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of Saccharmyces cerevisiae. Yeast 2006, 23:751–761.CrossRefPubMed Authors’ contributions HFC planned and designed the study, performed the experiments and analyzed the results and drafted the manuscript. YFY contributed equally. MSBK initiated and supervised the study, assisted in Wnt inhibitor data analysis and revised the manuscript. All authors read and approved the final manuscript.”
“Background Aerobic bacteria use oxygen as a terminal electron acceptor in oxygen-containing environments for their metabolism. Although aerobic growth Fossariinae has its obvious advantages (e. g. high energy efficiency, abundance of oxygen in the atmosphere, etc), bacteria must deal with the undesired consequences from exposure to oxygen and oxidative environments. Oxygen and

its derivatives, such as superoxide and hydrogen peroxide, are often highly reactive and pose a threat to many macromolecules, such as enzymes with iron-sulfur centers, nucleic acids, and lipids. Therefore, bacteria undergoing aerobic growth must be able to sense, respond to, and detoxify reactive oxygen species (ROS), and maintain their structural and functional integrities. The principle mechanism through which bacteria respond to environmental signals is through two-component and other regulatory systems [1, 2]. At least four global regulatory systems -OxyRS, SoxRS, Fnr and ArcAB – are identified to respond to oxygen and its derivatives [3, 4]. OxyRS and SoxRS systems control the response of bacteria to hydrogen peroxide and superoxide, respectively [3–12]. Fnr (fumarate and nitrate reduction) controls the transition from aerobic growth to anaerobic growth [13–17]. Fnr is believed to directly sense oxygen [18–20] and regulate at least 100 operons [21–23].