Discovery of a Novel Linoleate Dioxygenase of Fusarium oxysporum and Linoleate Diol Synthase of Colletotrichum graminicola

• Published in: Lipids 2015-12, Vol.50 (12), p.1243-1252
• Main Authors: Sooman, Linda, Oliw, Ernst H
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Amino acids; animal proteins; Biomedical and Life Sciences; Biosynthesis; Colletotrichum; Colletotrichum - enzymology; Colletotrichum graminicola; Conserved Sequence; crops; Cyclooxygenase; Cytochrome P450; Deuterium; Deuterium Exchange Measurement; Enzymatic activity; enzyme activity; Fatty acid oxidation; Fatty acids; Fungal Proteins - chemistry; Fungal Proteins - genetics; Fungal Proteins - metabolism; fungi; Fusarium - enzymology; Fusarium oxysporum; Glomerella graminicola; Heme peroxidase; humans; hydroperoxides; Intramolecular Oxidoreductases - chemistry; Intramolecular Oxidoreductases - genetics; Intramolecular Oxidoreductases - metabolism; keratitis; Life Sciences; linoleic acid; Linoleic Acid - metabolism; Linoleic Acids - chemistry; Linoleic Acids - metabolism; Lipid Peroxides - chemistry; Lipid Peroxides - metabolism; Lipidology; Mass spectrometry; Medical Biochemistry; Medicinal Chemistry; Microbial Genetics and Genomics; Molecular Structure; Neurochemistry; Nutrition; Oleic Acid - metabolism; omega-3 fatty acids; omega-6 fatty acids; Original Article; Oxidation-Reduction; oxygen; Oxygenases - chemistry; Oxygenases - genetics; Oxygenases - metabolism; Oxylipin/biosynthesis; oxylipins; pathogens; peroxidase; Phylogeny; prostaglandin synthase; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism; Sequence Homology, Amino Acid; Stereoisomerism; Substrate Specificity
• ISSN: 0024-4201; 1558-9307; 1558-9307
• DOI: 10.1007/s11745-015-4078-9

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-²H]18:2n-6 was oxidized with retention and [11R-²H]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.