title: Degradation of 2,4,5-trichlorophenol by the lignin-degrading basidiomycete Phanerochaete chrysosporium.
abstract: Under secondary metabolic conditions the white rot basidiomycete Phanerochaete chrysosporium rapidly mineralizes 2,4,5-trichlorophenol. The pathway for degradation of 2,4,5-trichlorophenol was elucidated by the characterization of fungal metabolites and oxidation products generated by purified lignin peroxidase (LiP) and manganese peroxidase (MnP). The multistep pathway involves cycles of peroxidase-catalyzed oxidative dechlorination reactions followed by quinone reduction reactions to yield the key intermediate 1,2,4,5-tetrahydroxybenzene, which is presumably ring cleaved. In the first step of the pathway, 2,4,5-trichlorophenol is oxidized to 2,5-dichloro-1,4-benzoquinone by either MnP or Lip. 2,5-Dichloro-1,4-benzoquinone is then reduced to 2,5-dichloro-1,4-hydroquinone. The 2,5-dichloro-1,4-hydroquinone is oxidized by MnP to generate 5-chloro-4-hydroxy-1,2-benzoquinone. The orthoquinone is in turn reduced to 5-chloro-1,2,4-trihydroxybenzene. Finally, the 5-chlorotrihydroxybenzene undergoes another cycle of oxidative dechlorination and reduction reactions to generate 1,2,4,5-tetrahydroxybenzene. The latter is presumably ring cleaved, with subsequent degradation to CO2. In this pathway, the substrate is oxidatively dechlorinated by LiP or MnP in a reaction which produces a quinone. The quinone intermediate is recycled by a reduction reaction to regenerate an intermediate which is again a substrate for peroxidase-catalyzed oxidative dechlorination. This pathway apparently results in the removal of all three chlorine atoms before ring cleavage occurs.
authors.affiliation: Department of Chemical and Biological Sciences, Oregon Graduate Institute of Science and Technology, Beaverton 97006-1999.
authors.forename: D K
authors.initials: DK
authors.lastname: Joshi
authors.forename: M H
authors.initials: MH
authors.lastname: Gold
mesh_terms: D001487:Basidiomycota / Q000201:enzymology*; D001673:Biodegradation, Environmental; D002733:Chlorophenols / Q000378:metabolism*; D010544:Peroxidases / Q000378:metabolism*
chemical_list: D002733:Chlorophenols; C009534:2,4,5-trichlorophenol; D010544:Peroxidases; C042858:lignin peroxidase; C051129:manganese peroxidase