title: RpoS and RpoN are involved in the growth-dependent regulation of rfaH transcription and O antigen expression in Salmonella enterica serovar Typhi.
abstract: We reported earlier that the production of O antigen lipopolysaccharide (LPS) by Salmonella enterica serovar Typhi (Salmonella typhi) increases at the onset of stationary phase and correlates with a growth-regulated expression of the rfaH gene under the control of the alternative sigma factor RpoN (Microbiology 148 (2002) 3789). In this study, we demonstrate that RpoS also modulates rfaH promoter activity as revealed by the absence of growth-dependent regulation of an rfaH-lacZ transcriptional fusion and O antigen production in a S. typhi rpoS mutant. Introduction of a constitutively expressed rpoN gene into the rpoS mutant restored increased production of O antigen during stationary phase, suggesting that constitutive production of RpoN could overcome the RpoS defect. Similar results were observed when an rpoS rpoN double mutant was transformed with the intact rpoN gene. Thus, we conclude that both RpoS and RpoN control the rfaH promoter activity and concomitantly, the production of O-specific LPS in S. typhi.
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, P.O. Box 174 Correo 22, Santiago, Chile.
authors.forename: Mauricio
authors.initials: M
authors.lastname: Bittner
authors.forename: Soledad
authors.initials: S
authors.lastname: Saldías
authors.forename: Francisco
authors.initials: F
authors.lastname: Altamirano
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Valvano
authors.forename: Inés
authors.initials: I
authors.lastname: Contreras
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics; D004268:DNA-Binding Proteins; D012321:DNA-Directed RNA Polymerases / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D018507:Gene Expression Regulation, Developmental; D005798:Genes, Bacterial; D007763:Lac Operon; D009154:Mutation; D019081:O Antigens / Q000096:biosynthesis*; D010445:Peptide Elongation Factors / Q000096:biosynthesis / Q000235:genetics*; D011401:Promoter Regions, Genetic; D051877:RNA Polymerase Sigma 54; D012485:Salmonella typhi / Q000235:genetics* / Q000254:growth & development / Q000502:physiology*; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*; D015534:Trans-Activators / Q000096:biosynthesis / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D019081:O Antigens; D010445:Peptide Elongation Factors; C106401:RfaH protein, E coli; D012808:Sigma Factor; D015534:Trans-Activators; C497751:rpoN protein, E coli; C069567:sigma factor KatF protein, Bacteria; D012321:DNA-Directed RNA Polymerases; D051877:RNA Polymerase Sigma 54