Production of reactive oxygen species by photosystem II

Pospı́šil, Pavel

doi:10.1016/j.bbabio.2009.05.005

Cited by 314 publications

(192 citation statements)

References 91 publications

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“…To date, in vitro investigation of electron transport processes of PSII suggested ROS generation on the electron accepter and donor sides of PSII under the reducing and oxidizing conditions, respectively. However, these observations have yet to be confirmed in vivo (for review, see Pospíšil, 2009). Interestingly, high ROS generation in var2 is correlated with our finding that the less functional partial PSII complexes accumulate.…”

Section: Discussionmentioning

confidence: 99%

The Variegated Mutants Lacking Chloroplastic FtsHs Are Defective in D1 Degradation and Accumulate Reactive Oxygen Species

et al. 2009

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In the photosynthetic apparatus, a major target of photodamage is the D1 reaction center protein of photosystem II (PSII). Photosynthetic organisms have developed a PSII repair cycle in which photodamaged D1 is selectively degraded. A thylakoid membrane-bound metalloprotease, FtsH, was shown to play a critical role in this process. Here, the effect of FtsHs in D1 degradation was investigated in Arabidopsis (Arabidopsis thaliana) mutants lacking FtsH2 (yellow variegated2 [var2]) or FtsH5 (var1). Because these mutants are characterized by variegated leaves that sometimes complicate biochemical studies, we employed another mutation, fu-gaeri1 (fug1), that suppresses leaf variegation in var1 and var2 to examine D1 degradation. Twodimensional blue native PAGE showed that var2 has less PSII supercomplex and more PSII intermediate lacking CP43, termed RC47, than the wild type under normal growth light. Moreover, our histochemical and quantitative analyses revealed that chloroplasts in var2 accumulate significant levels of reactive oxygen species, such as superoxide radical and hydrogen peroxide. These results indicate that the lack of FtsH2 leads to impaired D1 degradation at the step of RC47 formation in PSII repair and to photooxidative stress even under nonphotoinhibitory conditions. Our in vivo D1 degradation assays, carried out by nonvariegated var2 fug1 and var1 fug1 leaves, demonstrated that D1 degradation was impaired in different light conditions. Taken together, our results suggest the important role of chloroplastic FtsHs, which was not precisely examined in vivo. Attenuated D1 degradation in the nonvariegated mutants also suggests that leaf variegation seems to be independent of the PSII repair.

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Section: Discussionmentioning

confidence: 99%

The Variegated Mutants Lacking Chloroplastic FtsHs Are Defective in D1 Degradation and Accumulate Reactive Oxygen Species

et al. 2009

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“…At high C i levels in the chloroplasts many electrons can be used for CO 2 fixation, and HCO − 3 in the lumen activates PSII so that it produces electrons at maximum efficiency. In contrast, at low CO 2 /HCO − 3 levels fewer electrons are needed, and the down-regulation of PSII by 20% (or more) helps to mitigate an overreduction of the plastoquinone pool, which reduces the risk of producing reactive oxygen species that are known to be damaging to enzymes involved in photosynthesis (39)(40)(41). Future studies will be needed to elucidate whether such a feedback loop is indeed operational.…”

Section: Discussion Hco −mentioning

confidence: 99%

Mobile hydrogen carbonate acts as proton acceptor in photosynthetic water oxidation

Koroidov

Shevela

Shutova

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Cyanobacteria, algae, and plants oxidize water to the O 2 we breathe, and consume CO 2 during the synthesis of biomass. Although these vital processes are functionally and structurally well separated in photosynthetic organisms, there is a long-debated role for CO 2 /HCO − 3 in water oxidation. Using membrane-inlet mass spectrometry we demonstrate that HCO − 3 acts as a mobile proton acceptor that helps to transport the protons produced inside of photosystem II by water oxidation out into the chloroplast's lumen, resulting in a light-driven production of O 2 and CO 2 . Depletion of HCO − 3 from the media leads, in the absence of added buffers, to a reversible down-regulation of O 2 production by about 20%. These findings add a previously unidentified component to the regulatory network of oxygenic photosynthesis and conclude the more than 50-y-long quest for the function of CO 2 / HCO − 3 in photosynthetic water oxidation.O xygenic photosynthesis in cyanobacteria, algae, and higher plants leads to the reduction of atmospheric CO 2 to energy-rich carbohydrates. The electrons needed for this process are extracted in a cyclic, light-driven process from water that is split into dioxygen (O 2 ) and protons. This reaction is catalyzed by a penta-μ-oxo bridged tetra-manganese calcium cluster (Mn 4 CaO 5 ) within the oxygen-evolving complex (OEC) of photosystem II (PSII) (1-4). The possible roles of inorganic carbon, C i ðC i = CO 2 ; H 2 CO 3 ; HCO − 3 ; CO 2− 3 Þ, in this process have been a controversial issue ever since Otto Warburg and Günter Krippahl (5) reported in 1958 that oxygen evolution by PSII strictly depends on CO 2 and therefore has to be based on the photolysis of H 2 CO 3 ("Kohlensäure") and not of water. These first experiments were indirect and, as became apparent later, were wrongly interpreted (6-8). Several research groups followed up on these initial results and identified two possible sites of C i interaction within PSII (reviewed in refs. 9-12). Functional and spectroscopic studies showed that HCO − 3 facilitates the reduction of the secondary plastoquinone electron acceptor (Q B ) of PSII by participating in the protonation of Q 2− B . Binding of HCO − 3 (or CO 2− 3 ) to the nonheme Fe between the quinones Q A and Q B was recently confirmed by X-ray crystallography (3,13,14). Despite this functional role at the acceptor side, the very tight binding of HCO − 3 to this site makes it impossible for the activity of PSII to be affected by changing the C i level of the medium; instead inhibitors such as formate need to be added to induce the acceptor-side effect (15). Consequently, the watersplitting electron-donor side of PSII has also been studied intensively (for recent reviews, see refs. 11 and 12). Although a tight binding of C i near the Mn 4 CaO 5 cluster is excluded on the basis of X-ray crystallography (3, 14), FTIR spectroscopy (16), and mass spectrometry (17, 18), the possibility that a weakly bound HCO − 3 affects the activity of PSII at the donor side remains a viable option (reviewed i...

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“…Although ROS are produced mainly by photosystem I, PSII contributes under certain circumstances to the overall formation of ROS in the thylakoid membrane (Pospíšil 2009). Salinity and high-temperature stress increases the production of ROS, such as O − 2 and H 2 O 2 (Mishra & Singhal 1993;Dat et al 1998), which are toxic to plants.…”

Section: Discussionmentioning

confidence: 99%

Changes in photosynthesis, chlorophyll fluorescence, and antioxidant enzymes of mulberry (Morus ssp.) in response to salinity and high-temperature stress

Huang

et al. 2013

Biologia

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Photosynthesis, chlorophyll (Chl) fluorescence, and antioxidant enzymes were measured in the mulberry (Morus spp.) cultivars Da 10, Hongguo 2, Anza 1, and Taiwan 72C002, which were subjected to salinity and high-temperature stress (STS; 0.1%, 0.3%, and 0.5% NaCl concentrations, 34.5• C day/night temperatures). Control plants were watered with 1 L of full-strength Hoagland's nutrient solution with no added NaCl. Net photosynthetic rate (PN), stomatal conductance (gs), and effective quantum yield of photosystem II photochemistry (ΦPSII) increased in Anza 1 and Taiwan 72C002 under 0.1% STS but decreased in Da 10 and Hongguo 2 compared with the control. However, all the above parameters, including Chl content, maximum quantum yield of photosystem II photochemistry (Fv/Fm), nonphotochemical quenching (NPQ), and maximum carboxylation velocity of Rubisco (Vcmax, decreased in Taiwan 72C002, Honggua 2, and Da 10 under 0.3% and 0.5% STS, suggesting that photoinhibition occurred under severe STS. Under STS, there were no significant changes in PN, Fv/Fm, ΦPSII, ascorbate peroxidase (APX) activity, superoxide dismutase (SOD) activity, catalase activity, superoxide anion radical (O − 2 ) content, malondialdehyde (MDA) content, soluble sugar content (SSC), and leaf biomass in Anza 1 even at 0.5% STS, showing that Anza 1 displays high resistance to STS. In addition, peroxidase activity was significantly higher in Anza 1 than in the other mulberry cultivars. Significant adverse effects of severe salinity on photosynthesis and Chl fluorescence parameters were observed in Da 10. Additionally, SOD, peroxidase, and APX activities were lower in Da 10, whereas O − 2 and MDA contents were higher in comparison with the other mulberry cultivars under 0.3% and 0.5% STS, suggesting that Da 10 had low resistance to STS. These results show that 0.1% STS had a positive effect on photosynthesis and Chl fluorescence parameters in Anza 1 and Taiwan 72C002, and higher peroxidase activity can to a certain extent explain the higher STS tolerance in Anza 1. Damages to DSM photosystems might be related to lower SOD, POD, and APX activities, which resulted in the accumulation of reactive oxygen species.Key words: antioxidant enzymes; chlorophyll fluorescence; gas exchange; proline content; soluble sugar content; superoxide anion radical Abbreviations: APX, ascorbate peroxidase; AQY, apparent quantum yield; Ca, atmospheric CO2 concentration; CE, carboxylation efficiency; Ci, intercellular CO2 concentration; Chl, chlorophyll; E, transpiration rate; F0, minimum fluorescence level; Fm, maximum fluorescence level; Fv/Fm, maximum quantum yield of photosystem II photochemistry; FS, steady-state yield of PSII fluorescence in the light; gs, stomatal conductance; Ls, stomatal limitation value; MDA, malondialdehyde; NPQ, non-photochemical quenching; O − 2 , superoxide anion radical; PAR, photosynthetically active radiation; PN, net photosynthetic rate; PPBS, potassium phosphate buffer solution; PSII, photosystem II; ΦPSII, effective quantum yield of p...

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Production of reactive oxygen species by photosystem II

Cited by 314 publications

References 91 publications

The Variegated Mutants Lacking Chloroplastic FtsHs Are Defective in D1 Degradation and Accumulate Reactive Oxygen Species

The Variegated Mutants Lacking Chloroplastic FtsHs Are Defective in D1 Degradation and Accumulate Reactive Oxygen Species

Mobile hydrogen carbonate acts as proton acceptor in photosynthetic water oxidation

Changes in photosynthesis, chlorophyll fluorescence, and antioxidant enzymes of mulberry (Morus ssp.) in response to salinity and high-temperature stress

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