Parkinson J S, Parker S R
Proc Natl Acad Sci U S A. 1979 May;76(5):2390-4. doi: 10.1073/pnas.76.5.2390.
Previous work has shown that the cheC gene product of Escherichia coli plays a key role in regulating the direction of flagellar rotation during chemotactic responses. An attempt was made to identify other stimulus transduction elements that interact with the cheC component by examining cheC revertants for functional suppressors. Approximately two-thirds of the revertants studied appeared to be due to back mutation or to second-site mutations near or within the cheC structural gene. The remainder of the revertants carried suppressor mutations that mapped at the cheZ locus. Half of these suppressors impaired chemotaxis in a cheC+ background and were shown by complementation analysis to be defective in cheZ function. These suppressors corrected cheC defects in an allele-specific pattern, suggesting that the cheC and cheZ proteins are in direct contact and are mutually corrective due to protein-protein interaction. Observation of swimming patterns and flagellar rotation in cheC cheZ mutants demonstrated that the interaction of these two gene products influences both the spontaneous frequency of flagellar reversals and the ability of the rotational machinery to respond to chemotactic stimuli. A model of this interaction and its possible role in chemotaxis are discussed.
先前的研究表明，大肠杆菌的cheC基因产物在趋化反应过程中调节鞭毛旋转方向时起关键作用。通过检查cheC回复突变体的功能抑制子，试图鉴定与cheC组分相互作用的其他刺激转导元件。所研究的回复突变体中约三分之二似乎是由于回复突变或cheC结构基因附近或内部的第二位点突变。其余的回复突变体携带定位在cheZ位点的抑制子突变。这些抑制子中有一半在cheC+背景下损害趋化性，并且通过互补分析表明其cheZ功能有缺陷。这些抑制子以等位基因特异性模式纠正cheC缺陷，表明cheC和cheZ蛋白直接接触，并且由于蛋白质-蛋白质相互作用而相互纠正。对cheC cheZ突变体的游动模式和鞭毛旋转的观察表明，这两种基因产物的相互作用影响鞭毛反转的自发频率以及旋转机制对趋化刺激作出反应的能力。讨论了这种相互作用的模型及其在趋化性中的可能作用。
