Variant-specific dynamics of amyloid-b fibrils

阿尔茨海默病(AD)的特征之一是在脑组织中存在神经毒性淀粉样蛋白(Aβ，Aβ)沉积 脑组织。从低聚物到纤维的所有A物种都存在着动态平衡，这被认为是 触发病理性级联反应，牵连到其他易于聚集的蛋白质。所谓的多态 存在于多个水平上，从的长度和分子修饰到形态 同一分子结构内的差异，到内部的一般构象多样性和动力学 一个单一的结构单元。翻译后修饰(PTM)最近被认为与 散发性阿尔茨海默病的发病，因为它们被认为触发或加速了野生型A肽的纤颤 并增强其毒性。此外，膜-A相互作用和由此产生的侵袭性 低聚物/原纤维混合物越来越多地涉及到更高的细胞毒性。的长期目标是 我们的研究是物种的内在灵活性与现有的结构、聚集、 和毒理学研究，以确定构象集合在促进更多 有毒/好斗的状态。确立了野生型A内在灵活性的主要特征 纤维，以及几个PTM的无序N-末端结构域的关键灵活性特征 在以前的研究中，我们建议检查构象系综的哪些特征传播到 与自种野生物种相比，杂交种子物种和其他动态变化是什么？ A类。这项拟议工作的目标是获得特定地点的动力学定量特征 在Aβ中，1-40纤维起源于几个策略性选择的系统的种子生长：a)种子 N-末端区域Aβ1-40的PTM，已被发现增强纤颤动力学和 毒性；以及b)在高浓度突触质膜存在下产生的种子 大鼠脑组织中的囊泡(SV)。后者至少可以在相同的范例中得到部分治疗 作为PTMS，假设SV表面与A齐聚物/原纤维/纤维混合物之间的相互作用 创造独特的构象系综，可以被认为是其类似于 向具有相对激进的聚集倾向的PTM播种的行为。我们假设一个范围 的动态特征从PTMS或SV种子传播到野生型A原纤维，并且这些 “保守的”特征可能是最重要的与聚集倾向和 交叉播种的攻击性。SV-A相互作用与交叉播种的联合研究 印迹可以促进我们对淀粉样蛋白纤维多态和 聚集侵袭性，最终揭示了潜在的相关病理特征。我们的 主要工具是静态氚固体核磁共振和用于评估的计算模型 动力学，和透射电子显微镜的形貌表征。圆周率是 非常致力于培养不同背景的本科生，并建议培养 几名学生在样品制备、光谱学和建模方面。

One of the hallmarks of Alzheimer’s disease (AD) is the presence of neurotoxic amyloid-β (Aβ) deposits in brain tissue. All A species from oligomers to fibrils exist in a dynamic equilibrium, which is believed to trigger a pathological cascade implicating other aggregation-prone proteins. The so-called polymorphism of A exists at multiple levels, from the length and molecular modifications of A to the morphological differences within the same molecular structure, to general conformational diversities and dynamics within a single structural unit. The post-translational modifications (PTMs) have been recently implicated in sporadic AD onset, as they are thought to trigger or accelerate the fibrillation of the wild-type A peptide and enhance its toxicity. Further, membrane-A interactions and the resulting aggressive oligomeric/protofibrils mixtures are increasingly implicated in elevated cytotoxicities. The long-term goal of our research is the correlation of the intrinsic flexibility of A species with existing structural, aggregation, and toxicitiy studies in order to pinpoint the role of conformational ensembles in promoting more toxic/aggressive states. Having established the main features of the intrinsic flexibility of the wild-type A fibrils, as well as the key flexibility features of the disordered N-terminal domain of several PTMs in our previous studies, we propose to examine which features of conformational ensembles propagate into the cross-seeded species and what other dynamical alterations are seen compared with the self-seeded wild- type A. The goal of the proposed work is to obtain quantitative site-specific characterizations of dynamics in the Aβ1-40 fibrils originating from the seeded growth of several strategically chosen systems: a) seeds with PTMs of Aβ1-40 in the N-terminal region, which have been found to enhance fibrillation kinetics and toxicities; and b) seeds produced in the presence of high concentration of synaptic plasma membrane vesicles from rats’ brain tissues (SV). The latter can be at least partially treated within the same paradigm as PTMs, assuming that the interactions between the SV surface and A oligomer/protofibrils/fibrils mixtures create unique conformational ensembles that can be considered to be a “modification” analogous in its seeding actions to PTMs with relatively aggressive aggregation propensities. We hypothesize that a range of dynamical features propagate from the PTMs or SV seeds to the wild-type A fibrils and that these “conserved” features may be the most important for the correlations with aggregation propensities and cross-seeding aggressiveness. The joint investigation of the SV-A interactions and PTM cross-seeding imprint can advance our understanding of the relationship between the amyloid fibril polymorphism and aggregation aggressiveness, ultimately shedding light on potentially relevant pathological features. Our main tools are static deuterium solid-state NMR and computational modeling for the assessment of the dynamics, and transmission electron microscopy for characterization of the morphologies. The PI is extremely committed to training undergraduate students from diverse background and proposes to train several students in sample preparation, spectroscopy, and modeling aspects.