Characterization of the varicella-zoster virus gene 61 protein

The protein predicted to be encoded by varicella-zoster virus (VZV) gene 61 exhibits limited amino acid sequence similarity to the herpes simplex virus type 1 nuclear phosphoprotein Vmw110, which functions as a transcriptional activator. The gene 61 protein was expressed in its entirety, or as an amino- or carboxy-terminal fragment in Escherichia coli and vaccinia virus recombinants, and monospecific rabbit antisera were raised against an E. coli fusion between beta-galactosidase and the majority of the gene 61 protein. Use of the antisera showed that the gene 61 protein is present in VZV-infected cell nuclei as a heterogeneous phospho-protein of Mr62K to 65K. Phosphorylation occurs in the amino- and, to a lesser extent, carboxy-terminal portions of the protein. The carboxy-terminal region directs transport of the protein to the nucleus, whereas the amino-terminal region, which contains a potential zinc-binding domain, is responsible for a punctate distribution. Preliminary mapping data indicated that gene 61 is transcribed as a 1.8 kb mRNA which initiates about 65 bp upstream from the translation initiation codon, at a position located appropriately with respect to potential regulatory elements.