Identification of a eukaryotic reductive dechlorinase and characterization of its mechanism of action on its natural substrate.
Chlorinated compounds are important environmental pollutants whose biodegradation may be limited by inefficient dechlorinating enzymes. Dictyostelium amoebae produce a chlorinated alkyl phenone called DIF which induces stalk cell differentiation during their multicellular development. Here we describe the identification of DIF dechlorinase. DIF dechlorinase is active when expressed in bacteria, and activity is lost from Dictyostelium cells when its gene, drcA, is knocked out. It has a K(m) for DIF of 88 nM and K(cat) of 6.7 s(-1). DrcA is related to glutathione S-transferases, but with a key asparagine-to-cysteine substitution in the catalytic pocket. When this change is reversed, the enzyme reverts to a glutathione S-transferase, thus suggesting a catalytic mechanism. DrcA offers new possibilities for the rational design of bioremediation strategies.
Laboratory of Molecular Biology, Medical Research Council, Cambridge CB2 0QH, UK. fv@mrc-lmb.cam.ac.uk
Francisco
F
Velazquez
Sew Yu
SY
Peak-Chew
Israel S
IS
Fernández
Christopher S
CS
Neumann
Robert R
RR
Kay
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001216:Asparagine; D001483:Base Sequence; D020134:Catalytic Domain; D017124:Conserved Sequence; D003545:Cysteine; D004023:Dictyostelium / Q000201:enzymology*; D055786:Gene Knockout Techniques; D005978:Glutathione / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D006586:Hexanes / Q000378:metabolism; D006588:Hexanones / Q000378:metabolism*; D006843:Hydrocarbons, Chlorinated / Q000378:metabolism*; D007700:Kinetics; D008190:Lyases / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010088:Oxidoreductases; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity
C075859:DIF-1 3(5)-dechlorinase; C490570:Differentiation-inducing factor-1, Dictyostelium; D006586:Hexanes; D006588:Hexanones; D006843:Hydrocarbons, Chlorinated; D015800:Protozoan Proteins; D001216:Asparagine; D010088:Oxidoreductases; D005982:Glutathione Transferase; D008190:Lyases; D005978:Glutathione; D003545:Cysteine