UC Riverside

Transcription of protein coding genes and some non-coding RNAs relies on RNA polymerase II (pol II). Positioning the polymerase at the correct location at the start of a gene is aided by a series of general transcription factors (GTFs): TFIIA, B, D, E, F, and H. Together with pol II, these factors form the preinitiation complex. TFIID is first to recognize and bind to a gene promoter and helps facilitate recruitment of the other components. TAF1 is the largest subunit of TFIID and aside from its role as a GTF, it functions to regulate gene specific transcription. TAF1 has intrinsic kinase activity and has been shown to phosphorylate other members of the general transcription machinery as well as the tumor suppressor p53. Previous studies have shown that phosphorylation of p53 by TAF1 leads to dissociation from the p21 promoter and termination of transcription. Those studies also found that TAF1 kinase responds to fluctuations in cellular ATP, having a KmATP of 1.9mM. In the early stages following DNA damage, cells undergo cellular ATP depletion which was found to effect TAF1-mediated phosphorylation of p53 giving rise to a regulatory mechanism of p21 transcription. The studies presented here investigate the possibility that TAF1 regulates other sequence specific transcription factors, like p53, through phosphorylation. The work described in this dissertation includes the purification of many proteins for in vitro characterization of two novel TAF1 kinase targets, E2F1 and FOXM1. Furthermore, this research investigates the effect that TAF1-mediated phosphorylation has on E2F1 and FOXM1 promoter occupancy and transcription of target genes. My studies provide new insights into how TAF1 regulates gene-specific transcription through phosphorylation, broadening our understanding of this complex GTF.