Recombinant Soybean Lipoxygenase 2 (GmLOX2) Acts Primarily as a ω6()-Lipoxygenase.

The lipoxygenase (LOX) cascade is a source of bioactive oxylipins that play a regulatory role in plants, animals, and fungi. Soybean ( (L.) Merr.

Detection and identification of complex oxylipins in meadow buttercup (Ranunculus acris) leaves.

Screening of linolipins, i.e. galactolipids containing esterified residues of divinyl ether oxylipins, in the leaves of several higher plants revealed the presence of these complex oxylipins in the meadow buttercup leaves.

Oxylipin biosynthesis in spikemoss Selaginella moellendorffii: Molecular cloning and identification of divinyl ether synthases CYP74M1 and CYP74M3.

Nonclassical P450s of CYP74 family control the secondary conversions of fatty acid hydroperoxides to bioactive oxylipins in plants. At least ten genes attributed to four novel CYP74 subfamilies have been revealed by the recent sequencing of the spikemoss Selaginella moellendorffii Hieron genome. Two of these genes CYP74M1 and CYP74M3 have been cloned in the present study.

Detection and molecular cloning of CYP74Q1 gene: identification of Ranunculus acris leaf divinyl ether synthase.

Enzymes of the CYP74 family, including the divinyl ether synthase (DES), play important roles in plant cell signalling and defence. The potent DES activities have been detected before in the leaves of the meadow buttercup (Ranunculus acris L.) and few other Ranunculaceae species.

Isolation and structure elucidation of linolipins C and D, complex oxylipins from flax leaves.

Two complex oxylipins (linolipins C and D) were isolated from the leaves of flax plants inoculated with phytopathogenic bacteria Pectobacterium atrosepticum. Their structures were elucidated based on UV, MS and NMR spectroscopic data. Both oxylipins were identified as digalactosyldiacylglycerol (DGDG) molecular species.

Green leaf divinyl ether synthase: gene detection, molecular cloning and identification of a unique CYP74B subfamily member.

Enzymes of the CYP74 family (P450 superfamily) play a key role in the plant lipoxygenase signalling cascade. Recently we detected a pathogen inducible divinyl ether synthase (DES) in flax leaves [Chechetkin, Blufard, Hamberg, Grechkin, 2008]. This prompted us to examine the CYP74 genes in the flax leaf transcriptome.

Unprecedented pathogen-inducible complex oxylipins from flax--linolipins A and B.

Oxylipins constitute a large family of bioregulators, biosynthesized via unsaturated fatty acid oxidation. This study reports the detection of an unprecedented family of complex oxylipins from flax leaves. Two major members of this family, compounds 1 and 2, were isolated and purified.

A lipoxygenase-divinyl ether synthase pathway in flax (Linum usitatissimum L.) leaves.

Incubation of linoleic acid with an enzyme preparation from leaves of flax (Linum usitatissimum L.) led to the formation of a divinyl ether fatty acid, i.e.

Evidence for communality in the primary determinants of CYP74 catalysis and of structural similarities between CYP74 and classical mammalian P450 enzymes.

In silico structural analysis of CYP74C3, a membrane-associated P450 enzyme from the plant Medicago truncatula (barrel medic) with hydroperoxide lyase (HPL) specificity, showed that it had strong similarities to the structural folds of the classical microsomal P450 enzyme from rabbits (CYP2C5). It was not only the secondary structure predictions that supported the analysis but site directed mutagenesis of the substrate interacting residues was also consistent with it. This led us to develop a substrate-binding model of CYP74C3 which predicted three amino acid residues, N285, F287, and G288 located in the putative I-helix and distal haem pocket of CYP74C3 to be in close proximity to the preferred substrate 13-HPOTE.

Synthesis of 3-oxalinolenic acid and beta-oxidation-resistant 3-oxa-oxylipins.

3-Oxalinolenic acid (3-oxa-9(Z),12(Z),15(Z)-octadecatrienoic acid or (6(Z),9(Z),12(Z)-pentadecatrienyloxy)acetic acid) was synthesized from 5(Z),8(Z),11(Z),14(Z),17(Z)-eicosapentaenoic acid by a sequence involving the C15 aldehyde 3(Z),6(Z),9(Z),12(Z)-pentadecatetraenal as a key intermediate. Conversion of the aldehyde by isomerization and two steps of reduction afforded 6(Z),9(Z),12(Z)-pentadecatrienol, which was coupled to bromoacetate to afford after purification by HPLC >99%-pure 3-oxalinolenic acid in 10-15% overall yield. 3-Oxalinolenic acid was efficiently oxygenated by soybean lipoxygenase-1 into 3-oxa-13(S)-hydroperoxy-9(Z),11(E),15(Z)-octadecatrienoic acid, and this hydroperoxide could be further converted chemically into 3-oxa-13(S)-hydroxy-9(Z),11 (E),15(Z)-octadecatrienoic acid and 3-oxa-13-oxo-9(Z),11 (E),15(Z)-octadecatrienoic acid.

The novel pathway for ketodiene oxylipin biosynthesis in Jerusalem artichoke (Helianthus tuberosus) tubers.

The new route of the plant lipoxygenase pathway, directed specifically towards the ketodiene formation, was detected during in vitro experiments with Jerusalem artichoke (Helianthus tuberosus) tubers. Through this pathway (9Z,11E,13S)-13-hydroperoxy-9,11-octadecadienoic acid (13-HPOD) is reduced to corresponding 13-hydroxy acid (13-HOD), which is in turn dehydrogenated into ketodiene (9Z,11E,13S)-13-oxo-9,11-octadecadienoic acid (13-KOD). Dehydrogenation of 13-HOD into 13-KOD was not dependent on the presence of either NAD or NADP, but was strongly dependent on the presence of oxygen.

Role of structure and pH in cyclization of allene oxide fatty acids: implications for the reaction mechanism.

Incubations of allene oxide synthases of flax or maize with the E,E-isomers of the 13- and 9-hydroperoxides of linoleic acid (E,E-13- and E,E-9-HPOD, respectively) at pH 7.5 afforded substantial yields of trans-disubstituted cyclopentenones. Under the conditions used, (Z,E)-HPODs were converted mainly into alpha-ketols and afforded only trace amount of cyclopentenones.