Zanetti Maria N, Bello Oscar D, Wang Jing, Coleman Jeff, Cai Yiying, Sindelar Charles V, Rothman James E, Krishnakumar Shyam S
Department of Cell Biology, Yale School of Medicine, New Haven, United States.
Department of Molecular Biophysics and Biochemistry, Yale School of Medicine, New Haven, United States.
Elife. 2016 Jul 19;5:e17262. doi: 10.7554/eLife.17262.
We recently reported that the C2AB portion of Synaptotagmin 1 (Syt1) could self-assemble into Ca(2+)-sensitive ring-like oligomers on membranes, which could potentially regulate neurotransmitter release. Here we report that analogous ring-like oligomers assemble from the C2AB domains of other Syt isoforms (Syt2, Syt7, Syt9) as well as related C2 domain containing protein, Doc2B and extended Synaptotagmins (E-Syts). Evidently, circular oligomerization is a general and conserved structural aspect of many C2 domain proteins, including Synaptotagmins. Further, using electron microscopy combined with targeted mutations, we show that under physiologically relevant conditions, both the Syt1 ring assembly and its rapid disruption by Ca(2+) involve the well-established functional surfaces on the C2B domain that are important for synaptic transmission. Our data suggests that ring formation may be triggered at an early step in synaptic vesicle docking and positions Syt1 to synchronize neurotransmitter release to Ca(2+) influx.
我们最近报道，突触结合蛋白1（Syt1）的C2AB部分可在膜上自组装成对Ca(2+)敏感的环状寡聚体，这可能潜在地调节神经递质释放。在此我们报道，类似的环状寡聚体由其他Syt亚型（Syt2、Syt7、Syt9）的C2AB结构域以及相关的含C2结构域蛋白Doc2B和延伸突触结合蛋白（E-Syts）组装而成。显然，环状寡聚化是许多C2结构域蛋白（包括突触结合蛋白）普遍且保守的结构特征。此外，通过结合电子显微镜和靶向突变，我们表明在生理相关条件下，Syt1环组装及其被Ca(2+)快速破坏都涉及C2B结构域上已确立的对突触传递很重要的功能表面。我们的数据表明，环形成可能在突触小泡对接的早期步骤被触发，并使Syt1定位以将神经递质释放与Ca(2+)内流同步。
