BINDING OF BASAL TRANSCRIPTION FACTOR TFIIH TO THE ACIDIC ACTIVATION DOMAINS OF VP16 AND P53

Acidic transcriptional activation domains function well in both yeast and mammalian cells, and some have been shown to bind the general tran scription factors TFIID and TFIIB. We now show that two acidic transac tivators, herpes simplex virus VP16 and human p53, directly interact w ith the multisubunit human general transcription factor TFIIH and its Saccharomyces cerevisiae counterpart, factor b. The VP16- and p53-bind ing domains in these factors lie in the p62 subunit of TFIIH and in th e homologous subunit, TFB1, of factor b. Point mutations in VP16 that reduce its transactivation activity in both yeast and mammalian cells weaken its binding to both yeast and human TFIIH. This suggests that b inding of activation domains to TFIIH is an important aspect of transc riptional activation.