Department of Molecular Physiology and Biophysics, Vanderbilt University, School of Medicine, Nashville, TN 37232-0615, USA-
Abstract: In vivo studies have previously shown that Saccharomyces cerevisiae ribosomal protein -RP- gene expression is controlled by the transcription factor repressor activator protein 1 -Rap1p- in a TFIID-dependent fashion- Here we have tested the hypothesis that yeast TFIID serves as a coactivator for RP gene transcription by directly interacting with Rap1p- We have found that purified recombinant Rap1p specifically interacts with purified TFIID in pull-down assays, and we have mapped the domains of Rap1p and subunits of TFIID responsible- In vitro transcription of a UAS-RAP1- enhancer-driven reporter gene requires both Rap1p and TFIID and is independent of the Fhl1p-Ifh1p coregulator- UAS-RAP1- enhancer-driven transactivation in extracts depleted of both Rap1p and TFIID is efficiently rescued by addition of physiological amounts of these two purified factors but not TATA-binding protein- We conclude that Rap1p and TFIID directly interact and that this interaction contributes importantly to RP gene transcription-