The Neisseria meningitidis haemoglobin receptor: its role in iron utilization and virulence.
The Neisseria meningitidis haemoglobin receptor gene, hmbR, was cloned by complementation in a porphyrin-requiring Escherichia coli mutant. hmbR encodes an 89.5 kDa outer membrane protein which shares amino acid homology with the TonB-dependent receptors of Gram-negative bacteria. HmbR had the highest similarity to Neisseria transferrin and lactoferrin receptors. The utilization of haemoglobin as an iron source required internalization of the haemin moiety by the cell. The mechanism of haemin internalization via the haemoglobin receptor was TonB-dependent in E. coli. A N. meningitidis hmbR mutant was unable to use haemoglobin but could still use haemin as a sole iron source. The existence of a second N. meningitidis receptor gene, specific for haemin, was shown by the isolation of cosmids which did not hybridize with the hmbR probe, but which were able to complement an E. coli hemA aroB mutant on haemin-supplemented plates. The N. meningitidis hmbR mutant was attenuated in an infant rat model for meningococcal infection, indicating that haemoglobin utilization is important for N. meningitidis virulence.
Stojiljkovic
I
I
Department of Molecular Microbiology and Immunology, Oregon Health Sciences University, Portland 97201, USA.
Hwa
V
V
de Saint Martin
L
L
O'Gaora
P
P
Nassif
X
X
Heffron
F
F
So
M
M
D000445:Aldehyde Oxidoreductases / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D001483:Base Sequence; D003001:Cloning, Molecular; D003360:Cosmids; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D006427:Hemin / Q000378:metabolism; D007501:Iron / Q000378:metabolism*; D008565:Membrane Proteins / Q000502:physiology; D008585:Meningitis, Meningococcal / Q000382:microbiology; D008969:Molecular Sequence Data; D009345:Neisseria meningitidis / Q000378:metabolism* / Q000472:pathogenicity; D051381:Rats; D011917:Rats, Inbred Lew; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D011990:Receptors, Transferrin / Q000737:chemistry; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D014774:Virulence
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C052874:ExbB protein, E coli; C094109:HmbR protein, Neisseria meningitidis; D008565:Membrane Proteins; D011956:Receptors, Cell Surface; D011990:Receptors, Transferrin; C038340:lactoferrin receptors; C057616:tonB protein, Bacteria; C489181:tonB protein, E coli; C060790:exbD protein, E coli; D006427:Hemin; D007501:Iron; D000445:Aldehyde Oxidoreductases; C067282:glutamyl tRNA reductase