title: Epoxyalcohol synthase of Ectocarpus siliculosus. First CYP74-related enzyme of oxylipin biosynthesis in brown algae.
abstract: Enzymes of CYP74 family play the central role in the biosynthesis of physiologically important oxylipins in land plants. Although a broad diversity of oxylipins is known in the algae, no CYP74s or related enzymes have been detected in brown algae yet. Cloning of the first CYP74-related gene CYP5164B1 of brown alga Ectocarpus siliculosus is reported in present work. The recombinant protein was incubated with several fatty acid hydroperoxides. Linoleic acid 9-hydroperoxide (9-HPOD) was the preferred substrate, while linoleate 13-hydroperoxide (13-HPOD) was less efficient. α-Linolenic acid 9- and 13-hydroperoxides, as well as eicosapentaenoic acid 15-hydroperoxide were inefficient substrates. Both 9-HPOD and 13-HPOD were converted into epoxyalcohols. For instance, 9-HPOD was turned primarily into (9S,10S,11S,12Z)-9,10-epoxy-11-hydroxy-12-octadecenoic acid. Both epoxide and hydroxyl oxygen atoms of the epoxyalcohol were incorporated mostly from [18O2]9-HPOD. Thus, the enzyme exhibits the activity of epoxyalcohol synthase (EsEAS). The results show that the EsEAS isomerizes the hydroperoxides into epoxyalcohols via epoxyallylic radical, a common intermediate of different CYP74s and related enzymes. EsEAS can be considered as an archaic prototype of CYP74 family enzymes.
authors.affiliation: Kazan Institute of Biochemistry and Biophysics, Russian Academy of Sciences, P.O. Box 30, Kazan 420111, Russia.
authors.forename: Yana Y
authors.initials: YY
authors.lastname: Toporkova
authors.affiliation: Kazan Institute of Biochemistry and Biophysics, Russian Academy of Sciences, P.O. Box 30, Kazan 420111, Russia.
authors.forename: Valeria S
authors.initials: VS
authors.lastname: Fatykhova
authors.affiliation: Kazan Institute of Biochemistry and Biophysics, Russian Academy of Sciences, P.O. Box 30, Kazan 420111, Russia.
authors.forename: Yuri V
authors.initials: YV
authors.lastname: Gogolev
authors.affiliation: Kazan Institute of Biochemistry and Biophysics, Russian Academy of Sciences, P.O. Box 30, Kazan 420111, Russia.
authors.forename: Bulat I
authors.initials: BI
authors.lastname: Khairutdinov
authors.affiliation: Kazan Institute of Biochemistry and Biophysics, Russian Academy of Sciences, P.O. Box 30, Kazan 420111, Russia.
authors.forename: Lucia S
authors.initials: LS
authors.lastname: Mukhtarova
authors.affiliation: Kazan Institute of Biochemistry and Biophysics, Russian Academy of Sciences, P.O. Box 30, Kazan 420111, Russia. Electronic address: grechkin@kibb.knc.ru.
authors.forename: Alexander N
authors.initials: AN
authors.lastname: Grechkin
mesh_terms: D000595:Amino Acid Sequence; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004852:Epoxy Compounds / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism; D008041:Linoleic Acids / Q000378:metabolism; D008054:Lipid Peroxides / Q000378:metabolism; D054883:Oxylipins / Q000378:metabolism*; D000459:Phaeophyceae / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D016415:Sequence Alignment; D013379:Substrate Specificity; D017962:alpha-Linolenic Acid
chemical_list: C506899:9-hydroperoxy-10,12-octadecadienoic acid; D004852:Epoxy Compounds; D008041:Linoleic Acids; D008054:Lipid Peroxides; D054883:Oxylipins; D010940:Plant Proteins; D011994:Recombinant Proteins; D017962:alpha-Linolenic Acid; C038649:13-hydroperoxy-9,11-octadecadienoic acid; D003577:Cytochrome P-450 Enzyme System; D006861:Hydrogen Peroxide
keywords: Brown alga Ectocarpus siliculosus; CYP74 clan; Cytochrome P450; Epoxyalcohol synthase; Oxylipins