Biodegradation of dioxins by recombinant Escherichia coli expressing rat CYP1A1 or its mutant

Among polychlorinated dibenzo-p-dioxins (PCDDs), 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TetraCDD) is the most toxic one. Recently, we reported that rat CYP1A1 mutant, F240A, expressed in yeast showed metabolic activity toward 2,3,7,8-TetraCDD. In this study, we successfully expressed N-terminal truncated P450s (Delta1A1 and DeltaF240A) in Escherichia coli cells. Kinetic analysis using membrane fractions prepared from the recombinant E. coli cells revealed that DeltaF240A has enzymatic properties similar to F240A expressed in yeast. The metabolism of PCDDs by recombinant E. coli cells expressing both DeltaF240A and human NADPH-P450 reductase was also examined. When 2,3,7-TriCDD was added to the E. coli cell culture at a final concentration of 10 microM, approximately 90% of the 2,3,7-TriCDD was converted into multiple metabolites within 8 h. These results indicate the possible application of prokaryotic cells expressing DeltaF240A to the bioremediation of PCDD-contaminated soil.