This work presents the investigation of fungal AdoMet-dependent methyltransferases. The first part of the dissertation focuses on two distinct methyltransferases with previously unknown functions in the budding yeast Saccharomyces cerevisiae and the human fungal pathogen Candida albicans. To characterize these enzymes I used a combinatorial approach that exploits contemporary high-throughput techniques available in yeast (chemical genetics, expression, lipid profiling and genetic interaction analysis) combined with rigorous biological follow-up. First, I showed that S. cerevisiae CRG1 (ScCRG1) is a small molecule methyltransferase that methylates cytotoxic drug cantharidin and is important for maintaining lipid homeostasis and actin cytoskeleton integrity in response to small-molecule cantharidin in the baker’s yeast. Similarly to ScCRG1, orf19.633 in the human fungal pathogen C. albicans (CaCRG1) methylates cantharidin and is important for GlcCer biosynthesis. I also demonstrated that CaCrg1 is a ceramide- and PIP-binding methyltransferase involved in Candida’s morphogenesis, membrane trafficking and fungal virulence. Together, the analysis of two genes in yeast illuminated the important roles of the novel small molecule methyltransferases in coupling drug response to lipid biosynthesis and fungal virulence. In the second part of my dissertation, I present the systematic characterization of the genetic architecture of the yeast methyltransferome by examining fitness of double-deletion methyltransferase mutants in standard and under environmental stress conditions. This analysis allowed me to describe specific properties of the methyltransferome network and to uncover functional relationships among methyltransferases inspiring multiple hypotheses and expanding the current knowledge of this family of enzymes.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/43639 |
| Date | 10 January 2014 |
| Creators | Lissina, Elena |
| Contributors | Nislow, Corey |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis, Dataset |
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