The VP16 transcription activation domain is functional when targeted to a promoter-proximal RNA sequence.
Among eukaryotic transcription trans-activators, the human immunodeficiency virus type 1 (HIV-1) Tat protein is exceptional in that its target site TAR is an RNA rather than a DNA sequence. Here, we confirm that fusion of Tat to the RNA-binding domain of the HIV-1 Rev protein permits the efficient activation of an HIV-1 long terminal repeat (LTR) promoter in which critical TAR sequences have been replaced by RNA sequences derived from the HIV-1 Rev response element (RRE). An RRE target sequence as small as 13 nucleotides is shown to form an effective in vivo target for Rev binding. More important, a fusion protein consisting of Rev attached to the VP16 transcription activation domain was also observed to efficiently activate the HIV-1 LTR from this nascent RNA target. These data demonstrate that trans-activation of transcription by acidic activation domains does not require a stable interaction with the promoter DNA and suggest that VP16, like Tat, can act on steps subsequent to the formation of the HIV-1 LTR preinitiation complex. The finding that the activation domains of VP16 and Tat are functionally interchangeable raises the possibility that these apparently disparate viral trans-activators may nevertheless act via similar mechanisms.
Tiley
L S
LS
Howard Hughes Medical Institute, Duke University Medical Center, Durham, North Carolina 27710.
Madore
S J
SJ
Malim
M H
MH
Cullen
B R
BR
D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics / Q000378:metabolism; D015694:Gene Products, rev / Q000302:isolation & purification / Q000378:metabolism*; D015696:Gene Products, tat / Q000302:isolation & purification / Q000378:metabolism*; D015757:Genes, rev; D015756:Genes, tat; D016325:HIV Long Terminal Repeat; D015497:HIV-1 / Q000235:genetics* / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides; D011401:Promoter Regions, Genetic; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism*; D015183:Restriction Mapping; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D054321:rev Gene Products, Human Immunodeficiency Virus; D054322:tat Gene Products, Human Immunodeficiency Virus
D015694:Gene Products, rev; D015696:Gene Products, tat; D009838:Oligodeoxyribonucleotides; D012367:RNA, Viral; D015534:Trans-Activators; D054321:rev Gene Products, Human Immunodeficiency Virus; D054322:tat Gene Products, Human Immunodeficiency Virus; D015500:Chloramphenicol O-Acetyltransferase