The three-dimensional spatial architecture of chromosomes is integrally connected to chromatin function. Budding yeast telomeres cluster at the nuclear periphery, the ribosomal genes are localised to the nucleolus, tRNA genes may also tend to localise to the nucleolus or centromeres, while the later cluster near the spindle pole body. Recently, in the fission yeast Schizosaccharomyces pombe, a novel role has been revealed for the RNA polymerase III transcriptional apparatus, and TFIIIC in particular, in chromosome spatial organisation and boundary function. In this project, I investigate whether Saccharomyces cerevisiae Extra TFIIIC (ETC) sites, which bind the TFIIIC transcription factor but do not recruit RNA polymerase III, act to position chromosomal domains. I show that six of the eight known S. cerevisiae ETC sites localise predominantly at the nuclear periphery. An ETC site retains its tethering function when moved to a new chromosomal location. TFIIIC binding is necessary for peripheral localisation, since deleting the TFIIIC binding consensus ablates ETC site peripheral positioning. I find that any of the six TFIIIC subunits can drive peripheral tethering, suggesting that the TFIIIC complex is central to the positioning mechanism. Interestingly, anchoring of ETC sites to the nuclear periphery also requires Mps3, a Sad1-UNC-84 domain protein that spans the inner nuclear membrane. Moreover, I show that the mechanism of ETC site peripheral tethering requires chromatin remodelling proteins, and in particular Histone 3 - Lysine 56 (H3K56) acetylation. Finally, I investigate the biological function of ETC sites and examine the connection between this biological function and their ability to anchor at the nuclear periphery. In summary, TFIIIC and Mps3 together position a new class of genomic loci crucial for correct spatial organisation of S. cerevisiae chromosomes.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:540492 |
| Date | January 2010 |
| Creators | Botsios, Sotirios |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=165975 |
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