Biosynthesis of Phosphatidylethanolamine by Enzyme Preparations from Plant Tissues

Macher, Bruce A.; Mudd, J.B.

doi:10.1104/pp.53.2.171

Cited by 45 publications

(21 citation statements)

References 36 publications

(31 reference statements)

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“…PtdEA is a major phospholipid of higher plants (30, 32) and an ethanolamine-phosphotransferase capable of catalzying reaction 9 is well known (25,29,30). However, the cytidylyltransferase catalyzing reaction 8 has been mentioned only very briefly as present in enzyme preparations from carrot root (20), and subsequent attempts in at least two laboratories to demonstrate this activity in extracts of higher plants were unsuccessful (25-27).…”

Section: Introductionmentioning

confidence: 99%

“…Net synthesis of PtdSerine, which could provide the starting point for the above cycle, can be carried out by the combined actions of phosphatidatecytidylyltransferase [reaction (4) PtdEA is a major phospholipid of higher plants (30,32) and an ethanolamine-phosphotransferase capable of catalzying reaction 9 is well known (25,29,30). However, the cytidylyltransferase catalyzing reaction 8 has been mentioned only very briefly as present in enzyme preparations from carrot root (20), and subsequent attempts in at least two laboratories to demonstrate this activity in extracts of higher plants were unsuccessful (25)(26)(27). Radiolabeled EA is incorporated into PtdEA (1 1,26,27,33,38,39).…”

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confidence: 99%

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Synthesis of Ethanolamine and Its Regulation in Lemna paucicostata

Mudd¹,

Datko²

1989

Plant Physiol.

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The metabolism of ethanolamine and its derivatives in Lemna paucicostata has been investigated, with emphasis on the pathway for synthesis of phosphoethanolamine, a precursor of phosphatidylcholine in higher plants. In experiments involving labeling of intact plants with radioactive serine, ambiguities of interpretation due to entry of radioactivity into methyl groups of methylated ethanolamine derivatives were mitigated by pregrowth of plants with methionine. Difficulties due to labeling of diacylglyceryl moieties of phospholipids were avoided by acid hydrolysis of crucial samples and determination of radioactivity in isolated serine or ethanolamine moieties. The results obtained from such experiments are most readily reconciled with the biosynthetic sequence: seine --ethanolamine --phosphoethanolamine phosphatidylethanolamine. A possible altemative is: serine phosphatidylserine -. phosphatidylethanolamine -i ethanolamine --phosphoethanolamine. Cell-free extracts of L. paucicostata were shown to produce CO2 from the carbon originating as C-1 of serine at a rate sufficient to satisfy the demand for ethanolamine moieties. A number of experiments produced no support for a hypothetical role for phosphoserine in phosphoethanolamine formation. Uptake of exogenous ethanolamine commensurately down-regulates the synthesis of ethanolamine moieties (considered as a whole, and regardless of their state of derivatization at the time of their formation). In agreement with previous observations, uptake of exogenous choline down-regulates the methylation of phosphoethanolamine, without being accompanied by secondary accumulation of a marked excess of ethanolamine derivatives.findings bring to the fore the question of the biosynthetic origin in higher plants of P-EA, a compound crucial to initiation of each of these metabolic pathways. One route to P-EA, each of the component steps of which has been demonstrated in higher plants, involves the decarboxylation of PtdSerine:PtdSerine --PtdEA + CO2 (reaction 1)PtdSerine decarboxylase activity has been demonstrated in extracts of spinach leaves, chiefly in the 100,000g supernatant fraction (26,27 Plant Physiol. Vol. 91, 1989 10, 18), contribution to EA formation. EA is a widespread constituent of higher plants (23), but a decarboxylase unequivocally acting on free serine (5, 10) has not, to our knowledge, been reported.Once EA is formed, the pathway to P-EA may be completed by EA kinase:This kinase is well known in higher plants (29,30), including Lemna (32,33).An alternative route to P-EA, entirely speculative at the moment (32), would involve the decarboxylation of P-serine:Evidence (reviewed and summarized by Keys [21 ]) is available suggesting that P-serine may be formed in at least some higher plants from the photosynthetic and glycolytic intermediate, P-glycerate, by successive oxidation and transamination.An additional uncertainty related to P-EA metabolism in higher plants is whether this compound can be converted to PtdEA by a sequence analogous to that for the c...

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Section: Introductionmentioning

confidence: 99%

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confidence: 99%

Synthesis of Ethanolamine and Its Regulation in Lemna paucicostata

Mudd¹,

Datko²

1989

Plant Physiol.

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“…The crude homogenate incorporated four times as much "C-CDP-ethanolamine as "C-CDP-choline. Both compounds were incorporated at a rate approximately 100 times slower than has been reported for a spinach microsomal preparation (22).…”

Section: Lipidmentioning

confidence: 87%

“…Bradbeer and Stumpf (6) 4C-CDP-choline and "4C-sn-glycerol 3-phosphate were purchased from International Chemical and Nuclear Corporation (ICN), Irvine, Calif. "C-phosphorylethanolamine was purchased from New England Nuclear, Boston. "4C-CDP-ethanolamine was prepared from "C-phosphorylethanolamine as previously described (22) Incubations were for 30 min at 30 C. At the end of the reaction, 0.2 ml of 80% (w/v) trichloroacetic acid was added, and the extraction of the lipid was performed according to the method of Bligh and Dyer (5). The chloroform layer was washed twice with water and then a 1 ml aliquot was pipetted into a scintillation vial.…”

Section: Lipidmentioning

confidence: 99%

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Studies on Phospholipid-synthesizing Enzyme Activities during the Growth of Etiolated Cucumber Cotyledons

Macher

Brown²,

McManus³

et al. 1975

Plant Physiol.

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The enzymatic incorporation of stn-glycerol 3-phosphate into lipid by extracts of cucumber (Cucumis sativus) cotyledons showed an absolute requirement for ATP (saturation 2 mM). The incorporation was stimulated 4-fold by 0.2 mM oleate. Ethyldiaminetetraacetate stimulated the incorporation at concentrations below 1 mM and inhibited at higher concentrations. Mg2+ did not affect the reaction. Triton X-100 and Cutscum inhibited the reaction, while a third detergent, Span 80, was stimulatory. p-Mercuribenzoate was inhibitory. The enzymatic reaction has a pH optimum in the range of 8.8 to 9.6. The Michaelis constant was 112 ,uM for sn-glycerol 3-phosphate. The major amount of product was phosphatidic acid, the remainder was diacylglycerol, monoacylglycerol, and an unknown phospholipid. We have asked the second question in response to a suggestion put forward by Pieringer et al. (24) in a paper on PA synthesis in E. coli. They have shown that E. coli can synthesize PA by two separate reactions: (a) acylation of sn-glycerol 3-phosphate, and (b) phosphorylation of 1, 2-diacyl-sn-glycerol. The first reaction accounts for de novo synthesis. Pieringer et al. (24) have suggested that the second reaction acts as a scavenger system for glycerides formed from partially degraded phospholipids. Since bacteria must rapidly conform to changing environments (for example via membrane alterations), an enzyme system capable of utilizing partially degraded phospholipids for new phospholipid synthesis would be more efficient than a system using the products from fully degraded phospholipids. In the same manner, plants could benefit by phosphorylating partially degraded triacylglycerols to provide phospholipid precursors during germination. Bradbeer and Stumpf (6) have reported the diglyceride kinase activity in peanut cotyledons. MATERIALS AND METHODS

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Lipidstoffwechsel in pflanzlichen Zellkulturen: Komplexe Etherlipide aus exogenen Alkylglycerinen

Weber¹

1983

Fette, Seifen, Anstrichm.

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Heterotrophe Zellsuspensionskulturen von Soja (Glycine max) und photomixotrophe Zellsuspensionskulturen von Raps (Brassica napus) wurden mit langkettigen Alkoholen inkubiert. Diese Verbindungen wurden zu Wachsestern verestert oder zu Fettsäuren oxidiert. ‐ Photomixotrophe Zellsuspensionskulturen von Raps wurden mit rac‐1‐0‐Alkylglycerinen inkubiert. Diese Verbindungen wurden hauptsächlich zu neutralen und ionischen Etherglycerolipiden verstoffwechselt. Aus dem angebotenen Enantiomerengemisch wurden spezifisch 1‐0‐Alkyl‐sn‐glycerine in komplexe Alkylglycerolipide eingebaut. Auf diese Weise können neutrale und ionische 1‐0‐Alkyl‐2‐0‐acyl‐sn‐glycerolipide mit definiertem Alkyl‐Rest aus racemischen Gemischen von Alkylglycerinen gewonnen werden. Die Methode empfiehlt sich besonders für die Herstellung radioaktiver Alkylacylglycerophospholipide. 1‐0‐Alk‐1'‐enyl‐2‐0‐acyl‐sn‐glycerophospholipide werden von den Rapszellen aus exogenen 1‐0‐Alk‐l'‐enylglycerinen gebildet. Aus 1‐0‐Alkyl‐2‐0‐acyl‐sn‐glycero‐3‐phosphocholinen lassen sich biologisch aktive 1‐0‐Alkyl‐2‐0‐acetyl‐sn‐glycero‐3‐phosphocholine ' platelet activating factor' (PAF), herstellen.

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Biosynthesis of Phosphatidylethanolamine by Enzyme Preparations from Plant Tissues

Cited by 45 publications

References 36 publications

Synthesis of Ethanolamine and Its Regulation in Lemna paucicostata

Synthesis of Ethanolamine and Its Regulation in Lemna paucicostata

Studies on Phospholipid-synthesizing Enzyme Activities during the Growth of Etiolated Cucumber Cotyledons

Lipidstoffwechsel in pflanzlichen Zellkulturen: Komplexe Etherlipide aus exogenen Alkylglycerinen

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