Redecke Lars, Binder Stephan, Elmallah Mohammed I Y, Broadbent Rebecca, Tilkorn Claudia, Schulz Benjamin, May Patrick, Goos Arne, Eich Andreas, Rübhausen Michael, Betzel Christian
Institute of Biochemistry and Molecular Biology, Department of Chemistry, University of Hamburg, Germany.
Free Radic Biol Med. 2009 May 15;46(10):1353-61. doi: 10.1016/j.freeradbiomed.2009.02.013. Epub 2009 Feb 26.
Increasing evidence suggests a central role for oxidative stress in the pathology of prion diseases, a group of fatal neurodegenerative disorders associated with structural conversion of the prion protein (PrP). Because UV-light-induced protein damage is mediated by direct photo-oxidation and radical reactions, we investigated the structural consequences of UVB radiation on recombinant murine and human prion proteins at pH 7.4 and pH 5.0. As revealed by circular dichroism and dynamic light scattering measurements, the observed PrP aggregation follows two independent pathways: (i) complete unfolding of the protein structure associated with rapid precipitation or (ii) specific structural conversion into distinct soluble beta-oligomers. The choice of pathway was directly attributed to the chromophoric properties of the PrP species and the susceptibility to oxidation. Regarding size, the oligomers characterized in this study share a high degree of identity with oligomeric species formed after structural destabilization induced by other triggers, which significantly strengthens the theory that partly unfolded intermediates represent initial precursor molecules directing the pathway of PrP aggregation. Moreover, we identified the first suitable photo-trigger capable of inducing refolding of PrP, which has an important biotechnological impact in terms of analyzing the conversion process on small time scales.
越来越多的证据表明，氧化应激在朊病毒疾病的病理过程中起着核心作用，朊病毒疾病是一组与朊病毒蛋白（PrP）结构转变相关的致命神经退行性疾病。由于紫外线诱导的蛋白质损伤是由直接光氧化和自由基反应介导的，我们研究了UVB辐射对重组小鼠和人朊病毒蛋白在pH 7.4和pH 5.0条件下的结构影响。圆二色性和动态光散射测量结果表明，观察到的PrP聚集遵循两条独立的途径：（i）与快速沉淀相关的蛋白质结构完全展开，或（ii）特异性结构转变为不同的可溶性β-寡聚体。途径的选择直接归因于PrP物种的发色特性和氧化敏感性。就大小而言，本研究中表征的寡聚体与其他触发因素诱导结构不稳定后形成的寡聚体物种具有高度的一致性，这显著强化了部分展开的中间体代表指导PrP聚集途径的初始前体分子的理论。此外，我们鉴定出了第一种能够诱导PrP重折叠的合适光触发剂，这在小时间尺度上分析转化过程方面具有重要的生物技术影响。
