KSPublications - Ribonucleocapsid formation of SARS-CoV through...

Title

Ribonucleocapsid formation of SARS-CoV through molecular action of the N-terminal domain of N protein.

Authors

Saikatendu KS, et al.

Abstract

Conserved amongst all coronaviruses are four structural proteins, the matrix (M), small envelope (E) and spike (S) that are embedded in the viral membrane and the nucleocapsid phosphoprotein (N), which exists in a ribonucleoprotein complex in their lumen. The N terminal domain of coronaviral N proteins (N-NTD) provides a scaffold for RNA binding while the C-terminal domain (N-CTD) mainly acts as oligomerization modules during assembly. The C-terminus of N protein anchors it to the viral membrane by associating with M protein. We characterized the structures of N-NTD from severe acute respiratory syndrome coronavirus (SARS-CoV) in two crystal forms, at 1.17A (monoclinic) and 1.85 A (cubic) respectively, solved by molecular replacement using the homologous avian infectious bronchitis virus (IBV) structure. Flexible loops in the solution structure of SARS-CoV N-NTD are now shown to be well ordered around the beta-sheet core. The functionally important positively charged beta-hairpin protrudes out of the core and is oriented similar to that in the IBV N-NTD and is involved in crystal packing in the monoclinic form. In the cubic form, the monomers form trimeric units that stack in a helical array. Comparison of crystal packing of SARS-CoV and IBV N-NTDs suggest a common mode of RNA recognition, but probably associate differently in vivo during the formation of the ribonucleoprotein complex. Electrostatic potential distribution on the surface of homology models of related coronaviral N-NTDs hints that they employ different modes of both RNA recognition as well as oligomeric assembly, perhaps explaining why their nucleocapsids have different morphologies.

Journal

Journal of Virology

Date

1/17/2007

Link

PubMed Entry

Reference

Saikatendu KS, Joseph JS, Subramanian V, Neuman BW, Buchmeier MJ, Stevens RC, Kuhn P. -"Ribonucleocapsid formation of SARS-CoV through molecular action of the N-terminal domain of N protein." J Virol. 2007 Jan 17; [Epub ahead of print]

PMID

17229691

Keyword

FSPS

TSRI Number

18527

Attachments

Kuhn Lab at The Scripps Research Institute.