Lipid phosphorylation in chloroplast envelopes. Evidence for galactolipid CTP-dependent kinase activities.
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 [gamma-(32)P]ATP. These two lipids incorporated radioactive phosphate in chloroplasts in the presence of [gamma-(32)P]ATP or [(32)P]P(i) and light. Interestingly, these two lipids were preferentially phosphorylated in envelope membranes in the presence [gamma-(32)P]CTP, as the phosphoryl donor, or [gamma-(32)P]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) (CTPgammaS) 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. CTPgammaS 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.
Müller
M O
MO
Laboratory of Plant Physiology, University of Neuchâtel, 2007 Neuchâtel, Switzerland.
Meylan-Bettex
M
M
Eckstein
F
F
Martinoia
E
E
Siegenthaler
P A
PA
Bovet
L
L
D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism*; D002855:Chromatography, Thin Layer; D003570:Cytidine Triphosphate / Q000378:metabolism*; D004075:Diglycerides / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D038983:Galactolipids; D005690:Galactose / Q000494:pharmacology; D006017:Glycolipids / Q000378:metabolism / Q000494:pharmacology; D006868:Hydrolysis; D007425:Intracellular Membranes / Q000378:metabolism*; D050356:Lipid Metabolism; D010766:Phosphorylation; D010770:Phosphotransferases / Q000378:metabolism*; D018724:Spinacia oleracea / Q000737:chemistry; D013820:Thermolysin / Q000494:pharmacology; D020524:Thylakoids / Q000378:metabolism; D013997:Time Factors
D004075:Diglycerides; D038983:Galactolipids; D006017:Glycolipids; C009909:monogalactosyldiacylglycerol; D003570:Cytidine Triphosphate; D010770:Phosphotransferases; D013820:Thermolysin; D005690:Galactose