Genome-wide Function and Substrate Recognition of the Chaperone Prefoldin

描述（由申请人提供）：伴侣蛋白有助于许多蛋白质的正确折叠并防止蛋白质聚集，蛋白质聚集越来越多地被认为是人类疾病如阿尔茨海默氏症的致病机制。前折叠蛋白是一种蛋白伴侣，已知其在新翻译的肌动蛋白和微管蛋白的折叠中起作用。我们希望了解prefoldin的整体细胞功能，并确定它如何识别其底物。对肌动蛋白和微管蛋白的前折叠蛋白功能的研究表明，它结合新生肽并将其隔离，同时将其递送至TRiC/CCT伴侣蛋白。前折叠蛋白有六个同源亚基，每个亚基都有一个长的卷曲螺旋突起。某些亚基的尖端与肌动蛋白和微管蛋白结合，并且这些底物中的每一个中的限定残基对于这种相互作用是必需的。因此，前折叠蛋白结合是特异性的，并且可能涉及不同亚基对不同靶标的组合结合。我们的具体目标是：1）确定prefoldin的细胞功能。我们将使用全基因组测量与分子伴侣突变的遗传相互作用，以确定哪些过程受到前折叠蛋白的影响。2)鉴定新的前折叠蛋白靶标并测试TRiC/CCT依赖性。我们将发现其他蛋白质依赖于prefoldin通过使用特征模式的上位突变之间的伴侣和它的目标。然后，我们将测试候选底物与分子伴侣的直接物理相互作用，并确定分子伴侣功能的丧失是否会影响它们在体内的折叠。3)了解前折叠蛋白如何结合其各种不相关的底物。我们将使用缺失和点突变的基础上解决结构的前折叠蛋白，以确定哪些区域的前折叠蛋白所需的特定目标蛋白。我们将使用基因测试前折叠蛋白功能以及生化测量前折叠蛋白结合。蛋白质聚集在包括阿尔茨海默氏症在内的许多人类疾病中起着重要作用。蛋白质伴侣与新产生的蛋白质结合，帮助它们折叠，同时防止它们聚集。我们想知道伴侣蛋白前折叠蛋白如何结合特定的靶蛋白，以及它在正常细胞功能中的作用。

DESCRIPTION (provided by applicant): Chaperones assist in the proper folding of many proteins and protect against protein aggregation, which is increasingly recognized as a pathogenic mechanism in human diseases such as Alzheimer's. Prefoldin is a protein chaperone that is known to play a role in the folding of newly-translated actin and tubulin. We wish to understand the overall cellular function of prefoldin and determine how it recognizes its substrates. Studies of prefoldin function on actin and tubulin suggest that it binds nascent peptides and sequesters them while delivering them to the TRiC/CCT chaperonin. Prefoldin has six homologous subunits, each of which has a long, coiled-coil projection. The tips of certain subunits bind to actin and tubulin, and defined residues in each of these substrates are necessary for this interaction. Thus, prefoldin binding is specific ' and may involve a combinatorial binding of different subunits for different targets. Our specific aims are: 1) Determine the cellular functions of prefoldin. We will use whole-genome measurements of genetic interactions with chaperone mutations to determine which processes are affected by prefoldin. 2) Identify new prefoldin targets and test for TRiC/CCT dependence. We will find additional proteins that depend on prefoldin by using the characteristic pattern of epistasis between mutations in a chaperone and its target. We will then test candidate substrates for direct physical interaction with the chaperone and determine whether loss of chaperone function affects their folding in vivo. 3) Understand how prefoldin binds its various, unrelated substrates. We will use deletions and point mutants based on the solved structure of prefoldin to determine which regions of prefoldin are required by specific target proteins. We will use genetic tests for prefoldin function as well as biochemical measurements of prefoldin binding. Protein aggregation plays a major role in many human diseases, including Alzheimer's. Protein chaperones bind to newly-produced proteins and help them to fold while preventing them from aggregating. We want to know how the chaperone prefoldin binds specific target proteins and what role this has in normal cell function.