title: Cloning and sequencing of a Bordetella pertussis serum resistance locus.
abstract: We have characterized a new virulence factor in Bordetella pertussis: serum resistance. Compared with Escherichia coli HB101, wild-type B. pertussis was relatively resistant to classical-pathway, complement-dependent killing by normal human serum. However, a mutant of B. pertussis (BPM2041) which is less virulent in mice and which has Tn5 lac inserted in a previously uncharacterized bvg-regulated gene was found to be at least 10-fold more susceptible to serum killing than the wild type. We have named this locus brk, for Bordetella resistance to killing. We have cloned and sequenced the brk locus, and it encodes two divergently transcribed open reading frames (ORFs), termed BrkA and BrkB. Both ORFs are necessary for serum resistance. Within the 300 bases which separate the two ORFs and upstream of each ORF are putative sites for BvgA binding. BrkA shows 29% identity to pertactin and has two RGD motifs in addition to a conserved proteolytic processing site and an outer membrane targeting signal. Like pertactin, BrkA is involved in adherence and invasion. Despite the similarities, a pertactin mutant was found to be not as sensitive to serum killing as the BrkA or BrkB mutants. BrkB is similar to ORFs in E. coli and Mycobacterium leprae and displays domains of homology to various transporters. On the basis of its hydropathy profile, BrkB is predicted to be a cytoplasmic membrane protein. By Southern blot, brk sequences were found in Bordetella bronchiseptica and Bordetella parapertussis but not in Bordetella avium.
authors.affiliation: Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati, Ohio 45267.
authors.forename: R C
authors.initials: RC
authors.lastname: Fernandez
authors.forename: A A
authors.initials: AA
authors.lastname: Weiss
mesh_terms: D000595:Amino Acid Sequence; D001422:Bacterial Adhesion; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000235:genetics*; D001426:Bacterial Proteins; D001483:Base Sequence; D001770:Blood Bactericidal Activity; D001886:Bordetella pertussis / Q000235:genetics* / Q000472:pathogenicity; D018834:Chaperonin 60 / Q000235:genetics; D018833:Chaperonins / Q000235:genetics; D003001:Cloning, Molecular; D003171:Complement Pathway, Classical; D005798:Genes, Bacterial; D006801:Humans; D066298:In Vitro Techniques; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D016254:Mutagenesis, Insertional; D015183:Restriction Mapping; D013045:Species Specificity; D010566:Virulence Factors, Bordetella
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; C090007:BrkA protein, Bordetella pertussis; C090008:BrkB protein, Bordetella pertussis; D018834:Chaperonin 60; D008565:Membrane Proteins; D010566:Virulence Factors, Bordetella; C068929:pertactin; D018833:Chaperonins