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Journal of Bacteriology, January 2001, p. 536-544, Vol. 183, No. 2
Division of Bacterial, Parasitic, and
Allergenic Products, Center for Biologics Evaluation and Research,
Food and Drug Administration, Bethesda, Maryland 20892
Received 18 September 2000/Accepted 26 October 2000
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~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.
0021-9193/01/$04.00+0 DOI: 10.1128/JB.183.2.536-544.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Genetic and Biochemical Analyses of BvgA
Interaction with the Secondary Binding Region of the fha
Promoter of Bordetella pertussis
*
Corresponding author. Mailing address: DBPAP, CBER,
USFDA, Building 29, Room 526, HFM-440, 8800 Rockville Pike, Bethesda, MD 20892. Phone: (301) 496-1785. Fax: (301) 402-2776. E-mail: boucher{at}cber.fda.gov.
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