title: Metabolism of dibenzofuran and dibenzo-p-dioxin by the biphenyl dioxygenase of Burkholderia xenovorans LB400 and Comamonas testosteroni B-356.
abstract: We examined the metabolism of dibenzofuran (DF) and dibenzo-p-dioxin (DD) by the biphenyl dioxygenase (BPDO) of Comamonas testosteroni B-356 and compared it with that of Burkholderia xenovorans LB400. Data showed that both enzymes oxygenated DF at a low rate, but Escherichia coli cells expressing LB400 BPDO degraded DF at higher rate (30 nmol in 18 h) compared with cells expressing B-356 BPDO (2 nmol in 18 h). Furthermore, both BPDOs produced dihydro-dihydroxy-dibenzofuran as a major metabolite, which resulted from the lateral oxygenation of DF. 2,2',3-Trihydroxybiphenyl (resulting from angular oxygenation of DF) was a minor metabolite produced by both enzymes. Deuterated DF was used to demonstrate the production of 2,2',3-dihydroxybiphenyl through angular oxygenation of DF. When tested for their ability to oxygenate DD, both enzymes produced as sole metabolite, 2,2',3-trihydroxybiphenyl ether at about the same rate, indicating similar catalytic properties toward this substrate. Altogether, although LB400 and B-356 BPDOs oxygenate a different range of chlorobiphenyls, their metabolite profiles toward DF and DD are similar. This suggests that co-planarity influences the regiospecificity of BPDO toward DF and DD to a higher extent than the presence of an ortho substituent on the molecule.
authors.affiliation: Institut National de la Recherche Scientifique, INRS-Institut Armand-Frappier, Québec, Canada.
authors.forename: José-Bruno
authors.initials: JB
authors.lastname: L'Abbée
authors.forename: Diane
authors.initials: D
authors.lastname: Barriault
authors.forename: Michel
authors.initials: M
authors.lastname: Sylvestre
mesh_terms: D001572:Benzofurans / Q000378:metabolism*; D001673:Biodegradation, Environmental; D001713:Biphenyl Compounds / Q000378:metabolism; D019117:Burkholderia / Q000201:enzymology* / Q000235:genetics; D020604:Comamonas testosteroni / Q000201:enzymology* / Q000235:genetics; D004147:Dioxins / Q000378:metabolism*; D049308:Dioxygenases / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D011078:Polychlorinated Biphenyls
chemical_list: D001572:Benzofurans; D001713:Biphenyl Compounds; D004147:Dioxins; C023614:dibenzofuran; D011078:Polychlorinated Biphenyls; D049308:Dioxygenases; C020887:dibenzo(1,4)dioxin