A mutational analysis of genes which confer resistance to the yeast K1 killer toxin has identified a number of components involved in the synthesis of a $ beta(1 to 6)$-linked glucan polymer found in the Saccharomyces cerevisiae extracellular matrix. The KRE9 gene is predicted to encode a 30 kDa serine/threonine rich cell wall protein, which is modified by O-glycosylation before being secreted at the cell surface where it likely functions in $ beta(1 to 6)$-glucan assembly. Null mutations in KRE9 lead to killer resistance, slow vegetative growth, and reduced cell wall $ beta(1 to 6)$-glucan levels which are 10 to 20% of wild type. A study of the KRE11 gene has revealed that its product, Kre11p, is a 63 kDa cytoplasmic protein which appears to be involved in the regulation of glucan assembly. Through genetic interactions and epistasis assignments with these and other KRE genes, the basis of a biosynthetic pathway for the synthesis of this extracellular matrix polymer has emerged. / A search for genes involved in the regulation of cell surface assembly has led to the identification of SKN7. Sequence analysis of Skn7p revealed a region of homology to the DNA-binding domains found on heat-shock transcription factors, and a distinct region of similarity to a large family of bacterial "two-component" signal-transduction proteins. Two-component systems have historically been confined to prokaryotic organisms, and the identification of SKN7 has raised the possibility that two-component signaling pathways involving phospho-histidine and phospho-aspartate transfer reactions may exist in higher eukaryotes. Skn7p appears to function in yeast as a nuclear localized two-component response regulator, whose transcriptional B activity is regulated through aspartic acid phosphorylation. The Skn7p signal transduction pathway may act in concert with the yeast PKC1-mediated MAP-kinase cascade, to regulate cellular growth events at the cell surface.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.28696 |
| Date | January 1994 |
| Creators | Brown, Jeffrey L., 1968- |
| Contributors | Bussey, H. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Biology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001467855, proquestno: NN05680, Theses scanned by UMI/ProQuest. |
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