Selective inhibition of activated but not basal transcription by the acidic activation domain of VP16: evidence for transcriptional adaptors.
The interaction between the chimeric activator GAL4-VP16, consisting of the DNA binding domain of GAL4 and the acidic activation domain of VP16, and its target in the transcriptional machinery was studied in vitro. GAL4-VP16 stimulated transcription from a promoter bearing GAL4 sites, and greatly inhibited transcription from a promoter bearing binding sites for the dA:dT activator and from a basal promoter bearing only a TATA box. Mutations in the acidic domain that reduced activation from the GAL4 site promoter also reduced inhibition from the dA:dT promoter, indicating a similar interaction between VP16 and its target in both processes. Strikingly, if the DNA binding domain of GAL4-VP16 was occupied by a GAL4 site oligonucleotide, the protein inhibited activation by the dA:dT activator but did not inhibit basal transcription. We propose that, under these conditions, GAL4-VP16 acted to titrate an "adaptor" that bridges an interaction between the upstream activator and the basic transcriptional machinery at the TATA box.
Berger
S L
SL
Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
Cress
W D
WD
Cress
A
A
Triezenberg
S J
SJ
Guarente
L
L
D001665:Binding Sites; D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins; D004926:Escherichia coli / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D008957:Models, Genetic; D010750:Phosphoproteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D010957:Plasmids; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000302:isolation & purification / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D018139:Simplexvirus / Q000235:genetics; D013698:Templates, Genetic; D015534:Trans-Activators / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C052130:GAL4 protein, S cerevisiae; D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors