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Journal of Bacteriology, March 2005, p. 1648-1658, Vol. 187, No. 5
0021-9193/05/$08.00+0     doi:10.1128/JB.187.5.1648-1658.2005

Activation of the vrg6 Promoter of Bordetella pertussis by RisA

Tadhg Ó. Cróinín,1,{dagger} Vanessa K. Grippe,1 and Tod J. Merkel1*

Laboratory of Respiratory and Special Pathogens, Division of Bacterial, Parasitic and Allergenic Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland1

Received 4 June 2004/ Accepted 17 November 2004

The BvgAS two-component system positively regulates the expression of the virulence genes of Bordetella pertussis and negatively regulates a second set of genes whose function is unknown. The BvgAS-mediated regulation of the bvg-repressed genes is accomplished through the activation of expression of the negative regulator, BvgR. A second two-component regulatory system, RisAS, is required for expression of the bvg-repressed surface antigens VraA and VraB. We examined the roles of BvgR and RisA in the regulation of four bvg-repressed genes in B. pertussis. Our analyses demonstrated that all four genes are repressed by the product of the bvgR locus and are activated by the product of the risA locus. Deletion analysis of the vrg6 promoter identified the upstream and downstream boundaries of the promoter and, in contrast to previously published results, demonstrated that sequences downstream of the start of transcription are not required for the regulation of expression of vrg6. Gel mobility-shift experiments demonstrated sequence-specific binding of RisA to the vrg6 and vrg18 promoters, and led to the identification of two putative RisA binding sites. Finally, transcriptional analysis and Western blot analysis demonstrated that BvgR regulates neither the expression nor the stability of RisA.

* Corresponding author. Mailing address: Laboratory of Respiratory and Special Pathogens, DBPAP/CBER/FDA, Building 29, Rm. 418, 8800 Rockville Pike, Bethesda, MD 20892. Phone: (301) 496-5564. Fax: (301) 402-2776. E-mail: merkel{at}cber.fda.gov.

{dagger} Present address: Department of Microbiology, Moyne Institute of Preventative Medicine, Trinity College Dublin, Dublin 2, Ireland.

Journal of Bacteriology, March 2005, p. 1648-1658, Vol. 187, No. 5
0021-9193/05/$08.00+0     doi:10.1128/JB.187.5.1648-1658.2005






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