title: The evolutionary relationship of biphenyl dioxygenase from gram-positive Rhodococcus globerulus P6 to multicomponent dioxygenases from gram-negative bacteria.
abstract: The Gram+ bacterium Rhodococcus globerulus P6 (RgP6) catabolizes a range of polychlorinated biphenyl (PCB) congeners, thus being of interest in bioelimination processes for PCB. The first step in the pathway, a dioxygenase attack of one of the biphenyl (BP) rings, is catalyzed by biphenyl dioxygenase (BDO). In this study, the nucleotide (nt) sequences of the four clustered cistrons, bphA1A2A3A4, encoding the subunits of BDO and forming part of the bph operon of RgP6 for BP degradation, were determined. A conserved motif proposed to bind a Rieske-type [2Fe-2S] cluster was identified in the deduced amino acid (aa) sequence of both the a subunit of the terminal oxygenase (BphA1) and ferredoxin (BphA3). The ferredoxin reductase subunit (BphA4) contains conserved sites for FAD and NADH binding. Deduced aa sequences of the BDO subunits shared homologies to multicomponent aromatic ring-hydroxylating dioxygenases from Gram- microorganisms. Stronger identity was found to toluene dioxygenase (TDO) of Pseudomonas putida F1 than to other BDO. Aa sequence comparisons suggest that BP degradation genes of RgP6 may have originated in Gram- microorganisms, probably Pseudomonas, and subsequently transferred to this Gram+ bacterium.
authors.affiliation: Department of Microbiology, GBF-National Research Centre for Biotechnology, Braunschweig, Germany.
authors.forename: J A
authors.initials: JA
authors.lastname: Asturias
authors.forename: E
authors.initials: E
authors.lastname: Díaz
authors.forename: K N
authors.initials: KN
authors.lastname: Timmis
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D005288:Ferredoxins / Q000235:genetics; D005798:Genes, Bacterial / Q000235:genetics*; D007506:Iron-Sulfur Proteins; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics*; D009876:Operon / Q000235:genetics; D010088:Oxidoreductases / Q000235:genetics; D010105:Oxygenases / Q000737:chemistry / Q000235:genetics*; D010802:Phylogeny; D011078:Polychlorinated Biphenyls / Q000378:metabolism; D016958:Pseudomonas putida / Q000201:enzymology* / Q000235:genetics; D015183:Restriction Mapping; D012240:Rhodococcus / Q000201:enzymology* / Q000235:genetics; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
chemical_list: D005288:Ferredoxins; D007506:Iron-Sulfur Proteins; D011078:Polychlorinated Biphenyls; D010088:Oxidoreductases; D010105:Oxygenases; C023172:toluene dioxygenase; C074161:biphenyl-2,3-dioxygenase