Variant-specific dynamics of amyloid-b fibrils

阿尔茨海默病（AD）的特征之一是在阿尔茨海默病（AD）的神经系统中存在神经毒性淀粉样蛋白-β（Aβ）沉积物。 脑组织从低聚物到原纤维的所有A β物种都存在于动态平衡中，这被认为是 引发了一个病理性的级联反应，涉及其他易聚集的蛋白质。所谓的多态性， A β存在于多个水平，从A β的长度和分子修饰到形态学修饰。 同一分子结构内的差异，一般构象的差异和动力学内 一个单一的结构单元。翻译后修饰（PTMs）最近已被牵连， 散发性AD发作，因为它们被认为触发或加速野生型A β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略性 低聚物/原纤维混合物越来越多地涉及升高的细胞毒性。的长期目标 我们的研究是A β物种的内在柔性与现有结构，聚集， 和毒性研究，以确定构象集合在促进更多 有毒/侵略性状态。在确定了野生型A β的内在灵活性的主要特征之后， 纤维，以及我们的研究中几个PTM的无序N-末端结构域的关键灵活性特征。 以前的研究，我们建议检查哪些功能的构象合奏传播到 交叉播种的物种和其他动态变化相比，自我播种野生， A型血吸虫所提出的工作的目标是获得定量的现场具体特征的动态 Aβ1-40原纤维来源于几种策略性选择的系统的种子生长：a） 已发现N端区域Aβ1-40的PTM可增强纤颤动力学， 毒性;和B）在高浓度突触质膜存在下产生的种子 从大鼠脑组织（SV）的囊泡。后者至少可以部分地在同一范式内处理 假设SV表面和A β寡聚体/原纤维/原纤维混合物之间的相互作用 创造独特的构象集合，可以被认为是一个“修改”类似的， 对具有相对积极的聚集倾向的PTM进行播种行动。我们假设 的动力学特征从PTM或SV种子传播到野生型A β原纤维，并且这些 “保守”特征可能是与聚集倾向相关的最重要的特征， 交叉播种的侵略性。SV-A相互作用和PTM交叉播种的联合研究 印记可以促进我们对淀粉样纤维多态性与 聚集攻击性，最终揭示潜在相关的病理特征。我们 主要工具是静态氘固态核磁共振和计算模型的评估， 动力学和用于表征形态的透射电子显微镜。主要研究者 非常致力于培养来自不同背景的本科生，并建议培养 几个学生在样品制备，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.