Minimal Design Principles for Icosahedral Virus Capsids
Fecha
2021Resumen
The geometrical structures of single- and multiple-shell icosahedral virus capsids are reproduced as the targets
that minimize the cost corresponding to relatively simple design
functions. Capsid subunits are first identified as building blocks
at a given coarse-grained scale and then represented in these
functions as point particles located on an appropriate number
of concentric spherical surfaces. Minimal design cost is assigned
to optimal spherical packings of the particles. The cost
functions are inspired by the packings favored for the Thomson
problem, which minimize the electrostatic potential energy between identical charged particles. In some cases, icosahedral symmetry constraints are incorporated as external fields acting on the particles. The simplest cost functions can be obtained by separating particles in disjoint nonequivalent sets with distinct interactions, or by introducing interacting holes (the absence of
particles). These functions can be adapted to reproduce any capsid structure found in real viruses. Structures absent in Nature require significantly more complex designs. Measures of information content and complexity are assigned to both the cost functions and the capsid geometries. In terms of these measures, icosahedral structures and the corresponding cost functions are the simplest solutions.