A two-component tetrachlorohydroquinone reductive dehalogenase system fromthe lignin-degrading basidiomycete Phanerochaete chrysosporium

Tetrachloro-1,4-hydroquinone (TC1HQ) is an intermediate in the degradation of pentachlorophenol by the lignin-degrading basidiomycete Phanerochaete ch rysosporium, 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 converte d 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 fra ction converted GS-TrClHQ to TrClHQ in the presence of GSH, cysteine, or di thiothreitol. Thus, this second enzyme appears to be a GS-conjugate reducta se, These two enzyme fractions, working in tandem, also reductively dehalog enated TrClHQ and 2,6-dichlorohydroquinone, which are intermediates in the degradation of chlorophenols by this organism. (C) 1999 Academic Press.