4IDX

Structure of Schmallenberg orthobunyavirus nucleoprotein suggests a novel mechanism of genome encapsidation

(2013) J Virol 87: 5593-5601

• PubMed: 23468499 Search on PubMedSearch on PubMed Central
• DOI: https://doi.org/10.1128/JVI.00223-13
• Primary Citation of Related Structures:  
  4IDU, 4IDX


• PubMed Abstract: 
  

  Schmallenberg virus (SBV), a newly emerged orthobunyavirus (family Bunyaviridae), has spread rapidly across Europe and has caused congenital abnormalities in the offspring of cattle, sheep, and goats. Like other orthobunyaviruses, SBV contains a tripartite negative-sense RNA genome that encodes four structural and two nonstructural proteins. The nucleoprotein (N) encapsidates the three viral genomic RNA segments and plays a crucial role in viral RNA transcription and replication. Here we report the crystal structure of the bacterially expressed SBV nucleoprotein to a 3.06-Å resolution. The protomer is composed of two domains (N-terminal and C-terminal domains) with flexible N-terminal and C-terminal arms. The N protein has a novel fold and forms a central positively charged cleft for genomic RNA binding. The nucleoprotein purified under native conditions forms a tetramer, while the nucleoprotein obtained following denaturation and refolding forms a hexamer. Our structural and functional analyses demonstrate that both N-terminal and C-terminal arms are involved in N-N interaction and oligomerization and play an essential role in viral RNA synthesis, suggesting a novel mechanism for viral RNA encapsidation and transcription.

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Organizational Affiliation: 

Biomedical Research Centre, Norwich Medical School, University of East Anglia, Norwich Research Park, Norwich, United Kingdom.