Chemiosmotic ATP synthesis in photosynthetically inactive chromoplasts from Narcissus pseudonarcissus L. linked to a redox pathway potentially also involved in carotene desaturation.
Mature chromoplasts from daffodil (Narcissus pseudonarcissus) flowers, although devoid of thylakoid structures, contain immunologically detectable alpha-subunits of ATP-synthase (H(+)-transporting ATP phosphohydrolase; EC 3.6.3.14). To show the presence of the entire functional protein complex, chromoplast membrane proteins were solubilized and reconstituted in phosphatidylcholine liposomes. The membranes were energized by an acid-base transition in the presence of a K(+)/valinomycin diffusion potential, and the initial rate of ATP synthesis was measured with a luciferin/luciferase assay. In addition, by demonstrating NADPH-dependent ATP synthesis, we show that an NAD(P)H-dependent respiratory redox pathway in chromoplasts, previously identified as an important constituent of the carotene desaturation system, proceeds concomitant with membrane energization.
Morstadt
Lucia
L
Zentrum für Angewandte Biowissenschaften, Universität Freiburg, Schänzlestrasse 1, 79104 Freiburg, Germany.
Gräber
Peter
P
De Pascalis
Luca
L
Kleinig
Hans
H
Speth
Volker
V
Beyer
Peter
P
D000255:Adenosine Triphosphate / Q000096:biosynthesis*; D000643:Ammonium Chloride / Q000494:pharmacology; D002338:Carotenoids / Q000378:metabolism*; D004140:Dinitrophenols / Q000494:pharmacology; D015226:Dinucleoside Phosphates / Q000494:pharmacology; D019684:Magnoliopsida / Q000187:drug effects / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D008854:Microscopy, Electron; D009249:NADP / Q000378:metabolism; D009997:Osmotic Pressure; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D010788:Photosynthesis / Q000502:physiology; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism*; D018087:Plastids / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D006180:Proton-Translocating ATPases / Q000378:metabolism
D004140:Dinitrophenols; D015226:Dinucleoside Phosphates; D008565:Membrane Proteins; D045322:Photosynthetic Reaction Center Complex Proteins; D000643:Ammonium Chloride; D002338:Carotenoids; C012275:P(1),P(5)-di(adenosine-5'-)pentaphosphate; D009249:NADP; D000255:Adenosine Triphosphate; D006180:Proton-Translocating ATPases