Non-structural protein 13 (NSP13) helicase (NSP13)

The SARS-CoV-2 non-structural protein 13 (NSP13) is a highly conserved helicase essential for viral replication and transcription. It belongs to the Superfamily 1B (SF1B) and functions by unwinding double-stranded RNA or DNA in a 5'-to-3' direction, fueled by the hydrolysis of ATP (UniProt: P0DTD1). The protein consists of five domains: a zinc-binding domain (ZBD), a stalk domain, a 1B domain, and two RecA-like helicase subdomains (1A and 2A) that form the catalytic core. The nucleic-acid binding site is located in a deep cleft between the 1A and 2A domains, where it accommodates the single-stranded template during the unwinding process (PubMed: 32780104). Because NSP13 is among the most conserved proteins across the Coronaviridae family, it is a primary target for broad-spectrum antiviral drug development. Inhibitors targeting the nucleic-acid binding site aim to physically block the entry or translocation of the RNA substrate, effectively halting the viral replication complex (PubMed: 33167431). Additionally, the site is adjacent to the ATP-binding pocket, allowing for potential dual-mechanism inhibition (PubMed: 34385553). Targeting this specific site is advantageous as it may reduce the likelihood of viral escape compared to targets with higher mutation rates.

Other names

SARS-CoV-2 helicaseNon-structural protein 13RNA helicaseReplicase polyprotein 1ab helicaseNSP13_SARS2

Inhibition of the helicase activity by blocking the nucleic acid binding site or the ATP-binding pocket, thereby preventing the unwinding of double-stranded RNA templates required for viral replication.