How does torsional rigidity affect the wrapping transition of a semiflexible chain around a spherical core?

TL;DR

This study uses molecular dynamics simulations to explore how torsional rigidity influences the wrapping behavior of semiflexible chains around spherical cores, revealing critical effects on transition dynamics and structure.

Contribution

It demonstrates the significant role of torsional stress in chain wrapping transitions and the formation of unique wrapping structures under topological constraints.

Findings

Torsional stress induces wrapping/unwrapping transitions.

Unique antagonistic wrapping structures emerge with torsional constraints.

Torsional effects differ under stretching stress conditions.

Abstract

We investigated the effect of torsional rigidity of a semiflexible chain on the wrapping transition around a spherical core, as a model of nucleosome, the fundamental unit of chromatin. Through molecular dynamics simulation, we show that the torsional effect has a crucial effect on the chain wrapping around the core under the topological constraints. In particular, the torsional stress (i) induces the wrapping/unwrapping transition, and (ii) leads to a unique complex structure with an antagonistic wrapping direction which never appears without the topological constraints. We further examine the effect of the stretching stress for the nucleosome model, in relation to the unique characteristic effect of the torsional stress on the manner of wrapping.