Instituto de Química Física "Rocasolano", CSIC, Serrano 119, Madrid, 28006, Spain.
Instituto Cajal, CSIC, Avda. Doctor Arce 37, Madrid, 28002, Spain.
Arch Biochem Biophys. 2019 Oct 30;675:108113. doi: 10.1016/j.abb.2019.108113. Epub 2019 Sep 27.
Transactive Response DNA-Binding Protein of 43 kDa (TDP-43) is an essential human protein implicated in Amyotrophic Lateral Sclerosis (ALS) and common dementias. Its C-terminal disordered region, composed of residues 264-414 includes a hydrophobic segment (residues 320-340), which drives physiological liquid/liquid phase separation and a Q/N-rich segment (residues 341-357), which is essential for pathological amyloid formation. Due to TDP-43's relevance for pathology, identifying inhibitors and characterizing their mechanism of action are important pharmacological goals. The Polyglutamine Binding Peptide 1 (QBP1), whose minimal active core is the octapeptide WGWWPGIF, strongly inhibits the aggregation of polyQ-containing amyloidogenic proteins such as Huntingtin. Rather promiscuous, this inhibitor also blocks the aggregation of other glutamine containing amyloidogenic proteins, but not Aβ, and its mechanism of action remains unknown. Using a series of spectroscopic assays and biochemical tests, we establish that QBP1 binds and inhibits amyloid formation by TDP-43's Q/N-rich region. NMR spectroscopic data evince that the aromatic rings of QBP1 accept hydrogen bonds from the HN groups of the Asn and Gln to block amyloidogenesis. This mechanism of blockage may be general to polyphenol amyloid inhibitors.
43kDa 转译反应 DNA 结合蛋白（TDP-43）是一种重要的人类蛋白，与肌萎缩性侧索硬化症（ALS）和常见痴呆症有关。其 C 端无规卷曲结构域由残基 264-414 组成，包括一个疏水区（残基 320-340），该区域驱动生理液体/液相分离和一个富含 Q/N 的区域（残基 341-357），对于病理性淀粉样形成是必需的。由于 TDP-43 与病理学有关，因此鉴定抑制剂并描述其作用机制是重要的药理学目标。聚谷氨酰胺结合肽 1（QBP1）的最小活性核心是八肽 WGWWPGIF，它强烈抑制含有聚谷氨酰胺的淀粉样蛋白原纤维形成，如亨廷顿蛋白。这种抑制剂具有较强的非特异性，它还可以阻止其他含有谷氨酰胺的淀粉样蛋白原纤维的聚集，但不能阻止 Aβ的聚集，其作用机制尚不清楚。我们使用一系列光谱测定和生化测试，确定 QBP1 结合并抑制 TDP-43 的富含 Q/N 区域的淀粉样形成。NMR 光谱数据表明，QBP1 的芳环接受来自 Asn 和 Gln 的 HN 基团的氢键，从而阻断淀粉样形成。这种阻断机制可能对多酚类淀粉样抑制剂具有普遍性。
