betacoronavirus non-structural protein 2 (Nsp2) similar to bat coronavirus HKU9 Nsp2, and related proteins from betacoronaviruses in the D lineage
Coronavirus non-structural proteins (Nsps) are encoded in ORF1a and ORF1b. Post infection, the genomic RNA is released into the cytoplasm of the cell and translated into two long polyproteins (pp), pp1a and pp1ab, which are then autoproteolytically cleaved by two viral proteases Nsp3 and Nsp5 into smaller subunits. Nsp2 is one of these subunits. This subgroup includes Nsp2 from Rousettus bat coronavirus HKU9 and betacoronaviruses in the nobecovirus subgenus (D lineage). It belongs to a family which includes Severe acute respiratory syndrome coronavirus (SARS-CoV) Nsp2, and Murine hepatitis virus (MHV) Nsp2 (also known as p65). The function of Nsp2 remains unclear. SARS-CoV Nsp2, rather than playing a role in viral replication, may be involved in altering the host cell environment; deletion of Nsp2 from the SARS-CoV genome results in only a modest reduction in viral titers. It has been shown to interact with two host proteins, prohibitin 1 (PHB1) and PHB2, which have been implicated in cellular functions, including cell-cycle progression, cell migration, cellular differentiation, apoptosis, and mitochondrial biogenesis. MHV Nsp2/p65, different from SARS-CoV Nsp2, may play an important role in the viral life cycle.
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