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首页> 外文期刊>Journal of bacteriology >TouR-Mediated Effector-Independent Growth Phase-Dependent Activation of the σ54 Ptou Promoter of Pseudomonas stutzeri OX1
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TouR-Mediated Effector-Independent Growth Phase-Dependent Activation of the σ54 Ptou Promoter of Pseudomonas stutzeri OX1

机译:斯图氏假单胞菌OX1的σ54Ptou启动子的TouR介导的效应子无关的生长阶段依赖性激活

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Transcription of the catabolic touABCDEF operon, encoding the toluene-o-xylene monooxygenase of Pseudomonas stutzeri OX1, is driven by the σ54-dependent Ptou promoter, whose activity is controlled by the phenol-responsive NtrC-like activator TouR. In this paper we describe for the first time a peculiar characteristic of this system, namely, that Ptou transcription is activated in a growth phase-dependent manner in the absence of genuine effectors of the cognate TouR regulator. This phenomenon, which we named gratuitous activation, was observed in the native strain P. stutzeri OX1, as well as in a Pseudomonas putida PaW340 host harboring the reconstructed tou regulatory circuit. Regulator-promoter swapping experiments demonstrated that the presence of TouR is necessary and sufficient for imposing gratuitous activation on the Ptou promoter, as well as on other σ54-dependent catabolic promoters, whereas the highly similar phenol-responsive activator DmpR is unable to activate the Ptou promoter in the absence of effectors. We show that this phenomenon is specifically triggered by carbon source exhaustion but not by nitrogen starvation. An updated model of the tou regulatory circuit is presented.
机译:分解代谢 touABCDEF 操纵子的转录是由σ 54驱动的,该操纵子编码 stutzeri OX1的甲苯- o -二甲苯单加氧酶。 依赖的P tou 启动子,其活性受酚响应性NtrC样激活剂TouR的控制。在本文中,我们首次描述了该系统的特殊特征,即在缺乏真正的TouR调节子的真正效应子的情况下,P tou 转录以生长相依赖的方式被激活。在天然菌株 P中观察到了这种现象,我们将其称为无偿激活。 stutzeri OX1以及带有重构的 tou 调节回路的恶臭假单胞菌 PaW340宿主。调节剂-启动子交换实验表明,TouR的存在对于在P tou 启动子以及其他依赖于σ 54 的分解代谢启动子上进行无偿激活是必要和充分的,而在缺乏效应子的情况下,高度相似的酚响应性激活剂DmpR无法激活P tou 启动子。我们表明,这种现象是由碳源耗尽引起的,而不是由氮饥饿引起的。给出了 tou 调节电路的更新模型。

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