Effects of inorganic phosphate on the light dependent thylakoid energization of intact spinach chloroplasts

Journal Article · Fri Sep 01 00:00:00 EDT 1989 · Plant Physiology; (USA)

DOI:https://doi.org/10.1104/pp.91.1.221· OSTI ID:5857924

Heineke, D; Heldt, H W ^[1]; Stitt, M ^[2]

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1. Universitaet Goettingen (West Germany)
2. Universitaet Bayreuth (West Germany)

The light dependent energization of the thylakoid membrane was analyzed in isolated intact spinach (Spinacia oleracea L.) chloroplasts incubated with different concentrations of inorganic phosphate (Pi). Two independent methods were used: (a) the accumulation of ({sup 14}C)5,5-dimethyl-2,4-oxazolidinedione and ({sup 14}C)methylamine; (b) the energy dependent chlorophyll fluorescence quenching. The inhibition of CO{sub 2} fixation by superoptimal medium Pi or by adding glyceraldehyde - an inhibitor of the Calvin cycle - leads to an increased energization of the thylakoid membrane; however, the membrane energization decreases when chloroplasts are inhibited by suboptimal Pi. This specific low phosphate effect could be partially reversed by adding oxaloacetate, which regenerates the electron acceptor NADP{sup +} and stimulates linear electron transport. The energization seen in low Pi is, however, always lower than in superoptimal Pi, even in the presence of oxaloacetate. Energization recovers in the presence of low amounts of N,N{prime}-dicyclohexylcarbodiimide, which reacts with proton channels including the coupling factor 1 ATP synthase. N,N{prime}-Dicyclohexylcarbodiimide has no effect on energization of chloroplasts in superoptimal Pi. These results suggest there is a specific low phosphate proton leak in the thylakoids, and its origin is discussed.

• OSTI ID: 5857924
• Journal Information: Plant Physiology; (USA), Vol. 91:1; ISSN 0032-0889
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
PHOSPHATES
BIOLOGICAL EFFECTS
CARBON 14 COMPOUNDS
PHOSPHORUS
SPINACH
THYLAKOID MEMBRANE PROTEINS
TRACER TECHNIQUES
ELEMENTS
FOOD
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MAGNOLIOPHYTA
MAGNOLIOPSIDA
MEMBRANE PROTEINS
NONMETALS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PHOSPHORUS COMPOUNDS
PLANTS
PROTEINS
VEGETABLES
550201* - Biochemistry- Tracer Techniques