View source for 6i2k


==Structure of EV71 complexed with its receptor SCARB2==
<SX load='6i2k' size='340' side='right' viewer='molstar' caption='[[6i2k]], [[Resolution|resolution]] 3.40&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6i2k]] is a 5 chain structure with sequence from [https://en.wikipedia.org/wiki/Enterovirus_A71 Enterovirus A71] and [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6I2K OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6I2K FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Electron Microscopy, [[Resolution|Resolution]] 3.4&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=906:1-(2-AMINOPYRIDIN-4-YL)-3-[(3S)-5-{4-[(E)-(ETHOXYIMINO)METHYL]PHENOXY}-3-METHYLPENTYL]IMIDAZOLIDIN-2-ONE'>906</scene>, <scene name='pdbligand=BMA:BETA-D-MANNOSE'>BMA</scene>, <scene name='pdbligand=MAN:ALPHA-D-MANNOSE'>MAN</scene>, <scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=6i2k FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6i2k OCA], [https://pdbe.org/6i2k PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6i2k RCSB], [https://www.ebi.ac.uk/pdbsum/6i2k PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6i2k ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/POLG_HE71M POLG_HE71M] Forms an icosahedral capsid of pseudo T=3 symmetry with capsid proteins VP2 and VP3 (By similarity). The capsid is 300 Angstroms in diameter, composed of 60 copies of each capsid protein and enclosing the viral positive strand RNA genome (By similarity). Capsid protein VP1 mainly forms the vertices of the capsid (By similarity). Capsid protein VP1, together with VP2, interacts with host cell receptor SCARB2 to provide virion attachment to target host cells (PubMed:30531980). This attachment induces virion internalization (By similarity). After binding to its receptor, the capsid undergoes conformational changes (By similarity). Capsid protein VP1 N-terminus (that contains an amphipathic alpha-helix) and capsid protein VP4 are externalized (By similarity). Together, they shape a pore in the host membrane through which viral genome is translocated to host cell cytoplasm (By similarity).[UniProtKB:P03300]<ref>PMID:30531980</ref>   Forms an icosahedral capsid of pseudo T=3 symmetry with capsid proteins VP2 and VP3 (By similarity). The capsid is 300 Angstroms in diameter, composed of 60 copies of each capsid protein and enclosing the viral positive strand RNA genome (By similarity). Capsid protein VP2, together with VP1, interacts with host cell receptor SCARB2 to provide virion attachment to target host cells (PubMed:30531980).[UniProtKB:P03300]<ref>PMID:30531980</ref>   Forms an icosahedral capsid of pseudo T=3 symmetry with capsid proteins VP2 and VP3 (By similarity). The capsid is 300 Angstroms in diameter, composed of 60 copies of each capsid protein and enclosing the viral positive strand RNA genome (By similarity).[UniProtKB:P03300]  Lies on the inner surface of the capsid shell (By similarity). After binding to the host receptor, the capsid undergoes conformational changes (By similarity). Capsid protein VP4 is released, Capsid protein VP1 N-terminus is externalized, and together, they shape a pore in the host membrane through which the viral genome is translocated into the host cell cytoplasm (By similarity).[UniProtKB:P03300]  Component of immature procapsids, which is cleaved into capsid proteins VP4 and VP2 after maturation (By similarity). Allows the capsid to remain inactive before the maturation step (By similarity).[UniProtKB:P03300]  Cysteine protease that cleaves viral polyprotein and specific host proteins (By similarity). It is responsible for the autocatalytic cleavage between the P1 and P2 regions, which is the first cleavage occurring in the polyprotein (By similarity). Cleaves also the host translation initiation factor EIF4G1, in order to shut down the capped cellular mRNA translation (By similarity). Inhibits the host nucleus-cytoplasm protein and RNA trafficking by cleaving host members of the nuclear pores (By similarity). Counteracts stress granule formation probably by antagonizing its assembly or promoting its dissassembly (By similarity). Cleaves and inhibits host IFIH1/MDA5, thereby inhibiting the type-I IFN production and the establishment of the antiviral state (By similarity). Cleaves and inhibits host MAVS, thereby inhibiting the type-I IFN production and the establishment of the antiviral state (By similarity).[UniProtKB:P03300][UniProtKB:Q66478]  Plays an essential role in the virus replication cycle by acting as a viroporin. Creates a pore in the host reticulum endoplasmic and as a consequence releases Ca2+ in the cytoplasm of infected cell. In turn, high levels of cytoplasmic calcium may trigger membrane trafficking and transport of viral ER-associated proteins to viroplasms, sites of viral genome replication.[UniProtKB:P03300]  Induces and associates with structural rearrangements of intracellular membranes. Displays RNA-binding, nucleotide binding and NTPase activities. May play a role in virion morphogenesis and viral RNA encapsidation by interacting with the capsid protein VP3.[UniProtKB:P03300]  Localizes the viral replication complex to the surface of membranous vesicles. Together with protein 3CD binds the Cis-Active RNA Element (CRE) which is involved in RNA synthesis initiation. Acts as a cofactor to stimulate the activity of 3D polymerase, maybe through a nucleid acid chaperone activity.[UniProtKB:P03300]  Localizes the viral replication complex to the surface of membranous vesicles (By similarity). It inhibits host cell endoplasmic reticulum-to-Golgi apparatus transport and causes the disassembly of the Golgi complex, possibly through GBF1 interaction (By similarity). This would result in depletion of MHC, trail receptors and IFN receptors at the host cell surface (By similarity). Plays an essential role in viral RNA replication by recruiting ACBD3 and PI4KB at the viral replication sites, thereby allowing the formation of the rearranged membranous structures where viral replication takes place (Probable).[UniProtKB:P03300]<ref>PMID:31381608</ref>   Acts as a primer for viral RNA replication and remains covalently bound to viral genomic RNA. VPg is uridylylated prior to priming replication into VPg-pUpU (By similarity). The oriI viral genomic sequence may act as a template for this. The VPg-pUpU is then used as primer on the genomic RNA poly(A) by the RNA-dependent RNA polymerase to replicate the viral genome (By similarity). Following genome release from the infecting virion in the cytoplasm, the VPg-RNA linkage is probably removed by host TDP2 (By similarity). During the late stage of the replication cycle, host TDP2 is excluded from sites of viral RNA synthesis and encapsidation, allowing for the generation of progeny virions (By similarity).[UniProtKB:P03300]  Involved in the viral replication complex and viral polypeptide maturation. It exhibits protease activity with a specificity and catalytic efficiency that is different from protease 3C. Protein 3CD lacks polymerase activity. Protein 3CD binds to the 5'UTR of the viral genome.[UniProtKB:P03300]  Major viral protease that mediates proteolytic processing of the polyprotein (By similarity). Cleaves host EIF5B, contributing to host translation shutoff (By similarity). Cleaves also host PABPC1, contributing to host translation shutoff (By similarity). Disassembles host cytoplasmic stress granules by cleaving host G3BP1, although this effect is less prononced than the inhibition induced by protease 2A (By similarity). Cleaves host RIGI and thus contributes to the inhibition of type I interferon production (By similarity). Cleaves host IRF7 and thus contributes to the inhibition of type I interferon production (By similarity). Cleaves host HNRNPA1 thereby increasing the translation of apoptosis protease activating factor APAF1, leading to apoptosis of the host cell (By similarity). Cleaves host NLRP1, triggers host N-glycine-mediated degradation of the autoinhibitory NLRP1 N-terminal fragment (By similarity).[UniProtKB:P03300][UniProtKB:P03303][UniProtKB:Q66478]  Replicates the viral genomic RNA on the surface of intracellular membranes. May form linear arrays of subunits that propagate along a strong head-to-tail interaction called interface-I. Covalently attaches UMP to a tyrosine of VPg, which is used to prime RNA synthesis. The positive stranded RNA genome is first replicated at virus induced membranous vesicles, creating a dsRNA genomic replication form. This dsRNA is then used as template to synthesize positive stranded RNA genomes. ss(+)RNA genomes are either translated, replicated or encapsidated.[UniProtKB:P03300]
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== Publication Abstract from PubMed ==
Enterovirus 71 (EV71) is a common cause of hand, foot and mouth disease-a disease endemic especially in the Asia-Pacific region(1). Scavenger receptor class B member 2 (SCARB2) is the major receptor of EV71, as well as several other enteroviruses responsible for hand, foot and mouth disease, and plays a key role in cell entry(2). The isolated structures of EV71 and SCARB2 are known(3-6), but how they interact to initiate infection is not. Here, we report the EV71-SCARB2 complex structure determined at 3.4 A resolution using cryo-electron microscopy. This reveals that SCARB2 binds EV71 on the southern rim of the canyon, rather than across the canyon, as predicted(3,7,8). Helices 152-163 (alpha5) and 183-193 (alpha7) of SCARB2 and the viral protein 1 (VP1) GH and VP2 EF loops of EV71 dominate the interaction, suggesting an allosteric mechanism by which receptor binding might facilitate the low-pH uncoating of the virus in the endosome/lysosome. Remarkably, many residues within the binding footprint are not conserved across SCARB2-dependent enteroviruses; however, a conserved proline and glycine seem to be key residues. Thus, although the virus maintains antigenic variability even within the receptor-binding footprint, the identification of binding 'hot spots' may facilitate the design of receptor mimic therapeutics less likely to quickly generate resistance.

Unexpected mode of engagement between enterovirus 71 and its receptor SCARB2.,Zhou D, Zhao Y, Kotecha A, Fry EE, Kelly JT, Wang X, Rao Z, Rowlands DJ, Ren J, Stuart DI Nat Microbiol. 2018 Dec 10. pii: 10.1038/s41564-018-0319-z. doi:, 10.1038/s41564-018-0319-z. PMID:30531980<ref>PMID:30531980</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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== References ==
<references/>
__TOC__
</SX>
[[Category: Enterovirus A71]]
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Fry EE]]
[[Category: Kelly J]]
[[Category: Kotecha A]]
[[Category: Rao Z]]
[[Category: Ren J]]
[[Category: Rowlands DJ]]
[[Category: Stuart DI]]
[[Category: Wang X]]
[[Category: Zhao Y]]
[[Category: Zhou D]]