Evolution of a metabolic pathway for degradation of a toxic xenobiotic: the patchwork approach.
The pathway for degradation of the xenobiotic pesticide pentachlorophenol in Sphingomonas chlorophenolica probably evolved in the past few decades by the recruitment of enzymes from two other catabolic pathways. The first and third enzymes in the pathway, pentachlorophenol hydroxylase and 2,6-dichlorohydroquinone dioxygenase, may have originated from enzymes in a pathway for degradation of a naturally occurring chlorinated phenol. The second enzyme, a reductive dehalogenase, may have evolved from a maleylacetoacetate isomerase normally involved in degradation of tyrosine. This apparently recently assembled pathway does not function very well: pentachlorophenol hydroxylase is quite slow, and tetrachlorohydroquinone dehalogenase is subject to severe substrate inhibition.
Copley
S D
SD
Dept of Chemistry and Biochemistry and Cooperative Institute for Research in Environmental Studies, University of Colorado at Boulder, Boulder, CO 80309, USA. copley@cires.colorado.edu
D000595:Amino Acid Sequence; D049308:Dioxygenases; D006899:Mixed Function Oxygenases / Q000378:metabolism; D008956:Models, Chemical; D008969:Molecular Sequence Data; D010105:Oxygenases / Q000378:metabolism; D010416:Pentachlorophenol / Q000378:metabolism*; D010575:Pesticides / Q000378:metabolism*; D019800:Phenol / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014443:Tyrosine / Q000378:metabolism
D010575:Pesticides; D019800:Phenol; D014443:Tyrosine; D010416:Pentachlorophenol; D006899:Mixed Function Oxygenases; C119974:2,6-dichlorohydroquinone dioxygenase; D010105:Oxygenases; D049308:Dioxygenases; C069781:pentachlorophenol monooxygenase