title: Cloning and characterization of btr, a Bordetella pertussis gene encoding an FNR-like transcriptional regulator.
abstract: To determine whether hemolytic factors other than the bifunctional hemolysin-adenylate cyclase toxin (cyclolysin) are expressed by Bordetella pertussis, a gene library was constructed from a virulent strain of B. pertussis, BP504, transformed into nonhemolytic Escherichia coli, and screened on blood agar plates. A strongly hemolytic colony which contained the plasmid pHLY1A was isolated. Nucleotide sequencing of pHLY1A revealed an open reading frame that could encode a 27-kDa protein. No similarity was detected between the deduced amino acid sequence of this open reading frame and those of any known bacterial cytolysins. However, significant homology was detected with FNR of E. coli and several other transcriptional regulators including HylX from Actinobacillus pleuropneumoniae, which can also confer a hemolytic phenotype on E. coli. An fnr mutant of E. coli, JRG1728, could be complemented by pHLY1A. Thus, the B. pertussis transcriptional regulator-like gene and the protein which it encoded were named btr and BTR, respectively. A BTR-deficient B. pertussis strain, BJB1, was constructed. The btr::kan mutation had no effect on the expression of hemolytic activity or on phase variation. Northern (RNA) blotting revealed that btr expression was not regulated by the BvgAS two-component sensor-regulator. On the basis of sequence similarity to FNR-like transcriptional regulators and the ability to complement an anaerobically deficient E. coli strain (JRG1728) in growing anaerobically, BTR may regulate B. pertussis gene expression in response to changes in oxygen levels or to changes in the redox potential of the bacterial environment. Its role in virulence remains to be determined.
authors.affiliation: Department of Microbiology and Immunology, University of Arizona, Tucson 85724.
authors.forename: J D
authors.initials: JD
authors.lastname: Bannan
authors.forename: M J
authors.initials: MJ
authors.lastname: Moran
authors.forename: J I
authors.initials: JI
authors.lastname: MacInnes
authors.forename: G A
authors.initials: GA
authors.lastname: Soltes
authors.forename: R L
authors.initials: RL
authors.lastname: Friedman
mesh_terms: D016977:Actinobacillus pleuropneumoniae / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D015139:Blotting, Southern; D001886:Bordetella pertussis / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity; D003001:Cloning, Molecular; D017124:Conserved Sequence; D017931:DNA Primers; D004269:DNA, Bacterial / Q000302:isolation & purification; D004268:DNA-Binding Proteins; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D015698:Genomic Library; D006461:Hemolysis; D007506:Iron-Sulfur Proteins; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010957:Plasmids; D012329:RNA, Bacterial / Q000302:isolation & purification; D015183:Restriction Mapping; D017386:Sequence Homology, Amino Acid; D012756:Sheep; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics*
chemical_list: C084167:BTR protein, Bordetella pertussis; D001426:Bacterial Proteins; D017931:DNA Primers; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C060704:FNR protein, E coli; D007506:Iron-Sulfur Proteins; D012329:RNA, Bacterial; D014157:Transcription Factors