SARS-CoV-2 non-structural protein 12 Nidovirus-dependent RNA capping domain (nsp12 NiRAN domain)

The SARS-CoV-2 nucleotidyltransferase domain, specifically known as the Nidovirus-dependent RNA capping (NiRAN) domain, is an essential enzymatic region located at the N-terminus of the non-structural protein 12 (nsp12). This domain is a defining feature of the Nidovirales order and plays a pivotal role in the viral replication-transcription complex by facilitating an unconventional RNA capping pathway. It functions by transferring a nucleoside monophosphate to the N-terminus of the viral protein nsp9, a process known as nucleotidylation, which is a prerequisite for viral mRNA capping and stability. Because the NiRAN domain is highly conserved across SARS-CoV-2 variants and lacks a direct human homolog, it represents an ideal target for the development of broad-spectrum antiviral therapies. Inhibiting this domain, for instance with the drug suramin, effectively blocks the production of functional viral mRNA and prevents the virus from evading the host's innate immune system. Consequently, the NiRAN domain is a focus of intense research for therapeutic intervention to complement existing polymerase inhibitors.

Other names

NiRAN domainnsp12 N-terminal domainNidovirus-dependent RNA capping domainSARS-CoV-2 nsp12 nucleotidyltransferase

Inhibition of the nucleotidyltransferase activity of the NiRAN domain, preventing the nucleotidylation of nsp9 and subsequent RNA capping, which disrupts viral replication and immune evasion.