Analysis of two regulators of Bordetella pertussis virulence Baf and Btr
AuthorWood, Gwendolyn Elna, 1969-
AdvisorFriedman, Richard L.
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
AbstractBordetella pertussis is the causative agent of the childhood disease whooping cough or pertussis. The regulation of virulence factor expression by two proteins (Baf and Btr) in this organism was studied. Pertussis toxin (ptx) transcription is activated by the two component BvgAS system. BvgAS-dependent ptx-lacZ expression in Escherichia coli can be achieved by DNA gyrase inhibitors, growth in minimal medium, or addition of the B. pertussis baf gene in trans. The mechanism by which Baf affects pertussis toxin expression in E. coli and B. pertussis is the subject of this investigation. In E. coli, wild type Baf increases ptx-lacZ expression, has no effect on bvgA-lacZ expression, yet increases BvgA protein levels 2-fold. In B. pertussis, ptx-lacZ expression is increased 10-fold when baf is overexpressed. However, BvgA protein levels are unaffected in B. pertussis as are pertussis toxin, adenylate cyclase toxin, and filamentous hemagglutinin levels. The effects of Baf on pertussis toxin expression in E. coli and B. pertussis is not due to a slowing of growth since overexpression of Baf does not affect growth rate. Finally, baf is shown to be an essential gene for viability, suggesting that Baf regulates the expression of other genes in addition to pertussis toxin in B. pertussis. Available data suggests Baf enhances BvgA function through an unknown mechanism. Possible models for Baf's role in pertussis toxin expression are discussed. Btr is an oxygen responsive transcriptional regulator homologous to the FNR protein of E. coli. Btr was shown to be important in growth and survival of B. pertussis in a mouse model. Btr-regulated genes were identified using a titration assay and include B. pertussis sodB and btr, E. coli aspA and a newly identified B. pertussis gene, brg1. brg1 is unaffected by Btr aerobically but is activated 3-fold by Btr under anaerobic growth conditions. brg1 encodes a protein similar to the LysR family of transcriptional regulators. The nucleotide sequence adjacent to brg1 was determined and found to encode proteins with similarity to various metabolic enzymes.
Degree ProgramGraduate College
Microbiology and Immunology