Molecular mechanisms behind light-induced inhibition of photosystem II electron transport and degradation of reaction centre polypeptides

1. Photosynthetic electron transport from water to lipophilic Photosystem II acceptors was stimulated 3-5-fold by high concentrations (greater than or equal to 1 M) of salts containing anions such as citrate, succinate and phosphate that are high in the Hofmeister series. 2. In trypsin-treated chloroplasts, K3Fe(CN)6 reduction insensitive to 3-(3,4-dichlorophenyl)-1,1-dimethylurea was strongly stimulated by high concentrations of potassium citrate, but there was much less stimulation of 2,6-dichloroindophenol reduction in Tris-treated chloroplasts supplied with 1,5-diphenylcarbazide as artificial donor. The results suggest that the main site of action of citrate was the O2-evolving complex of Photosystem II. 3. Photosystem I partial reactions were also stimulated by intermediate concentrations of citrate (up to 2-fold stimulation by 0.6-0.8 M-citrate), but were inhibited at the highest concentrations. The observed stimulation may have been caused by stabilizaton of plastocyanin that was complexed with the Photosystem I reaction centre, 4. At 1 M, potassium citrate protected O2 evolution against denaturation by heat or by the chaotropic agent NaNO3. 5. It is suggested that anions high in the Hofmeister series stimulated and stabilized electron transport by enhancing water structure around the protein complexes in the thylakoid membrane.

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Electron-transport properties of the isolated D1-D2-cytochrome b-559 Photosystem II reaction centre

Biochimica et Biophysica Acta (BBA) - Bioenergetics ◽

10.1016/0005-2728(88)90077-1 ◽

1988 ◽

Vol 933 (3) ◽

pp. 423-431 ◽

Cited By ~ 111

Author(s):

D.J. Chapman ◽

K. Gounaris ◽

J. Barber

Keyword(s):

Electron Transport ◽

Photosystem Ii ◽

Transport Properties ◽

Cytochrome B ◽

Reaction Centre ◽

Electron Transport Properties

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Photosynthetic components and activities of nitrogen-fixing isolated heterocysts of Anabaena cylindrica

Proceedings of the Royal Society of London Series B Biological Sciences ◽

10.1098/rspb.1977.0086 ◽

1977 ◽

Vol 198 (1130) ◽

pp. 61-86 ◽

Cited By ~ 51

Keyword(s):

Electron Transport ◽

Photosystem Ii ◽

Cytochrome B ◽

Nitrogenase Activity ◽

Photosynthetic Electron Transport ◽

Central Component ◽

Reaction Centre ◽

Anabaena Cylindrica ◽

Higher Plant ◽

Transport Chain

Isolated heterocysts of the N 2 -fixing Anabaena cylindrica , prepared by a combination of lysozyme and Yeda press treatments, are metabolically active with over 90% of the measurable nitrogenase activity being located in the heterocyst preparations after disruption of the intact filaments. The photosynthetic activities of such isolated heterocysts are characterized by an inability to carry out the photolysis of water or to fix CO 2 . The lack of O 2 evolution appears to be due in part to the depletion during heterocyst differentiation of Mn, a central component of the photosystem II reaction centre in O 2 -evolving algae. There is evidence that components of the photosynthetic electron transport chain on the reducing side of the photosystem II reaction centre are present and functional in heterocysts. These include cytochrome c 554 , plastocyanin, plastoquinone, cytochrome b 559 , P700, cytochrome b 563 , and iron-sulphur proteins which appear to correspond to centre A and centre B of higher plant chloroplasts. Soluble, or loosely bound ferredoxin is also present and involved in electron transport from ferredoxin to NADP. Isolated heterocysts photoreduce methylviologen when reduced 2,6-dichlorophenolindophenol and diphenylcarbazide serve as electron donors. They show P700 photo-oxidation and photoreduction, photosynthetic electron transport which is inhibited by 2,5-dibromo-3-methyl-6-isopropyl- p -benzoquinone an antagonist of plastoquinone, photophosphorylation, oxidative phosphorylation and ferredoxin-NADP oxido-reductase mediated reactions. The photosynthetic modifications of the heterocyst are such that electron transport and the generation of ATP for nitrogenase can occur without concomitant O 2 evolution and without nitrogenase having to compete with CO 2 fixation for ATP and reductant.

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Blue Light-Enhanced Photosynthetic Oxygen Evolution from Liposome-Bound Photosystem II Particles; Possible Role of the Xanthophyll Cycle in the Regulation of Cyclic Electron Flow Around Photosystem II?

Zeitschrift für Naturforschung C ◽

10.1515/znc-1995-1-210 ◽

1995 ◽

Vol 50 (1-2) ◽

pp. 61-68 ◽

Cited By ~ 6

Author(s):

W. I. Gruszecki ◽

K. Strzałka ◽

A. Radunz ◽

J. Kruk ◽

G. H. Schmid

Keyword(s):

Electron Transport ◽

Photosystem Ii ◽

Oxygen Evolution ◽

Xanthophyll Cycle ◽

Red Light ◽

Photosynthetic Oxygen Evolution ◽

Reaction Centre ◽

Ps Ii ◽

Photosynthetic Oxygen ◽

Β Carotene

Abstract Light-driven electron transport in liposome-bound photosystem II (PS-II) particles between water and ferricyanide was monitored by bare platinum electrode oxymetry. The modification of the experimental system with the exogenous quinones α-tocopherol quinone ( α-TQ) or plastoquinone (PQ) resulted in a pronounced effect on photosynthetic oxygen evolution. The presence of α-tocopherolquinone ( α-TQ) in PS-II samples decreased the rate of red light-induced oxygen evolution but increased the rate of green light-induced oxygen evolution. Blue light applied to the assay system in which oxygen evolution was saturated by red light resulted in a further increase of the oxygen signal. These findings are interpreted in terms of a cyclic electron transport around PS-II, regulated by an excitation state of β-carotene in the reaction centre of PS-II. A mechanism is postulated according to which energetic coupling of β-carotene in the reaction centre of PS-II and that of other antenna carotenoid pigments is regulated by the portion of the xanthophyll violaxanthin, which is under control of the xanthophyll cycle.

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Photoinhibition Causes Loss of Photochemical Activity Without Degradation of D1 Protein

Functional Plant Biology ◽

10.1071/pp9900641 ◽

1990 ◽

Vol 17 (6) ◽

pp. 641 ◽

Cited By ~ 13

Author(s):

RE Cleland ◽

RT Ramage ◽

C Critchley

Keyword(s):

Electron Transport ◽

Photosystem Ii ◽

Oxygen Evolution ◽

Charge Separation ◽

Photosynthetic Activity ◽

D1 Protein ◽

Photochemical Activity ◽

Reaction Centre ◽

Primary Charge Separation ◽

Primary Damage

Illumination of isolated thylakoids or intact leaves with excess light resulted in a decline in photosynthetic activity measured as primary charge separation in photosystem II (ΔA320), photosystem II- dependent electron transport, or leaf oxygen evolution. It is concluded that the primary damage causing photoinhibition involves inactivation of the reaction centre function, and that degradation of Dl may be a consequence of that event.

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Photosystem II Inhibition by Pyran-enamine Derivatives

Zeitschrift für Naturforschung C ◽

10.1515/znc-1993-3-409 ◽

1993 ◽

Vol 48 (3-4) ◽

pp. 163-167

Author(s):

Koichi Yoneyama ◽

Yoshihiro Nakajima ◽

Masaru Ogasawara ◽

Hitoshi Kuramochi ◽

Makoto Konnai ◽

...

Keyword(s):

Electron Transport ◽

Photosystem Ii ◽

Thylakoid Membranes ◽

Major Determinant ◽

Ps Ii ◽

Structure Activity Relationships ◽

Structure Activity

Abstract Through the studies on structure-activity relationships of 5-acyl-3-(1-aminoalkylidene)-4-hydroxy-2 H-pyran-2,6(3 H)-dione derivatives in photosystem II (PS II) inhibition, overall lipophilicity of the molecule was found to be a major determinant for the activity. In the substituted N -benzyl derivatives, not only the lipophilicity but also the electronic and steric characters of the substituents greatly affected the activity. Their mode of PS II inhibition seemed to be similar to that of DCMU , whereas pyran-enamine derivatives needed to be highly lipophilic to block the electron transport in thylakoid membranes, which in turn diminished the permeability through biomembranes.

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Interaction of Photosystem II Herbicides with Bicarbonate and Formate in Their Effects on Photosynthetic Electron Flow

Zeitschrift für Naturforschung C ◽

10.1515/znc-1984-0512 ◽

1984 ◽

Vol 39 (5) ◽

pp. 374-377 ◽

Cited By ~ 2

Author(s):

J. J. S. van Rensen

Keyword(s):

Electron Transport ◽

Photosystem Ii ◽

Electron Flow ◽

Photosynthetic Electron Transport ◽

Hill Reaction ◽

Amaranthus Hybridus ◽

Apparent Affinity ◽

Photosynthetic Electron Flow ◽

Different Characteristics ◽

The Hill

The reactivation of the Hill reaction in CO2-depleted broken chloroplasts by various concentrations of bicarbonate was measured in the absence and in the presence of photosystem II herbicides. It appears that these herbicides decrease the apparent affinity of the thylakoid membrane for bicarbonate. Different characteristics of bicarbonate binding were observed in chloroplasts of triazine-resistant Amaranthus hybridus compared to the triazine-sensitive biotype. It is concluded that photosystem II herbicides, bicarbonate and formate interact with each other in their binding to the Qв-protein and their interference with photosynthetic electron transport.

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Photoinhibition of Electron Transport Activity of Photosystem II in Isolated Thylakoids Studied by Thermoluminescence and Delayed Luminescence

Zeitschrift für Naturforschung C ◽

10.1515/znc-1988-11-1213 ◽

1988 ◽

Vol 43 (11-12) ◽

pp. 871-876 ◽

Cited By ~ 35

Author(s):

Imre Vass ◽

Narendranath Mohanty ◽

Sándor Demeter

Keyword(s):

Electron Transport ◽

Photosystem Ii ◽

Photosystem I ◽

Half Life ◽

Delayed Luminescence ◽

Transport Activity ◽

Primary Target ◽

Electron Transport Activity ◽

The Stability ◽

Spinach Thylakoids

Abstract The effect of photoinhibition on the primary (QA) and secondary (QB) quinone acceptors of photosystem I I was investigated in isolated spinach thylakoids by the methods of thermoluminescence and delayed luminescence. The amplitudes of the Q (at about 2 °C) and B (at about 30 °C) thermoluminescence bands which are associated with the recombination of the S2QA- and S2QB charge pairs, respectively, exhibited parallel decay courses during photoinhibitory treatment. Similarly, the amplitudes of the flash-induced delayed luminescence components ascribed to the recombination of S20A and S2OB charge pairs and having half life-times of about 3 s and 30 s, respectively, declined in parallel with the amplitudes of the corresponding Q and B thermoluminescence bands. The course of inhibition of thermoluminescence and delayed luminescence intensity was parallel with that of the rate of oxygen evolution. The peak positions of the B and Q thermoluminescence bands as well as the half life-times of the corresponding delayed luminescence components were not affected by photoinhibition. These results indicate that in isolated thylakoids neither the amount nor the stability of the reduced OB acceptor is preferentially decreased by photoinhibition. We conclude that either the primary target of photodamage is located before the O b binding site in the reaction center of photosystem II or QA and OB undergo simultaneous damage.

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