Regulation of Stationary Phase in Escherichia coli

大肠杆菌固定相的调节

• 批准号: 6573130
• 负责人: Thomas J. Silhavy
• 金额: $ 26.93万
• 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/6573130
• 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）：大肠杆菌的生长在耗尽养分或分泌废物时停止。在这些条件下，细菌启动了复杂的发展计划，以扩展生存。在实验室中，可以通过饥饿来实现这种细菌生命周期的固定阶段，例如单个必需营养素，例如碳源，磷酸盐或氮的形式。固定阶段发展计划的实施需要替代的Sigma因子RPOS。我们已经确定了孤儿响应调节器SPRE（也称为RSSB或MVIA）。在快速生长的细胞中，SPRE指导RPOS因ATP依赖性蛋白酶CIPP/X而破坏，从而将该Sigma因子保持在低水平。当细胞因碳而饥饿时，SPRE活性会抑制，RPOS水平迅速升高。我们还表明，RPO刺激SPRE表达。矛盾的是，当蛋白质可能不活跃时，这种调节反馈回路会导致固定相细胞的高水平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，我们将探测功能意义或该调节反馈回路。我们还将确定当细胞饥饿的磷酸盐或氨的饥饿时，负责固定相的发展的信号转导机制，我们将确定细胞如何整合仅在这些元素之一饥饿的细胞时会产生的冲突信号。 固定阶段提出了几个基本重要性的问题。细胞感知并应对即将发生的饥饿。他们怎么知道，当所有其他必需营养素丰富时，他们即将耗尽一种必需营养素的培养基？ 冲突的信号如何整合？ 最后，由于RPOS对于几种细菌的发病机理很重要，因此对这种复杂信号转导网络的理解可能会揭示这些病原体的装甲中的缝隙。