DEXSM-box helicase domain of coronavirus Nsp13 helicase
Helicases catalyze the NTP-dependent unwinding of nucleic acid duplexes into single strands and are classified into six superfamilies based on the arrangement of conserved motifs. This family contains coronavirus (CoV) non-structural protein 13 (Nsp13) helicase, including those from highly pathogenic human betaCoVs such as Severe Acute Respiratory Syndrome coronavirus (SARS) and SARS-CoV-2 (also known as 2019 novel CoV (2019-nCoV) or COVID-19 virus). Nsp13 helicase is a component of the viral RNA synthesis replication and transcription complex (RTC). SARS-Nsp13 is strongly inhibited by natural flavonoids, myricetin and scutellarein, and is emerging as a target for development of anti-SARS medications. It contains an N-terminal Cys/His rich zinc-binding domain (CH/ZBD), a stalk domain, a 1B regulatory domain, and an SF1 helicase core that carries a DEAD-box helicase domain. Nsp13 belongs to the DEAD-like helicase superfamily, a diverse family of proteins involved in ATP-dependent RNA or DNA unwinding. This domain contains the ATP-binding region.
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