Müllner Heidemarie, Daum Günther
Institut für Biochemie, Technische Universität Graz, Graz, Austria.
Acta Biochim Pol. 2004;51(2):323-47.
Since energy storage is a basic metabolic process, the synthesis of neutral lipids occurs in all kingdoms of life. The yeast, Saccharomyces cerevisiae, widely accepted as a model eukaryotic cell, contains two classes of neutral lipids, namely steryl esters and triacylglycerols. Triacylglycerols are synthesized through two pathways governed by the acyl-CoA diacylglycerol acyltransferase Dga1p and the phospholipid diacylglycerol acyltransferase Lro1p, respectively. Steryl esters are formed by the two steryl ester synthases Are1p and Are2p, two enzymes with overlapping function which also catalyze triacylglycerol formation, although to a minor extent. Storage of neutral lipids is tightly linked to the biogenesis of so called lipid particles. The role of this compartment in lipid homeostasis and its interplay with other organelles involved in neutral lipid dynamics, especially the endoplasmic reticulum and the plasma membrane, are subject of current investigations. In contrast to neutral lipid formation, mobilization of triacylglycerols and steryl esters in yeast are less characterized at the molecular level. Only recently, the triacylglycerol lipase Tgl3p was identified as the first yeast enzyme of this kind by function. Genes and gene products governing steryl ester mobilization still await identification. Besides biochemical properties of enzymes involved in yeast neutral lipid synthesis and degradation, regulatory aspects of these pathways and cell biological consequences of neutral lipid depletion will be discussed in this minireview.
由于能量储存是一个基本的代谢过程，中性脂质的合成发生在所有生命王国中。酵母，即酿酒酵母，被广泛认为是一种典型的真核细胞，它含有两类中性脂质，即甾醇酯和三酰甘油。三酰甘油通过分别由酰基辅酶A二酰甘油酰基转移酶Dga1p和磷脂二酰甘油酰基转移酶Lro1p控制的两条途径合成。甾醇酯由两种甾醇酯合成酶Are1p和Are2p形成，这两种酶功能重叠，也催化三酰甘油的形成，尽管程度较小。中性脂质脂质的储存与所谓脂质颗粒的生物发生紧密相关。这个区室在脂质稳态中的作用及其与参与中性脂质动态变化的其他细胞器，特别是内质网和质膜的相互作用，是当前研究的主题。与中性脂质形成相反，酵母中三酰甘油和甾醇酯的动员在分子水平上的特征较少。直到最近，三酰甘油脂肪酶Tgl3p才被功能鉴定为酵母中的第一种此类酶。控制甾醇酯动员的基因和基因产物仍有待鉴定。除了酵母中性脂质合成和降解相关酶的生化特性外，本综述还将讨论这些途径的调控方面以及中性脂质消耗的细胞生物学后果。
