title: Isolation and characterization of the haemin-binding proteins from Neisseria meningitidis.
abstract: The mechanism of haem-iron acquisition in Neisseria meningitidis is poorly understood. Using haemin-agarose in a batch affinity chromatography method, two haemin-binding proteins of 97 and 50 kDa were isolated from total membranes derived from Neisseria meningitidis B16B6 grown under iron-deficient but not under iron-replete conditions. No binding proteins were affinity-purified when total membranes underwent limited proteolysis with trypsin, suggesting a haem-protein interaction. When biotinylated human haemoglobin was used as the affinity ligand, proteins of identical molecular mass were isolated. Detection of haemin-binding proteins in a whole cell binding assay demonstrated a surface-exposed location. Competitive binding studies indicated that this haem-protein interaction was specific, because only haemin or human haemoglobin, but not cytochrome c111, protoporphyrin IX, iron-loaded human lactoferrin, iron-loaded human transferrin or Fe(NO3)3, could abrogate binding. The presence of similar haemin-binding proteins in a limited survey of clinical meningococcal strains indicated that the expression of the haemin-binding proteins is not serogroup-specific.
authors.affiliation: Department of Microbiology and Infectious Diseases, University of Calgary, Alberta, Canada.
authors.forename: B C
authors.initials: BC
authors.lastname: Lee
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000302:isolation & purification* / Q000378:metabolism; D001426:Bacterial Proteins / Q000302:isolation & purification* / Q000378:metabolism; D001667:Binding, Competitive; D002352:Carrier Proteins / Q000302:isolation & purification* / Q000378:metabolism; D002846:Chromatography, Affinity; D000081062:Heme-Binding Proteins; D006420:Hemeproteins / Q000302:isolation & purification* / Q000378:metabolism; D009345:Neisseria meningitidis / Q000737:chemistry* / Q000145:classification
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D000081062:Heme-Binding Proteins; D006420:Hemeproteins