Domain-specific modulatory effects of phosphomimetic substitutions on liquid-liquid phase separation of tau protein.
Domain-specific modulatory effects of phosphomimetic substitutions on liquid-liquid phase separation of tau protein.
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DOI：
10.1016/j.jbc.2023.104722
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发表时间：
2023-06
影响因子：
4.8
通讯作者：
Surewicz, Witold K
中科院分区：
文献类型：
--
作者：
Boyko, Solomiia;Surewicz, Witold K
tau蛋白聚集是阿尔茨海默病和其他神经退行性疾病的主要致病事件之一。最近的报道表明，tau可以凝结成液滴，并经历时间依赖性转变为固体状态，这表明液体冷凝物可能是tau病理聚集的途径之一。虽然过度磷酸化是从阿尔茨海默病和其他tau疾病患者的大脑中分离出的tau的一个关键特征，但磷酸化在tau液-液相分离（LLPS）中的机制作用仍未被探索。为了弥补这一差距，我们进行了系统的研究，通过在蛋白质的不同区域引入带负电荷的Asp/Glu残基取代Ser/Thr残基。我们的数据表明，增加全长tau （tau441）电荷分布极化的磷酸化模式促进了蛋白质LLPS，而减少电荷极化的磷酸化模式则具有相反的效果。总的来说，这项研究进一步支持了tau LLPS是由相反带电域之间的分子间静电相互作用驱动的这一观点。我们还表明，具有低LLPS内在倾向的拟磷tau变体可以有效地招募到具有高LLPS倾向的变体形成的液滴中。此外，目前的数据表明，拟磷取代对tau液滴的时间依赖性材料特性有重大影响，通常会减缓其老化。后一种效应对于重复结构域内具有取代的tau变异最为显著，这与该变异的纤颤率降低有关。
Aggregation of tau is one of the major pathogenic events in Alzheimer’s disease and several other neurodegenerative disorders. Recent reports demonstrated that tau can condense into liquid droplets that undergo time-dependent transition to a solid-like state, suggesting that liquid condensates may be on the pathway to pathological aggregation of tau. While hyperphosphorylation is a key feature of tau isolated from brains of patients with Alzheimer’s disease and other tauopathies, the mechanistic role of phosphorylation in tau liquid-liquid phase separation (LLPS) remains largely unexplored. In an attempt to bridge this gap, here we performed systematic studies by introducing phosphomimetic substitutions of Ser/Thr residues with negatively charged Asp/Glu residues in different regions of the protein. Our data indicate that the phosphorylation patterns that increase the polarization of charge distribution in full-length tau (tau441) promote protein LLPS, whereas those that decrease charge polarization have an opposite effect. Overall, this study further supports the notion that tau LLPS is driven by attractive intermolecular electrostatic interactions between the oppositely charged domains. We also show that the phosphomimetic tau variants with low intrinsic propensity for LLPS can be efficiently recruited to droplets formed by the variants with high LLPS propensity. Furthermore, the present data demonstrate that phosphomimetic substitutions have a major effect on time-dependent material properties of tau droplets, generally slowing down their aging. The latter effect is most dramatic for the tau variant with substitutions within the repeat domain, which correlates with the decreased fibrillation rate of this variant.