Identification of an iron-regulated outer membrane protein of Neisseria meningitidis involved in the utilization of hemoglobin complexed to haptoglobin.
Hemoglobin complexed to the plasma protein haptoglobin can be used by Neisseria meningitidis as a source of iron to support growth in vitro. An N meningitidis mutant, DNM2E4, was generated by insertion of the mini-Tn3erm transposon into the gene coding for an 85-kDa iron-regulated outer membrane protein. Membrane proteins prepared from DNM2E4 were identical to those of the wild-type strain except that the 85-kDa protein was not produced. This mutant was unable to use hemoglobin-haptoglobin complexes as an iron source to support growth and was also impaired in the utilization of free hemoglobin. The mutant failed to bind free hemoglobin, hemoglobin-haptoglobin complexes, or apo-haptoglobin in a solid-phase dot blot assay. The 85-kDa protein was affinity purified when hemoglobin-haptoglobin complexes were used as a ligand but was not purified when free hemoglobin was used. We hypothesize that the 85-kDa iron-regulated protein is the hemoglobin-haptoglobin receptor and designate this protein Hpu (for hemoglobin-haptoglobin utilization).
Lewis
L A
LA
Department of Microbiology, School of Medicine and Biomedical Sciences, State University of New York at Buffalo 14214.
Dyer
D W
DW
D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D015153:Blotting, Western; D003001:Cloning, Molecular; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D006242:Haptoglobins / Q000378:metabolism; D006454:Hemoglobins / Q000378:metabolism; D007501:Iron / Q000494:pharmacology*; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009345:Neisseria meningitidis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D011990:Receptors, Transferrin / Q000235:genetics / Q000378:metabolism; D017421:Sequence Analysis
D001425:Bacterial Outer Membrane Proteins; D006242:Haptoglobins; D006454:Hemoglobins; D011956:Receptors, Cell Surface; D011990:Receptors, Transferrin; C027079:hemoglobin-haptoglobin receptor; D007501:Iron