Tocopherol as singlet oxygen scavenger in photosystem II

Kruk, Jerzy; Holländer-Czytko, Heike; Oettmeier, Walter; Trebst, Achim

doi:10.1016/j.jplph.2005.04.020

Cited by 158 publications

(109 citation statements)

References 60 publications

(64 reference statements)

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“…This proves the antioxidant role of tocopherols in the protection of PSII structural organization under te development of oxidative stress in this alga [18,23,24].…”

Section: Fig 2 Oxidative Conversion Of α-Tocopherol оглядиsupporting

confidence: 57%

“…2). Tocopheroxyl radicals may be renewed with the help of antioxidant system, which consists of ascorbate and glutathione; renewals with the help of coenzyme Q or covalent interaction with free radicals with further formation of tocopherols, are also possible [16,17] [18,19]. The products of tocopherol oxidation in this case are not recycled and are lost [10].…”

Section: Antioxidant Properties Of Tocopherolsmentioning

confidence: 99%

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Functions of tocopherols in the cells of plants and other photosynthetic organisms

Mokrosnop¹

2014

Ukr.Biochem.J

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“…This proves the antioxidant role of tocopherols in the protection of PSII structural organization under te development of oxidative stress in this alga [18,23,24].…”

Section: Fig 2 Oxidative Conversion Of α-Tocopherol оглядиsupporting

confidence: 57%

Section: Antioxidant Properties Of Tocopherolsmentioning

confidence: 99%

Functions of tocopherols in the cells of plants and other photosynthetic organisms

Mokrosnop¹

2014

Ukr.Biochem.J

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“…Since it is difficult for plastoquinones to enter the cell through the plasma membrane and the periplasmic space, we carried out this investigation using thylakoid membranes isolated from sulfide-induced wild-type and mutant cells. PQ-1, a water-soluble short-isoprenoid-chain plastoquinone, was used, which is an appropriate analogue of the internal quinone in in vitro investigations (51). Following the changes in the absorption at 257 nm of the plastoquinol, formed by the reduction of the added plastoquinone, we found plastoquinol formation in thylakoid samples isolated from induced WT cells, whereas this feature could not be observed using the similarly treated thylakoids from the mutant lacking the suo operon (Fig.…”

Section: Resultsmentioning

confidence: 94%

Coregulated Genes Link Sulfide:Quinone Oxidoreductase and Arsenic Metabolism in Synechocystis sp. Strain PCC6803

et al. 2014

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Although the biogeochemistry of the two environmentally hazardous compounds arsenic and sulfide has been extensively investigated, the biological interference of these two toxic but potentially energy-rich compounds has only been hypothesized and indirectly proven. Here we provide direct evidence for the first time that in the photosynthetic model organism Synechocystis sp. strain PCC6803 the two metabolic pathways are linked by coregulated genes that are involved in arsenic transport, sulfide oxidation, and probably in sulfide-based alternative photosynthesis. Although Synechocystis sp. strain PCC6803 is an obligate photoautotrophic cyanobacterium that grows via oxygenic photosynthesis, we discovered that specific genes are activated in the presence of sulfide or arsenite to exploit the energy potentials of these chemicals. These genes form an operon that we termed suoRSCT, located on a transposable element of type IS4 on the plasmid pSYSM of the cyanobacterium. suoS (sll5036) encodes a light-dependent, type I sulfide:quinone oxidoreductase. The suoR (sll5035) gene downstream of suoS encodes a regulatory protein that belongs to the ArsR-type repressors that are normally involved in arsenic resistance. We found that this repressor has dual specificity, resulting in 200-fold induction of the operon upon either arsenite or sulfide exposure. The suoT gene encodes a transmembrane protein similar to chromate transporters but in fact functioning as an arsenite importer at permissive concentrations. We propose that the proteins encoded by the suoRSCT operon might have played an important role under anaerobic, reducing conditions on primordial Earth and that the operon was acquired by the cyanobacterium via horizontal gene transfer.

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“…The ␣-tocopherol level in the npq1 lor1 strain followed the same trend as that of chlorophyll a, staying at a constant level for the first 12 h but exhibiting a dramatic decrease at 24 and 48 h. In contrast, the ␤-tocopherol level in the vte3 npq1 lor1 strain decreased in the first 12 h before remaining relatively constant. Because tocopherol has been shown to protect the D1 reaction center protein from degradation by singlet oxygen generated in photosystem II during oxidative stress (26,53), we investigated D1 protection by different forms of tocopherol in the npq1 lor1 and vte3 npq1 lor1 strains. Cultures exposed to high light were used for immunoblotting and quantitation of total D1 (Fig.…”

Section: Resultsmentioning

confidence: 99%

Replacement of α-Tocopherol by β-Tocopherol Enhances Resistance to Photooxidative Stress in a Xanthophyll-Deficient Strain of Chlamydomonas reinhardtii

et al. 2009

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Tocopherols (vitamin E) comprise a class of lipid-soluble antioxidants synthesized only in plants, algae, and some cyanobacteria. The majority of tocopherols in photosynthetic cells is in the ␣ form, which has the highest vitamin E activity in humans, whereas the ␤, ␥, and ␦ forms normally account for a small percentage of total tocopherols. The antioxidant activities of these forms of tocopherol differ depending on the experimental system, and their relative activities in vivo are unclear. In a screen for suppressors of the xanthophyll-deficient npq1 lor1 double mutant of Chlamydomonas reinhardtii, we isolated a vte3 mutant lacking ␣-tocopherol but instead accumulating ␤-tocopherol. The vte3 mutant contains a mutation in the homolog of a 2-methyl-6-phytyl-1,4-benzoquinone methyltransferase gene found in plants. The vte3 npq1 lor1 triple mutant with ␤-tocopherol survived better under photooxidative stress than did the npq1 lor1 mutant, but the vte3 mutant on its own did not have an obvious phenotype. Following transfer from low light to high light, the triple mutant showed a higher efficiency of photosystem II, a higher level of cell viability, and a lower level of lipid peroxide, a marker for oxidative stress, than did the npq1 lor1 mutant. After high-light transfer, the level of the photosystem II reaction center protein, D1, was also higher in the vte3 npq1 lor1 mutant, but the rate of D1 photodamage was not significantly different from that of the npq1 lor1 mutant. Taken together, these results suggest that the replacement of ␣-tocopherol by ␤-tocopherol in a xanthophyll-deficient strain of Chlamydomonas reinhardtii contributes to better survival under conditions of photooxidative stress.

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Tocopherol as singlet oxygen scavenger in photosystem II

Cited by 158 publications

References 60 publications

Functions of tocopherols in the cells of plants and other photosynthetic organisms

Functions of tocopherols in the cells of plants and other photosynthetic organisms

Coregulated Genes Link Sulfide:Quinone Oxidoreductase and Arsenic Metabolism in Synechocystis sp. Strain PCC6803

Replacement of α-Tocopherol by β-Tocopherol Enhances Resistance to Photooxidative Stress in a Xanthophyll-Deficient Strain of Chlamydomonas reinhardtii

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