title: para-Nitrophenol 4-monooxygenase and hydroxyquinol 1,2-dioxygenase catalyze sequential transformation of 4-nitrocatechol in Pseudomonas sp. strain WBC-3.
abstract: Pseudomonas sp. strain WBC-3 utilizes para-nitrophenol (PNP) as a sole source of carbon, nitrogen and energy. PnpA (PNP 4-monooxygenase) and PnpB (para-benzoquinone reductase) were shown to be involved in the initial steps of PNP catabolism via hydroquinone. We demonstrated here that PnpA also catalyzed monooxygenation of 4-nitrocatechol (4-NC) to hydroxyquinol, probably via hydroxyquinone. It was the first time that a single-component PNP monooxygenase has been shown to catalyze this conversion. PnpG encoded by a gene located in the PNP degradation cluster was purified as a His-tagged protein and identified as a hydroxyquinol dioxygenase catalyzing a ring-cleavage reaction of hydroxyquinol. Although all the genes necessary for 4-NC metabolism seemed to be present in the PNP degradation cluster in strain WBC-3, it was unable to grow on 4-NC as a sole source of carbon, nitrogen and energy. This was apparently due to the substrate's inability to trigger the expression of genes involved in degradation. Nevertheless, strain WBC-3 could completely degrade both PNP and 4-NC when PNP was used as the inducer, demonstrating its potential in bioremediation of the environment polluted by both 4-NC and PNP.
authors.affiliation: State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China.
authors.forename: Min
authors.initials: M
authors.lastname: Wei
authors.forename: Jun-Jie
authors.initials: JJ
authors.lastname: Zhang
authors.forename: Hong
authors.initials: H
authors.lastname: Liu
authors.forename: Ning-Yi
authors.initials: NY
authors.lastname: Zhou
mesh_terms: D055162:Biocatalysis; D001673:Biodegradation, Environmental; D001711:Biotransformation; D002396:Catechols / Q000378:metabolism*; D049308:Dioxygenases / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D006873:Hydroquinones / Q000378:metabolism; D010105:Oxygenases / Q000302:isolation & purification / Q000378:metabolism*; D011549:Pseudomonas / Q000201:enzymology* / Q000254:growth & development; D013053:Spectrophotometry; D013997:Time Factors
chemical_list: D002396:Catechols; D006873:Hydroquinones; C013038:hydroxyhydroquinone; D010105:Oxygenases; D049308:Dioxygenases; C041894:hydroxyquinol 1,2-dioxygenase; C113515:4-nitrophenol monooxygenase; C001833:4-nitrocatechol