Oxygenases and dehalogenases: Molecular approaches to efficient degradation of chlorinated environmental pollutants

Microbial oxygenases and dehalogenases are key enzymes in the degradation of highly chlorinated compounds, which often become significant environmental pollutants. Oxygenases engineered by the methods of directed evolution exhibit enhanced degradation of PCBs and other chlorinated solvents such as trichloroethene and pentachloroethane. Dehalorespiration is an efficient dechlorination mechanism that is coupled with energy-yielding phosphorylation. Recently, a variety of chloroethene-dehalorespiring anaerobes have been isolated, and their reductive dehalogmases have been characterized in biochemical and genetic bases. This review. describes our recent studies on dioxygenases and reductive dehalogenases.