SENSORY TRANSDUCTION IN BACTERIAL CHEMOTAXIS

游动细菌拥有一种刺激反应系统，在该系统中，输入是 引诱剂或驱避剂的局部浓度，其输出为 细胞的运动。众所周知，一些化学物质，例如糖和 氨基酸，是由特定的受体感知的，受体的变化 占用导致鞭毛旋转偏向的改变(概率 鞭毛逆时针旋转)，但 连接到鞭毛上的受体仍然不清楚。我们将继续 我们通过考察自转运动来研究这个系统的生理 大肠杆菌系留细胞在阶跃和脉冲作用下的行为 刺激物。从含有以下成分的基因工程菌株的反应中 修饰的TAR(天冬氨酸受体)和TSR(丝氨酸受体)蛋白 希望了解有关受体占用的信息是如何跨越 细胞质膜和不同受体类别如何相互作用。从 不同刺激条件下丝状细胞对鞭毛标志物的反应 点的长度，我们将确定它们的物理属性 将信息从受体传递到鞭毛的物质。我们 应该能够确定它的扩散系数和大小。通过 追踪和捆绑来自同一培养物的细胞并比较它们的 游泳和旋转行为，我们希望了解更多关于 同一细胞内不同鞭毛的同步化。这部作品 补充了在遗传学和生化方面在其他方面的研究 实验室。长远的目标是在分子水平上理解 涉及感受器功能和感觉的基本过程水平 转导。

Motile bacteria possess a stimulus-response system in which the input is the local concentration of an attractant or repellent and the output is the motion of the cell. It is known that some chemicals, e.g., sugars and amino acids, are sensed by specific receptors and that changes in receptor occupancy lead to changes in flagellar rotational bias (the probability that the flagella spin counterclockwise), but the way in which the receptors are coupled to the flagella remains obscure. We will continue our studies of the physiology of this system by examining the rotational behavior of tethered cells of Escherichia coli exposed to step and impulse stimuli. From responses of genetically engineered strains containing modified tar (aspartate receptor) and tsr (serine receptor) proteins, we expect to learn how information about receptor occupancy crosses the cytoplasmic membrane and how different receptor classes interact. From the responses of flagellar markers on filamentous cells stimulated at different points along their length, we will determine the physical properties of the substance that carries information from the receptors to the flagella. We should be able to determine its diffusion coefficient and its size. By tracking and tethering cells from the same culture and comparing their swimming and rotational behavior, we expect to learn more about synchronization of different flagella in the same cell. This work complements that on genetics and biochemistry pursued in other laboratories. The long-range goal is an understanding at the molecular level of basic processes involved in receptor function and sensory transduction.