Varicella-zoster virus open reading frame 10 protein, the herpes simplex virus VP16 homolog, transactivates herpesvirus immediate-early gene promoters.
The varicella-zoster virus (VZV) open reading frame 10 (ORF10) protein is the homolog of the herpes simplex virus type 1 (HSV-1) protein VP16. These are two virion tegument proteins that have extensive amino acid sequence identity in their amino-terminal and middle domains. ORF10, however, lacks the acidic carboxy terminus which is critical for transactivation by VP16. Earlier studies showed that VZV ORF10 does not form a tertiary complex with the TAATGARAT regulatory element (where R is a purine) with which HSV-1 VP16 interacts, suggesting that ORF10 may not have transactivating ability. Using transient-expression assays, we show that VZV ORF10 is able to transactivate VZV immediate-early (IE) gene (ORF62) and HSV-1 IE gene (ICP4 and ICP0) promoters. Furthermore, cell lines stably expressing ORF10 complement the HSV-1 mutant in1814, which lacks the transactivating function of VP16, and enhance the de novo synthesis of infectious virus following transfection of HSV-1 virion DNA. These results indicate that ORF10, like its HSV-1 homolog VP16, is a transactivating protein despite the absence of sequences similar to the VP16 carboxy-terminal domain. The transactivating function of the VZV ORF10 tegument protein may be critical for efficient initiation of viral infection.
Medical Virology Section, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland 20892.
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Moriuchi
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Moriuchi
S E
SE
Straus
J I
JI
Cohen
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D004279:DNA, Viral; D004268:DNA-Binding Proteins; D005816:Genetic Complementation Test; D014645:Herpesvirus 3, Human / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity; D006801:Humans; D017874:Immediate-Early Proteins; D008969:Molecular Sequence Data; D016366:Open Reading Frames / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D018139:Simplexvirus / Q000235:genetics; D015533:Transcriptional Activation; D014162:Transfection; D014170:Transformation, Genetic; D014764:Viral Proteins / Q000096:biosynthesis / Q000235:genetics*; D014774:Virulence; D014779:Virus Replication
D004279:DNA, Viral; D004268:DNA-Binding Proteins; C045462:ICP8 protein, Simplexvirus; C050678:IE1 protein, Human herpesvirus 1; D017874:Immediate-Early Proteins; D014764:Viral Proteins