A NOVEL DEVICE OF BACTERIAL SIGNAL TRANSDUCERS
A NOVEL DEVICE OF BACTERIAL SIGNAL TRANSDUCERS
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DOI：
10.1002/j.1460-2075.1994.tb06850.x
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发表时间：
1994-11-01
期刊：
影响因子：
11.4
通讯作者：
MIZUNO, T
中科院分区：
文献类型：
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作者：
ISHIGE, K;NAGASAWA, S;MIZUNO, T
ompC和ompF在大肠杆菌中的表达受一对细菌信号转导蛋白EnvZ（感觉激酶）和OmpR（反应调节因子）介导。我们分离出了以前的多拷贝抑制子，它可以弥补envZ缺失突变引起的磷酸转移信号转导缺陷。在这些抑制子中，arcB和barA是特别感兴趣的，因为这些基因产物在它们的一级氨基酸序列中含有自磷酸化组氨酸位点（或发射器模块）和磷酸接受天冬氨酸位点（或接收器模块）的意义上是独特的。在这里，我们报告说，ArcB和BarA拥有在C-末端区域的磷酸化组氨酸位点，从来没有注意到，除了以前确定的真实的。这种新发现的组氨酸在ArcB和BarA中被证明在观察到的多拷贝抑制中起着至关重要的作用。此外，体内和体外研究表明，含有组氨酸的C-末端结构域可以作为替代磷酸供体（或递质）。因此，这种新型的感觉激酶被发现含有两个独立的磷酸供体位点，以及一个磷酸接受位点。这些研究结果表明，这种独特的功能的ArcB和BarA，在信号模块方面，使这些感觉激酶有可能作为双信号转导。
The osmoregulatory expression of ompC and ompF in Escherichia coli is mediated by a pair of bacterial signal transduction proteins, EnvZ (sensory kinase) and OmpR (response regulator). We isolated previously multicopy suppressors which can complement a defect in the phosphotransfer signal transduction caused by an envZ deletion mutation. Among such suppressors, arcB and barA are of particular interest because these gene products are unique in the sense that they contain both an autophosphorylated histidine site (or transmitter module) and a phospho-accepting aspartate site (or receiver module) in their primary amino acid sequences. Here we report that ArcB and BarA possess in the C-terminal region a phosphorylated histidine site which has never been noticed, in addition to the authentic one identified previously. This newly identified histidine in ArcB and BarA was demonstrated to play a crucial role in the observed multicopy suppression. Furthermore, it was demonstrated iii vivo and in vitro for ArcB that the C-terminal domain containing the histidine can function as an alternative phosphodonor (or transmitter). This novel type of sensory kinase was therefore revealed to contain two independent phosphodonor sites, together with a phospho-accepting site. These findings suggest that this unique feature of ArcB and BarA, in terms of the signaling modules, make it possible for these sensory kinases to function as dual-signaling transducers.