Identification of a locus required for the regulation of bvg-repressed genes in Bordetella pertussis.
In Bordetella pertussis, the coordinate regulation of virulence factor expression is controlled by the products of the bvgAS locus. In the presence of modulating signals such as MgSO4, nicotinic acid, or reduced temperature, the expression of bvg-activated genes is reduced while the expression of bvg-repressed genes is induced. One model for the regulation of bvg-repressed genes predicts the existence of a repressor protein encoded by a bvg-activated gene. Once activated, the product of this bvg-activated gene would bind to and repress transcription from the bvg-repressed genes. We isolated five genetically independent transposon insertion mutants of B. pertussis that have a phenotype consistent with the knockout of a putative bvg-regulated repressor. These mutants constitutively expressed a vrg6-phoA transcriptional fusion but demonstrated normal bvgAS function. Genomic mapping and DNA sequence analysis of the sites of transposon insertion demonstrated that these mutants define a locus downstream of bvgAS. Introduction of an in-frame, 12-bp insertion within this locus also conferred the mutant phenotype, confirming that the phenotype seen in the transposon mutants is the result of disruption of a distinct gene, which we have designated bvgR, and is not a consequence of polar effects on bvgAS.
Merkel
T J
TJ
National Institute of Dental Research, NIH, Bethesda, MD 20892, USA.
Stibitz
S
S
D000469:Alkaline Phosphatase / Q000096:biosynthesis / Q000235:genetics; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics*; D001483:Base Sequence; D001886:Bordetella pertussis / Q000235:genetics* / Q000472:pathogenicity; D002874:Chromosome Mapping; D004251:DNA Transposable Elements; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000235:genetics*; D005816:Genetic Complementation Test; D008957:Models, Genetic; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009876:Operon / Q000235:genetics; D016364:Reading Frames / Q000235:genetics; D018085:Regulon / Q000235:genetics*; D012097:Repressor Proteins / Q000235:genetics*; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics; D014774:Virulence / Q000235:genetics
D001426:Bacterial Proteins; C065601:BvgA protein, Bacteria; D004251:DNA Transposable Elements; D012097:Repressor Proteins; D014157:Transcription Factors; C080662:bvgS protein, Bordetella pertussis; C079121:vrg protein, Bordetella pertussis; D000469:Alkaline Phosphatase