title: Transcription of the Salmonella typhimurium spv virulence locus is regulated negatively by the nucleoid-associated protein H-NS.
abstract: The possibility that the pleiotropic transcriptional regulator H-NS might play a role in regulating expression of the spv virulence locus of Salmonella typhimurium was investigated. A transposon insertion mutation in hns, the gene encoding H-NS, resulted in enhanced transcription of the spvR regulatory gene and the spvB structural gene in stationary phase cultures. Enhanced transcription was not detected prior to stationary phase, indicating that H-NS makes a negative contribution that is growth phase-specific to the control of spv transcription. When H-NS was over-expressed from a multicopy plasmid, the normal stationary phase induction of spv transcription seen in wild-type cells was abolished. spv transcription was also found to be modulated by growth medium osmolarity, a feature common to many H-NS-regulated genes. In addition, transcription of the spv genes was reduced in mutants with abnormal levels of DNA supercoiling.
authors.affiliation: Department of Biochemistry, University of Dundee, UK.
authors.forename: C P
authors.initials: CP
authors.lastname: O'Byrne
authors.forename: C J
authors.initials: CJ
authors.lastname: Dorman
mesh_terms: D000220:Adaptation, Biological / Q000235:genetics; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D001426:Bacterial Proteins; D002455:Cell Division; D004269:DNA, Bacterial / Q000378:metabolism; D004278:DNA, Superhelical / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D016254:Mutagenesis, Insertional; D009876:Operon; D009997:Osmotic Pressure; D012486:Salmonella typhimurium / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity; D014158:Transcription, Genetic; D014774:Virulence / Q000235:genetics
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004278:DNA, Superhelical; D004268:DNA-Binding Proteins; C031908:H-NS protein, bacteria