The cytoplasmic tail of Herpes simplex virus glycoprotein H binds to the tegument protein VP16 in vitro and in vivo

During Herpes simplex virus envelopment, capsids, tegument polypeptides, and membrane proteins assemble at the site of budding and a cellular lipid bilayer becomes refashioned into a spherical envelope. Though the molecular interactions driving these events are poorly understood, several lines of evidence suggest that associations between envelope protein cytoplasmic tails and tegument polypeptides may play important roles. Consistent with this hypothesis, we show here that a fusion of the cytoplasmic tail of gH with Glutathione-S-Transferase binds to VP16 in a temperature-dependent manner. VP16 prepared by in vitro translation behaves in a similar fashion, demonstrating that the interaction is not dependent on other viral polypeptides. Mutational analysis of the gH tail has also enabled us to identify amino acid residues critical for VP16 binding in vitro. A fusion protein in which the gH tail is fused to the carboxy-terminus of GFP coimmunoprecipitates with VP16 in infected cells, indicating that VP16 can interact with the gH tail in vivo.