钙离子依赖的突触融合蛋白-1从含有磷酸肌醇 4,5-二磷酸的 SNARE 复合物中的释放。
Ca-dependent release of synaptotagmin-1 from the SNARE complex on phosphatidylinositol 4,5-bisphosphate-containing membranes.
机构信息
Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, United States.
Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, United States.
出版信息
Elife. 2020 Aug 18;9:e57154. doi: 10.7554/eLife.57154.
The Ca sensor synaptotagmin-1 and the SNARE complex cooperate to trigger neurotransmitter release. Structural studies elucidated three distinct synaptotagmin-1-SNARE complex binding modes involving 'polybasic', 'primary' and 'tripartite' interfaces of synaptotagmin-1. We investigated these interactions using NMR and fluorescence spectroscopy. Synaptotagmin-1 binds to the SNARE complex through the polybasic and primary interfaces in solution. Ca-free synaptotagmin-1 binds to SNARE complexes anchored on PIP-containing nanodiscs. R398Q/R399Q and E295A/Y338W mutations at the primary interface, which strongly impair neurotransmitter release, disrupt and enhance synaptotagmin-1-SNARE complex binding, respectively. Ca induces tight binding of synaptotagmin-1 to PIP-containing nanodiscs, disrupting synaptotagmin-1-SNARE interactions. Specific effects of mutations in the polybasic region on Ca-dependent synaptotagmin-1-PIP-membrane interactions correlate with their effects on release. Our data suggest that synaptotagmin-1 binds to the SNARE complex through the primary interface and that Ca releases this interaction, inducing PIP/membrane binding and allowing cooperation between synaptotagmin-1 and the SNAREs in membrane fusion to trigger release.
钙离子传感器突触融合蛋白-1 和 SNARE 复合物共同作用触发神经递质释放。结构研究阐明了突触融合蛋白-1 与 SNARE 复合物的三种不同结合模式，涉及突触融合蛋白-1 的“多碱性”、“主要”和“三分体”界面。我们使用 NMR 和荧光光谱学研究了这些相互作用。在溶液中，突触融合蛋白-1 通过多碱性和主要界面与 SNARE 复合物结合。在含有 PIP 的纳米盘上锚定的 SNARE 复合物上，无 Ca 时的突触融合蛋白-1 结合。位于主要界面的 R398Q/R399Q 和 E295A/Y338W 突变强烈损害神经递质释放，分别破坏和增强突触融合蛋白-1-SNARE 复合物的结合。Ca 诱导突触融合蛋白-1 与含有 PIP 的纳米盘紧密结合，破坏突触融合蛋白-1-SNARE 相互作用。多碱性区突变对 Ca 依赖性突触融合蛋白-1-PIP-膜相互作用的特定影响与其对释放的影响相关。我们的数据表明，突触融合蛋白-1 通过主要界面与 SNARE 复合物结合，而 Ca 释放这种相互作用，诱导 PIP/膜结合，并允许突触融合蛋白-1 和 SNARE 之间在膜融合中合作，触发释放。
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