Mechanism, Activation, and Control of rRNA Transcription

描述(由申请人提供)：负责制造蛋白质(如核糖体RNA、核糖体蛋白、翻译因子和tRNA)的机制对所有生物体的生长和发育都是至关重要的。至少五十年来，调节翻译机器的合成以响应细胞的营养状态一直是微生物生理学研究的中心问题。最近，对大肠杆菌中rRNA转录机制的了解也变得清晰起来，这可以为理解转录机制提供基本的见解。我们准备解决一些核心问题，这些问题对于我们理解一般的转录机制和我们对不同调控系统如何协同工作的理解都是至关重要的。提案中涉及的问题按任意顺序分为四个具体目标。在第一个目标中，我们将研究RNA聚合酶α亚基的C末端结构域在细菌启动子识别中的一个意想不到的作用。在第二个目标中，我们建议确定RRN转录因子FIS如何增加来自-35元件上游的转录，以及它如何影响转录机制中的不同步骤。在第三个目标中，我们建议确定不同的机制何时有助于调节RRn P1和RRn P2启动子以响应营养条件的变化，以及这如何维持内稳态。同样作为这一目标的一部分，我们将确定控制rRNA转录的关键决定因素-开放复合体的寿命-的分子相互作用，我们将研究一种新的、以前未知的rRNA转录调控因子，我们将开始tRNA启动子的基因组研究。在第四个具体目标中，我们将使用细胞生物学的工具来确定rRNA操纵子在细菌类核中的位置。

DESCRIPTION (provided by applicant): The machinery responsible for making proteins (e.g. ribosomal RNA, ribosomal proteins, translation factors, and tRNAs) is central to growth and development of all organisms. The regulation of the synthesis of the translation machinery in response to the nutritional state of the cell has been a central issue in the study of microbial physiology for at least fifty years. More recently, it has also become clear that an understanding of the mechanisms responsible for rRNA transcription in Escherichia coli can provide fundamental insights into understanding mechanisms of transcription in general. We are poised to address questions central to our understanding of general transcription mechanisms and to our understanding of how different regulatory systems work together. The questions addressed in the proposal are divided into four specific aims in arbitrary order. In the first aim, we will study an unanticipated role of the C-terminal domain of the alpha subunit of RNA polymerase in bacterial promoter recognition. In the second aim, we propose to determine how the rrn transcription factor Fis increases transcription from sites far upstream of the -35 element and how it affects different steps in the transcription mechanism. In the third aim, we propose to determine when different mechanisms contribute to regulation of the rrn P1 and rrn P2 promoters in response to changing nutritional conditions and how this maintains homeostasis. Also as part of this aim, we will determine the molecular interactions responsible for a key determinant in the control of rRNA transcription, the lifetime of the open complex, we will examine a new, previously unrecognized regulator of rRNA transcription, and we will begin a genomic study of tRNA promoters. In the fourth specific aim, we will use the tools of cell biology to determine the locations of rRNA operons in the bacterial nucleoid.