UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

TBP and its diversified role in transcription initiation Kwan, James


Transcription by RNA Polymerases (RNA Pol) is initiated by the hierarchal assembly of the Pre- Initiation Complex (PIC) at the promoters of genes. TATA-box binding protein (TBP) is believed to be the first factor to bind onto RNA Pol II promoters to recruit the other General Transcription Factors (GTFs) for PIC formation and also plays a role in recruiting the necessary factors in the other two major eukaryotic RNA Polymerase (RNA Pol I and RNA Pol III). Decades of in vitro biochemical and in vivo yeast research have shown that TBP is essential for transcription initiation for the major three eukaryotic RNA Polymerases, but serendipitous TBP research in multicellular eukaryotes suggest otherwise. In this thesis, we examined the effects of TBP depletion in mouse Embryonic Stem Cells (mESCs) and report that acute depletion of TBP has no global effect on ongoing RNA Pol II and RNA Pol I transcription, but acute depletion of TBP severely impairs RNA Pol III transcription. We showed that this RNA Pol I and RNA Pol II TBP-independent transcription mechanism is not due to the TBP paralog TRF2 and that for RNA Pol II, the TFIID complex can still form and bind onto promoter DNA, despite having altered binding dynamics. Additionally, we showed that TBP binds onto RNA Pol I promoters and mitotically bookmark these genes for efficient transcriptional reactivation following mitosis and depletion of TBP impairs this process. Collectively, these results show how the transcriptional role of TBP has diverged throughout evolution and the potential mechanism of TBP-independent RNA Polymerase transcription in mESCs.

Item Media

Item Citations and Data


Attribution-NonCommercial-NoDerivatives 4.0 International