title: Biodegradation of polychlorinated dibenzo-p-dioxins by recombinant yeast expressing rat CYP1A subfamily.
abstract: Metabolism of polychlorinated dibenzo-p-dioxins (PCDDs) by recombinant yeast cells expressing either rat CYP1A1 or CYP1A2 was examined. When each of the dibenzo-p-dioxins (DDs), mono-, di-, and tri-chloroDDs, was added to the cell culture of the recombinant yeast, a remarkable metabolism was observed. The metabolism contained multiple reactions such as hydroxylation at an unsubstituted position, hydroxylation with migration of a chloride substituent, hydroxylation with elimination of a chloride substituent, and opening of dioxin ring. The distinct difference was observed in substrate specificity and reaction specificity between CYP1A1 and CYP1A2. Kinetic analysis using microsomal fractions prepared from the recombinant yeast cells revealed that 2,7-dichloroDD and 2,3,7-trichloroDD were good substrates for both CYP1A1 and CYP1A2. When 2,3,7-trichloroDD was added to the yeast cells expressing each of rat CYP1A1 and CYP1A2, most of 2,3,7-trichloroDD was first converted to 8-hydroxy-2,3,7-trichloroDD, and further metabolized to more hydrophilic compounds whose ethereal bridges were cleaved. These findings give essential information on the metabolism of PCDDs in mammalian liver. In addition, this study indicates the possibility of application of microorganisms expressing mammalian cytochrome P450 to bioremediation of contaminated soils with dioxins.
authors.affiliation: Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kitashirakawa, Oiwake-cho, Sakyo-ku, 606-8502, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Sakaki
authors.forename: Raku
authors.initials: R
authors.lastname: Shinkyo
authors.forename: Teisuke
authors.initials: T
authors.lastname: Takita
authors.forename: Miho
authors.initials: M
authors.lastname: Ohta
authors.forename: Kuniyo
authors.initials: K
authors.lastname: Inouye
mesh_terms: D000818:Animals; D001673:Biodegradation, Environmental; D002851:Chromatography, High Pressure Liquid; D019363:Cytochrome P-450 CYP1A1 / Q000235:genetics / Q000378:metabolism*; D019388:Cytochrome P-450 CYP1A2 / Q000235:genetics / Q000378:metabolism*; D004147:Dioxins / Q000378:metabolism; D004785:Environmental Pollutants / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D008861:Microsomes / Q000201:enzymology; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000378:metabolism*; D051381:Rats; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics
chemical_list: D004147:Dioxins; D004785:Environmental Pollutants; D000072317:Polychlorinated Dibenzodioxins; D011994:Recombinant Proteins; C000925:2,7-dichlorodibenzo-4-dioxin; D019363:Cytochrome P-450 CYP1A1; D019388:Cytochrome P-450 CYP1A2