathways for folding and unfolding processes. Also, our results show that globular state is thermodynamically more stable than coiled state in the hysteresis loop. Our findings suggest that increasing chain stiffness may reduce the chain conformations relevant to the folding pathway, which impedes the folding process.