8.B.42. The Coronavirus Orf6 (CV-Orf6) Family (formally TC# 9.B.380)
Proteins of this family are small (30 - 60 aas) and have a single TMS. They are exclusively from coronaviruses. Orf6 disrupts bidirectional nucleocytoplasmic transport by interacting with the host RAE1-NUP98 complex (Kato et al. 2021, Addetia et al. 2021). It also disrupts cell nuclear import complex formation by tethering karyopherin alpha 2 and karyopherin beta 1 to the membrane (Xia et al. 2020). Retention of import factors at the ER/Golgi membrane leads to a loss of transport into the nucleus. It prevents STAT1 nuclear translocation in response to interferon signaling, thus blocking the expression of interferon stimulated genes that display multiple antiviral activities (Miorin et al. 2020). It suppresses IFN-beta production, possibly by blocking IRF3 nuclear translocation (Xia et al. 2020). SARS-CoV-2 ORF6 localization and interferon antagonism can be decoupled (Wong et al. 2022).