Date of Award
Doctor of Philosophy (PhD)
Various in vivo and in vitro assays have been employed to analyze how activators communicate with the general transcription machinery to stimulate transcription. As a first step, I analyzed the function of distinct kinds of activation domains in yeast and human. The results showed that the proline-rich activation domain of CTF1 can, like acidic activation domains, activate transcription in yeast and human. Based on this, I compared the activation pathways by acidic and proline-rich activation domains in yeast and human. These detailed comparative approaches yielded clues to the fundamental aspects of transcriptional activation mechanism in eukaryotes: activators target TFIID (TBP)-TFIIB promoter complex formation in the preinitiation complex assembly process by inducing (or stabilizing) qualitative or quantitative alterations within TFIID (TBP)-TFIIB-promoter complexes that consequently enhance recruitment of downstream initiation factors. Consistent with this view, various activation domains have been demonstrated to have physical and functional interactions with TBP and/or TFIIB. Given the central role of TBP in transcriptional regulation, I also identified distinct TBP domains (or residues) important for different regulatory interactions including those with acidic activators, TFIIB, Dr1 (NC2) , Pol I- and Pol III- specific factors. These mutational analyses have provided an insight into how the interplay of many regulatory factors occurs on the surface of a target factor, TBP, to specify and regulate transcriptional activity. Furthermore, I investigated the essential features of the CTF1 proline-rich activation domain and showed that CTD-like sequences (Ser-Pro motifs) are important for activation, possibly by forming a β-turned omega (Ω) loop structure. Thus, the β-turn structure is likely to be a salient secondary structure in the activation domains in addition to a β- sheet structure which was previously proposed for acidic activation domains.
Kim, Tae Kook, "Eukaryotic Transcriptional Activation Mechanism: Protein-Protein Interactions" (1994). Student Theses and Dissertations. 373.