Involvement of multiple transcription factors for metal-induced spy gene expression in Escherichia coli.
Involvement of multiple transcription factors for metal-induced spy gene expression in Escherichia coli.
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DOI：
10.1016/j.jbiotec.2007.08.002
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发表时间：
2008-01
影响因子：
4.1
通讯作者：
Kaneyoshi Yamamoto;H. Ogasawara;A. Ishihama
中科院分区：
文献类型：
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作者：
Kaneyoshi Yamamoto;H. Ogasawara;A. Ishihama
细菌直接暴露于环境中的金属。为了维持细胞内的金属稳态，大肠杆菌含有许多基因调控系统，每个系统对特定的金属做出反应。E.结果表明，在短时间内，铜离子对大肠杆菌的细胞增殖具有CpxAR依赖性诱导作用。长时间暴露于锌离子也诱导了spy基因的转录。然而，这种诱导依赖于另一个双组分系统BaeSR。使用DNase-I足迹分析，我们确定了两个BaeR结合区的间谍启动子与直接重复的BaeR盒序列，TCTNCANAA。将锌响应的BaeR结合位点与铜响应的CpxR结合位点分离，这意味着spy启动子通过不同的传感器-响应调节系统独立地响应两种金属。由于BaeSR依赖的锌反应需要较长的时间，因此外部锌对spy基因转录的诱导可能包括多个步骤，例如通过BaeSR感知锌诱导的包膜紊乱。
Bacteria are directly exposed to metals in environment. To maintain the intracellular metal homeostasis, Escherichia coli contain a number of gene regulation systems, each for response to a specific metal. A periplasmic protein Spy of E. coli was found to be induced upon short-exposure to copper ion in CpxAR-dependent manner. Transcription of the spy gene was also induced by long-exposure to zinc ion. This induction, however, depended on another two-component system BaeSR. Using DNase-I footprinting assay, we identified two BaeR-binding regions on the spy promoter with a direct repeat of the BaeR-box sequence, TCTNCANAA. The zinc-responsive BaeR-binding sites were separated from copper-responsive CpxR-binding site, implying that the spy promoter responds to two species of metal independently through different using sensor-response regulator systems. Since BaeSR-dependent zinc response requires longer time, the induction of spy gene transcription by external zinc may include multiple steps such as through sensing the zinc-induced envelope disorder by BaeSR.