Genetic and biochemical analyses of BvgA interaction with the secondary binding region of the fha promoter of Bordetella pertussis.
The BvgA-BvgS two-component signal transduction system regulates expression of virulence factors in Bordetella pertussis. The BvgA response regulator activates transcription by binding to target promoters, which include those for the genes encoding filamentous hemagglutinin (fha) and pertussis toxin (ptx). We have previously shown that at both promoters the phosphorylated form of BvgA binds multiple high- and low-affinity sites. Specifically, at the fha promoter, we proposed that there may be high- and a low-affinity binding sites for the BvgA dimer. In our present investigation, we used DNA binding analyses and in vitro and in vivo assays of promoters with substitutions and deletions to support and extend this hypothesis. Our observations indicate that (i) binding of BvgA approximately P to a primary (high-affinity) site and a secondary binding region (lower affinity) is cooperative, (ii) although both the primary binding site and the secondary binding region are required for full activity of the wild-type (undeleted) promoter, deletion of two helical turns within the secondary binding region can produce a fully active or hyperactive promoter, and (iii) BvgA binding to the secondary binding region shows limited DNA sequence specificity.
Boucher
P E
PE
Division of Bacterial, Parasitic, and Allergenic Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland 20892, USA. boucher@cber.fda.gov
Yang
M S
MS
Schmidt
D M
DM
Stibitz
S
S
D018829:Adhesins, Bacterial / Q000235:genetics*; D001426:Bacterial Proteins / Q000378:metabolism*; D001483:Base Sequence; D001886:Bordetella pertussis / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006388:Hemagglutinins / Q000235:genetics*; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D014157:Transcription Factors / Q000378:metabolism*; D010566:Virulence Factors, Bordetella
D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; C065601:BvgA protein, Bacteria; D004268:DNA-Binding Proteins; D006388:Hemagglutinins; D014157:Transcription Factors; D010566:Virulence Factors, Bordetella; C065273:filamentous hemagglutinin adhesin, Bordetella pertussis