scholarly journals The role of inactive photosystem–II–mediated quenching in a last–ditch community defence against high light stress in vivo

2002 ◽  
Vol 357 (1426) ◽  
pp. 1441-1450 ◽  
Author(s):  
Wah Soon Chow ◽  
Hae–Youn Lee ◽  
Youn–Il Park ◽  
Yong–Mok Park ◽  
Yong–Nam Hong ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Light Stress ◽  
Extreme Environments ◽  
Photosynthetic Apparatus ◽  
Optimal Operation ◽  
Residual Fraction ◽  
Photosynthetic Membrane ◽  
Number Of Factors ◽  
Inactive Photosystem Ii

Photoinactivation of photosystem II (PSII), the light–induced loss of ability to evolve oxygen, is an inevitable event during normal photosynthesis, exacerbated by saturating light but counteracted by repair via new protein synthesis. The photoinactivation of PSII is dependent on the dosage of light: in the absence of repair, typically one PSII is photoinactivated per 10 7 photons, although the exact quantum yield of photoinactivation is modulated by a number of factors, and decreases as fewer active PSII targets are available. PSII complexes initially appear to be photoinactivated independently; however, when less than 30% functional PSII complexes remain, they seem to be protected by strongly dissipative PSII reaction centres in several plant species examined so far, a mechanism which we term ‘inactive PSII–mediated quenching‘. This mechanism appears to require a pH gradient across the photosynthetic membrane for its optimal operation. The residual fraction of functional PSII complexes may, in turn, aid in the recovery of photoinactivated PSII complexes when conditions become less severe. This mechanism may be important for the photosynthetic apparatus in extreme environments such as those experienced by over–wintering evergreen plants, desert plants exposed to drought and full sunlight and shade plants in sustained sunlight.

Phytotoxic Action of Paraquat on the Photosynthetic Apparatus

1978 ◽  
Vol 33 (9-10) ◽  
pp. 688-694 ◽  
Author(s):  
Peter Böger ◽  
K. J. Kunert
Keyword(s):  
Photosystem Ii ◽  
Redox Reactions ◽  
Photosynthetic Apparatus ◽  
Membrane System ◽  
Culture Conditions ◽  
Terminal Part ◽  
Photosynthetic Membrane ◽  
Redox Chain ◽  
Chlorophyll Bleaching ◽  
Chloroplast Volume

Abstract Treatment of microalgae (Bumilleriopsis) with paraquat (1,1-dimethyl-4,4-dipyridylium dichloride) under culture conditions in the light for 20 or 160 h leads to light-induced oxygen uptake and more or less severe chlorophyll bleaching, which is accompanied by formation of malondial-dehyde. The ratio of chlorophyll to packed chloroplast volume remains about the same as that of the control, presumably indicating destruction of membranes concurrently with pigments. Unre­lated to retardation of growth, degree of bleaching or to the formation of malondialdehyde quite a uniform degree of inactivation (≈ 50%) of partial redox reactions is observed in the region of photosystem II and I except for the terminal part of photosystem I (pigment 700 → NADP+) . The action of paraquat in the cell centers primarily on the photosynthetic membrane system and redox chain.

scholarly journals A novel method produces native light-harvesting complex II aggregates from the photosynthetic membrane revealing their role in nonphotochemical quenching

2020 ◽  
Vol 295 (51) ◽  
pp. 17816-17826
Author(s):  
Mahendra K. Shukla ◽  
Akimasa Watanabe ◽  
Sam Wilson ◽  
Vasco Giovagnetti ◽  
Ece Imam Moustafa ◽  
...  
Keyword(s):  
Light Harvesting ◽  
Higher Plants ◽  
Photosynthetic Apparatus ◽  
Preparative Method ◽  
Nonphotochemical Quenching ◽  
Photosynthetic Membrane ◽  
Purification Method ◽  
Ps Ii ◽  
Core Proteins

Nonphotochemical quenching (NPQ) is a mechanism of regulating light harvesting that protects the photosynthetic apparatus from photodamage by dissipating excess absorbed excitation energy as heat. In higher plants, the major light-harvesting antenna complex (LHCII) of photosystem (PS) II is directly involved in NPQ. The aggregation of LHCII is proposed to be involved in quenching. However, the lack of success in isolating native LHCII aggregates has limited the direct interrogation of this process. The isolation of LHCII in its native state from thylakoid membranes has been problematic because of the use of detergent, which tends to dissociate loosely bound proteins, and the abundance of pigment–protein complexes (e.g. PSI and PSII) embedded in the photosynthetic membrane, which hinders the preparation of aggregated LHCII. Here, we used a novel purification method employing detergent and amphipols to entrap LHCII in its natural states. To enrich the photosynthetic membrane with the major LHCII, we used Arabidopsis thaliana plants lacking the PSII minor antenna complexes (NoM), treated with lincomycin to inhibit the synthesis of PSI and PSII core proteins. Using sucrose density gradients, we succeeded in isolating the trimeric and aggregated forms of LHCII antenna. Violaxanthin- and zeaxanthin-enriched complexes were investigated in dark-adapted, NPQ, and dark recovery states. Zeaxanthin-enriched antenna complexes showed the greatest amount of aggregated LHCII. Notably, the amount of aggregated LHCII decreased upon relaxation of NPQ. Employing this novel preparative method, we obtained a direct evidence for the role of in vivo LHCII aggregation in NPQ.

scholarly journals Involvement of the HtrA family of proteases in the protection of the cyanobacterium Synechocystis PCC 6803 from light stress and in the repair of photosystem II

2002 ◽  
Vol 357 (1426) ◽  
pp. 1461-1468 ◽  
Author(s):  
Paulo Silva ◽  
Young–Jun Choi ◽  
Hanadi A. G. Hassan ◽  
Peter J. Nixon
Keyword(s):  
Photosystem Ii ◽  
Light Stress ◽  
High Light ◽  
Triple Mutant ◽  
D1 Polypeptide ◽  
In The Wild ◽  
D1 Turnover ◽  
Major Target ◽  
Pcc 6803

Photosystem II (PSII) is prone to irreversible light–induced damage, with the D1 polypeptide a major target. Repair processes operate in the cell to replace a damaged D1 subunit within the complex with a newly synthesized copy. As yet, the molecular details of PSII repair are relatively obscure despite the critical importance of this process for maintaining PSII activity and cell viability. We are using the cyanobacterium Synechocystis sp. PCC 6803 to identify the various proteases and chaperones involved in D1 turnover in vivo . Two families of proteases are being studied: the FtsH family (four members) of Zn 2+ –activated nucleotide–dependent proteases; and the HtrA (or DegP) family (three members) of serine–type proteases. In this paper, we report the results of our studies on a triple mutant in which all three copies of the htrA gene family have been inactivated. Growth of the mutant on agar plates was inhibited at high light intensities, especially in the presence of glucose. Oxygen evolution measurements indicated that, under conditions of high light, the rate of synthesis of functional PSII was less in the mutant than in the wild–type. Immunoblotting experiments conducted on cells blocked in protein synthesis further indicated that degradation of D1 was slowed in the mutant. Overall, our observations indicate that the HtrA family of proteases are involved in the resistance of Synechocystis 6803 to light stress and play a part, either directly or indirectly, in the repair of PSII in vivo .

Regulation of photosynthesis by chloroplast protein phosphorylation

1983 ◽  
Vol 302 (1108) ◽  
pp. 113-125 ◽  
Keyword(s):  
Photosystem Ii ◽  
Excitation Energy ◽  
Photosystem I ◽  
Metabolic Pathways ◽  
Redox State ◽  
Calvin Cycle ◽  
Photosynthetic Membrane ◽  
Regulation Of Photosynthesis

Several polypeptides of the chloroplast photosynthetic membrane are reversibly phosphorylated in vivo and in vitro . The most conspicuous phosphoproteins belong to the light-harvesting chlorophyll a/b complex (LHC), which accounts for about half of the photons absorbed by the pigments of the photosynthetic membrane and can transfer excitation energy to either photosystem I or photosystem II. Phosphorylation of LHC increases (and dephosphorylation decreases) the proportion of excitation energy transferred to photosystem I at the expense of photosystem II. The LHC kinase is activated in vivo and in vitro by overexcitation of photosystem II and inactivated by overexcitation of photosystem I. The redox state of the plastoquinone pool governs the activity of the kinase and enables the photosynthetic membrane to detect and then correct any imbalance in the rate of excitation of the two photosystems. Reversible phosphorylation of LHC also enables the chloroplast to regulate the relative rates of cyclic and non-cyclic electron transport and thereby coordinates the rates of synthesis of ATP and NADPH with the demands of the Calvin cycle and other metabolic pathways operating within the organelle.

Quality control of Photosystem II under light stress – turnover of aggregates of the D1 protein in vivo

2005 ◽  
Vol 84 (1-3) ◽  
pp. 29-33 ◽  
Author(s):  
Satoshi Ohira ◽  
Noriko Morita ◽  
Hwa-Jin Suh ◽  
Jin Jung ◽  
Yasusi Yamamoto
Keyword(s):  
Quality Control ◽  
Photosystem Ii ◽  
Light Stress ◽  
D1 Protein ◽  
Control Of Photosystem Ii

SO2 Injury in Intact Leaves, as Detected by Chlorophyll Fluorescence

1988 ◽  
Vol 43 (3-4) ◽  
pp. 269-274 ◽  
Author(s):  
Wolfgang Schmidt ◽  
Ulrich Schreiber ◽  
Wolfgang Urbach
Keyword(s):  
Chlorophyll Fluorescence ◽  
Photosystem Ii ◽  
Calvin Cycle ◽  
Photosynthetic Apparatus ◽  
Enzymatic Reactions ◽  
Decay Kinetics ◽  
Saturation Pulse ◽  
Induction Kinetics ◽  
Fluorescence Measurements

The effects of short-time fumigation (0-60 min) of intact spinach leaves with SO2 (2 ppm) on the photosynthetic apparatus were investigated. A rather high SO2 concentration was applied to monitor immediate effects on the fluorescence behaviour with the influence of repair processes or secondary types of damage being minimized. Three different types of in vivo chlorophyll fluorescence measurements were used: Rapid induction kinetics (Kautsky effect), slow induction kinetics with repetitive application of saturation pulses (saturation pulse method), and decay kinetics following a single turnover saturating flash. The slow induction kinetics with repetitive application of saturation pulses reacts in the most sensitive way indicating a primary damage at the level of the enzymatic reactions of the Calvin cycle. It is suggested that stromal acidification upon SO2 uptake interferes with light activation of Calvin cycle enzymes. With longer fumigation times also damage at the level of photosystem II becomes apparent: A decrease in variable fluorescence yield reflects a lowering of photosystem II quantum yield, and the slowing down of fluorescence relaxation kinetics reveals an effect on the secondary electron transport from Qᴀ to Qв. The detrimental effects of SO2 depend to a great extent on the application of light during fumigation. Besides a light requirement for SO2 uptake by stomata opening also the possibility of photoinhibitory damage is discussed. The susceptibility of leaves to photoinhibition may increase with a lowering of Calvin cycle activity by SO2.

scholarly journals Zeaxanthin-dependent nonphotochemical quenching does not occur in photosystem I in the higher plant Arabidopsis thaliana

2017 ◽  
Vol 114 (18) ◽  
pp. 4828-4832 ◽  
Author(s):  
Lijin Tian ◽  
Pengqi Xu ◽  
Volha U. Chukhutsina ◽  
Alfred R. Holzwarth ◽  
Roberta Croce
Keyword(s):  
Arabidopsis Thaliana ◽  
Photosystem I ◽  
Light Stress ◽  
Photosynthetic Apparatus ◽  
Nonphotochemical Quenching ◽  
High Light ◽  
Higher Plant ◽  
Fluorescence Measurements ◽  
Kinetics Of

Nonphotochemical quenching (NPQ) is the process that protects the photosynthetic apparatus of plants and algae from photodamage by dissipating as heat the energy absorbed in excess. Studies on NPQ have almost exclusively focused on photosystem II (PSII), as it was believed that NPQ does not occur in photosystem I (PSI). Recently, Ballottari et al. [Ballottari M, et al. (2014) Proc Natl Acad Sci USA 111:E2431–E2438], analyzing PSI particles isolated from an Arabidopsis thaliana mutant that accumulates zeaxanthin constitutively, have reported that this xanthophyll can efficiently induce chlorophyll fluorescence quenching in PSI. In this work, we have checked the biological relevance of this finding by analyzing WT plants under high-light stress conditions. By performing time-resolved fluorescence measurements on PSI isolated from Arabidopsis thaliana WT in dark-adapted and high-light–stressed (NPQ) states, we find that the fluorescence kinetics of both PSI are nearly identical. To validate this result in vivo, we have measured the kinetics of PSI directly on leaves in unquenched and NPQ states; again, no differences were observed. It is concluded that PSI does not undergo NPQ in biologically relevant conditions in Arabidopsis thaliana. The possible role of zeaxanthin in PSI photoprotection is discussed.

scholarly journals Identification of hydroxy-plastochromanol in Arabidopsis leaves.

2010 ◽  
Vol 57 (1) ◽  
Author(s):  
Renata Szymańska ◽  
Jerzy Kruk
Keyword(s):  
Photosystem Ii ◽  
Singlet Oxygen ◽  
Light Stress ◽  
High Light ◽  
Low Light ◽  
High Light Stress ◽  
First Time

In the present study we have identified hydroxy-plastochromanol in plants for the first time. This compound was found both in low light and high light-grown Arabidopsis plants, however, under high light stress its level was considerably increased. Hydroxy-plastochromanol accumulated also during ageing of leaves of low light-grown plants, similarly as in the case of other prenyllipids. Our results indicate that hydroxy-plastochromanol found in leaves is probably formed as a result of plastochromanol oxidation by singlet oxygen generated in photosystem II during photosynthesis. These data also support the hypothesis that plastochromanol is an efficient antioxidant in vivo, similarly as tocopherols and plastoquinol.

Structural analysis of the photosynthetic membrane from Ectothiorhodospira halochloris

1983 ◽  
Vol 41 ◽  
pp. 740-741
Author(s):  
H. Engelhardt ◽  
R. Guckenberger ◽  
W. Baumeister
Keyword(s):  
Lattice Structure ◽  
Bacterial Species ◽  
Hexagonal Lattice ◽  
Reaction Centre ◽  
Photosynthetic Membrane ◽  
Rhodopseudomonas Viridis ◽  
Photosynthetic Membranes ◽  
Ectothiorhodospira Halochloris ◽  
Main Components

Bacterial photosynthetic membranes contain, apart from lipids and electron transport components, reaction centre (RC) and light harvesting (LH) polypeptides as the main components. The RC-LH complexes in Rhodopseudomonas viridis membranes are known since quite seme time to form a hexagonal lattice structure in vivo; hence this membrane attracted the particular attention of electron microscopists. Contrary to previous claims in the literature we found, however, that 2-D periodically organized photosynthetic membranes are not a unique feature of Rhodopseudomonas viridis. At least five bacterial species, all bacteriophyll b - containing, possess membranes with the RC-LH complexes regularly arrayed. All these membranes appear to have a similar lattice structure and fine-morphology. The lattice spacings of the Ectothiorhodospira haloohloris, Ectothiorhodospira abdelmalekii and Rhodopseudomonas viridis membranes are close to 13 nm, those of Thiocapsa pfennigii and Rhodopseudomonas sulfoviridis are slightly smaller (∼12.5 nm).

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