Hosseini Faradonbeh Seyed Mahdi, Seyedalipour Bagher, Keivan Behjou Nasrin, Rezaei Kimiya, Baziyar Payam, Hosseinkhani Saman
Department of Molecular and Cell Biology, Faculty of Basic Science, University of Mazandaran, Babolsar, Iran.
Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran.
Front Mol Biosci. 2025 Feb 25;12:1532375. doi: 10.3389/fmolb.2025.1532375. eCollection 2025.
Protein stability is a crucial characteristic that influences both protein activity and structure and plays a significant role in several diseases. Cu/Zn superoxide dismutase 1 (SOD1) mutations serve as a model for elucidating the destabilizing effects on protein folding and misfolding linked to the lethal neurological disease, amyotrophic lateral sclerosis (ALS). In the present study, we have examined the structure and dynamics of the SOD1 protein upon two ALS-associated point mutations at the surface (namely, E49K and R115G), which are located in metal-binding loop IV and Greek key loop VI, respectively. Our analysis was performed through multiple algorithms on the structural characterization of the hSOD1 protein using computational predictions, molecular dynamics (MD) simulations, and experimental studies to understand the effects of amino acid substitutions. Predictive results of computational analysis predicted the deleterious and destabilizing effect of mutants on hSOD1 function and stability. MD outcomes also indicate that the mutations result in structural destabilization by affecting the increased content of β-sheet structures and loss of hydrogen bonds. Moreover, comparative intrinsic and extrinsic fluorescence results of WT-hSOD1 and mutants indicated structural alterations and increased hydrophobic surface pockets, respectively. As well, the existence of β-sheet-dominated structures was observed under amyloidogenic conditions using FTIR spectroscopy. Overall, our findings suggest that mutations in the metal-binding loop IV and Greek key loop VI lead to significant structural and conformational changes that could affect the structure and stability of the hSOD1 molecule, resulting in the formation of toxic intermediate species that cause ALS.
蛋白质稳定性是一个关键特性，它影响蛋白质的活性和结构，并且在多种疾病中起着重要作用。铜/锌超氧化物歧化酶1（SOD1）突变可作为一个模型，用于阐明对与致死性神经疾病肌萎缩侧索硬化症（ALS）相关的蛋白质折叠和错误折叠的去稳定化作用。在本研究中，我们研究了位于表面的两个与ALS相关的点突变（即E49K和R115G）对SOD1蛋白的结构和动力学的影响，这两个突变分别位于金属结合环IV和希腊钥匙环VI中。我们通过多种算法，利用计算预测、分子动力学（MD）模拟和实验研究对hSOD1蛋白的结构特征进行分析，以了解氨基酸取代的影响。计算分析的预测结果预测了突变体对hSOD1功能和稳定性的有害和去稳定化作用。MD结果还表明，这些突变通过影响β-折叠结构含量的增加和氢键的丧失导致结构不稳定。此外，WT-hSOD1和突变体的比较内在和外在荧光结果分别表明了结构改变和疏水表面口袋增加。同样，在淀粉样变性条件下使用傅里叶变换红外光谱观察到了以β-折叠为主的结构的存在。总体而言，我们的研究结果表明，金属结合环IV和希腊钥匙环VI中的突变导致了显著的结构和构象变化，这可能会影响hSOD1分子的结构和稳定性，从而导致导致ALS的有毒中间物种的形成。
