COPI buds 60-nm lipid droplets from reconstituted water-phospholipid-triacylglyceride interfaces, suggesting a tension clamp function
COPI buds 60-nm lipid droplets from reconstituted water-phospholipid-triacylglyceride interfaces, suggesting a tension clamp function
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DOI：
10.1073/pnas.1307685110
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发表时间：
2013-08-13
影响因子：
11.1
通讯作者：
Pincet, Frederic
中科院分区：
文献类型：
--
作者：
Thiam, Abdou Rachid;Antonny, Bruno;Pincet, Frederic
细胞器之间的细胞内运输是通过外壳蛋白复合物，外壳原体，从双层膜芽囊泡实现的。脂滴被单层保护，因此似乎不适合作为包衣剂的靶点。出乎意料的是，外壳蛋白复合物I（COPI）是某些蛋白质的脂滴靶向所必需的，这表明COPI和脂滴之间可能存在直接相互作用。在这里，我们发现COPI涂层组件可以从人工脂滴（LD）界面芽60纳米三酰甘油纳米液滴。这种出芽减少了装饰母体LD的单层的磷脂堆积。因此，疏水性三酰甘油分子变得更多地暴露于水性环境，增加LD表面张力。在体内，这种表面张力的增加可能引发脂滴与邻近蛋白质或膜的反应。它提供了一种与COPI形成转运囊泡根本不同的机制，可能是与COPI亚基耗竭相关的多种脂滴表型的原因。
Intracellular trafficking between organelles is achieved by coat protein complexes, coat protomers, that bud vesicles from bilayer membranes. Lipid droplets are protected by a monolayer and thus seem unsuitable targets for coatomers. Unexpectedly, coat protein complex I (COPI) is required for lipid droplet targeting of some proteins, suggesting a possible direct interaction between COPI and lipid droplets. Here, we find that COPI coat components can bud 60-nm triacylglycerol nanodroplets from artificial lipid droplet (LD) interfaces. This budding decreases phospholipid packing of the monolayer decorating the mother LD. As a result, hydrophobic triacylglycerol molecules become more exposed to the aqueous environment, increasing LD surface tension. In vivo, this surface tension increase may prime lipid droplets for reactions with neighboring proteins or membranes. It provides a mechanism fundamentally different from transport vesicle formation by COPI, likely responsible for the diverse lipid droplet phenotypes associated with depletion of COPI subunits.