A comparative study of the Nsp9 RNA binding interface of SARS CoV-2 and MERS coronaviruses

Abstract

Middle East respiratory syndrome coronavirus (MERS CoV) and severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) are RNA viruses from the Betacoronavirus family that cause serious respiratory illness in humans. One of the conserved viral proteins encoded for by the coronavirus family is non-structural protein 9 (nsp9). Nsp9 plays an important role in the RNA capping process of the viral genome, where it is covalently linked to viral RNA (RNAylation) by the conserved viral polymerase, nsp12. Nsp9 also directly binds to RNA; my research group has recently revealed a distinct RNA recognition interface in the SARS CoV-2 nsp9 by using a combination of nuclear magnetic resonance (NMR) spectroscopy and biolayer interferometry (BLI). In this study, I have utilised the same methodology to determine a structural model of RNA binding of the related MERS CoV nsp9. This work has uncovered important similarities and differences to SARS CoV-2 nsp9 and, based on these data, a conserved RNA binding interface for nsp9 proteins of the coronavirus family is proposed. I also show that replacing key RNA binding residues in MERS CoV nsp9 affects RNAylation efficiency, indicating that recognition of RNA may play a role in the capping process of the virus.

Date of Award	2023
Original language	English
Awarding Institution	Western Sydney University
Supervisor	Liza Cubeddu (Supervisor)