Periodic table of virus capsids: implications for natural selection and design.
BACKGROUND
For survival, most natural viruses depend upon the existence of spherical capsids: protective shells of various sizes composed of protein subunits. So far, general evolutionary pressures shaping capsid design have remained elusive, even though an understanding of such properties may help in rationally impeding the virus life cycle and designing efficient nano-assemblies.


RESULTS
This report uncovers an unprecedented and species-independent evolutionary pressure on virus capsids, based on the the notion that the simplest capsid designs (or those capsids with the lowest "hexamer complexity", C(h)) are the fittest, which was shown to be true for all available virus capsids. The theories result in a physically meaningful periodic table of virus capsids that uncovers strong and overarching evolutionary pressures, while also offering geometric explanations to other capsid properties (rigidity, pleomorphy, auxiliary requirements, etc.) that were previously considered to be unrelatable properties of the individual virus.


CONCLUSIONS
Apart from describing a universal rule for virus capsid evolution, our work (especially the periodic table) provides a language with which highly diverse virus capsids, unified only by geometry, may be described and related to each other. Finally, the available virus structure databases and other published data reiterate the predicted geometry-derived rules, reinforcing the role of geometry in the natural selection and design of virus capsids.
Mannige
Ranjan V
RV
Department of Chemistry and Biophysics Program, University of Michigan, Ann Arbor, Michigan, United States of America. ranjan@umich.edu
Brooks
Charles L
CL
D002213:Capsid / Q000378:metabolism* / Q000502:physiology*; D018360:Crystallography, X-Ray / Q000379:methods; D008854:Microscopy, Electron / Q000379:methods; D015233:Models, Statistical; D053758:Nanoparticles / Q000737:chemistry; D036103:Nanotechnology / Q000379:methods; D012641:Selection, Genetic; D014764:Viral Proteins / Q000737:chemistry; D056224:Viral Structures; D014773:Virology / Q000379:methods; D019065:Virus Assembly; D014780:Viruses / Q000737:chemistry / Q000378:metabolism*
D014764:Viral Proteins