DNA-TEMPLATE AND ACTIVATOR-COACTIVATOR REQUIREMENTS FOR TRANSCRIPTIONAL SYNERGISM BY DROSOPHILA BICOID

The template and coactivator requirements for synergistic transcriptio n directed by a single activator, Bicoid (BCD), bound to multiple site s have been determined. Mutagenesis studies in combination with protei n binding experiments and reconstituted transcription reactions identi fied two independent activation domains of BCD that target different c oactivator subunits (TAF(II)110 and TAF(II)60) of the basal transcript ion factor IID (TFIID). The presence of both coactivators is required for BCD to recruit the TATA binding protein (TBP)-TAF complex to the p romoter and direct synergistic activation of transcription. Thus, cont act between multiple activation domains of BCD and different targets w ithin the TFIID complex can mediate transcriptional synergism.