REGULATION AND FUNCTION OF THE YEAST HEAT SHOCK RESPONSE

蛋白质必须正确地折叠成一个确定的三维结构才能正常发挥作用。 几种人类疾病，包括克雅氏病和囊性纤维化，可以被认为是蛋白质 折叠疾病是因为蛋白质不能在其适当的细胞室中实现活性构象。 在拥挤的细胞环境中，新翻译的蛋白质容易聚集和不产生。 由于暴露在水环境中的疏水残基而导致的过早折叠 通常被隔离在折叠的蛋白质中。分子伴侣是蛋白质的极佳候选者 结合并保护新生的链不受有问题的相互作用的影响，因为它们是瞬变的 与疏水多肽片段的相互作用。在体内和体外的各种系统中收集的数据， 指出一条蛋白质折叠的途径(S)，从蛋白质在核糖体上形成新生链到它们 要么正确折叠，要么降解。分子伴侣在这些过程中扮演着重要的角色。 本提案中描述的实验的重点是确定Hsp70(热休克)的功能 Protein 70K)和Hsp40作为分子伴侣的研究 作为一个模范系统。更具体地说，重点是分子伴侣在早期事件中的作用。 核糖体上的蛋白质折叠。酿酒酵母的胞浆含有两类丰富的、功能丰富的 不同的Hsp70(SSA和SSB蛋白)和3个Hsp40(SIS1、Zuol和Ydjl)。在这些监护人中，SSB， SISL和ZUOL与翻译核糖体有关，暗示在蛋白质生命的早期发挥作用。使用 结合遗传学和生物化学方法，我们将分析SSB、ZUOL和SISL在 翻译和蛋白质折叠的早期步骤。 众所周知，Hsp70和Hsp40作为伴侣协同发挥作用。然而，功能性的 他们之间的关系还没有被很好地理解。我们的目标是了解它们之间的功能关系 与核糖体相关的两个Hsp40(SIS1和Zuol)和一个Hsp70(SSB)。更多 具体地说，我们将通过遗传和生化实验来确定这两个Dna Js是否在功能上 并与SSB进行身体上的互动。此外，我们还将确定一个新生链条的相互作用顺序 核糖体相关的伴侣蛋白。

Proteins must fold correctly into a defined three-dimensional structure in order to properly function. Several human diseases, includingCreutzfeldt-Jacob disease and cystic fibrosis, can be considered protein folding diseases because proteins fail to achieve active conformations in their proper cellular compartment. Within the crowded cellular milieu, newly translated proteins are prone to aggregation and nonproductive premature folding because of the exposure to the aqueous environment of hydrophobic residues which are normally sequestered within the folded protein. Molecular chaperones are excellent candidates for proteins which bind to and protect nascent chains from problematic interactions because of the nature of theirtransient interactions with hydrophobic polypeptide segments. Data collected in a variety of systems, in vivo and in vitro, indicate a pathway(s) of protein folding from the time proteins are nascent chains on ribosomes until they are either properly folded or degraded. Molecular chaperones play important roles in these processes. The focus of experiments described in this proposal is to determine the function of Hsp70 (heat shock protein 70K) and Hsp40 as molecular chaperones chaperone using the budding yeast Saccharomyces cerevisiae as a model system. More specifically, the focus is on the role of molecular chaperones during the early events of protein folding on the ribosome. The cytosol of S. cerevisiae contains two classes of abundant, functionally distinct Hsp70s (SSA and SSB proteins) and three Hsp40s (Sisl, Zuol and Ydjl). Of these chaperones, Ssb, Sisl and Zuol associate with translating ribosomes, suggesting a role early in the life of a protein. Using a combination of genetic and biochemical approaches we will analyze the function of Ssb, Zuol and Sisl in translation and early steps of protein folding. Hsp70s and Hsp40s are known to function cooperatively as chaperones. However, the functional relationship between them is not well understood. Our goal is to understand the functional relationship between the two Hsp40s (Sisl and Zuol) and one Hsp70 (Ssb) which are associated with the ribosome. More specifically, we will ascertain through genetic and biochemical experiments whether these two DnaJs functionally and physically interact with Ssb. In addition, we will determine the sequence of interactions of a nascent chain with the ribosome-associated chaperones.