Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
Science. 2012 Jun 22;336(6088):1581-4. doi: 10.1126/science.1221976. Epub 2012 May 31.
Cellular membrane fusion is thought to proceed through intermediates including docking of apposed lipid bilayers, merging of proximal leaflets to form a hemifusion diaphragm, and fusion pore opening. A membrane-bridging four-helix complex of soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) mediates fusion. However, how assembly of the SNARE complex generates docking and other fusion intermediates is unknown. Using a cell-free reaction, we identified intermediates visually and then arrested the SNARE fusion machinery when fusion was about to begin. Partial and directional assembly of SNAREs tightly docked bilayers, but efficient fusion and an extended form of hemifusion required assembly beyond the core complex to the membrane-connecting linkers. We propose that straining of lipids at the edges of an extended docking zone initiates fusion.
细胞融合被认为通过中间产物进行，包括对接相邻的脂质双层、融合近膜小叶形成半融合膈膜，以及融合孔的打开。一种可溶性 N-乙基马来酰亚胺敏感因子附着蛋白受体（SNARE）的膜桥接四螺旋复合物介导融合。然而，SNARE 复合物的组装如何产生对接和其他融合中间产物尚不清楚。我们使用无细胞反应在融合即将开始时可视化地鉴定中间产物，然后阻止 SNARE 融合机制。SNARE 的部分和定向组装使双层紧密对接，但有效的融合和半融合的扩展形式需要组装到核心复合物之外到连接膜的连接物。我们提出，在扩展对接区域的边缘处脂质的拉伸引发融合。
