Oxidative release of nitrite from 2-nitrotoluene by a three-component enzyme system from Pseudomonas sp. strain JS42.
Pseudomonas sp. strain JS42 utilizes 2-nitrotoluene (2NT) as the sole source of carbon and energy for growth. Intact cells catalyze the oxidation of 2NT to 3-methylcatechol and nitrite in a reaction that requires molecular oxygen. Cell extracts oxidized 2NT to 3-methylcatechol and nitrite in the presence of NAD(P)H and ferrous iron. Ion-exchange chromatography yielded three protein fractions (A, B, and C) which were all required for the oxidation of 2NT to 3-methylcatechol and nitrite. Component B (reductase2NT) catalyzed a NAD(P)H-dependent reduction of cytochrome c. Solutions of component A (ISP2NT) were brown and showed absorption maxima at 458 and 324 nm. Two major bands with M(r)s 52,500 and 28,000 were observed when ISP2NT was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Component C could be replaced by ferredoxin NAP from the Pseudomonas putida NCIB 9816-4 naphthalene dioxygenase system and was given the designation ferredoxin2NT. Experiments with 18O2 showed that both oxygen atoms were added to the aromatic ring of 2NT to yield 3-methylcatechol. The enzyme is a new multicomponent enzyme system which we have designated 2NT 2,3-dioxygenase.
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Department of Microbiology, University of Iowa, Iowa City 52242.
Gibson
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DT
Spain
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JC
D001673:Biodegradation, Environmental; D002396:Catechols / Q000737:chemistry; D002852:Chromatography, Ion Exchange; D008954:Models, Biological; D009097:Multienzyme Complexes / Q000378:metabolism*; D009245:NADH Dehydrogenase / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D010105:Oxygenases / Q000378:metabolism*; D011549:Pseudomonas / Q000201:enzymology / Q000378:metabolism*; D013053:Spectrophotometry; D013379:Substrate Specificity; D014050:Toluene / Q000031:analogs & derivatives* / Q000378:metabolism
D002396:Catechols; D009097:Multienzyme Complexes; D009573:Nitrites; C031136:3-methylcatechol; D014050:Toluene; C029955:2-nitrotoluene; D010105:Oxygenases; D009245:NADH Dehydrogenase; D010100:Oxygen