Phosphorylation of the Epstein-Barr virus BZLF1 immediate-early gene product ZEBRA.
Expression of the Epstein-Barr virus (EBV) BZLF1 gene product ZEBRA is a first step in the cascade of the virus-productive cycle. ZEBRA protein was detected by immunoblotting as a single band at 38 kDa in Akata cells after crosslinkage of membrane immunoglobulin G (IgG) with anti-IgG antibody. Immunoprecipitation of [32P]phosphate-labeled, anti-IgG-stimulated Akata cells with anti-ZEBRA antibody showed that ZEBRA was phosphorylated. Phosphoamino acid analysis demonstrated phosphorylation of serine, but not threonine or tyrosine, and tryptic-peptide mapping showed multiple phosphorylated peptides of ZEBRA. Treatment with 8-bromo cAMP and blockage of phosphodiesterase by theophylline in anti-IgG-stimulated cells increased the phosphorylation of three ZEBRA peptides. Incubation with 12-O-tetradecanoylphorbol-13-acetate (TPA) reduced the phosphorylation of these three ZEBRA peptides, while treatment with staurosporine, a protein kinase C (PKC) inhibitor, enhanced their phosphorylations. These data suggest that activation of PKC with TPA induces the ZEBRA dephosphorylation and that activation of cAMP-dependent protein kinase A enhances the ZEBRA phosphorylation at the specific sites.
Daibata
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M
Department of Pharmacology, University of Massachusetts Medical School, Worcester 01655.
Humphreys
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Sairenji
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T
D002460:Cell Line; D000242:Cyclic AMP / Q000502:physiology; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D004854:Herpesvirus 4, Human / Q000378:metabolism*; D066298:In Vitro Techniques; D010449:Peptide Mapping; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D015534:Trans-Activators / Q000378:metabolism; D014764:Viral Proteins / Q000378:metabolism; D014779:Virus Replication
C063676:BZLF1 protein, Herpesvirus 4, Human; D004268:DNA-Binding Proteins; D010750:Phosphoproteins; D015534:Trans-Activators; D014764:Viral Proteins; D010768:Phosphoserine; D000242:Cyclic AMP