Defining the architecture and activation mechanisms of SynGAP

项目摘要 兴奋性突触在膜上表现出典型的蛋白质微室，称为 突触后密度(PSD)。PSD被丰富地组织成由以下组成的多蛋白质复合体 谷氨酸受体、支架、细胞骨架和信号效应器。企业重组的动态化 PSD信号复合体的高阶结构和组成是突触可塑性的基础， 学习和记忆。剖析PSD的相互作用和变构通讯机制 是了解突触可塑性的分子基础的先决条件。突触信号 对于主流的结构生物学方法来说，复合体是大的、高度动态的、有问题的目标。 该项目的总体目标是克服结构表征的挑战 PSD信号复合体通过应用蛋白质足迹、光谱、化学工具、 蛋白质组学方法探索生物相关环境中的蛋白质结构。这个项目 重点介绍了丰富的PSD--SynGAP的体系结构、激活机制和支架作用 GTP酶激活蛋白。SynGAP对大脑发育、长时程增强和空间 学习。重要的是，人类的SynGAP突变与自闭症谱系障碍有关， 精神分裂症和智力残疾。尽管它无处不在并发挥着中心信号作用，但该体系结构 SynGAP的信号机制在很大程度上仍不清楚。确定分子机制的研究 SynGAP信号对于理解SynGAP引起的大脑疾病的基础至关重要 功能障碍。混合结构生物学方法将被结合起来，以建立一个结构模型 多结构域全酶。这些方法独一无二地适用于表征动态蛋白质 溶液中的界面和构象变化。磷酸化诱导的构象变化 将被定义以确定激活机制。SynGAP显然调节相反的通路 通过对RAS和RAP的双重特异性来决定突触的强度。专用性转换 机制将通过绘制RAS和RAP相互作用的结构决定因素图来揭示。通过 剖析SynGAP功能的结构基础建议的研究将对以下方面做出重要贡献 正在进行的描述PSD分子结构的运动。解析SynGAP 信号复杂结构和机制将阐明SynGAP相关神经元疾病的基础 并推动未来治疗学的发展。

Project Summary Excitatory synapses exhibit characteristic proteinaceous microcompartments at the membrane known as the post-synaptic density (PSD). The PSD is richly organized into multi-protein complexes composed of glutamate receptors, scaffolds, cytoskeleton, and signaling effectors. The dynamic reorganizations of the higher-order architecture and composition of PSD signaling complexes underlies synaptic plasticity, learning, and memory. Dissecting the interactions and allosteric communication mechanisms of the PSD is a prerequisite for understanding the molecular underpinnings of synaptic plasticity. Synaptic signaling complexes are large and highly dynamic, problematic targets for mainstay structural biology approaches. The overarching goals of this project are to surmount the challenges of structural characterization of PSD signaling complexes by applying a battery of protein footprinting, spectroscopies, chemical tools, and proteomics approaches to probe protein structure in biologically relevant milieu. This project focuses on the architecture, activation mechanisms, and scaffolding roles of SynGAP, an abundant PSD GTPase-activating protein. SynGAP is critical to brain development, long-term potentiation, and spatial learning. Importantly, SynGAP mutations in humans are associated with autism spectrum disorders, schizophrenia, and intellectual disability. Despite its ubiquity and central signaling role, the architecture and signaling mechanisms of SynGAP remain largely unknown. Defining the molecular mechanisms of SynGAP signaling is critical for understanding the basis of brain disorders caused by SynGAP dysfunction. Hybrid structural biology approaches will be integrated to build a structural model of the multi-domain holoenzyme. These approaches are uniquely amenable to characterizing dynamic protein interfaces and conformational changes in solution. Phosphorylation-induced conformational changes will be defined to determine activation mechanisms. SynGAP apparently regulates opposing pathways dictating synaptic strength via dual specificity toward both Ras and Rap. Specificity switching mechanisms will be revealed by mapping structural determinants of Ras and Rap interactions. By dissecting the structural basis for SynGAP function the proposed research will be a vital contribution to the ongoing movement to characterize the molecular architecture of the PSD. Resolving SynGAP signaling complex structure and mechanisms will clarify the basis of SynGAP-linked neuronal disorders and spur the development of future therapeutics.