Protein unfolding in a physiological system

蛋白质在生理系统中的展开

• 批准号: 6636634
• 负责人: ANDREAS MATOUSCHEK
• 金额: $ 25.73万
• 依托单位: NORTHWESTERN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-04-01 至 2006-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6636634
• 关键词: Saccharomyces cerevisiae; autoradiography; bacterial proteins; cell free system; chemical stability; computer simulation; dihydrofolate reductase; electrochemistry; heat shock proteins; intermolecular interaction; intracellular transport; membrane potentials; mitochondria; mitochondrial membrane; molecular chaperones; molecular site; nuclear magnetic resonance spectroscopy; phosphodiesterases; protein biosynthesis; protein folding; protein signal sequence; protein structure function; protein transport; radiotracer; thermodynamics

Description (provided by applicant): Regulated unfolding is critically important in the lifecycle of many proteins, such as those translocated across mitochondrial and chloroplast membranes, as well as those degraded by ATP-dependent proteases such as the proteasome. About half of all proteins synthesized in the eukaryotic cell are transported into or across a membrane. The protein translocation machineries are well defined biologically, but the means by which they transport and unfold proteins are not well understood at the biochemical and biophysical level. In contrast to protein folding, the mechanism of protein unfolding in the living cell has not been studied previously. The aims of this proposal are to understand the structural changes that occur in the unfolding protein prior to translocation and the molecular mechanisms of the unfolding machinery. The pathways of unfolding for a range of model proteins that translocate across membranes will be determined and compared with the pathway of spontaneous unfolding in solution. The mechanism of the unfoldase will be determined by inhibiting candidates either chemically or by mutation and measuring the effect on unfolding. The components of the import machinery that contribute to unfolding will be identified and the way in which they interact with each other the substrate protein determined. The hypothesis that the machinery unravels proteins by a physical pulling mechanism will be tested. This information is necessary to understand protein unfolding processes in the cell and to understand the function of a complex protein machine. The conclusions will also have broad implications for the understanding of protein translocation processes in the cell, in particular on the mechanisms that provide specificity to protein targeting to membranes. Interestingly, the unfolding processes during translocation and degradation share mechanistic features. Finally, the subject is directly relevant to human diseases. For example, an inherited form of oxalosis is due to the miss-sorting of an enzyme from peroxisomes to mitochondria. Since unfolding is not required for import into peroxisomes and the miss-sorted protein contains functional peroxisomal targeting information, preventing unfolding should correct the sorting defect.

描述（由申请人提供）：受监管的展开是至关重要的 在许多蛋白质的生命周期中重要 线粒体和叶绿体膜，以及降解的膜 ATP依赖性蛋白酶，例如蛋白酶体。所有蛋白质的一半 在真核细胞中合成的人转运到膜中或穿过膜。 蛋白质转运机器在生物学上是很好的，但是 他们运输和展开蛋白质的手段尚不清楚 生化和生物物理水平。与蛋白质折叠相反， 尚未研究活细胞中蛋白质的机制 之前。 该提案的目的是了解发生的结构性变化 在易位之前的展开蛋白质和分子机制 展开的机械。一系列模型的展开途径 将确定并与 溶液中自发展开的途径。机制 展进外化合酶将通过化学或通过化学抑制候选者而确定 突变并衡量对展开的影响。导入的组成部分 将确定有助于发展的机械以及 它们相互相互作用，确定的底物蛋白。假设 机械通过物理拉动机制解散蛋白质将是 测试。 这些信息对于了解蛋白质展开过程是必要的 细胞并了解复杂蛋白机的功能。这 结论也将对理解蛋白质具有广泛的影响 细胞中的易位过程，尤其是关于机制 为蛋白靶向膜提供特异性。有趣的是， 易位和降解共享机制期间的展开过程 特征。最后，该主题与人类疾病直接相关。为了 例如，草种的遗传形式是由于酶错过 从过氧化物酶体到线粒体。由于不需要进口 进入过氧化物酶体，而遗漏的蛋白质含有功能性过氧化物酶体 针对信息，防止展开应纠正排序缺陷。