title: The RpoS Sigma Factor Negatively Regulates Production of IAA and Siderophore in a Biocontrol Rhizobacterium, Pseudomonas chlororaphis O6.
abstract: The stationary-phase sigma factor, RpoS, influences the expression of factors important in survival of Pseudomonas chlororaphis O6 in the rhizosphere. A partial proteomic profile of a rpoS mutant in P. chlororaphis O6 was conducted to identify proteins under RpoS regulation. Five of 14 differentially regulated proteins had unknown roles. Changes in levels of proteins in P. chlororaphis O6 rpoS mutant were associated with iron metabolism, and protection against oxidative stress. The P. chlororaphis O6 rpoS mutant showed increased production of a pyoverdine-like siderophore, indole acetic acid, and altered isozyme patterns for peroxidase, catalase and superoxide dismutase. Consequently, sensitivity to hydrogen peroxide exposure increased in the P. chlororaphis O6 rpoS mutant, compared with the wild type. Taken together, RpoS exerted regulatory control over factors important for the habitat of P. chlororaphis O6 in soil and on root surfaces. The properties of several of the proteins in the RpoS regulon are currently unknown.
authors.affiliation: Institute of Environmentally-Friendly Agriculture, Chonnam National University, Gwangju 500-757, Korea.
authors.forename: Sang A
authors.initials: SA
authors.lastname: Oh
authors.affiliation: Institute of Environmentally-Friendly Agriculture, Chonnam National University, Gwangju 500-757, Korea.
authors.forename: Ji Soo
authors.initials: JS
authors.lastname: Kim
authors.affiliation: Institute of Environmentally-Friendly Agriculture, Chonnam National University, Gwangju 500-757, Korea.
authors.forename: Ju Yeon
authors.initials: JY
authors.lastname: Park
authors.affiliation: Institute of Environmentally-Friendly Agriculture, Chonnam National University, Gwangju 500-757, Korea.
authors.forename: Song Hee
authors.initials: SH
authors.lastname: Han
authors.affiliation: Department of Biology, Utah State University, Logan, UT, USA.
authors.forename: Christian
authors.initials: C
authors.lastname: Dimkpa
authors.affiliation: Department of Biology, Utah State University, Logan, UT, USA.
authors.forename: Anne J
authors.initials: AJ
authors.lastname: Anderson
authors.affiliation: Institute of Environmentally-Friendly Agriculture, Chonnam National University, Gwangju 500-757, Korea.
authors.forename: Young Cheol
authors.initials: YC
authors.lastname: Kim
keywords: indole acetic acid; iron; oxidative stress; proteomic analysis; sigma factor RpoS