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标题：An allene oxide and 12-oxophytodienoic acid are key intermediates in jasmonic acid biosynthesis by Fusarium oxysporum
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作者：Ernst H. Oliw ; Mats Hamberg
期刊名称：JLR Papers In Press
印刷版ISSN：0022-2275
电子版ISSN：1539-7262
出版年度：2017
卷号：58
期号：8
页码：1670-1680
DOI：10.1194/jlr.M077305
语种：English
出版社：American Society for Biochemistry and Molecular Biology
摘要：Fungi can produce jasmonic acid (JA) and its isoleucine conjugate in large quantities, but little is known about the biosynthesis. Plants form JA from 18:3 n -3 by 13 S -lipoxygenase (LOX), allene oxide synthase, and allene oxide cyclase. Shaking cultures of Fusarium oxysporum f. sp. tulipae released over 200 mg of jasmonates per liter. Nitrogen powder of the mycelia expressed 10 R -dioxygenase-epoxy alcohol synthase activities, which was confirmed by comparison with the recombinant enzyme. The 13 S -LOX of F. oxysporum could not be detected in the cell-free preparations. Incubation of mycelia in phosphate buffer with [17,17,18,18,18-²H₅]18:3 n -3 led to biosynthesis of a [²H₅]12-oxo-13-hydroxy-9 Z ,15 Z -octadecadienoic acid (α-ketol), [²H₅]12-oxo-10,15 Z -phytodienoic acid (12-OPDA), and [²H₅]13-keto- and [²H₅]13 S -hydroxyoctadecatrienoic acids. The α-ketol consisted of 90% of the 13 R stereoisomer, suggesting its formation by nonenzymatic hydrolysis of an allene oxide with 13 S configuration. Labeled and unlabeled 12-OPDA were observed following incubation with 0.1 mM [²H₅]18:3 n -3 in a ratio from 0.4:1 up to 47:1 by mycelia of liquid cultures of different ages, whereas 10 times higher concentration of [²H₅]13 S -hydroperoxyoctadecatrienoic acid was required to detect biosynthesis of [²H₅]12-OPDA. The allene oxide is likely formed by a cytochrome P450 or catalase-related hydroperoxidase. We conclude that F. oxysporum , like plants, forms jasmonates with an allene oxide and 12-OPDA as intermediates.
关键词：cytochrome P450 ; epoxy alcohol synthase ; fatty acid dioxygenase ; jasmonates ; lipids/oxidation ; lipoxygenase ; mass spectrometry ; methods/high-performance liquid chromatography