Amyloid-motif-dependent tau self-assembly is modulated by isoform sequence context

The microtubule-associated protein tau is implicated in neurodegenerative diseases characterized by amyloid formation. Mutations associated with frontotemporal dementia increase tau aggregation propensity and disrupt its endogenous microtubule-binding activity. However, the structural relationship between aggregation propensity and biological activity remains unclear. We employed a multi-disciplinary approach, including computational modeling, NMR, cross-linking mass spectrometry, and cell models to engineer tau sequences that modulate its structural ensemble. Our findings show that substitutions near the conserved 'PGGG' β-turn motif informed by tau isoform context reduce tau aggregation in vitro and cells and can even counteract aggregation promoting disease-associated proline-to-serine mutations. Engineered tau sequences maintain microtubule binding and explain why 3R isoforms exhibit reduced pathogenesis compared to 4R. We propose a simple mechanism to reduce the formation of pathogenic species while preserving biological function, thus offering insights for therapeutic strategies aimed at reducing tau protein misfolding in neurodegenerative diseases.

Description of Source Data and Supplementary Data: All MD, NMR (peptide and tauRD), ThT, XL-MS, MT stabilization, MT:tau modeling, and cell-based aggregation data are available in the Source_Data directory as Source Data 1, Source Data 2, Source Data 3 and 4, Source Data 5, Source Data 6, Source Data 7, and Source Data 8, respectively. Supplementary Data for raw MD trajectory files, structure files for MSM modeling and validation file, and tau:MT modeling are available as "Supplementary_Data_MD_Trajectories_Structures", "Supplementary_Data_MSM_models_Structures" and "Supplementary_Data_MT-tau_complex_models", respectively."

微管相关蛋白tau（microtubule-associated protein tau）与以淀粉样蛋白聚集为特征的神经退行性疾病密切相关。与额颞叶痴呆相关的突变会增强tau的聚集倾向，并破坏其内源的微管结合活性。然而，聚集倾向与生物学活性之间的结构关联仍不明确。本研究采用多学科研究手段，包括计算建模、核磁共振（NMR）、交联质谱（cross-linking mass spectrometry）及细胞模型，对tau序列进行工程化改造以调控其结构集合体。研究结果显示，结合tau亚型的上下文信息，在保守的“PGGG”β转角基序附近进行氨基酸取代，可在体外与细胞内降低tau的聚集水平，甚至可抵消疾病相关的脯氨酸向丝氨酸突变所带来的促聚集效应。经工程改造的tau序列仍可维持微管结合能力，这也解释了为何3R亚型的致病力相较于4R亚型更低。我们提出了一种简单的机制，可在保留tau生物学功能的前提下减少致病聚集体的形成，从而为针对神经退行性疾病中tau蛋白错误折叠的治疗策略提供了新的研究思路。

源数据与补充数据说明：所有分子动力学（MD）、核磁共振（含肽段与tau微管结合结构域（tauRD））、硫黄素T（ThT）、交联质谱、微管稳定实验、微管-tau建模及基于细胞的聚集实验数据，分别以源数据1、源数据2、源数据3、源数据4、源数据5、源数据6、源数据7和源数据8的形式存储于Source_Data目录中。原始分子动力学轨迹文件、马尔可夫状态模型（MSM）建模与验证所用的结构文件，以及tau-微管建模相关数据，分别以"Supplementary_Data_MD_Trajectories_Structures"、"Supplementary_Data_MSM_models_Structures"和"Supplementary_Data_MT-tau_complex_models"的名称作为补充数据提供。