Pathogenic bacteria of the genus Neisseria have a siderophore-independent iron-uptake system reliant on a direct interaction between the bacterial cell and human transferrin (hTf), a serum protein. In the meningococcus, this uptake system is dependent on two surface-exposed, transferrin-binding proteins (Tbps), TbpA and TbpB. TbpA is highly conserved among meningococcal strains, and is thought to be a porin-like integral protein that functions as a gated channel for the passage of iron into the periplasm. TbpB is more variable in size, lipidated and fully surface-exposed. Given its location on the cell surface, its role in pathogenicity and interstrain sequence conservation, TbpA is currently being regarded for inclusion in a meningococcal vaccine effective against all serogroups. This requires gaining knowledge of the ligand—receptor interactions. In the present study we have optimized a procedure for obtaining purified, functionally active recombinant TbpA at a level and stability necessary for the initiation of such studies.
Abbreviations used: HRP, horseradish peroxidase; hTf, human transferrin; mTf, murine transferrin; pTf, pig transferrin, rTbpA, recombinant TbpA; Tbp, transferrin-binding protein.
Present address: Laboratory of Molecular Biology, NIDDK, National Institutes of Health, 50 South Drive, Bethesda, MD 20892-8030, U.S.A.