Prion Cycle Regulation In Vivo

最近的进展表明，蛋白质物理状态的自我复制既指导着蛋白质的发育，也指导着蛋白质物理状态的发展 传染性海绵状脑病的流行及部分表型性状的遗传 低等真核生物。这一新的生物过程，被称为普瑞恩假说，预测了一个独特的群体 具有采用多种构象状态的能力，具有不同的生理结果 在活体内。因为一重一功能蛋白质不能发挥历史上与 核酸，如传染性和遗传性，了解Pron蛋白质的结构 被限制为允许相关表型的忠实繁殖，但保持足够的灵活性 允许偶尔的状态转换对于理解蛋白质的生理后果至关重要- 只是假设。 低等真核生物的蛋白循环为研究蛋白提供了易于实验处理的模型系统 体内循环调节。例如，酿酒酵母的Sup35蛋白是翻译的一个组成部分 终末复合体，其功能可逆地由蛋白循环调节。在非Prion状态下，Sup35 有助于有效终止(\pst)表型，但在Prion形式中，Sup35‘S的活性受到损害 导致停止密码子通读([PSI+]表型)。而[PSI+]和[PST]表型主要是 稳定，它们自发转换(~1 cell/百万)，并可通过以下方式诱导定量转换 化学和分子刺激。 利用这个系统，我们将开始阐明近乎忠诚的人背后的分子机制 通过关注两个贡献因素：不同形式的相互作用，在体内传播Pron形式 当存在于同一细胞中时，反式调节蛋白有效地进行了蛋白的转化。为此，我们将 1)确定体内PrP变异优势的分子基础；2)阐明其分子机制 已知的Sup35/[PS/+]Prion循环调节因子的繁殖和表型转换， 3)筛选和鉴定新的普里恩调节子。总之，这些调查将建立一个 从蛋白质生物发生的角度理解纯蛋白质表型繁殖的框架。一个 以往工作的坚实基础表明，从较低的蛋白质研究中收集到的知识 真核生物清楚而直接地适用于我们对普恩病毒机制及其 哺乳动物的生理后果。

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 uniquegroup of proteins has the capacity to adopt multiple conformational states with distinct physiological consequences in vivo. Since one-fold-one-function proteins are unableto act in roles that have historically been linked to nucleic acids such as infectivity and inheritance, understandinghow 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 eukaryotesprovide experimentally tractable model systems for studyingprion cycle regulation in vivo. For example, the Sup35 protein of S. cerevisiae is a component of the translation termination complex whose function is reversibly modulatedby a prion cycle. In the non-prion state, Sup35 facilitates efficient termination (\pst] phenotype), but in the prion form, Sup35's activity is compromised leading to stop codon read-through ([PSI+] phenotype). While the [PSI+] and [pst] phenotypes are largely stable, they spontaneous interconvert (~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 underlyingthe near-faithful propagation of prion forms in vivo by focusing on two contributingfactors: 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 knownregulators of the Sup35/[PS/+] prion cycle modulatepropagation and phenotypic transitions, and 3) screen for and characterize novel prion regulators. Together, these lines of investigation will build a framework for understandingprotein-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 understandingof prion mechanisms and their physiological consequences in mammals.