Elucidating the regulation of Rsp5 a paradigm for the Nedd4-family of ubiquitin ligase proteins

所有的细胞都必须有有效的机制来识别和去除不需要的或受损的蛋白质。不能去除受损的蛋白质对生物体来说可能是灾难性的，许多癌症和其他疾病通常是无法降解特定蛋白质的结果。真核细胞用来去除不需要的蛋白质的一种方法是用一种叫做泛素的小蛋白质标记它们。泛素的加入作为一个信号，将标记的蛋白质发送到细胞的“垃圾箱”（降解复合物或隔室），在那里不需要的蛋白质可以被分解和回收。泛素是一个非常灵活的信号，因为它的添加，取决于它附着到另一个蛋白质的位点和方式，可以导致除了破坏以外的结果，如酶激活或导致蛋白质从细胞中的一个地方移动到另一个地方。因此，了解泛素是如何附着在其他蛋白质上的，以及这个过程是如何控制的，对于理解许多不同的生物过程至关重要。泛素连接酶是添加泛素所必需的一组酶。泛素连接酶是重要的，因为在添加泛素的过程中，它们结合靶蛋白并控制整个途径的特异性。要了解泛素途径，你必须了解泛素连接酶。这项计划的目的是研究在面包酵母（酿酒酵母）中发现的一种名为“Rsp 5”的泛素连接酶。Rsp5是一种重要的酶，参与控制酵母细胞内多个位置的许多不同细胞过程。与Rsp5相关的一个明显的问题是，如何调节在不同位置具有多个靶点的酶？本提案中描述的实验旨在测试酵母细胞含有多种蛋白质复合物的假设，其中Rsp5是核心组分，这就是Rsp5活性在细胞不同部分中的控制方式。了解Rsp5很重要，因为在其他生物体中也发现了类似的酶，包括人类，其中已经鉴定出9种与Rsp5结构相似的蛋白质。像Rsp5一样，这种酶家族（称为“Nedd4”家族）调节着大量不同的细胞过程，其中许多与癌症和其他严重的人类疾病有关。通过在酵母中对Rsp5进行实验，这是简单且易于生长的，希望我们可以更好地了解Nedd4家族的所有成员，这最终可能导致开发新的人类疾病治疗方法。

All cells must have efficient mechanisms for identifying and removing unwanted or damaged proteins. The failure to remove a damaged protein can be catastrophic to an organism and many cancers and other diseases are often the result of an inability to degrade a particular protein. One method used by eukaryotic cells to remove unwanted proteins is to label them with a small protein called ubiquitin. The addition of ubiquitin acts as a signal that sends the tagged protein to a cellular 'dustbin' (either a degradatory complex or compartment) where the unwanted protein can be broken-down and recycled. Ubiquitin is a remarkably flexible signal since its addition, depending upon the site and the way in which it attached to another protein, can lead to outcomes other than destruction such as enzyme activation or causing the protein to move from one place in the cell to another. Understanding how ubiquitin is attached to other proteins and how this process is controlled is therefore vital to understanding many different biological processes. One group of enzymes that are essential for the addition of ubiquitin are ubiqutin ligases. Ubiquitin ligases are important because during the addition of ubiquitin they bind the target protein and control the specificity of the whole pathway. To understand the ubiquitin pathway you must therefore understand ubiquitin ligase enzymes. The aim of this proposal is to investigate a ubiqutin ligase called 'Rsp5' found in Baker's yeast (Saccharomyces cerevisiae). Rsp5 is an important enzyme involved in controlling many different cellular processes in multiple locations within the yeast cell. One obvious question relating to Rsp5 is how do you regulate an enzyme with multiple targets in different places? The experiments described in this proposal are designed to test the hypothesis that yeast cells contain multiple protein complexes of which Rsp5 is the core component and that this is how Rsp5 activity is controlled in different parts of the cell. Understanding Rsp5 is important because similar enzymes are found in other organisms, including humans where nine proteins similar in structure to Rsp5 have been identified. Like Rsp5, this family of enzymes (called the 'Nedd4'-family) regulates a huge number of different cellular processes, many of which are linked with cancers and other serious human diseases. By performing experiments on Rsp5 in yeast, which is simple and easy to grow, it is hoped that we may better understand all members of the Nedd4-family, which ultimately may lead to the development of new treatments for human diseases.