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

Abstract

Tospoviridaeis 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, GNand GC, which together form the envelope spikes. GCis considered the virus fusogen, while the accompanying GNprotein 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 (GN) from the tomato spotted wilt virus (TSWV), a representative member of theTospoviridaefamily. The structure suggests that GNis organized as dimers on TSWV’s outer shell. Our structural data also suggest that this dimerization is required for maintaining GNstructural integrity. Although the structure of the TSWV GNis different from other bunyavirus GNproteins, they all share similar domain connectivity that resembles glycoproteins from unrelated animal-infecting viruses, suggesting a common ancestor for these accompanying proteins.