Solution scattering studies on a virus capsid protein as a building block for nanoscale assemblies

Abstract

Self-assembled protein cages are versatile building blocks in the construction of biomolecular nanostructures. Because of the defined assembly behaviour the cowpea chlorotic mottle virus (CCMV) protein is often used for such applications. Here we report a detailed solution scattering study of the CCMV virus and empty capsid. Contrast variation in small-angle neutron scattering (SANS) reveals a well-defined protein shell, with RNA associated mainly with its inner surface. The empty capsid has a protein shell with a diameter comparable to that of the virus, and has some weak scattering density associated on the inside, presumably the N-terminal part which is involved in RNA binding. Dynamic light scattering (DLS) and SANS show that the virus swells with increasing pH (5.0 to 7.5), whereas the empty capsid disassembles; the aggregation behaviour of the capsid protein becomes more complex at salt concentrations below 0.5 M NaCl. Incorporation of polystyrene sulfonate (PSS) in the capsid gives a particle with a solvent core, a polymer inner shell, and a protein outer shell, with a much smaller capsid outer diameter.

Self-assembly and characterization of small and monodisperse dye nanospheres in a protein cage

“…The presence of two particle sizes is probably due to CP conformational exibility, and differs from dynamic swelling of the CCMV capsid, which produces larger size changes (i.e., ca. 5%) 47 in comparison to the present case (i.e., ca. 1%).…”

Icosahedral capsid formation by capsomers and short polyions

“…For example, the co-assembly can be very sensitive to ambient conditions such as pH and ionic strength. In recent years, increasing efforts have been paid to theoretical and experimental investigations of the capsid self-assembly, 14,[30][31][32][33][34][35][36][37][38][39][40] especially studies of the influence of spherical [41][42][43][44] or chain-like [45][46][47][48] cargos on the virus capsid formation.…”

Plant molecular farming of virus‐like nanoparticles as vaccines and reagents

“…By the 1990s, in vitro assembly of CP expressed in Escherichia coli and viral RNAs transcribed from cDNA had been shown (Zhao, Fox, Olson, Baker, & Young, 1995), as well as the apparent structural identity of artificial and natural virions (Fox et al, 1998). By the 2000s, yeast-made Gd 3+ -infused CCMV VNPs were being investigated as magnetic resonance contrast agents (Allen et al, 2005), and interest in both virions and VNPs has continued (Comellas-Aragones et al, 2011;Lavelle, Michel, & Gingery, 2007;Schoonen, Maas, Nolte, & van Hest, 2017;Suci, Klem, Arce, Douglas, & Young, 2006;Torres-Salgado et al, 2016). Interestingly, while it is assumed that the surface structure of CCMV and other generic bromovirus capsids is essentially identical to the native virions, a serological study in 1983 showed quantifiable antigenic differences by means of enzyme-linked immunosorbent assay between brome mosaic bromovirus virions and empty capsids (Rybicki & Coyne, 1983).…”