Structure/Mechanism of a Prion-remodeling Factor

描述(申请人提供)：病毒是一种具有高度传染性的蛋白质类物质，可导致几种毁灭性且总是致命的神经退行性疾病。例子包括人类的克雅氏病和库鲁病，牛的牛海绵状脑病，以及麋鹿和鹿的慢性消耗性疾病。我们研究的广泛和长期目标是促进我们对普恩和普恩疾病的分子理解。 [PSI]是一种酵母蛋白，可以增加无意义密码子的翻译通读。像哺乳动物的蛋白一样，酵母蛋白蛋白完全由蛋白质组成。[PSI]是由Sup35的自身复制的淀粉样构象形成的，最终导致淀粉样纤维的形成，这是Pron疾病的标志。最有趣的是，[PSI]的遗传、繁殖和消除是由Hsp104分子伴侣控制的。Hsp104首先被发现是酵母应激反应的重要组成部分，是一种依赖于ATP的蛋白质重塑因子，可以将应激损伤的蛋白质从先前聚集的状态中拯救出来。虽然解聚蛋白质的能力与细菌ClpB相同，但ClpB既不促进繁殖，也不促进[PSI]的消除，这表明Prion重塑和蛋白质解聚活动在机械上是不同的。 这项提议的目的是提供对Hsp104在原癌发生中的作用的详细的机制的理解。具体目标如下：(1)确定Hsp104的高分辨晶体结构；(2)剖析Hsp104蛋白重塑活性的生化机制；(3)确定Hsp104/Sup35复合体的三维结构。为了实现我们的目标，我们将把三维结构研究与生化和高通量蛋白质组学方法结合起来。这些技术的结合将为Pron重塑的机制提供实质性的新见解，Pron重塑是HSP104特有的活动。此外，我们提出的研究也可能为为什么分子伴侣不能预防普恩病毒感染提供答案，并可能在寻找普恩病毒感染和其他蛋白质错误折叠疾病的潜在治疗方法方面开辟新的途径。 Prion是一种非常规的、高度传染性的病原体，可导致几种毁灭性且总是致命的神经退行性疾病，统称为传染性海绵状脑病。分子伴侣提供了抵御蛋白感染和其他蛋白质错误折叠疾病的第一道防线。在这里，我们将研究Hsp104的结构和机制，Hsp104是一种PrP重塑因子，也是应激反应的基本分子伴侣。

DESCRIPTION (provided by applicant): Prions are highly infectious proteinaceous agents responsible for several devastating and invariably fatal neurodegenerative diseases. Examples include Creutzfeldt-Jacob disease and kuru in humans, bovine spongiform encephalopathy in cattle, and chronic wasting diseases in elk and deer. The broad and long-term objective of our research is to further our molecular understanding of prions and prion diseases. [PSI+] is a yeast prion that increases translational read-through of nonsense codons. Like mammalian prions, yeast prions consist entirely of protein. [PSI+] is formed by self-replicating amyloid conformers of Sup35, which ultimately result in the formation of amyloid fibrils, a hallmark of prion diseases. Most interestingly, the inheritance, propagation, and elimination of [PSI+] are governed by the Hsp104 molecular chaperone. First discovered as an essential component in the yeast stress response, Hsp104 is an ATP-dependent protein- remodeling factor, which can rescue stress-damaged proteins from a previously aggregated state. While the ability to disaggregate proteins is shared with bacterial ClpB, ClpB neither promotes propagation nor facilitates elimination of [PSI+], suggesting that prion-remodeling and protein-disaggregating activities are mechanistically distinct. The goal of this proposal is to provide a detailed mechanistic understanding of the role of Hsp104 in prionogenesis. The following specific aims are proposed: (1) to determine the high-resolution crystal structure of Hsp104, (2) to dissect the biochemical mechanism of Hsp104 prion-remodeling activity, and (3) to determine the 3D structure of an Hsp104/Sup35 complex. To achieve our goals, we will combine three-dimensional structural studies with biochemical and high-throughput proteomic approaches. The combination of these techniques will provide substantial new insight into the mechanism of prion remodeling, an activity unique to Hsp104. Moreover, our proposed studies may also provide answers to why molecular chaperones cannot prevent prion infections, and may open new avenues in the search for a potential treatment of prion infections and other protein misfolding diseases. Prions are unconventional, highly infectious agents, responsible for several devastating and invariably fatal neurodegenerative diseases collectively known as transmissible spongiform encephalopathies. Molecular chaperones provide the first line of defense against prion infections and other protein misfolding diseases. Here we will investigate the structure and mechanism of Hsp104, a prion-remodeling factor and essential molecular chaperone of the stress response.