TDP‐43 forms the primary constituents of the cytoplasmic inclusions contributing to various neurodegenerative diseases, including amyotrophic lateral sclerosis and frontotemporal dementia (FTD). Over 60 TDP‐43 mutations have been identified in patients suffering from these two diseases, but most variations are located in the protein's disordered C‐terminal glycine‐rich region. P112H mutation of TDP‐43 has been uniquely linked to FTD, and is located in the first RNA recognition motif (RRM1). This mutation is thought to be pathogenic, but its impact on TDP‐43 at the protein level remains unclear. Here, we compare the biochemical and biophysical properties of TDP‐43 truncated proteins with or without P112H mutation. We show that P112H‐mutated TDP‐43 proteins exhibit higher thermal stability, impaired RNA‐binding activity, and a reduced tendency to aggregate relative to wild‐type proteins. Near‐UV CD, 2D‐nuclear‐magnetic resonance, and intrinsic fluorescence spectrometry further reveal that the P112H mutation in RRM1 generates local conformational changes surrounding the mutational site that disrupt the stacking interactions of the W113 side chain with nucleic acids. Together, these results support the notion that P112H mutation of TDP‐43 contributes to FTD through functional impairment of RNA metabolism and/or structural changes that curtail protein clearance.

中文翻译：

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TDP-43的额颞叶痴呆相关的P112H突变诱导蛋白质结构变化并损害其RNA结合功能

TDP-43 是导致各种神经退行性疾病的细胞质包涵体的主要成分，包括肌萎缩侧索硬化症和额颞叶痴呆 (FTD)。在患有这两种疾病的患者中已鉴定出超过 60 种 TDP-43 突变，但大多数变异位于蛋白质无序的 C 末端富含甘氨酸的区域。TDP-43 的 P112H 突变与 FTD 唯一相关，位于第一个 RNA 识别基序 (RRM1)。这种突变被认为是致病的，但其在蛋白质水平上对 TDP-43 的影响仍不清楚。在这里，我们比较了有或没有 P112H 突变的 TDP-43 截短蛋白的生化和生物物理特性。我们表明 P112H 突变的 TDP-43 蛋白表现出更高的热稳定性，受损的 RNA 结合活性，并且相对于野生型蛋白质减少聚集的趋势。近紫外 CD、二维核磁共振和本征荧光光谱法进一步表明，RRM1 中的 P112H 突变会在突变位点周围产生局部构象变化，从而破坏 W113 侧链与核酸的堆积相互作用。总之，这些结果支持了这样一种观点，即 TDP-43 的 P112H 突变通过 RNA 代谢的功能障碍和/或减少蛋白质清除的结构变化导致 FTD。和内在荧光光谱法进一步表明，RRM1 中的 P112H 突变会在突变位点周围产生局部构象变化，从而破坏 W113 侧链与核酸的堆积相互作用。总之，这些结果支持了这样一种观点，即 TDP-43 的 P112H 突变通过 RNA 代谢的功能障碍和/或减少蛋白质清除的结构变化导致 FTD。和内在荧光光谱法进一步表明，RRM1 中的 P112H 突变会在突变位点周围产生局部构象变化，从而破坏 W113 侧链与核酸的堆积相互作用。总之，这些结果支持了这样一种观点，即 TDP-43 的 P112H 突变通过 RNA 代谢的功能障碍和/或减少蛋白质清除的结构变化导致 FTD。