title: EpsR modulates production of extracellular polysaccharides in the bacterial wilt pathogen Ralstonia (Pseudomonas) solanacearum.
abstract: Ralstonia solanacearum is the causal agent of bacterial wilt of many agriculturally important crops. Exopolysaccharide synthesized by products of the epsI operon is the major virulence factor for R. solanacearum. Expression of epsI has been demonstrated to be under the control of several proteins, including several two-component regulators. Overexpression of EpsR was found previously to reduce the amount of synthesis specifically from the epsI promoter. Here we present data that a single chromosomal copy of epsR activates the epsI promoter, suggesting that EpsR is a concentration-dependent effector of epsI gene expression. Furthermore, the ability of EpsR to modulate epsI expression is dependent on the phosphorylation state of EpsR. Gel mobility shift assays suggest that EpsR can specifically bind the epsI promoter and that this binding requires a phosphorylated form of EpsR.
authors.affiliation: Department of Biology, Indiana University, Bloomington 47405, USA.
authors.forename: M R
authors.initials: MR
authors.lastname: Chapman
authors.forename: C C
authors.initials: CC
authors.lastname: Kao
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000378:metabolism; D018628:Gene Dosage; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D016946:Gram-Negative Aerobic Rods and Cocci / Q000378:metabolism* / Q000472:pathogenicity; D009154:Mutation; D010766:Phosphorylation; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis* / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D012097:Repressor Proteins; D014157:Transcription Factors; D014675:Vegetables / Q000382:microbiology; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; C083492:EPSI polysaccharide; D011135:Polysaccharides, Bacterial; D012097:Repressor Proteins; D014157:Transcription Factors; C087016:epsR protein, Ralstonia solanacearum