Characterization of hybrid biphenyl dioxygenases obtained by recombining Burkholderia sp strain LB400 bphA with the homologous gene of Comamonas testosteroni B-356

The bacterial degradation of polychlorinated biphenyls depends on the abili ty of the enzyme biphenyl 2,3-dioxygenase (BPDO) to catalyze their oxygenat ion. Analysis of hybrid BPDOs obtained using common restriction sites to ex change large DNA fragments between LB400 bphA and B-356 bphA showed that th e C-terminal portion of LB400 alpha subunit can withstand extensive structu ral modifications, and that these modifications can change the catalytic pr operties of the enzyme. On the other hand, exchanging the C-terminal portio n of B-356 BPDO alpha subunit with that of LB400 alpha subunit generated in active chimeras. Data encourage an enzyme engineering approach, consisting of introducing extensive modifications of the C-terminal portion of LB400 b phA to extend BPDO catalytic properties toward polychlorinated biphenyls.