Structural and biochemical properties of lipid particles from the yeast Saccharomyces cerevisiae.
ABSTRACT The two most prominent neutral lipids of the yeast Saccharomyces cerevisiae, triacylglycerols (TAG) and steryl esters (SE), are synthesized by the two TAG synthases Dga1p and Lro1p and the two SE synthases Are1p and Are2p. In this study, we made use of a set of triple mutants with only one of these acyltransferases active to elucidate the contribution of each single enzyme to lipid particle (LP)/droplet formation. Depending on the remaining acyltransferases, LP from triple mutants contained only TAG or SE, respectively, with specific patterns of fatty acids and sterols. Biophysical investigations, however, revealed that individual neutral lipids strongly affected the internal structure of LP. SE form several ordered shells below the surface phospholipid monolayer of LP, whereas TAG are more or less randomly packed in the center of the LP. We propose that this structural arrangement of neutral lipids in LP may be important for their physiological role especially with respect to mobilization of TAG and SE reserves.
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ABSTRACT: Biosynthesis and storage of non-polar lipids such as triacylglycerols and steryl esters have gained much interest during the last decades because defects in these processes are related to severe human diseases. The baker's yeast Saccharomyces cerevisiae has become a valuable tool to study eukaryotic lipid metabolism because this single cell microorganism harbors many enzymes and pathways with counterparts in mammalian cells. In this article we will review aspects of triacylglycerol and steryl ester metabolism and turnover in the yeast which have been known for a long time, and combine them with new perceptions of non-polar lipid research. We will provide a detailed insight into the mechanisms of non-polar lipid synthesis, storage, mobilization and degradation in the yeast S. cerevisiae. The central role of lipid droplets in these processes will be addressed with emphasis on the prevailing view that this compartment is more than only a depot for triacylglycerols and steryl esters. Dynamic and interactive aspects of lipid droplets with other organelles will be discussed. Results obtained with S. cerevisiae will be complemented by recent investigations of non-polar lipid research with Yarrowia lipolytica and Pichia pastoris. Altogether, this review article provides a comprehensive view of non-polar lipid research in yeast. This article is protected by copyright. All rights reserved.FEMS microbiology reviews 03/2014; · 10.96 Impact Factor
Article: Yeast lipid metabolism at a glance.[Show abstract] [Hide abstract]
ABSTRACT: During the last decades, lipids have gained much attention due to their involvement in health and disease. Lipids are required for the formation of membranes and contribute to many different processes such as cell signaling, energy supply and cell death. Various organelles such as the endoplasmic reticulum, mitochondria, peroxisomes and lipid droplets are involved in lipid metabolism. The yeast Saccharomyces cerevisiae has become a reliable model organism to study biochemistry, molecular and cell biology of lipids. The availability of mutants bearing defects in lipid metabolic pathways and the ease of manipulation by culture conditions facilitated these investigations. Here, we summarize the current knowledge about lipid metabolism in yeast. We grouped this large topic into three sections dealing with (i) fatty acids; (ii) membrane lipids; and (iii) storage lipids. Fatty acids serve as building blocks for the synthesis of membrane lipids (phospholipids, sphingolipids) and storage lipids (triacylglycerols, steryl esters). Phospholipids, sterols and sphingolipids are essential components of cellular membranes. Recent investigations addressing lipid synthesis, degradation and storage as well as regulatory aspects are presented. The role of enzymes governing important steps of the different lipid metabolic pathways is described. Finally, the link between lipid metabolic and dynamic processes is discussed. This article is protected by copyright. All rights reserved.FEMS Yeast Research 02/2014; · 2.46 Impact Factor
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ABSTRACT: Lipid droplets (LDs) are ubiquitous dynamic organelles that store and supply lipids in all eukaryotic and some prokaryotic cells for energy metabolism, membrane synthesis, and production of essential lipid-derived molecules. Interest in the organelle's cell biology has exponentially increased over the last decade due to the link between LDs and prevalent human diseases and the discovery of new and unexpected functions of LDs. As a result, there has been significant recent progress toward understanding where and how LDs are formed, and the specific lipid pathways that coordinate LD biogenesis.The Journal of Cell Biology 03/2014; 204(5):635-46. · 10.82 Impact Factor