Sequencing of Comamonas testosteroni strain B-356-biphenyl/chlorobiphenyl dioxygenase genes: evolutionary relationships among Gram-negative bacterial biphenyl dioxygenases.

In a previous work, all three components of Comamonas testosteroni B-356 biphenyl (BPH)/chlorobiphenyls (PCBs) dioxygenase (dox) have been purified and characterized. They include an iron-sulphur protein (ISPBPH) which is the terminal oxygenase composed of two subunits (encoded by bphA and bphE), a ferredoxin (FERBPH) encoded by bphF and a reductase (REDBPH) encoded by bphG. bphG Is not located in the neighbourhood of bphAEF in B-356. We are reporting the cloning of B-356-bphG and the sequencing of B-356-BPH dox genes. Comparative analysis of the genes provided genetic evidence showing that two BPH dox lineages have emerged in Gram-negative bacteria. The main features of the lineage that includes B-356 are the location of bphG outside the bph gene cluster and the structure of REDBPH which is very distinct from all other aryl dioxygenase-reductases.