Transcriptional trans activators of human and simian foamy viruses contain a small, highly conserved activation domain.
The Bel-1 protein of human foamy virus is a potent transcriptional trans activator of its homologous long terminal repeat promoter element. Here, we demonstrate that Bel-1 can also efficiently activate gene expression when targeted to a heterologous promoter by fusion to the DNA-binding motif of the yeast GAL4 protein. Analysis of a series of deletion mutants of Bel-1 generated in this hybrid protein context suggests the presence of a single transcription activation domain that is fully contained within a discrete, approximately 30-amino-acid segment located proximal to the Bel-1 carboxy terminus. Although this short motif can be shown to function effectively in eukaryotic cells of mammalian, avian, and fungal origin, it does not bear any evident sequence homology to the known classes of eukaryotic activation domain. However, this Bel-1 activation domain was found to be fully conserved, in terms of both biological activity and location, in the distantly related Taf trans activator of simian foamy virus type 1.
Garrett
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Howard Hughes Medical Institute, Duke University Medical Center, Durham, North Carolina 27710.
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Bogerd
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Cullen
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D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins / Q000737:chemistry*; D005656:Fungal Proteins / Q000737:chemistry; D016325:HIV Long Terminal Repeat; D056488:Histone Chaperones; D006801:Humans; D011993:Recombinant Fusion Proteins; D012191:Retroviridae Proteins / Q000737:chemistry*; D029701:Saccharomyces cerevisiae Proteins; D016092:Spumavirus / Q000737:chemistry*; D013329:Structure-Activity Relationship; D015534:Trans-Activators / Q000737:chemistry*; D014157:Transcription Factors; D015533:Transcriptional Activation
D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C052130:GAL4 protein, S cerevisiae; D056488:Histone Chaperones; D011993:Recombinant Fusion Proteins; D012191:Retroviridae Proteins; C513473:SET protein, human; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C074061:bel1 protein, Human foamy virus