Characterization of 2,6-dichloro-p-hydroquinone 1,2-dioxygenase (PcpA) of Sphingomonas chlorophenolica ATCC 39723

Pentachlorophenol (PCP) is a general biocide and a major environmental poll utant, The initial steps of PCP degradation by Sphingomonas chlorophenolica ATCC 39723 have been studied and characterized, Two enzymes are responsibl e for converting PCP to 2,6-dichloro-p-hydroquinone (2,6-DiCH) which is a c ommon metabolic intermediate of the biodegradation of polychlorinated pheno ls, 2,6-DiCH is degraded by PcpA from strain ATCC 39723, but the reaction e nd product has been misidentified as 6-chlorohydroxyquinol and has been elu sive to detection, We report here the overproduction of PcpA in Escherichia coli and the demonstration of quantitative conversion of 2,6-DiCH to 2-chl oromaleylacetate with the coconsumption of one equivalent O-2 and release o f one equivalent Cl- by purified PcpA. On the basis of the reaction stoichi ometry, the enzyme is proposed to be 2,6-DiCH 1,2-dioxygenase. (C) 1999 Aca demic Press.