SENSORY TRANSDUCTION IN BACTERIA

细菌趋化性的大多数途径都涉及到感觉区的甲基化。 传感器 本实验室的研究涉及 鼠伤寒沙门氏菌和大肠杆菌中的甲基化非依赖性途径 大肠杆菌的趋化性，以氧（嗜氧性）和糖运输的 磷酸转移酶系统（PTS）。 甲基化不依赖性和 依赖甲基化的通路在控制细胞内的 鞭毛马达的旋转方向。 之间的相互作用 将研究这些途径以及汇合点。 的 通过这种机制，转导子甲基化被 PTS，cGMP在这种现象中的作用将使用 行为，体外测定转导子甲基化和去甲基化，以及 蛋白质化学 建议确定以下机制： 蛋白质甲基酯酶（切布）的缺失逆转了趋氧性反应。 对PTS糖的趋化性是独特的，需要一个完整的运输系统 引诱剂 建议确定必要的组成部分， 对于感觉传导，它们的功能，特别是 适应 初步调查将涉及 PTS组分在活性位点以外的位点磷酸化。 趋气性是由一个“质子计”来调节的，它可以检测质子的变化 动机和传递信号，导致适当的行为 变化 作为实现确定和 描述了趋空系统的组成部分，E.大肠杆菌突变体 需氧性将被选择、绘制和表征。 的机理 对高浓度氧气的排斥反应将是 研究了 ATP是信号传输所必需的， 鞭毛开关 8-加入到细胞中的叠氮腺苷可以替代 腺嘌呤激活趋化性。 在确认形成 叠氮腺苷三磷酸，细胞将被照射和分级 以确定趋化途径的ATP结合成分。 随后，将确定ATP在趋化性中的作用方式。

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 interaction between these pathways and also the point of convergence will be investigated. The mechanism by which transducer methylation is depressed by substrates of the PTS, and the role of cGMP in this phenomenon will be studied using behavior, in vitro assays of transducer methylation and demethylation, and protein chemistry. It is proposed to determine the mechanism by which deletion of protein methylesterase (CheB) inverts the aerotactic response. Chemotaxis to PTS sugars is unique in requiring an intact transport system for the attractant. It is proposed to identify the components necessary for sensory transduction, their function, and particularly the mechanism of adaption. Initial investigations will be concerned with the phosphorylatio of PTS components at sites other than the active site. Aerotaxis is mediated by a "protometer" that detects changes in the proton motive force and transmits a signal that results in appropriate behavioral change. As a first step toward the long range goal of identifying and characterizing the components of the aerotactic system, E. coli mutants in aerotaxis wilal be selected, mapped and characterized. The mechanism of the repellent response to high concentrations of oxygen will be investigated. ATP is required for either signal transmission or the flagella switch. 8-Azidoadenosine added to the cells can substitute for adenine in activating chemotaxis. After confirming the formation of azidoadenosine triphosphate, the cells will be irradiated and fractionated to identify ATP-binding components of the chemotactic pathway. Subsequently, the mode of action of ATP in chemotaxis will be determined.