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 bacterially-expressed SBV nucleoprotein to 3.06A 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.
Structure of Schmallenberg orthobunyavirus nucleoprotein suggests a novel mechanism for genome encapsidation.,Dong H, Li P, Elliott RM, Dong C J Virol. 2013 Mar 6. PMID:23468499
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↑ Dong H, Li P, Elliott RM, Dong C. Structure of Schmallenberg orthobunyavirus nucleoprotein suggests a novel mechanism for genome encapsidation. J Virol. 2013 Mar 6. PMID:23468499 doi:10.1128/JVI.00223-13