Search tips
Search criteria 


Logo of jbacterPermissionsJournals.ASM.orgJournalJB ArticleJournal InfoAuthorsReviewers
J Bacteriol. 1993 June; 175(11): 3468–3479.
PMCID: PMC204746

Flagellin gene transcription in Bordetella bronchiseptica is regulated by the BvgAS virulence control system.


The products of the bvgAS locus activate expression of a majority of the known Bordetella virulence factors but also exert negative control over a class of genes called vrg genes (bvg-repressed genes). BvgAS negatively controls the production of flagella and the phenotype of motility in Bordetella bronchiseptica. In this study flaA, the flagellin gene, was cloned and characterized to facilitate studies of this negative control pathway. An internal flaA probe detected hybridizing sequences on genomic Southern blots of Bordetella pertussis, Bordetella parapertussis, and Bordetella avium, although B. pertussis and B. parapertussis are nonmotile. FlaA is similar to the FliC flagellins of Salmonella typhimurium and Escherichia coli, and flaA complemented an E. coli flagellin mutant. Insertional inactivation of the chromosomal flaA locus eliminated motility, which was restored by complementation with the wild-type locus. Analysis of flaA mRNA production by Northern (RNA) blotting and primer extension indicated that negative regulation by BvgAS occurs at the level of transcription. The transcriptional start site of flaA mapped near a consensus site for the alternative sigma factor, sigma F, encoded by fliA in E. coli and S. typhimurium. Consistent with a role for a fliA analog in B. bronchiseptica, transcriptional activation of a flaA-lacZ fusion in E. coli required fliA and a flaA-linked locus designated also efficiently complemented mutations in the flagellar master regulatory locus, flhDC, of E. coli. Our analysis of the motility phenotype of B. bronchiseptica suggests that the Bordetella virulence control system mediates transcriptional control of flaA through a regulatory hierarchy that includes the frl locus and an alternative sigma factor.

Full text

Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (2.9M), or click on a page image below to browse page by page.

Images in this article

Click on the image to see a larger version.

Articles from Journal of Bacteriology are provided here courtesy of American Society for Microbiology (ASM)