School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul, Republic of Korea.
PLoS One. 2011;6(12):e28982. doi: 10.1371/journal.pone.0028982. Epub 2011 Dec 28.
Interactions between protein aggregates and a cellular membrane have been strongly implicated in many protein conformational diseases. However, such interactions for the case of Cu/Zn superoxide dismutase (SOD1) protein, which is related to fatal neurodegenerative disorder amyotrophic lateral sclerosis (ALS), have not been explored yet. For the first time, we report the direct observation of defect formation and increased ion permeability of a membrane induced by SOD1 aggregates using a supported lipid bilayer and membrane patches of human embryonic kidney cells as model membranes. We observed that aggregated SOD1 significantly induced the formation of defects within lipid membranes and caused the perturbation of membrane permeability, based on surface plasmon resonance spectroscopy, atomic force microscopy and electrophysiology. In the case of apo SOD1 with an unfolded structure, we found that it bound to the lipid membrane surface and slightly perturbed membrane permeability, compared to other folded proteins (holo SOD1 and bovine serum albumin). The changes in membrane integrity and permeability were found to be strongly dependent on the type of proteins and the amount of aggregates present. We expect that the findings presented herein will advance our understanding of the pathway by which structurally disordered SOD1 aggregates exert toxicity in vivo.
蛋白质聚集体与细胞膜之间的相互作用强烈暗示了许多蛋白质构象疾病。然而，对于与致命的神经退行性疾病肌萎缩性侧索硬化症（ALS）相关的 Cu/Zn 超氧化物歧化酶（SOD1）蛋白，这种相互作用尚未得到探索。我们首次使用支持脂双层和人胚肾细胞的膜片作为模型膜，直接观察到 SOD1 聚集体诱导的膜缺陷形成和离子通透性增加。基于表面等离子体共振光谱、原子力显微镜和电生理学，我们观察到聚集的 SOD1 显著诱导脂质膜内缺陷的形成，并导致膜通透性的扰动。在无折叠结构的 apo SOD1 情况下，与其他折叠蛋白（全酶 SOD1 和牛血清白蛋白）相比，我们发现它结合在脂质膜表面，仅轻微扰动膜通透性。发现膜完整性和通透性的变化强烈依赖于蛋白质的类型和存在的聚集体的量。我们期望本文的研究结果将有助于我们理解结构无序的 SOD1 聚集体在体内发挥毒性的途径。
