Membrane fusion induced by neuronal SNAREs transits through hemifusion
Membrane fusion induced by neuronal SNAREs transits through hemifusion
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DOI：
10.1074/jbc.m506862200
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发表时间：
2005-08-26
影响因子：
4.8
通讯作者：
Shin, YK
中科院分区：
文献类型：
--
作者：
Lu, XB;Zhang, F;Shin, YK
突触传递需要神经递质通过与突触前质膜的膜融合从突触囊泡中有控制地释放出来。SNAREs是负责突触膜融合的蛋白质机制的核心成分。SNAREs驱动膜融合的机制被认为涉及半融合中间体，即两个双层膜的外层小叶结合而内部小叶保持完整的条件；然而，半灌注只被观察到作为终点而不是中间过程。在这里，我们研究了重组神经元SNAREs介导的脂质体膜融合动力学，使用荧光分析来监测总脂质混合和内小叶混合。我们的结果表明，半融合在融合反应的早期阶段占主导地位。随着时间的推移，半融合过渡到完全融合，表明半融合是一个真正的中间过程。我们还表明，通过调节SNARE蛋白的表面浓度，半融合中间体可以被捕获，可能作为非生产性结果。
Synaptic transmission requires the controlled release of neurotransmitter from synaptic vesicles by membrane fusion with the presynaptic plasma membrane. SNAREs are the core constituents of the protein machinery responsible for synaptic membrane fusion. The mechanism by which SNAREs drive membrane fusion is thought to involve a hemifusion intermediate, a condition in which the outer leaflets of two bilayers are combined and the inner leaflets remain intact; however, hemifusion has been observed only as an end point rather than as an intermediate. Here, we examined the kinetics of membrane fusion of liposomes mediated by recombinant neuronal SNAREs using fluorescence assays that monitor both total lipid mixing and inner leaflet mixing. Our results demonstrate that hemifusion is dominant at the early stage of the fusion reaction. Over time, hemifusion transitioned to complete fusion, showing that hemifusion is a true intermediate. We also show that hemifusion intermediates can be trapped, likely as unproductive outcomes, by modulating the surface concentration of the SNARE proteins.