Energy Conservation in Photosynthetic Electron Transport of Chloroplasts

Trebst, Achim

doi:10.1146/annurev.pp.25.060174.002231

Cited by 452 publications

(136 citation statements)

References 158 publications

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“…Ferricyanide operates mainly as an electron acceptor at or very near the electron carrier X (42) and therefore by-passes electron transfer via ferredoxin and ferredoxin-NADP + oxidoreductase. Because of the loss of ferredoxin and partial loss of the oxidoreductase during preparation of the chloroplasts, this latter part of the electron transfer is severely rate limiting (24,44). To compensate for these losses, saturating amounts of both proteins were added to the incubation mixtures with NADP + as electron acceptor.…”

Section: Resultsmentioning

confidence: 99%

A photosystem I mutant in barley (Hordeum vulgare L.)

Møller

Smillie

Høyer‐Hansen

1980

Carlsberg Res. Commun.

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The nuclear gene mutant viridis-n 34 in barley has been characterized as a photosystem I mutant. The slow component of the light dependent absorption change at 518 nm and the photooxidation of cytochrome f were greatly reduced in mutant leaves compared with wild-type leaves. The oxidation of cytochrome f in mutant leaves irradiated with far-red light was only 7 % of the value obtained with wild-type. The fast component of the 518 nm absorbance change was similar in wild-type and mutant leaves. The rate of photosystem I electron transport in the mutant is approximately 10% of the rate observed with wild-type thylakoids whereas photosystem II electron transport appears normal. Little or no P700 was detected in the mutant. The levels of cytochromes and ferredoxin-NADP § oxidoreductase were normal. Mutant thylakoids were unable to generate a proton gradient upon illumination. Analysis of the polypeptide composition of thylakoids of viridis-n 34 revealed that these are depleted in chlorophyll a-protein 1 and three polypeptides believed to be iron-sulfur proteins. These four polypeptides are components of photosystem I particles isolated from wild-type barley.Abbreviations: Asc = ascorbic acid, Chl = chlorophyll, Cyt = cytochrome, DBMIB = dibromothymoquinone, DCIP = 2,6-dichlorophenolindophenol, DCMU = 3-(3,4-dichlorophenyl)--l,l-dimethylurea, DTT = dithiothreitol, FeCN = potassium ferricyanide, GD --Gramicidin D, MeV = methylviologen, NADP § = {~-nicotinamide adenine dinucleotide phosphate, PD --p-phenylenediamine, PS = photosystem, SDS-PAGE --sodium dodecyl sulfate polyacrylamide gel electrophoresis, TMPD = N,N,N',N'-tetramethylphenylenediamine, Tricine --N-(tris-(hydroxymethyl)-methyl)glycine, Tris = tris-(hydroxymethyl)aminomethane.

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Section: Resultsmentioning

confidence: 99%

A photosystem I mutant in barley (Hordeum vulgare L.)

Møller

Smillie

Høyer‐Hansen

1980

Carlsberg Res. Commun.

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“…This is usually considered to be the result of the vectorial arrangement of the electron transport chain in the thylakoid membrane [1,2]. Although the chemiosmotic theory as applied to chloroplasts has received a substantial amount of experimental support there still remain questions about the number of protons transported per turnover of the electron transport chain, and about the relationship between the rates of proton exchanges and the rates of the electron transfer reactions assumed to be involved in the proton translocation [3 -81.…”

mentioning

confidence: 99%

Light‐Induced Proton Transport by Chloroplasts Suspended in Fluid Media at Sub‐Zero Temperatures: Kinetics and Stoichiometry

Olsen¹,

Cox²

1979

European Journal of Biochemistry

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Chloroplasts suspended in a medium containing ethanediol and water (1:1, v/v) at –16°C show light‐induced proton uptake and subsequent dark efflux. Proton uptake in continuous light showed biphasic kinetics. A 1 ms flash caused a single turnover of the photochemical centres at –16 °C. Under the same conditions 3 H+ were taken up from the external medium in the presence of methyl viologen as electron acceptor. The flash‐induced proton uptake was exponential and monophasic with t1/2= 3 s. The flash‐induced proton release into the thylakoid interior was biphasic, with half‐times of less than 0.1 s and 3 s. The fast phase represented approximately 30% of the total release and may be correlated with the oxidation of water. The half‐time of reduction of cytochrome f in the dark following illumination in the presence of 2 mM NH4Cl (2.5 s) is similar to the half‐time of the slow phase of proton release, suggesting a correlation between the kinetics of cytochrome f reduction and plastoquinol oxidation.

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“…Mol wt may be misleading in the urea gradient (0-6 M); however, the 20 kD proteins could be analogous to subunit IV (21 kD) of PSI particles as isolated by Bengis and Nelson (2). There was no evidence of the previously described 30 (22). Donation is believed to be to PC (30) located in the soluble matrix on the interior of the thylakoid membrane (16).…”

Section: Discussionmentioning

confidence: 85%

“…Analysis of electron transport activity revealed that the oxidizing side of PSI as the major site of difference. Examination of the whole thylakoids and subchloroplast particle protein components of the common hexaploid and the decaploid genotypes had major polypeptide differences at 30,21, and 12.5 kilodaltons. These differences could not be assigned to a specific physiological function in PSI.…”

mentioning

confidence: 95%