Lipid Phosphorylation in Chloroplast Envelopes

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 [γ-32P]AT...

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Bibliographic Details
Published in:The Journal of biological chemistry 2000-06, Vol.275 (26), p.19475-19481
Main Authors: Müller, Marc-Olivier, Meylan-Bettex, Marlyse, Eckstein, Fritz, Martinoia, Enrico, Siegenthaler, Paul-André, Bovet, Lucien
Format: Article
Language:English
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Summary: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 [γ-32P]ATP. These two lipids incorporated radioactive phosphate in chloroplasts in the presence of [γ-32P]ATP or [32P]Pi and light. Interestingly, these two lipids were preferentially phosphorylated in envelope membranes in the presence [γ-32P]CTP, as the phosphoryl donor, or [γ-32P]ATP, when supplemented with CDP and nucleoside diphosphate kinase II. The lipid kinase activity involved in this reaction was specifically inhibited in the presence of cytosine 5′-O-(thiotriphosphate) (CTPγS) 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. CTPγS 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.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M002575200