Coronavirus N protein N-terminal domain (NTD) specifically binds the transcriptional regulatory sequence (TRS) and melts TRS-cTRS RNA duplexes. Academic Article uri icon

abstract

  • All coronaviruses (CoVs), including the causative agent of severe acute respiratory syndrome (SARS), encode a nucleocapsid (N) protein that harbors two independent RNA binding domains of known structure, but poorly characterized RNA binding properties. We show here that the N-terminal domain (NTD) of N protein from mouse hepatitis virus (MHV), a virus most closely related to SARS-CoV, employs aromatic amino acid-nucleobase stacking interactions with a triple adenosine motif to mediate high-affinity binding to single-stranded RNAs containing the transcriptional regulatory sequence (TRS) or its complement (cTRS). Stoichiometric NTD fully unwinds a TRS-cTRS duplex that mimics a transiently formed transcription intermediate in viral subgenomic RNA synthesis. Mutation of the solvent-exposed Y127, positioned on the beta-platform surface of our 1.75 A structure, binds the TRS far less tightly and is severely crippled in its RNA unwinding activity. In contrast, the C-terminal domain (CTD) exhibits no RNA unwinding activity. Viruses harboring Y127A N mutation are strongly selected against and Y127A N does not support an accessory function in MHV replication. We propose that the helix melting activity of the coronavirus N protein NTD plays a critical accessory role in subgenomic RNA synthesis and other processes requiring RNA remodeling.

published proceedings

  • J Mol Biol

altmetric score

  • 0.25

author list (cited authors)

  • Grossoehme, N. E., Li, L., Keane, S. C., Liu, P., Dann, C. E., Leibowitz, J. L., & Giedroc, D. P.

citation count

  • 99

complete list of authors

  • Grossoehme, Nicholas E||Li, Lichun||Keane, Sarah C||Liu, Pinghua||Dann, Charles E||Leibowitz, Julian L||Giedroc, David P

publication date

  • December 2009