Helicase on DNA: A Phase coexistence based mechanism

TL;DR

This paper introduces a phase coexistence mechanism to explain helicase activity, where the enzyme shifts a domain wall between zipped and unzipped DNA regions, providing a new physical perspective on DNA unwinding.

Contribution

It presents a novel phase coexistence model for helicase function, linking domain wall dynamics to DNA unwinding activity, which is a new theoretical approach.

Findings

The model explains key features of helicase activity.

Domain wall motion correlates with DNA unzipping.

Provides a physical basis for helicase mechanism.

Abstract

We propose a phase coexistence based mechanism for activity of helicases, ubiquitous enzymes that unwind double stranded DNA. The helicase-DNA complex constitutes a fixed-stretch ensemble that entails a coexistence of domains of zipped and unzipped phases of DNA, separated by a domain wall. The motor action of the helicase leads to a change in the position of the fixed constraint thereby shifting the domain wall on dsDNA. We associate this off-equilibrium domain wall motion with the unzipping activity of helicase. We show that this proposal gives a clear and consistent explanation of the main observed features of helicases.