Magariyama Y, Yamaguchi S, Aizawa S
ERATO, Research and Development Corporation of Japan, Ibaraki.
J Bacteriol. 1990 Aug;172(8):4359-69. doi: 10.1128/jb.172.8.4359-4369.1990.
At the interface between the sensory transduction system and the flagellar motor system of Salmonella typhimurium, the switch complex plays an important role in both sensory transduction and energy transduction. To examine the function of the switch complex, we isolated from 10 cheY mutants 500 pseudorevertants with a suppressor mutation in one of the three genes (fliG, fliM, and fliN) encoding the switch complex. Detailed mapping revealed that these suppressor mutations were localized to several segments of each switch gene, suggesting localization of functional sites on the switch complex. These switch mutations were introduced into the wild-type background and into a chemotaxis deletion background. Behavior of the pseudorevertants and their derivatives (1,500 strains in all) was observed by light microscopy. In the chemotaxis deletion background, about 70% of the switch mutants showed smooth swimming and the rest showed more or less tumbly swimming. There was some correlation between the mutational sites and the swimming patterns in the chemotaxis deletion background, suggesting that there is segregation of functional sites on the switch complex. The interaction of the switch complex with the chemotaxis protein, CheY, and the stochastic nature of switching in the absence of CheY are discussed.
在鼠伤寒沙门氏菌的感觉转导系统与鞭毛运动系统的界面处，开关复合体在感觉转导和能量转导中均发挥着重要作用。为了研究开关复合体的功能，我们从10个cheY突变体中分离出了500个假回复体，这些假回复体在编码开关复合体的三个基因（fliG、fliM和fliN）之一中带有一个抑制突变。详细的定位分析表明，这些抑制突变定位于每个开关基因的几个区段，这表明开关复合体上存在功能位点。将这些开关突变引入野生型背景和趋化性缺失背景中。通过光学显微镜观察了假回复体及其衍生物（总共1500个菌株）的行为。在趋化性缺失背景中，约70%的开关突变体表现出平滑游动，其余的则或多或少表现出翻滚游动。在趋化性缺失背景中，突变位点与游动模式之间存在一定的相关性，这表明开关复合体上存在功能位点的分离。文中还讨论了开关复合体与趋化性蛋白CheY的相互作用以及在没有CheY时开关的随机性质。
