Localization of the C terminus of the assembly domain of hepatitis B virus capsid protein: Implications for morphogenesis and organization of encapsidated RNA

摘要

The capsid protein of hepatitis B virus, con- sisting of an "assembly" domain (residues 1-149) and an RNA-binding "protamine" domain (residues 150-183), as- sembles from dimers into icosahedral capsids of two different sizes. The C terminus of the assembly domain (residues 140-149) functions as a morphogenetic switch, longer C termini favoring a higher proportion of the larger capsids, it also connects the protamine domain to the capsid shell. We now have defined the location of this peptide in capsids assembled in vitro by engineering a mutant assembly domain with a single cysteine at its C terminus (residue 150), labeling it with a gold cluster and visualizing the cluster by cryo- electron microscopy.