title: Effect of monogalactosyldiacylglycerol and other thylakoid lipids on violaxanthin de-epoxidation in liposomes.
abstract: In this study we present evidence that one of two reactions of the xanthophyll cycle, violaxanthin de-epoxidation, may occur in unilamellar egg phosphatidylcholine vesicles supplemented with monogalactosyldiacylglycerol (MGDG). Activity of violaxanthin de-epoxidase (VDE) in this system was found to be strongly dependent on the content of MGDG in the membrane; however, only to a level of 30 mol%. Above this concentration the rate of violaxanthin de-epoxidation decreased. The effect of individual thylakoid lipids on VDE-independent violaxanthin transformation was also investigated and unspecific effects of phosphatidylglycerol and sulphoquinovosyldiacyglycerol, probably related to the acidic character of these lipids, were found. The presented results suggest that violaxanthin de-epoxidation most probably takes place inside MGDG-rich domains of the thylakoid membrane. The described activity of the violaxanthin de-epoxidation reaction in liposomes opens new possibilities in the investigation of the xanthophyll cycle and may contribute to a better understanding of this process.
authors.affiliation: Department of Plant Physiology and Biochemistry, The Jan Zurzycki Institute of Molecular Biology, Jagiellonian University, Al. Mickiewicza 3, 31-120 Kraków, Poland.
authors.forename: D
authors.initials: D
authors.lastname: Latowski
authors.forename: A
authors.initials: A
authors.lastname: Kostecka
authors.forename: K
authors.initials: K
authors.lastname: Strzałka
mesh_terms: D004075:Diglycerides / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D038983:Galactolipids; D006017:Glycolipids / Q000494:pharmacology*; D007700:Kinetics; D008081:Liposomes; D014975:Lutein / Q000378:metabolism; D000455:Medicago sativa; D010088:Oxidoreductases / Q000187:drug effects / Q000378:metabolism*; D010713:Phosphatidylcholines; D018515:Plant Leaves / Q000201:enzymology; D020524:Thylakoids / Q000378:metabolism*; D014908:Triticum / Q000201:enzymology*; D024341:Xanthophylls; D019207:beta Carotene / Q000031:analogs & derivatives* / Q000378:metabolism*
chemical_list: D004075:Diglycerides; D004791:Enzyme Inhibitors; D038983:Galactolipids; D006017:Glycolipids; D008081:Liposomes; D010713:Phosphatidylcholines; D024341:Xanthophylls; C007388:digalactosyldiacylglycerol; C009909:monogalactosyldiacylglycerol; C013694:sulfoquinovosyl diglyceride; D019207:beta Carotene; C005613:violaxanthin; D010088:Oxidoreductases; C023290:violaxanthin de-epoxidase; D014975:Lutein