Phosphatidylinositol 3,5-bisphosphate regulates the transition between trans -SNARE complex formation and vacuole membrane fusion
Phosphatidylinositol 3,5-bisphosphate regulates the transition between trans -SNARE complex formation and vacuole membrane fusion
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磷脂酰肌醇 3,5-二磷酸调节反式-SNARE 复合物形成和液泡膜融合之间的转变
DOI：
10.1091/mbc.e18-08-0505
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发表时间：
2019
影响因子：
3.3
通讯作者：
Brennwald, Patrick J.
中科院分区：
文献类型：
--
作者：
Miner, Gregory E.;Sullivan, Katherine D.;Guo, Annie;Jones, Brandon C.;Hurst, Logan R.;Ellis, Ez C.;Starr, Matthew L.;Fratti, Rutilio A.;Brennwald, Patrick J.
磷脂酰肌醇(PI)调节多种细胞功能，包括膜融合，例如酵母液泡，它在融合的不同阶段使用不同的PI。鉴于此，磷脂酰肌醇3，5-二磷酸(PI(3，5)P2)对液泡融合的影响尚不清楚。PI(3，5)P_2是由PI3P 5-激酶FAB1合成的，它与Trp钙通道Yvc1相互作用，是高渗休克时空泡分裂的调节因子。在这里，我们证明了外源添加的二辛酰基(C8)PI(3，5)P取消了同型液泡融合。这种影响与Yvc1无关，因为融合同样受到vc1Δ空泡的影响。因此，C8-PI(3，5)P2on的融合和裂变通过不同的机制发挥作用。进一步的测试表明，C8-PI(3，5)P抑制了反式SNAR配对后的液泡融合。虽然没有影响SNARE复合体的形成，但我们发现C8-PI(3，5)P阻止了小叶外膜的脂质混合。由Fab1T2250A高活性激酶突变体过量生产的内源性PI(3，5)P也抑制了脂质混合阶段，支持了PI(3，5)P在高水平存在时抑制融合的模型。综上所述，本工作确定了PI(3，5)P作为空泡融合调节因子的新功能。此外，它还表明，这种类脂在分裂和融合之间起着分子开关的作用。
Phosphoinositides (PIs) regulate a myriad of cellular functions including membrane fusion, as exemplified by the yeast vacuole, which uses various PIs at different stages of fusion. In light of this, the effect of phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2) on vacuole fusion remains unknown. PI(3,5)P2is made by the PI3P 5-kinase Fab1 and has been characterized as a regulator of vacuole fission during hyperosmotic shock, where it interacts with the TRP Ca2+channel Yvc1. Here we demonstrate that exogenously added dioctanoyl (C8) PI(3,5)P2abolishes homotypic vacuole fusion. This effect was not linked to Yvc1, as fusion was equally affected usingyvc1Δ vacuoles. Thus, the effects of C8-PI(3,5)P2on fusion and fission operate through distinct mechanisms. Further testing showed that C8-PI(3,5)P2inhibited vacuole fusion aftertrans-SNARE pairing. Although SNARE complex formation was unaffected, we found that C8-PI(3,5)P2blocked outer leaflet lipid mixing. Overproduction of endogenous PI(3,5)P2by thefab1T2250Ahyperactive kinase mutant also inhibited the lipid mixing stage, bolstering the model in which PI(3,5)P2inhibits fusion when present at elevated levels. Taken together, this work identifies a novel function for PI(3,5)P2as a regulator of vacuolar fusion. Moreover, it suggests that this lipid acts as a molecular switch between fission and fusion.