COVID-19 Nsp13 Helicase Analysis: Assessment of Unwinding SARS-CoV-2 Mutagenic RNA Secondary Structures and Pharmacological Modulation in a Preclinical Model

National Institute On Aging

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Abstract

Point mutations in the SARS-CoV-2 genome have potential consequences for the novel coronavirus life cycle, leading to alterations in its ability to replicate or transcribe its genome with an impact on transmission and virulence. Therefore, characterization of the cis- and trans-activating factors responsible for genetic variation will lead to a better understanding of the novel coronavirus virulency. Mapping point mutations in secondary RNA structures of the SARS-CoV-2 genome will be performed to determine their enrichment and delineate if coronavirus nucleic acid structure plays a role in mutagenesis. Among the key players in SARS-CoV-2 replication predicted to act upon RNA secondary structures formed by G4 and SL sequence motifs in the coronavirus genome is the virally encoded RNA helicase Nsp13. Nsp13, in complex with the Nsp12 RNA-dependent RNA polymerase, processivity factors (Nsp7, Nsp8), and proofreading exonuclease (Nsp14) potentially coordinate with host cell factors in a still not well understood mechanism to replicate the coronavirus RNA genome. Characterizing the molecular functions of Nsp13 is important to understand its role in the mechanism of coronavirus genome duplication and transcription. Nsp13, like other proteins implicated in coronavirus genome replication, may be a useful target for pharmacological modulation as an anti-viral strategy to combat the virus and potentially treat symptoms of COVID-19 in infected individuals. The proposed studies will employ a SARS-CoV-2 Nsp13 helicase targeted library to assess replication of the mouse hepatitis virus (MHV), an excellent model for SARS-CoV-2.