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 ability of the enzyme biphenyl 2,3-dioxygenase (BPDO) to catalyze their oxygenation. Analysis of hybrid BPDOs obtained using common restriction sites to exchange large DNA fragments between LB400 bphA and B-356 bphA showed that the C-terminal portion of LB400 alpha subunit can withstand extensive structural modifications, and that these modifications can change the catalytic properties of the enzyme. On the other hand, exchanging the C-terminal portion of B-356 BPDO alpha subunit with that of LB400 alpha subunit generated inactive chimeras. Data encourage an enzyme engineering approach, consisting of introducing extensive modifications of the C-terminal portion of LB400 bphA to extend BPDO catalytic properties toward polychlorinated biphenyls.