BINDING OF TAFS TO CORE ELEMENTS DIRECTS PROMOTER SELECTIVITY BY RNA-POLYMERASE-II

The mechanisms that govern core promoter recognition and basal transcr iption efficiency remain poorly understood. Here, we have assessed the potential role of TAFs and the TFIID complex in directing basal promo ter function. Reconstituted transcription reactions revealed the abili ty of TFIID versus TBP to discriminate between distinct core promoters . A comparison of different partial TBP-TAF assemblages established th at a trimeric TBP-TAF(II)250-TAF(II)150 complex is minimally required for efficient utilization of the initiator and downstream promoter ele ments. Depending on the promoter structure, TAFs can increase or decre ase the stability of TFIID-promoter interactions. These findings sugge st that TAFs play a critical role in promoter selectivity and transcri ption regulation through direct contacts with core promoter elements.