Catalase-peroxidases (KatG) exhibit NADH oxidase activity.
Catalase-peroxidases (KatG) produced by Burkholderia pseudomallei, Escherichia coli, and Mycobacterium tuberculosis catalyze the oxidation of NADH to form NAD+ and either H2O2 or superoxide radical depending on pH. The NADH oxidase reaction requires molecular oxygen, does not require hydrogen peroxide, is not inhibited by superoxide dismutase or catalase, and has a pH optimum of 8.75, clearly differentiating it from the peroxidase and catalase reactions with pH optima of 5.5 and 6.5, respectively, and from the NADH peroxidase-oxidase reaction of horseradish peroxidase. B. pseudomallei KatG has a relatively high affinity for NADH (Km=12 microm), but the oxidase reaction is slow (kcat=0.54 min(-1)) compared with the peroxidase and catalase reactions. The catalase-peroxidases also catalyze the hydrazinolysis of isonicotinic acid hydrazide (INH) in an oxygen- and H2O2-independent reaction, and KatG-dependent radical generation from a mixture of NADH and INH is two to three times faster than the combined rates of separate reactions with NADH and INH alone. The major products from the coupled reaction, identified by high pressure liquid chromatography fractionation and mass spectrometry, are NAD+ and isonicotinoyl-NAD, the activated form of isoniazid that inhibits mycolic acid synthesis in M. tuberculosis. Isonicotinoyl-NAD synthesis from a mixture of NAD+ and INH is KatG-dependent and is activated by manganese ion. M. tuberculosis KatG catalyzes isonicotinoyl-NAD formation from NAD+ and INH more efficiently than B. pseudomallei KatG.
Department of Microbiology, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada.
Rahul
R
Singh
Ben
B
Wiseman
Taweewat
T
Deemagarn
Lynda J
LJ
Donald
Harry W
HW
Duckworth
Xavi
X
Carpena
Ignacio
I
Fita
Peter C
PC
Loewen
D001426:Bacterial Proteins / Q000737:chemistry*; D001665:Binding Sites; D016957:Burkholderia pseudomallei / Q000378:metabolism; D002374:Catalase / Q000737:chemistry* / Q000378:metabolism; D002384:Catalysis; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D029968:Escherichia coli Proteins / Q000737:chemistry*; D006834:Hydrazines / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007477:Ions; D007538:Isoniazid / Q000737:chemistry; D007700:Kinetics; D013058:Mass Spectrometry; D008956:Models, Chemical; D008958:Models, Molecular; D009097:Multienzyme Complexes / Q000737:chemistry*; D009243:NAD / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000737:chemistry*; D010100:Oxygen / Q000378:metabolism; D009195:Peroxidase / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D013997:Time Factors
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D006834:Hydrazines; D007477:Ions; D009097:Multienzyme Complexes; D009243:NAD; C029424:hydrazine; D006861:Hydrogen Peroxide; D002374:Catalase; C051253:katG protein, E coli; C480353:katG protein, Mycobacterium tuberculosis; D009195:Peroxidase; C023107:NADH oxidase; D009247:NADH, NADPH Oxidoreductases; D010100:Oxygen; D007538:Isoniazid