Department of Genetics, The University of Melbourne, Parkville, Victoria, Australia.
PLoS One. 2012;7(6):e38822. doi: 10.1371/journal.pone.0038822. Epub 2012 Jun 12.
The dicistronic Drosophila stoned gene is involved in exocytosis and/or endocytosis of synaptic vesicles. Mutations in either stonedA or stonedB cause a severe disruption of neurotransmission in fruit flies. Previous studies have shown that the coiled-coil domain of the Stoned-A and the µ-homology domain of the Stoned-B protein can interact with the C2B domain of Synaptotagmin-1. However, very little is known about the mechanism of interaction between the Stoned proteins and the C2B domain of Synaptotagmin-1. Here we report that these interactions are increased in the presence of Ca(2+). The Ca(2+)-dependent interaction between the µ-homology domain of Stoned-B and C2B domain of Synaptotagmin-1 is affected by phospholipids. The C-terminal region of the C2B domain, including the tryptophan-containing motif, and the Ca(2+) binding loop region that modulate the Ca(2+)-dependent oligomerization, regulates the binding of the Stoned-A and Stoned-B proteins to the C2B domain. Stoned-B, but not Stoned-A, interacts with the Ca(2+)-binding loop region of C2B domain. The results indicate that Ca(2+)-induced self-association of the C2B domain regulates the binding of both Stoned-A and Stoned-B proteins to Synaptotagmin-1. The Stoned proteins may regulate sustainable neurotransmission in vivo by binding to Ca(2+)-bound Synaptotagmin-1 associated synaptic vesicles.
双顺反子果蝇 stoned 基因参与突触囊泡的胞吐和/或胞吞作用。stonedA 或 stonedB 的突变会导致果蝇的神经递质传递严重中断。先前的研究表明，Stoned-A 的卷曲螺旋结构域和 Stoned-B 蛋白的 µ-同源结构域可以与突触融合蛋白 1 的 C2B 结构域相互作用。然而，关于 Stoned 蛋白与突触融合蛋白 1 的 C2B 结构域之间相互作用的机制知之甚少。在这里，我们报告说，这些相互作用在存在 Ca(2+)时会增加。µ-同源结构域的 Ca(2+)依赖性相互作用 Stoned-B 和 C2B 结构域的 Synaptotagmin-1 受磷脂影响。C2B 结构域的 C 端区域，包括含色氨酸的基序和调节 Ca(2+)-依赖性寡聚化的 Ca(2+)结合环区域，调节 Stoned-A 和 Stoned-B 蛋白与 C2B 结构域的结合。Stoned-B 而不是 Stoned-A 与 C2B 结构域的 Ca(2+)结合环区域相互作用。结果表明，C2B 结构域的 Ca(2+)诱导的自组装调节 Stoned-A 和 Stoned-B 蛋白与突触融合蛋白 1 的结合。通过与结合 Ca(2+)的突触融合蛋白 1 相关的突触囊泡结合，Stoned 蛋白可能调节体内可持续的神经递质传递。
