Structure and Function of Alpha-Synuclein

描述（由申请人提供）：蛋白质α-突触核蛋白（aS）与家族性和散发性帕金森病（PD）的病因有关。aS的正常功能与其病理性聚集之间的相互作用知之甚少，但膜结合形式的aS被认为介导其生理功能，而聚集形式被认为介导蛋白质的毒性。在结构上，aS具有高度延展性，当在溶液中游离时采用高度无序的构象集合，当与磷脂膜结合时采用高度螺旋结构，并且当聚集成淀粉样蛋白原纤维时采用富含b-片层的构象。防止aS聚集成淀粉样纤维或潜在毒性的寡聚物物质是治疗PD的有希望的策略。本研究的总体目标是详细了解突触核蛋白的结构特性和转换如何调节突触核蛋白的功能和毒性，并确定特定的AS构象状态，以促进设计具有潜在治疗价值的突触核蛋白相互作用试剂。目前的建议旨在填补我们对aS结构的理解中新出现的空白，这些空白是由以下因素造成的：a）发现新的PD连锁的aS突变E46 K; B）发现膜结合的aS可以采用两种不同的拓扑结构，延伸的螺旋和断裂的螺旋，以及关于这两种构象如何影响突触核蛋白功能的假设的形成; c）发现被认为调节突触核蛋白功能的新的aS相互作用伙伴。为了填补这些空白，并解决新出现的假设，我们制定了以下具体目标：1。确定最近发现的PD连锁突变E46 K对游离和膜结合形式的aS结构的影响。2.以高分辨率阐明膜结合的aS的延伸螺旋结构。3.为了测试假设，即aS可以介导不同组成的拓扑结构不同的膜之间的相互作用，使用其先前阐明的断裂螺旋结构。4.确定AARP 16/19结合对膜相关aS结构的影响。这些目标的动机是有机会澄清aS序列变异如何影响蛋白质的结构和聚集，以及我们相信，单体膜结合的构象的aS，这是更高度有序的，可能更适合于形成特定的相互作用与潜在的治疗。这项工作将推进我们对aS结构、功能和聚集的理解，并将为未来设计和鉴定能够稳定单体aS并防止其低聚和聚集的试剂提供结构基础。此外，所获得的结果可能对解决其他年龄相关运动障碍和痴呆中蛋白质聚集的策略具有普遍意义。 公共卫生相关性：蛋白质α-突触核蛋白被认为在帕金森病的病因学中起重要作用。该提案旨在提高我们对这种蛋白质特定结构状态的理解，长期目标是促进我们在体内控制蛋白质结构转变的能力。预期这种能力允许开发用于治疗帕金森病的新治疗策略，帕金森病是第二常见的神经退行性疾病，这是一个对公共卫生具有明确和重大意义的目标。

DESCRIPTION (provided by applicant): The protein alpha-synuclein (aS) is implicated in the etiology of both familial and sporadic Parkinson's disease (PD). The interplay between the normal function of aS and its pathological aggregation is poorly understood, but membrane-bound forms of aS are thought to mediate its physiological function, while aggregated forms are thought to mediate the toxicity of the protein. Structurally, aS is highly malleable, adopting a highly disordered conformational ensemble when free in solution, highly helical structures when bound to phospholipids membranes and b-sheet rich conformations when aggregated into amyloid fibrils. Preventing the aggregation of aS into amyloid fibrils or potentially toxic oligomeric species is a promising strategy for the treatment of PD. The overarching goal of this research is to achieve a detailed understanding of how synuclein structural properties and transitions modulate synuclein function and toxicity and to identify specific conformational states of aS that could facilitate the design of synuclein-interacting reagents with potential therapeutic value. The current proposal is aimed at filling a newly emerged gaps in our understanding of aS structure that were created by a) the discovery of a new PD-linked aS mutation, E46K; b) the discovery that membrane-bound aS can adopt two different topologies, an extended helix and a broken helix, and the formulation of a hypothesis regarding how these two conformations may influence synuclein function; c) the discovery of new aS interaction partners thought to modulate synuclein function. To fill these gaps and to address emerging hypotheses we have developed the following specific aims: 1. To determine the effects of the most recently discovered PD-linked mutation, E46K, on structure in the free and membrane-bound forms of aS. 2. To elucidate at high resolution the extended-helix structure of membrane-bound aS. 3. To test the hypothesis that aS can mediate interactions between topologically distinct membranes of different compositions using its previously elucidated broken-helix structure. 4. To determine the effects of AARP16/19 binding on the structure of membrane-associated aS. These aims are motivated by the opportunity to clarify how aS sequence variations influence the structure and aggregation of the protein, and by our belief that monomeric membrane-bound conformations of aS, which are more highly ordered, may be better suited to form specific interactions with potential therapeutics. This work will advance our understanding of aS structure, function, and aggregation and will provide a structural basis for the future design and identification of reagents that can stabilize monomeric aS and prevent its oligomerization and aggregation. Furthermore, the results obtained may have general implications for strategies to address protein aggregation in other age-related motor disorders and dementias. PUBLIC HEALTH RELEVANCE: The protein alpha-synuclein is thought to play an important role in the etiology of Parkinson's disease. This proposal aims to improve our understanding of specific structural states of this protein, with the long-term goal of facilitating our ability to control the structural transitions of the protein in vivo. This ability is expected allow for the development of novel therapeutic strategies for the treatment of Parkinson's disease, the second most common neurodegenerative disorder, a goal with clear and significant implications for public health.