3iys | pdb_00003iys
Homology model of avian polyomavirus asymmetric unit
Structural highlights
Function[VP1_BFPYV] Forms an icosahedral capsid with a T=7 symmetry and a 46-48 nm diameter. The capsid is composed of 72 pentamers linked to each other by disulfide bonds and associated with VP2 or VP3 proteins. Interacts with sialic acids on the cell surface to provide virion attachment to target cell. Once attached, the virion is internalized by endocytosis and traffics to the endoplasmic reticulum. Inside the endoplasmic reticulum, the protein folding machinery isomerizes VP1 interpentamer disulfide bonds, thereby triggering initial uncoating. Next, the virion uses the endoplasmic reticulum-associated degradation machinery to probably translocate in the cytosol before reaching the nucleus. Nuclear entry of the viral DNA involves the selective exposure and importin recognition of VP2/Vp3 nuclear localization signal. In late phase of infection, neo-synthesized VP1 encapsulates replicated genomic DNA in the nucleus, and participates in rearranging nucleosomes around the viral DNA (By similarity). Publication Abstract from PubMedAvian polyomavirus (APV) causes a fatal, multi-organ disease among several bird species. Using cryogenic electron microscopy and other biochemical techniques, we investigated the structure of APV and compared it to that of mammalian polyomaviruses, particularly JC polyomavirus and simian virus 40. The structure of the pentameric major capsid protein (VP1) is mostly conserved; however, APV VP1 has a unique, truncated C-terminus that eliminates an intercapsomere-connecting beta-hairpin observed in other polyomaviruses. We postulate that the terminal beta-hairpin locks other polyomavirus capsids in a stable conformation and that absence of the hairpin leads to the observed capsid size variation in APV. Plug-like density features were observed at the base of the VP1 pentamers, consistent with the known location of minor capsid proteins VP2 and VP3. However, the plug density is more prominent in APV and may include VP4, a minor capsid protein unique to bird polyomaviruses. The structure of avian polyomavirus reveals variably sized capsids, non-conserved inter-capsomere interactions, and a possible location of the minor capsid protein VP4.,Shen PS, Enderlein D, Nelson CD, Carter WS, Kawano M, Xing L, Swenson RD, Olson NH, Baker TS, Cheng RH, Atwood WJ, Johne R, Belnap DM Virology. 2011 Jan 14. PMID:21239031[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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