Enzymes of Lipid Synthesis in the Yeast
Synthesis of lipids, lipid assembly into organelle membranes and lipid storage are important biochemical and cell biological processes. In our laboratory, we use the yeasts Saccharomyces cerevisiae and Pichia pastoris as model organisms to address these questions. The advantage of these microorganisms is easy handling by cultivation conditions and molecular biological methods. Importantly, many results obtained with these unicellular organisms can be transformed to higher eukaryotes.
Enzymes of lipid synthesis in the yeast are distributed among the endoplasmic reticulum (ER), mitochondria, the Golgi and the so-called lipid droplets. However, lipids formed in one of these organelles are not only restricted to their site of synthesis, but also migrate to other organelles where they are assembled into the respective organelle membrane(s). Maintenance of organelle lipid profiles is a highly important issue because it is linked to structure and function of the respective subcellular compartment. Strict coordination and regulation of biosynthetic and translocation processes are prerequisite for cellular lipid homeostasis.
Specific aspects studied currently in our group are phospholipid assembly and homeostasis in mitochondrial membranes with emphasis on the role of phosphatidylethanolamine. The majority of mitochondrial phosphatidylethanolamine is synthesized by the mitochondrial phosphatidylserine decarboxylase 1 (Psd1p). Therefore, this enzyme deserves our specific attention. Studies addressing the structure-function relationship of Psd1p in some detail will be main tasks of our future research in this field. The other major project in our laboratory deals with lipid storage in yeast lipid droplets. The most important non-polar storage lipids of the yeast are triacylglycerols and steryl esters. Current investigations are focused on the interplay of the non-polar lipid biosynthetic and degradation machineries. Enzymes involved in these processes are acyltransferases and lipases/hydrolases, respectively. Major goals of our future research in this field will be investigations of regulatory aspects at the levels of gene expression, enzyme activation/inhibition and protein targeting to understand the life cycle and homeostasis of non-polar lipids in more detail. Biochemical, cell biological and molecular biological methods supplemented by genome, proteome and lipidome analyses will be employed in this work.
Laboratory know-how and infrastructureThe proposed projects will be carried out at the Institute of Biochemistry, Graz University of Technology. The equipment required for these projects such as centrifuges, photometer, chromatographic and electrophoresis equipment, HPLC, microscopes and liquid scintillation counter will be provided by the institution. The know-how of the applicant’s laboratory in yeast lipid and biomembrane research is well established. Isolation and characterization of organelles, enzyme measurements including radiochemical techniques, methods of lipid and protein analysis and fundamental methods of yeast microbiology, genetics and molecular biology are standard in our laboratory. Current co-workers of the applicant are well trained in these methods. Investigations of our group are mainly devoted to fundamental research. PhD students from the applicant’s laboratory are educated within the framework of the Doctoral School for Molecular Biosciences and Biotechnology, a joint venture of the University of Graz and the Graz University of Technology. The applicant is Director of this Doctoral School at the Graz University of Technology.