Rajakumari Sona, Grillitsch Karlheinz, Daum Günther
Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, A-8010 Graz, Austria.
Prog Lipid Res. 2008 May;47(3):157-71. doi: 10.1016/j.plipres.2008.01.001. Epub 2008 Jan 18.
In the yeast Saccharomyces cerevisiae as in other eukaryotic cells non-polar lipids form a reservoir of energy and building blocks for membrane lipid synthesis. The yeast non-polar lipids, triacylglycerol (TAG) and steryl ester (STE), are synthesized by enzymes with overlapping function. Recently, genes encoding these enzymes were identified and gene products were partially characterized. Once formed, TAG and STE are stored in so-called lipid particles/droplets. This compartment which is reminiscent of mammalian lipoproteins from the structural viewpoint is, however, not only a lipid depot but also an organelle actively contributing to lipid metabolism. Non-polar lipid degrading enzymes, TAG lipases and STE hydrolases, also occur in redundancy in the yeast. These proteins, which are components of the lipid particle surface membrane with the exception of one plasma membrane localized STE hydrolase, mobilize non-polar lipids upon requirement. In this review, we describe the coordinate pathways of non-polar lipid synthesis, storage and mobilization in yeast with special emphasis on the role of the different enzymes and organelles involved in these processes. Moreover, we will discuss non-polar lipid homeostasis and its newly discovered links to various cell biological processes in the yeast.
在酿酒酵母中，与其他真核细胞一样，非极性脂质构成了能量储备以及膜脂合成的原料库。酵母中的非极性脂质，即三酰甘油（TAG）和甾醇酯（STE），由功能重叠的酶合成。最近，编码这些酶的基因已被鉴定出来，并且对基因产物进行了部分表征。一旦形成，TAG和STE就会储存在所谓的脂质颗粒/液滴中。从结构角度来看，这个区室让人联想到哺乳动物的脂蛋白，但它不仅是一个脂质储存库，也是一个积极参与脂质代谢的细胞器。非极性脂质降解酶，即TAG脂肪酶和STE水解酶，在酵母中也存在冗余。这些蛋白质，除了一种定位于质膜的STE水解酶外，都是脂质颗粒表面膜的组成成分，在需要时动员非极性脂质。在这篇综述中，我们描述了酵母中非极性脂质合成、储存和动员的协调途径，特别强调了参与这些过程的不同酶和细胞器的作用。此外，我们将讨论非极性脂质稳态及其与酵母中各种细胞生物学过程新发现的联系。
