Syndapin I and endophilin I bind overlapping proline-rich regions of dynamin I: role in synaptic vesicle endocytosis
Syndapin I and endophilin I bind overlapping proline-rich regions of dynamin I: role in synaptic vesicle endocytosis
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DOI：
10.1111/j.1471-4159.2007.04574.x
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发表时间：
2007-08-01
影响因子：
4.7
通讯作者：
Robinson, Phillip J.
中科院分区：
文献类型：
--
作者：
Anggono, Victor;Robinson, Phillip J.
Dynamin I 在突触囊泡内吞作用 (SVE) 过程中介导囊泡分裂。其富含脯氨酸的结构域 (PRID) 与可以使膜变形的蛋白质子集的 Src 同源 3 (SH3) 结构域结合。 Syndapin I、两性蛋白 I 和内亲素 I 是与 SVE 相关的主要伙伴。 Syndapin 结合受动力磷酸盒中 Ser-774 和 Ser778 处的磷酸化控制。我们现在通过肽竞争和定点诱变来定义联苯酚和亲环素结合位点。两者都结合动力蛋白 PRID 的相同区域，并且都在核心 PxxP 基序周围表现出不寻常的双向结合模式，这与采用 II 类结合模式的两性蛋白不同。 Enclophilin 与动力蛋白中序列 (778)SPTPQRRA PAVPPARPGSR(796) 中的串联 PxxP 基序结合，其中 SPTPQ 是突出序列。相反，syndapin 结合涉及 (772)RRSPTSSPTPQRRAPAVPPARRPGSR(796) 区域中的两个组件。它需要单个 PxxP 核心和非 PxxP N 端锚定延伸，桥接磷酸盒并可能有助于结合特异性和亲和力。 Syndapin 结合对该区域几乎任何地方的负电荷的引入都非常敏感，这解释了为什么它是一种高度调谐的磷传感器。无法结合联苯酚或内皮素的动力点突变体的过度表达会抑制培养神经元中的 SVE。由于重叠的结合位点，动力蛋白和联苯酚或内亲蛋白之间的相互作用是相互排斥的。因为 Syndapin 充当磷酸传感器，这支持了它在突触去极化诱导的 SVE 中的作用，这涉及动力去磷酸化。我们提出联苯肽和内亲素在 SVE 期间的不同阶段或在机械上不同类型的 SVE 中发挥作用。
Dynamin I mediates vesicle fission during synaptic vesicle endocytosis (SVE). Its proline-rich domain (PRID) binds the Src-homology 3 (SH3) domain of a subset of proteins that can deform membranes. Syndapin I, amphiphysin I, and endophilin I are its major partners implicated in SVE. Syndapin binding is controlled by phosphorylation at Ser-774 and Ser778 in the dynamin phospho-box. We now define syndapin and enclophilin-bincling sites by peptide competition and sitedirected mutagenesis. Both bound the same region of the dynamin PRID and both exhibited unusual bidirectional binding modes around core PxxP motifs, unlike amphiphysin which employed a class II binding mode. Enclophilin binds to tandem PxxP motifs in the sequence (778)SPTPQRRA PAVPPARPGSR(796) in dynamin, with SPTPQ being an overhang sequence. In contrast, syndapin binding involves two components in the region (772)RRSPTSSPTPQRRAPAVPPARPGSR(796). It required a single PxxP core and a non-PxxP N-terminally anchored extension which bridges the phosphobox and may contribute to binding specificity and affinity. Syndapin binding is exquisitely sensitive to the introduction of negative charges almost anywhere along this region, explaining why it is a highly tuned phospho-sensor. Overexpression of dynamin point mutants that fail to bind syndapin or endophilin inhibit SVE in cultured neurons. Due to overlapping binding sites the interactions between dynamin and syndapin or endophilin were mutually exclusive. Because syndapin acts as a phospho-sensor, this supports its role in depolarization-induced SVE at the synapse, which involves dynamin dephosphorylation. We propose syndapin and endophilin function either at different stages during SVE or in mechanistically distinct types of SVE.