Speaker
Description
The genetic code of viruses, RNA or DNA, are typically protected in an icosahedral capsid, which is primarily
assembled from over a hundred subunits of the same protein in a spontaneous self-assembly process. Similar
highly efficient assembly processes are ubiquitous in biological systems; viral capsids present a unique platform
to exploit for therapeutic advances in the targeted cellular delivery of cargo packaged within the capsid.
Our research aims to provide a more detailed understanding of how this precise viral capsid protein assembly
process occurs from a pool of single building blocks, and additionally the effect and organization of nucleic
acid present during assembly. Here, we present results from small-angle neutron scattering experiments using
contrast variation to reveal the final assembled structural organization of both the protein and nucleic
acid components from recombinant Hepatitis B virus (HBV) capsid protein and a synthetically prepared RNA
containing the capsid protein binding domain. These data revealed that RNA was localized along the inner capsid
surface. Time-resolved small-angle x-ray scattering (SAXS) experiments were also used to determine the
structure during HBV capsid assembly in the presence and absence of RNA. We employed Bayesian statisticsbased
computational methods to extract kinetic parameters of assembly and the overall size and shape of the
dominant structural intermediates from the SAXS data. Additional single-particle cryoEM reconstructions are
provided to assess the effect of RNA on the resulting assembled capsid structure. The combination of timeresolved
scattering data, Bayesian statistics, and cryoEM structural analysis, provides a framework which not
only describes the viral self-assembly process, but can be extended to other hierarchical assemblies in biology.
