Chemical approaches to selectively target beta-rich amyloids

项目摘要 蛋白质之间的相互作用受多肽二级结构之间的识别事件(a- 螺旋、b-折叠、环)，这些反过来又为开发选择性化学探针提供设计线索。 然而，从周围三级结构的上下文中去除有序的多肽结构域会损害 折叠和构象稳定性。B-链/片层相互作用的模仿和破坏仍然是相当大的 挑战。这在很大程度上是由于短肽序列固有的灵活性，即b-链的倾向。 要聚合，以及大表面积和多种模式的b-Sheet包装。早期的齐聚反应 几种淀粉样蛋白涉及到平行的b-折叠结构的构象重组，随后 超分子组装成有毒的纤维。最近使用患者提取液的原子级结构数据 揭示了神经毒性淀粉样蛋白可能具有独特的结构多态或菌株的特征，这取决于 关于这种疾病的。尽管需要淀粉样蛋白和菌株的特异性配体，但富含b的淀粉样蛋白组合代表 特别具有挑战性的目标。我们最近建立了肽骨架N-氨化作为一种微妙的 非常有效的b-链/片材稳定化方法。构象的和非聚集的 N-氨基多肽(NAP)的特性使其特别适合于限制片状纤维的生长 同时保持面部填充和侧链交错，对淀粉样蛋白识别非常重要。在这里，我们将 进一步开发各种b-片状折叠的可溶模拟物以破坏序列中的淀粉样聚集物和 特定于菌株的方式。作为概念验证，我们将针对tau纤维的组装和细胞传输 这是许多散发性和遗传性神经退行性疾病的特征。我们最重要的假设 多肽N-氨化的结构特征将使选择性靶向配体的发展成为可能 富含B的淀粉样蛋白折叠。在目标1中，我们将扩大NAP修饰的用途，以追求超稳定的b-链 和基于平行b-折叠大环的淀粉样蛋白模拟。一个基于NAP的tau模仿库将是 在AIM 2中合成。这些化合物将被评估它们阻断聚集和细胞的能力 重组tau纤维以及从AD患者中提取的tau纤维的传播。在目标3中，我们将合成一个 一系列抗聚集的NAP大循环，模拟病理性tau中观察到的交叉b堆积 菌株。将评估它们的能力，以特定地抑制由来自 广告和CBD大脑。我们预计，从这项研究中出现的配体将使对 Tau传播的致病株模型。更广泛地说，这些研究将对 B-折叠和淀粉样蛋白组件的其他选择性干扰物的设计，这些组件天生就很难靶向。

PROJECT ABSTRACT Protein-protein interactions are governed by recognition events between peptide secondary structures (a- helices, b-sheets, loops), which in turn provide design cues for the development of selective chemical probes. However, removal of ordered peptide domains from the context of the surrounding tertiary structure compromises folding and conformational stability. Mimicry and disruption of b-strand/sheet interactions remains a considerable challenge. This is largely due to the inherent flexibility of short peptide sequences, the propensity for b-strands to aggregate, and the large surface areas and diverse modes of b-sheet packing. The early oligomerization of several amyloidogenic proteins involves conformational reorganization into parallel b-sheet structures, followed supramolecular assembly into toxic fibrils. Recent atomic-level structural data using patient-derived extracts has revealed that neurotoxic amyloids may be characterized by unique structural polymorphs, or ‘strains’, depending on the disease. Despite the need for amyloid- and strain-specific ligands, b-rich amyloid assemblies represent particularly challenging targets. We recently established peptide backbone N-amination as a subtle yet remarkably effective approach to b-strand/sheet stabilization. The conformational and non-aggregating characteristics of N-amino peptides (NAPs) render them uniquely suited for capping the growth of sheet fibrils while maintaining the facial packing and sidechain interdigitation important for amyloid recognition. Here, we will further develop soluble mimics of diverse b-sheet-like folds to disrupt amyloid aggregation in a sequence and strain-specific manner. As a proof-of-concept, we will target the assembly and cellular transmission of tau fibrils that characterize numerous sporadic and hereditary neurodegenerative disorders. Our overarching hypothesis is that the structural features of peptide N-amination will enable the development of ligands that selectively target b-rich amyloid folds. In Aim 1 we will expand the utility of NAP modification in pursuit of hyperstable b-strands and amyloid mimics based on parallel b-sheet macrocycles. A library of NAP-based tau mimics will be synthesized in Aim 2. These compounds will be evaluated for their ability to block aggregation and cellular transmission of recombinant tau fibrils as well those extracted from AD patients. In Aim 3, we will synthesize a series of aggregation-resistant NAP macrocycles that mimic the cross-b packing observed in pathogenic tau strains. These will be evaluated for their capacity to specifically inhibit cellular seeding by tau fibrils derived from AD and CBD brains. We anticipate that ligands emerging from this study will enable a robust examination of the the pathogenic strain model of tau transmission. More broadly, these studies will have a significant impact on the design of other selective disruptors of b-sheet and amyloid assemblies that are inherently difficult to target.