This pathway was contributed by David Wunder, University of Minnesota BioC 5309 and updated by Michael Turnbull, University of Minnesota.
2,4-Dichlorotoluene (2,4-DCT) is a halogenated aromatic hydrocarbon. In the chemical production industry it is found as an intermediate in the synthesis of agrochemicals (e.g., pesticides, herbicides) and pharmaceuticals. Toxicity data for compounds structurally similar to DCTs indicate that it likely exhibits moderate toxicity to aquatic organisms, and will have a moderate potential for bioaccumulation in the environment. 2,4-DCT is hydrophobic, meaning it may be subject to soil and sediment adsorption. 2,4-DCT is also volatile and has been characterized by the EPA as a hazardous air pollutant (HAP).
The aerobic pathway for biodegradation of 2,4-DCT is initiated by Ralstonia sp. strain PS12 (Pollman et al., 2002). Ring dioxygenation is followed by intradiol cleavage to form 3,5-dichloro-3-methylmuconate. Subsequent degradation involves two different methods for dechlorination. The methylmaleylacetate derivates listed here are the last known intermediates, and are assumed to enter more common intermediary metabolism, but their further metabolism is not well-characterized. Under anaerobic conditions, 2,4-DCT is subject to reductive dehalogenation (loss of chlorine), ultimately entering the anerobic toluene biodegradative pathway.
The following is a text-format 2,4-Dichlorotoluene pathway map. An organism which can initiate the pathway is given, but other organisms may also carry out later steps. Follow the links for more information on compounds or reactions. This map is also available in graphic (14k) format.
2,4-Dichlorotoluene
Ralstonia sp. PS12
|
|
| tetrachlorobenzene
| dioxygenase
|
v
4,6-Dichloro-3-methyl-
cis-1,2-dihydroxycyclohexa-3,5-diene
|
|
| chlorobenzene dihydrodiol
| dehydrogenase
|
v
4,6-Dichloro-3-methylcatechol
|
|
| chlorocatechol
| 1,2-dioxygenase
|
v
3,5-Dichloro-3-methylmuconate
|
|
+----------------------+----------------------+
| |
| chloromuconate | chloromuconate
| cycloisomerase | cycloisomerase
| |
v v
2-Chloro-5-methyl-cis-dienelactone 3,5-Dichloro-2-methylmuconolactone
| |
| |
| dienelactone | chloromuconate
| hydrolase | cycloisomerase
| |
v v
2-Chloro-5-methylmaleylacetate 2-Chloro-3-methyl-cis/trans-dienelactone
| |
| |
| maleylacetate | dienelactone
| reductase | hydrolase
| |
v v
5-Methylmaleylacetate 3-Chloro-2-methylmaleylacetate
|
|
| maleylacetate
| reductase
|
v
2-Methyl-3-oxoadipate
Page Author(s): David Wunder and Michael Turnbull
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