Ribosomal Genes of Yeast and Their Regulation

描述（由申请人提供）：分子机器，如核糖体或核孔，对细胞的顺利运作至关重要。这一建议涉及两个问题，这两个问题对任何分子机器的构建都很重要，但对核糖体来说尤为重要：(A)如何提供每种组成分子的适量，以及(B)如何对最终产品进行质量控制，并处理那些不符合标准的复合物。对于酿酒酵母来说，核糖体的构建消耗了其经济的很大一部分；有效的核糖体合成对其适应性至关重要。对哺乳动物生物体来说，核糖体的构建被密切监测，作为衡量细胞健康状况的一项指标；异常核糖体合成导致细胞周期阻滞或细胞死亡，并与几种疾病状态有关。我们已经确定了一个由四种蛋白质组成的复合物，它似乎是耦合核糖体RNA和核糖体蛋白质合成的关键因素。我们建议进行实验来证实这种联系，并试图确定这种耦合的生化和生理基础。我们已经开发了一个系统，其中有一个主要的和慢性的，但不是致命的，各种类型的异常前核糖体的积累。我们将在遗传和生化实验中使用该系统来发现这些异常前核糖体的识别和降解背后的基因和生物化学。初步数据表明，泛素-蛋白酶体系统的几个不同成员以及trump -外泌体复合体的一些成员参与了一组相当不寻常的成员。这些实验的成功将为细胞如何在分子机器的组成部分的生产中保持平衡，以及细胞如何处理异常核糖体而不给自身带来风险提供新的见解。

DESCRIPTION (provided by applicant): Molecular machines, such as the ribosome or the nuclear pore, are of critical importance for the smooth functioning of the cell. This proposal deals with two issues that are important for the construction of ANY molecular machine, but are particularly acute for the ribosome: (A) How to supply the right amount of each of the constituent molecules, and (B) How to exert quality control over the final product and dispose of those complexes that do not meet standards. For S. cerevisiae construction of the ribosome consumes a major portion of its economy; effective ribosome synthesis is critical for its fitness. For mammalian organisms the construction of the ribosome is closely monitored as a measure of the cell's health; aberrant ribosome synthesis leads to cell cycle arrest or cell death, and has been implicated in several disease states. We have identified a complex of four proteins that appears to be a key factor in coupling the synthesis of ribosomal RNA and ribosomal proteins. We are proposing experiments to confirm this connection and to try to identify the biochemical and physiological basis for this coupling. We have developed a system in which there is a major and chronic, but not lethal, accumulation of aberrant pre-ribosomes of various types. We will use this system in both genetic and biochemical experiments to discover the genes and the biochemistry behind the identification and degradation of such aberrant pre-ribosomes. Preliminary data suggests the involvement of a rather unusual set of several distinct members of the ubiquitin-proteasome system, as well as some members of the TRAMP-exosome complex. The success of these experiments will provide new insight into how a cell can maintain BALANCE in the production of the components of a molecular machine, as well as how the cell can dispose of aberrant ribosomes at least risk to itself.