Encapsulation of a polymer by an icosahedral virus

TL;DR

This study uses coarse-grained Brownian dynamics simulations to explore how polymers are encapsulated by icosahedral virus capsids, revealing mechanisms and parameters influencing assembly efficiency.

Contribution

It introduces a simulation framework that elucidates polymer roles and predicts assembly outcomes, aiding in designing virus capsid assembly experiments.

Findings

Polymer actively influences capsid assembly through cooperative motions.

Assembly efficiency depends on polymer length, protein concentration, and solution conditions.

A phase diagram predicts assembly outcomes based on experimental parameters.

Abstract

The coat proteins of many viruses spontaneously form icosahedral capsids around nucleic acids or other polymers. Elucidating the role of the packaged polymer in capsid formation could promote biomedical efforts to block viral replication and enable use of capsids in nanomaterials applications. To this end, we perform Brownian dynamics on a coarse-grained model that describes the dynamics of icosahedral capsid assembly around a flexible polymer. We identify several mechanisms by which the polymer plays an active role in its encapsulation, including cooperative polymer-protein motions. These mechanisms are related to experimentally controllable parameters such as polymer length, protein concentration, and solution conditions. Furthermore, the simulations demonstrate that assembly mechanisms are correlated to encapsulation efficiency, and we present a phase diagram that predicts assembly outcomes as a function of experimental parameters. We anticipate that our simulation results will provide a framework for designing in vitro assembly experiments on single-stranded RNA virus capsids.