title: A two-component tetrachlorohydroquinone reductive dehalogenase system from the lignin-degrading basidiomycete Phanerochaete chrysosporium.
abstract: Tetrachloro-1,4-hydroquinone (TClHQ) is an intermediate in the degradation of pentachlorophenol by the lignin-degrading basidiomycete Phanerochaete chrysosporium. Two enzymes required for the reductive dehalogenation of TClHQ to trichlorohydroquinone (TrClHQ) were identified in cell-free extracts of P. chrysosporium. In the presence of GSH, a membrane-bound enzyme converted TClHQ to the glutathionyl conjugate of TrClHQ (GS-TrClHQ). This membrane-bound glutathione transferase was specific for GSH as a cosubstrate. In the second step of the reductive dehalogenation reaction, a soluble enzyme fraction converted GS-TrClHQ to TrClHQ in the presence of GSH, cysteine, or dithiothreitol. Thus, this second enzyme appears to be a GS-conjugate reductase. These two enzyme fractions, working in tandem, also reductively dehalogenated TrClHQ and 2,6-dichlorohydroquinone, which are intermediates in the degradation of chlorophenols by this organism.
authors: Department of Biochemistry and Molecular Biology, Oregon Graduate Institute of Science and Technology, Portland, Oregon, 97291-1000, USA.
authors: G V
authors: GV
authors: Reddy
authors: M H
authors: MH
authors: Gold
mesh_terms: D002458:Cell Fractionation; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism; D002713:Chlorine / Q000378:metabolism; D002733:Chlorophenols / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003545:Cysteine / Q000378:metabolism; D003600:Cytosol / Q000201:enzymology / Q000378:metabolism; D004229:Dithiothreitol / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D005982:Glutathione Transferase / Q000302:isolation & purification / Q000378:metabolism; D006219:Halogens / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D006873:Hydroquinones / Q000737:chemistry / Q000378:metabolism*; D008031:Lignin / Q000378:metabolism; D013058:Mass Spectrometry; D010088:Oxidoreductases / Q000302:isolation & purification / Q000378:metabolism; D020075:Phanerochaete / Q000201:enzymology* / Q000378:metabolism; D019163:Reducing Agents / Q000378:metabolism; D012995:Solubility; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D002733:Chlorophenols; D006219:Halogens; D006873:Hydroquinones; D019163:Reducing Agents; C104629:2,6-dichloro-4-hydroquinone; D002713:Chlorine; C044578:2,3,5,6-tetrachlorohydroquinone; D008031:Lignin; D010088:Oxidoreductases; D005982:Glutathione Transferase; D005978:Glutathione; D003545:Cysteine; D004229:Dithiothreitol