title: IscR plays a role in oxidative stress resistance and pathogenicity of a plant pathogen, Xanthomonas campestris.
abstract: Iron-sulfur ([Fe-S]) cluster is an essential cofactor of proteins involved in various physiological processes including cellular defense against oxidative stress. In Xanthomonas campestris pv. campestris (Xcc), IscR plays a negative role in regulation of the transcription of [Fe-S] assembly genes, iscR-sufBCDS. The expression level of sufBCDS was up-regulated in an Xcc iscR mutant. In addition, the iscR promoter activity in an Xcc iscR mutant was also higher than the wild-type strain, indicating an autoregulatory circuit. Purified IscR was shown to bind at the iscR promoter region and three putative IscR binding sites were identified. The expression of iscR-suf operon was highly induced by oxidant treatments and iron limited conditions. The iscR mutant showed increased sensitivity toward hydrogen peroxide phenotype but, surprisingly, had hyper-resistant phenotype toward plumbagin compared to the wild-type strain. Most importantly, the iscR mutant was impaired in its ability to cause lesion on leaves of a compatible host plant, Chinese radish (Raphanus sativus). These results demonstrate that a transcription regulator gene, iscR, negatively regulates genes involved in [Fe-S] biosynthesis and plays a role in oxidative stress response and pathogenesis of Xcc.
authors.affiliation: Laboratory of Biotechnology, Chulabhorn Research Institute, 54 Kamphaeng Phet 6 Road, Lak Si, Bangkok 10210, Thailand; Applied Biological Science Program, Chulabhorn Graduate Institute, 54 Kamphaeng Phet 6 Road, Lak Si, Bangkok 10210, Thailand.
authors.forename: Mayuree
authors.initials: M
authors.lastname: Fuangthong
authors.affiliation: Department of Biotechnology, Faculty of Science, Mahidol University, 272 Rama VI Road, Ratchathewi District, Bangkok 10400, Thailand.
authors.forename: Thichakorn
authors.initials: T
authors.lastname: Jittawuttipoka
authors.affiliation: Department of Biotechnology, Faculty of Science, Mahidol University, 272 Rama VI Road, Ratchathewi District, Bangkok 10400, Thailand.
authors.forename: Ratiphorn
authors.initials: R
authors.lastname: Wisitkamol
authors.affiliation: Laboratory of Biotechnology, Chulabhorn Research Institute, 54 Kamphaeng Phet 6 Road, Lak Si, Bangkok 10210, Thailand.
authors.forename: Adisak
authors.initials: A
authors.lastname: Romsang
authors.affiliation: Laboratory of Biotechnology, Chulabhorn Research Institute, 54 Kamphaeng Phet 6 Road, Lak Si, Bangkok 10210, Thailand.
authors.forename: Jintana
authors.initials: J
authors.lastname: Duang-nkern
authors.affiliation: Laboratory of Biotechnology, Chulabhorn Research Institute, 54 Kamphaeng Phet 6 Road, Lak Si, Bangkok 10210, Thailand; Applied Biological Science Program, Chulabhorn Graduate Institute, 54 Kamphaeng Phet 6 Road, Lak Si, Bangkok 10210, Thailand.
authors.forename: Paiboon
authors.initials: P
authors.lastname: Vattanaviboon
authors.affiliation: Laboratory of Biotechnology, Chulabhorn Research Institute, 54 Kamphaeng Phet 6 Road, Lak Si, Bangkok 10210, Thailand; Applied Biological Science Program, Chulabhorn Graduate Institute, 54 Kamphaeng Phet 6 Road, Lak Si, Bangkok 10210, Thailand; Department of Biotechnology, Faculty of Science, Mahidol University, 272 Rama VI Road, Ratchathewi District, Bangkok 10400, Thailand; Center for Environmental Health, Toxicology and Management of Chemicals, Bangkok, Thailand. Electronic address: skorn@cri.or.th.
authors.forename: Skorn
authors.initials: S
authors.lastname: Mongkolsuk
mesh_terms: D000595:Amino Acid Sequence; D015964:Gene Expression Regulation, Bacterial; D023061:Gene Order; D008969:Molecular Sequence Data; D009154:Mutation; D009876:Operon; D018384:Oxidative Stress / Q000235:genetics*; D010641:Phenotype; D010935:Plant Diseases / Q000382:microbiology; D011401:Promoter Regions, Genetic; D016415:Sequence Alignment; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014774:Virulence / Q000235:genetics; D016959:Xanthomonas campestris / Q000235:genetics* / Q000378:metabolism* / Q000472:pathogenicity
chemical_list: D014157:Transcription Factors
keywords: Iron–sulfur; IscR; Oxidative stress; Plant pathogen; Xanthomonas