title: Discovery of a Novel Linoleate Dioxygenase of Fusarium oxysporum and Linoleate Diol Synthase of Colletotrichum graminicola.
abstract: Fungal pathogens constitute serious threats for many forms of life. The pathogenic fungi Fusarium and Colletotrichum and their formae speciales (f. spp.) infect many types of crops with severe consequences and Fusarium oxysporum can also induce keratitis and allergic conditions in humans. These fungi code for homologues of dioxygenase-cytochrome P450 (DOX-CYP) fusion proteins of the animal heme peroxidase (cyclooxygenase) superfamily. The objective was to characterize the enzymatic activities of the DOX-CYP homologue of Colletotrichum graminicola (EFQ34869) and the DOX homologue of F. oxysporum (EGU79548). The former oxidized oleic and linoleic acids in analogy with 7,8-linoleate diol synthases (LDSs), but with the additional biosynthesis of 8,11-dihydroxylinoleic acid. The latter metabolized fatty acids to hydroperoxides with broad substrate specificity. It oxidized 20:4n-6 and 18:2n-6 to hydroperoxides with an R configuration at the (n-10) positions, and other n-6 fatty acids in the same way. [11S-(2)H]18:2n-6 was oxidized with retention and [11R-(2)H]18:2n-6 with loss of deuterium, suggesting suprafacial hydrogen abstraction and oxygen insertion. Fatty acids of the n-3 series were oxidized less efficiently and often to hydroperoxides with an R configuration at both (n-10) and (n-7) positions. The enzyme spans 1426 amino acids with about 825 residues in the N-terminal domain with DOX homology and 600 residues at the C-terminal domain without homology to other enzymes. We conclude that fungal oxylipins can be formed by two novel subfamilies of cyclooxygenase-related DOX.
authors.affiliation: Division of Biochemical Pharmacology, Department of Pharmaceutical Biosciences, Biomedical Center, Uppsala University, P.O. Box 591, SE-751 24, Uppsala, Sweden. linda.sooman@farmbio.uu.se.
authors.forename: Linda
authors.initials: L
authors.lastname: Sooman
authors.affiliation: Division of Biochemical Pharmacology, Department of Pharmaceutical Biosciences, Biomedical Center, Uppsala University, P.O. Box 591, SE-751 24, Uppsala, Sweden. Ernst.Oliw@farmbio.uu.se.
authors.forename: Ernst H
authors.initials: EH
authors.lastname: Oliw
mesh_terms: D000595:Amino Acid Sequence; D020231:Colletotrichum / Q000201:enzymology*; D017124:Conserved Sequence; D041961:Deuterium Exchange Measurement; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005670:Fusarium / Q000201:enzymology*; D019746:Intramolecular Oxidoreductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019787:Linoleic Acid / Q000378:metabolism; D008041:Linoleic Acids / Q000737:chemistry / Q000378:metabolism; D008054:Lipid Peroxides / Q000737:chemistry / Q000378:metabolism; D015394:Molecular Structure; D019301:Oleic Acid / Q000378:metabolism; D010084:Oxidation-Reduction; D010105:Oxygenases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013237:Stereoisomerism; D013379:Substrate Specificity
chemical_list: C000610520:8,11-dihydroxylinoleic acid; D005656:Fungal Proteins; D008041:Linoleic Acids; D008054:Lipid Peroxides; D011994:Recombinant Proteins; C075808:7,8-dihydroxylinoleic acid; D019301:Oleic Acid; D019787:Linoleic Acid; D010105:Oxygenases; C122014:linoleate diol synthase; D019746:Intramolecular Oxidoreductases; C021377:hydroperoxide isomerase
keywords: Cyclooxygenase; Cytochrome P450; Fatty acid oxidation; Heme peroxidase; Mass spectrometry; Oxylipin/biosynthesis