Tomato spotted wilt virus GC and N proteins interact in vivo

Abstract Tomato spotted wilt virus (TSWV) virions consist of a nucleocapsid core surrounded by a membrane containing glycoproteins G n and G c . To unravel the protein interactions involved in the membrane acquisition of RNPs, TSWV nucleocapsid protein (N), G n and G c were expressed and analyzed in BHK21 cells. Upon coexpression of G n , G c and N, a partial colocalization of N with both glycoproteins was observed in the Golgi region. In contrast, upon coexpression of G c and N in the absence of G n , both proteins colocalized to a distinct non-Golgi perinuclear region. Using FLIM and FRET, interaction was demonstrated between N and G c , but not between N and G n , and was only observed in the region where both proteins accumulated. The genuine character of N–G c interaction was confirmed by its presence in purified virus and RNP preparations. The results are discussed in view of TSWV particle assembly taking place at the Golgi complex.