title: Chemoselective nitro group reduction and reductive dechlorination initiate degradation of 2-chloro-5-nitrophenol by Ralstonia eutropha JMP134.
abstract: Ralstonia eutropha JMP134 utilizes 2-chloro-5-nitrophenol as a sole source of nitrogen, carbon, and energy. The initial steps for degradation of 2-chloro-5-nitrophenol are analogous to those of 3-nitrophenol degradation in R. eutropha JMP134. 2-Chloro-5-nitrophenol is initially reduced to 2-chloro-5-hydroxylaminophenol, which is subject to an enzymatic Bamberger rearrangement yielding 2-amino-5-chlorohydroquinone. The chlorine of 2-amino-5-chlorohydroquinone is removed by a reductive mechanism, and aminohydroquinone is formed. 2-Chloro-5-nitrophenol and 3-nitrophenol induce the expression of 3-nitrophenol nitroreductase, of 3-hydroxylaminophenol mutase, and of the dechlorinating activity. 3-Nitrophenol nitroreductase catalyzes chemoselective reduction of aromatic nitro groups to hydroxylamino groups in the presence of NADPH. 3-Nitrophenol nitroreductase is active with a variety of mono-, di-, and trinitroaromatic compounds, demonstrating a relaxed substrate specificity of the enzyme. Nitrosobenzene serves as a substrate for the enzyme and is converted faster than nitrobenzene.
authors.affiliation: Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik, D-70569 Stuttgart, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Schenzle
authors.forename: H
authors.initials: H
authors.lastname: Lenke
authors.forename: J C
authors.initials: JC
authors.lastname: Spain
authors.forename: H J
authors.initials: HJ
authors.lastname: Knackmuss
mesh_terms: D001673:Biodegradation, Environmental; D020118:Cupriavidus necator / Q000254:growth & development / Q000378:metabolism*; D009574:Nitro Compounds / Q000378:metabolism; D009596:Nitrophenols / Q000378:metabolism*; D009601:Nitroreductases / Q000378:metabolism*; D009603:Nitroso Compounds / Q000378:metabolism; D010084:Oxidation-Reduction; D013379:Substrate Specificity
chemical_list: D009574:Nitro Compounds; D009596:Nitrophenols; D009603:Nitroso Compounds; D009601:Nitroreductases; C049017:3-nitrophenol; C012456:nitrosobenzene