Stimulation of RAR alpha activation function AF-1 through binding to the general transcription factor TFIIH and phosphorylation by CDK7.
The activity of the N-terminal activation function AF-1 of RAR alpha1 is abrogated upon mutation of a phosphorylatable serine residue (Ser-77). Recombinant RAR alpha was phosphorylated by a variety of proline-directed protein kinases in vitro. However, only the coexpression of cdk7 stimulated Ser-77 phosphorylation in vivo and enhanced transactivation by RAR alpha, but not by a S77A RAR mutant. Both free CAK (cdk7, cyclin H, MAT1) and the CAK-containing general transcription factor TFIIH phosphorylated Ser-77 in vitro. Furthermore RAR alpha bound free CAK and purified TFIIH in vitro, and RAR alpha-TFIIH complexes could be isolated from HeLa nuclear extracts. These findings represent the first example of activation of a transactivator through binding to and phosphorylation by a general transcription factor.
Rochette-Egly
C
C
Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Université Louis Pasteur, Collège de France, Illkirch, Strasbourg.
Adam
S
S
Rossignol
M
M
Egly
J M
JM
Chambon
P
P
D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002467:Cell Nucleus / Q000378:metabolism; D018844:Cyclin-Dependent Kinases; D004265:DNA Helicases / Q000378:metabolism; D019281:Dimerization; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D017354:Point Mutation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D018168:Receptors, Retinoic Acid / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D000072482:Retinoic Acid Receptor alpha; D016415:Sequence Alignment; D012694:Serine; D015534:Trans-Activators / Q000378:metabolism*; D051758:Transcription Factor TFIIH; D014157:Transcription Factors / Q000378:metabolism*; D019473:Transcription Factors, TFII; D015533:Transcriptional Activation; D014162:Transfection; D000095043:Cyclin-Dependent Kinase-Activating Kinase
C000607071:RARA protein, human; D018168:Receptors, Retinoic Acid; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D000072482:Retinoic Acid Receptor alpha; D015534:Trans-Activators; D014157:Transcription Factors; D019473:Transcription Factors, TFII; D051758:Transcription Factor TFIIH; D012694:Serine; D017346:Protein Serine-Threonine Kinases; D018844:Cyclin-Dependent Kinases; D004265:DNA Helicases; D000095043:Cyclin-Dependent Kinase-Activating Kinase; C000722416:CDK7 protein, human