Truncated hemoglobins (trHbs) are a recently discovered class of small oxygen-binding protohemeproteins, widely distributed in prokaryotes. Many occur in bacteria pathogenic to man (e.g. Mycobacterium tuberculosis (TB), Mycobacterium avium, Mycobacterium leprae, Cornybacterium diphtheriae, Bordetella pertussis, Legionella pneumophila, Staphylococcus aureus and Bacillus anthracis). This project will focus on trHbN and trHbO, the two trHbs from TB. TrHbN protects aerobic respiration from the inhibitory action of nitric oxide and enhances infectivity. The function oftrHbO is essential for bacterial growth. Since trHbs are not present in man, this makes them potential drug targets. The emphasis of this project is on probing those unusual biophysical properties of these two trHbs that are hypothesized to be the basis for the unusual functionalities that are of potential biomedical significance. Several specific aims are designed to expose the nature and significance of the hydrogen bonding network found in the distal hempocket and of the large apolar tunnel that links the solvent to the ligand binding site at the heme. To achieve in depth insight into how the hydrogen bonding network and the apolar tunnel functioning of these two important proteins, several techniques will be used including photolysis, stopped-flow spectrometry, vibrational spectroscopy (FTIR, UV and visible resonance Raman), structure analysis (X-ray diffraction, NMR), site directed mutagenesis and conformational trapping and kinetics of ligand rebinding. In parallel with this part of the overall project, genetic and molecular biological approaches will be used to correlate the biophysical results with the in vivo functional studies. ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI052258-03
Application #
7083546
Study Section
Molecular and Cellular Biophysics Study Section (BBCA)
Program Officer
Jacobs, Gail G
Project Start
2004-07-15
Project End
2008-06-30
Budget Start
2006-07-01
Budget End
2007-06-30
Support Year
3
Fiscal Year
2006
Total Cost
$366,919
Indirect Cost
Name
Albert Einstein College of Medicine
Department
Physiology
Type
Schools of Medicine
DUNS #
110521739
City
Bronx
State
NY
Country
United States
Zip Code
10461
Ouellet, Yannick H; Daigle, Richard; Lague, Patrick et al. (2008) Ligand binding to truncated hemoglobin N from Mycobacterium tuberculosis is strongly modulated by the interplay between the distal heme pocket residues and internal water. J Biol Chem 283:27270-8
Bolli, Alessandro; Ciaccio, Chiara; Coletta, Massimo et al. (2008) Ferrous Campylobacter jejuni truncated hemoglobin P displays an extremely high reactivity for cyanide - a comparative study. FEBS J 275:633-45
Pesce, Alessandra; Milani, Mario; Nardini, Marco et al. (2008) Mapping heme-ligand tunnels in group I truncated(2/2) hemoglobins. Methods Enzymol 436:303-15
Pesce, Alessandra; Nardini, Marco; Milani, Mario et al. (2007) Protein structure in the truncated (2/2) hemoglobin family. IUBMB Life 59:535-41
Samuni, Uri; Roche, Camille J; Dantsker, David et al. (2007) Conformational dependence of hemoglobin reactivity under high viscosity conditions: the role of solvent slaved dynamics. J Am Chem Soc 129:12756-64
Samuni, Uri; Dantsker, David; Roche, Camille J et al. (2007) Ligand recombination and a hierarchy of solvent slaved dynamics: the origin of kinetic phases in hemeproteins. Gene 398:234-48
Ouellet, Hugues; Milani, Mario; LaBarre, Marie et al. (2007) The roles of Tyr(CD1) and Trp(G8) in Mycobacterium tuberculosis truncated hemoglobin O in ligand binding and on the heme distal site architecture. Biochemistry 46:11440-50
Nardini, Marco; Pesce, Alessandra; Milani, Mario et al. (2007) Protein fold and structure in the truncated (2/2) globin family. Gene 398:2-11
Ouellet, Hugues; Ranguelova, Kalina; Labarre, Marie et al. (2007) Reaction of Mycobacterium tuberculosis truncated hemoglobin O with hydrogen peroxide: evidence for peroxidatic activity and formation of protein-based radicals. J Biol Chem 282:7491-503
Roche, Camille J; Dantsker, David; Samuni, Uri et al. (2006) Nitrite reductase activity of sol-gel-encapsulated deoxyhemoglobin. Influence of quaternary and tertiary structure. J Biol Chem 281:36874-82

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