Molecular Characterization of a Novel
            <i>ortho</i>
            -Nitrophenol Catabolic Gene Cluster in
            <i>Alcaligenes</i>
            sp. Strain NyZ215

Xiao, Yi; Zhang, Jun‐Jie; Liu, Hong; Zhou, Ning‐Yi

doi:10.1128/jb.00654-07

Cited by 47 publications

(40 citation statements)

References 48 publications

(36 reference statements)

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“…OnpB of this pathway is thought to reduce the quinone to a catechol. The onpB gene is required when the pathway genes are transferred to Pseudomonas putida PaW340, indicating OnpB catalyzes a critical step in o-nitrophenol degradation in vivo (23). For pentachlorophenol degradation in Sphingobium chlorophenolicum, pentachlorophenol monooxygenase oxidizes pentachlorophenol to tetrachloro-p-quinone.…”

Section: Discussionmentioning

confidence: 99%

Functions of Flavin Reductase and Quinone Reductase in 2,4,6-Trichlorophenol Degradation by Cupriavidus necator JMP134

Belchik

Xun

2008

J Bacteriol

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The tcpRXABCYD operon of Cupriavidus necator JMP134 is involved in the degradation of 2,4,6-trichlorophenol (2,4,6-TCP), a toxic pollutant. TcpA is a reduced flavin adenine dinucleotide (FADH 2 )-dependent monooxygenase that converts 2,4,6-TCP to 6-chlorohydroxyquinone. It has been implied via genetic analysis that TcpX acts as an FAD reductase to supply TcpA with FADH 2 , whereas the function of TcpB in 2,4,6-TCP degradation is still unclear. In order to provide direct biochemical evidence for the functions of TcpX and TcpB, the two corresponding genes (tcpX and tcpB) were cloned, overexpressed, and purified in Escherichia coli. TcpX was purified as a C-terminal His tag fusion (TcpX H ) and found to possess NADH:flavin oxidoreductase activity capable of reducing either FAD or flavin mononucleotide (FMN) with NADH as the reductant. TcpX H had no activity toward NADPH or riboflavin. Coupling of TcpX H and TcpA demonstrated that TcpX H provided FADH 2 for TcpA catalysis. Among several substrates tested, TcpB showed the best activity for quinone reduction, with FMN or FAD as the cofactor and NADH as the reductant. TcpB could not replace TcpX H in a coupled assay with TcpA for 2,4,6-TCP metabolism, but TcpB could enhance TcpA activity. Further, we showed that TcpB was more effective in reducing 6-chlorohydroxyquinone than chemical reduction alone, using a thiol conjugation assay to probe transitory accumulation of the quinone. Thus, TcpB was acting as a quinone reductase for 6-chlorohydroxyquinone reduction during 2,4,6-TCP degradation.

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Section: Discussionmentioning

confidence: 99%

Functions of Flavin Reductase and Quinone Reductase in 2,4,6-Trichlorophenol Degradation by Cupriavidus necator JMP134

Belchik

Xun

2008

J Bacteriol

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“…Molecular characterization of Alcaligenes sp. strain NyZ215 revealed that the genes encoding the 2-nitrophenol monooxygenase (OnpA), 2-benzoquinone reductase (OnpB), and catechol 1,2-dioxygenase (OnpC) are transcribed as a single operon (210).…”

Section: Pathways For Nitrophenol Catabolismmentioning

confidence: 99%

Nitroaromatic Compounds, from Synthesis to Biodegradation

Parales

2010

Microbiol Mol Biol Rev

714

470

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SUMMARY Nitroaromatic compounds are relatively rare in nature and have been introduced into the environment mainly by human activities. This important class of industrial chemicals is widely used in the synthesis of many diverse products, including dyes, polymers, pesticides, and explosives. Unfortunately, their extensive use has led to environmental contamination of soil and groundwater. The nitro group, which provides chemical and functional diversity in these molecules, also contributes to the recalcitrance of these compounds to biodegradation. The electron-withdrawing nature of the nitro group, in concert with the stability of the benzene ring, makes nitroaromatic compounds resistant to oxidative degradation. Recalcitrance is further compounded by their acute toxicity, mutagenicity, and easy reduction into carcinogenic aromatic amines. Nitroaromatic compounds are hazardous to human health and are registered on the U.S. Environmental Protection Agency's list of priority pollutants for environmental remediation. Although the majority of these compounds are synthetic in nature, microorganisms in contaminated environments have rapidly adapted to their presence by evolving new biodegradation pathways that take advantage of them as sources of carbon, nitrogen, and energy. This review provides an overview of the synthesis of both man-made and biogenic nitroaromatic compounds, the bacteria that have been identified to grow on and completely mineralize nitroaromatic compounds, and the pathways that are present in these strains. The possible evolutionary origins of the newly evolved pathways are also discussed.

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“…OnpB from the ONP-utilizing strain NyZ215, reducing o-benzoquinone to catechol, was demonstrated to be a critical enzyme in ONP degradation in vivo when the pathway genes were transferred to P. putida PaW340 (37). Similarly, TcpB, acting as a quinone reductase for 6-chlorohydroxyquinone reduction, was also confirmed to play a critical role in 2,4,6-TCP degradation in strain JMP134, although tcpB inactivation mutants still oxidize 2,4,6-TCP (3).…”

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confidence: 99%

Identification and Characterization of Catabolicpara-Nitrophenol 4-Monooxygenase andpara-Benzoquinone Reductase fromPseudomonassp. Strain WBC-3

et al. 2009

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Pseudomonas sp. strain WBC-3 utilizes para-nitrophenol (PNP) as a sole source of carbon, nitrogen, and energy. In order to identify the genes involved in this utilization, we cloned and sequenced a 12.7-kb fragment containing a conserved region of NAD(P)H:quinone oxidoreductase genes. Of the products of the 13 open reading frames deduced from this fragment, PnpA shares 24% identity to the large component of a 3-hydroxyphenylacetate hydroxylase from Pseudomonas putida U and PnpB is 58% identical to an NAD(P)H:quinone oxidoreductase from Escherichia coli. Both PnpA and PnpB were purified to homogeneity as His-tagged proteins, and they were considered to be a monomer and a dimer, respectively, as determined by gel filtration. PnpA is a flavin adenine dinucleotide-dependent single-component PNP 4-monooxygenase that converts PNP to para-benzoquinone in the presence of NADPH. PnpB is a flavin mononucleotide-and NADPH-dependent p-benzoquinone reductase that catalyzes the reduction of p-benzoquinone to hydroquinone. PnpB could enhance PnpA activity, and genetic analyses indicated that both pnpA and pnpB play essential roles in PNP mineralization in strain WBC-3. Furthermore, the pnpCDEF gene cluster next to pnpAB shares significant similarities with and has the same organization as a gene cluster responsible for hydroquinone degradation (hapCDEF) in Pseudomonas fluorescens ACB (M. J. Moonen, N.

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Molecular Characterization of a Novel ortho -Nitrophenol Catabolic Gene Cluster in Alcaligenes sp. Strain NyZ215

Cited by 47 publications

References 48 publications

Functions of Flavin Reductase and Quinone Reductase in 2,4,6-Trichlorophenol Degradation by Cupriavidus necator JMP134

Functions of Flavin Reductase and Quinone Reductase in 2,4,6-Trichlorophenol Degradation by Cupriavidus necator JMP134

Nitroaromatic Compounds, from Synthesis to Biodegradation

Identification and Characterization of Catabolicpara-Nitrophenol 4-Monooxygenase andpara-Benzoquinone Reductase fromPseudomonassp. Strain WBC-3

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