SENSORY TRANSDUCTION IN BACTERIA

大多数细菌趋化的途径都涉及感官的甲基化。 换能器。这个实验室的研究涉及到 鼠伤寒沙门氏菌和大肠杆菌的甲基化非依赖性途径 大肠杆菌对氧气和糖的趋化性(嗜氧性) 磷酸转移酶系统(PTS)。不依赖甲基化的和 甲基化依赖的通路在控制 鞭毛马达的旋转方向。两国之间的相互作用 这些途径以及汇聚点也将被研究。这个 底物抑制转导子甲基化的机制 PTS，以及cGMP在这一现象中的作用将用 行为学、体外转导子甲基化和去甲基化检测，以及 蛋白质化学。有人建议确定通过什么机制 蛋白质甲基酯酶(CHEB)的缺失逆转了这种趋气性反应。 对PTS糖的趋化作用的独特之处在于需要完整的运输系统 作为引诱剂。建议确定必要的组件 对于感觉转导，它们的功能，特别是 适应。初步调查将涉及 活性位点以外的位点上PTS组分的磷酸化。 空气亲和性是由探测质子变化的“原型计”调节的。 并传递一种信号，导致适当的行为 变化。作为迈向长期目标的第一步，识别和 表征好氧系统的组成，大肠杆菌突变体在 将对趋空性进行选择、绘制地图并确定其特征。它的作用机制 对高浓度氧气的排斥反应将是 调查过了。信号传输或信号传输都需要ATP 鞭毛开关。在细胞中加入8-叠氮腺苷可以替代 腺嘌呤在激活趋化作用中的作用。在确认形成后 三磷酸叠氮腺苷，细胞将被照射和分级 鉴定趋化途径的三磷酸腺苷结合成分。 随后，将确定ATP在趋化作用中的作用方式。

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.