Claudia Hrastnik

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Nano-electrospray ionization tandem mass spectrometry (nano-ESI-MS/MS) was employed to determine qualitative differences in the lipid molecular species composition of a comprehensive set of organellar membranes, isolated from a single culture of Saccharomyces cerevisiae cells. Remarkable differences in the acyl chain composition of biosynthetically related(More)
Large parts of the endoplasmic reticulum of the yeast, Saccharomyces cerevisiae, are located close to intracellular organelles, i.e. mitochondria and the plasma membrane, as shown by fluorescence and electron microscopy. Here we report the isolation and characterization of the subfraction of the endoplasmic reticulum that is closely associated with the(More)
The aim of the project EUROFAN (European Functional Analysis Network) is to elucidate the function of unknown genes of the yeast Saccharomyces cerevisiae at a large scale. Functional analysis is based on general and specific tests with yeast deletion strains. A prerequisite for these studies is a profound knowledge of the biochemistry and cell biology of(More)
The yeast ERG4 gene encodes sterol C-24(28) reductase which catalyzes the final step in the biosynthesis of ergosterol. Deletion of ERG4 resulted in a complete lack of ergosterol and accumulation of the precursor ergosta-5,7,22,24(28)-tetraen-3beta-ol. An erg4 mutant strain exhibited pleiotropic defects such as hypersensitivity to divalent cations and a(More)
Lipids are essential components of all living cells because they are obligate components of biological membranes, and serve as energy reserves and second messengers. Many but not all genes encoding enzymes involved in fatty acid, phospholipid, sterol or sphingolipid biosynthesis of the yeast Saccharomyces cerevisiae have been cloned and gene products have(More)
Lipid particles of the yeast Saccharomyces cerevisiae are storage compartments for triacylglycerols (TAG) and steryl esters (STE). Four gene products, namely the TAG synthases Dga1p and Lro1p, and the STE synthases Are1p and Are2p contribute to storage lipid synthesis. A yeast strain lacking the four respective genes is devoid of lipid particles thus(More)
Lanosterol C-14 demethylase Erg11p of the yeast Saccharomyces cerevisiae catalyzes the enzymatic step following formation of lanosterol by the lanosterol synthase Erg7p in lipid particles (LP). Localization experiments employing microscopic inspection and cell fractionation revealed that Erg11p in contrast to Erg7p is associated with the endoplasmic(More)
The unassigned open reading frame YDL142c was identified to code for cardiolipin synthase, Cls1p. A cls1 deletion strain is viable on glucose, galactose, ethanol, glycerol and lactate containing media, although the growth rate on non-fermentable carbon sources is decreased. Mitochondria of the cls1 mutant are devoid of cardiolipin but accumulate the(More)
In the yeast, Saccharomyces cerevisiae, similar to higher eukaryotes most phospholipids are synthesized in microsomes. Mitochondria contribute to the cellular biosynthesis of phospholipids insofar as they harbor phosphatidylethanolamine decarboxylase, and enzymes of phosphatidylglycerol and cardiolipin synthesis. In this paper we present evidence that(More)
Fatty acyl esters of the yeast specific sterol, ergosterol, are exclusively stored in lipid particles. Under conditions of sterol deficiency, e.g., in the presence of terbinafine, an inhibitor of fungal squalene epoxidase, steryl esters are hydrolyzed, and sterols are set free for membrane formation. Lipid particles do not contain steryl-ester hydrolase(More)