Regulation of Stationary Phase in Escherichia coli

大肠杆菌固定相的调节

• 批准号: 7010626
• 负责人: Thomas J. Silhavy
• 金额: $ 26.8万
• 依托单位: PRINCETON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-02-01 至 2007-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7010626
• 关键词: Escherichia coli; bacterial proteins; biological signal transduction; carbon; deficient growth media; dietary constituent; microorganism culture; microorganism growth; microorganism metabolism; nitrogen; phosphorus; protein structure function

DESCRIPTION (provided by applicant): Growth of Escherichia coli ceases when nutrients are depleted or when secreted waste products accumulate to high levels. Under these conditions the bacteria initiate a complex developmental plan to allow extended survival. In the lab this stationary phase of the bacterial life cycle can be achieved by starvation for a single essential nutrient such as a carbon source, phosphate, or nitrogen in the form of ammonia. Implementation of the stationary phase developmental plan requires the alternate sigma factor RpoS.Previously we have identified an orphan response regulator SprE (also known as RssB or MviA). In rapidly growing cells, SprE directs RpoS for destruction by the ATP-dependent protease CIpP/X, thus maintaining this sigma factor at low levels. SprE activity is inhibited when cells are starved for carbon, and RpoS levels quickly rise. We have also shown that RpoS stimulates sprE expression. Paradoxically this regulatory feedback loop results in high levels of SprE in stationary phase cells when the protein is presumably inactive. Using a combination of genetics and biochemistry we will define the signal transduction pathway that controls SprE activity, and we will probe the functional significance or this regulatory feedback loop. We will also determine the signal transduction mechanisms responsible for the development of stationary phase when cells are starved for phosphate or ammonia, and we will determine how cells integrate the conflicting signals that can arise when cells are starved for only one of these elements. Stationary phase raises several questions of fundamental importance. Cells sense and respond to impending starvation. How do they know they are about to deplete the medium of one essential nutrient when all other essential nutrients are abundant? How are conflicting signals integrated? Finally, since RpoS is important for the pathogenesis of several bacteria, an understanding of this complex signal transduction network may reveal chinks in the armor of these pathogens.

性状（由申请方提供）：当营养素耗尽或分泌的废物积累到高水平时，大肠杆菌停止生长。在这些条件下，细菌启动一个复杂的发育计划，以延长生存期。在实验室中，细菌生命周期的这个稳定期可以通过饥饿单一必需营养素来实现，例如碳源，磷酸盐或氨形式的氮。稳定期开发计划的实施需要替代sigma因子RpoS。以前，我们已经确定了孤儿反应调节剂SprE（也称为RssB或MviA）。在快速生长的细胞中，SprE指导RpoS被ATP依赖性蛋白酶ClpP/X破坏，从而将这种sigma因子维持在低水平。当细胞缺乏碳时，SprE活性受到抑制，RpoS水平迅速上升。我们还表明，RpoS刺激sprE表达。有趣的是，当蛋白质被推测为无活性时，这种调节反馈回路导致稳定期细胞中高水平的SprE。使用遗传学和生物化学的组合，我们将定义控制SprE活性的信号转导途径，我们将探索这种调节反馈回路的功能意义。我们还将确定当细胞缺乏磷酸盐或氨时，负责稳定期发展的信号转导机制，并且我们将确定细胞如何整合当细胞仅缺乏这些元素之一时可能出现的冲突信号。 固定相提出了几个基本的重要问题。细胞对即将到来的饥饿感和反应。当其他必需营养素都很丰富的时候，它们怎么知道它们即将耗尽培养基中的一种必需营养素呢？ 如何整合相互冲突的信号？ 最后，由于RpoS对多种细菌的发病机制很重要，因此对这种复杂信号传导网络的了解可能会揭示这些病原体盔甲上的裂缝。