title: Phenotypic analysis of Salmonella enterica serovar Typhimurium rpoE mutants encoding RNA polymerase extracytoplasmic stress response sigma factors σ(E) with altered promoter specificity.
abstract: We previously identified mutants in the rpoE gene of Salmonella enterica serovar Typhimurium (S. Typhimurium) encoding RNA polymerase extracytoplasmic stress response sigma factors σ(E) with altered promoter specificity. The replacement of the conserved R171 residue in the conserved region 4.2 of σ(E) by different amino acid residues exhibited different phenotypes. While R171A almost completely abolished sigma factor activity, R171G and R171C mutant changes imparted a relaxed recognition phenotype to the sigma factor. In the present study, we introduced these mutations into the S. Typhimurium chromosome to investigate their phenotype during ethanol stress and in promoter recognition. Both relaxed sigma factors were found to initiate transcription from a high number of artificial promoters in the S. Typhimurium genome. Both mutants had substantially decreased activity under stress conditions. However, this decreased activity and also the recognition of atypical promoters had no significant effect upon growth, even in stressful conditions.
authors.affiliation: Institute of Molecular Biology, Slovak Academy of Sciences, 845 51 Bratislava, Slovak Republic.
authors.forename: Bronislava
authors.initials: B
authors.lastname: Rezuchova
authors.forename: Dagmar
authors.initials: D
authors.lastname: Homerova
authors.forename: Beatrica
authors.initials: B
authors.lastname: Sevcikova
authors.forename: Renata
authors.initials: R
authors.lastname: Novakova
authors.forename: Lubomira
authors.initials: L
authors.lastname: Feckova
authors.forename: Mark
authors.initials: M
authors.lastname: Roberts
authors.forename: Jan
authors.initials: J
authors.lastname: Kormanec
mesh_terms: D000891:Anti-Infective Agents, Local / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D012321:DNA-Directed RNA Polymerases / Q000235:genetics / Q000378:metabolism; D000431:Ethanol / Q000494:pharmacology; D009154:Mutation; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012486:Salmonella typhimurium / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D012808:Sigma Factor / Q000235:genetics* / Q000378:metabolism; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics; D014158:Transcription, Genetic / Q000235:genetics
chemical_list: D000891:Anti-Infective Agents, Local; D001426:Bacterial Proteins; D012808:Sigma Factor; C063202:sporulation-specific sigma factors; D000431:Ethanol; D012321:DNA-Directed RNA Polymerases