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Title: 3' end processing and RNA polymerase II transcription termination in protein coding genes in the nematode C. elegans
Author: Zechner, Kerstin
ISNI:       0000 0004 2730 4565
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2011
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In all organisms studied so far, the recognition of a functional poly(A) site is essential for RNA polymerase II termination at the end of nearly all genes transcribed by this enzyme (Whitelaw and Proudfoot, 1986; Guo et al., 1995; Birse et al. 1997). A number of eukaryotes have some of their genes organised in polycistronic structures which resemble bacterial operons (Davis and Hodgson, 1997; Ganot et al., 2004; Spieth et al. 1993), and in C. elegans, approximately 20% of all genes are contained within these operon-like structures (Blumenthal et al., 2002). Here, functional poly(A) sites will be synthesised and recognised by RNA polymerase II at the end of each gene within the operon, however termination of the polymerase only occurs at the final gene of the polycistronic transcription unit In these studies, we analyse the halting of RN A polymerase II transcription at the end of monocistronic genes and furthermore observe how premature RNA polymerase II termination is prevented during polycistronic transcription in the nematode C. elegans. We predominantly make use of reverse transcriptase PCR-based techniques to examine these mechanisms. We show that a large increase in pre-mRNAs stretching into the 3' flank of genes can be detected in worms depleted of the riboexonuclease XRN-2, indicating that this enzyme may have a possible role in RNA pol II termination and 3' end formation in C. elegans. Furthermore, we provide evidence that the polymerase can read into telomeric structures in the nematode. Also, we demonstrate that an RNAi-mediated knockdown of the UI-70K subunit of the UI snRNP causes a drop in polycistronic transcripts, providing a link between cis- splicing and the prevention of premature RNA polymerase II termination at operon-internal poly(A) sites. Finally, we illustrate that operon-internal poly(A) sites are capable of directing efficient 3' end formation outside of a polycistronic background. Together, these findings provide valuable insights into the mechanisms involved in directing or preventing premature RNA polymerase II transcription termination at C. elegans poly(A) sites.
Supervisor: Furger, André Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: RNA polymerases ; Caenorhabditis elegans