Flash-Induced Oxygen Evolution and Other Oscillatory Processes

Shinkarev, Vladimir P.

doi:10.1007/1-4020-4254-x_25

Cited by 8 publications

(10 citation statements)

References 62 publications

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“…a limited availability of the native acceptors (PQ molecules) in these preparations (Shevela et al ). As a consequence, the magnitudes of the miss parameters obtained in the present study should be discussed in terms of equilibria of both electron‐donor‐ (oxidizing) and ‐acceptor (reducing) sides of PSII (Renger and Hanssum , Shinkarev ). The origin of this ‘birth defect’ of PSII caused by illumination was probed further by variable Chl fluorescence decay and thermoluminescence studies.…”

Section: Resultsmentioning

confidence: 93%

‘Birth defects’ of photosystem II make it highly susceptible to photodamage during chloroplast biogenesis

Shevela

Ananyev

Vatland

et al. 2019

Physiologia Plantarum

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High solar flux is known to diminish photosynthetic growth rates, reducing biomass productivity and lowering disease tolerance. Photosystem II (PSII) of plants is susceptible to photodamage (also known as photoinactivation) in strong light, resulting in severe loss of water oxidation capacity and destruction of the water‐oxidizing complex (WOC). The repair of damaged PSIIs comes at a high energy cost and requires de novo biosynthesis of damaged PSII subunits, reassembly of the WOC inorganic cofactors and membrane remodeling. Employing membrane‐inlet mass spectrometry and O2‐polarography under flashing light conditions, we demonstrate that newly synthesized PSII complexes are far more susceptible to photodamage than are mature PSII complexes. We examined these ‘PSII birth defects’ in barley seedlings and plastids (etiochloroplasts and chloroplasts) isolated at various times during de‐etiolation as chloroplast development begins and matures in synchronization with thylakoid membrane biogenesis and grana membrane formation. We show that the degree of PSII photodamage decreases simultaneously with biogenesis of the PSII turnover efficiency measured by O2‐polarography, and with grana membrane stacking, as determined by electron microscopy. Our data from fluorescence, QB‐inhibitor binding, and thermoluminescence studies indicate that the decline of the high‐light susceptibility of PSII to photodamage is coincident with appearance of electron transfer capability QA− → QB during de‐etiolation. This rate depends in turn on the downstream clearing of electrons upon buildup of the complete linear electron transfer chain and the formation of stacked grana membranes capable of longer‐range energy transfer.

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Section: Resultsmentioning

confidence: 93%

‘Birth defects’ of photosystem II make it highly susceptible to photodamage during chloroplast biogenesis

Shevela

Ananyev

Vatland

et al. 2019

Physiologia Plantarum

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“…In our experiments, the probability of double hits was zero because 4-ns laser flashes are too short to induce double turnovers. However, omission of double hits makes the model for the flash oxygen sequence simpler and therefore less flexible than models containing double hits (27). Because of the reduced flexibility, we found it no longer possible to fit the oxygen sequences if the miss probability was the same for all S states.…”

Section: Analysis Of Flash-induced O 2 Evolutionmentioning

confidence: 95%

Two-Electron Reactions S2QB →S0QB and S3QB →S1QB are Involved in Deactivation of Higher S States of the Oxygen-Evolving Complex of Photosystem II

Antal

Sarvikas

Tyystjärvi

2009

Biophysical Journal

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The oxygen-evolving complex of Photosystem II cycles through five oxidation states (S(0)-S(4)), and dark incubation leads to 25% S(0) and 75% S(1). This distribution cannot be reached with charge recombination reactions between the higher S states and the electron acceptor Q(B)(-). We measured flash-induced oxygen evolution to understand how S(3) and S(2) are converted to lower S states when the electron required to reduce the manganese cluster does not come from Q(B)(-). Thylakoid samples preconditioned to make the concentration of the S(1) state 100% and to oxidize tyrosine Y(D) were illuminated by one or two laser preflashes, and flash-induced oxygen evolution sequences were recorded at various time intervals after the preflashes. The distribution of the S states was calculated from the flash-induced oxygen evolution pattern using an extended Kok model. The results suggest that S(2) and S(3) are converted to lower S states via recombination from S(2)Q(B)(-) and S(3)Q(B)(-) and by a slow change of the state of oxygen-evolving complex from S(3) and S(2) to S(1) and S(0) in reactions with unspecified electron donors. The slow pathway appears to contain two-electron routes, S(2)Q(B) -->S(0)Q(B), and S(3)Q(B) -->S(1)Q(B). The two-electron reactions dominate in intact thylakoid preparations in the absence of chemical additives. The two-electron reaction was replaced by a one-electron-per-step pathway, S(3)Q(B) -->S(2)Q(B) -->S(1)Q(B) in PS II-enriched membrane fragments and in thylakoids measured in the presence of artificial electron acceptors. A catalase effect suggested that H(2)O(2) acts as an electron donor for the reaction S(2)Q(B) -->S(0)Q(B) but added H(2)O(2) did not enhance this reaction.

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“…It is well known that the oxygen-evolving complex (OEC), an integral part of the multicomponent pigment-protein complex called photosystem II (PSII), is responsible for the lightinduced water splitting and release of protons and oxygen molecules from water molecules (1). When dark-adapted material (higher plants, algae, and cyanobacteria) is exposed to a series of single turnover flashes, oxygen evolution is detected with typical period-four damped oscillation with maxima on the third and seventh flashes and with minima on the first and fifth flashes (2)(3)(4).…”

Section: Introductionmentioning

confidence: 99%

“…The influence of other mechanisms or electron transporters, which can contribute to misses, is often either neglected (Y D , cytochrome b 559 ) or implicitly included in the P680 1 Q À A recombination (e.g., as a final state of S 2 Q À A recombination). The majority of scientists agree that the misses should be unequal (4). Equal misses are, however, usually used in analysis of oxygen evolution because it provides a satisfactory fit of experimental data (9).…”

Section: Introductionmentioning

confidence: 99%

“…The oxygen oscillation can also be successfully simulated using mathematical modeling. This approach provides the best fit of the model parameters to specific experimental data (9) and can also result in an interesting hypothesis such as the suggestion of two internal cycles of the PSII characterized by different transition probabilities (4,7). But the mathematical modeling based only on the Kok model cannot describe or explain the molecular mechanism of the OEC oxidation or the electron transport from the OEC to the P680.…”

Section: Introductionmentioning

confidence: 99%

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Evidence for Intermediate S-States as Initial Phase in the Process of Oxygen-Evolving Complex Oxidation

Jablonský

Lazár

2008

Biophysical Journal

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We have analyzed flash-induced period-four damped oscillation of oxygen evolution and chlorophyll fluorescence with the aid of a kinetic model of photosystem II. We have shown that, for simulation of the period-four oscillatory behavior of oxygen evolution, it is essential to consider the so-called intermediate S-state as an initial phase of each of the S(n)-S(n+1), (n = 0, 1, 2, 3) transitions. The intermediate S-states are defined as [S(n)Y(Z)(ox)]-states (n = 0, 1, 2, 3) and are formed with rate constant k(iSn) approximately 1.5 x 10(6) s(-1), which was determined from comparison of theoretical predictions with experimental data. The assumed intermediate S-states shift the equilibrium in reaction P680(+)Y(Z)<-->P680Y(Z)(ox) more to the right and we suggest that kinetics of the intermediate S-states reflects a relaxation process associated with changes of the redox equilibrium in the above reaction. The oxygen oscillation is simulated without the miss and double-hit parameters, if the intermediate S-states, which are not the source of the misses or the double-hits, are included in the simulation. Furthermore, we have shown that the intermediate S-states, together with S(2)Q(A)(-) charge recombination, are prerequisites for the simulation of the period-four oscillatory behavior of the chlorophyll fluorescence.

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Flash-Induced Oxygen Evolution and Other Oscillatory Processes

Cited by 8 publications

References 62 publications

‘Birth defects’ of photosystem II make it highly susceptible to photodamage during chloroplast biogenesis

‘Birth defects’ of photosystem II make it highly susceptible to photodamage during chloroplast biogenesis

Two-Electron Reactions S2QB →S0QB and S3QB →S1QB are Involved in Deactivation of Higher S States of the Oxygen-Evolving Complex of Photosystem II

Evidence for Intermediate S-States as Initial Phase in the Process of Oxygen-Evolving Complex Oxidation

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