Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China.
PLoS One. 2010 Dec 28;5(12):e15295. doi: 10.1371/journal.pone.0015295.
In the genome of Shewanella oneidensis, genes encoding the global regulators ArcA, Crp, and EtrA have been identified. All these proteins deviate from their counterparts in E. coli significantly in terms of functionality and regulon. It is worth investigating the involvement and relationship of these global regulators in aerobic and anaerobic respiration in S. oneidensis. In this study, the impact of the transcriptional factors ArcA, Crp, and EtrA on aerobic and anaerobic respiration in S. oneidensis were assessed. While all these proteins appeared to be functional in vivo, the importance of individual proteins in these two major biological processes differed. The ArcA transcriptional factor was critical in aerobic respiration while the Crp protein was indispensible in anaerobic respiration. Using a newly developed reporter system, it was found that expression of arcA and etrA was not influenced by growth conditions but transcription of crp was induced by removal of oxygen. An analysis of the impact of each protein on transcription of the others revealed that Crp expression was independent of the other factors whereas ArcA repressed both etrA and its own transcription while EtrA also repressed arcA transcription. Transcriptional levels of arcA in the wild type, crp, and etrA strains under either aerobic or anaerobic conditions were further validated by quantitative immunoblotting with a polyclonal antibody against ArcA. This extensive survey demonstrated that all these three global regulators are functional in S. oneidensis. In addition, the reporter system constructed in this study will facilitate in vivo transcriptional analysis of targeted promoters.
在希瓦氏菌属的基因组中，已经鉴定出编码全局调节剂 ArcA、Crp 和 EtrA 的基因。所有这些蛋白质在功能和调控组方面与大肠杆菌中的对应物有很大的不同。值得研究这些全局调节剂在希瓦氏菌属的需氧和厌氧呼吸中的参与和关系。在这项研究中，评估了转录因子 ArcA、Crp 和 EtrA 对希瓦氏菌属需氧和厌氧呼吸的影响。虽然所有这些蛋白质在体内似乎都具有功能，但它们在这两个主要生物过程中的重要性不同。ArcA 转录因子在需氧呼吸中至关重要，而 Crp 蛋白在厌氧呼吸中是必不可少的。使用新开发的报告系统，发现 arcA 和 etrA 的表达不受生长条件的影响，但 crp 的转录是在去除氧气时诱导的。对每种蛋白质对其他蛋白质转录的影响的分析表明，Crp 的表达不依赖于其他因素，而 ArcA 抑制了 etrA 和其自身的转录，而 EtrA 也抑制了 arcA 的转录。用针对 ArcA 的多克隆抗体通过定量免疫印迹进一步验证了野生型、crp 和 etrA 菌株在有氧或厌氧条件下 arcA 的转录水平。这项广泛的调查表明，这三种全局调节剂在希瓦氏菌属中都具有功能。此外，本研究构建的报告系统将有助于靶向启动子的体内转录分析。
