SENSORY TRANSDUCTION IN BACTERIA

大多数细菌趋化性的途径都涉及甲基化 感官传感器。这个实验室的研究涉及到 鼠伤寒沙门氏菌和沙门氏菌的甲基化非依赖性途径 大肠埃希氏菌对氧气和糖的趋化性 由磷酸转移酶系统(PTS)运输。这个 甲基化非依赖和甲基化依赖途径收敛 在开关之前-它控制 鞭毛马达。目标是从分子上详细描述信号。 这些行为中的处理机制。临时秘书处的趋同 系统和主要的趋化途径将被研究使用基因 用纯化的蛋白质对系统进行分析和重组。一个 将开发敏感的趋化作用分光光度分析方法 在重建研究中使用。具有嗜气性缺陷的突变体 将被选择和鉴定，绘制突变图谱和基因 克隆的。与趋空性基因产物相互作用的成分将是 通过等位基因特异性抑制分析鉴定。建议数 机制将通过重组纯化的成分来确认。 大肠埃希氏菌和鼠伤寒沙门氏菌被高 氧气浓度。反应的生理学将是 被调查，包括抑制或诱导，对氧气的需求 消耗或氧化还原感觉与氧回避的可加性 反应和趋化反应。遗传和生化 将使用与上述类似的调查来确定 回避反应的组成部分和与 趋化途径。活性氧物种或AppppA的可能作用 在调解过程中，将对此进行调查。中国的空气动态化 盐生细菌是唯一一种 甲基化依赖，我们将进一步研究其机制。 这样的回应。

Most pathways for bacterial chemotaxis involve methylation of the sensory transducer. Studies in this laboratory are concerned with methylation-independent pathways in Salmonella typhimurium and Escherichia coli for chemotaxis to oxygen (aerotaxis) and to sugars transported by the phosphotransferase system (PTS). The methylation-independent and the methylation-dependent pathways converge before the switch -that controls the direction of rotation of the flagellar motors. The goal is to describe in molecular detail the signal processing mechanisms in these behaviors. The convergence of the PTS system and the main chemotaxis pathway will be investigated using genetic analysis and reconstitution of the system with purified proteins. A sensitive spectro-photometric assay for chemotaxis will be developed for use in the reconstitution studies. Mutants with a defect in aerotaxis will be selected and characterized, the mutation mapped and the gene cloned. Components interacting with the aerotaxis gene product will be identified by allele-specific suppression analysis. The proposed mechanism will be confirmed by reconstitution with purified components. E. coli and S. typhimurium are repelled by high concentrations of oxygen. The physiology of the response will be investigated, including repression or induction, a requirement for oxygen consumption or redox sensing and the additivity of the oxygen-avoidance response and chemotactic responses. Genetic and biochemical investigations similar to those described above will be used to determine components of the avoidance response and the site of convergence with the chemotaxis pathway. A possible role of reactive oxygen species or AppppA in mediating the response will be investigated. Aerotaxis in Halobacterium halobium is the only aerotaxis that is methylation-dependent and we will further investigate the mechanism of this response.