Moreover, several studies have shown that organisms like the yeast S. cerevisiae can tolerate great changes in their lipid composition, compensating for example for the absence of one lipid by overproduction of another, without notable effects on their viability [5,6]. Despite many mass spectrometry based lipidomics methods developed today [7], the current knowledge of the lipidome of eukaryotic organisms is still limited. As the lipidome of higher eukaryotic organisms consists of hundreds to

thousands of individual Inhibitors,research,lifescience,medical molecular species, a model organism is needed, which possesses a relatively simple lipidome, but still reflects the main biosynthetic and metabolic pathways of higher eukaryotic organisms. It should be easy to handle and also, if necessary, easy to manipulate. Another important Inhibitors,research,lifescience,medical criterion is a detailed knowledge on gene, protein and also lipid biosynthesis, which enables to fill gaps in the understanding of a complex biological network.

Inhibitors,research,lifescience,medical Such a suitable eukaryotic organism is yeast, as it fulfills all the requirements listed above [8,9]. One of the yeasts investigated best is the common bakers’ yeast, S. cerevisiae, for which complete genome, as well as detailed protein data, are available. Therefore, many studies have used this model organism for lipidomics studies. One of the major lipid categories of eukaryotic organisms are glycerophospholipids (GPs), which cover diverse biological roles

Inhibitors,research,lifescience,medical like cell compartmentalization, energy storage and multiple signaling functions. Consequently, they are the subject of many studies, because their biosynthesis and Apoptosis inhibitor metabolism is very similar to those of higher eukaryotes, with three main exceptions. Firstly, yeast phosphatidylserine (PS) is mainly synthesized by the CDP-DAG pathway and not by PS synthase from phosphatidylethanolamine (PE). Inhibitors,research,lifescience,medical Secondly, for phosphatidylcholine (PC) synthesis, an alternative route exists besides the Kennedy-Pathway (CDP-choline), which is the exclusive pathway in mammals. In yeast, the successive methylation of PE to mono-methyl-phosphatidylethanolamine (MMPE), di-methyl-phosphatidylethanolamine from (DMPE) and finally PC occurs, catalyzed by N-methyl-transferases [2,9]. Thirdly, the difference to mammals is the relatively low abundance of polyunsaturated fatty acids (PUFAs), or rather the complete absence of PUFAs like in S. cerevisiae. Numerous studies have been dedicated to understand the role of GPs in S. cerevisiae. It has been shown that the faultless biosynthesis and metabolism of particular GPs appear to be essential for cell vitality. For instance, mutations in the gene encoding the phosphatidylinositol (PI) synthase are lethal for the organism [6,9].