Structure of the reovirus core at 3.6?Å resolution

Abstract

The reovirus core is an assembly with a relative molecular mass of 52 million that synthesizes, modifies and exports viral messenger RNA. Analysis of its structure by X-ray crystallography shows that there are alternative, specific and completely non-equivalent contacts made by several surfaces of two of its proteins; that the RNA capping and export apparatus is a hollow cylinder, which probably sequesters its substrate to ensure completion of the capping reactions; that the genomic double-stranded RNA is coiled into concentric layers within the particle; and that there is a protein shell that appears to be common to all groups of double-stranded RNA viruses.

Inter-segment complementarity in orbiviruses: a driver for co-ordinated genome packaging in the Reoviridae?

“…4), demonstrates that the stability of the interaction between the motifs is important for their function. Therefore, RNA-RNA incompatibilities can be added to the already known protein-protein incompatibilities and protein-RNA incompatibilities which are believed to prevent the exchange of genome segments between different Orbivirus species, supporting a further functional underpinning for speciation in the genus (Grimes et al, 1998;Lawton et al, 1997;Modrof et al, 2005;Reinisch et al, 2000).…”

“…For the more highly segmented Reoviridae, a model similarly based on specific RNA-protein interactions may be considered unlikely as it would require up to 11 distinct intermediate binding specificities to be generated in the capsid. There is no evidence that such structurally distinct capsid variants exist amongst the known capsid structures of this family (Grimes et al, 1998;Lawton et al, 1997;Mindich, 1999;Nakagawa et al, 2003;Pesavento et al, 2006;Reinisch et al, 2000). Additionally, the highly reiterative nature of the structural proteins which define the architecture of the virus particle argues that they would be poor candidates for providing a unique copy of a binding site for each segment during genome packaging.…”

Structure of the bacteriophage φ29 DNA packaging motor

“…In contrast, the inside of the channel has a preponderance of negative charge at its wide end, which may repel the DNA, permitting its smooth passage during packaging and ejection. The channel through which messenger RNA is translocated in reoviruses has similar properties 18 .…”

Cryo-EM structure of a transcribing cypovirus

“…The capping enzymes in viruses of the subfamily Sedoreovirinae without turret structures are located under the fivefold vertex inside the capsid shell (2,12). A common process adopted by all Reoviridae members, and some other dsRNA viruses, is the uncoating of the outer capsid after delivery into the cytoplasm of host cells (13,14) prior to transcription, and the core remains intact and serves as a stable nano-scale machine for viral mRNA transcription and capping and for protecting the transcription process from the antiviral defense mechanisms of the host cell (12,(15)(16)(17).…”