Structural highlights
Function
[CAPSD_FHV] Capsid protein alpha self-assembles to form an icosahedral procapsid with a T=3 symmetry, about 30 nm in diameter, and consisting of 60 capsid proteins trimers. In addition, 240 calcium ions are incorporated per capsid during assembly. The capsid encapsulates the two genomic RNAs. Capsid maturation occurs via autoproteolytic cleavage of capsid protein alpha generating capsid protein beta and the membrane-active peptide gamma. Peptide gamma: membrane-permeabilizing peptide produced by virus maturation, thereby creating the infectious virion. After endocytosis into the host cell, peptide gamma is probably exposed in endosomes, where it permeabilizes the endosomal membrane, facilitating translocation of viral capsid or RNA into the cytoplasm (Probable).
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
Divalent metal ions are components of numerous icosahedral virus capsids. Flock House virus (FHV), a small RNA virus of the family Nodaviridae, was utilized as an accessible model system with which to address the effects of metal ions on capsid structure and on the biology of virus-host interactions. Mutations at the calcium-binding sites affected FHV capsid stability and drastically reduced virus infectivity, without altering the overall architecture of the capsid. The mutations also altered the conformation of gamma, a membrane-disrupting, virus-encoded peptide usually sequestered inside the capsid, by increasing its exposure under neutral pH conditions. Our data demonstrate that calcium binding is essential for maintaining a pH-based control on gamma exposure and host membrane disruption, and they reveal a novel rationale for the metal ion requirement during virus entry and infectivity. In the light of the phenotypes displayed by a calcium site mutant of FHV, we suggest that this mutant corresponds to an early entry intermediate formed in the endosomal pathway.
Structure and function of a genetically engineered mimic of a nonenveloped virus entry intermediate.,Banerjee M, Speir JA, Kwan MH, Huang R, Aryanpur PP, Bothner B, Johnson JE J Virol. 2010 May;84(9):4737-46. Epub 2010 Feb 17. PMID:20164221[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Banerjee M, Speir JA, Kwan MH, Huang R, Aryanpur PP, Bothner B, Johnson JE. Structure and function of a genetically engineered mimic of a nonenveloped virus entry intermediate. J Virol. 2010 May;84(9):4737-46. Epub 2010 Feb 17. PMID:20164221 doi:10.1128/JVI.02670-09
