title: Mammalian ALOX15 orthologs exhibit pronounced dual positional specificity with docosahexaenoic acid.
abstract: Mammalian lipoxygenases (LOX) have been implicated in cell differentiation and in the pathogenesis of inflammatory, hyperproliferative and neurological diseases. Although the reaction specificity of mammalian LOX with n-6 fatty acids (linoleic acid, arachidonic acid) has been explored in detail little information is currently available on the product patterns formed from n-3 polyenoic fatty acids, which are of particular nutritional importance and serve as substrate for the biosynthesis of pro-resolving inflammatory mediators such as resolvins and maresins. Here we expressed the ALOX15 orthologs of eight different mammalian species as well as human ALOX12 and ALOX15B as recombinant his-tag fusion proteins and characterized their reaction specificity with the most abundantly occurring polyunsaturated fatty acids (PUFAs) including 5,8,11,14,17-eicosapentaenoic acid (EPA) and 4,7,10,13,16,19-docosahexaenoic acid (DHA). We found that the LOX isoforms tested accept these fatty acids as suitable substrates and oxygenate them with variable positional specificity to the corresponding n-6 and n-9 hydroperoxy derivatives. Surprisingly, human ALOX15 as well as the corresponding orthologs of chimpanzee and orangutan, which oxygenates arachidonic acid mainly to 15S-H(p)ETE, exhibit a pronounced dual reaction specificity with DHA forming similar amounts of 14- and 17-H(p)DHA. Moreover, ALOX15 orthologs prefer DHA and EPA over AA when equimolar concentrations of n-3 and n-6 PUFA were supplied simultaneously. Taken together, these data indicate that the reaction specificity of mammalian LOX isoforms is variable and strongly depends on the chemistry of fatty acid substrates. Most mammalian ALOX15 orthologs exhibit dual positional specificity with highly unsaturated n-3 polyunsaturated fatty acids.
authors.affiliation: Institute for Food Toxicology, University of Veterinary Medicine Hannover, Bischofsholer Damm 15, 30173 Hannover, Germany.
authors.forename: Laura
authors.initials: L
authors.lastname: Kutzner
authors.affiliation: Institute of Biochemistry, University Medicine Berlin - Charité, Charitéplatz 1, 10117 Berlin, Germany.
authors.forename: Kateryna
authors.initials: K
authors.lastname: Goloshchapova
authors.affiliation: Institute of Biochemistry, University Medicine Berlin - Charité, Charitéplatz 1, 10117 Berlin, Germany.
authors.forename: Dagmar
authors.initials: D
authors.lastname: Heydeck
authors.affiliation: Institute of Biochemistry, University Medicine Berlin - Charité, Charitéplatz 1, 10117 Berlin, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Stehling
authors.affiliation: Institute of Biochemistry, University Medicine Berlin - Charité, Charitéplatz 1, 10117 Berlin, Germany. Electronic address: hartmut.kuehn@charite.de.
authors.forename: Hartmut
authors.initials: H
authors.lastname: Kuhn
authors.affiliation: Institute for Food Toxicology, University of Veterinary Medicine Hannover, Bischofsholer Damm 15, 30173 Hannover, Germany; Faculty of Mathematics and Natural Sciences, Food Chemistry Department, University of Wuppertal, Gaussstrasse 20, 42119 Wuppertal, Germany.
authors.forename: Nils Helge
authors.initials: NH
authors.lastname: Schebb
mesh_terms: D000818:Animals; D001093:Arachidonate 15-Lipoxygenase / Q000378:metabolism*; D004281:Docosahexaenoic Acids / Q000378:metabolism*; D015118:Eicosapentaenoic Acid / Q000378:metabolism; D015525:Fatty Acids, Omega-3 / Q000378:metabolism; D043371:Fatty Acids, Omega-6 / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D006801:Humans; D008322:Mammals / Q000378:metabolism*; D012680:Sensitivity and Specificity
chemical_list: D015525:Fatty Acids, Omega-3; D043371:Fatty Acids, Omega-6; D005231:Fatty Acids, Unsaturated; D004281:Docosahexaenoic Acids; D015118:Eicosapentaenoic Acid; D001093:Arachidonate 15-Lipoxygenase
keywords: Eicosanoids; Inflammation; Leukotrienes; Polyunsaturated fatty acids; Reaction specificity; Resolvins