Reactions of Mycobacterium tuberculosis Truncated Hemoglobin O with Ligands Reveal a Novel Ligand-Inclusive Hydrogen Bond Network

Truncated hemoglobin O (trHbO) is one of two trHbs in Mycobacterium tuberculosis. Remarkably, trHbO possesses two novel distal residues, in addition to the B10 tyrosine, that may be important in ligand binding. These are the CD1 tyrosine and G8 tryptophan. Here we investigate the reactions of trHbO...

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Bibliographic Details
Published in:Biochemistry (Easton) 2003-05, Vol.42 (19), p.5764-5774
Main Authors: Ouellet, Hugues, Juszczak, Laura, Dantsker, David, Samuni, Uri, Ouellet, Yannick H, Savard, Pierre-Yves, Wittenberg, Jonathan B, Wittenberg, Beatrice A, Friedman, Joel M, Guertin, Michel
Format: Article
Language:English
Subjects:
Bacterial Proteins - chemistry
Bacterial Proteins - genetics
Bacterial Proteins - metabolism
Binding Sites
Carbon Monoxide - metabolism
Heme - chemistry
Hemoglobins - chemistry
Hemoglobins - genetics
Hemoglobins - metabolism
Hydrogen Bonding
Kinetics
Ligands
Models, Molecular
Mutagenesis, Site-Directed
Mycobacterium tuberculosis - genetics
Mycobacterium tuberculosis - metabolism
Nitric Oxide - metabolism
Oxygen - metabolism
Recombinant Proteins - chemistry
Recombinant Proteins - genetics
Recombinant Proteins - metabolism
Truncated Hemoglobins
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Summary:Truncated hemoglobin O (trHbO) is one of two trHbs in Mycobacterium tuberculosis. Remarkably, trHbO possesses two novel distal residues, in addition to the B10 tyrosine, that may be important in ligand binding. These are the CD1 tyrosine and G8 tryptophan. Here we investigate the reactions of trHbO and mutants using stopped-flow spectrometry, flash photolysis, and UV-enhanced resonance Raman spectroscopy. A biphasic kinetic behavior is observed for combination and dissociation of O2 and CO that is controlled by the B10 and CD1 residues. The rate constants for combination (
ISSN:0006-2960
1520-4995
DOI:10.1021/bi0270337