The c2 domains of human synaptotagmin 1 have distinct mechanical properties.
The c2 domains of human synaptotagmin 1 have distinct mechanical properties.
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DOI：
10.1016/j.bpj.2008.10.025
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发表时间：
2009-02
影响因子：
3.4
通讯作者：
K. Fuson;Liang Ma;R B Sutton;A. Oberhauser
中科院分区：
文献类型：
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作者：
K. Fuson;Liang Ma;R B Sutton;A. Oberhauser
突触结合蛋白1（Synaptotagmin 1，Syt 1）是神经元中快速、同步囊泡融合的Ca+2受体。由于膜融合是一种固有的机械，力驱动的事件，Syt 1必须能够适应融合装置的能量学。Syt 1包含两个C2结构域（C2 A和C2B），它们在序列上同源，在结构上是三维的;然而，许多观察表明它们具有不同的生物化学和生物学特性。在这项研究中，我们分析了机械稳定性的C2 A和C2B域的人Syt 1使用单分子原子力显微镜。我们发现，拉伸Syt 1的C2 AB结构域导致两个不同的去折叠力峰。100 pN的较大力峰被鉴定为C2B，150 pN的第二个峰被鉴定为C2 A。此外，C2 A结构域的显著部分通过在C2B中未观察到的低力中间体展开。我们得出结论，这些领域有不同的机械性能。我们假设，一个相对较小的拉伸力可能足以变形的效应器结合区的C2 A域和调节的亲和力solubleN-乙基马来酰亚胺敏感因子（NSF）附着蛋白受体（SNARE），磷脂，和Ca+2。
Synaptotagmin 1 (Syt1) is the Ca+2receptor for fast, synchronous vesicle fusion in neurons. Because membrane fusion is an inherently mechanical, force-driven event, Syt1 must be able to adapt to the energetics of the fusion apparatus. Syt1 contains two C2 domains (C2A and C2B) that are homologous in sequence and three-dimensional in structure; yet, a number of observations have suggested that they have distinct biochemical and biological properties. In this study, we analyzed the mechanical stability of the C2A and C2B domains of human Syt1 using single-molecule atomic force microscopy. We found that stretching the C2AB domains of Syt1 resulted in two distinct unfolding force peaks. The larger force peak of ∼100 pN was identified as C2B and the second peak of ∼50 pN as C2A. Furthermore, a significant fraction of C2A domains unfolded through a low force intermediate that was not observed in C2B. We conclude that these domains have different mechanical properties. We hypothesize that a relatively small stretching force may be sufficient to deform the effector-binding regions of the C2A domain and modulate the affinity for solubleN-ethylmaleimide-sensitive factor (NSF) attachment protein receptors (SNAREs), phospholipids, and Ca+2.