Oosawa K, Imae Y
J Bacteriol. 1984 Feb;157(2):576-81. doi: 10.1128/jb.157.2.576-581.1984.
The addition of glycerol or ethylene glycol caused not only severe tumbling but also a drastic decrease in the methylation level of methyl-accepting chemotaxis proteins (MCPs) in Escherichia coli. Experiments with various mutants having defects in their MCPs showed that the demethylation occurred in all three kinds of MCPs, MCPI, II, and III. The addition of an attractant to the glycerol- or ethylene glycol-treated cells resulted in a distinct increase in the methylation level of the relevant MCP, indicating that glycerol and ethylene glycol do not directly damage the methylation-demethylation system in the cell. The time courses of adaptation and MCP demethylation upon addition of these repellents were consistent with each other. Furthermore, both the response time and the extent of MCP demethylation were increased in parallel with increasing concentrations of glycerol or ethylene glycol. These results indicate that the adaptation to these repellents is performed by the demethylation of MCPs. Thus, glycerol and ethylene glycol are novel repellents, which utilize not just one but all three kinds of MCPs for both information processing and adaptation.
添加甘油或乙二醇不仅会导致大肠杆菌剧烈翻滚，还会使甲基化趋化蛋白（MCPs）的甲基化水平急剧下降。对MCPs存在缺陷的各种突变体进行的实验表明，三种类型的MCPs，即MCP I、II和III均发生了去甲基化。向经甘油或乙二醇处理的细胞中添加引诱剂会导致相关MCP的甲基化水平明显升高，这表明甘油和乙二醇不会直接损害细胞中的甲基化-去甲基化系统。添加这些驱避剂后适应过程和MCP去甲基化的时间进程相互一致。此外，随着甘油或乙二醇浓度的增加，MCP去甲基化的响应时间和程度均平行增加。这些结果表明，对这些驱避剂的适应是通过MCPs的去甲基化来实现的。因此，甘油和乙二醇是新型驱避剂，它们在信息处理和适应过程中不仅利用一种，而是利用所有三种类型的MCPs。
