Analysis of bvgR expression in Bordetella pertussis.
Bordetella pertussis, the causative agent of whooping cough, produces a wide array of factors that are associated with its ability to cause disease. The expression and regulation of these virulence factors are dependent upon the bvg locus, which encodes three proteins: BvgA, a 23-kDa cytoplasmic protein; BvgS, a 135-kDa transmembrane protein; and BvgR, a 32-kDa protein. It is hypothesized that BvgS responds to environmental signals and interacts with BvgA, a transcriptional regulator, which upon modification by BvgS binds to specific promoters and activates transcription. An additional class of genes is repressed by the products of the bvg locus. The repression of these genes is dependent upon the third gene, bvgR. Expression of bvgR is dependent upon the function of BvgA and BvgS. This led to the hypothesis that the binding of phosphorylated BvgA to the bvgR promoter activates the expression of bvgR. We undertook an analysis of the transcriptional activation of bvgR expression. We identified the bvgR transcript by Northern blot analysis and identified the start site of transcription by primer extension. We determined that transcriptional activation of the bvgR promoter in an in vitro transcription system requires the addition of phosphorylated BvgA. Additionally, we have identified cis-acting regions that are required for BvgA activation of the bvgR promoter by in vitro footprinting and in vivo deletion and linker scanning analyses. A model of BvgA binding to the bvgR promoter is presented.
Merkel
Tod J
TJ
Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland 20892, USA. merkel@cber.fda.gov
Boucher
Philip E
PE
Stibitz
Scott
S
Grippe
Vanessa K
VK
D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D001886:Bordetella pertussis / Q000235:genetics* / Q000472:pathogenicity; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D015398:Signal Transduction / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D015533:Transcriptional Activation; D014774:Virulence
D001426:Bacterial Proteins; C065601:BvgA protein, Bacteria; D014157:Transcription Factors; C080662:bvgS protein, Bordetella pertussis