title: The global regulator GacS of a biocontrol bacterium Pseudomonas chlororaphis O6 regulates transcription from the rpoS gene encoding a stationary-phase sigma factor and affects survival in oxidative stress.
abstract: The global regulator, GacS (global activator for antibiotics and cyanide sensor kinase), of the rhizosphere bacterium Pseudomonas chlororaphis O6 (Pc O6) was required for increased resistance to hydrogen peroxide as cultures mature. Specific bands of peroxidase and catalase activity were absent in the stationary-phase cells of the Pc O6 gacS mutant, whereas a manganese superoxide dismutase (MnSOD) isozyme was expressed earlier and to a greater extent than in the wild-type. In the wild-type cell, transcript accumulation of rpoS was higher in late logarithmic (log)-phase cells than cells from mid log-phase or stationary-phase. Transcript abundance from rpoS was reduced in the gacS mutant throughout the growth phase compared to the wild-type expression. The sequence of a small RNA, rsmZ, found downstream of rpoS in other pseudomonads was lacking in Pc O6. This RNA is implicated in the control of genes activated by the GacS system. Thus, the mechanism by which GacS mediates the activation of genes under its control requires further investigation in Pc O6.
authors.affiliation: Agricultural Plant Stress Research Center and Institute of Agriculture Science, and Technology, College of Agriculture and Life Sciences, Chonnam National University, Gwangju 500-757, South Korea.
authors.forename: Beom Ryong
authors.initials: BR
authors.lastname: Kang
authors.forename: Baik Ho
authors.initials: BH
authors.lastname: Cho
authors.forename: Anne J
authors.initials: AJ
authors.lastname: Anderson
authors.forename: Young Cheol
authors.initials: YC
authors.lastname: Kim
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D002374:Catalase / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008969:Molecular Sequence Data; D009154:Mutation; D018384:Oxidative Stress; D009195:Peroxidase / Q000378:metabolism; D011549:Pseudomonas / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D012808:Sigma Factor / Q000235:genetics*; D013482:Superoxide Dismutase / Q000378:metabolism; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D001426:Bacterial Proteins; D012808:Sigma Factor; D014157:Transcription Factors; C069567:sigma factor KatF protein, Bacteria; D006861:Hydrogen Peroxide; D002374:Catalase; D009195:Peroxidase; D013482:Superoxide Dismutase; C074165:lemA protein, bacterial