N-terminal domain of deltacoronavirus Nonstructural protein 15 (Nsp15), and related proteins
Coronavirus (CoV) Nsp15 is a nidovirus endoribonuclease (NendoU). NendoUs are uridylate-specific endoribonucleases, which release a cleavage product containing a 2',3'-cyclic phosphate at the 3' terminal end. NendoUs include coronavirus Nsp15 and arterivirus Nsp11, both of which may participate in the viral replication process and in the evasion of the host immune system. This small NTD structure, present in CoV Nsp15, is missing in Nsp11. CoV Nsp15 has an N-terminal domain, a middle (M) domain, and a C-terminal catalytic (NendoU) domain. Oligomerization of Porcine DeltaCoronavirus (PDCoV) Nsp15 differs from the Nsp15 of alpha- and beta-coronavirus, such as Severe Acute Respiratory Syndrome (SARS)-CoV and Murine Hepatitis Virus (MHV) which form functional hexamers; PDCoV Nsp15 has been shown to exist as dimers and monomers in solution, and to function as a dimer.
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