Characterization of two genes encoding distinct transferrin-binding proteins in different Actinobacillus pleuropneumoniae isolates

Abstract

The gene encoding the ActinobaciUus pleuropneumoniae serotype 1 transferrin-binding protein (tfbA) was cloned, and the carboxy-terminal 70%o of the protein was expressed as an aggregate protein in Escherichia coli.The nucleotide sequences of the aJbA genes from A. pleuropneumoniae serotypes 7 (G.-F. Gerlach, C. Anderson, A. A. Potter, S. Klashinsky, and P. J. Willson, Infect. Immun. 60:892-898, 1992) and 1 were determined, and a comparison revealed that they had 65% sequence identity. The deduced amino acid sequences showed a sequence agreement of 55%, and both proteins possessed a lipoprotein-like signal sequence. The serotype 1 TfbA protein had a predicted molecular mass of 65 kDa, compared with 60 kDa for the serotype 7 TfbA protein, and both proteins were immunologically distinct as assessed in a competitive enzyme-linked immunosorbent assay. Southern hybridization and Western blot (immunoblot) analysis of the 13 A. pleuropneumoniae type strains revealed that serotypes 2, 3, 4, 8, 9, 10, and 11 encode and express a TfbA protein highly homologous to that ofA. pleuropneumoniae serotype 7 whereas the TfbA proteins and the encoding genes of serotypes 6 and 12 were highly homologous to that found in A. pleuropneumoniae serotype 1. The aJbA genes of A. pleuropneumoniae serotypes 5A and 5B were recognized, under medium-stringency hybridization conditions, by the A. pleuropneumoniae serotype 1-derived tJbA probe, and the respective proteins were weakly reactive with the antibody raised against the A. pleuropneumoniae serotype 7 TfbA protein.

Antigenic relationships of transferrin-binding proteins from Neisseria meningitisis, N. gonorrhoeae and Haemophilus influenzae: Cross-reactivity of antibodies to NH2-terminal peptides

“…Interestingly, the complete sequence of the gonococcal TBP1 has domains homologous to Escherichia coli TonB-dependent outer membrane receptors, suggesting that the TBP1 molecule is a member of a class of proteins that serve as specific receptors for necessary nutrients such as iron and vitamin B~2 [13]. The deduced amino acid sequences of two distinct transferrin-binding proteins (TfbA) from different isolates of Actinobacillus pleuropneumoniae were also reported recently [14]. A comparison of the first 13 amino acids in the NH2-terminal of meningococcal TBP2 with those in the predicted NH2-terminus of the TfbA proteins shows about 60% sequence identity; the TfbA proteins possess a lipoprotein-like signal sequence.…”

Cloning and expression of the Haemophilus influenzae transferrin receptor genes

“…2). When the Tbp2 sequences of the eight H. influenzae strains were compared with those of the N. meningitidis strains B16B6 and M982 (Legrain et al, 1993), N. gonorrhoeae strain FA19 (Anderson et al, 1994) and A. pleuropneumoniae strains 205 and 37 (Gerlach et al, 1992b), minimal similarity was found (Fig. 3).…”

“…Comparison of the Tbp2 amino acid sequences of H. influenzae strains Eagan (MinnA sequence is identical), DL63, PAK 12085, SB12, SB29, SB30, and SB32, N. meningitidis strains B16B6 and M982 (Legrain et al, 1993), N. gonorrhoeae strain FA19 (Anderson et al, 1994), and A. pleuropneumoniae strains 205 and 37 (Gerlach et al, 1992b). The single letter amino acid code is used and stop codons are designated by asterisks.…”

The Neisseria meningitidis haemoglobin receptor: its role in iron utilization and virulence

“…1992), Pathogenic bacteria have adapted to this iron-limiting environment by developing highly specific and effective iron-assimilation systems. A large number of these bacteria secrete siderophores -smail, non-protein iron cheiatots which, because ot their extvemety high aftinity tor iron(ill), scavenge trace amounts of iron(lll) from the environment and shuttle the iron back to the bacterial cell (Baggs and Neilands, 1987;Braun and Hantke, 1991), Some bacteriai pathogens, like neisseriae (Archibald and DeVoe, 1979;Mickelsen et at., 1982: Dyer ef a/., 1987, Haetnoptiilus inftuenzae (Coulton and Pang, 1983;Schtyvers, 1988;Jarosik et at.. 1994), Vibrio ctiolerae (Stoebner and Payne, 1988;Henderson and Payne, 1994), yersiniae (Stojiljkovic and Hantke, 1992) and Actinobaciltus ptearopneumotiiae (Gerlach et at., 1992) have evolved more sophisticated mechanisms to sequester iron from the host. These pathogens can directly bind the host's ironbinding proteins such as lactoferrin, transferrin, and haem-containing compounds, and use them as sole sources of iron, Neisseriae meningitidis is one of the leading causes of bacterial meningitis in children and heaithy adults in the worid.…”