Linolenate 9R-Dioxygenase and Allene Oxide Synthase Activities of Lasiodiplodia theobromae
2012 (English)In: Lipids, ISSN 0024-4201, E-ISSN 1558-9307, Vol. 47, no 1, 65-73 p.Article in journal (Refereed) Published
Jasmonic acid (JA) is synthesized from linolenic acid (18:3n-3) by sequential action of 13-lipoxygenase, allene oxide synthase (AOS), and allene oxide cyclase. The fungus Lasiodiplodia theobromae can produce large amounts of JA and was recently reported to form the JA precursor 12-oxophytodienoic acid. The objective of our study was to characterize the fatty acid dioxygenase activities of this fungus. Two strains of L. theobromae with low JA secretion (~0.2 mg/L medium) oxygenated 18:3n-3 to 5,8-dihydroxy-9Z,12Z,15Z-octadecatrienoic acid as well as 9R-hydroperoxy-10E,12Z,15Z-octadecatrienoic acid, which was metabolized by an AOS activity into 9-hydroxy-10-oxo-12Z,15Z-octadecadienoic acid. Analogous conversions were observed with linoleic acid (18:2n-6). Studies using [11S-(2)H]18:2n-6 revealed that the putative 9R-dioxygenase catalyzed stereospecific removal of the 11R hydrogen followed by suprafacial attack of dioxygen at C-9. Mycelia from these strains of L. theobromae contained 18:2n-6 as the major polyunsaturated acid but lacked 18:3n-3. A third strain with a high secretion of JA (~200 mg/L) contained 18:3n-3 as a major fatty acid and produced 5,8-dihydroxy-9Z,12Z,15Z-octadecatrienoic acid from added 18:3n-3. This strain also lacked the JA biosynthetic enzymes present in higher plants.
Place, publisher, year, edition, pages
2012. Vol. 47, no 1, 65-73 p.
Natural Sciences Medical and Health Sciences
Research subject Biochemical Pharmacology
IdentifiersURN: urn:nbn:se:uu:diva-166341DOI: 10.1007/s11745-011-3622-5ISI: 000299532400008PubMedID: 22048860OAI: oai:DiVA.org:uu-166341DiVA: diva2:476310