A mechanism for exocyst-mediated tethering via Arf6 and PIP5K1C driven phosphoinositide conversion
A mechanism for exocyst-mediated tethering via Arf6 and PIP5K1C driven phosphoinositide conversion
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通过 Arf6 和 PIP5K1C 驱动的磷酸肌醇转化进行外囊介导的束缚机制
DOI：
10.1101/2021.10.14.464363
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Maib H
中科院分区：
文献类型：
--
作者：
Maib H
极化转运是真核生物发育所必需的，受保守的分子机制调控。货物运送的后期步骤是由囊泡复合物介导的，它整合脂质和蛋白质成分，以系住囊泡，进行质膜融合。然而，这一过程的分子机制尚不明确。在这里，我们重建了功能性八聚体人囊，证明了全复合物聚结和生物化学稳定的亚复合物的基础。我们确定每个亚复合物独立结合磷脂酰肌醇4,5-二磷酸（PI(4,5)P2），这是最低限度的膜系结。通过重构和上皮细胞生物学实验，我们发现arf6介导的脂质激酶PIP5K1C的募集可以快速将磷脂酰肌醇4-磷酸（PI(4)P）转化为PI(4,5)P2，从而驱动外囊募集和膜系固。这些结果提供了胞囊介导系栓的分子机制，以及质膜附近晚期囊泡磷酸化肌苷信号的独特功能需求。
Polarized trafficking is necessary for the development of eukaryotes and is regulated by a conserved molecular machinery. Late steps of cargo delivery are mediated by the exocyst complex, which integrates lipid and protein components to tether vesicles for plasma membrane fusion. However, the molecular mechanisms of this process are poorly defined. Here, we reconstitute functional octameric human exocyst, demonstrating the basis for holocomplex coalescence and biochemically stable subcomplexes. We determine that each subcomplex independently binds to phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2), which is minimally sufficient for membrane tethering. Through reconstitution and epithelial cell biology experiments, we show that Arf6-mediated recruitment of the lipid kinase PIP5K1C rapidly converts phosphatidylinositol 4-phosphate (PI(4)P) to PI(4,5)P2, driving exocyst recruitment and membrane tethering. These results provide a molecular mechanism of exocyst-mediated tethering and a unique functional requirement for phosphoinositide signaling on late-stage vesicles in the vicinity of the plasma membrane.