Conformational variations in an infectious protein determine prion strain differences
Conformational variations in an infectious protein determine prion strain differences
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DOI：
10.1038/nature02392
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发表时间：
2004-03-18
期刊：
影响因子：
64.8
通讯作者：
Weissman, JS
中科院分区：
文献类型：
--
作者：
Tanaka, M;Chien, P;Weissman, JS
朊病毒生物学的一个显著特征是应变现象，其中显然由相同蛋白质组成的朊病毒颗粒导致表型上不同的可传播状态（1-4）。为了调和毒株的存在与朊病毒传播的“仅蛋白质”假设，有人提出单个蛋白质可以错误折叠成多种不同的感染形式，每个不同的毒株对应一种感染形式（1- 3，5）。几项研究已经发现了菌株表型和朊病毒颗粒构象之间的相关性（6-10）;然而，这种差异是否导致或仅仅是朊病毒菌株的次要表现尚不清楚，主要是由于难以从纯蛋白质中产生感染性物质（3，5）。在这里，我们报告了一个高效率的协议感染酵母与[PSI+]朊病毒使用淀粉样蛋白组成的重组Sup 35片段（Sup-NM）。使用热稳定性和电子顺磁共振光谱，我们表明，在不同温度下形成的Sup-NM淀粉样蛋白采用不同的，稳定传播的构象。用这些不同的淀粉样蛋白构象感染酵母导致不同的[PSI+]菌株。这些结果证实Sup-NM在进入细胞之前采用感染性构象，满足朊病毒假说的关键预测（5）-并直接证明感染性蛋白质构象的差异决定朊病毒株变异。
A remarkable feature of prion biology is the strain phenomenon wherein prion particles apparently composed of the same protein lead to phenotypically distinct transmissible states(1-4). To reconcile the existence of strains with the 'protein-only' hypothesis of prion transmission, it has been proposed that a single protein can misfold into multiple distinct infectious forms, one for each different strain(1-3,5). Several studies have found correlations between strain phenotypes and conformations of prion particles(6-10); however, whether such differences cause or are simply a secondary manifestation of prion strains remains unclear, largely due to the difficulty of creating infectious material from pure protein(3,5). Here we report a high-efficiency protocol for infecting yeast with the [PSI+] prion using amyloids composed of a recombinant Sup35 fragment (Sup-NM). Using thermal stability and electron paramagnetic resonance spectroscopy, we demonstrate that Sup-NM amyloids formed at different temperatures adopt distinct, stably propagating conformations. Infection of yeast with these different amyloid conformations leads to different [PSI+] strains. These results establish that Sup-NM adopts an infectious conformation before entering the cell fulfilling a key prediction of the prion hypothesis(5)-and directly demonstrate that differences in the conformation of the infectious protein determine prion strain variation.