Accessory proteins stabilize the acceptor complex for synaptobrevin, the 1:1 syntaxin/SNAP-25 complex
Accessory proteins stabilize the acceptor complex for synaptobrevin, the 1:1 syntaxin/SNAP-25 complex
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DOI：
10.1016/j.str.2007.12.010
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发表时间：
2008-02-01
期刊：
影响因子：
5.7
通讯作者：
Brunger, Axel T.
中科院分区：
文献类型：
--
作者：
Weninger, Keith;Bowen, Mark E.;Brunger, Axel T.
Syntaxin/SNAP-25相互作用先于三元SNARE复合物的组装，这对神经递质释放至关重要。这种二元配合物很难用散装方法表征，因为普遍存在2:1的死端物种。在这里，使用单分子荧光，我们发现1:1 syntaxin/SNAP-25二元配合物的结构是可变的，其状态在第二个时间尺度上发生变化。一种状态对应于一个平行的三螺旋束，而其他状态显示SNAP-25 SNARE结构域的一个解离。加入synaptobrevin抑制解离螺旋状态。值得注意的是，在添加复合蛋白、Munc13、Munc18或synaptotagmin后，观察到类似的效果。因此，1:1二元复合物是突触蛋白结合的动态受体，辅助蛋白稳定该受体。在细胞环境中，二元复合物被积极地维持在一种结构中，它可以快速地与突触蛋白相互作用，因此形成不太可能是神经递质释放的限制步骤。
Syntaxin/SNAP-25 interactions precede assembly of the ternary SNARE complex that is essential for neurotransmitter release. This binary complex has been difficult to characterize by bulk methods because of the prevalence of a 2:1 dead-end species. Here, using single-molecule fluorescence, we find the structure of the 1:1 syntaxin/SNAP-25 binary complex is variable, with states changing on the second timescale. One state corresponds to a parallel three-helix bundle, whereas other states show one of the SNAP-25 SNARE domains dissociated. Adding synaptobrevin suppresses the dissociated helix states. Remarkably, upon addition of complexin, Munc13, Munc18, or synaptotagmin, a similar effect is observed. Thus, the 1:1 binary complex is a dynamic acceptor for synaptobrevin binding, and accessory proteins stabilize this acceptor. In the cellular environment the binary complex is actively maintained in a configuration where it can rapidly interact with synaptobrevin, so formation is not likely a limiting step for neurotransmitter release.