Toews M L, Goy M F, Springer M S, Adler J
Proc Natl Acad Sci U S A. 1979 Nov;76(11):5544-8. doi: 10.1073/pnas.76.11.5544.
A group of methylated proteins, the methyl-accepting chemotaxis proteins (MCP), has been shown to play a central role in bacterial chemotaxis. Both methylation and demethylation of MCP occur continuously in the absence of added stimuli; these two processes are in balance such that a basal level of methylation is maintained. Attractants cause the methylation level to increase to a new value, whereas repellents bring about a decrease in level. Therefore, attractants and repellents must somehow perturb the balance between methylation and demethylation of MCP. In this report the effect of attractants on demethylation of MCP was monitored in two ways: (i) by following the disappearance of [methyl-3H]MCP and (ii) by measuring formation of [3H]methanol, the product of MCP demethylation. Both methods showed that addition of attractants causes a transient inhibition of MCP demethylation. Repellent addition has previously been shown to stimulate MCP demethylation. It is therefore concluded that control of demethylation plays a crucial role in changing the level of methylation of MCP in response to attractants and repellents.
一类甲基化蛋白,即甲基接受趋化蛋白(MCP),已被证明在细菌趋化作用中起核心作用。在没有添加刺激物的情况下,MCP的甲基化和去甲基化都持续发生;这两个过程处于平衡状态,从而维持甲基化的基础水平。引诱剂会使甲基化水平增加到一个新值,而驱避剂则会导致水平下降。因此,引诱剂和驱避剂必定以某种方式扰乱了MCP甲基化和去甲基化之间的平衡。在本报告中,通过两种方式监测引诱剂对MCP去甲基化的影响:(i)追踪[甲基-3H]MCP的消失情况,以及(ii)测量MCP去甲基化产物[3H]甲醇的形成。两种方法均表明,添加引诱剂会导致MCP去甲基化的短暂抑制。先前已表明添加驱避剂会刺激MCP去甲基化。因此得出结论,去甲基化的控制在响应引诱剂和驱避剂时改变MCP甲基化水平方面起着关键作用。