"Local rules" theory applied to polyomavirus polymorphic capsid assemblies

The papovaviruses are nonenveloped dsDNA viruses whose capsids are characte rized by a non-quasi-equivalent bonding pattern in which 72 pentameric caps omeres occupy positions having either five or six neighboring capsomeres. T he local rules theory of Berger et ai. (1994, Proc. Natl. Acad. Sci. USA, 9 1, 7732-7736), previously developed to explain aspects of icosahedral capsi d assembly, has been applied to the papovavirus geometry. Local rules descr ibe capsid symmetry patterns in terms of the local interactions of assembly units, such as coat proteins or capsomeres. Polymorphic assemblies, includ ing T = 1 icosahedral, dodecahedral, spiral, and tubular structures of the polyomavirus VP1 protein, can be induced by specific mutations or changes i n the solvent conditions during in vitro assembly of the recombinant coat p rotein. Local rules models were developed to model the wild-type capsid and several polymorphic assemblies. Some assemblies corresponded to structures modeled by small deviations from wild-type local rules. We conclude that a spects of polyomavirus assembly are consistent with local rules models, alt hough they do not explain all polymorphisms. These results may provide insi ghts into the nature of papovavirus assembly, constraints on assembly pathw ays, and strategies for disrupting assembly. (C) 2000 Academic Press.