Non-structural protein ORF5 from Middle East respiratory syndrome-related coronavirus and related betacoronaviruses in the C lineage
This model represents the non-structural protein ORF5 from Middle East respiratory syndrome-related coronavirus (MERS-CoV) and and similar proteins from betacoronaviruses in the merbecovirus subgenera (C lineage). ORF5 is also called non-structural protein 3d (NS3d) or accessory protein 3d in some bat merbecoviruses. There are five essential genes in CoVs that result in the following gene products: Spike (S) protein, Membrane (M) glycoprotein, Nucleocapsid (N), Envelope (E) protein, and replicase/protease polyproteins (ORF1ab); all are required to produce a structurally complete viral particle. In addition, CoV genomes also contain ORFs coding for accessory proteins that are specific for certain CoV lineages or for a particular CoV. In general, CoV accessory proteins are considered to be dispensable for viral replication; however, several accessory proteins have been shown to exhibit functions in virus-host interactions during CoV infection. MERS-CoV is a highly pathogenic respiratory virus with pathogenic mechanisms that may be driven by innate immune pathways. MERS-CoV ORF5 acts as an interferon antagonist and may play a role in circumventing the innate immunity of host cells. It is also implicated to play a role in the modulation of NF-kappaB-mediated inflammation. ORF5/NS3d from merbecovirus (betacoronavirus, lineage C) may not be related to ORF5 proteins from other lineages.
Jiyao W et al.(2023). "The conserved domain database in 2023.",