Mahendran Tharun Selvam, Singh Anurag, Srinivasan Sukanya, Jennings Christian M, Neureuter Christian, Gindra Bhargavi H, Parekh Sapun H, Banerjee Priya R
Department of Biological Sciences, The State University of New York at Buffalo, Buffalo, NY, 14260, USA.
Department of Physics, The State University of New York at Buffalo, Buffalo, NY, 14260, USA.
Res Sq. 2025 Apr 29:rs.3.rs-6405673. doi: 10.21203/rs.3.rs-6405673/v1.
Age-dependent transition of metastable, liquid-like protein condensates to amyloid fibrils is an emergent phenomenon of numerous neurodegeneration-linked protein systems. A key question is whether the thermodynamic forces underlying reversible phase separation and maturation to irreversible amyloids are distinct and separable. Here, we address this question using an engineered version of the microtubule-associated protein Tau, which forms biochemically active condensates. Liquid-like Tau condensates exhibit rapid aging to amyloid fibrils under quiescent, cofactor-free conditions. Tau condensate interface promotes fibril nucleation, impairing their activity to recruit tubulin and catalyze microtubule assembly. Remarkably, a small molecule metabolite, L-arginine, selectively impedes condensate-to-fibril transition without perturbing phase separation in a valence and chemistry-specific manner. By heightening the fibril nucleation barrier, L-arginine counteracts age-dependent decline in the biochemical activity of Tau condensates. These results provide a proof-of-principle demonstration that small molecule metabolites can enhance the metastability of protein condensates against a liquid-to-amyloid transition, thereby preserving condensate function.
亚稳态、类液体蛋白凝聚物向淀粉样纤维的年龄依赖性转变是众多与神经退行性变相关的蛋白质系统中出现的一种现象。一个关键问题是，可逆相分离和成熟为不可逆淀粉样蛋白背后的热力学力是否不同且可分离。在这里，我们使用微管相关蛋白Tau的工程版本来解决这个问题，该蛋白形成具有生物化学活性的凝聚物。在静态、无辅因子的条件下，类液体Tau凝聚物会迅速老化为淀粉样纤维。Tau凝聚物界面促进纤维成核，损害其招募微管蛋白和催化微管组装的活性。值得注意的是，一种小分子代谢物L-精氨酸以价态和化学特异性的方式选择性地阻碍凝聚物向纤维的转变，而不会干扰相分离。通过提高纤维成核屏障，L-精氨酸抵消了Tau凝聚物生化活性的年龄依赖性下降。这些结果提供了一个原理证明，即小分子代谢物可以增强蛋白质凝聚物对从液体到淀粉样转变的亚稳定性，从而保留凝聚物的功能。
