Acetyl phosphate-dependent activation of a mutant PhoP response regulator that functions independently of its cognate sensor kinase
Acetyl phosphate-dependent activation of a mutant PhoP response regulator that functions independently of its cognate sensor kinase
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DOI：
10.1006/jmbi.2000.3848
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发表时间：
2000-07-07
影响因子：
5.6
通讯作者：
Groisman, EA
中科院分区：
文献类型：
--
作者：
Chamnongpol, S;Groisman, EA
双组分系统是一个信号通信网络，通常由一个传感器激酶组成，该激酶接收来自环境的输入，并修改执行自适应行为的响应调节器的磷酸化状态。PhoP是控制肠沙门氏菌毒力基因表达的反应调节因子。phop调控基因的转录是通过传感器PhoQ检测到的Mg2+水平来调节的。在这里，我们描述了PhoP突变蛋白PhoP*，它在缺乏其同源传感器的情况下起作用，从而允许PhoP激活基因的转录独立于环境中的Mg2+浓度。PhoP*蛋白在应答调节受体结构域中含有一个S93N取代。PhoP*介导的转录被作为ypta编码的磷酸化乙酰化酶的磷酸化位点或失活位点在应答调节因子中保守的天冬氨酸残基突变所取消。该酶介导乙酰磷酸的产生，乙酰磷酸已被证明是某些反应调节因子的低分子质量磷酸供体。纯化后的PhoP*蛋白在体外由乙酰磷酸自磷酸化比野生型PhoP蛋白更有效。PhoP*蛋白保留了与PhoQ蛋白相互作用的能力，这在体外促进了PhoP*蛋白的磷酸化，并在体内高Mg2+浓度下消除了PhoP*介导的转录。总的来说，我们的研究结果揭示了PhoQ在毫摩尔Mg2+生长过程中的转录抑制作用，并定义了一种突变反应调节形式，其被乙酰磷酸磷酸化的能力增加。(C) 2000年学术出版社。
The two-component system is a signal communication network generally consisting of a sensor kinase that receives inputs from the environment and modifies the phosphorylated state of a response regulator that executes an adaptive behavior. PhoP is a response regulator that controls virulence gene expression in Salmonella enterica. Transcription of PhoP-regulated genes is modulated by the Mg2+ levels detected by the sensor PhoQ. Here, we describe a PhoP mutant protein, PhoP*, that functions in the absence of its cognate sensor, thereby allowing transcription of PhoP-activated genes independently of the Mg2+ concentration in the environment. The PhoP* protein harbors a S93N substitution in the response regulator receiver domain. PhoP*-mediated transcription is abolished by either mutation of the aspartate residue that is conserved among response regulators as the site of phosphorylation or inactivation of the ypta-encoded phosphotransacetylase. This enzyme mediates the production of acetyl phosphate, which has been shown to serve as a low molecular mass phosphate donor for certain response regulators. The purified PhoP* protein autophosphorylated from acetyl phosphate more efficiently than the wild-type PhoP protein in vitro. The PhoP* protein retained the capacity to interact with the PhoQ protein, which promoted phosphorylation of the PhoP* protein in vitro and abolished PhoP*mediated transcription under high Mg2+ concentrations in vivo. Cumulatively, our results uncover a role of PhoQ in transcriptional repression during growth in millimolar Mg2+ and define a mutant response regulator form with an increased capacity to be phosphorylated by acetyl phosphate. (C) 2000 Academic Press.