90 research outputs found
DNA duplex cage structures with icosahedral symmetry
A construction method for duplex cage structures with icosahedral symmetry made out of single-stranded DNA molecules is presented and applied to an icosidodecahedral cage. It is shown via a mixture of analytic and computer techniques that there exist realisations of this graph in terms of two circular DNA molecules. These blueprints for the organisation of a cage structure with a noncrystallographic symmetry may assist in the design of containers made from DNA for applications in nanotechnology
Protein container disassembly pathways depend on geometric design
The majority of viruses are organised according to the structural blueprints
of the seminal Caspar-Klug theory. However, there are a number of notable
exceptions to this geometric design principle. Prominent examples are the
cancer-causing papilloma viridae and the \textit{de novo} designed AaLS cages
that exhibit non-quasiequivalent capsid structures with protein numbers
excluded by Caspar-Klug theory. The biophysical properties of these
geometrically distinct architectures and the fitness advantages driving their
evolution are currently unclear. We investigate here the resilience to
fragmentation and disassembly behaviour of these capsid geometries by
introducing a percolation theory on weighted graphs. We show that these cage
architectures follow one of two distinct disassembly pathways, preferring
either hole formation or capsid fragmentation. This suggests that preference
for specific disassembly scenarios could be a driving force for the evolution
of the non Caspar-Klug protein container architectures.Comment: 15 pages, 10 figure
Dynamical implications of Viral Tiling Theory
The Caspar–Klug classification of viruses whose protein shell, called viral capsid, exhibits icosahedral symmetry, has recently been extended to incorporate viruses whose capsid proteins are exclusively organised in pentamers. The approach, named ‘Viral Tiling Theory’, is inspired by the theory of quasicrystals, where aperiodic Penrose tilings enjoy 5-fold and 10-fold local symmetries. This paper analyses the extent to which this classification approach informs dynamical properties of the viral capsids, in particular the pattern of Raman active modes of vibrations, which can be observed experimentally
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