Centre National de la Recherche Scientifique and Université Paris Descartes, Unité Mixte de Recherche 8192, Institut de Biologie Physico-Chimique, 75005 Paris, France.
Proc Natl Acad Sci U S A. 2010 Feb 23;107(8):3517-21. doi: 10.1073/pnas.0914723107. Epub 2010 Feb 2.
Almost all known intracellular fusion reactions are driven by formation of trans-SNARE complexes through pairing of vesicle-associated v-SNAREs with complementary t-SNAREs on target membranes. However, the number of SNARE complexes required for fusion is unknown, and there is controversy about whether additional proteins are required to explain the fast fusion which can occur in cells. Here we show that single vesicles containing the synaptic/exocytic v-SNAREs VAMP/synaptobrevin fuse rapidly with planar, supported bilayers containing the synaptic/exocytic t-SNAREs syntaxin-SNAP25. Fusion rates decreased dramatically when the number of externally oriented v-SNAREs per vesicle was reduced below 5-10, directly establishing this as the minimum number required for rapid fusion. Docking-to-fusion delay time distributions were consistent with a requirement that 5-11 t-SNAREs be recruited to achieve fusion, closely matching the v-SNARE requirement.
几乎所有已知的细胞内融合反应都是通过形成跨 SNARE 复合物来驱动的，该复合物通过将囊泡相关的 v-SNARE 与靶膜上互补的 t-SNARE 配对来实现。然而，融合所需的 SNARE 复合物的数量是未知的，并且对于是否需要额外的蛋白质来解释可以在细胞中发生的快速融合存在争议。在这里，我们表明含有突触/胞吐 v-SNARE 的单个囊泡 VAMP/synaptobrevin 与含有突触/胞吐 t-SNARE 的平面支撑双层迅速融合 syntaxin-SNAP25。当每个囊泡上朝向外部的 v-SNARE 的数量减少到 5-10 个以下时，融合速率会急剧下降，这直接确定了这是快速融合所需的最小数量。对接-融合延迟时间分布与 5-11 个 t-SNARE 被招募以实现融合的要求一致，与 v-SNARE 的要求非常匹配。
