Cloning and Expression of Two Novel Hemin Binding Protein Genes from Treponema denticola

These results indicate that all of the strains of T. denticola tested, including the one used by Scott et al in identifying a 47-kDa hemin binding protein, have the hbpA gene and that the gene organization around hbpA is identical in all T. denticola strains

Xiaoping Xu

2002

Scholarcy highlights

  • There is mounting evidence for the roles of several oral anaerobic spirochetes in periodontal disease, with the best characterized species being Treponema denticola
  • Previous studies have shown that T. denticola contains at least two hemin binding molecules: a 47-kDa constitutively produced hemin binding protein from strain ATCC 35405 and a 44-kDa hemin binding protein, which is up-regulated under iron-restricted growth, that is found in strains GM-1, MS-25, ATCC 33520, and ATCC 33404
  • All of the T. denticola strains had a 2.9-kb band with the orf1 probe and a 2.3-kb band with the hbpB probe, while T. pectinovorum, T. socranskii, and E. coli gave no signal with either probe. These results indicate that all of the strains of T. denticola tested, including the one used by Scott et al in identifying a 47-kDa hemin binding protein, have the hbpA gene and that the gene organization around hbpA is identical in all T. denticola strains
  • The T. denticola HbpA is not homologous to any other hemin binding protein, nor does it share stretches of significant sequence identity with iron acquisition proteins from other bacteria
  • The inability to find a “hemin binding motif” in HbpA is not surprising, since no such motif has been identified in hemin binding proteins from other bacteria, despite the fact that most of the hemin binding proteins from other bacteria do show homology with each other
  • The 44-kDa outer membrane proteins is a novel hemin binding protein, which is likely to serve as a hemin receptor for T. denticola
  • Denticola strains tested: all six strains tested hybridized to the exact same size of HindIII fragments containing orf1, hbpA, and hbpB

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