Antisense expression of mitochondrial ATP synthase subunits OSCP (ATP5) and gamma (ATP3) alters leaf morphology, metabolism and gene expression in Arabidopsis.
ABSTRACT Determination of the role of mitochondrial (mt) ATP synthesis in plant metabolism is complicated by chloroplastic ATP synthesis. To differentiate ATP synthesis from these two organelles, we created transgenic Arabidopsis plants in which two different subunits of the mt ATP synthase, the oligomycin sensitivity-conferring protein (OSCP) (=delta) (ATP5) and the gamma (ATP3) subunit, were expressed individually in antisense orientation under the control of a dexamethasone-inducible promoter. The phenotypic effects of antisense expression were identical for both atp5 and atp3. Seedling lethality resulted from induction during germination in the light, demonstrating the essentiality of both gene products. Reduced expression of either gene resulted in stunting of dark-grown (etiolated) seedlings, downward curling or wavy-edged leaf margins of light-grown plants and ball-shaped unexpanded flowers. Antisense induction reduced total ATP levels in dark-grown (etiolated) seedlings germinated on media lacking sucrose, but increased total ATP levels in induced light-grown plants and in induced dark-grown seedlings germinated on media containing sucrose. Induction reduced transcript levels for two transcription factors (TCP3 and TCP4) whose decreased expression is associated with a similar wavy-edged leaf phenotype in Arabidopsis, and increased transcript levels for dynamin-related proteins whose increased expression is associated with increased mt division. Reduced expression of these subunits of the mt ATP synthase is proposed to disturb cellular redox states, which ultimately manifest downstream as diverse and seemingly unrelated phenotypes.
SourceAvailable from: Markus Wirtz[Show abstract] [Hide abstract]
ABSTRACT: The sulfur dioxygenase ETHE1 catalyzes the oxidation of persulfides in the mitochondrial matrix and is essential for early embryo development in Arabidopsis thaliana. We investigated the biochemical and physiological function of ETHE1 in plant metabolism using recombinant Arabidopsis ETHE1 and three T-DNA insertion lines with 50-99 % decreased sulfur dioxygenase activity. Our results identified a new mitochondrial pathway catalyzing the detoxification of reduced sulfur species derived from cysteine catabolism by oxidation to thiosulfate. Knockdown of the sulfur dioxygenase impaired embryo development and produced phenotypes of starvation-induced chlorosis during short-day growth condition and extended darkness, indicating that ETHE1 has a key function in situations of high protein turnover such as seed production and the use of amino acids as alternative respiratory substrates during carbohydrate starvation. The amino acid profile of mutant plants was similar to that caused by defects in the electron-transfer flavoprotein/electron-transfer flavoprotein:ubiquinone oxidoreductase complex and associated dehydrogenases. Thus, in addition to sulfur amino acid catabolism ETHE1 also affects the oxidation of branched-chain amino acids and lysine.Plant physiology 04/2014; 165(1). DOI:10.1104/pp.114.239764 · 7.39 Impact Factor
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ABSTRACT: Cytoplasmic male sterility (CMS) is a common feature encountered in plant species. It is the result of a genomic conflict between the mitochondrial and the nuclear genomes. CMS is caused by mitochondrial encoded factors which can be counteracted by nuclear encoded factors restoring male fertility. Despite extensive work, the molecular mechanism of male sterility still remains unknown. Several studies have suggested the involvement of respiration on the disruption of pollen production through an energy deficiency. By comparing recent works on CMS and respiratory mutants, we suggest that the "ATP hypothesis" might not be as obvious as previously suggested.Mitochondrion 04/2014; DOI:10.1016/j.mito.2014.04.009 · 3.52 Impact Factor
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ABSTRACT: Aims: ATP synthase uses chemiosmotic energy across the inner mitochondrial membrane to convert ADP and orthophosphate into ATP, while genetic deletion of Sirt3 decreases mitochondrial ATP levels. Herein, we investigate the mechanistic connection between SIRT3 and energy homeostasis. Results: By using both in vitro and in vivo experiments, we demonstrate that ATP synthase F1 proteins alpha, beta, gamma, and Oligomycin sensitivity-conferring protein (OSCP) contain SIRT3-specific reversible acetyl-lysines that are evolutionarily conserved and bind to SIRT3. OSCP was further investigated, and lysine 139 is a nutrient-sensitive, SIRT3-dependent deacetylation target. Site directed mutants demonstrate that OSCPK139 directs, at least in part, mitochondrial ATP production, and mice lacking Sirt3 exhibit decreased ATP muscle levels, increased ATP synthase protein acetylation, and an exercise-induced stress-deficient phenotype. Innovation: This work connects the aging and nutrient response, via SIRT3 direction of the mitochondrial acetylome, to the regulation of mitochondrial energy homeostasis under nutrient-stress conditions by deacetylating ATP synthase proteins. Conclusion: Our data suggest that acetylome signaling contributes to mitochondrial energy homeostasis by SIRT3 mediated deacetylation of ATP synthase proteins.Antioxidants & Redox Signaling 11/2013; DOI:10.1089/ars.2013.5420 · 8.20 Impact Factor