Evidence for lipid kinase activities in spinach chloroplast envelope membranes

Siegenthaler, Paul‐André; Müller, Marc-Olivier; Bovet, Lucien

doi:10.1016/s0014-5793(97)01168-x

Cited by 13 publications

(9 citation statements)

References 24 publications

(25 reference statements)

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“…In a first report we have demonstrated the presence of four phosphorylated lipids in chloroplast envelope membranes, namely PA, LPA, PIP, and LPIP (2). In the present contribution, we show that two additional lipids (X and Y) undergo phosphate incorporation in envelope membranes when carrierfree [␥-…”

Section: Discussionmentioning

confidence: 62%

“…The lipids were visualized under UV light after spraying a solution of acetone/water (60:40) containing 0.01% primuline (w/v). The 32 P-labeled lipids were detected using Kodak X-Omat AR films (2) Synthesis and Purification of CTP␥S-The compound was synthesized enzymatically following the method outlined previously (27). The reaction was carried out in 20 mM Tris-HCl buffer (pH 8.0) and 0.5 mM MgCl 2 (10 ml, total volume) with 50 mg of CDP (from Sigma), 25 mg of ATP␥S (from Fluka) and 500 units of nucleoside diphosphate kinase from yeast (Sigma) at 20°C for 3.5 h. The reaction mixture was dried on a rotary evaporator and the residue dissolved in 2 ml of water.…”

Section: Methodsmentioning

confidence: 99%

“…The solution was subjected to a second preparative HPLC purification, where the major peak was collected. Analytical HPLC showed a major peak at 9.12 min (CTP␥S) and a minor one (13%) of (CTP␥S) 2 Chloroplast Protein Import-35 S-Met-labeled pSSu was synthesized from pSSu/pET8c using the TNT quick coupled transcription/translation system (Promega). Chloroplasts were isolated from spinach leaves and used for the import of the labeled translation products under standard conditions (29).…”

Section: Methodsmentioning

confidence: 99%

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Lipid Phosphorylation in Chloroplast Envelopes

Müller¹,

Meylan-Bettex²,

Eckstein³

et al. 2000

Journal of Biological Chemistry

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Lipid phosphorylation takes place within the chloroplast envelope. In addition to phosphatidic acid, phosphatidylinositol phosphate, and their corresponding lyso-derivatives, we found that two novel lipids underwent phosphorylation in envelopes, particularly in the presence of carrier-free [ The lipid kinase activity involved in this reaction was specifically inhibited in the presence of cytosine 5-O-(thiotriphosphate) (CTP␥S) and sensitive to CTP chase, thereby showing that both lipids are phosphorylated by an envelope CTP-dependent lipid kinase. The lipids were identified as phosphorylated galactolipids by using an acid hydrolysis procedure that generated galactose 6-phosphate. CTP␥S did not affect the import of the small ribulose-bisphosphate carboxylase/oxygenase subunit into chloroplasts, the possible physiological role of this novel CTP-dependent galactolipid kinase activity in the chloroplast envelope is discussed.One of the main functions assigned to the chloroplast is its ability to assimilate CO 2 under illumination. This key activity must be separated from the rest of the cell by a selective membrane barrier, namely the envelope, which is one of the three main plastid compartments in addition to thylakoids and the stroma. The envelope is constituted of two membranes, the inner and the outer envelopes, each having its own specific characteristic and property (1).Lipid phosphorylation occurs in chloroplast envelope membranes (2). The first identified lipids incorporating phosphate from [␥-32 P]ATP in isolated envelope vesicles were lysophosphatidic acid (LPA), 1 phosphatidic acid (PA), phosphatidylinositol phosphate (PIP), and lysophosphatidylinositol phosphate (LPIP). At the present time, the functions of these phospholipids are not known in chloroplasts, but: (i) they might produce substrates for lipid biosynthesis pathways; for instance, PIP can serve as substrate for a phosphatidylinositol-4,5-phosphate kinase and eventually can be hydrolyzed in second messengers like inositol 1,4,5-trisphosphate and DAG (3); (ii) they could directly interact with intracellular proteins to affect their location and/or activity; (iii) they might also change the local topology of other lipids, thereby modifying electrostatic interactions of membrane components. Indeed, in mammalian systems, LPA and PA, as minor cell lipids, are likely to act as potent activators of plasma membrane tyrosine kinase via G protein activation and intracellular protein kinases (4, 5). PA is the product of sn-diacylglycerol phosphorylation catalyzed by a diacylglycerol kinase (6). In plant signaling pathways, PA is also derived from PC via phospholipase D (7) and from diacylglycerol pyrophosphate (8). The production of LPA usually occurs after a first rapid accumulation of DAG, followed by phosphorylation, and activation of a PA-specific phospholipase A 2 within the plasma membrane (9). In plants, a diacylglycerol kinase from Arabidopsis thaliana (10) and LPA, a product of inducible PLA 2 (11), have been identified, but their specific role a...

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Section: Discussionmentioning

confidence: 62%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Lipid Phosphorylation in Chloroplast Envelopes

Müller¹,

Meylan-Bettex²,

Eckstein³

et al. 2000

Journal of Biological Chemistry

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“…DAG, which is a transient compound found in the cell, exists in plants as a wide range of molecular species (8), thereby rendering difficult the study of DAG kinase(s) substrate specificity and its cell location. The presence of a DGK activity associated with chloroplast envelope membranes was first described in (2). In addition, DAG was reported to be the main hydrolysis product appearing during the preparation of envelope membranes (9).…”

mentioning

confidence: 96%

“…Indeed, chloroplasts, mitochondria, the endoplasmic reticulum, glyoxysomes and other vesicular membranes are all putative sites for lipid phosphorylation. Concerning the chloroplast, lipid phosphorylation occurs in envelope membranes, but not in thylakoid membranes, and galactolipids are substrates for CTP-dependent kinase(s) (2,3).…”

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confidence: 99%