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.

Grant Number: 5R01GM146803-04
NIH Institute/Center: NIH
Principal Investigator: Athar Ansari