Investigation of the yeast prion factor [PSI+]

项目摘要 不同的细胞蛋白质错误折叠成淀粉样聚集体与非淀粉样变性有关。 传染性神经退行性疾病，包括阿尔茨海默氏症、亨廷顿氏症和帕金森氏症，以及 传染性朊病毒疾病，如疯牛病、鹿的慢性消瘦病和人类的克雅氏病。为每个 在这些疾病中，相关的蛋白质聚集体（“种子”）吸引其正常构象错误折叠和连接， 聚合物。简单的真核酵母中的某些蛋白质，同样可以错误折叠成传染性淀粉样蛋白 聚集体，这些聚集体引起表观遗传变异。在这项提案中，酵母遗传学的力量和 分子生物学用于研究蛋白质如何错误折叠成淀粉样聚集体，以及 这个错误折叠的细胞。酵母和人类细胞之间的广泛相似性， 模型在理解人类疾病方面做出重大贡献，这意味着这些研究可能会 与人类错误折叠的聚集蛋白有关。 由于大多数人类蛋白质错误折叠疾病的发生没有受到任何外部种子的感染， 主要研究自发性细胞淀粉样蛋白形成的分子机制。的问题 新出现的朊病毒聚集体首先出现在细胞中的何处， 与它们相关的，以及预先存在的朊病毒如何增强异源的从头出现， 朊病毒目的验证哺乳动物亨廷顿蛋白的酵母同源物Sla 2与哺乳动物亨廷顿蛋白相互作用的假说。 蛋白，促进现有朊病毒交叉接种异源朊病毒从头聚集的能力 蛋白质，通过结合到种子和待接种的蛋白质，从而使它们紧密接近。 有趣的是，人类和酵母朊病毒蛋白可以各自形成淀粉样蛋白聚集体的多种变体 它们在结构上不同，导致不同的表型或疾病病理，即使氨基酸 蛋白质的序列是相同的。目的II识别与繁殖结合和/或繁殖所需的蛋白质 几种朊病毒及其变种的基因此外，同一朊病毒的两种变体的固态核磁共振结构 将在合作者的帮助下确定。通过比较异源朊病毒，以及不同的 相同朊病毒的变体，可能是所有朊病毒的维持和感染性的共同因素， 因此，应该提供有用的药物靶点，将被确定。 虽然淀粉样蛋白的形成与疾病有关，但病理学的实际原因尚不清楚。在Aim III中， 对两种在酵母中引起毒性的朊病毒进行遗传和分子研究，将有助于确定有毒物种。 最后，酵母朊病毒不仅是人类疾病的重要模型，而且还因为它们表明， 一个重要的新的遗传变异机制在蛋白质构象水平上运作，而不是在蛋白质构象水平上运作。 核酸在Aim IV中，朊病毒是否有时能为宿主细胞提供一种 沿着，这种有利的朊病毒也可能存在于哺乳动物中。

Project Summary The misfolding of different cellular proteins into amyloid-like aggregates is associated with non- infectious neurodegenerative diseases including Alzheimer's, Huntington's and Parkinson's, as well as with the infectious prion diseases e.g. Mad Cow, Chronic Wasting in deer and Creutzfeldt-Jacob in humans. For each of these diseases, the associated protein aggregate ("seed') attracts its normal conformers to misfold and join the aggregate. Certain proteins in the simple eukaryote yeast, can likewise misfold into infectious amyloid aggregates, and these aggregates cause epigenetic variation. In this proposal, the power of yeast genetics and molecular biology is used to study how proteins misfold into amyloid-like aggregates and the consequences of this misfolding for the cell. The extensive similarity between yeast and human cells, which has enabled yeast models to make significant contributions in understanding human disease, implies that these studies will likely be relevant to misfolded aggregating proteins in humans. Since most human protein misfolding diseases occur without infection by any external seed, Aim I focuses on the molecular mechanisms surrounding spontaneous cellular amyloid formation. The questions addressed are: where do newly appearing prion aggregates first arise in cells, what other proteins are associated with them, and how do pre-existing prions enhance the de novo appearance of heterologous prions? Aim I also tests the hypothesis that Sla2, the yeast homolog of the mammalian huntingtin interacting protein, facilitates the ability of existing prions to cross-seed the de novo aggregation of heterologous prion proteins, by binding to both the seed and protein to be seeded, thereby placing them in close proximity. Interestingly, human and yeast prion proteins can each form multiple variants of amyloid aggregates that differ in structure and cause distinct phenotypes or disease pathologies, even though the amino acid sequences of the proteins are identical. Aim II identifies proteins bound to, and/or required for, the propagation of several prions and their variants. In addition, solid-state NMR structures of two variants of the same prion will be determined with the help of collaborators. By comparing heterologous prions, as well as different variants of the same prion, factors likely to be common to the maintenance and infectivity of all prions and that should therefore provide useful drug targets, will be identified. While amyloid formation is associated with disease, the actual cause of pathology is unclear. In Aim III, genetic and molecular studies of two prions that cause toxicity in yeast will help define the toxic species. Finally, yeast prions are important not only as a model for human disease, but also because they suggest an important new mechanism of genetic variation operating at the level of protein conformation rather than nucleic acids. In Aim IV the fascinating question of whether prions can sometimes provide the host cell with an advantage is explored, along with the possibility that such advantageous prions may also exist in mammals.