Inserm, U 554, Montpellier, France.
PLoS One. 2010 Oct 8;5(10):e13240. doi: 10.1371/journal.pone.0013240.
Formation of fibrillar structures of proteins that deposit into aggregates has been suggested to play a key role in various neurodegenerative diseases. However mechanisms and dynamics of fibrillization remains to be elucidated. We have previously established that lithostathine, a protein overexpressed in the pre-clinical stages of Alzheimer's disease and present in the pathognomonic lesions associated with this disease, form fibrillar aggregates after its N-terminal truncation. In this paper we visualized, using high-speed atomic force microscopy (HS-AFM), growth and assembly of lithostathine protofibrils under physiological conditions with a time resolution of one image/s. Real-time imaging highlighted a very high velocity of elongation. Formation of fibrils via protofibril lateral association and stacking was also monitored revealing a zipper-like mechanism of association. We also demonstrate that, like other amyloid ß peptides, two lithostathine protofibrils can associate to form helical fibrils. Another striking finding is the propensity of the end of a growing protofibril or fibril to associate with the edge of a second fibril, forming false branching point. Taken together this study provides new clues about fibrillization mechanism of amyloid proteins.
蛋白质纤维结构的形成被认为在各种神经退行性疾病中起关键作用。然而，纤维化的机制和动力学仍有待阐明。我们之前已经证实，在阿尔茨海默病的临床前阶段过度表达并存在于与该疾病相关的特征性病变中的石胆蛋白，在其 N 端截断后会形成纤维状聚集物。在本文中，我们使用高速原子力显微镜 (HS-AFM) 在生理条件下以每秒一张图像的时间分辨率可视化观察石胆蛋白原纤维的生长和组装。实时成像突出显示了非常高的伸长速度。通过原纤维的侧向缔合和堆积形成纤维也被监测到，揭示了拉链样的缔合机制。我们还证明，与其他淀粉样 β 肽一样，两条石胆蛋白原纤维可以缔合形成螺旋纤维。另一个引人注目的发现是，生长中的原纤维或纤维的末端倾向于与第二根纤维的边缘缔合，形成虚假分支点。总之，这项研究为淀粉样蛋白的纤维化机制提供了新的线索。
