Scavenging of Superoxide Generated in Photosystem I by Plastoquinol and Other Prenyllipids in Thylakoid Membranes †

Bielefeld University, Bielefeld, North Rhine-Westphalia, Germany
Biochemistry (Impact Factor: 3.02). 08/2003; 42(28):8501-5. DOI: 10.1021/bi034036q
Source: PubMed


We have examined scavenging of a superoxide by various prenyllipids occurring in thylakoid membranes, such as plastoquinone-9, alpha-tocopherolquinone, their reduced forms, and alpha-tocopherol, measuring oxygen uptake in hexane-extracted and untreated spinach thylakoids with a fast oxygen electrode under flash-light illumination. The obtained results demonstrated that all the investigated prenyllipids showed the superoxide scavenging properties, and plastoquinol-9 was the most active in this respect. Plastoquinol-9 formed in thylakoids as a result of enzymatic reduction of plastoquinone-9 by ferredoxin-plastoquinone reductase was even more active than the externally added plastoquinol-9 in the investigated reaction. Scavenging of superoxide by plastoquinol-9 and other prenyllipids could be important for protecting membrane components against the toxic action of superoxide. Moreover, our results indicate that vitamin K(1) is probably the most active redox component of photosystem I in the generation of superoxide within thylakoid membranes.

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Available from: Kazimierz Strzalka, Mar 10, 2015
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    • "The terminal acceptors F X , F A , and F B likely function as electron donors to oxygen [16]. It has also been suggested that phylloquinone A 1 , a secondary electron acceptor in PS I, might donate an electron to oxygen within the thylakoid membrane [17] [18]. O 2 ÅÀ can also be generated on the acceptor side of PS II [19] [20]. "
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    ABSTRACT: Plastoquinol (PQH2-9) and plastoquinone (PQ-9) mediate photosynthetic electron transfer. We isolated PQH2-9 from thylakoid membranes, purified it with HPLC, subjected the purified PQH2-9 to singlet oxygen ((1)O2) and analyzed the products. The main reaction of (1)O2 with PQH2-9 in methanol was found to result in formation of PQ-9 and H2O2, and the amount of H2O2 produced was essentially the same as the amount of oxidized PQH2-9. Formation of H2O2 in the reaction between (1)O2 and PQH2-9 may be an important source of H2O2 within the lipophilic thylakoid membrane. Copyright © 2015. Published by Elsevier B.V.
    Full-text · Article · Feb 2015 · FEBS Letters
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    • "Phylloquinones (PhQ), which occupy the quinone-binding sites of PS I (A 1 -sites), and the [4Fe–4S] cluster F X are characterized by rather negative E m values and are capable of O 2 reduction within the membrane (Fig. 1B). PhQ [21] [22] and F X [23] were proposed to be O 2 reducing cofactors, however there is no direct evidence proving their involvement in O 2 reduction. "
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    ABSTRACT: O2 reduction was investigated in photosystem I (PSI) complexes isolated from cyanobacteria Synechocystissp.PCC6803 wild type (WT) and menB mutant strain, which is unable to synthesize phylloquinone and contains plastoquinone at the quinone-binding site A1. PSI complexes from WT and menB mutant exhibited different dependencies of O2 reduction on light intensity, namely, the values of O2 reduction rate in WT did not reach saturation at high intensities, in contrast to the values in menB mutant. The obtained results suggest the immediate phylloquinone involvement in the light-induced O2 reduction by PSI.
    Full-text · Article · Oct 2014 · FEBS Letters
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    • "In contrast to animal membranes, only one such product has been reported to accumulate in plants, namely α-tocopherol quinol (α-TQH2) (Figure 1B) (Dellapenna and Kobayashi, 2008; Mene-Saffrane and Dellapenna, 2010). A part from being a product of tocopherol oxidation, several functions for α-TQH2 have been proposed: dissipation of excess energy, protection of PSII against photoinhibition (Kruk et al., 2000, 2003; Munne-Bosch, 2005) as well as a strong antioxidant activity (Kruk and Trebst, 2008; Nowicka and Kruk, 2010). "
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    ABSTRACT: Plants are exposed to ever changing light environments and continuously forced to adapt. Excessive light intensity leads to the production of reactive oxygen species that can have deleterious effects on photosystems and thylakoid membranes. To limit damage, plants increase the production of membrane soluble antioxidants such as tocopherols. Here, untargeted lipidomics after high light treatment showed that among hundreds of lipid compounds alpha-tocopherol is the most strongly induced, underscoring its importance as an antioxidant. As part of the antioxidant mechanism, α-tocopherol undergoes a redox cycle involving oxidative opening of the chromanol ring. The only enzyme currently known to participate in the cycle is tocopherol cyclase (VTE1, At4g32770), that re-introduces the chromanol ring of α-tocopherol. By mutant analysis, we identified the NAD(P)H-dependent quinone oxidoreductase (NDC1, At5g08740) as a second enzyme implicated in this cycle. NDC1 presumably acts through the reduction of quinone intermediates preceding cyclization by VTE1. Exposure to high light also triggered far-ranging changes in prenylquinone composition that we dissect herein using null mutants and lines overexpressing the VTE1 and NDC1 enzymes.
    Full-text · Article · Jun 2014 · Frontiers in Plant Science
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