Yeast Sphingolipids – Structure, Biological Importance and Metabolism
Mirela Bauman1*, Marko Mesarić1 and Vladimir Marić2
1Department of Chemistry and Biochemistry, School of Medicine, University of Zagreb, Šalata 3, HR–10000 Zagreb, Croatia
2Department of Biochemical Engineering, Faculty of Food Science and Biotechnology, University of Zagreb, Pierottijeva 6, 10000 Zagreb, Croatia
Article history:
Received September 11, 1998
Accepted February 15, 1999
Key words:
yeast, sphingolipids, degradation, biosynthesis
Summary:
Sphingolipids, detected and named by J. L. W. Thudicum more than a hundred years ago, have a common long chain sphingoid base. In most mammals this base is sphingosine. In yeasts, phytosphingosine occurs. Complex sphingolipids are made of sphingoid base to which a fatty acid is linked via an amide bond. Yeast sphingolipids are involved in membrane signaling, regulation of cell wall biosynthesis, phospholipid biosynthesis and binding of cell surface glycoproteins. Besides, they are proven to play important roles in signal transduction during the heat stress response, regulation of calcium homeostasis or components in calcium-mediated signaling pathways and in regulation of the cell cycle. The key reaction in yeasts sphingolipids biosynthesis is condensation of palmitoyl-CoA with serine yielding D-3-ketosphinganine. This reaction is catalyzed by serine palmitoyltransferase; the mechanism by which yeast cells regulate activity of the enzyme and the concentration of sphingolipids is still being investigated. Little is known about sphingolipids breakdown pathways in yeasts. A form of mammalian sphingomyelinase was found to exist in Saccharomyces cerevisiae. There are no data on the activity of ceramidase in the yeast. Secretory pathway is regarded the main pathway of sphingolipid transport in the cell; Golgi appears to be the branching point in this process.
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