c-Fos-induced activation of a TATA-box-containing promoter involves direct contact with TATA-box-binding protein.
Transcriptional activation in eukaryotes involves protein-protein interactions between regulatory transcription factors and components of the basal transcription machinery. Here we show that c-Fos, but not a related protein, Fra-1, can bind the TATA-box-binding protein (TBP) both in vitro and in vivo and that c-Fos can also interact with the transcription factor IID complex. High-affinity binding to TBP requires c-Fos activation modules which cooperate to activate transcription. One of these activation modules contains a TBP-binding motif (TBM) which was identified through its homology to TBP-binding viral activators. This motif is required for transcriptional activation, as well as TBP binding. Domain swap experiments indicate that a domain containing the TBM can confer TBP binding on Fra-1 both in vitro and in vivo. In vivo activation experiments indicate that a GAL4-Fos fusion can activate a promoter bearing a GAL4 site linked to a TATA box but that this activity does not occur at high concentrations of GAL4-Fos. This inhibition (squelching) of c-Fos activity is relieved by the presence of excess TBP, indicating that TBP is a direct functional target of c-Fos. Removing the TBM from c-Fos severely abrogates activation of a promoter containing a TATA box but does not affect activation of a promoter driven only by an initiator element. Collectively, these results suggest that c-Fos is able to activate via two distinct mechanisms, only one of which requires contact with TBP. Since TBP binding is not exhibited by Fra-1, TBP-mediated activation may be one characteristic that discriminates the function of Fos-related proteins.
Metz
R
R
Department of Molecular Biology, Bristol-Myers-Squibb Pharmaceutical Research Institute, Princeton, New Jersey 08534-4000.
Bannister
A J
AJ
Sutherland
J A
JA
Hagemeier
C
C
O'Rourke
E C
EC
Cook
A
A
Bravo
R
R
Kouzarides
T
T
D017500:Adenovirus E1A Proteins / Q000235:genetics; D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D017405:Herpes Simplex Virus Protein Vmw65 / Q000235:genetics; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D035181:TATA-Box Binding Protein; D035362:Transcription Factor TFIID; D014157:Transcription Factors / Q000378:metabolism*; D000099169:Fos-Related Antigen 1
D017500:Adenovirus E1A Proteins; D004268:DNA-Binding Proteins; D017405:Herpes Simplex Virus Protein Vmw65; D046911:Macromolecular Substances; D009838:Oligodeoxyribonucleotides; D016760:Proto-Oncogene Proteins c-fos; D035181:TATA-Box Binding Protein; D035362:Transcription Factor TFIID; D014157:Transcription Factors; D000099169:Fos-Related Antigen 1