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Control of mating in Schizosaccharomyces pombe

Pereira, Paulo; (2002) Control of mating in Schizosaccharomyces pombe. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

Activation of key transcriptional regulators often results in profound changes in the cellular gene expression profile, committing cells to a differentiation pathway. The Schizosaccharomyces pombe Ste11 protein is a crucial regulator of the mating and meiotic program. Several genes required for mating-type specific gene expression, conjugation, and meiosis are transcriptionally activated after nitrogen starvation in a Ste11-dependent manner. The aim of this thesis was to extend our understanding of how the HMG-box containing Ste11 is regulated at the protein level, and to identify and characterise novel Ste11-target genes involved in the mating pathway. Using a one-hybrid assay, I have shown that Ste11 protein is a strong transcriptional activator, and was able to map its transcriptional activation domain to the C-terminal region. Interestingly, induction of Ste11 target genes upon nitrogen starvation could neither be attributed to regulation of the transcriptional activity of this domain, nor to changes in Ste11 subcellular localisation. Knowing the DNA sequence necessary for Ste11 binding and for starvation-mediated transcriptional induction, I searched the S. pombe genome database for putative Ste11 target genes. One of the genes found was rgs1, a member of the Regulator of G-protein Signalling (RGS) family, rgs1 expression requires both a Ste11-mediated starvation signal and the pheromone-induced activation of the Byr2/Byr1/Spk1 MAPK pathway. Disruption of the rgs1 gene results in sensitivity to pheromone and in a mating defect. Rgs1 localises to the nucleus and cytoplasm, which is not altered during pheromone treatment. Importantly, Rgs1 function requires its C-terminal RGS domain, as well as a central DEP domain and a novel N-terminal homology domain. In summary, Rgs1 negatively regulates pheromone signalling during mating, acting in a negative feedback loop that is essential for the mating process. Taken together, these results extend our understanding of the mechanisms regulating the mating pathway in the fission yeast.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Control of mating in Schizosaccharomyces pombe
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Thesis digitised by ProQuest.
Keywords: Biological sciences; Fission yeast
URI: https://discovery.ucl.ac.uk/id/eprint/10098673
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