Expression of a mammalian cytochrome P-450 in Nicotiana tabacum for bioremediation of PCB contaminated soils

Abstract

Polychlorinated biphenyls (PCBs) are resistant to metabolism in most animal species. The dog has the unique ability to metabolize and eliminate certain PCB congeners, as a result of the activity of the cytochrome P450 isozyme PBD-2. An expressible cDNA coding for PBD-2 has been introduced into the genome of tobacco plants. The PBD-2 cDNA coding sequence and a screenable marker gene coding for neomycin phosphotransferase II were introduced into tobacco leaf disks using a binary Agrobacterium tumefaciens vector system. Southern and Western blot analysis have confirmed chromosomal integration of the cDNA and expression of the PBD-2 polypeptide. Differential centrifugation and Western blot analyses have shown the PBD-2 protein to be associated with a membrane fraction in transgenic tobacco leaf homogenates. Measurements of marker enzymes from linear sucrose gradient fractions and Western blotting show the PBD-2 protein to be associated with the endoplasmic reticulum. Our goal is to develop transgenic plants in which the PBD-2 protein metabolizes PCBs, thus providing a novel method for bioremediation of PCB-contaminated soils.