The broad objectives of the proposed research are to elucidate the chemical steps in a proposed pathway defining the role of catalase-peroxidase (KatG) in the mechanism of action of isoniazid (INH), an anti-tuberculosis antibiotic. This pro-drug has been in use for over 50 years to treat TB yet a complete picture of its mechanism of action is still not clearly understood. The continuing emergence of INH-resistant TB infection throughout the world demands continued vigilance in learning about antibiotic function and the origins of widespread antibiotic resistance. The investigation of the structure and catalytic function of M. tuberculosis KatG is central to the proposed research as this enzyme is responsible for """"""""activation"""""""" of the drug and production of a unique inhibitor of another key enzyme, an enoyl reductase required for mycolic acid biosynthesis and cell wall integrity in pathogenic mycobacteria. This inhibitor is an acyl-NADH adduct generated through oxidative reactions catalyzed by KatG. The mechanism and kinetics of the reactions leading to production of the adduct are among the aims in the proposed research. Hypotheses about the potential role of heme-based catalysis and catalysis by a tyrosyl radical in KatG will be tested. The participation of both INH and adenine dinucleotides as substrates will be investigated using optical-stopped flow spectrophotometry and rapid freeze-quench electron paramagnetic resonance (EPR). Results for the wild-type enzyme will be compared to those for several mutant enzymes known to confer 1NH resistance to identify the origins of drug resistance in KatG enzymology. Other tools used in the proposed research to study enzyme structure and catalytic mechanism include resonance Raman spectroscopy and x-ray crystallography. The technique of isothermal titration calorimetry is also being applied to study the requirements in the KatG enzyme and in the INH molecule for high affinity binding of the drug. The research will provide new insights into a poorly understood but critically important anti-TB agent.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI060014-02
Application #
7008163
Study Section
Physical Biochemistry Study Section (PB)
Program Officer
Goldman, Robert C
Project Start
2005-02-01
Project End
2010-01-31
Budget Start
2006-02-01
Budget End
2007-01-31
Support Year
2
Fiscal Year
2006
Total Cost
$373,511
Indirect Cost
Name
Brooklyn College
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
620127691
City
New York
State
NY
Country
United States
Zip Code
11210
Zhao, Xiangbo; Khajo, Abdelahad; Jarrett, Sanchez et al. (2012) Specific function of the Met-Tyr-Trp adduct radical and residues Arg-418 and Asp-137 in the atypical catalase reaction of catalase-peroxidase KatG. J Biol Chem 287:37057-65
Martinez, Alberto; Suarez, Javier; Shand, Tiffany et al. (2011) Interactions of arene-Ru(II)-chloroquine complexes of known antimalarial and antitumor activity with human serum albumin (HSA) and transferrin. J Inorg Biochem 105:39-45
Zhao, Xiangbo; Suarez, Javier; Khajo, Abdelahad et al. (2010) A radical on the Met-Tyr-Trp modification required for catalase activity in catalase-peroxidase is established by isotopic labeling and site-directed mutagenesis. J Am Chem Soc 132:8268-9
Zhao, Xiangbo; Yu, Shengwei; Ranguelova, Kalina et al. (2009) Role of the oxyferrous heme intermediate and distal side adduct radical in the catalase activity of Mycobacterium tuberculosis KatG revealed by the W107F mutant. J Biol Chem 284:7030-7
Colangeli, R; Haq, A; Arcus, V L et al. (2009) The multifunctional histone-like protein Lsr2 protects mycobacteria against reactive oxygen intermediates. Proc Natl Acad Sci U S A 106:4414-8
Suarez, Javier; Ranguelova, Kalina; Jarzecki, Andrzej A et al. (2009) An oxyferrous heme/protein-based radical intermediate is catalytically competent in the catalase reaction of Mycobacterium tuberculosis catalase-peroxidase (KatG). J Biol Chem 284:7017-29
Suarez, Javier; Ranguelova, Kalina; Schelvis, Johannes P M et al. (2009) Antibiotic resistance in Mycobacterium tuberculosis: peroxidase intermediate bypass causes poor isoniazid activation by the S315G mutant of M. tuberculosis catalase-peroxidase (KatG). J Biol Chem 284:16146-55
Ranguelova, Kalina; Suarez, Javier; Magliozzo, Richard S et al. (2008) Spin trapping investigation of peroxide- and isoniazid-induced radicals in Mycobacterium tuberculosis catalase-peroxidase. Biochemistry 47:11377-85
Ranguelova, Kalina; Suarez, Javier; Metlitsky, Leonid et al. (2008) Impact of distal side water and residue 315 on ligand binding to ferric Mycobacterium tuberculosis catalase-peroxidase (KatG). Biochemistry 47:12583-92
Hirota, Shun; Kawahara, Takumi; Beltramini, Mariano et al. (2008) Molecular basis of the Bohr effect in arthropod hemocyanin. J Biol Chem 283:31941-8

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