Regulatory links between iron metabolism and oxidative stress in Rhodobacter sphaeroides

随着地球上氧气的出现，出现了活性氧物种，铁的利用率急剧下降。铁通过在Fenton反应中产生羟基自由基来加强氧毒性。因此，在氧气存在下的生命需要对铁的新陈代谢进行严格的调节，并与氧化应激防御的调节相结合。铁-硫团簇也是蛋白质重要的氧化还原敏感元件。我们以前的工作揭示了球形红杆菌中氧化应激与铁代谢的许多联系。因此，我们希望利用这一已建立的光营养模式生物来进一步阐明α变形杆菌中铁代谢的调节及其与氧化应激防御的联系。我们将确定影响铁代谢基因表达的调节因子，以响应氧化应激和铁限制或过量。同时，我们将调查已知或预测的铁和氧化还原调节因子在这些反应中的作用。关于野生型mRNA水平和蛋白质合成速率的现有数据将得到突变株研究和体外研究的补充，以阐明单个蛋白质和调控RNA的调节机制。球藻的代谢多样性使其能够区分铁的直接影响和氧化胁迫引起的次要影响，并分析光合作用复合体的影响。因此，这些研究将为细菌中铁代谢和氧化应激防御的共同调节提供新的见解。

With the appearance of oxygen on earth reactive oxygen species appeared and iron availability was drastically decreased. Iron potentiates oxygen toxicity by the production of hydroxyl radicals in the Fenton reaction. Thus life in the presence of oxygen requires a strict regulation of iron metabolism and its coupling with regulation of the oxidative stress defense. Iron-sulfur clusters are also important redox-sensing elements of proteins. Our previous work revealed many links of oxidative stress to iron metabolism in Rhodobacter sphaeroides. Therefore we want to use this established phototrophic model organism to further elucidate the regulation of iron metabolism in an alpha proteobacterium and its link to the oxidative stress defense. We will identify regulatory factors that affect expression of genes for iron metabolism in response to oxidative stress and iron limitation or excess. In parallel we will investigate the role of known or predicted iron and redox regulators in these responses. The available data on mRNA levels and protein synthesis rates in the wild type will be complemented by studies in mutant strains and by in vitro studies in order to elucidate the mechanisms of regulation by the individual proteins and regulatory RNAs. The metabolic versatility of R. sphaeroides allows to discriminate between direct effects of iron and secondary effects caused by oxidative stress and to analyze the impact of photosynthetic complexes. These studies will thus provide new insights into the co-regulation of iron metabolism and oxidative stress defense in bacteria.