Negative Coupling as a Mechanism for Signal Propagation between C2 Domains of Synaptotagmin I
Negative Coupling as a Mechanism for Signal Propagation between C2 Domains of Synaptotagmin I
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DOI：
10.1371/journal.pone.0046748
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发表时间：
2012-10-05
期刊：
影响因子：
3.7
通讯作者：
Hinderliter, Anne
中科院分区：
文献类型：
--
作者：
Fealey, Michael E.;Gauer, Jacob W.;Hinderliter, Anne
突触结合蛋白I（Synaptotagmin I，Syt I）是一种位于囊泡中的蛋白质，其参与感知钙内流，从而触发神经递质的快速同步释放。Syt I如何利用其两个C2结构域整合信号和介导神经传递一直是一个有争议的研究领域，尽管流行的假说倾向于独立的功能。使用差示扫描量热法和荧光寿命光谱的热力学变性的方法，我们测试了一个替代的假设，其中两个域相互作用，合作传播结合信息。通过将两种方法全局拟合到展开的双态模型来确定C2A、C2B和C2AB构建体的稳定性自由能。通过比较C2A和C2B与C2AB的加和自由能，我们确定了Syt I的C2结构域之间的负耦合相互作用。这种相互作用不仅提供了传播信号的机械手段，而且还提供了协调神经传递分子事件的可能手段。
Synaptotagmin I (Syt I) is a vesicle-localized protein implicated in sensing the calcium influx that triggers fast synchronous release of neurotransmitter. How Syt I utilizes its two C2 domains to integrate signals and mediate neurotransmission has continued to be a controversial area of research, though prevalent hypotheses favor independent function. Using differential scanning calorimetry and fluorescence lifetime spectroscopy in a thermodynamic denaturation approach, we tested an alternative hypothesis in which both domains interact to cooperatively disseminate binding information. The free energy of stability was determined for C2A, C2B, and C2AB constructs by globally fitting both methods to a two-state model of unfolding. By comparing the additive free energies of C2A and C2B with C2AB, we identified a negative coupling interaction between the C2 domains of Syt I. This interaction not only provides a mechanistic means for propagating signals, but also a possible means for coordinating the molecular events of neurotransmission.