Linoleate and α-linolenate synthesis by isolated spinach (<i>Spinacia oleracea</i>) chloroplasts

Roughan, P. G.; Mudd, J.B.; McManus, T.T.; Slack, C. R.

doi:10.1042/bj1840571

Cited by 74 publications

(61 citation statements)

References 16 publications

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“…Even though further desaturation at both positions of Solanum MGD had produced a complex pattern, it had the same procaryotic pattern as shown by reversed-phase TLC (see below), since no C 18 chains were found at C-2. Previous studies with isolated spinach chloroplasts (14,18,20) resulted in the same distributions as those shown in Figure 3.…”

supporting

confidence: 66%

“…MGD of a similar fatty acid composition as shown in Figure 2 for peas was recently found to be synthesized in an independent study of pea chloroplasts (4) and by the combined action of the two acyltransferases in a reconstituted system from pea chloroplasts (5). Isolated spinach chloroplasts produced similar profiles of labeled fatty acids in various intermediates (14,18,20). In summary, the analysis of fatty acid composition does not reveal differences with regard to the fatty acids formed or incorporated during short-term incubations into lipids by 16:3 and 18:3 chloroplasts, since all DAG-containing lipids have about equal proportions of saturated and monoenoic acids.…”

mentioning

confidence: 84%

“…Prior to the present study, the ability of chloroplasts to desaturate MGD-bound acyl-chains has been demonstrated only with spinach chloroplasts (20). Identical experiments with chloroplasts from Solanum and Chenopodium confirmed the autonomy of these organelles in the production of trienoic acyl chains as components of de novo-synthesized MGD.…”

mentioning

confidence: 92%

“…The C-l position is occupied by C 18 fatty acids and to a small extent by C16 groups. The similarity in DAG backbones of lipids from blue-green algae (22, 30) with those synthesized by the chloroplast-confmed pathway in 16:3 plants suggests a phylogenetic relation and justifies the term procaryotic.The different pathways just mentioned were deduced from labeling experiments with leaves from a small selection of 18:3 and 16:3 plants (17,24,26,29), whereas studies with isolated chloroplasts were mainly confined to organelles from the 16:3 plant spinach (14,20). To provide additional evidence for the roles ascribed to chloroplasts in pro-or eucaryotic pathways during MGD biosynthesis in different plants, we carried out experiments with chloroplasts isolated from 18:3 as well as 16:3 plants.…”

mentioning

confidence: 99%

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Similarities and Differences in Lipid Metabolism of Chloroplasts Isolated from 18:3 and 16:3 Plants

Heinz¹,

Roughan²

1983

Plant Physiol.

261

167

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Photosynthetically active chloroplasts reting high rates of fatty acid synthesis from i1-"4Clacetate were purifie from leaves of both 16:3 (Solaum nodiforuu, Chenopodiwm album) and 183 plants (Amaranthu lividus, Pisum sativum). A comparson of lipids into which newly synthesized fatty acids were incorporated revealed that, in 183 chloroplasts, enzymic activities catalyzing the conversion of phosphatidate to diacylglycerol and of diacyiglycerol to monogalactosyl diacylglycerol (MGD) were significantiy less active than in 16:3 chloroplasts. In contrast, labeling rates of MGD from UDP-I14Cigal were similar for both types of chloroplasts. having two linoleoyl groups results in an accordingly unsaturated MGD. The MGD-linked acyl groups are substrates for the introduction of the third double bonds (16) to yield MGD with two linolenoyl residues. This galactolipid is characteristic of 18:3 plants such as Asteraceae and Fabaceae, for example (9). It is called eucaryotic MGD, because the nucleocytoplasmic part of the cell controls the construction of the DAG backbone which carries C 18 fatty acids at both C-1 and C-2 positions of glycerol (7), whereas C 16:0, if present, is excluded from C-2.In photosynthetically active cells of 16:3 plants which are represented, for example, by members of Apiaceae and Brassicaceae (9), two pathways operate in parallel (18) to provide thylakoids with MGD. The cooperative 'eucaryotic' sequence (4) is supplemented to various extents by a 'procaryotic' pathway. Its reactions are confined to the chloroplast and result in a typical arrangement of acyl groups as well as their complete desaturation once they are esterified to MGD. Procaryotic DAG backbones carry C 16:0 and its desaturation products at C-2 (7) from which position C18: fatty acids are excluded. The C-l position is occupied by C 18 fatty acids and to a small extent by C16 groups. The similarity in DAG backbones of lipids from blue-green algae (22, 30) with those synthesized by the chloroplast-confmed pathway in 16:3 plants suggests a phylogenetic relation and justifies the term procaryotic.The different pathways just mentioned were deduced from labeling experiments with leaves from a small selection of 18:3 and 16:3 plants (17,24,26,29), whereas studies with isolated chloroplasts were mainly confined to organelles from the 16:3 plant spinach (14,20). To provide additional evidence for the roles ascribed to chloroplasts in pro-or eucaryotic pathways during MGD biosynthesis in different plants, we carried out experiments with chloroplasts isolated from 18:3 as well as 16:3 plants. Our data suggest that chloroplasts from these two groups of plants have similarities and differences in enzymic equipment explaining some of the above mentioned complications in lipid biosynthesis. Chloroplast Isolation. The medium (12) used for isolating chloroplasts, forming gradients, measuring O2 evolution and lipid synthesis contained 25 mm Hepes, 10 mm KHCO3, 2 mm EDTA, 1 mM MgCl2, 1 mm MnCl2, 0.3 mm KH2PO4, and 0.33 M sorbitol, adjusted to ...

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supporting

confidence: 66%

mentioning

confidence: 84%

mentioning

confidence: 92%

mentioning

confidence: 99%

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Similarities and Differences in Lipid Metabolism of Chloroplasts Isolated from 18:3 and 16:3 Plants

Heinz¹,

Roughan²

1983

Plant Physiol.

261

167

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“…monogalactosyldiacylglycerol, digalactosyldiacylglycerol, and sulfolipid (Douce and Joyard, 1990;Browse and Somerville, 1991). In the "prokaryotic" pathway, 16:O at the sn-2 position of glycerolipids may be desaturated to 16:l-trans (on phosphatidylglycerol) (Sparace and Mudd, 1982) or to 16:3 (on monogalactosyldiacylglycerol) (Roughan et al, 1979;Heinz and Roughan, 1983).…”

mentioning

confidence: 99%

A Mutant of Arabidopsis Deficient in the Elongation of Palmitic Acid

James

Dooner

et al. 1994

Plant Physiol.

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The overall fatty acid composition of leaf lipids in a mutant of Arabidopsis thaliana was characterized by an increased level of 160 and a concomitant decrease of 18-carbon fatty acids as a consequence of a single recessive nuclear mutation at the fabl In all plants studied, de novo fatty acid synthesis occurs in the chloroplasts or plastids of the cell (Ohlrogge et al., 1991) by the action of a dissociable type I1 fatty acid synthase (Browse and Somerville, 1991). The primary product of fatty acid synthesis, 16:O-ACP, can undergo one of three competing reactions: (a) hydrolysis by acyl-ACP thioesterase, (b) elongation to 18:O-ACP (which is followed by nearly quantitative desaturation to form 18:1-ACP), or (c) transfer to lysophosphatidic acid. Therefore, the ratio of 16-carbon to 18-carbon fatty acids in the membrane lipids could be determined by the relative fluxes through these three reactions. The significance of these reactions is related to the two pathways that are available for the synthesis of membrane glycerolipids in the leaf cells of higher plants (Browse and Somerville, 1991).In Arabidopsis thaliana, the "prokaryotic" pathway (Roughan and Slack, 1982), located in the chloroplast envelope, uses 18:l-ACP and 16:O-ACP for the sequential acylation of glycerol-3-P to form phosphatidic acid. The phosphatidic acid made by the prokaryotic pathway has 18:l at the sn-1 position and 16:O at the sn-2 position of the glycerol '

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Identification of sulfoglycolipids from the alga Porphyridium purpureum by matrix‐assisted laser desorption/ionisation quadrupole ion trap time‐of‐flight mass spectrometry

Naumann

Darsow

Walter

et al. 2007

Rapid Comm Mass Spectrometry

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Sulfoglycolipids, isolated from different phototrophic organisms, particularly plants and algae, have already been identified as bioactive compounds. In addition to their antiviral activity their influence on the immune response in mammalian cells is the focus of many studies. For the first time it has been possible to investigate purified sulfoquinovosyldiacylglycerols (SQDGs) from the microalga Porphyridium purpureum by matrix-assisted laser desorption/ionisation (MALDI) in the negative ion reflectron mode. Thereby, different solid and ionic liquid matrices have been tested to improve signal intensity during the laser ionisation. By using the MALDI Trap time-of-flight (ToF) multiple-stage (MS(n)) hybrid mass spectrometer the fatty acid compositions of the SQDGs were analysed by MS, and confirmed by MS(2) and MS(3) experiments. Thereby, hexadecanoic acid (C16:0), octadecadienoic acid (C18:2), eicosatetraenoic acid (C20:4), and eicosapentaenoic acid (C20:5) were detected in the purified fraction of SQDGs. The localisation of hexadecanoic acid (C16:0) at the sn-2 position, and unsaturated fatty acids at the sn-1 position of the SQDGs, determined by specific enzymatic hydrolysis, marks a procaryotic biosynthesis of SQDGs in the eucaryotic alga cells.

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Linoleate and α-linolenate synthesis by isolated spinach (Spinacia oleracea) chloroplasts

Cited by 74 publications

References 16 publications

Similarities and Differences in Lipid Metabolism of Chloroplasts Isolated from 18:3 and 16:3 Plants

Similarities and Differences in Lipid Metabolism of Chloroplasts Isolated from 18:3 and 16:3 Plants

A Mutant of Arabidopsis Deficient in the Elongation of Palmitic Acid

Identification of sulfoglycolipids from the alga Porphyridium purpureum by matrix‐assisted laser desorption/ionisation quadrupole ion trap time‐of‐flight mass spectrometry

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