Nobre Lígia S, Al-Shahrour Fátima, Dopazo Joaquin, Saraiva Lígia M
Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Avenida da República (EAN), 2780-157 Oeiras, Portugal.
Department of Bioinformatics, Centro de Investigación Príncipe Felipe (CIPF), Valencia, E-46013, Spain.
Microbiology (Reading). 2009 Mar;155(Pt 3):813-824. doi: 10.1099/mic.0.023911-0.
We recently reported that carbon monoxide (CO) has bactericidal activity. To understand its mode of action we analysed the gene expression changes occurring when Escherichia coli, grown aerobically and anaerobically, is treated with the CO-releasing molecule CORM-2 (tricarbonyldichlororuthenium(II) dimer). Microarray analysis shows that the E. coli CORM-2 response is multifaceted, with a high number of differentially regulated genes spread through several functional categories, namely genes involved in inorganic ion transport and metabolism, regulators, and genes implicated in post-translational modification, such as chaperones. CORM-2 has a higher impact in E. coli cells grown anaerobically, as judged by the repression of genes belonging to eight functional classes which are not seen in the response of aerobically CORM-2-treated cells. The biological relevance of the variations caused by CORM-2 was substantiated by studying the CORM-2 sensitivity of selected E. coli mutants. The results show that the deletion of redox-sensing regulators SoxS and OxyR increased the sensitivity to CORM-2 and suggest that while SoxS plays an important role in protection against CORM-2 under both growth conditions, OxyR seems to participate only in the aerobic CORM-2 response. Under anaerobic conditions, we found that the heat-shock proteins IbpA and IbpB contribute to CORM-2 defence since the deletion of these genes increases the sensitivity of the strain. The induction of several met genes and the hypersensitivity to CORM-2 of the DeltametR, DeltametI and DeltametN mutant strains suggest that CO has effects on the methionine metabolism of E. coli. CORM-2 also affects the transcription of several E. coli biofilm-related genes and increases biofilm formation in E. coli. In particular, the absence of tqsA or bhsA increases the resistance of E. coli to CORM-2, and deletion of tsqA leads to a strain that has lost its capacity to form biofilm upon treatment with CORM-2. In spite of the relatively stable nature of the CO molecule, our results show that CO is able to trigger a significant alteration in the transcriptome of E. coli which necessarily has effects in several key metabolic pathways.
我们最近报道一氧化碳（CO）具有杀菌活性。为了解其作用方式，我们分析了在需氧和厌氧条件下生长的大肠杆菌用一氧化碳释放分子CORM - 2（二氯二羰基钌（II）二聚体）处理时发生的基因表达变化。微阵列分析表明，大肠杆菌对CORM - 2的反应是多方面的，大量差异调节基因分布在几个功能类别中，即参与无机离子转运和代谢的基因、调节因子以及涉及翻译后修饰的基因，如伴侣蛋白。从属于八个功能类别的基因受到抑制这一情况来看，CORM - 2对厌氧生长的大肠杆菌细胞影响更大，而在需氧条件下用CORM - 2处理的细胞反应中未观察到这种情况。通过研究选定的大肠杆菌突变体对CORM - 2的敏感性，证实了CORM - 2引起的变化的生物学相关性。结果表明，氧化还原感应调节因子SoxS和OxyR的缺失增加了对CORM - 2的敏感性，这表明虽然SoxS在两种生长条件下对抵御CORM - 2都起着重要作用，但OxyR似乎仅参与需氧条件下对CORM - 2的反应。在厌氧条件下，我们发现热休克蛋白IbpA和IbpB有助于抵御CORM - 2，因为这些基因的缺失会增加菌株的敏感性。几种met基因的诱导以及DeltametR、DeltametI和DeltametN突变体菌株对CORM - 2的超敏感性表明，CO对大肠杆菌的甲硫氨酸代谢有影响。CORM - 2还影响大肠杆菌几个与生物膜相关基因的转录，并增加大肠杆菌中的生物膜形成。特别是，tqsA或bhsA的缺失增加了大肠杆菌对CORM - 2的抗性，而tsqA的缺失导致菌株在用CORM - 2处理后失去形成生物膜的能力。尽管CO分子性质相对稳定，但我们的结果表明，CO能够引发大肠杆菌转录组的显著改变，这必然会对几个关键代谢途径产生影响。
