INTERACTION BETWEEN AN ACIDIC ACTIVATOR AND TRANSCRIPTION FACTOR-TFIIB IS REQUIRED FOR TRANSCRIPTIONAL ACTIVATION

HOW eukaryotic promoter-specific activator proteins (activators) stimu late transcription is a central question. We have previously shown tha t an acidic activator can directly interact with the general transcrip tion factor TFIIB and increase its stable assembly into a preinitiatio n complex1,2. We have proposed that this increase in TFIIB assembly is at least part of the mechanism by which an acidic activator functions 1,2. A prediction of this hypothesis is that a TFIIB mutant unable to interact with an acidic activator could not support activated transcri ption, and here we present experiments that verify this prediction. In conjunction with previous studies, our results argue that interaction between an acidic activator and TFIIB is necessary for transcriptiona l activation.