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From Proteopedia
X-ray structure of a native calicivirus
Structural highlights
Function[CAPSD_SMSV4] Capsid protein self assembles to form an icosahedral capsid with a T=3 symmetry, about 38 nm in diameter, and consisting of 180 capsid proteins. A smaller form of capsid with a diameter of 23 nm might be capsid proteins assembled as icosahedron with T=1 symmetry. The capsid encapsulate the genomic RNA and VP2 proteins. Attaches virion to target cells by binding to feline junctional adhesion molecule A (F11R) and/or to alpha-2,6-linked sialic acid. Once attached, the virion is endocytosed. Acidification of the endosome induces conformational change of capsid protein thereby injecting virus genomic RNA into host cytoplasm (By similarity). Evolutionary Conservation Checkto colour the structure by Evolutionary Conservation, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedCaliciviruses, grouped into four genera, are important human and veterinary pathogens with a potential for zoonosis. In these viruses, capsid-related functions such as assembly, antigenicity, and receptor interactions are predominantly encoded in a single protein that forms an icosahedral capsid. Understanding of the immunologic functions and pathogenesis of human caliciviruses in the Norovirus and Sapovirus genera is hampered by the lack of a cell culture system or animal models. Much of our understanding of these viruses, including the structure, has depended on recombinant capsids. Here we report the atomic structure of a native calicivirus from the Vesivirus genus that exhibits a broad host range possibly including humans and map immunological function onto a calicivirus structure. The vesivirus structure, despite a similar architectural design as seen in the recombinant norovirus capsid, exhibits novel features and indicates how the unique modular organization of the capsid protein with interdomain flexibility, similar to an antibody structure with a hinge and an elbow, integrates capsid-related functions and facilitates strain diversity in caliciviruses. The internally located N-terminal arm participates in a novel network of interactions through domain swapping to assist the assembly of the shell domain into an icosahedral scaffold, from which the protruding domain emanates. Neutralization epitopes localize to three hypervariable loops in the distal portion of the protruding domain surrounding a region that exhibits host-specific conservation. These observations suggest a mechanism for antigenic diversity and host specificity in caliciviruses and provide a structural framework for vaccine development. X-ray structure of a native calicivirus: structural insights into antigenic diversity and host specificity.,Chen R, Neill JD, Estes MK, Prasad BV Proc Natl Acad Sci U S A. 2006 May 23;103(21):8048-53. Epub 2006 May 15. PMID:16702551[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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