Assembly Localiztion and Function of the U3 snRNP

描述（由申请人提供）：大量的细胞代谢致力于产生核糖体，核糖体是负责将mRNA翻译成蛋白质的蛋白质合成的大型核糖核蛋白工厂。核糖体是在一系列内切和外切反应后在核仁中合成的，这些反应将前rRNA加工成18 S、5.8S和25 S rRNA。我的实验室最近纯化和表征了一种新的大RNP，SSU（小亚基）加工体，这是前18 S rRNA加工所需的。虽然我们的工作已经发现了30多个SSU加工体蛋白，但我们假设可能还有其他重要的组分，包括RNA解旋酶和核酸内切酶，它们与SSU加工体一起起作用以使18 S rRNA成熟。此外，关于SSU加工体在pre-rRNA上的组装以及它如何与pre-rRNA转录相关知之甚少。我们的长期目标是了解前rRNA加工，RNA折叠和核糖体组装步骤的核糖体生物合成必不可少的。本申请的目的是揭示不同的方面，包括动态的性质，小核糖体亚基（SSU）的生物发生。中心假设是在前188 rRNA上形成SSU加工体是SSU生物发生的关键部分。我们的工作是有意义的，因为SSU加工体是至关重要的基因表达，因此细胞生长，在所有的真核细胞。在具体目标1，我们将测试的假设，在DExD/H盒RNA解旋酶的保守基序的突变，可以用来更精确地定义它们的功能在SSU生物发生。在目标2中，我们将进一步研究前rRNA转录和SSU加工体成分介导的加工之间的联系。在目标3中，我们将检验由ORFSYOR 004 w和YDR 339 c编码的蛋白质编码前18 SrRNA加工所需的核酸内切酶的假设。在目标4中，我们将测试的假设，有其他非必需基因编码蛋白质参与前18 S rRNA核糖体生物合成。

DESCRIPTION (provided by applicant): A tremendous amount of cellular metabolism is dedicated to producing ribosomes, the large ribonucleoprotein factories of protein synthesis responsible for translating mRNAs into proteins. Ribosomes are synthesized in the nucleolus following a series of endonucleolytic and exonucleolytic reactions that process the pre-rRNA to the 18S, 5.8S and 25S rRNAs. My laboratory has recently purified and characterized a new large RNP, the SSU (small subunit) processome, which is required for pre-18S rRNA processing. While our work has uncovered 30+ of the SSU processome proteins, we hypothesize that there may be other important components, including RNA helicases and endonucleases, that function with the SSU processome to mature the 18S rRNA. In addition, very little is known about the assembly of the SSU processome on the pre-rRNA and how it is related to pre-rRNA transcription. Our long-term goal is to understand the pre-rRNA processing, RNA folding and ribosome assembly steps essential to ribosome biogenesis. The objective of this application is to uncover different aspects, including the dynamic nature, of small ribosomal subunit (SSU) biogenesis. The central hypothesis is that formation of the SSU processome on the pre-188 rRNA is a critical part of SSU biogenesis. Our work is significant because the SSU processome is vital to gene expression, and therefore cell growth, in all eukaryotic cells. In Specific Aim 1, we will test the hypothesis that mutations in conserved motifs in DExD/H box RNA helicases can be used to more precisely define their function in SSU biogenesis. In Aim 2, we will further investigate the link between pre-rRNA transcription and processing mediated by the SSU processome components. In Aim 3, we will test the hypothesis that the proteins encoded by ORFS YOR004w and YDR339c encode endonucleases required for pre-18S rRNA processing. In Aim 4, we will test the hypothesis that there are other non-essential genes encoding proteins involved in pre-18S rRNA ribosome biogenesis.