8eqs Citations

The SARS-CoV-2 accessory protein Orf3a is not an ion channel, but does interact with trafficking proteins.

Abstract

The severe acute respiratory syndrome associated coronavirus 2 (SARS-CoV-2) and SARS-CoV-1 accessory protein Orf3a colocalizes with markers of the plasma membrane, endocytic pathway, and Golgi apparatus. Some reports have led to annotation of both Orf3a proteins as viroporins. Here we show that neither SARS-CoV-2 nor SARS-CoV-1 Orf3a form functional ion conducting pores and that the conductances measured are common contaminants in overexpression and with high levels of protein in reconstitution studies. Cryo-EM structures of both SARS-CoV-2 and SARS-CoV-1 Orf3a display a narrow constriction and the presence of a positively-charged aqueous vestibule, which would not favor cation permeation. We observe enrichment of the late endosomal marker Rab7 upon SARS-CoV-2 Orf3a overexpression, and co-immunoprecipitation with VPS39. Interestingly, SARS-CoV-1 Orf3a does not cause the same cellular phenotype as SARS-CoV-2 Orf3a and does not interact with VPS39. To explain this difference, we find that a divergent, unstructured loop of SARS-CoV-2 Orf3a facilitates its binding with VPS39, a HOPS complex tethering protein involved in late endosome and autophagosome fusion with lysosomes. We suggest that the added loop enhances SARS-CoV-2 Orf3a's ability to co-opt host cellular trafficking mechanisms for viral exit or host immune evasion.

Articles - 8eqs mentioned but not cited (1)

  1. SARS-CoV-2 ORF3a-Mediated NF-κB Activation Is Not Dependent on TRAF-Binding Sequence. Busscher BM, Befekadu HB, Liu Z, Xiao TS. Viruses 15 2229 (2023)


Reviews citing this publication (2)

  1. To Be or Not to Be an Ion Channel: Cryo-EM Structures Have a Say. Chen GL, Li J, Zhang J, Zeng B. Cells 12 1870 (2023)
  2. SARS-CoV-2 ORF3a Protein as a Therapeutic Target against COVID-19 and Long-Term Post-Infection Effects. Zhang J, Hom K, Zhang C, Nasr M, Gerzanich V, Zhang Y, Tang Q, Xue F, Simard JM, Zhao RY. Pathogens 13 75 (2024)

Articles citing this publication (10)

  1. The SARS-CoV-2 accessory protein Orf3a is not an ion channel, but does interact with trafficking proteins. Miller AN, Houlihan PR, Matamala E, Cabezas-Bratesco D, Lee GY, Cristofori-Armstrong B, Dilan TL, Sanchez-Martinez S, Matthies D, Yan R, Yu Z, Ren D, Brauchi SE, Clapham DE. Elife 12 e84477 (2023)
  2. Tetherin antagonism by SARS-CoV-2 ORF3a and spike protein enhances virus release. Stewart H, Palmulli R, Johansen KH, McGovern N, Shehata OM, Carnell GW, Jackson HK, Lee JS, Brown JC, Burgoyne T, Heeney JL, Okkenhaug K, Firth AE, Peden AA, Edgar JR. EMBO Rep 24 e57224 (2023)
  3. Porcine deltacoronavirus accessory protein NS6 harnesses VPS35-mediated retrograde trafficking to facilitate efficient viral infection. Fang P, Zhang H, Cheng T, Ding T, Xia S, Xiao W, Li Z, Xiao S, Fang L. J Virol 97 e0095723 (2023)
  4. SARS-CoV-2 E and 3a Proteins Are Inducers of Pannexin Currents. Oliveira-Mendes BBR, Alameh M, Ollivier B, Montnach J, Bidère N, Souazé F, Escriou N, Charpentier F, Baró I, De Waard M, Loussouarn G. Cells 12 1474 (2023)
  5. Some aspects of the life of SARS-CoV-2 ORF3a protein in mammalian cells. Jiao S, Miranda P, Li Y, Maric D, Holmgren M. Heliyon 9 e18754 (2023)
  6. ER-export and ARFRP1/AP-1-dependent delivery of SARS-CoV-2 Envelope to lysosomes controls late stages of viral replication. Pearson GJ, Mears HV, Broncel M, Snijders AP, Bauer DLV, Carlton JG. Sci Adv 10 eadl5012 (2024)
  7. Exploring polyamine interactions and binding pockets in SARS-CoV-2 ORF3a. Boonamnaj P, Pandey RB, Sompornpisut P. J Mol Graph Model 122 108487 (2023)
  8. SARS-CoV-2 virulence factor ORF3a blocks lysosome function by modulating TBC1D5-dependent Rab7 GTPase cycle. Walia K, Sharma A, Paul S, Chouhan P, Kumar G, Ringe R, Sharma M, Tuli A. Nat Commun 15 2053 (2024)
  9. Targeting the High-Density Lipoprotein Proteome for the Treatment of Post-Acute Sequelae of SARS-CoV-2. Grote K, Schaefer AC, Soufi M, Ruppert V, Linne U, Mukund Bhagwat A, Szymanski W, Graumann J, Gercke Y, Aldudak S, Hilfiker-Kleiner D, Schieffer E, Schieffer B. Int J Mol Sci 25 4522 (2024)
  10. The SARS coronavirus accessory protein ORF3a rescues potassium conductance in yeast. Rosenbaum JC, Carlson AE. MicroPubl Biol 2024 (2024)


Related citations provided by authors (1)

  1. The SARS-CoV-2 accessory protein Orf3a is not an ion channel, but does interact with trafficking proteins.. Miller AN, Houlihan PR, Matamala E, Cabezas-Bratesco D, Lee GY, Cristofori-Armstrong B, Dilan TL, Sanchez-Martinez S, Matthies D, Yan R, Yu Z, Ren D, Brauchi SE, Clapham DE bioRxiv (2022)