Eukaryotic Ribosome Assembly

项目摘要 核糖体负责细胞中所有蛋白质以各种形式快速准确地产生。 地球上的生命。这些分子机器进行忠实翻译的能力取决于它们的复杂性。 允许与配体动态相互作用的结构。真核细胞中成熟的核糖体由 两部分，大的60 S亚基合成细胞中所有的蛋白质，小的40 S亚基， 解码mRNA。真核生物核糖体的产生涉及200多种辅助因子， 协调核糖体RNA的复杂加工和折叠以及核糖体蛋白的组装。 考虑到核糖体结构和功能的复杂性及其在解码我们的遗传密码中的关键作用， 信息，确保它们的正确组装是细胞的一项必要但艰巨的任务。最近， 人们的兴趣集中在核糖体生物发生途径中的质量控制机制上。这项建议 重点放在两个不同的主题内核糖体组装;（1）机制，评估结构和 新组装的60 S亚基的功能完整性和（2）从早期90 S前核糖体的过渡 40 S前体的前体。 关于结构和功能完整性的评估，本建议涉及三个相关问题， 问题：一.新产生的亚单位是如何评估其功能的？二.缺陷亚基的命运如何？三. 许可有缺陷的核糖体的后果是什么？在人类中，这些过程中的缺陷导致 各种疾病，包括T细胞急性淋巴细胞白血病和Shwachman-Diamond综合征。 核糖体小亚基的组装涉及90 S 颗粒，一个大的蛋白质-RNA复合物，支架上的U3-snoRNA。但是，U3的存在是相互的。 与小亚基RNA的最终折叠结构不相容，一旦转录， RNA是完整的，90 S颗粒已经完全组装。从90年代到40年代前的过渡很差 明白我们认为，U3被RNA解旋酶Dhr 1取代是驱动U3的主要事件。 90 S向40 S前粒子的转变。我们将确定Dhr 1的活性是如何调节的， 确保U3的及时发布。

Project Summary Ribosomes are responsible for the rapid and accurate production of all proteins in cells in all forms of life on earth. The ability of these molecular machines to carry out faithful translation depends on their complex structure that allows dynamic interaction with ligands. The mature ribosome in eukaryotic cells is composed of two parts, the large 60S subunit that synthesizes all the proteins in a cell and the small 40S subunit that decodes mRNA. The production of a eukaryotic ribosome involves over 200 accessory factors which orchestrate the intricate processing and folding of the ribosomal RNA and assembly of the ribosomal proteins. Considering the complexity of ribosome structure and function and its critical role in decoding our genetic information, ensuring their correct assembly is a necessary but daunting task for cells. Lately, considerable interest has been focused on mechanisms of quality control in the ribosome biogenesis pathway. This proposal focuses on two distinct topics within ribosome assembly; (1) the mechanisms for assessing the structural and functional integrity of the newly assembled 60S subunit and (2) the transition from the early 90S pre-ribosomal precursor to the pre-40S precursor. With respect to assessment of structural and functional integrity, this proposal addresses three related questions: I. How are newly minted subunits assessed for function? II. What is the fate of defective subunits? III. What is the consequence of licensing defective ribosomes? In humans, defects in these processes lead to various diseases, including T-cell acute lymphoblastic leukemia and Shwachman-Diamond syndrome. Assembly of the small ribosomal subunit involves stepwise cotranscriptional assembly of the 90S particle, a large protein-RNA complex, scaffolded on U3-snoRNA. However, the presence of U3 is mutually incompatible with the final folded structure of small subunit RNA and must be removed once transcription of the RNA is complete and the 90S particle has fully assembled. The transition from the 90S to pre-40S is poorly understood. We propose that the displacement of U3 by the RNA helicase Dhr1 is a primary event that drives the transition of the 90S into the pre-40S particle. We will determine how the activity of Dhr1 is regulated to ensure the timely release of U3.