Membrane engineering of S. cerevisiae targeting sphingolipid metabolism

AbstractThe sustainable production of fuels and chemicals using microbial cell factories is now well established. However, many microbial production processes are still limited in scale due to inhibition from compounds that are present in the feedstock or are produced during fermentation. Some of these inhibitors interfere with cellular membranes and change the physicochemical properties of the membranes. Another group of molecules is dependent on their permeation rate through the membrane for their inhibition. We have investigated the use of membrane engineering to counteract the negative effects of inhibitors on the microorganism with focus on modulating the abundance of complex sphingolipids in the cell membrane ofSaccharomyces cerevisiae. Overexpression ofELO3, involved in fatty acid elongation, andAUR1, which catalyses the formation of complex sphingolipids, had no effect on the membrane lipid profile or on cellular physiology. Deletion of the genesORM1andORM2, encoding negative regulators of sphingolipid biosynthesis, decreased cell viability and considerably reduced phosphatidylinositol and complex sphingolipids. Additionally, combiningELO3andAUR1overexpression withorm1/2Δimproved cell viability and increased fatty acyl chain length compared with onlyorm1/2Δ. These findings can be used to further study the sphingolipid metabolism, as well as giving guidance in membrane engineering.