Crystal structure of tomato spotted wilt virus GN reveals a dimer complex formation and evolutionary link to animal-infecting viruses

Tospoviridae is a family of enveloped RNA plant viruses that infect many field crops, inflicting a heavy global economic burden. These tripartite, single-stranded, negative-sense RNA viruses are transmitted from plant to plant by thrips as the insect vector. The medium (M) segment of the viral genome encodes two envelope glycoproteins, G_Nand G_C, which together form the envelope spikes. G_Cis considered the virus fusogen, while the accompanying G_Nprotein serves as an attachment protein that binds to a yet unknown receptor, mediating the virus acquisition by the thrips carrier. Here we present the crystal structure of glycoprotein N (G_N) from the tomato spotted wilt virus (TSWV), a representative member of the Tospoviridae family. The structure suggests that G_Nis organized as dimers on TSWV's outer shell. Our structural data also suggest that this dimerization is required for maintaining G_Nstructural integrity. Although the structure of the TSWV G_Nis different from other bunyavirus G_Nproteins, they all share similar domain connectivity that resembles glycoproteins from unrelated animal-infecting viruses, suggesting a common ancestor for these accompanying proteins.