THE STRUCTURE OF SATELLITE PANICUM MOSAIC-VIRUS AT 1.9 ANGSTROM RESOLUTION

The crystal structure of satellite panicum mosaic virus (SPMV) has bee n solved by multiple isomorphous replacement and molecular replacement and refined at 1.9 Angstrom resolution. SPMV, a T=1 icosahedral virus , is the smallest virus structure determined. The coat protein is an e ight-stranded 'jelly roll' beta-barrel with an amino-terminal strand t hat extends into the interior of the virus, presumably interacting wit h the RNA. Regions of electron density on the interior of the protein capsid may be RNA, although it is not possible to construct any detail ed model of the nucleic acid. Basic amino acid residues in contact wit h the nucleic acid show a considerable degree of disorder. The carboxy -terminal strand of the virus coat protein interacts with adjacent sub units, forming an additional beta-strand.