Role of electrostatic interactions in the assembly of empty spherical viral capsids

TL;DR

This paper investigates how electrostatic repulsion and angle-dependent attractive forces between protein subunits influence the formation of spherical viral capsids, highlighting the importance of curvature-dependent interactions.

Contribution

It demonstrates that curvature-dependent attractive interactions are essential for the assembly of viral capsids despite electrostatic repulsion.

Findings

Electrostatic interactions oppose capsid assembly.

Angle-dependent attractive forces facilitate preferred capsid radius.

Results align with experimental data on Hepatitis B virus protein contacts.

Abstract

We examine the role of electrostatic interactions in the assembly of empty spherical viral capsids. The charges on the protein subunits that make the viral capsid mutually interact and are expected to yield electrostatic repulsion acting against the assembly of capsids. Thus, attractive protein-protein interactions of non-electrostatic origin must act to enable the capsid formation. We investigate whether the interplay of repulsive electrostatic and attractive interactions between the protein subunits can result in the formation of spherical viral capsids of a preferred radius. For this to be the case, we find that the attractive interactions must depend on the angle between the neighboring protein subunits (i.e. on the mean curvature of the viral capsid) so that a particular angle(s) is (are) preferred energywise. Our results for the electrostatic contributions to energetics of viral capsids nicely correlate with recent experimental determinations of the energetics of protein-protein contacts in Hepatitis B virus [P. Ceres and A. Zlotnick, Biochemistry {\bf 41}, 11525 (2002).