scholarly journals Comparison of glycerolipid biosynthesis in non-green plastids from sycamore (Acer pseudoplatanus) cells and cauliflower (Brassica oleracea) buds

1989 ◽  
Vol 259 (3) ◽  
pp. 775-783 ◽  
Author(s):  
C Alban ◽  
J Joyard ◽  
R Douce
Keyword(s):  
Fatty Acids ◽  
Phosphatidic Acid ◽  
Brassica Oleracea ◽  
Phosphatase Activity ◽  
Lysophosphatidic Acid ◽  
Acyl Carrier Protein ◽  
Acer Pseudoplatanus ◽  
Envelope Membrane ◽  
Phosphatidate Phosphatase ◽  
Envelope Membranes

The availability of methods to fractionate non-green plastids and to prepare their limiting envelope membranes [Alban, Joyard & Douce (1988) Plant Physiol. 88, 709-717] allowed a detailed analysis of the biosynthesis of lysophosphatidic acid, phosphatidic acid, diacylglycerol and monogalactosyl-diacylglycerol (MGDG) in two different types of non-green starch-containing plastids: plastids isolated from cauliflower buds and amyloplasts isolated from sycamore cells. An enzyme [acyl-ACP (acyl carrier protein):sn-glycerol 3-phosphate acyltransferase) recovered in the soluble fraction of non-green plastids transfers oleic acid from oleoyl-ACP to the sn-1 position of sn-glycerol 3-phosphate to form lysophosphatidic acid. Then a membrane-bound enzyme (acyl-ACP:monoacyl-sn-glycerol 3-phosphate acyltransferase), localized in the envelope membrane, catalyses the acylation of the available sn-2 position of 1-oleoyl-sn-glycerol 3-phosphate by palmitic acid from palmitoyl-ACP. Therefore both the soluble phase and the envelope membranes are necessary for acylation of sn-glycerol 3-phosphate. The major difference between cauliflower (Brassica oleracea) and sycamore (Acer pseudoplatanus) membranes is the very low level of phosphatidate phosphatase activity in sycamore envelope membrane. Therefore, very little diacylglycerol is available for MGDG synthesis in sycamore, compared with cauliflower. These findings are consistent with the similarities and differences described in lipid metabolism of mature chloroplasts from ‘C18:3’ and ‘C16:3’ plants (those with MGDG containing C18:3 and C16:3 fatty acids). Sycamore contains only C18 fatty acids in MGDG, and the envelope membranes from sycamore amyloplasts have a low phosphatidate phosphatase activity and therefore the enzymes of the Kornberg-Pricer pathway have a low efficiency of incorporation of sn-glycerol 3-phosphate into MGDG. By contrast, cauliflower contains MGDG with C16:3 fatty acid, and the incorporation of sn-glycerol 3-phosphate into MGDG by the enzymes associated with envelope membranes is not limited by the phosphatidate phosphatase. These results demonstrate that: (1) non-green plastids employ the same biosynthetic pathway as that previously established for chloroplasts (the formation of glycerolipids is a general property of all plastids, chloroplasts as well as non-green plastids), (2) the envelope membranes are the major structure responsible for the biosynthesis of phosphatidic acid, diacylglycerol and MGDG, and (3) the enzymes of the envelope Kornberg-Pricer pathway have the same properties in non-green starch-containing plastids as in mature chloroplasts from C16:3 and C18:3 plants.

scholarly journals Characterization of dolichol and dolichyl phosphate phosphatase from soya beans (Glycine max)

1983 ◽  
Vol 213 (2) ◽  
pp. 513-518 ◽  
Author(s):  
K Ravi ◽  
J W Rip ◽  
K K Carroll
Keyword(s):  
Enzyme Activity ◽  
Glycine Max ◽  
Phosphatidic Acid ◽  
Phosphatase Activity ◽  
Lysophosphatidic Acid ◽  
Competitive Inhibition ◽  
High Yield ◽  
Dolichyl Phosphate ◽  
Ability To Act ◽  
Phosphorylated Compounds

A series of polyprenols, ranging in length from 15 to 22 isoprene units, has been isolated from soya beans (Glycine max) and purified by high-pressure liquid chromatography. N.m.r., i.r. and mass spectra of the compounds indicated that they are alpha-saturated polyprenols of the dolichol type. The amount present in dry seeds was about 9 mg/100 g, whereas dolichyl phosphate (Dol-P) was present only in trace amounts. Dol-P phosphatase activity was detected in the microsomal fraction of 5-day-old germinating soya-bean cotyledons. The Dol-P phosphatase activity was linear with respect to time and protein concentration and exhibited a broad pH optimum (pH 7-9). Triton X-100 was necessary for significant enzyme activity. Enzyme activity was slightly enhanced by EDTA, whereas dithiothreitol was without effect. An apparent Km of 5 microM was determined for Dol-P. Bivalent metal ions were not required for enzyme activity. A number of phosphorylated compounds tested as enzyme substrates (including a number of nucleoside phosphates, glucose 6-phosphate, sodium β 1 leads to 4Glc. Because of the ease of purification of the enzyme and high yield in the absence of contaminating glycosidases and proteinases, Bacteroides fragilis is a valuable source of endo-beta-galactosidase for the structural analysis of carbohydrate chains. -glycerophosphate and Na4P2O7) did not compete with [1-3H]Dol-P as substrate. A number of phospholipids were also tested for their ability to act as Dol-P phosphatase substrates. At 1 mM concentration, phosphatidylcholine, phosphatidylethanolamine, phosphatidic acid and lysophosphatidic acid each inhibited enzymic activity. However, at 0.1 mM concentration, phosphatidylcholine and phosphatidylethanolamine were slightly stimulatory, whereas phosphatidic acid and lysophosphatidic acid were still inhibitory. Phosphatidic acid showed competitive inhibition.

scholarly journals Toxoplasma LIPIN is essential in channeling host lipid fluxes through membrane biogenesis and lipid storage

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sheena Dass ◽  
Serena Shunmugam ◽  
Laurence Berry ◽  
Christophe-Sebastien Arnold ◽  
Nicholas J. Katris ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Phosphatidic Acid ◽  
De Novo ◽  
Lipid Synthesis ◽  
Parasite Development ◽  
Membrane Biogenesis ◽  
Membrane Phospholipids ◽  
Phosphatidic Acid Phosphatase ◽  
Intracellular Parasites ◽  
Parasite Survival

AbstractApicomplexa are obligate intracellular parasites responsible for major human diseases. Their intracellular survival relies on intense lipid synthesis, which fuels membrane biogenesis. Parasite lipids are generated as an essential combination of fatty acids scavenged from the host and de novo synthesized within the parasite apicoplast. The molecular and metabolic mechanisms allowing regulation and channeling of these fatty acid fluxes for intracellular parasite survival are currently unknown. Here, we identify an essential phosphatidic acid phosphatase in Toxoplasma gondii, TgLIPIN, as the central metabolic nexus responsible for controlled lipid synthesis sustaining parasite development. Lipidomics reveal that TgLIPIN controls the synthesis of diacylglycerol and levels of phosphatidic acid that regulates the fine balance of lipids between storage and membrane biogenesis. Using fluxomic approaches, we uncover the first parasite host-scavenged lipidome and show that TgLIPIN prevents parasite death by ‘lipotoxicity’ through effective channeling of host-scavenged fatty acids to storage triacylglycerols and membrane phospholipids.

Mechanism of protein import across the chloroplast envelope

2000 ◽  
Vol 28 (4) ◽  
pp. 485-491 ◽  
Author(s):  
K. Chen ◽  
X. Chen ◽  
D. J. Schnell
Keyword(s):  
Protein Import ◽  
Essential Elements ◽  
Chloroplast Envelope ◽  
Envelope Membrane ◽  
Outer Envelope ◽  
Double Membrane ◽  
Protein Subunits ◽  
Targeting Signals ◽  
Outer Envelope Membrane ◽  
Envelope Membranes

The development and maintenance of chloroplasts relies on the contribution of protein subunits from both plastid and nuclear genomes. Most chloroplast proteins are encoded by nuclear genes and are post-translationally imported into the organelle across the double membrane of the chloroplast envelope. Protein import into the chloroplast consists of two essential elements: the specific recognition of the targeting signals (transit sequences) of cytoplasmic preproteins by receptors at the outer envelope membrane and the subsequent translocation of preproteins simultaneously across the double membrane of the envelope. These processes are mediated via the co-ordinate action of protein translocon complexes in the outer (Toe apparatus) and inner (Tic apparatus) envelope membranes.

scholarly journals Channeling of Eukaryotic Diacylglycerol into the Biosynthesis of Plastidial Phosphatidylglycerol

2006 ◽  
Vol 282 (7) ◽  
pp. 4613-4625 ◽  
Author(s):  
Markus Fritz ◽  
Heiko Lokstein ◽  
Dieter Hackenberg ◽  
Ruth Welti ◽  
Mary Roth ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Double Bond ◽  
Transgenic Plants ◽  
Phosphatidic Acid ◽  
Lipid Analysis ◽  
Photosynthetic Apparatus ◽  
Hexadecenoic Acid ◽  
Transgenic Tobacco Plants ◽  
Tobacco Plants

Plastidial glycolipids contain diacylglycerol (DAG) moieties, which are either synthesized in the plastids (prokaryotic lipids) or originate in the extraplastidial compartment (eukaryotic lipids) necessitating their transfer into plastids. In contrast, the only phospholipid in plastids, phosphatidylglycerol (PG), contains exclusively prokaryotic DAG backbones. PG contributes in several ways to the functions of chloroplasts, but it is not known to what extent its prokaryotic nature is required to fulfill these tasks. As a first step toward answering this question, we produced transgenic tobacco plants that contain eukaryotic PG in thylakoids. This was achieved by targeting a bacterial DAG kinase into chloroplasts in which the heterologous enzyme was also incorporated into the envelope fraction. From lipid analysis we conclude that the DAG kinase phosphorylated eukaryotic DAG forming phosphatidic acid, which was converted into PG. This resulted in PG with 2–3 times more eukaryotic than prokaryotic DAG backbones. In the newly formed PG the unique Δ3-trans-double bond, normally confined to 3-trans-hexadecenoic acid, was also found in sn-2-bound cis-unsaturated C18 fatty acids. In addition, a lipidomics technique allowed the characterization of phosphatidic acid, which is assumed to be derived from eukaryotic DAG precursors in the chloroplasts of the transgenic plants. The differences in lipid composition had only minor effects on measured functions of the photosynthetic apparatus, whereas the most obvious phenotype was a significant reduction in growth.

Diacylglycerol Biosynthesis in Everted Sacs of Rat Intestinal Mucosa

1975 ◽  
Vol 53 (11) ◽  
pp. 1170-1183 ◽  
Author(s):  
W. C. Breckenridge ◽  
A. Kuksis
Keyword(s):  
Fatty Acids ◽  
Phosphatidic Acid ◽  
Thin Layer ◽  
Free Fatty Acids ◽  
Thin Layer Chromatography ◽  
Intestinal Mucosa ◽  
Gas Liquid Chromatography ◽  
Acid Pathway ◽  
Layer Chromatography ◽  
Everted Sacs

The molecular specificity in the biosynthesis of diacylglycerols by rat intestinal mucosa was examined by means of radioactive markers, thin-layer chromatography with silver nitrate and gas-liquid chromatography with radioactivity monitoring. Bile salt micelles of alternately labeled monoacylglycerols and free fatty acids were incubated with everted sacs of intestinal mucosa for various periods of time and the diacylglycerols were isolated by solvent extraction and thin-layer chromatography. Stereospecific analyses of the X-1,2-diacylglycerols labeled from 2-monoacylgiycerols showed that the sn-1,2-isomers (45–55%) were slightly in excess of the sn-2,3-isomers (34–45%) with the X-1,3-diacylglycerols accounting for the rest of the radioactivity (5–10%). This suggests that racemic diacylglycerols may be intermediates in the resynthesis of dietary fat in rat intestinal mucosa. Detailed analyses of the molecular species of the sn-1,2-diacylglycerols labeled from free fatty acids revealed that 10–45% of the total did not contain the acid present in the 2-monoacylglycerol supplied, and therefore had originated from the phosphatidic acid pathway. These findings are at variance with those obtained in isolated microsomes, which have suggested an inhibition of the phosphatidic acid pathway by monoacylglycerols as well as have given evidence of an exclusive synthesis of sn-1,2-diacylglycerols from 2-monoacylglycerols.

scholarly journals Σύνθεση και μελέτη αναστολέων λιπολυτικών ενζύμων

2016 ◽  
Author(s):  
Αικατερίνη Νικολάου
Keyword(s):  
Fatty Acids ◽  
Lysophosphatidic Acid ◽  
Inhibitory Activity ◽  
Functional Group ◽  
Inflammatory Diseases ◽  
Hydroxamic Acids ◽  
Pharmacological Properties ◽  
Ester Bond ◽  
Phospholipases A2 ◽  
Inflammatory Conditions

Phospholipases A2 (PLA2) are enzymes that hydrolyze the sn-2 ester bond of phospholipids releasing free fatty acids and lysophospholipids. Among them, arachidonic acid can be converted into a variety of eicosanoids by metabolic enzymes, while lysophosphatidylcholine (LPC), the most abundant lysophospholipid in plasma and tissues, can be converted into lysophosphatidic acid (LPA) by a secreted enzyme that exhibits lysophospholipase D activity, known as autotaxin (ATX). Both enzymes are involved in inflammatory conditions and, as a consequence, constitute attractive targets for the development of novel agents for the treatment of inflammatory diseases. Due to the fact that molecules which bear the 2-oxoamide functional group and long aliphatic chains exhibit inhibitory activity against cytosolic GIVA cPLA2, 2-oxoamideswith reduced lipophilicity were designed and synthesized. Taking into consideration that in recent years hydroxamic acids have attracted considerable attention due to their pharmacological properties, hydroxamic acids and derivatives there of were designed and synthesized, so as to evaluate their inhibitory activity against ATX.

Growth factor-like phospholipids generated after corneal injury

1998 ◽  
Vol 274 (4) ◽  
pp. C1065-C1074 ◽  
Author(s):  
Károly Liliom ◽  
Zhiwei Guan ◽  
Jih-Lie Tseng ◽  
Dominic M. Desiderio ◽  
Gábor Tigyi ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Growth Factor ◽  
Phosphatidic Acid ◽  
Aqueous Humor ◽  
Lysophosphatidic Acid ◽  
Xenopus Oocyte ◽  
Two Dimensional ◽  
Corneal Injury ◽  
Rabbit Eye ◽  
Cellular Regeneration

The present study provides evidence that growth factor-like glycerophosphate mediators of the lysophosphatidic acid (LPA) family are present in the aqueous humor and the lacrimal gland fluid of the rabbit eye. By use of a combination of HPLC, two-dimensional TLC, mass spectrometry, and the Xenopus oocyte bioassay, the LPA-like phospholipids LPA, cyclic PA, alkenyl-glycerophosphate (GP), lysophosphatidylserine, and phosphatidic acid were detected as physiological constituents of the fluids bathing the cornea. Corneal injury resulted in an increased production of some of these mediators. Alkenyl-GP, a novel member of the LPA family, has been identified in postinjury aqueous humor, establishing that it is generated endogenously. LPA and its homologues were found to be mitogenic in freshly dissociated keratocytes from uninjured corneas. There appears to be a link between the occurrence of LPA responsiveness in keratocytes activated by injury and the increase in LPA-like activity in aqueous humor. These data suggest that LPA and its homologues are involved in maintaining the integrity of the normal cornea and in promoting cellular regeneration of the injured cornea.

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