Protein Biochemistry, Institute of Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany.
Department of Molecular Pharmacology and Cell Biology, Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany.
Structure. 2019 Jun 4;27(6):977-987.e5. doi: 10.1016/j.str.2019.03.020. Epub 2019 Apr 25.
The scaffolding protein intersectin 1 plays important roles in clathrin-mediated endocytosis and in the replenishment of release-ready synaptic vesicles (SV). Two splice variants of intersectin's SH3A domain are expressed in the brain, and association of the neuron-specific variant with synapsin I has been shown to enable sustained neurotransmission and to be regulated by an adjacent C-terminal motif. Here, we demonstrate that the ubiquitously expressed short SH3A variant of intersectin 1 interacts with an N-terminal intramolecular sequence that operates synergistically with the C-terminal motif. NMR spectroscopic investigations show that the five-amino acid insertion into the β strand 2 of the neuronal SH3A variant introduces conformational plasticity incompatible with binding of the N-terminal sequence. The difference in the autoregulatory mechanism of the domain's variants differentially affects its synaptic binding partners, thereby establishing alternative splicing in conjunction with autoinhibitory motif variation as a mechanism to regulate protein interaction networks.
衔接蛋白 1 作为支架蛋白，在网格蛋白介导的胞吞作用和释放准备就绪的突触小泡 (SV) 的补充中发挥重要作用。衔接蛋白的 SH3A 结构域有两种剪接变体在脑中表达，与神经元特异性变体的关联已被证明能够实现持续的神经递质传递，并受相邻的 C 末端基序调节。在这里，我们证明普遍表达的衔接蛋白 1 的短 SH3A 变体与 N 端分子内序列相互作用，该序列与 C 端基序协同作用。NMR 光谱研究表明，神经元 SH3A 变体β链 2 中的五个氨基酸插入会引入构象灵活性，从而无法与 N 端序列结合。该结构域变体的自动调节机制的差异会对其突触结合伴侣产生影响，从而通过与自动抑制基序变化相结合的替代剪接作为调节蛋白质相互作用网络的机制。
