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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Strain-specific sequences required for yeast [PSI~+] prion propagation
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Strain-specific sequences required for yeast [PSI~+] prion propagation

机译：酵母[PSI〜+]病毒繁殖所需的菌株特异性序列

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摘要

Amyloid polymorphism underlies the prion strain phenomenon where a single protein polypeptide adopts different chain-folding patterns to form self-propagating cross-β structures. Three strains of the yeast prion [PSI], namely [VH], [VK], and [VL], have been previously characterized and are amyloid conformers of the yeast translation termination factor Sup35. Here we define specific sequences of the Sup35 protein that are necessary for in vivo propagation of each of these prion strains. By sequential substitution of residues 5-55 of Sup35 by proline and insertion of glycine at alternate sites in this segment, specific mutations have been identified that interfere selectively with the propagation of each of the three prion strains in yeast: the [VH] strain requires amino acid residues 7-21; [VK] requires residues 9-37; and [VL] requires residues 5 to at least 52. Minimal polypeptide segments capable of encoding prion conformations were defined by assembly of re-combinant Sup35 fragments on purified prion nuclei to form amyloid fibers in vitro, whose infectivity was assayed in yeast. For the [VK] and [VL] strains, the minimal fragments approximately coincide with the strain-specific sequences defined by mutations of the N-terminal portion of the intact Sup35 (1-685); and for the [VH] strain, a longer Sup (1-53) fragment is required. Polymorphic structures of other amyloids might similarly involve different stretches of polypeptides to form cross-β amyloid cores with distinct molecular recognition surfaces.
机译：淀粉样蛋白多态性是the病毒株现象的基础，在where病毒株现象中，单个蛋白质多肽采用不同的链折叠模式以形成自传播的交叉β结构。先前已经鉴定了三种酵母病毒[PSI]菌株，即[VH]，[VK]和[VL]，它们是酵母翻译终止因子Sup35的淀粉样蛋白构象体。在这里，我们定义了这些病毒菌株中的每一个在体内繁殖所必需的Sup35蛋白的特定序列。通过脯氨酸顺序取代Sup35残基5-55，并将甘氨酸插入该片段的替代位点，已鉴定出特定的突变，这些突变选择性地干扰了三种the病毒菌株在酵母中的繁殖：[VH]菌株需要氨基酸残基7-21； [VK]要求残基9-37； [VL]需要5至至少52个残基。通过在重组的pr病毒核上组装重组Sup35片段以形成淀粉样蛋白纤维，在体外确定了能够编码病毒构象的最小多肽片段，并在酵母中测定了其感染性。对于[VK]和[VL]菌株，最小片段大约与完整Sup35（1-685）N端部分突变定义的菌株特异性序列一致；对于[VH]菌株，需要更长的Sup（1-53）片段。其他淀粉样蛋白的多态性结构可能类似地涉及不同的多肽片段，以形成具有不同分子识别表面的交叉β淀粉样蛋白核心。

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