Shukla A, Raje M, Guptasarma P
Institute of Microbial Technology, Chandigarh 160036, India.
Biochemistry (Mosc). 2008 Jun;73(6):681-5. doi: 10.1134/s0006297908060084.
The sequence-reversed form of a small heat shock protein, HSP12.6 (retro-HSP12.6), has been reported to fold and assemble into structured tetramers in aqueous solution. Upon raising the protein concentration to ~1.0-1.5 mg/ml, tetrameric retro-HSP12.6 is known to display a tendency to associate further into spherical beads of 18-20 nm in diameter containing folded protein subunits. Here we report that storage of this protein at low temperatures leads to further association of the beaded structures into linear and ring-shaped amyloid nanofibers of 18-20 nm in diameter. The electron micrographs presented in this communication provide the best visual evidence yet that amyloids can form through the association of smaller structured bead-like intermediates. The results also suggest that folded beta-sheet-rich subunits can participate in amyloid formation.
据报道，一种小热休克蛋白HSP12.6的序列反转形式（反转HSP12.6）在水溶液中折叠并组装成结构化的四聚体。当蛋白质浓度提高到约1.0-1.5mg/ml时，已知四聚体反转HSP12.6有进一步缔合形成直径为18-20nm的球形珠的趋势，这些球形珠包含折叠的蛋白质亚基。在此我们报告，将这种蛋白质在低温下储存会导致珠状结构进一步缔合形成直径为18-20nm的线性和环形淀粉样纳米纤维。本通讯中呈现的电子显微镜照片提供了迄今为止最好的视觉证据，证明淀粉样蛋白可以通过较小的结构化珠状中间体的缔合形成。结果还表明，富含β-折叠的折叠亚基可以参与淀粉样蛋白的形成。
