scholarly journals Detection of the First Epoxyalcohol Synthase/Allene Oxide Synthase (CYP74 Clan) in the Lancelet (Branchiostoma belcheri, Chordata)

2021 ◽  
Vol 22 (9) ◽  
pp. 4737
Author(s):  
Yana Y. Toporkova ◽  
Elena O. Smirnova ◽  
Natalia V. Lantsova ◽  
Lucia S. Mukhtarova ◽  
Alexander N. Grechkin
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Oxidative Metabolism ◽  
Octadecadienoic Acid ◽  
Cytochromes P450 ◽  
Allene Oxide ◽  
Allene Oxide Synthase ◽  
Branchiostoma Belcheri ◽  
Oxide Synthase ◽  
Fatty Acid Hydroperoxides

The CYP74 clan cytochromes (P450) are key enzymes of oxidative metabolism of polyunsaturated fatty acids in plants, some Proteobacteria, brown and green algae, and Metazoa. The CYP74 enzymes, including the allene oxide synthases (AOSs), hydroperoxide lyases, divinyl ether synthases, and epoxyalcohol synthases (EASs) transform the fatty acid hydroperoxides to bioactive oxylipins. A novel CYP74 clan enzyme CYP440A18 of the Asian (Belcher’s) lancelet (Branchiostoma belcheri, Chordata) was biochemically characterized in the present work. The recombinant CYP440A18 enzyme was active towards all substrates used: linoleate and α-linolenate 9- and 13-hydroperoxides, as well as with eicosatetraenoate and eicosapentaenoate 15-hydroperoxides. The enzyme specifically converted α-linolenate 13-hydroperoxide (13-HPOT) to the oxiranyl carbinol (9Z,11R,12R,13S,15Z)-11-hydroxy-12,13-epoxy-9,15-octadecadienoic acid (EAS product), α-ketol, 12-oxo-13-hydroxy-9,15-octadecadienoic acid (AOS product), and cis-12-oxo-10,15-phytodienoic acid (AOS product) at a ratio of around 35:5:1. Other hydroperoxides were converted by this enzyme to the analogous products. In contrast to other substrates, the 13-HPOT and 15-HPEPE yielded higher proportions of α-ketols, as well as the small amounts of cyclopentenones, cis-12-oxo-10,15-phytodienoic acid and its higher homologue, dihomo-cis-12-oxo-3,6,10,15-phytotetraenoic acid, respectively. Thus, the CYP440A18 enzyme exhibited dual EAS/AOS activity. The obtained results allowed us to ascribe a name “B. belcheri EAS/AOS” (BbEAS/AOS) to this enzyme. BbEAS/AOS is a first CYP74 clan enzyme of Chordata species possessing AOS activity.

Regulation of oxylipin synthesis

2000 ◽  
Vol 28 (6) ◽  
pp. 847-849 ◽  
Author(s):  
D. F. Hildebrand ◽  
M. Afitlhile ◽  
H. Fukushige
Keyword(s):  
Fatty Acids ◽  
Plant Species ◽  
Citrullus Lanatus ◽  
Product Formation ◽  
Hydroperoxide Lyase ◽  
Allene Oxide ◽  
Allene Oxide Synthase ◽  
Esterified Fatty Acids ◽  
Oxide Synthase ◽  
Fatty Acid Hydroperoxides

Two very common groups of oxylipins formed in plants involve the conversion of fatty acid hydroperoxides, such as hydroperoxy-octadecatrienoic acid, into further metabolites by allene oxide synthase and hydroperoxide lyase. Both of these oxylipin branch pathways appear to be ubiquitous or nearly so in plants, but the relative activities of these two branches vary among plant species. In most plants examined, including Arabidopsis product formation from either of these pathways is minimal until elicited by wounding or some other means, upon which products from both pathways, such as jasmonic acid and C6 aldehydes and alcohols, can increase by orders of magnitude. In some plant species such as Artemisia and Jasminum spp. oxylipin product formation is heavily skewed towards allene oxide synthase products. Others such as watermelon (Citrullus lanatus) produce 10-fold higher amounts or more of hydroperoxide lyase than allene oxide synthase products. Arabidopsis and tobacco are intermediate between these extremes. Artemisia and Jasminum are also unusual in that they do not require wounding or other types of induction for high oxylipin product formation. Release of non-esterified fatty acids appears to be correlated with oxylipin formation, but phospholipase A2 appears not to be involved with oxylipin production, at least in the case of Artemisia leaves.

scholarly journals The lipoxygenase pathway in tulip (Tulipa gesneriana): detection of the ketol route

2000 ◽  
Vol 352 (2) ◽  
pp. 501-509 ◽  
Author(s):  
Alexander N. GRECHKIN ◽  
Lucia S. MUKHTAROVA ◽  
Mats HAMBERG
Keyword(s):  
Octadecadienoic Acid ◽  
Optical Purity ◽  
Cyclase Activity ◽  
Allene Oxide ◽  
Allene Oxide Synthase ◽  
Lipoxygenase Pathway ◽  
Tulipa Gesneriana ◽  
Tulip Bulbs ◽  
Oxide Synthase

The in vitro metabolism of [1-14C]linoleate, [1-14C]linolenate and their 9(S)-hydroperoxides was studied in cell-free preparations from tulip (Tulipa gesneriana) bulbs, leaves and flowers. Linoleate and its 9-hydroperoxide were converted by bulb and leaf preparations into three ketols: (12Z)-9-hydroxy-10-oxo-12-octadecadienoic acid (α-ketol), (11E)-10-oxo-13-hydroxy-11-octadecadienoic acid (γ-ketol) and a novel compound, (12Z)-10-oxo-11-hydroxy-12-octadecadienoic acid (10,11-ketol), in the approximate molar proportions of 10:3:1. The corresponding 15,16-dehydro α- and γ-ketols were the main metabolites of [1-14C]linolenate and its 9-hydroperoxide. Thus bulbs and leaves possessed 9-lipoxygenase and allene oxide synthase activities. Incubations with flower preparations gave α-ketol hydro(pero)xides as predominant metabolites. Bulb and leaf preparations possessed a novel enzyme activity, γ-ketol reductase, which reduces γ-ketol to 10-oxo-13-hydroxyoctadecanoic acid (dihydro-γ-ketol) in the presence of NADH. Exogenous linolenate 13(S)-hydroperoxide was converted mostly into chiral (9S,13S)-12-oxo-10-phytodienoate (99.5% optical purity) by bulb preparations, while [1-14C]linolenate was a precursor for ketols only. Thus tulip bulbs possess abundant allene oxide cyclase activity, the substrate for which is linolenate 13(S)-hydroperoxide, even though 13(S)-lipoxygenase products were not detectable in the bulbs. The majority of the cyclase activity was found in the microsomes (105g pellet). Cyclase activity was not found in the other tissues examined, but only in the bulbs. The ketol route of the lipoxygenase pathway, mediated by 9-lipoxygenase and allene oxide synthase activities, has not been detected previously in the vegetative organs of any plant species.

Lipoxygenase pathway in tulip: biosynthesis of ketols

2000 ◽  
Vol 28 (6) ◽  
pp. 851-853 ◽  
Author(s):  
A. N. Grechkin ◽  
L. S. Mukhtarova ◽  
M. Hamberg
Keyword(s):  
Octadecadienoic Acid ◽  
Allene Oxide ◽  
The Novel ◽  
Allene Oxide Synthase ◽  
Allene Oxide Cyclase ◽  
Lipoxygenase Pathway ◽  
Tulipa Gesneriana ◽  
Oxide Synthase

The metabolism in vitro of [1-14C]linoleate, [1-14C]linolenate and their 9(S)-hydroperoxides in tulip (Tulipa gesneriana) was found to be under the control of 9-lipoxygenase and allene oxide synthase, and directed towards α-ketol, γ-ketol and the novel compound (12Z)-10-oxo-11-hydroxy- 12-octadecadienoic acid (10,11-ketol). Potent activity of allene oxide cyclase (in bulbs) and a new enzyme, γ-ketol reductase (in bulbs and leaves), was detected. Metabolism in flowers is directed predominantly towards α-ketol hydroperoxide.

scholarly journals Developing a platform for production of the oxylipin KODA 9-hydroxy-10-oxo-octadecadienoic acid in plants

2021 ◽  
Author(s):  
Yuta Ihara ◽  
Takayuki Wakamatsu ◽  
Mineyuki Yokoyama ◽  
Daisuke Maezawa ◽  
Hiroyuki Ohta ◽  
...  
Keyword(s):  
Crop Production ◽  
Aquatic Plant ◽  
Octadecadienoic Acid ◽  
Ectopic Expression ◽  
Allene Oxide ◽  
Allene Oxide Synthase ◽  
Leaf Extracts ◽  
Oxide Synthase ◽  
Endogenous Lipids

Abstract KODA (9-hydroxy-10-oxo-12(Z),15(Z)-octadecadienoic acid) is a plant oxylipin involved in recovery from stress. As an agrichemical, KODA helps maintain crop production under various environmental stresses. In plants, KODA is synthesized from α-linolenic acids via 9-lipoxygenase (9-LOX) and allene oxide synthase (AOS), although the amount is usually low except in the free-floating aquatic plant Lemna paucicostata. To improve KODA biosynthetic yield in other plants such as Nicotiana benthamiana and Arabidopsis thaliana, we developed a system to overproduce KODA in vivo via ectopic expression of L. paucicostata 9-LOX and AOS. The transient expression in N. benthamiana showed that the expression of these two genes is sufficient to produce KODA in leaves. However, stable expression of 9-LOX and AOS (with consequent KODA production) in Arabidopsis plants succeeded only when the two proteins were localized in plastids or the endoplasmic reticulum/lipid droplets. Although only small amounts of KODA could be detected in leaf extracts of transgenic Nicotiana or Arabidopsis plants, subsequent incubation of the extracts increased KODA abundance over time. Therefore, KODA production in transgenic plants stably expressing 9-LOX and AOS requires specific subcellular localization of these two enzymes and incubation of leaf crude extracts, which liberates α-linolenic acid via breakdown of endogenous lipids.

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