Probing the role of PrP repeats in conformational conversion and amyloid assembly of chimeric yeast prions
Probing the role of PrP repeats in conformational conversion and amyloid assembly of chimeric yeast prions
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DOI：
10.1074/jbc.m704952200
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发表时间：
2007-11-23
影响因子：
4.8
通讯作者：
Lindquist, Susan
中科院分区：
文献类型：
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作者：
Dong, Jijun;Bloom, Jesse D.;Lindquist, Susan
寡肽重复出现在许多经过构象转化形成淀粉样蛋白的蛋白质中，包括哺乳动物朊病毒蛋白 PrP 和酵母朊病毒蛋白 Sup35。尽管对 PrP 中的重复序列进行了更详尽的研究，但对这些研究的解释却因 PrP 朊病毒构象转换的许多细节尚不清楚这一事实而令人困惑。另一方面，现在对指导Sup35朊病毒蛋白构象转换的因素有了相对较好的了解。为了提供研究寡肽重复序列在朊病毒构象转化和淀粉样蛋白形成中的作用的通用模型，我们用不同数量的 PrP 八重复序列替代了内源性 Sup35 重复序列。所得嵌合蛋白可以在酵母中采用[PSI+]朊病毒状态，而朊病毒状态的稳定性取决于重复次数。在体外，这些嵌合蛋白形成淀粉样纤维，重复次数越多，滞后期越短，组装速度越快。 pH 值和金属离子的存在都会调节嵌合蛋白的组装动力学，并且调节的程度对 PrP 重复次数高度敏感。这项工作为 PrP 八重复序列在淀粉样蛋白组装和朊病毒形成中的特性提供了新的见解。它还揭示了酵母朊病毒蛋白的新特征，并提供了对酵母朊病毒组装的一定程度的控制，这将有助于未来的结构研究和创建基于淀粉样蛋白的生物材料。
Oligopeptide repeats appear in many proteins that undergo conformational conversions to form amyloid, including the mammalian prion protein PrP and the yeast prion protein Sup35. Whereas the repeats in PrP have been studied more exhaustively, interpretation of these studies is confounded by the fact that many details of the PrP prion conformational conversion are not well understood. On the other hand, there is now a relatively good understanding of the factors that guide the conformational conversion of the Sup35 prion protein. To provide a general model for studying the role of oligopeptide repeats in prion conformational conversion and amyloid formation, we have substituted various numbers of the PrP octarepeats for the endogenous Sup35 repeats. The resulting chimeric proteins can adopt the [PSI+] prion state in yeast, and the stability of the prion state depends on the number of repeats. In vitro, these chimeric proteins form amyloid fibers, with more repeats leading to shorter lag phases and faster assembly rates. Both pH and the presence of metal ions modulate assembly kinetics of the chimeric proteins, and the extent of modulation is highly sensitive to the number of PrP repeats. This work offers new insight into the properties of the PrP octarepeats in amyloid assembly and prion formation. It also reveals new features of the yeast prion protein, and provides a level of control over yeast prion assembly that will be useful for future structural studies and for creating amyloid-based biomaterials.