This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
|Superclasses:||Degradation/Utilization/Assimilation → Aromatic Compounds Degradation|
Expected Taxonomic Range: Proteobacteria
Organophosphate pesticides such as parathion and methyl parathionhave been used extensively as insecticides, fungicides, and herbicides. Methyl parathion is used primarily to kill insects on farm crops, especially cotton. It can no longer be used on food crops commonly consumed by children. Methyl parathion is a cholinesterase inhibitor, and exposure to very high levels for a short period in air or water may cause death. Changes in mental state may last several months after exposure has ended. EPA regulations allow 0.002 mg/L of methyl parathion in drinking water.
About This Pathway
A few organisms can degrade methyl-parathion and completely mineralize it. A Pseudomonas putida strain has been documented to degrade both both methyl parathion as a sole carbon and phosphorus source [Rani94]. This organism hydrolyzed methyl-parathion to 4-nitrophenol, which was subsequently degraded via hydroquinone and 1,2,4-benzenetriol to maleyl-acetate. A Pseudomonas strain designated Pseudomonas sp. A3 can use methyl-parathion as a sole carbon, energy, and phosphorus source [Ramanathan99]. The 4-nitrophenol provided carbon and energy, while the other cleavage product, dimethylthiophosphate, was used as a phosphorus source.
Pseudomonas sp. WBC-3 can utilize methyl-parathion as a sole carbon, energy, and nitrogen source [Liu05]. The genes encoding the required enzymes are carried on a 70 kb plasmid designated pZWL0. The mpd gene encoding the methyl-parathion hydrolyzing enzyme has been cloned from this organism and succssfully expressed in Escherichia coli. Interestingly, this gene is completely different from the opd genes encoding parathion hydrolases.
The key enzyme in methyl-parathion degradation is methyl-parathion hydrolase, which has been described in a variety of bacteria.
Unlike the organisms mentioned above, an organism identified as Plesiomonas sp. M6 is able to hydrolyze methyl-parathion to p-nitrophenol, but is not able to degrade p-nitrophenol further. The gene encoding the methyl-parathion hydrolyzing enzyme in this organism has been cloned and succssfully expressed in Escherichia coli [Vecchioni75]. It is almost identical to the plasmid-borne mpd gene cloned from Pseudomonas sp. WBC-3, but is located on the chromosome.
According to at least one publication, dimethylthiophosphate is degraded to methane, phosphate and sulfate, enabling the organism to utilze methyl parathion as the sole phosphorus source [Ramanathan99]. The exact path for this degradation is not known.
Liu05: Liu H, Zhang JJ, Wang SJ, Zhang XE, Zhou NY (2005). "Plasmid-borne catabolism of methyl parathion and p-nitrophenol in Pseudomonas sp. strain WBC-3." Biochem Biophys Res Commun 334(4);1107-14. PMID: 16039612
Bondarenko04: Bondarenko S, Gan J, Haver DL, Kabashima JN (2004). "Persistence of selected organophosphate and carbamate insecticides in waters from a coastal watershed." Environ Toxicol Chem 23(11);2649-54. PMID: 15559280
Kitagawa04: Kitagawa W, Kimura N, Kamagata Y (2004). "A novel p-nitrophenol degradation gene cluster from a gram-positive bacterium, Rhodococcus opacus SAO101." J Bacteriol 186(15);4894-902. PMID: 15262926
Perry07: Perry LL, Zylstra GJ (2007). "Cloning of a gene cluster involved in the catabolism of p-nitrophenol by Arthrobacter sp. strain JS443 and characterization of the p-nitrophenol monooxygenase." J Bacteriol 189(21);7563-72. PMID: 17720792
Zhang09b: Zhang JJ, Liu H, Xiao Y, Zhang XE, Zhou NY (2009). "Identification and characterization of catabolic para-nitrophenol 4-monooxygenase and para-benzoquinone reductase from Pseudomonas sp. strain WBC-3." J Bacteriol 191(8);2703-10. PMID: 19218392
Zhang12a: Zhang S, Sun W, Xu L, Zheng X, Chu X, Tian J, Wu N, Fan Y (2012). "Identification of the para-nitrophenol catabolic pathway, and characterization of three enzymes involved in the hydroquinone pathway, in pseudomonas sp. 1-7." BMC Microbiol 12;27. PMID: 22380602
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