Structural insights into RNA encapsidation and helical assembly of the Toscana virus nucleoprotein
Authors
- D. Olal
- A. Dick
- V.L. Woods
- T. Liu
- S. Li
- S. Devignot
- F. Weber
- E.O. Saphire
- O. Daumke
Journal
- Nucleic Acids Research
Citation
- Nucleic Acids Res 42 (9): 6025-6037
Abstract
Toscana virus is an emerging bunyavirus in Mediterranean Europe where it accounts for 80% of pediatric meningitis cases during the summer. The negative-strand ribonucleic acid (RNA) genome of the virus is wrapped around the virally encoded nucleoprotein N to form the ribonucleoprotein complex (RNP). We determined crystal structures of hexameric N alone (apo) and in complex with a nonameric single-stranded RNA. RNA is sequestered in a sequence-independent fashion in a deep groove inside the hexamer. At the junction between two adjacent copies of Ns, RNA binding induced an inter-subunit rotation, which opened the RNA-binding tunnel and created a new assembly interface at the outside of the hexamer. Based on these findings, we suggest a structural model for how binding of RNA to N promotes the formation of helical RNPs, which are a characteristic hallmark of many negative-strand RNA viruses.