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==Feline Calicivirus Strain F9 bound to a soluble ectodomain fragment of feline junctional adhesion molecule A - leading to assembly of a portal structure at a unique three-fold axis.==
<StructureSection load='6gsi' size='340' side='right'caption='[[6gsi]], [[Resolution|resolution]] 3.75&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6gsi]] is a 12 chain structure with sequence from [http://en.wikipedia.org/wiki/Cat Cat] and [http://en.wikipedia.org/wiki/Feline_calicivirus_strain_f9 Feline calicivirus strain f9]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6GSI OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6GSI FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=K:POTASSIUM+ION'>K</scene></td></tr>
<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[6gsh|6gsh]]</td></tr>
<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">F11R, JAM1 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=9685 Cat])</td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6gsi FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6gsi OCA], [http://pdbe.org/6gsi PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=6gsi RCSB], [http://www.ebi.ac.uk/pdbsum/6gsi PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=6gsi ProSAT]</span></td></tr>
</table>
== Function ==
[[http://www.uniprot.org/uniprot/CAPSD_FCVF9 CAPSD_FCVF9]] 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. [[http://www.uniprot.org/uniprot/VP2_FCVF9 VP2_FCVF9]] Minor structural protein present in one or two copies per virion. Does not seem to play a role in capsid assembly, but is essential for production of infectious virus (By similarity). [[http://www.uniprot.org/uniprot/JAM1_FELCA JAM1_FELCA]] Seems to play a role in epithelial tight junction formation. Appears early in primordial forms of cell junctions and recruits PARD3. The association of the PARD6-PARD3 complex may prevent the interaction of PARD3 with JAM1, thereby preventing tight junction assembly. Plays a role in regulating monocyte transmigration involved in integrity of epithelial barrier. Ligand for integrin alpha-L/beta-2 involved in memory T-cell and neutrophil transmigration. Involved in platelet activation.[UniProtKB:O88792][UniProtKB:Q9Y624]  (Microbial infection) May act as a cellular receptor for calicivirus.<ref>PMID:16611908</ref> <ref>PMID:17913818</ref>   (Microbial infection) In case of orthoreovirus infection, serves as receptor for the virus.<ref>PMID:11239401</ref>  
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
To initiate infection, many viruses enter their host cells by triggering endocytosis following receptor engagement. However, the mechanisms by which non-enveloped viruses escape the endosome are poorly understood. Here we present near-atomic-resolution cryo-electron microscopy structures for feline calicivirus both undecorated and labelled with a soluble fragment of its cellular receptor, feline junctional adhesion molecule A. We show that VP2, a minor capsid protein encoded by all caliciviruses(1,2), forms a large portal-like assembly at a unique three-fold axis of symmetry, following receptor engagement. This assembly-which was not detected in undecorated virions-is formed of twelve copies of VP2, arranged with their hydrophobic N termini pointing away from the virion surface. Local rearrangement at the portal site leads to the opening of a pore in the capsid shell. We hypothesize that the portal-like assembly functions as a channel for the delivery of the calicivirus genome, through the endosomal membrane, into the cytoplasm of a host cell, thereby initiating infection. VP2 was previously known to be critical for the production of infectious virus(3); our findings provide insights into its structure and function that advance our understanding of the Caliciviridae.

Calicivirus VP2 forms a portal-like assembly following receptor engagement.,Conley MJ, McElwee M, Azmi L, Gabrielsen M, Byron O, Goodfellow IG, Bhella D Nature. 2019 Jan;565(7739):377-381. doi: 10.1038/s41586-018-0852-1. Epub 2019 Jan, 9. PMID:30626974<ref>PMID:30626974</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 6gsi" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Cat]]
[[Category: Feline calicivirus strain f9]]
[[Category: Large Structures]]
[[Category: Bhella, D]]
[[Category: Conley, M J]]
[[Category: Calicivirus]]
[[Category: Capsid]]
[[Category: Junctional-adhesion molecule some]]
[[Category: Portal]]
[[Category: Vesivirus]]
[[Category: Virus]]
[[Category: Vp1]]
[[Category: Vp2]]