title: OxyR, an important oxidative stress regulator to phenazines production and hydrogen peroxide resistance in Pseudomonas chlororaphis GP72.
abstract: Pseudomonas chlororaphis GP72 is an important plant growth-promoting rhizobacteria (PGPR) with a wide-spectrum antibiotic activity toward several soil-borne pathogens. The adaption of this strain to different environmental oxidative stress and redox phenazine pigment by the predicted regulator OxyR were investigated. The deletion of oxyR led to a significant reduction of the viability, production of three phenazine derivatives and resistance to hydrogen peroxide and paraquat on the KB agar plates. However, the mutant ΔoxyR grew better with shorter delay. In addition, the mutant ΔoxyR showed an increased resistance to hydrogen peroxide, which occurred at the concentration varying from 1.0mM to 5.0mM in the KB broth, as compared with the wild type. In addition, the biofilm formation ability was obviously enhanced and influenced by the different oxidants in the mutant. Quantitative RT-PCR experiments indicated that the expression of katG, ahpC, ahpD and phzE were increased in the oxyR mutant background in response to hydrogen peroxide. katG was mainly responsible for the enhanced resistance to hydrogen peroxide. The loss of oxyR is suggested to benefit the hydrogen peroxide inducible gene expression. Thus, OxyR is an important global regulator that regulates multiple pathways to enhance the survival of P. chlororaphis GP72 exposed to different oxidative stresses.
authors.affiliation: State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, People's Republic of China.
authors.forename: Kan
authors.initials: K
authors.lastname: Xie
authors.forename: Huasong
authors.initials: H
authors.lastname: Peng
authors.forename: Hongbo
authors.initials: H
authors.lastname: Hu
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Xuehong
authors.initials: X
authors.lastname: Zhang
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D024881:Drug Resistance, Bacterial; D017353:Gene Deletion; D020869:Gene Expression Profiling; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000633:toxicity*; D050296:Microbial Viability / Q000187:drug effects; D008969:Molecular Sequence Data; D016877:Oxidants / Q000378:metabolism / Q000633:toxicity*; D018384:Oxidative Stress; D010269:Paraquat / Q000378:metabolism / Q000633:toxicity; D010619:Phenazines / Q000378:metabolism*; D011549:Pseudomonas / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D004269:DNA, Bacterial; D016877:Oxidants; D010619:Phenazines; D015534:Trans-Activators; D006861:Hydrogen Peroxide; D010269:Paraquat
keywords: Biofilm; Oxidative stress; OxyR; Phenazine; Pseudomonas chlororaphis