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 α-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.