Protein-only transmission of three yeast prion strains
Protein-only transmission of three yeast prion strains
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DOI：
10.1038/nature02391
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发表时间：
2004-03-18
期刊：
影响因子：
64.8
通讯作者：
Diaz-Avalos, R
中科院分区：
文献类型：
--
作者：
King, CY;Diaz-Avalos, R
关于朊病毒分子性质的关键问题是不同的朊病毒株如何通过相同的蛋白质繁殖，以及它们是否只是蛋白质（1-3）。在这里，我们证明了朊病毒菌株在酵母模型中的蛋白质性质，[ PSI]遗传元件增强了酵母酿酒酵母中无义突变的通读（4，5）。感染性纤维聚集体含有Sup 35朊病毒决定氨基末端片段标记的绿色荧光蛋白纯化酵母窝藏独特的朊病毒菌株。使用感染性聚集体作为“种子”，从细菌表达的标记朊病毒蛋白在体外产生细长的纤维。从头产生的菌株特异性[ PSI]感染性被证明是通过将剪切纤维引入未感染的酵母宿主。在体外产生的细长纤维的横截面形态是无法区分的短酵母种子，如通过电子显微镜观察。长纤维的电子衍射显示淀粉样蛋白的交叉β结构的4.7埃间距特征。体外成核的淀粉样纤维传播酵母种子的菌株特异性感染性的事实意味着不同朊病毒菌株的可遗传信息必须由相同朊病毒蛋白的不同的、自传播的交叉β折叠模式编码。
Key questions regarding the molecular nature of prions are how different prion strains can be propagated by the same protein and whether they are only protein(1-3). Here we demonstrate the protein-only nature of prion strains in a yeast model, the [ PSI] genetic element that enhances the read-through of nonsense mutations in the yeast Saccharomyces cerevisiae(4,5). Infectious fibrous aggregates containing a Sup35 prion-determining amino-terminal fragment labelled with green fluorescent protein were purified from yeast harbouring distinctive prion strains. Using the infectious aggregates as 'seeds', elongated fibres were generated in vitro from the bacterially expressed labelled prion protein. De novo generation of strain-specific [ PSI] infectivity was demonstrated by introducing sheared fibres into uninfected yeast hosts. The cross-sectional morphology of the elongated fibres generated in vitro was indistinguishable from that of the short yeast seeds, as visualized by electron microscopy. Electron diffraction of the long fibres showed the 4.7 Angstrom spacing characteristic of the cross-beta structure of amyloids. The fact that the amyloid fibres nucleated in vitro propagate the strain-specific infectivity of the yeast seeds implies that the heritable inforletters mation of distinct prion strains must be encoded by different, self-propagating cross-beta folding patterns of the same prion protein.