Disease relevance of fhaB

• The nucleotide sequence of the structural gene for filamentous haemagglutinin (FHA), fhaB, a crucial adherence factor for Bordetella pertussis, has been determined [1].
• To identify antigenic regions of FHA, phage display libraries constructed by using random fragments of the 10-kbp EcoRI fragment of B. pertussis fhaB were affinity selected with rabbit anti-FHA polyclonal antibodies [2].
• In B. pertussis cultures grown in Stainer-Scholte broth, expression of ptxA3201-cat differed from that of fhaB-cat in several respects [3].
• Activation of fhaB transcription by bvgA overexpression in E. coli is no longer repressed by environmental conditions [4].

High impact information on fhaB

• Deletion analyses suggest that fhaB and the downstream genes can be transcribed as a polycistronic operon, and primer extension analysis revealed the presence of a second promoter between fhaB and fhaD [5].
• Deletion of its structural gene, fhaB, or a Tn5 insertion in fhaA, downstream of fhaB, resulted in a FHA- and fimbriae- phenotype, although fhaB and the fim genes are not linked [5].
• The nucleotide sequence of an open reading frame that encompasses the filamentous hemagglutinin structural gene, fhaB, suggests that proteolytic processing is necessary to generate the mature 220-kDa filamentous hemagglutinin product [6].
• An internal in-frame deletion in fhaB, encompassing the RGD region, causes loss of B. pertussis-binding to ciliated eukaryotic cells, confirming a potential role for this protein in host-cell binding and infection [6].
• Binding studies indicated that this mutant protein was able to bind an oligonucleotide containing a high-affinity BvgA binding site in a manner similar to wild-type BvgA, but was defective for binding the fhaB promoter in the absence of RNA polymerase (RNAP) [7].

Biological context of fhaB

• Fusion proteins derived from various portions of the fhaB open reading frame (ORF) were used to generate polyclonal antisera [1].
• By contrast, BvgA containing the R152H substitution had wild-type phosphorylation properties but was severely defective in its ability to bind either the high-affinity BvgA binding site-containing oligonucleotide or the fhaB promoter by itself [7].
• In this study a series of lacZYA fusions containing deletions in either the fhaB or bvgA promoter regions was used to identify cis-acting regulatory regions required for bvg activation of these two genes [8].
• The regulatory regions found upstream of fhaB and bvgA which are involved in protein binding both contain the sequence TTTCCTA [8].
• Single-copy lacZYA fusions to the B. pertussis fhaB locus, which encodes the attachment factor filamentous hemagglutinin, were activated nearly 400-fold by pBR322 replicons carrying sequences that included bvg [9].

Anatomical context of fhaB

• Filamentous hemagglutinin adhesin (FHA) is important for the adherence of Bordetella pertussis to the host ciliary epithelial cells of the respiratory tract [10].

Associations of fhaB with chemical compounds

• The mutations, localized in the linker and transmitter domain of BvgS, result in increased activation of fhaB and/or in insensitivity to a modulating agent, nicotinic acid [11].

Other interactions of fhaB

• Mutations in the Bordetella pertussis bvgS gene that confer altered expression of the fhaB gene in Escherichia coli [11].
• A strain containing a mutation in fhaB was significantly less adhesive and invasive than its parent, and a prn fhaB double mutant exhibited an even greater reduction in adhesiveness and invasiveness down to levels comparable with a Vir- strain [12].
• Environmental signals that modulate expression of virulence genes in B. pertussis had a pronounced effect on bvg-mediated activation of fhaB-lacZ [9].

References