The determination of the relationship between an enzyme's three-dimensional structure and its catalytic and physiological function continues to be the long-range objective of this research program. The expanding family of flavoprotein reductases represent an appropriate and unique selection for such investigations, since they are ubiquitously distributed, mechanistically intriguing and serve critical roles in the organisms in which they are present. Examples of these pivotal roles played by flavoprotein reductases include pro- and eukaryotic oxidative stress management involving alkyl hydroperoxide reductase, NADH peroxidase, glutathione reductase and its unique homologue found only in parasitic protozoal pathogens, trypanothione reductase. Members of the flavoprotein reductase family additionally serve to detoxify mercuric salts and assist in proper protein folding by catalyzing disulfide bond formation and isomerization. The amino acid sequences of many of these enzymes are known, and the three dimensional structure of six flavoprotein reductases have been determined at high resolution. The relationship between the structure and function of trypanothione reductase will be probed by a combination of kinetic, isotopic and mutagenic approaches. To understand the role played by flavoprotein reductases enabling pathogenic bacteria to withstand the large flux of reduced oxygen species inside macrophage, two new previously unidentified flavoproteins from mycobacteria, identified as a lipoamide dehydrogenase and an unprecedented disulfide reductase will be characterized. These enzymes will be purified, their kinetic and chemical mechanisms determined, the range of reactions catalyzed examined and the genes encoding the enzymes sequenced. These studies will provide a timely and relevant characterization of the role these enzymes play in the survival of these pathogens in an oxidatively stressful environment, and could ultimately lead to the development of specific inhibitors with chemotherapeutic utility.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
2R01GM033449-13
Application #
2021998
Study Section
Biochemistry Study Section (BIO)
Project Start
1984-04-01
Project End
2001-01-31
Budget Start
1997-02-01
Budget End
1998-01-31
Support Year
13
Fiscal Year
1997
Total Cost
Indirect Cost
Name
Albert Einstein College of Medicine
Department
Biochemistry
Type
Schools of Medicine
DUNS #
009095365
City
Bronx
State
NY
Country
United States
Zip Code
10461
Argyrou, Argyrides; Vetting, Matthew W; Blanchard, John S (2004) Characterization of a new member of the flavoprotein disulfide reductase family of enzymes from Mycobacterium tuberculosis. J Biol Chem 279:52694-702
Argyrou, Argyrides; Blanchard, John S (2004) Flavoprotein disulfide reductases: advances in chemistry and function. Prog Nucleic Acid Res Mol Biol 78:89-142
Argyrou, Argyrides; Blanchard, John S (2004) Kinetic and chemical mechanism of Mycobacterium tuberculosis 1-deoxy-D-xylulose-5-phosphate isomeroreductase. Biochemistry 43:4375-84
Argyrou, Argyrides; Sun, Guangxing; Palfey, Bruce A et al. (2003) Catalysis of diaphorase reactions by Mycobacterium tuberculosis lipoamide dehydrogenase occurs at the EH4 level. Biochemistry 42:2218-28
Vetting, Matthew W; Roderick, Steven L; Yu, Michael et al. (2003) Crystal structure of mycothiol synthase (Rv0819) from Mycobacterium tuberculosis shows structural homology to the GNAT family of N-acetyltransferases. Protein Sci 12:1954-9
Argyrou, Argyrides; Blanchard, John S; Palfey, Bruce A (2002) The lipoamide dehydrogenase from Mycobacterium tuberculosis permits the direct observation of flavin intermediates in catalysis. Biochemistry 41:14580-90
Magnet, S; Lambert, T; Courvalin, P et al. (2001) Kinetic and mutagenic characterization of the chromosomally encoded Salmonella enterica AAC(6')-Iy aminoglycoside N-acetyltransferase. Biochemistry 40:3700-9
Argyrou, A; Blanchard, J S (2001) Mycobacterium tuberculosis lipoamide dehydrogenase is encoded by Rv0462 and not by the lpdA or lpdB genes. Biochemistry 40:11353-63
Patel, M P; Blanchard, J S (2001) Mycobacterium tuberculosis mycothione reductase: pH dependence of the kinetic parameters and kinetic isotope effects. Biochemistry 40:5119-26
Barlow, J N; Blanchard, J S (2000) Enzymatic synthesis of UDP-(3-deoxy-3-fluoro)-D-galactose and UDP-(2-deoxy-2-fluoro)-D-galactose and substrate activity with UDP-galactopyranose mutase. Carbohydr Res 328:473-80

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