Effects of chloride depletion on electron donation from the water-oxidizing complex to the photosystem II reaction center as measured by the microsecond rise of chlorophyll fluorescence in isolated pea chloroplasts

Itoh, Shigeru; Yerkes, Christine T.; Koike, Hiroyuki; Robinson, Howard; Crofts, Antony R.

doi:10.1016/0005-2728(84)90122-1

Cited by 98 publications

(72 citation statements)

References 31 publications

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“…The persisting P680+ has been reported to act as a fluorescence quencher (18), which may explain the lowering of Fm observed under photoinhibitory conditions. High light-induced changes in the photosynthetic apparatus have been divided into two categories, reversible and irreversible (2).…”

Section: In Vivo Chi Fluorescencementioning

confidence: 98%

Function of Photosynthetic Apparatus of Intact Wheat Leaves under High Light and Heat Stress and Its Relationship with Peroxidation of Thylakoid Lipids

Mishra¹,

Singhal²

1992

Plant Physiol.

147

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Effects of high light and temperature stress on the structure and function of the photosynthetic apparatus of wheat (Triticum aestivum) were studied. There was a decrease in the electron transport activity of chloroplasts isolated from photoinhibited and heat-stressed leaves. Chlorophyll fluorescence was measured in photoinhibited and heat-stressed leaves and the decrease in variable fluorescence and variable to maximum fluorescence ratio of the stressed leaves indicated a loss in the quantum yield of photosynthesis. The decrease in electron transport activity was accompanied by an increase in peroxidation of thylakoid lipids. Lipid peroxidation indicated the oxidative degradation of polyunsaturated fatty acyl residues of the thylakoid lipids. A negative correlation was observed between electron transport activity and lipid peroxidation. The electron transport activity was completely lost as the peroxidation level reached a threshold equivalent to 0.6 micromoles malondialdehyde. The threshold of lipid peroxidation for complete loss of activity was the same for both photoinhibition and heat treatment, suggesting that the nature of the environmental stress may be less important with respect to the relationship between electron transport and lipid peroxidation. Thus, it seems likely that lipids are required for sustaining the photosynthetic activity under environmental stress, and a loss in activity is observed as the lipids are degraded either by high light or high temperature stress.The photosynthetic activity of an organism can be severely reduced after exposure to light intensity in excess of that required to saturate photosynthesis. This phenomenon, referred to as photoinhibition (14,19,23) atoms of the oxygen-evolving complex (22, 27), denaturation of certain functional proteins (27), and the lateral phaseseparation of the nonbilayer-forming galactolipid monogalactosyldiacylglycerol of thylakoid membranes (13).Although a number of studies have been performed on thylakoid lipids, their exact functional role still remains unclear, probably because lipids, unlike proteins, do not exhibit any catalytic property (17,24). The lipids are, however, thought to allow the maintenance of appropriate protein conformation that may be required for the optimal chloroplast functioning. In the present paper, we have attempted to characterize the nature and the extent of damage to the photosynthetic electron transport chain in chloroplasts isolated from stressed leaves and correlate them with the peroxidative degradation of the fatty acyl residues of thylakoid lipids. MATERIALS AND METHODS Plant MaterialWheat seeds (Triticum aestivum var HD-2329, Indian Agricultural Research Institute, New Delhi) were surface-sterilized with 0.1% HgC12 solution. They were germinated on moist filter paper in dark at 25°C for 48 h. After germination, the seedlings were transferred to a plant growth chamber maintained at 25°C and grown there under 14/10 h light-dark cycles. Light intensity during growth of the seedlings was 75 W_ m-2. The ...

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Section: In Vivo Chi Fluorescencementioning

confidence: 98%

Function of Photosynthetic Apparatus of Intact Wheat Leaves under High Light and Heat Stress and Its Relationship with Peroxidation of Thylakoid Lipids

Mishra¹,

Singhal²

1992

Plant Physiol.

147

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“…The effects of Cl--depletion have been studied by various techniques and through different observables, namely PS II-fluorescence [17,18], luminescence [18], a disturbed EPR-signal which, after Cl--repletion reversed into the EPR-'multiline'-signal of the normal Szstate [19-211 and P&-reduction [21]. The results are interpreted as follows.…”

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confidence: 99%

Chloride‐depletion of photosynthetic water oxidase

1993

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Chloride depletion blocks the normal four-step progress of photosynthetic water oxidation. We studied proton release in chloride-depleted thylakoids which were dark-adapted and excited by flashing light. Proton release was blocked from the second flash on, possibly leaving an uncompensated positive charge in the catalytic centre. The reduction of P&, by Tyrz was still very rapid (*: lo,@. From the third flash on, P&, was reduced more slowly (70 @200 ps), and by an electrogenic back-reaction. The uncompensated positive charge may be the reason why the rapid reduction of P&, by Tyrz is prevented and the transmembrane charge-pair recombination is facilitated.

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“…It seems clear that the 17,24 kD PSII extrinsic polypeptides are not directly required in the ligation of the polynuclear Mn complex (11,13,18,34) or for cycling of the S-states2 of 02 evolution (12,(35)(36)(37). It also is apparent (11,13,18,19) that these polypeptides somehow modulate the concentration of Clrequired for the S2-S3 (20,25,36,45) or the S3--(S4)--S0 + 02 transitions. (40).…”

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confidence: 99%

Studies on 17,24 kD Depleted Photosystem II Membranes

Cammarata

Cheniae²

1987

Plant Physiol.

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Analyses were made of the effects of extraction of the 17,24 kilodalton extrinsic proteins from spinach versus wheat photosystem II (PSII) membranes on Ca abundance and 02 evolution capacity determined in the absence and presence of either ClO or Ca22. Extraction of these proteins from spinach PSII routinely diminished steady state 02 evolution by about 70% when assayed in the presence ofsufficient Cl1. Additionally, 02 evolution of 17,24 kilodalton-less spinach PSI1 membranes showed about 2-fold more enhancement by Ca22 than by Cl-during assay. When the same extraction and assay procedures were applied to wheat PSII membranes, we observed, in contrast to 17,24 kilodalton-less spinach PSII, only about 50% inhibition of 02 evolution and about 2-fold greater enhancement by Cl-than by Ca21. Irrespective of differences in the magnitude of enhancement of 02 evolution by Ca2' versuC a-in spinach versus wheat, the K., values for Cl-(about 1.7 millimolar) and Ca2l (about 1.5 millimolar) were similar for both type preparations. The abundance of Ca specifically associated with fully functional PSII (about 2 and about 3 Ca/200 chlorophyll for spinach and wheat, respectively) was diminished to about 1 per 200 chlorophyll upon 17.24 kilodalton protein depletion. Further treatment of wheat 17,24 kilodalton-less PSII in darkness with 2 molar NaClI/ millimolar ethyleneglycol-bis(O-aminoethyl ether)-N,N'-tetraacetic acid/20 micromolar A231872 made 02 evolution highly dependent on Ca2 addition, much like the 17,24 kilodaltonless spinach PSII. Analyses of this Ca2' effect on 02 evolution revealed both high (K. about 65 micromolar) and low (K. about 1.5 millimolar) affinity Ca2 sites in wheat 17,24 kilodalton-less PSII. The results suggest that during 17,24 kilodalton extraction by NaCl, spinach PSII is more susceptible than wheat PSII to loss of high affinity Ca and irreversible inhibition of 02 evolution.The realization of 02 evolving everted thylakoid vesicles (1, 21) and Triton X-100 prepared PSII membranes (3, 24), also having everted membrane orientation (14,24), has led to intensive research focused on defining the polypeptides essential for efficient functioning of the PSII/water oxidizing complex. Parallel research has been directed towards identifying which poly- 90% (4-7, 15, 16, 21, 25, 27) when determined in the presence of saturating concentrations of Cl-. Subsequently, it was shown (6,7,15,16) that addition of 10 to 20 mM Ca2+ to 17,24 kDless, Cl-sufficient spinach PSII membranes increased rates of 02 evolution as much as 4-to 6-fold to rates sometimes nearly equivalent to those observed with unextracted membranes. However, no Ca2' additions were necessary to observe substantial period-4 oscillations of the S-states with only about 25% disconnection of the S-state complexes from PSII traps (12).Conceivably, at least some of the rather large variability in extent of loss of 02 evolution following depletion of the 17,24 kD proteins could reflect inadvertent dissociation of high affinity Ca2`during extraction....

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Effects of chloride depletion on electron donation from the water-oxidizing complex to the photosystem II reaction center as measured by the microsecond rise of chlorophyll fluorescence in isolated pea chloroplasts

Cited by 98 publications

References 31 publications

Function of Photosynthetic Apparatus of Intact Wheat Leaves under High Light and Heat Stress and Its Relationship with Peroxidation of Thylakoid Lipids

Function of Photosynthetic Apparatus of Intact Wheat Leaves under High Light and Heat Stress and Its Relationship with Peroxidation of Thylakoid Lipids

Chloride‐depletion of photosynthetic water oxidase

Studies on 17,24 kD Depleted Photosystem II Membranes

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