Nucleocapsid Structure of Negative Strand RNA Virus.

Ming Luo,Shelby Ashlyn Mcmanus,James Ross Terrell

doi:10.3390/v12080835

Abstract

Negative strand RNA viruses (NSVs) include many important human pathogens, such as influenza virus, Ebola virus, and rabies virus. One of the unique characteristics that NSVs share is the assembly of the nucleocapsid and its role in viral RNA synthesis. In NSVs, the single strand RNA genome is encapsidated in the linear nucleocapsid throughout the viral replication cycle. Subunits of the nucleocapsid protein are parallelly aligned along the RNA genome that is sandwiched between two domains composed of conserved helix motifs. The viral RNA-dependent-RNA polymerase (vRdRp) must recognize the protein–RNA complex of the nucleocapsid and unveil the protected genomic RNA in order to initiate viral RNA synthesis. In addition, vRdRp must continuously translocate along the protein–RNA complex during elongation in viral RNA synthesis. This unique mechanism of viral RNA synthesis suggests that the nucleocapsid may play a regulatory role during NSV replication.

Highlights

IntroductionThe capsid consists of viral proteins and encloses the nucleotide genome of the virus
The stuttering function was restored when the U track was extended by an additional U in rescued Vesicular stomatitis virus (VSV) [61]. These results firmly demonstrate that the nucleocapsid protein is an indispensable component in viral RNA synthesis of negative strand RNA viruses (NSVs)
Analogous to the spherical viruses that follow the icosahedral symmetry to assemble the virion, the nucleocapsid of NSV is assembled by linear alignment of the N protein subunits associated through side-by-side and cross-molecule interactions

Summary

Introduction

The capsid consists of viral proteins and encloses the nucleotide genome of the virus. The viral nucleocapsid is assembled by organization of capsid protein subunits following a geometric symmetry, including the icosahedral symmetry for spherical viruses and the helical symmetry for filamentous viruses (read Chapter 3 in Fields Virology for details) [1]. For negative strand RNA viruses (NSVs), the nucleocapsid has a unique structure that is pertinent to its functions in the virus replication cycle. Since 2003, the structure of the nucleocapsid or the capsid protein has been determined for at least 21 genera in Negarnaviricota (Table 1). Common folds of the NSV capsid proteins and principles of nucleocapsid assembly have emerged, and the functional role of the nucleocapsid in the unique NSV viral RNA synthesis has become clearer. It is because of this role that additional examination of the structure of NSV nucleocapsids has become essential for further understanding of NSV replication and pathogenesis

The Capsid Protein Fold

Assembly of the Nucleocapsid

They 2

Viral RNA Synthesis

Conclusions