title: Two-component regulatory system ActS/ActR is required for Sinorhizobium meliloti adaptation to oxidative stress.
abstract: The two-component system ActS/ActR plays important roles in bacterial adaptation to abiotic stress, including acid tolerance and oxidant resistance. However, the underlying regulatory mechanism is not clear. In this study, we found that the ActS/ActR system is required for adaptation to oxidative stress by regulating the transcription of the genes actR, katB, gshA and gshB1. The actS and actR mutants were sensitive to low pH and oxidants such as H2O2, oxidized glutathione (GSSG) and sodium nitroprusside (SNP). The expression of actR by using a plasmid rescued the defect of SNP sensitivity for all actS and actR mutants. The expression of actS and actR were suppressed by treatment with H2O2. The expression of actS, actR, oxyR, katA and katB was required for ActS and ActR under normal conditions. The induction of katB, gshA and gshB1 depended on ActS and ActR during treatment with H2O2and SNP. Our findings revealed that the ActS/ActR system is a key redox regulator in S. meliltoi and provides a new cue to understanding Rhizobium-legume symbiosis.
authors.affiliation: Shanghai Key Laboratory of Bio-energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, China; School of Communication & Information Engineering, Shanghai University, Shanghai 200444, China.
authors.forename: Guirong
authors.initials: G
authors.lastname: Tang
authors.affiliation: Shanghai Key Laboratory of Bio-energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, China.
authors.forename: Sunjun
authors.initials: S
authors.lastname: Wang
authors.affiliation: School of Life Sciences, Anhui University, Hefei 230039, China.
authors.forename: Dawei
authors.initials: D
authors.lastname: Lu
authors.affiliation: Shanghai Key Laboratory of Bio-energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, China.
authors.forename: Leqi
authors.initials: L
authors.lastname: Huang
authors.affiliation: Shanghai Key Laboratory of Bio-energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, China.
authors.forename: Ningning
authors.initials: N
authors.lastname: Li
authors.affiliation: Shanghai Key Laboratory of Bio-energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, China. Electronic address: liluo@shu.edu.cn.
authors.forename: Li
authors.initials: L
authors.lastname: Luo
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D015870:Gene Expression; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D006863:Hydrogen-Ion Concentration; D016877:Oxidants / Q000633:toxicity; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010957:Plasmids; D015398:Signal Transduction; D016962:Sinorhizobium meliloti / Q000187:drug effects / Q000235:genetics* / Q000502:physiology*; D013312:Stress, Physiological; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D016877:Oxidants
keywords: Gene expression; Oxidative stress; Sinorhizobium meliloti; Two-component system; actR/actS