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，这两个问题对于任何分子机器的构建都很重要，但对于核糖体来说尤其尖锐：（A）如何提供每个组成分子的正确数量，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。对于鼠伤寒沙门氏在酿酒酵母中，核糖体的构建消耗了其经济的主要部分;有效的核糖体合成对其适应性至关重要。对于哺乳动物生物体，核糖体的构建被密切监测作为细胞健康的量度;异常的核糖体合成导致细胞周期停滞或细胞死亡，并且已经涉及几种疾病状态。我们已经确定了一个复杂的四个蛋白质，似乎是一个关键因素耦合的核糖体RNA和核糖体蛋白质的合成。我们正在提出实验来证实这种联系，并试图确定这种耦合的生物化学和生理学基础。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。我们将在遗传和生物化学实验中使用该系统，以发现识别和降解这种异常前核糖体背后的基因和生物化学。初步数据表明，参与了一个相当不寻常的一组几个不同的成员的泛素-蛋白酶体系统，以及一些成员的TRAMP-外泌体复合物。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提供新的见解，以及细胞如何处理异常的核糖体，至少对自己有风险。

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.