Helical Disruptions in Small Loops of DNA

TL;DR

This paper uses path integral techniques to study how small circular DNA molecules experience helix disruptions due to thermal fluctuations, revealing size-dependent mechanisms that facilitate biological functions like transcription.

Contribution

It introduces a novel application of path integral methods to analyze the stability and disruption patterns in small DNA loops, highlighting size effects on helix unwinding.

Findings

Helix disruptions occur in DNA minicircles with fewer than 100 base pairs.

Disruptions serve as a stress-relief mechanism for bending and torsion.

Size influences the likelihood and pattern of helix unwinding.

Abstract

The thermodynamical stability of DNA minicircles is investigated by means of path integral techniques. Hydrogen bonds between base pairs on complementary strands can be broken by thermal fluctuations and temporary fluctuational openings along the double helix are essential to biological functions such as transcription and replication of the genetic information. Helix unwinding and bubble formation patterns are computed in circular sequences with variable radius in order to analyze the interplay between molecule size and appearance of helical disruptions. The latter are found in minicircles with $< 100$ base pairs and appear as a strategy to soften the stress due to the bending and torsion of the helix.