Energy‐regulated Functional Transitions of Chloroplast Atpase

Schuurmans, Jaap; Kraayenhof, Ruud

doi:10.1111/j.1751-1097.1983.tb04438.x

Cited by 7 publications

(1 citation statement)

References 35 publications

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“…The membrane-bound ATPase complex, exclusively located in the exposed thylakoid domains, can be activated for ATP hydrolysis by light in the presence of DTE, and its activity remains under control of the membrane-energized state induced by ATP hydrolysis (1,24). Figure IC shows that this reaction also shows a discontinuity (at about 16°C), whereas the uncoupler-stimulated reaction does not.…”

Section: Methodsmentioning

confidence: 93%

Temperature Dependence of Energy-Transducing Functions and Inhibitor Sensitivity in Chloroplasts

Schuurmans¹,

Veerman²,

Francke³

et al. 1984

Plant Physiol.

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A comparative analysis of the temperature dependence of energytransducing reactions in spinach (Spinacia oklwea) chloroplasts and their sensitivity for uncouplers and energy-transfer inhibitors at different temperatures is presented. Arrhenius plots reveal two groups of transitions, around 19°C and around 12C. Activities that show transitions around 19°C include linear electron flow from water to ferricyanide, its coupled photophosphorylation, the dark-release of the fluorescent probe atebrin, and the slow component of the 515 nm (carotenoid) absorbance decay after a flash. The transitions around 12°C are observed with pyocyanine-mediated cyclic photophosphorylation, light-and dithioerythritol-activated ATP hydrolysis, the dark-release of protons, and the fast 515 nm decay component. It is suggested that both groups of temperture trnsitions are determined by proton displacements in different domains of the exposed thylakoid membranes. The effects of various uncouplers and an energy-transfer inhibitor are temperature dependent. Some uncouplers also show a different relative inhibition of proton uptake and ATP synthesis at lower temperatures. The efficiency of energy transduction (ATP/e2) varied with temperature and was optimal around 10°C.The investigation ofthe temperature dependence ofthe partial reactions involved in photosynthetic energy transduction is important from both applied and fundamental viewpoints. The flexibility of plant species in their adaptation to different environmental temperatures may be limited by a single partial process. Discontinuities in the rates of electron transfer and energytransducing reactions as functions of temperature have been correlated with growth temperature (5,14,20), their relative sensitivity to environmental temperatures (16,20), and acclimatization (20). More recently, Nolan and Smillie (17) and Nolan (18,19) argued that such discontinuities, although characteristic for different plant species, are not necessarily correlated with chilling-sensitivity. From these and many other studies (2-5, 7, 11, 1-7-19, 27-30) (thylakoid) membrane lipid-protein structures, not necessarily by specific lipid phase transitions.Such studies are also of fundamental significance since they contribute to further resolution of sequential and parallel energytransducing events. Much information is available on temperature dependence of partial energy-transducing reactions such as photophosphorylation (7, 12, 13), proton translocation (7,19,27,30), delayed light emission (6), redox reactions of Cyt b-559 (12, 29), the electric potential-indicating carotenoid absorbance change at 515 nm (3,14,28), and the responses of paramagnetic probes (2, 16) and the fluorescent 'energy probe' atebrin and other aminoacridines (7; see also 8, 9). Torres-Pereira et al. (26) have correlated a light-induced decrease of dielectric constant with an increased protein clustering in thylakoid membranes. All of these partial reactions show discontinuities in the Arrhenius plots. In spinach thylakoid membranes...

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Section: Methodsmentioning

confidence: 93%