Characterization of UDP-glucose: ceramide glucosyltransferases from different organisms

M Leipelt, DC Warnecke, B Hube, U Zähringer, E Heinz - 2000 - portlandpress.com
M Leipelt, DC Warnecke, B Hube, U Zähringer, E Heinz
2000portlandpress.com
Cerebrosides are typical membrane lipids of many organisms. They occur in plants, fungi,
animals, humans and some prokaryotes. Almost all of our knowledge on the physiological
functions of cerebrosides results from experimental data obtained with mammalian cells.
However, very little is known about the roles played by these lipids in plants and fungi. To
initiate such investigations we have cloned and characterized a ceramide
glucosyltransferase from the yeast Candida albicans. Functional expression of this gene in …
Cerebrosides are typical membrane lipids of many organisms. They occur in plants, fungi, animals, humans and some prokaryotes. Almost all of our knowledge on the physiological functions of cerebrosides results from experimental data obtained with mammalian cells. However, very little is known about the roles played by these lipids in plants and fungi. To initiate such investigations we have cloned and characterized a ceramide glucosyltransferase from the yeast Candida albicans. Functional expression of this gene in Saccharomyces cerevisiae led to the accumulation of new glycolipids which were not present in wildtype baker's yeast. They were identified by MS and NMR spectroscopy as β-D-glucopyranosyl ceramides. The ceramide moieties of these cerebrosides comprised phytosphinganine and mainly long-chain (C26) α-hydroxy fatty acids in amide linkage. We also generated a ceramide glucosyltransferase-knock-out strain of C. albicans which was devoid of cerebrosides. The viability of this mutant showed that for this organism glucosyl ceramides are not essential for vegetative growth on complete or minimal media. In addition, we have cloned and functionally expressed one of the three putative glucosylceramide synthases from Caenorhabditis elegans as well as a corresponding enzyme from Pichia pastoris.
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