Packaging stiff polymers in small containers: A molecular dynamics study

TL;DR

This study uses molecular dynamics simulations to explore how stiff polymers, like DNA, pack into small viral capsids, revealing a tendency to form coaxial spools without twisting as rigidity increases.

Contribution

It demonstrates how increased polymer stiffness leads to spool-like packing arrangements in viral capsids, extending previous models with longer polymers and new packing configurations.

Findings

Stiffer polymers tend to form coaxial spools.

Polymer packing can occur without twisting.

Longer polymers exhibit similar spool formation tendencies.

Abstract

The question of how stiff polymers are able to pack into small containers is particularly relevant to the study of DNA packaging in viruses. A reduced version of the problem based on coarse-grained representations of the main components of the system -- the DNA polymer and the spherical viral capsid -- has been studied by molecular dynamics simulation. The results, involving longer polymers than in earlier work, show that as polymers become more rigid there is an increasing tendency to self-organize as spools that wrap from the inside out, rather than the inverse direction seen previously. In the final state, a substantial part of the polymer is packed into one or more coaxial spools, concentrically layered with different orientations, a form of packaging achievable without twisting the polymer.