Involvement of mixed function oxidase systems in polychlorinated biphenyl metabolism by plant cells

Lee, In-Cheol; Fletcher, John S.

doi:10.1007/bf00235262

Cited by 35 publications

(22 citation statements)

References 9 publications

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“…The second and third types were set up by addition of 1 mL of 1 mM n-propylgallate or 1 mL of 1 mM 1-aminobenzotriazole solution as enzyme inhibitors. n-propylgallate is known to be a plant peroxidase inhibitor and 1-aminobenzotriazole is a plant P-450 inhibitor (Lee & Fletcher 1992;Mackova et al 2001). The controls were subjected to the same procedures as the experimental replicates.…”

Section: Methodsmentioning

confidence: 98%

“…any differences among 2,2¢-PCB, 2,4¢-PCB and 4,4¢-PCB) cannot be determined. Previous reports have pointed out that the position of the chloride substitutes does affect the metabolic rates of PCBs (Lee & Fletcher 1992). In Lee & Fletcher's (1992) study, almost all the congeners subject to metabolism had a single substitution in the 2-position of the molecule, and it was concluded that variations in the conformation of different PCBs may explain their metabolism within plant cells.…”

Section: Degradation Of Pcbsmentioning

confidence: 96%

“…The involvement of plant cell oxidative systems in metabolism of PCBs has been suggested Lee & Fletcher (1992) who reported the degradation of 19 PCB congeners ranging from 2 to 6 chlorine substitutes in Rosa spp. cell culture.…”

Section: Introductionmentioning

confidence: 97%

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Accumulation, distribution and transformation of DDT and PCBs by Phragmites australis and Oryza sativa L.: II. Enzyme study

Chu

Wong

Zhang

2006

Environ Geochem Health

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Two wetland plant species, Phragmites australis and Oryza sativa, were grown in a glasshouse under hydroponics conditions. Enzyme extracts from different parts of the plants were used to determine the transformation rate of o,p'-DDT, p,p'-DDT and PCBs. The organic pollutants were directly spiked into the enzyme extracts, and samples were collected every 30 min and analyzed with a GC-ECD. Root extracts of P. australis readily degraded and transformed DDT and some PCB congeners with a low degree of chlorination. In contrast, crude extracts of O. sativa showed no appreciable degradation or transformation of DDT or PCBs. Inhibition studies indicated that the degradation and transformation of both DDT and PCBs by P. australis enzymes were partly mediated by peroxidase and the plant P-450 system. PCBs with a high degree of chlorination were highly resistant to transformation or degradation by plant enzymes. Both wetland plant species accumulated substantial quantities of the persistent organic chemicals but had different degradation capacities. The enzyme systems in P. australis were much more effective that those in rice in the degradation and transformation of the organic pollutants.

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Section: Methodsmentioning

confidence: 98%

Section: Degradation Of Pcbsmentioning

confidence: 96%

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Accumulation, distribution and transformation of DDT and PCBs by Phragmites australis and Oryza sativa L.: II. Enzyme study

Chu

Wong

Zhang

2006

Environ Geochem Health

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“…For example, they are produced from microbial metabolism of dibenzofuran, fluorene, and carbazole (26). Furthermore, many reports have now shown that plants metabolize major environmental contaminants such as PCBs to generate hydroxylated derivatives (9,10,21,22,23,28).…”

mentioning

confidence: 99%

Metabolism of 2,2′- and 3,3′-Dihydroxybiphenyl by the Biphenyl Catabolic Pathway of Comamonas testosteroni B-356

Sondossi

Barriault

Sylvestre

2004

Appl Environ Microbiol

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The purpose of this investigation was to examine the capacity of the biphenyl catabolic enzymes of Comamonas testosteroni B-356 to metabolize dihydroxybiphenyls symmetrically substituted on both rings. Data show that 3,3-dihydroxybiphenyl is by far the preferred substrate for strain B-356. However, the dihydrodiol metabolite is very unstable and readily tautomerizes to a dead-end metabolite or is dehydroxylated by elimination of water. The tautomerization route is the most prominent. Thus, a very small fraction of the substrate is converted to other hydroxylated and acidic metabolites. Although 2,2-dihydroxybiphenyl is a poor substrate for strain B-356 biphenyl dioxygenase, metabolites were produced by the biphenyl catabolic enzymes, leading to production of 2-hydroxybenzoic acid. Data show that the major route of metabolism involves, as a first step, a direct dehydroxylation of one of the ortho-substituted carbons to yield 2,3,2-trihydroxybiphenyl. However, other metabolites resulting from hydroxylation of carbons 5 and 6 of 2,2-dihydroxybiphenyl were also produced, leading to dead-end metabolites.The enzymes of the bacterial biphenyl catabolic pathway are very versatile. They can cometabolically transform several biphenyl analogs, including polychlorinated biphenyls (PCBs) (1, 31), hydroxybiphenyls, and chlorohydroxybiphenyls (33). The four enzymatic steps required to transform biphenyl or its analogs into corresponding benzoic acids are illustrated in Fig. 1. The initial reaction of this pathway is catalyzed by the biphenyl dioxygenase (BPDO) (13, 16). The cis-(2R,3S)-dihydroxy-1-phenylcyclohexa-4,6-diene(cis-biphenyl-2,3-dihydrodiol) (commonly called cis-2,3-dihydro-2,3-dihydroxybiphenyl) generated by the catalytic oxygenation of biphenyl is dehydrogenated by the 2,3-dihydro-2,3-dihydroxybiphenyl 2,3-dehydrogenase (BphB), and the catechol produced is cleaved by the 2,3-dihydroxybiphenyl 1,2-dioxygenase. The 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid (HOPDA) is then hydrolyzed by the HOPDA hydrolase to yield benzoate and hydroxypentanoate. The substrate specificity of BPDO is crucial, because it limits the range of compounds potentially degradable by the catabolic system (14).For example, the three symmetrical ortho, meta, or parasubstituted dichlorinated biphenyl isomers are not metabolized equally well by various BPDOs. Comamonas testosteroni strain B-356 BPDO oxygenates 3,3Ј-dichlorobiphenyl much faster and more efficiently than 2,2Ј-dichlorobiphenyl and 4,4Ј-dichlorobiphenyl. On the other hand, the catalytic activity of Burkholderia sp. strain LB400 BPDO toward 2,2Ј-dichlorobiphenyl is much more efficient than that of B-356 BPDO (17), but 3,3Ј-dichlorobiphenyl and 4,4Ј-dichlorobiphenyl are poor substrates for LB400 BPDO. Nevertheless, metabolites generated from B-356 and LB400 demonstrating BPDO attack on each of these three substrates have been detected and identified (2, 14, 17). It is noteworthy that, for both strains, BPDO attacks 2,2Ј-dichlorobiphenyl principally at position 2,3, which results in...

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“…Selective application of these agents, such as inhibitors and inducers of cytochrome P450, monooxygenases, and peroxidases (Canivenc et al, 1989;Chroma et al, 2002;Cole and Owen, 1987c;Lee and Fletcher, 1992), aids the identification of metabolic relationships and the sites of oxidative enzyme attack, and can be used to modify degradation pathways. This advantage is shared by hydroponic systems, as chemical effectors can also be added readily to hydroponic media.…”

Section: Metabolic Studiesmentioning

confidence: 99%

Application of plant tissue cultures in phytoremediation research: Incentives and limitations

Doran

2009

Biotech & Bioengineering

151

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The aim of this review is to critically assess the benefits and limitations associated with the use of in vitro plant cell and organ cultures as research tools in phytoremediation studies. Plant tissue cultures such as callus, cell suspensions, and hairy roots are applied frequently in phytoremediation research as model plant systems. In vitro cultures offer a range of experimental advantages in studies aimed at examining the intrinsic metabolic capabilities of plant cells and their capacity for toxicity tolerance. The ability to identify the contributions of plant cells to pollutant uptake and detoxification without interference from microorganisms is of particular significance in the search for fundamental knowledge about plants. However, if the ultimate goal of plant tissue culture experiments is the development of practical phytoremediation technology, the limitations inherent in the use of in vitro cultures as a representative of whole plants in the field must be recognized. The bioavailability of contaminants and the processes of pollutant uptake and metabolite distribution are likely to be substantially different in the two systems; this can lead to qualitative as well as quantitative differences in metabolic profiles and tolerance characteristics. Yet, many studies have demonstrated that plant tissue cultures are an extremely valuable tool in phytoremediation research. The results derived from tissue cultures can be used to predict the responses of plants to environmental contaminants, and to improve the design and thus reduce the cost of subsequent conventional whole plant experiments.

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Involvement of mixed function oxidase systems in polychlorinated biphenyl metabolism by plant cells

Cited by 35 publications

References 9 publications

Accumulation, distribution and transformation of DDT and PCBs by Phragmites australis and Oryza sativa L.: II. Enzyme study

Accumulation, distribution and transformation of DDT and PCBs by Phragmites australis and Oryza sativa L.: II. Enzyme study

Metabolism of 2,2′- and 3,3′-Dihydroxybiphenyl by the Biphenyl Catabolic Pathway of Comamonas testosteroni B-356

Application of plant tissue cultures in phytoremediation research: Incentives and limitations

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