A cooperative oxygen binding hemoglobin from Mycobacterium tuberculosis. Stabilization of heme ligands by a distal tyrosine residue

The homodimeric hemoglobin (HbN) from Mycobacterium tuberculosis displays an extremely high oxygen binding affinity and cooperativity. Sequence alignment with other hemoglobins suggests that the proximal F8 ligand is histidine, the distal E7 residue is leucine, and the B10 position is occupied by ty...

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Bibliographic Details
Published in:The Journal of biological chemistry 2000-01, Vol.275 (3), p.1679-1684
Main Authors: Yeh, S R, Couture, M, Ouellet, Y, Guertin, M, Rousseau, D L
Format: Article
Language:English
Subjects:
Carbon Monoxide - chemistry
Heme - chemistry
Hemoglobins - chemistry
Hydrogen - chemistry
Hydroxides - chemistry
Ligands
Models, Chemical
Mycobacterium tuberculosis
Mycobacterium tuberculosis - chemistry
Oxygen - chemistry
Recombinant Proteins - chemistry
Spectrum Analysis, Raman
Tyrosine - chemistry
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Summary:The homodimeric hemoglobin (HbN) from Mycobacterium tuberculosis displays an extremely high oxygen binding affinity and cooperativity. Sequence alignment with other hemoglobins suggests that the proximal F8 ligand is histidine, the distal E7 residue is leucine, and the B10 position is occupied by tyrosine. To determine how these heme pocket residues regulate the ligand binding affinities and physiological functions of HbN, we have measured the resonance Raman spectra of the O(2), CO, and OH(-) derivatives of the wild type protein and the B10 Tyr --> Leu and Phe mutants. Taken together these data demonstrate a unique distal environment in which the heme bound ligands strongly interact with the B10 tyrosine residue. The implications of these data on the physiological functions of HbN and another heme-containing protein, cytochrome c oxidase, are considered.
ISSN:0021-9258
DOI:10.1074/jbc.275.3.1679