Transcription termination by RNA polymerase II

• Main Author: White, Eleanor
• Other Authors: Proudfoot, Nicholas ; Dye, Michael
• Published: University of Oxford 2011
• Subjects: 572.8845
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.558432

RNA Polymerase II (Pol I1) is responsible for the transcription of all protein-encoding genes. Pol II termination is dependent on RNA processing signals (both terminal intron splice sites, and cleavage and polyadenylation signals) as well as specific terminator elements located downstream of the poly(A) site. Detailed analysis of the human ~- globin gene terminator has shown that it contains a sequence-specific region that promotes rapid Co-Transcriptional Cleavage (CoTC) of the nascent transcript - an essential but not well understood step in the human ~-globin gene termination process. In the first part of this thesis, the role of sequences within this CoTC-mediated terminator element in the termination process is investigated. Analysis of mutant terminator sequences indicate that homopolymer A tracts are important for Pol II termination. The second part of this study focuses on identifying the activity responsible for CoTC, by using the yeast S. pombe as a tool for genetic analysis. The results indicate that the human ~-globin gene terminator is inefficient in S. pombe, suggesting that a mammalian specific factor(s) are required. In the final part of this study, I describe an investigation into the possibility that the exosome subunit Dis3 or the RNase III enzyme Dicer are involved in CoTC mediated transcription termination. While Dis3 is not involved in the CoTC process my results on Dicer may imply a significant role. Lastly, I present a preliminary investigation into the effect of pre-mRNA processing and the carboxyl terminal domain (CTD) of Po 1 II on CoTC activity.