Redecke Lars, von Bergen Martin, Clos Joachim, Konarev Peter V, Svergun Dimitri I, Fittschen Ursula E A, Broekaert José A C, Bruns Oliver, Georgieva Dessislava, Mandelkow Eckhard, Genov Nicolay, Betzel Christian
Center of Experimental Medicine, Institute of Biochemistry and Molecular Biology I, University Hospital Hamburg-Eppendorf, c/o DESY, 22603 Hamburg, Germany.
J Struct Biol. 2007 Feb;157(2):308-20. doi: 10.1016/j.jsb.2006.06.013. Epub 2006 Jul 21.
The pathology of transmissible spongiform encephalopathies (TSEs) is strongly associated with the structural conversion of the cellular prion protein (PrPC) into a misfolded isoform (PrPSc) that assembles into amyloid fibrils. Since increased levels of oxidative stress have been linked to prion diseases, we investigated the metal-induced oxidation of human PrP (90-231). A novel in vitro conversion assay based on aerobic incubation of PrP in the presence of elemental copper pellets at pH 5 was established, resulting in aggregation of highly beta-sheeted prion proteins. We show for the first time that two discrete oligomeric species of elongated shape, approx. 25 mers and 100 mers, are formed on the pathway of oxidative PrP aggregation in vitro, which are well characterized regarding shape and size using small-angle X-ray scattering (SAXS), dynamic light scattering (DLS), and electron microscopy (EM). Considering that small oligomers of highly similar size have recently been reported to show the highest specific infectivity within TSE-infected brain tissues of hamsters, the novel oligomers observed in this study are interesting candidates as agent causing neurodegenerative and/or self-propagating effects. Moreover, our results significantly strengthen the theory that oxidative stress might be an influence that leads to substantial structural conversions of PrP in vivo.
传染性海绵状脑病（TSEs）的病理学与细胞朊蛋白（PrPC）向错误折叠异构体（PrPSc）的结构转变密切相关，PrPSc会组装成淀粉样纤维。由于氧化应激水平升高与朊病毒疾病有关，我们研究了金属诱导的人PrP（90 - 231）氧化。建立了一种基于在pH 5条件下将PrP与元素铜颗粒进行有氧孵育的新型体外转化测定法，导致高度β折叠的朊病毒蛋白聚集。我们首次表明，在体外氧化PrP聚集途径上形成了两种离散的细长形状的寡聚体物种，约25聚体和100聚体，使用小角X射线散射（SAXS）、动态光散射（DLS）和电子显微镜（EM）对其形状和大小进行了很好的表征。鉴于最近报道在仓鼠的TSE感染脑组织中，大小高度相似的小寡聚体显示出最高的特异性感染性，本研究中观察到的新型寡聚体作为导致神经退行性变和/或自我传播效应的因子是有趣的候选物。此外，我们的结果显著强化了氧化应激可能是导致体内PrP发生实质性结构转变的一种影响因素这一理论。
