Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, United States.
Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, United States.
Biochemistry. 2020 Oct 6;59(39):3650-3659. doi: 10.1021/acs.biochem.0c00425. Epub 2020 Sep 21.
Misfolding of Cu, Zn superoxide dismutase (SOD1) variants may lead to protein aggregation and ultimately amyotrophic lateral sclerosis (ALS). The mechanism and protein conformational changes during this process are complex and remain unclear. To study SOD1 variant aggregation at the molecular level and in solution, we chemically induced aggregation of a mutant variant (G93A SOD1) with trifluoroethanol (TFE) and used both native mass spectrometry (MS) to analyze the intact protein and fast photochemical oxidation of proteins (FPOP) to characterize the structural changes induced by TFE. We found partially unfolded G93A SOD1 monomers prior to oligomerization and identified regions of the N-terminus, C-terminus, and strands β5, β6 accountable for the partial unfolding. We propose that exposure of hydrophobic interfaces of these unstructured regions serves as a precursor to aggregation. Our results provide a possible mechanism and molecular basis for ALS-linked SOD1 misfolding and aggregation.
铜锌超氧化物歧化酶（SOD1）变体的错误折叠可能导致蛋白质聚集，最终导致肌萎缩侧索硬化症（ALS）。在这个过程中，其机制和蛋白质构象变化非常复杂，目前尚不清楚。为了在分子水平和溶液中研究 SOD1 变体的聚集，我们使用三氟乙醇（TFE）化学诱导突变体（G93A SOD1）聚集，并使用天然质谱（MS）分析完整蛋白质和快速光化学蛋白氧化（FPOP）来表征 TFE 诱导的结构变化。我们发现寡聚化前 G93A SOD1 单体部分展开，并确定了 N 端、C 端和β5、β6 链的区域负责部分展开。我们提出，这些无结构区域的疏水面的暴露可能是聚集的前体。我们的结果为与 ALS 相关的 SOD1 错误折叠和聚集提供了一种可能的机制和分子基础。
