A new paradigm of general transcription factor TFIIB functionality in termination and promoter directionality

Project Summary Regulated transcription of genes is essential for cell proliferation, differentiation and viability. Any misregulation may lead to a disease or a developmental abnormality. The transcription cycle of eukaryotic genes consists of multiple steps. The accomplishment of each of these steps requires a number of accessory factors. The initiation of transcription by RNAPII requires gene-specific factors and the general transcription factors (GTFs). The conventional view is that the general transcription factors (GTFs) operate exclusively at the initiation step of transcription. Many recent studies have challenged this dogma. The successful execution of the transcription cycle requires some GTFs to function at the termination step as well. Evidence from my laboratory and others has demonstrated that the general transcription factor TFIIB has an evolutionarily conserved role in termination of transcription. My laboratory has further implicated TFIIB in promoter directionality. Our preliminary results strongly suggest that the mechanistic basis of TFIIB action is, in both cases, dependent on its ability to interact with the termination factors and facilitate their recruitment on the gene. An investigation into the role of TFIIB in termination and directionality is critical to understanding of transcriptional regulation in eukaryotes, and may provide clues into the role TFIIB plays in several diseases. The overall objective of this application is to determine the prevalence and the molecular basis underlying termination of transcription and promoter directionality by TFIIB. The central hypothesis of this application is that TFIIB is involved in termination and promoter directionality of at least a subset of genes. We propose that these apparently unrelated processes rely on the ability of TFIIB to recruit termination factors. To accomplish the objectives of the proposal, we propose the following Specific Aims: (1) Genomewide analysis of TFIIB functions in termination and promoter directionality; (2) Elucidate the molecular basis underlying role of TFIIB in termination and promoter directionality; (3) Purification and characterization of the holo-TFIIB complex. The successful completion of this proposal will enable us to comprehend the role of transcription factors in the broader context, and will serve as a paradigm for understanding the coordination among steps of the transcription cycle in yeast and mammalian systems.