不同途径对酿酒酵母线粒体膜磷脂酰乙醇胺和磷脂酰胆碱供应的贡献。

Contribution of different pathways to the supply of phosphatidylethanolamine and phosphatidylcholine to mitochondrial membranes of the yeast Saccharomyces cerevisiae.

作者信息

Bürgermeister Maria, Birner-Grünberger Ruth, Nebauer Ruth, Daum Günther

机构信息

Institut für Biochemie, Technische Universität Graz, Petersgasse 12/2, A-8010 Graz, Austria.

出版信息

Biochim Biophys Acta. 2004 Nov 8;1686(1-2):161-8. doi: 10.1016/j.bbalip.2004.09.007.

DOI:10.1016/j.bbalip.2004.09.007

Abstract

In the yeast, three biosynthetic pathways lead to the formation of phosphatidylethanolamine (PtdEtn): (i) decarboxylation of phosphatidylserine (PtdSer) by phosphatidylserine decarboxylase 1 (Psd1p) in mitochondria; (ii) decarboxylation of PtdSer by Psd2p in a Golgi/vacuolar compartment; and (iii) the CDP-ethanolamine (CDP-Etn) branch of the Kennedy pathway. The major phospholipid of the yeast, phosphatidylcholine (PtdCho), is formed either by methylation of PtdEtn or via the CDP-choline branch of the Kennedy pathway. To study the contribution of these pathways to the supply of PtdEtn and PtdCho to mitochondrial membranes, labeling experiments in vivo with [(3)H]serine and [(14)C]ethanolamine, or with [(3)H]serine and [(14)C]choline, respectively, and subsequent cell fractionation were performed with psd1Delta and psd2Delta mutants. As shown by comparison of the labeling patterns of the different strains, the major source of cellular and mitochondrial PtdEtn is Psd1p. PtdEtn formed by Psd2p or the CDP-Etn pathway, however, can be imported into mitochondria, although with moderate efficiency. In contrast to mitochondria, microsomal PtdEtn is mainly derived from the CDP-Etn pathway. PtdEtn formed by Psd2p is the preferred substrate for PtdCho synthesis. PtdCho derived from the different pathways appears to be supplied to subcellular membranes from a single PtdCho pool. Thus, the different pathways of PtdEtn biosynthesis play different roles in the assembly of PtdEtn into cellular membranes.

摘要

在酵母中，有三条生物合成途径可导致磷脂酰乙醇胺（PtdEtn）的形成：（i）线粒体中磷脂酰丝氨酸脱羧酶1（Psd1p）催化磷脂酰丝氨酸（PtdSer）脱羧；（ii）高尔基体/液泡区室中Psd2p催化PtdSer脱羧；以及（iii）肯尼迪途径的CDP-乙醇胺（CDP-Etn）分支。酵母的主要磷脂磷脂酰胆碱（PtdCho），可通过PtdEtn甲基化或经由肯尼迪途径的CDP-胆碱分支形成。为了研究这些途径对线粒体膜中PtdEtn和PtdCho供应的贡献，分别用[（3）H]丝氨酸和[（14）C]乙醇胺，或用[（3）H]丝氨酸和[（14）C]胆碱在体内进行标记实验，随后对psd1Δ和psd2Δ突变体进行细胞分级分离。通过比较不同菌株的标记模式表明，细胞和线粒体PtdEtn的主要来源是Psd1p。然而，由Psd2p或CDP-Etn途径形成的PtdEtn可以导入线粒体，尽管效率适中。与线粒体不同，微粒体PtdEtn主要来源于CDP-Etn途径。由Psd2p形成的PtdEtn是PtdCho合成的首选底物。来自不同途径的PtdCho似乎从单一的PtdCho池中供应到亚细胞膜。因此，PtdEtn生物合成的不同途径在将PtdEtn组装到细胞膜中发挥着不同的作用。