A phospholipid transfer function of ER-mitochondria encounter structure revealed in vitro.
A phospholipid transfer function of ER-mitochondria encounter structure revealed in vitro.
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DOI：
10.1038/srep30777
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发表时间：
2016-07-29
影响因子：
4.6
通讯作者：
Tamura Y
中科院分区：
文献类型：
--
作者：
Kojima R;Endo T;Tamura Y
由于磷脂主要在内质网（ER）和线粒体内膜中合成，细胞如何将特定的磷脂适当地分配到不同的细胞膜是维持细胞器特异性磷脂组合物的关键问题。虽然ER-线粒体相遇结构（ERMES）被提出来促进ER和线粒体之间的磷脂转移，但ERMES的这种作用仍然存在争议，有待实验证明。在这里，我们开发了一种新的体外检测系统与分离的酵母膜组分，以监测ER和线粒体之间的磷脂交换。通过该系统，我们发现ER和线粒体之间的磷脂转运依赖于膜的完整性，而不是能量来源，如ATP，GTP或跨线粒体内膜的膜电位。我们进一步发现，ERMES组分的缺乏损害了从ER到线粒体的磷脂酰丝氨酸转运，但不损害从线粒体到ER的磷脂酰乙醇胺转运。因此，这种体外测定系统提供了一个强大的工具来分析ER和线粒体之间的非囊泡磷脂转运。
As phospholipids are synthesized mainly in the endoplasmic reticulum (ER) and mitochondrial inner membranes, how cells properly distribute specific phospholipids to diverse cellular membranes is a crucial problem for maintenance of organelle-specific phospholipid compositions. Although the ER-mitochondria encounter structure (ERMES) was proposed to facilitate phospholipid transfer between the ER and mitochondria, such a role of ERMES is still controversial and awaits experimental demonstration. Here we developed a novel in vitro assay system with isolated yeast membrane fractions to monitor phospholipid exchange between the ER and mitochondria. With this system, we found that phospholipid transport between the ER and mitochondria relies on membrane intactness, but not energy sources such as ATP, GTP or the membrane potential across the mitochondrial inner membrane. We further found that lack of the ERMES component impairs the phosphatidylserine transport from the ER to mitochondria, but not the phosphatidylethanolamine transport from mitochondria to the ER. This in vitro assay system thus offers a powerful tool to analyze the non-vesicular phospholipid transport between the ER and mitochondria.