Antimycin A effect on the electron transport in chloroplasts of two Chlamydomonas reinhardtii strains
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ORIGINAL ARTICLE
Antimycin A effect on the electron transport in chloroplasts of two Chlamydomonas reinhardtii strains Taras K. Antal • Galina P. Kukarskikh • Alexander A. Bulychev • Esa Tyystja¨rvi • Tatyana Krendeleva
Received: 17 December 2012 / Accepted: 7 January 2013 Ó Springer-Verlag Berlin Heidelberg 2013
Abstract The effects of antimycin A on the redox state of plastoquinone and on electron donation to photosystem I (PS I) were studied in sulfur-deprived Chlamydomonas reinhardtii cells of the strains cc406 and 137c. We found that this reagent suppresses cyclic electron flow around PS I in the cc406 strain, whereas this inhibitory effect was completely absent in the 137c strain. In the latter strain, antimycin A induced rapid reduction of plastoquinone in the dark and considerably enhanced the rate of electron donation to P700? in the dark. Importantly, neither myxothiazol, an inhibitor of mitochondrial respiration, FCCP, a protonophore, nor propyl gallate, an inhibitor of the plastid terminal oxidase, induced such a strong effect like antimycin A. The results indicate that in the chloroplast of the 137c strain, antimycin A has a site of action outside of the machinery of cyclic electron flow.
ETC FCCP
Keywords Antimycin A Chlamydomonas Hydrogen Sulfur deprivation
Antimycin A (AA) is an antibiotic that interferes with specific proteins in the electron transport chain (ETC) (Lennon 1973). Usually AA is used as an inhibitor of ubiquinol oxidation by the cytochrome bc1 complex in the mitochondrion; AA prevents the formation of a proton gradient across the inner membrane, thereby prohibiting oxidative phosphorylation. Moreover, AA has several targets of action in the chloroplast (see a scheme in Fig. 1). In higher plants, AA slows down cyclic electron flow around PS I (CEF); in CEF electrons are cycled from ferredoxin (Fd) to plastoquinone (PQ) and then back to Fd via PS I. AA also inhibits the photophosphorylation coupled to CEF (Tagawa et al. 1963; Moss and Bendall 1984; Cleland and Bendall 1992). CEF can be activated under various stress conditions when the metabolic requirements of reducing equivalents in the chloroplast are limited, e.g. due to the low capacity for carbon fixation (Rumeau et al. 2007). CEF may operate
Abbreviations AA Antimycin A DCMU3 3-(3,4-dichlorophenyl)-1,1-dimethylurea CEF Cyclic electron flow around PS I FQR Ferredoxin-quinone reductase Chl Chlorophyll T. K. Antal (&) G. P. Kukarskikh A. A. Bulychev T. Krendeleva Biological Faculty, Moscow State University, Vorobyevi Gory, 119992 Moscow, Russia e-mail: [email protected] E. Tyystja¨rvi Department of Biochemistry and Food Chemistry Molecular Plant Biology, University of Turku, 20014 Turku, Finland
Fd FNR Mxt MV NDH PPFD PQ Pc PTOX
Electron transport chain Carbonylcyanide-p-trifluoromethoxyphenylhydrazone Ferredoxin Ferredoxin-NADP reductase Myxothyazol Methyl viologen NADH dehydrogenase Photosynthetic photon flux density Plastoquinon Plastocyanin Plastid terminal oxidase
Introduction
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Planta
Fig. 1 A scheme
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