Abstract
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(N) and G(C), which together form the envelope spikes. G(C) is considered the virus fusogen, while the accompanying G(N) protein 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(N) is organized as dimers on TSWV's outer shell. Our structural data also suggest that this dimerization is required for maintaining G(N) structural integrity. Although the structure of the TSWV G(N) is different from other bunyavirus G(N) proteins, they all share similar domain connectivity that resembles glycoproteins from unrelated animal-infecting viruses, suggesting a common ancestor for these accompanying proteins.