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| | <StructureSection load='6xdc' size='340' side='right'caption='[[6xdc]], [[Resolution|resolution]] 2.90Å' scene=''> | | <StructureSection load='6xdc' size='340' side='right'caption='[[6xdc]], [[Resolution|resolution]] 2.90Å' scene=''> |
| | == Structural highlights == | | == Structural highlights == |
| - | <table><tr><td colspan='2'>[[6xdc]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/2019-ncov 2019-ncov]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6XDC OCA]. For a <b>guided tour on the structure components</b> use [http://proteopedia.org/fgij/fg.htm?mol=6XDC FirstGlance]. <br> | + | <table><tr><td colspan='2'>[[6xdc]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Severe_acute_respiratory_syndrome_coronavirus_2 Severe acute respiratory syndrome coronavirus 2]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6XDC OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6XDC FirstGlance]. <br> |
| - | </td></tr><tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">3a ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=2697049 2019-nCoV])</td></tr> | + | </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=6xdc FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6xdc OCA], [https://pdbe.org/6xdc PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6xdc RCSB], [https://www.ebi.ac.uk/pdbsum/6xdc PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6xdc ProSAT]</span></td></tr> |
| - | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://proteopedia.org/fgij/fg.htm?mol=6xdc FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6xdc OCA], [http://pdbe.org/6xdc PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=6xdc RCSB], [http://www.ebi.ac.uk/pdbsum/6xdc PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=6xdc ProSAT]</span></td></tr> | + | |
| | </table> | | </table> |
| | == Function == | | == Function == |
| - | [[http://www.uniprot.org/uniprot/AP3A_SARS2 AP3A_SARS2]] Forms homotetrameric potassium sensitive ion channels (viroporin) and may modulate virus release. Up-regulates expression of fibrinogen subunits FGA, FGB and FGG in host lung epithelial cells. Induces apoptosis in cell culture. Downregulates the type 1 interferon receptor by inducing serine phosphorylation within the IFN alpha-receptor subunit 1 (IFNAR1) degradation motif and increasing IFNAR1 ubiquitination.[UniProtKB:P59632] | + | [[https://www.uniprot.org/uniprot/AP3A_SARS2 AP3A_SARS2]] Forms homotetrameric potassium sensitive ion channels (viroporin) and may modulate virus release. Up-regulates expression of fibrinogen subunits FGA, FGB and FGG in host lung epithelial cells. Induces apoptosis in cell culture. Downregulates the type 1 interferon receptor by inducing serine phosphorylation within the IFN alpha-receptor subunit 1 (IFNAR1) degradation motif and increasing IFNAR1 ubiquitination.[UniProtKB:P59632] |
| | <div style="background-color:#fffaf0;"> | | <div style="background-color:#fffaf0;"> |
| | == Publication Abstract from PubMed == | | == Publication Abstract from PubMed == |
| - | SARS-CoV-2 encodes three putative ion channels: E, 8a, and 3a. In related SARS-CoV-1, 3a is implicated in viral release, inflammasome activation, and cell death and its deletion reduces viral titer and morbidity in animal models, suggesting 3a-targeted therapeutics could treat SARS and COVID-19. However, the structural basis for the function of 3a is unknown. Here, we show that SARS-CoV-2 forms large conductance cation channels and present cryo-EM structures of dimeric and tetrameric SARS-CoV-2 3a in lipid nanodiscs. 3a adopts a novel fold and is captured in a closed or inactivated state. A narrow bifurcated exterior pore precludes conduction and leads to a large polar cavity open to the cytosol. 3a function is conserved in a common variant among circulating SARS-CoV-2 that alters the channel pore. We identify 3a-like proteins in Alpha- and Beta-coronaviruses that infect bats and humans, suggesting therapeutics targeting 3a could treat a range of coronaviral diseases. | + | SARS-CoV-2 ORF3a is a putative viral ion channel implicated in autophagy inhibition, inflammasome activation and apoptosis. 3a protein and anti-3a antibodies are found in infected patient tissues and plasma. Deletion of 3a in SARS-CoV-1 reduces viral titer and morbidity in mice, suggesting it could be an effective target for vaccines or therapeutics. Here, we present structures of SARS-CoV-2 3a determined by cryo-EM to 2.1-A resolution. 3a adopts a new fold with a polar cavity that opens to the cytosol and membrane through separate water- and lipid-filled openings. Hydrophilic grooves along outer helices could form ion-conduction paths. Using electrophysiology and fluorescent ion imaging of 3a-reconstituted liposomes, we observe Ca(2+)-permeable, nonselective cation channel activity, identify mutations that alter ion permeability and discover polycationic inhibitors of 3a activity. 3a-like proteins are found across coronavirus lineages that infect bats and humans, suggesting that 3a-targeted approaches could treat COVID-19 and other coronavirus diseases. |
| | | | |
| - | Cryo-EM structure of the SARS-CoV-2 3a ion channel in lipid nanodiscs.,Kern DM, Sorum B, Hoel CM, Sridharan S, Remis JP, Toso DB, Brohawn SG bioRxiv. 2020 Jun 18. doi: 10.1101/2020.06.17.156554. PMID:32587976<ref>PMID:32587976</ref> | + | Cryo-EM structure of SARS-CoV-2 ORF3a in lipid nanodiscs.,Kern DM, Sorum B, Mali SS, Hoel CM, Sridharan S, Remis JP, Toso DB, Kotecha A, Bautista DM, Brohawn SG Nat Struct Mol Biol. 2021 Jul;28(7):573-582. doi: 10.1038/s41594-021-00619-0., Epub 2021 Jun 22. PMID:34158638<ref>PMID:34158638</ref> |
| | | | |
| | From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | | From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> |
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| | __TOC__ | | __TOC__ |
| | </StructureSection> | | </StructureSection> |
| - | [[Category: 2019-ncov]] | |
| | [[Category: Large Structures]] | | [[Category: Large Structures]] |
| - | [[Category: Brohawn, S G]] | + | [[Category: Severe acute respiratory syndrome coronavirus 2]] |
| - | [[Category: Hoel, C M]] | + | [[Category: Brohawn SG]] |
| - | [[Category: Kern, D M]] | + | [[Category: Hoel CM]] |
| - | [[Category: Coronavirus]] | + | [[Category: Kern DM]] |
| - | [[Category: Ion channel]]
| + | |
| - | [[Category: Sars-cov-2]]
| + | |
| - | [[Category: Transport protein]]
| + | |
| - | [[Category: Viroporin]]
| + | |
| Structural highlights
Function
[AP3A_SARS2] Forms homotetrameric potassium sensitive ion channels (viroporin) and may modulate virus release. Up-regulates expression of fibrinogen subunits FGA, FGB and FGG in host lung epithelial cells. Induces apoptosis in cell culture. Downregulates the type 1 interferon receptor by inducing serine phosphorylation within the IFN alpha-receptor subunit 1 (IFNAR1) degradation motif and increasing IFNAR1 ubiquitination.[UniProtKB:P59632]
Publication Abstract from PubMed
SARS-CoV-2 ORF3a is a putative viral ion channel implicated in autophagy inhibition, inflammasome activation and apoptosis. 3a protein and anti-3a antibodies are found in infected patient tissues and plasma. Deletion of 3a in SARS-CoV-1 reduces viral titer and morbidity in mice, suggesting it could be an effective target for vaccines or therapeutics. Here, we present structures of SARS-CoV-2 3a determined by cryo-EM to 2.1-A resolution. 3a adopts a new fold with a polar cavity that opens to the cytosol and membrane through separate water- and lipid-filled openings. Hydrophilic grooves along outer helices could form ion-conduction paths. Using electrophysiology and fluorescent ion imaging of 3a-reconstituted liposomes, we observe Ca(2+)-permeable, nonselective cation channel activity, identify mutations that alter ion permeability and discover polycationic inhibitors of 3a activity. 3a-like proteins are found across coronavirus lineages that infect bats and humans, suggesting that 3a-targeted approaches could treat COVID-19 and other coronavirus diseases.
Cryo-EM structure of SARS-CoV-2 ORF3a in lipid nanodiscs.,Kern DM, Sorum B, Mali SS, Hoel CM, Sridharan S, Remis JP, Toso DB, Kotecha A, Bautista DM, Brohawn SG Nat Struct Mol Biol. 2021 Jul;28(7):573-582. doi: 10.1038/s41594-021-00619-0., Epub 2021 Jun 22. PMID:34158638[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Kern DM, Sorum B, Mali SS, Hoel CM, Sridharan S, Remis JP, Toso DB, Kotecha A, Bautista DM, Brohawn SG. Cryo-EM structure of SARS-CoV-2 ORF3a in lipid nanodiscs. Nat Struct Mol Biol. 2021 Jul;28(7):573-582. doi: 10.1038/s41594-021-00619-0., Epub 2021 Jun 22. PMID:34158638 doi:http://dx.doi.org/10.1038/s41594-021-00619-0
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