Regulation of phosphatase activity in bacterial chemotaxis
Regulation of phosphatase activity in bacterial chemotaxis
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DOI：
10.1006/jmbi.1998.2224
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发表时间：
1998-12-11
影响因子：
5.6
通讯作者：
Eisenbach, M
中科院分区：
文献类型：
--
作者：
Blat, Y;Gillespie, B;Eisenbach, M
细菌趋化性是广泛分布的双组分调控系统家族中研究最多的信号模型系统。它由组氨酸激酶(CHEA)和特异性磷酸酶(CHEZ)介导的趋化反应调节因子CHEY的磷酸化水平的变化控制。虽然已知CHEA的活性是通过受体受到趋化刺激的调节，但尚未发现可能通过CHEZ调节CHEY去磷酸化的输入。我们用停流荧光法测定了CHEZ介导的CHEY去磷酸化动力学。将磷酸化的Chey(类似于P的Chey)与CHEZ混合后，去磷酸化的起始时间延迟了约50ms，并且在接近类似于P的新的稳定状态的过程中观察到了明显的超调。在一个高度活跃的突变体CHEZ蛋白(CheZ54RC)中没有观察到延迟和超调，该突变体不支持体内的趋化作用，并且似乎具有结构性活性。CHEZ对Chey的活性与P类似，Hill系数为2.5。观察到的CHEZ活性的延迟调节及其协同作用表明，磷酸酶活性是在CHEY水平上调节的，类似于P-CHEZ相互作用。这种反应调节因子与其磷酸酶之间的这种新的相互作用可能涉及信号调节和对趋化信号的适应。(C)1998年学术出版社。
Bacterial chemotaxis is the most studied model system for signaling by the widely spread family of two-component regulatory systems. It is controlled by changes in the phosphorylation level of the chemotactic response regulator, CheY, mediated by a histidine kinase (CheA) and a specific phosphatase (CheZ). While it is known that CheA activity is regulated, via the receptors, by chemotactic stimuli, the input that may regulate CheY dephosphorylation by CheZ has not been found. We measured, by using stopped-flow fluorometry, the kinetics of CheZ-mediated dephosphorylation of CheY. The onset of dephosphorylation was delayed by similar to 50 ms after mixing phosphorylated CheY (CheY similar to P) with CheZ, and a distinct overshoot was observed in the approach to the new steady state of CheY similar to P. The delay and overshoot were not observed in a hyperactive mutant CheZ protein (CheZ54RC) that does not support chemotaxis in vivo and appears to be constitutively active. CheZ activity was cooperative with respect to CheY similar to P, with a Hill-coefficient of 2.5. The observed delayed modulation of CheZ activity and its cooperativity suggest that the phosphatase activity is regulated at the level of CheY similar to P-CheZ interaction. This novel kind of interplay between a response regulator and its phosphatase may be involved in signal tuning and in adaptation to chemotactic signals. (C) 1998 Academic Press.