title: Chloro-benzoquinones cause oxidative DNA damage through iron-mediated ROS production in Escherichia coli.
abstract: Chloro-benzoquinones (CBQs) are a group of disinfection byproducts that are suspected to be potentially carcinogenic. Here, the mechanism of DNA damage caused by CBQs in the presence of ferrous ions was investigated in an Escherichia coli wild type M5 strain and a mutant L5 (ahpCF katEG mutant) strain that carried an enhanced green fluorescent protein reporter under the control of a SOS response gene (recA) promoter. All tested CBQs (including para-benzoquinone, 2-chloro-para-benzoquinone, and dichloro-para-benzoquinones with different substitutes) caused substantial oxidative DNA damage with EC50 values in the micromolar range. Moreover, 2,5-dichloro-para-benzoquinone (2,5-DCBQ), a typical CBQ, caused substantial ROS production in E. coli mutant cells. And ROS scavengers provided partial protective effects on genotoxicity of 2,5-DCBQ to E. coli mutant cells. The addition of Fe(2+) to the 2,5-DCBQ exposure system caused an increase in DNA oxidative damage; iron-chelating agents could partially prevent these cells from DNA damage. Finally, intracellular AhpCF, catalase E, and catalase G were all found to play an important role in the survival of E. coli cells exposed to CBQs, as indicated by an increased sensitivity of the ahpCF katEG mutant L5 strain to treatment compared with wild type M5 cells. Taken together, these results suggest that CBQs cause oxidative DNA damage in E. coli cells through the participation of iron-mediated ROS production.
authors.affiliation: State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Donghu South Road 7, Wuhan 430072, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Shuangqing Road 18, Beijing 100085, China.
authors.forename: Zhilan
authors.initials: Z
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Donghu South Road 7, Wuhan 430072, China. Electronic address: qhzhou@ihb.ac.cn.
authors.forename: Qiaohong
authors.initials: Q
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Shuangqing Road 18, Beijing 100085, China; University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China.
authors.forename: Dandan
authors.initials: D
authors.lastname: Zou
authors.affiliation: State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Donghu South Road 7, Wuhan 430072, China; University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Tian
authors.affiliation: State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Donghu South Road 7, Wuhan 430072, China. Electronic address: liuby@ihb.ac.cn.
authors.forename: Biyun
authors.initials: B
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Donghu South Road 7, Wuhan 430072, China.
authors.forename: Yongyuan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Donghu South Road 7, Wuhan 430072, China.
authors.forename: Zhenbin
authors.initials: Z
authors.lastname: Wu
mesh_terms: D016227:Benzoquinones / Q000633:toxicity*; D002374:Catalase / Q000378:metabolism; D004249:DNA Damage; D004203:Disinfection; D004926:Escherichia coli / Q000187:drug effects* / Q000378:metabolism; D007501:Iron / Q000378:metabolism; D010084:Oxidation-Reduction; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D016227:Benzoquinones; D017382:Reactive Oxygen Species; C004532:quinone; D007501:Iron; D002374:Catalase; C025225:2-benzoquinone
keywords: Chloro-benzoquinones; E. coli ahpCF katEG mutants; Iron ion; Oxidative DNA damage; ROS