Phosphorylation of the varicella-zoster virus (VZV) major transcriptional regulatory protein IE62 by the VZV open reading frame 66 protein kinase.

IE62, the major transcriptional regulatory protein encoded by varicella-zoster virus (VZV), is nuclear at early times of VZV infection but then becomes predominantly cytoplasmic as a result of expression of the protein kinase encoded by open reading frame 66 (ORF66). Cytoplasmic forms of IE62 are required for its inclusion as an abundant VZV virion tegument protein. Here we show that ORF66 directly phosphorylates IE62 at two residues, with phosphorylation at S686 being sufficient to regulate IE62 nuclear import.

Virion association of IE62, the varicella-zoster virus (VZV) major transcriptional regulatory protein, requires expression of the VZV open reading frame 66 protein kinase.

IE62, the major transcriptional regulatory protein encoded by varicella-zoster virus (VZV), is associated with the tegument of gradient-purified virions. Here, we show that most, if not all, of the association requires the expression of open reading frame 66 (ORF66), a protein kinase. The association of IE62 with wild-type VZV virions was confirmed using immunoelectron microscopy with IE62-specific antibodies, which reacted with virions in ultrathin sections of VZV-infected cells.

Nuclear accumulation of IE62, the varicella-zoster virus (VZV) major transcriptional regulatory protein, is inhibited by phosphorylation mediated by the VZV open reading frame 66 protein kinase.

IE62, the major transcriptional activator protein encoded by varicella-zoster virus (VZV), locates to the nucleus when expressed in transfected cells. We show here that cytoplasmic forms of IE62 accumulate in transfected and VZV-infected cells as the result of the protein kinase activity associated with VZV open reading frame 66 (ORF66). Expression of the ORF66 protein kinase but not the VZV ORF47 protein kinase impaired the ability of coexpressed IE62 to transactivate promoter-reporter constructs.

Regulated nuclear localization of the varicella-zoster virus major regulatory protein, IE62.

The major transcriptional regulatory protein encoded by varicella-zoster virus (VZV), IE62, accumulates within the nucleus of transfected and VZV-infected cells. Data are presented to show that nuclear localization of IE62 is dependent upon charged amino acids mapping to residues 677-685 of the 1310 residue protein. Furthermore, coexpression of VZV open-reading frame (ORF) 66 with IE62 results in the accumulation of cytoplasmic forms of IE62, suggesting that the ORF 66 protein can override the IE62 nuclear localization signal.

Transcriptional mapping of varicella-zoster virus regulatory proteins.

Varicella-zoster virus (VZV) expresses four proteins that influence viral transcriptional events and that also are homologous to herpes simplex virus type 1 (HSV-1) immediate-early proteins. However, their transcription and the mechanisms by which it is regulated are not yet resolved. To identify the promoter regions, a precise knowledge of the initiation and termination of the encoded RNAs is first required.