Identification of an outer-membrane haemoglobin-binding protein in Neisseria meningitidis

J Gen Microbiol. 1992 Dec;138(12):2647-56. doi: 10.1099/00221287-138-12-2647.

Abstract

Although Neisseria meningitidis can use haemoglobin as an iron source in vitro, the mechanism of haemoglobin-iron uptake is unknown. Using a biotinylated human haemoglobin probe in a solid-phase dot-binding assay, haemoglobin-binding activity was detected in total membranes derived from meningococci grown under iron-limited but not iron-sufficient conditions. In competition binding experiments, bovine and human haemoglobin could abrogate binding. In contrast, no binding inhibition was seen with ferric nitrate, protoporphyrin IX, and iron-loaded human transferrin. The ability of both haemin and catalase, a nonhaemoglobin haem-containing compound, to inhibit binding competitively suggested that the ligand recognized by the binding protein is the haem moiety. Scatchard plot analysis revealed a heterogeneous receptor population. Limited proteolysis with proteinase K abolished binding activity, suggesting a haemoglobin-protein interaction. Detection of activity in a whole-cell binding assay demonstrated that this haemin-binding protein was surface exposed. In a limited survey of meningococcal strains, the presence of haemoglobin-binding activity in all isolates indicated that expression of this binding protein is not serogroup specific.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Outer Membrane Proteins / analysis
  • Bacterial Outer Membrane Proteins / isolation & purification*
  • Bacterial Outer Membrane Proteins / metabolism
  • Bacterial Proteins*
  • Biological Transport
  • Biotin
  • Carrier Proteins / analysis
  • Carrier Proteins / isolation & purification*
  • Carrier Proteins / metabolism
  • Endopeptidase K
  • Genetic Variation
  • Hemoglobins / metabolism*
  • Iron / metabolism*
  • Iron / pharmacology
  • Molecular Probes
  • Neisseria meningitidis / growth & development
  • Neisseria meningitidis / metabolism*
  • Receptors, Transferrin / biosynthesis
  • Serine Endopeptidases / pharmacology
  • Subcellular Fractions / chemistry

Substances

  • Bacterial Outer Membrane Proteins
  • Bacterial Proteins
  • Carrier Proteins
  • Hemoglobins
  • Molecular Probes
  • Receptors, Transferrin
  • hemoglobin-binding protein, bacteria
  • Biotin
  • Iron
  • Serine Endopeptidases
  • Endopeptidase K