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 pollutant, The initial steps of PCP degradation by Sphingomonas chlorophenolica ATCC 39723 have been studied and characterized, Two enzymes are responsible for converting PCP to 2,6-dichloro-p-hydroquinone (2,6-DiCH) which is a common metabolic intermediate of the biodegradation of polychlorinated phenols, 2,6-DiCH is degraded by PcpA from strain ATCC 39723, but the reaction end product has been misidentified as 6-chlorohydroxyquinol and has been elusive to detection, We report here the overproduction of PcpA in Escherichia coli and the demonstration of quantitative conversion of 2,6-DiCH to 2-chloromaleylacetate with the coconsumption of one equivalent O-2 and release of one equivalent Cl- by purified PcpA. On the basis of the reaction stoichiometry, the enzyme is proposed to be 2,6-DiCH 1,2-dioxygenase. (C) 1999 Academic Press.