Discovery of a linoleate 9S-dioxygenase and an allene oxide synthase in a fusion protein of Fusarium oxysporum
2013 (English)In: Journal of Lipid Research, ISSN 0022-2275, E-ISSN 1539-7262, Vol. 54, no 12, 3417-3480 p.Article in journal (Refereed) Published
Fusarium oxysporum is a devastating plant pathogen that oxidizes C-18 fatty acids sequentially to jasmonates. The genome codes for putative dioxygenase (DOX)-cytochrome P450 (CYP) fusion proteins homologous to linoleate diol synthases (LDSs) and the allene oxide synthase (AOS) of Aspergillus terreus, e. g., FOXB_01332. Recombinant FOXB_01332 oxidized 18:2n-6 to 9S-hydroperoxy-10(E), 12(Z)-octadecadienoic acid by hydrogen abstraction and antarafacial insertion of molecular oxygen and sequentially to an allene oxide, 9S(10)-epoxy-10,12(Z)-octadecadienoic acid, as judged from nonenzymatic hydrolysis products (alpha- and gamma-ketols). The enzyme was therefore designated 9S-DOX-AOS. The 9S-DOX activity oxidized C-18 and C-20 fatty acids of the n-6 and n-3 series to hydroperoxides at the n-9 and n-7 positions, and the n-9 hydroperoxides could be sequentially transformed to allene oxides with only a few exceptions. The AOS activity was stereospecific for 9- and 11-hydroperoxides with S configurations. FOXB_01332 has acidic and alcoholic residues, Glu(946)-Val-Leu-Ser(949), at positions of crucial Asn and Gln residues (Asn-Xaa-Xaa-Gln) of the AOS and LDS. Site-directed mutagenesis studies revealed that FOXB_01332 and AOS of A. terreus differ in catalytically important residues suggesting that AOS of A. terreus and F. oxysporum belong to different subfamilies. FOXB_01332 is the first linoleate 9-DOX with homology to animal heme peroxidases and the first 9-DOX-AOS fusion protein.
Place, publisher, year, edition, pages
2013. Vol. 54, no 12, 3417-3480 p.
Biochemistry and Molecular Biology Other Natural Sciences
Research subject Pharmaceutical Biochemistry; Pharmaceutical Science
IdentifiersURN: urn:nbn:se:uu:diva-206088DOI: 10.1194/jlr.M044347ISI: 000330534900023OAI: oai:DiVA.org:uu-206088DiVA: diva2:644007