Effect of Cationic Plastoquinone SkQ1 on Electron Transfer Reactions in Chloroplasts and Mitochondria from Pea Seedlings

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V. D. Samuilov^* and D. B. Kiselevsky

Lomonosov Moscow State University, Faculty of Biology, 119991 Moscow, Russia; fax: +7 (495) 939-3807; E-mail: vdsamuilov@mail.ru

^* To whom correspondence should be addressed.

Received August 14, 2014; Revision received December 4, 2014

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Plastoquinone bound with decyltriphenylphosphonium cation (SkQ1) penetrating through the membrane in nanomolar concentrations inhibited H₂O₂ generation in cells of epidermis of pea seedling leaves that was detected by the fluorescence of 2′,7′-dichlorofluorescein. Photosynthetic electron transfer in chloroplasts isolated from pea leaves is suppressed by SkQ1 at micromolar concentrations: the electron transfer in chloroplasts under the action of photosystem II or I (with silicomolybdate or methyl viologen as electron acceptors, respectively) is more sensitive to SkQ1 than under the action of photosystem II + I (with ferricyanide or p-benzoquinone as electron acceptors). SkQ1 reduced by borohydride is oxidized by ferricyanide, p-benzoquinone, and, to a lesser extent, by silicomolybdate, but not by methyl viologen. SkQ1 is not effective as an electron acceptor supporting O₂ evolution from water in illuminated chloroplasts. The data on suppression of photosynthetic O₂ evolution or consumption show that SkQ1, similarly to phenazine methosulfate, causes conversion of the chloroplast redox-chain from non-cyclic electron transfer mode to the cyclic mode without O₂ evolution. Oxidation of NADH or succinate in mitochondria isolated from pea roots is stimulated by SkQ1.

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KEY WORDS: programmed cell death, mitochondria-targeted quinones, SkQ1, electron transfer, retardation in chloroplasts, stimulation in mitochondria

DOI: 10.1134/S0006297915040045

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