Abstract：
Many RNA binding proteins (RBPs) contain low-complexity domains (LCDs) with prion-like compositions. These long intrinsically disordered regions regulate their solubility, contributing to their physiological roles in RNA processing and organization. However, this also makes these RBPs prone to pathological misfolding and aggregation that are characteristic of neurodegenerative diseases. For example, TAR DNA-binding protein 43 (TDP-43) forms pathological aggregates associated with amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). While molecular chaperones are well-known suppressors of these aberrant events, we recently reported that highly disordered, hydrophilic and charged heat-resistant obscure (Hero) proteins may have similar effects. Specifically, Hero proteins can maintain the activity of other proteins from denaturing conditions in vitro, while their overexpression can suppress cellular aggregation and toxicity associated with aggregation-prone proteins. However, it is unclear how these protective effects are achieved. Here, we utilized single-molecule FRET to monitor the conformations of the aggregation-prone prion-like LCD of TDP-43. While we observed high conformational heterogeneity in wild-type LCD, the ALS-associated mutation A315T promoted collapsed conformations. In contrast, an Hsp40 chaperone, DNAJA2, and a Hero protein, Hero11 stabilized extended states of the LCD, consistent with their ability to suppress the aggregation of TDP-43. Our results link single-molecule effects on conformation to macro effects on bulk aggregation, where a Hero protein, like a chaperone, can maintain the conformational integrity of a client protein to prevent its aggregation.
摘要：
许多RNA结合蛋白(RBP)包含具有朊病毒样组成的低复杂度结构域(LCD)。这些长的内在无序区域调节它们的溶解度，有助于它们在RNA加工和组织中的生理作用。然而,这也使得这些RBP易于发生病理错误折叠和聚集,这是神经退行性疾病的特征.例如,TARDNA结合蛋白43（TDP-43）形成与肌萎缩侧索硬化症（ALS）和额颞叶变性（FTLD）相关的病理性聚集体。虽然分子伴侣是众所周知的这些异常事件的抑制剂，我们最近报道了高度无序，亲水和带电的耐热晦涩（英雄）蛋白可能有类似的效果。具体来说,英雄蛋白可以在体外保持其他蛋白的变性条件的活性，而它们的过表达可以抑制与聚集倾向蛋白相关的细胞聚集和毒性。然而,目前尚不清楚这些保护作用是如何实现的。这里,我们利用单分子FRET监测TDP-43易于聚集的朊病毒样LCD的构象.虽然我们在野生型LCD中观察到高构象异质性，ALS相关突变A315T促进了折叠构象。相比之下,Hsp40监护人,DNAJA2和英雄蛋白,Hero11稳定了LCD的扩展状态，与它们抑制TDP-43聚集的能力一致。我们的结果将单分子对构象的影响与对整体聚集的宏观影响联系起来，英雄蛋白，像一个监护人，可以保持客户蛋白的构象完整性以防止其聚集。
