Integrative NMR and biophysical studies of fibrillar protein assemblies in health and disease

摘要 蛋白质自组装成结构化原纤维在生物学中发挥着功能和功能障碍的作用。我们是 研究两类原纤维形成蛋白：胶原蛋白，一种与胶原蛋白形成重要相互作用的原纤维 多种蛋白质和细胞外基质成分，以维持正常的细胞功能和 α-突触核蛋白 (αS)， 本质上无序的蛋白质，自组装成寡聚体和原纤维，与衰弱有关 突触核蛋白病，例如帕金森病。虽然在这两种情况下，原纤维通常被认为是刚性的， 相当惰性的实体，我们最近发现构象动力学深刻地影响了它们的原子- 纳米级的特性。尽管这些纤维蛋白很重要，但纤维蛋白的分子决定因素 蛋白质相互作用及其对健康和疾病的影响仍未得到解答。因此，总体目标 该提案的目的是了解分子运动和表面特性如何调节蛋白质相互作用 在不同的组装阶段（单体、低聚物、原纤维）、空间范围（原子到纳米尺度）和时间 制度（皮秒到小时）以促进正常的体内平衡或病理疾病状态。统一的 该提案的主题是我们正在开发原纤维所需的关键技术和协议 识别这些系统的构象可塑性和不同相互作用的表征。我们使用 集成溶液和固态核磁共振波谱、原子 力显微镜、冷冻电子显微镜、计算方法，并将这些与细胞实验联系起来。 我们正在解决胶原纤维如何识别其结合伙伴的问题（我们特别关注 整合素（一种参与血小板聚集的关键蛋白质），尽管事实上许多结合位点隐藏在 复杂的胶原纤维结构。除了健康原纤维的结构/功能之外，我们还将研究 GlyX 突变对遗传性结缔组织疾病如成骨不全症（脆性 骨疾病）并首次可视化这些缺陷如何影响原纤维的组装、结构和 功能。尽管这是一个非常不同的生物系统，但我们对 αS 提出了类似的原纤维相互作用问题：细胞与 细胞增殖和原纤维内源 αS 单体的模板接种增加了原纤维的数量 并且是疾病进展的主要因素之一。这种相互作用机制尚不清楚，我们 将首先从原子到纳米尺度表征淀粉样蛋白表面，然后进行研究 可视化单体与它们的相互作用。结果将揭示以下问题的性质和特殊性： 胶原蛋白和 αS 相互作用、疾病相关胶原蛋白突变的生物物理和生物学影响， 以及病理性细胞间传播和 αS 聚集体播种的机制。阐释小说 相互作用机制将有助于设计新的治疗策略来拯救受损的胶原蛋白 破坏性神经退行性疾病中的相互作用或病理性 αS 聚集。

Abstract Protein self-assembly into structured fibrils plays both functional and dysfunctional roles in biology. We are investigating two classes of fibril forming proteins: collagen, a fibril that forms essential interactions with numerous proteins and extracellular matrix components for proper cellular function and α-synuclein (αS), an intrinsically disordered protein that self-assembles into oligomers and fibrils that are associated with debilitating synucleinopathies, such as Parkinson’s Disease. While in both cases, fibrils are often thought of as rigid, rather inert, entities, we have recently discovered conformational dynamics that profoundly impact their atomic- to-nano scale properties. Despite the importance of these fibrillar proteins, the molecular determinants of fibril- protein interactions and their impact in health and disease remain unanswered. Thus, the overarching objective of this proposal is to understand how molecular motions and surface properties modulate protein interactions at different assembly stages (monomer, oligomer, fibril), spatial extent (atomic to nanoscale), and temporal regime (picosecond to hours) to promote normal homeostasis or pathological disease states. The unifying theme of this proposal is that we are developing the key techniques and protocols necessary for fibril characterization that recognize the conformational plasticity and diverse interactions of these systems. We use a multifaceted approach integrating solution and solid-state nuclear magnetic resonance spectroscopy, atomic force microscopy, cryo-electron microscopy, computational methods, and link these to cellular experimentation. We are addressing the question of how collagen fibrils recognize their binding partners (we focus in particular on integrin, a key protein involved in platelet aggregation) despite the fact that many binding sites are hidden in the complex collagen fibril architecture. Beyond structure/function in healthy fibrils, we will investigate the impact of GlyX mutations in hereditary connective tissue disease such as Osteogenesis Imperfecta (brittle bone disease) and visualize for the first time how these defects impact on fibril assembly, structure and function. Although a very different biological system, we raise similar fibril interaction questions for αS: cell-to- cell propagation and templated seeding of endogenous αS monomers by fibrils increases the number of fibrils and is one of the primary factors in disease progression. This interaction mechanism is not understood and we will investigate this by first characterizing amyloid surfaces from the atomic to the nano-scale and then visualizing the interactions of the monomers with them. Results will shed light on the nature and specificity of collagen and αS interactions, the biophysical and biological impact of disease-affiliated collagen mutations, and mechanisms of pathological cell-to-cell propagation and seeding of αS aggregates. Elucidating novel interaction mechanisms will aid in design of new therapeutic strategies to rescue compromised collagen interactions or pathological αS aggregation in devastating neurodegenerative disease.