SARS-Coronavirus-2 Nsp13 Possesses NTPase and RNA Helicase Activities That Can Be Inhibited by Bismuth Salts

Abstract

The ongoing outbreak of Coronavirus Disease 2019 has become a global public health emergency. SARScoronavirus-2 (SARS-CoV-2), the causative pathogen of COVID-19, is a positive-sense single-stranded RNA virus belonging to the family Coronaviridae. For RNA viruses, virus-encoded RNA helicases have long been recognized to play pivotal roles during viral life cycles by facilitating the correct folding and replication of viral RNAs. Here, our studies show that SARS-CoV-2-encoded nonstructural protein 13 (nsp13) possesses the nucleoside triphosphate hydrolase (NTPase) and RNA helicase activities that can hydrolyze all types of NTPs and unwind RNA helices dependently of the presence of NTP, and further characterize the biochemical characteristics of these two enzymatic activities associated with SARS-CoV-2 nsp13. Moreover, we found that some bismuth salts could effectively inhibit both the NTPase and RNA helicase activities of SARS-CoV-2 nsp13 in a dose-dependent manner. Thus, our findings demonstrate the NTPase and helicase activities of SARS-CoV-2 nsp13, which may play an important role in SARS-CoV-2 replication and serve as a target for antivirals.

Computational identification of human biological processes and protein sequence motifs putatively targeted by SARS-CoV-2 proteins using protein-protein interaction networks

“…It has been an early pharmaceutical target for SARS-CoV inhibition, with intention to reduce the unwinding ability of the viral helicase 28 . It was proven to be a promising molecular target for as the viral helicase could be inhibited without affecting the activity of the human helicase 29 , and this protein continues to be studied for the novel SARS-CoV-2 30,31 . However, the exact interactions between Nsp13 and MTOC have not been characterized to our knowledge.…”

The Novel Insight of SARS-CoV-2 Molecular Biology and Pathogenesis and Therapeutic Options

“…A research report has shown that bismuth salts such as potassium citrate (BPC), ranitidine bismuth citrate (RBC), and bismuth citrate would inhibit NTPase and RNA helix-unwinding behaviors of SARS-CoV-2 nsp13. Among them, BPC or RBC can significantly impair SARS-CoV-2 nsp13-dependent NTPase and RNA helicase activities (Shu et al, 2020).…”

Structural analysis of SARS-CoV-2 genome and predictions of the human interactome

“…DDX1 has been shown to enable the switch from discontinuous to continuous transcription in SARS-CoV-1 infection and its knockdown reduced the number of longer sub-genomic mRNA (sgmRNA) through interaction with the SARS-CoV-1 nucleocapsid protein N 60 and Nsp14 61 . It functions as a bidirectional helicase, which distinguishes it from the coronaviruses helicases, which can only unwind RNA in the 5' to 3' direction 62 , a very important function in highly structured RNA such SARS-CoV-2. DDX1 is also required for HIV-1 Rev as well as for avian coronavirus IBV replication and it binds to the RRE sequence of HIV-1 RNAs 1-3 , while CCNT1 binds to 7SK snRNA and regulates transactivation domain of the viral nuclear transcriptional activator, Tat 65,66 .…”