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.

描述（由申请人提供）：当营养物质耗尽或分泌的废物积累到高水平时，大肠杆菌的生长停止。在这些条件下，细菌启动复杂的发育计划以延长生存时间。在实验室中，细菌生命周期的这个稳定阶段可以通过单一必需营养素（例如碳源、磷酸盐或氨形式的氮）的饥饿来实现。稳定期发育计划的实施需要替代西格玛因子RpoS。之前我们已经确定了孤儿反应调节因子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 CIpP/X 破坏，从而将该 σ 因子维持在较低水平。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。矛盾的是，当该蛋白可能处于非活性状态时，这种调节反馈回路会导致稳定期细胞中 SprE 水平升高。结合遗传学和生物化学，我们将定义控制 SprE 活性的信号转导途径，并且我们将探讨其功能意义或这种调节反馈循环。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。 固定相提出了几个具有根本重要性的问题。细胞感知即将到来的饥饿并做出反应。当所有其他必需营养素都丰富时，它们如何知道自己即将耗尽一种必需营养素的培养基？ 如何整合冲突信号？ 最后，由于 RpoS 对于多种细菌的发病机制很重要，因此了解这种复杂的信号转导网络可能会揭示这些病原体盔甲中的漏洞。