The Mechanism of Energy Level Sensing in Escherichia coli

大肠杆菌的能级传感机制

• 批准号: 8905286
• 负责人: Kim Lewis
• 金额: --
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-09-15 至 1993-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8905286&HistoricalAwards=false
• 关键词: Mechanism; Energy; Level; Sensing; Escherichia

The energy level of a cell is determined by the state of three interconvertible components: ATP, the proton motive force, and the redox level of the electron transport chain. Oxygen taxis, oxidizable substrate taxis and phototaxis are all behaviors governed by sensing of the energy level. This research will identify the energy-level sensor of E. coli and establish the principal mechanism of sensing. An arcB mutant fails to show O2- taxis and oxidizable substrate (proline) taxis. A cloned arcB locus will be used to identify the sensor by expressing and localizing the arcB product. By comparing cell responses to CN and uncoupler that similarly decrease the pmf, but have different effects on the redox state, it will be found whether a redox chain component or pmf per se are immediately responsible for energy level sensing. Understanding of information transduction will be achieved by isolating pseudorevertants to arcB that will map in a che gene(s). This study bridges two fields of knowledge: metabolic regulation and behavior, since arcB controls both taxis and O2-dependent transcription. It is highly possible that arcB (or a homologous compound) is additionally responsible for other instances of so-called "pmf-dependent" regulation in various bacteria, as well as in mitochondria and chloroplasts. It is of fundamental significance to learn how the bacterial cell senses its own energy level and uses this information to control behavior. A new type of sensor which is substantially different from known sensors will be explored in this study. The principal mechanism of energy level sensing will be elucidated. Since it is possible that mitochondria and chloroplasts "inherited" the energy level sensor from bacteria, this research may provide a model system for studying behavior of higher organisms.

细胞的能量水平是由三个相互转换的组分的状态决定的：ATP、质子动力和电子传递链的氧化还原水平。氧趋向性、可氧化底物趋向性和光趋向性都是由能级感知控制的行为。本研究将对大肠杆菌的能级传感器进行鉴定，并建立其传感的主要机制。arcB突变体不能表现出氧趋向性和可氧化底物（脯氨酸）趋向性。克隆的arcB基因座将通过表达和定位arcB产物来识别传感器。通过比较细胞对CN和解耦剂的反应，它们同样会降低pmf，但对氧化还原状态有不同的影响，将发现是氧化还原链成分还是pmf本身直接负责能量感应。对信息转导的理解将通过分离arcB的伪回复性来实现，这些伪回复性将映射到一个（多个）基因中。这项研究连接了两个知识领域：代谢调节和行为，因为arcB控制着趋动性和o2依赖性转录。极有可能的是，在各种细菌以及线粒体和叶绿体中，arcB（或一种同源化合物）还负责其他所谓的“pmf依赖”调节。了解细菌细胞如何感知自身的能量水平并利用这些信息来控制行为具有重要的意义。本研究将探索一种与已知传感器有本质区别的新型传感器。本文将阐明能级传感的主要机理。由于线粒体和叶绿体可能从细菌那里“遗传”了能量水平传感器，因此本研究可能为研究高等生物的行为提供一个模型系统。