Phylogenetic tree of oxygenases homologous to LigX, drawn using GENETIX version 10.1 software. The numbers on some of the branches refer to the confidence estimated by bootstrap analysis (100 replications). Class I type oxygenases consist of two proteins, an oxygenase and an oxidoreductase, that act as a ferredoxin and a ferredoxin reductase. Class II type oxygenases consist of three proteins: an oxygenase, a ferredoxin, and a ferredoxin reductase. BnzA_PSEPU, benzene 1,2-dioxygenase α subunit of Pseudomonas putida (accession no. P08084) (14); BphA_PSEPS, biphenyl dioxygenase α subunit of P. pseudoalcaligenes KF707 (Q52028) (38); CbaA_ALCSP, 3-chlorobenzoate 3,4-dioxygenase of Alcaligenes sp. strain BR60 (Q44256) (27); NdoB_PSEPU, naphthalene 1,2-dioxygenase α subunit of P. putida NCIB9816 (P23094) (19); PobA_PSEPS, phenoxybenzoate dioxygenase α subunit of P. pseudoalcaligenes POB310 (Q52185) (10); Pht3_PSEPU, phthalate 4,5-dioxygenase oxygenase subunit of P. putida (Q05183) (32); Tod1_PSEPU, toluene 2,3-dioxygenase α subunit of P. putida F1 (P13450) (42); VanA_PSES9, vanillate O-demethylase oxygenase subunit of Pseudomonas sp. strain ATCC 19151 (P12609) (7); VanA_PSESP, vanillate O-demethylase oxygenase subunit of Pseudomonas sp. strain HR199 (O05616) (36).