12-oxophytodienoic-acid and cyclopentenone

13-lipoxygenases (13-LOX) catalyze the dioxygenation of various polyunsaturated fatty acids (PUFAs), of which α-linolenic acid (LeA) is converted to 13-S-hydroperoxyoctadeca-9, 11, 15-trienoic acid (13-HPOT), the precursor for the prostaglandin-like plant hormones cis-(+)-12-oxophytodienoic acid (12-OPDA) and methyl jasmonate (MJ). This study aimed for characterizing the four annotated

Topics: Acetates; Amino Acid Sequence; Arabidopsis; Arabidopsis Proteins; Cyclopentanes; Fatty Acids, Unsaturated; Gene Expression Regulation, Plant; Linoleic Acids; Lipoxygenase; Oxylipins

Green tissues of spikemoss Selaginella martensii Spring possessed the complex oxylipins patterns. Major oxylipins were the products of linoleic and α-linolenic acids metabolism via the sequential action of 13-lipoxygenase and divinyl ether synthase (DES) or allene oxide synthase (AOS). AOS products were represented by 12-oxophytodienoic acid (12-oxo-PDA) isomers. Exceptionally, S. martensii possesses high level of 12-oxo-9(13),15-PDA, which is very uncommon in flowering plants. Separate divinyl ethers were purified after micro-preparative incubations of linoleic or α-linolenic acids with homogenate of S. martensii aerial parts. The NMR data allowed us to identify all geometric isomers of divinyl ethers. Linoleic acid was converted to divinyl ethers etheroleic acid, (11Z)-etheroleic acid and a minority of (ω5Z)-etheroleic acid. With α-linolenate precursor, the specificity of divinyl ether biosynthesis was distinct. Etherolenic and (ω5Z)-etherolenic acids were the prevailing products while (11Z)-etherolenic acid was a minor one. Divinyl ethers are detected first time in non-flowering land plant. These are the first observations of fatty acid metabolism through the lipoxygenase pathway in spikemosses (Lycopodiophyta).

Topics: alpha-Linolenic Acid; Cyclopentanes; Cytochrome P-450 Enzyme System; Fatty Acids, Unsaturated; Intramolecular Oxidoreductases; Linoleic Acid; Lipoxygenase; Nuclear Magnetic Resonance, Biomolecular; Oxylipins; Plant Proteins; Selaginellaceae; Vinyl Compounds

Oxidized fatty acids, and particularly cyclopentenone oxylipins, are electrophilic metabolites that play diverse physiological roles. Current understanding is limited regarding how ion fragmentation provides essential information about oxylipin structures. In this work, unusual products of the collisional activation of deprotonated cyclopentenone oxylipins were investigated.. The cyclopentenone oxylipin 12-oxo-phytodienoic acid (OPDA) and its (18)O-labeled forms were ionized using negative-ion mode electrospray ionization, and product ion tandem mass (MS/MS) spectra were generated using collision-induced dissociation (CID). CID-MS/MS spectra were also generated for several cyclopentenone prostaglandins.. Upon collisional activation, deprotonated cyclopentenone oxylipins 12-oxo-phytodienoic acid (OPDA) and dinorOPDA form a characteristic and dominant product ion at m/z 165 that is attributed to charge-directed hydride migration to the electrophilic enone ring followed by elimination of neutral C7H10O2 from the carboxyl end. In contrast, pseudo-MS(3) spectra of deprotonated cyclopentenone prostaglandins exhibited a different fragmentation behavior, in that cleavage near C = C bonds is directed by the carbonyl group in the nearby cyclopentenone ring.. Two different routes of fragmentation are proposed for cyclopentenone fatty acids with saturated and unsaturated side chains. We predict that this behavior may facilitate the identification of novel cyclopentenone oxylipins and accelerate discoveries of their biological regulatory functions.

Topics: Anions; Cyclopentanes; Fatty Acids, Unsaturated; Oxylipins; Protons; Tandem Mass Spectrometry

A new approach to the synthesis of 4,5-disubstituted cyclopentenones is described. The strategy is based on the Pauson-Khand (PK) reaction of norbornadiene and N-Boc-propargylamine as an alkyne with a masked leaving group, which can be eliminated at will. This approach to the synthesis of 4,5-disubstituted cyclopentenones overcomes the problem of using the alkylation to introduce the α side chain. As an example, prostane 13-epi-12-oxo-phytodienoic acid (13-epi-12-oxo-PDA) methyl ester was synthesized.

Topics: Alkylation; Cyclopentanes; Fatty Acids, Unsaturated; Molecular Structure; Pargyline; Propylamines; Stereoisomerism

Jasmonates and phytoprostanes are oxylipins that regulate stress responses and diverse physiological and developmental processes. 12-Oxo-phytodienoic acid (OPDA) and phytoprostanes are structurally related electrophilic cyclopentenones, which activate similar gene expression profiles that are for the most part different from the action of the cyclopentanone jasmonic acid (JA) and its biologically active amino acid conjugates. Whereas JA-isoleucine signals through binding to COI1, the bZIP transcription factors TGA2, TGA5, and TGA6 are involved in regulation of gene expression in response to phytoprostanes. Here root growth inhibition and target gene expression were compared after treatment with JA, OPDA, or phytoprostanes in mutants of the COI1/MYC2 pathway and in different TGA factor mutants. Inhibition of root growth by phytoprostanes was dependent on COI1 but independent of jasmonate biosynthesis. In contrast, phytoprostane-responsive gene expression was strongly dependent on TGA2, TGA5, and TGA6, but not dependent on COI1, MYC2, TGA1, and TGA4. Different mutant and overexpressing lines were used to determine individual contributions of TGA factors to cyclopentenone-responsive gene expression. Whereas OPDA-induced expression of the cytochrome P450 gene CYP81D11 was primarily regulated by TGA2 and TGA5, the glutathione S-transferase gene GST25 and the OPDA reductase gene OPR1 were regulated by TGA5 and TGA6, but less so by TGA2. These results support the model that phytoprostanes and OPDA regulate differently (i) growth responses, which are COI1 dependent but jasmonate independent; and (ii) lipid stress responses, which are strongly dependent on TGA2, TGA5, and TGA6. Identification of molecular components in cyclopentenone signalling provides an insight into novel oxylipin signal transduction pathways.

Topics: Arabidopsis; Arabidopsis Proteins; Basic-Leucine Zipper Transcription Factors; Cyclopentanes; Cytochrome P-450 Enzyme System; Fatty Acids, Unsaturated; Gene Expression Regulation, Plant; Genes, Plant; Isoleucine; Nuclear Proteins; Oxylipins; Plant Roots; Plants, Genetically Modified; Prostaglandins A; Signal Transduction; Stress, Physiological; Transcription, Genetic; Transcriptome

Both enzymatically and non-enzymatically generated oxylipins fulfill signalling functions in plant responses to biotic and oxidative stress on the cellular level. We studied the impact of two different exogenously applied cyclopentenone-oxylipins on the proteome of Arabidopsis thaliana leaves: the enzymatically formed 12-oxo-phytodienoic-acid, a member of the jasmonate family of mediators, and A(1)-phytoprostane generated by a free-radical mechanism upon biotic and oxidative stress. Infiltration of leaves with these oxylipins led to induction of classical stress proteins like chaperones as well as enzymes connected to the cellular redox and detoxification systems. A large proportion of the regulated proteins are localized in chloroplasts where these oxylipins are formed. Furthermore, we show that cyclopentenone-oxylipins spontaneously react with several proteins and glutathione in vitro and in vivo. Conjugation to the glutathione sulfhydryl group is a reversible process that is also catalysed by glutathione-S-transferases. In vitro, an oxidative stress inducible glutathione-S-transferase, GST6, localized both in plastids and the cytosol can be covalently modified and partially inactivated by several cyclopentenone-oxylipins.

Topics: Arabidopsis; Arabidopsis Proteins; Chloroplasts; Cyclopentanes; Fatty Acids, Unsaturated; Glutathione Transferase; Molecular Chaperones; Oxidation-Reduction; Oxidative Stress; Oxylipins; Plant Leaves; Proteome; Signal Transduction

A novel group of cyclopentenone prostaglandin-like compounds, deoxy phytoprostanes J(1), together with their precursors, phytoprostanes D(1), were identified in tobacco, tomato and Arabidopsis. Previously, it was thought that 14,15-dehydro-12-oxo-phytodienoic acid, a member of the deoxy phytoprostanes J(1) family, is derived from either 12-oxo-phytodienoic acid or diketols via the allene oxide synthase pathway. Results suggest that 14,15-dehydro-12-oxo-phytodienoic acid as well as structurally related cyclopentenones of the chromomoric acid family are synthesized via the phytoprostane D(1) pathway in planta. Notably, 14,15-dehydro-12-oxo-phytodienoic acid is more abundant than 12-oxo-phytodienoic acid in all three species so far analyzed.

Topics: Arabidopsis; Catalysis; Chromatography, High Pressure Liquid; Cyclopentanes; Fatty Acids, Unsaturated; Nicotiana; Plant Extracts; Plant Growth Regulators; Solanum lycopersicum; Stereoisomerism

Formation of cyclopentenones was followed from linoleic, alpha-linolenic and gamma-linolenic acid hydroperoxides (HPOD, HPOT(alpha) and HPOT(gamma), respectively) via allene oxides in the presence of flax seed allene oxide synthase. Although 13-HPOT(alpha) and 9-HPOT(gamma) were effective cyclopentenone precursors, 13-HPOD, 9-HPOD(gamma) and 9-HPOT(alpha) were not. These results suggest that the presence of a double bond in beta, gamma-position toward the hydroperoxide function causes the strong effect of anchimeric assistance, increasing the cyclization rate by 2-3 orders of magnitude. The minor 15(E) isomer was formed from 13-HPOT along with usual 12-oxo-10,15(Z)-phytodienoic acid (12-oxo-PDA). The remarkable (about 2-fold) suppression of 12-oxo-PDA formation was observed under acidic (pH 5.5) conditions in comparison to the alkaline (pH 7.8) ones. The mechanism of double bond-assisted allene oxide cyclization, comprising dipolar pericyclic ring closure in zwitterionic intermediate, is proposed.

Topics: Carbon; Chromatography, High Pressure Liquid; Cyclopentanes; Ethylene Oxide; Fatty Acids; Fatty Acids, Unsaturated; Hydrogen-Ion Concentration; Intramolecular Oxidoreductases; Isomerases; Magnetic Resonance Spectroscopy; Molecular Structure; Oxidation-Reduction; Seeds