Prion Cycle Regulation In Vivo

体内朊病毒循环调节

• 批准号: 7031895
• 负责人: TRICIA R. SERIO
• 金额: $ 28.97万
• 依托单位: BROWN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-02-01 至 2011-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7031895
• 关键词: Saccharomyces cerevisiae; cell cycle; centrifugation; chemical kinetics; chimeric proteins; conformation; enzyme activity; fluorescence resonance energy transfer; gene expression; genetic regulatory element; genetic strain; immunoprecipitation; microorganism reproduction; molecular assembly /self assembly; molecular chaperones; phenotype; prions; protein biosynthesis; protein protein interaction; protein structure function; transcription factor; transfection /expression vector; virus replication

DESCRIPTION (provided by applicant): Recent advances suggest that self-replication of protein physical states directs both the development and spread of the Transmissible Spongiform Encephalopathies and the inheritance of some phenotypic traits in lower eukaryotes. This novel biological process, known as the prion hypothesis, predicts that a unique group of proteins has the capacity to adopt multiple conformational states with distinct physiological consequences in vivo. Since one-fold-one-function proteins are unable to act in roles that have historically been linked to nucleic acids such as infectivity and inheritance, understanding how a prion protein's structure can be constrained to allow the faithful propagation of associated phenotypes but remain sufficiently flexible to allow occasional transitions in state is crucial to understanding the physiological consequences of the protein- only hypothesis. The prion cycles of lower eukaryotes provide experimentally tractable model systems for studying prion cycle regulation in vivo. For example, the Sup35 protein of S. cerevisiae is a component of the translation termination complex whose function is reversibly modulated by a prion cycle. In the non-prion state, Sup35 facilitates efficient termination (psi- phenotype), but in the prion form, Sup35's activity is compromised leading to stop codon read-through ([PSI+] phenotype). While the [PSI+] and [psi-] phenotypes are largely stable, they spontaneous interconvert (about 1 cell/million) and can be induced to quantitatively switch by chemical and molecular stimuli. Using this system, we will begin to elucidate the molecular mechanism underlying the near-faithful propagation of prion forms in vivo by focusing on two contributing factors: the interplay of distinct forms when present in the same cell and the trans regulators of efficient prion conversion. Toward this end, we will 1) determine the molecular basis of prion variant dominance in vivo, 2) elucidate the molecular mechanisms by which known regulators of the Sup35/[PSI+] prion cycle modulate propagation and phenotypic transitions, and 3) screen for and characterize novel prion regulators. Together, these lines of investigation will build a framework for understanding protein-only phenotypic propagation in terms of prion protein biogenesis. A strong foundation of previous work indicates that the knowledge gleaned from prion studies in lower eukaryotes is clearly and directly applicable to our understanding of prion mechanisms and their physiological consequences in mammals.

描述（由申请人提供）：最近的进展表明，蛋白质物理状态的自我复制指导了传染性海绵状脑病的发展和传播以及低等真核生物中一些​​表型性状的遗传。这种新的生物过程被称为朊病毒假说，它预测一组独特的蛋白质有能力采取多种构象状态，在体内产生不同的生理后果。由于单一功能蛋白无法发挥历史上与核酸相关的作用，例如感染性和遗传性，因此了解如何限制朊病毒蛋白的结构以允许相关表型的忠实传播，但保持足够的灵活性允许偶尔的状态转变对于理解纯蛋白质假说的生理后果至关重要。低等真核生物的朊病毒循环为研究体内朊病毒循环调节提供了实验上易于处理的模型系统。例如，酿酒酵母的 Sup35 蛋白是翻译终止复合物的一个组成部分，其功能受到朊病毒循环的可逆调节。在非朊病毒状态下，Sup35 促进有效终止（psi-表型），但在朊病毒形式下，Sup35 的活性受到损害，导致终止密码子通读（[PSI+] 表型）。虽然 [PSI+] 和 [psi-] 表型基本稳定，但它们会自发相互转换（约 1 个细胞/百万），并且可以通过化学和分子刺激诱导定量转换。使用该系统，我们将通过关注两个影响因素开始阐明朊病毒形式在体内近乎忠实传播的分子机制：存在于同一细胞中的不同形式的相互作用以及有效朊病毒转化的反式调节因子。为此，我们将 1) 确定体内朊病毒变异优势的分子基础，2) 阐明 Sup35/[PSI+] 朊病毒循环的已知调节因子调节传播和表型转变的分子机制，以及 3) 筛选和描述新型朊病毒调节剂的特征。总之，这些研究路线将构建一个框架，用于理解朊病毒蛋白生物发生方面的纯蛋白质表型传播。先前工作的坚实基础表明，从低等真核生物的朊病毒研究中收集到的知识显然直接适用于我们对哺乳动物中朊病毒机制及其生理后果的理解。