title: Nitrite elimination and hydrolytic ring cleavage in 2,4,6-trinitrophenol (picric acid) degradation.
abstract: Two hydrogenation reactions in the initial steps of degradation of 2,4,6-trinitrophenol produce the dihydride Meisenheimer complex of 2,4,6-trinitrophenol. The npdH gene (contained in the npd gene cluster of the 2,4,6-trinitrophenol-degrading strain Rhodococcus opacus HL PM-1) was shown here to encode a tautomerase, catalyzing a proton shift between the aci-nitro and the nitro forms of the dihydride Meisenheimer complex of 2,4,6-trinitrophenol. An enzyme (which eliminated nitrite from the aci-nitro form but not the nitro form of the dihydride complex of 2,4,6-trinitrophenol) was purified from the 2,4,6-trinitrophenol-degrading strain Nocardioides simplex FJ2-1A. The product of nitrite release was the hydride Meisenheimer complex of 2,4-dinitrophenol, which was hydrogenated to the dihydride Meisenheimer complex of 2,4-dinitrophenol by the hydride transferase I and the NADPH-dependent F(420) reductase from strain HL PM-1. At pH 7.5, the dihydride complex of 2,4-dinitrophenol is protonated to 2,4-dinitrocyclohexanone. A hydrolase was purified from strain FJ2-1A and shown to cleave 2,4-dinitrocyclohexanone hydrolytically to 4,6-dinitrohexanoate.
authors.affiliation: Institute of Microbiology, University of Stuttgart, 70569 Stuttgart, Germany.
authors.forename: Klaus W
authors.initials: KW
authors.lastname: Hofmann
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Knackmuss
authors.forename: Gesche
authors.initials: G
authors.lastname: Heiss
mesh_terms: D019297:2,4-Dinitrophenol / Q000378:metabolism; D000192:Actinomycetales / Q000201:enzymology* / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D001673:Biodegradation, Environmental; D006867:Hydrolases / Q000737:chemistry / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009573:Nitrites / Q000378:metabolism*; D010851:Picrates / Q000737:chemistry / Q000378:metabolism*; D012240:Rhodococcus / Q000201:enzymology* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D009573:Nitrites; D010851:Picrates; C005858:picric acid; D006867:Hydrolases; D019297:2,4-Dinitrophenol