Alternative oxidase modulates leaf mitochondrial concentrations of superoxide and nitric oxide

Cvetkovska, Marina; Vanlerberghe, Greg C.

doi:10.1111/j.1469-8137.2012.04166.x

Cited by 147 publications

(145 citation statements)

References 45 publications

(54 reference statements)

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“…The development of a monoclonal antibody that recognized all AOX proteins studied to date (Elthon et al, 1989;Finnegan et al, 1999) facilitated the cloning of the gene, which allowed genetic approaches to be used to study AOX (Rhoads and McIntosh, 1991). Studies in tobacco (Nicotiana tabacum) with reduced or increased amounts of AOX (Vanlerberghe et al, 1994) showed that AOX suppresses the production of reactive oxygen species (ROS) in mitochondria (Maxwell et al, 1999;Cvetkovska and Vanlerberghe, 2012a, 2012b, 2013. Investigations with a variety of abiotic or biotic challenges revealed that AOX acts as a survival protein (Vanlerberghe et al, 2009), in that it allows plants to survive and grow better compared with plants that have reduced amounts of AOX.…”

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confidence: 99%

Decreasing Electron Flux through the Cytochrome and/or Alternative Respiratory Pathways Triggers Common and Distinct Cellular Responses Dependent on Growth Conditions

et al. 2014

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Diverse signaling pathways are activated by perturbation of mitochondrial function under different growth conditions. Mitochondria have emerged as an important organelle for sensing and coping with stress in addition to being the sites of important metabolic pathways. Here, responses to moderate light and drought stress were examined in different Arabidopsis (Arabidopsis thaliana) mutant plants lacking a functional alternative oxidase (alternative oxidase1a [aox1a]), those with reduced cytochrome electron transport chain capacity (T3/T7 bacteriophage-type RNA polymerase, mitochondrial, and plastidial [rpoTmp]), and double mutants impaired in both pathways (aox1a:rpoTmp). Under conditions considered optimal for growth, transcriptomes of aox1a and rpoTmp were distinct. Under adverse growth conditions, however, transcriptome changes in aox1a and rpoTmp displayed a highly significant overlap and were indicative of a common mitochondrial stress response and downregulation of photosynthesis. This suggests that the role of mitochondria to support photosynthesis is provided through either the alternative pathway or the cytochrome pathway, and when either pathway is inhibited, such as under environmental stress, a common, dramatic, and succinct mitochondrial signal is activated to alter energy metabolism in both organelles. aox1a:rpoTmp double mutants grown under optimal conditions showed dramatic reductions in biomass production compared with aox1a and rpoTmp and a transcriptome that was distinct from aox1a or rpoTmp. Transcript data indicating activation of mitochondrial biogenesis in aox1a:rpoTmp were supported by a proteomic analysis of over 200 proteins. Under optimal conditions, aox1a: rpoTmp plants seemed to switch on many of the typical mitochondrial stress regulators. Under adverse conditions, aox1a:rpoTmp turned off these responses and displayed a biotic stress response. Taken together, these results highlight the diverse signaling pathways activated by the perturbation of mitochondrial function under different growth conditions.

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confidence: 99%

Decreasing Electron Flux through the Cytochrome and/or Alternative Respiratory Pathways Triggers Common and Distinct Cellular Responses Dependent on Growth Conditions

et al. 2014

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“…Five SOD activities could be visualized, which, based upon their inhibitor sensitivities (see "Materials and Methods"; Cvetkovska and Vanlerberghe, 2012), included one manganese SOD (MnSOD), two iron SODs (FeSODs), and two copper zinc SODs (CuZnSODs). For each of the FeSODs and CuZnSODs, there was one major band of activity (which we termed FeSOD1 and CuZnSOD1) and one minor band of activity (termed FeSOD2 and CuZnSOD2).…”

Section: Resultsmentioning

confidence: 99%

“…In-gel SOD activity assays were done as previously described (Cvetkovska and Vanlerberghe, 2012). Protein carbonyl content was estimated by immunoblotting using the OxyBlot protein oxidation detection kit, following the manufacturer's instructions (EMD Millipore).…”

Section: Other Methodsmentioning

confidence: 99%

Mitochondrial Alternative Oxidase Maintains Respiration and Preserves Photosynthetic Capacity during Moderate Drought in Nicotiana tabacum

et al. 2014

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The mitochondrial electron transport chain includes an alternative oxidase (AOX) that is hypothesized to aid photosynthetic metabolism, perhaps by acting as an additional electron sink for photogenerated reductant or by dampening the generation of reactive oxygen species. Gas exchange, chlorophyll fluorescence, photosystem I (PSI) absorbance, and biochemical and protein analyses were used to compare respiration and photosynthesis of Nicotiana tabacum 'Petit Havana SR1' wild-type plants with that of transgenic AOX knockdown (RNA interference) and overexpression lines, under both well-watered and moderate droughtstressed conditions. During drought, AOX knockdown lines displayed a lower rate of respiration in the light than the wild type, as confirmed by two independent methods. Furthermore, CO 2 and light response curves indicated a nonstomatal limitation of photosynthesis in the knockdowns during drought, relative to the wild type. Also relative to the wild type, the knockdowns under drought maintained PSI and PSII in a more reduced redox state, showed greater regulated nonphotochemical energy quenching by PSII, and displayed a higher relative rate of cyclic electron transport around PSI. The origin of these differences may lie in the chloroplast ATP synthase amount, which declined dramatically in the knockdowns in response to drought. None of these effects were seen in plants overexpressing AOX. The results show that AOX is necessary to maintain mitochondrial respiration during moderate drought. In its absence, respiration rate slows and the lack of this electron sink feeds back on the photosynthetic apparatus, resulting in a loss of chloroplast ATP synthase that then limits photosynthetic capacity.

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“…6,9 On the other hand plant hormone salicylic acid concentration also shows dramatic effect toward AOX expression as low concentration induces AOX whereas higher concentration do not. 10,11 Biochemical control of AOX activity Expression of the AOX genes and protein formation do not determine the activity of the enzyme. AOX are inner mitochondrial membrane protein existing as a homodimer, regulated by 2 step biochemical regulation.…”

Section: Genetic Control Of Aox Respirationmentioning

confidence: 99%

Alternative oxidase and plant stress tolerance

Saha

Боровский

Panda

2016

Plant Signaling & Behavior

137

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Alternative oxidase (AOX) is one of the terminal oxidases of the plant mitochondrial electron transport chain. AOX acts as a means to relax the highly coupled and tensed electron transport process in mitochondria thus providing and maintaining the much needed metabolic homeostasis by directly reducing oxygen to water. In the process AOX also act as facilitator for signaling molecules conveying the metabolic status of mitochondria to the nucleus and thus able to influence nuclear gene expression. Since AOX indirectly, is able to control the synthesis of important signaling molecules like hydrogen peroxide, superoxide, nitric oxide, thus it is also helping in stress signaling. AOX mediated signaling and metabolic activities are very much important for plant stress response. This include both biotic (fungal, bacterial, viral, etc.) and abiotic (drought, salinity, cold, heavy metal, etc.) stresses. The review provides a gist of regulation and functioning of AOX. Plants being sessile, are exposed to various environmental stressors, viz, drought, salinity, metal toxicity, low or high temperature, pathogen attack, nutrient deficiency, hypoxia etc; which aims to hamper their lifestyle and lifespan to a great extent. So, it has developed certain inbuilt mechanism for perception of minute changes in the environment and responders which facilitates, either tolerance or avoidance responses to alleviate the stress. This review rotates round one of these molecules which helps in stress perception and mediates a retrograde signaling pathway to architect a tolerance/avoidance response. What is Alternative Oxidase?The discovery of alternative oxidase (AOX) was at the beginning of the 20 th century from thermogenic plants during anthesis. AOXs are interfacial membrane bound, cyanide insensitive, metallo-protein involved in mitochondrial redox reactions. AOX branches off from the cytochrome pathway of mitochondria at the level of Ubiquinone (UQ) and is responsible for coupling, oxidation of ubiquinol, to 4 electron reduction of oxygen to water.1 As AOX bypasses Complex III and IV of the cytochrome pathway, it dramatically reduces ATP generation and the energy thus released is dissipated as heat.2 It helps in maintaining metabolic homeostasis and signaling dynamics in mitochondria. Stressors effect plant growth resulting in misbalance of energy demands and production. The ability of plants to maintain the delicate balance of energy production and utilization is fundamentally important for their survival. Presence of AOX forms the striking functional difference between mitochondria of higher plants (as well as some fungi and protists) and animals, i.e., presence of two terminal oxidases, AOX and cytochrome oxidase. AOX is encoded by two nuclear gene subfamily, AOX1 and AOX2, where dicotyledons possesses both gene ubfamilies, while monocots have only AOX1 genes.3 AOX is responsible for thermogenesis (attract insects for pollination) and stress tolerance. In response to stress AOX mediates a retrograde signaling pathway which...

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Alternative oxidase modulates leaf mitochondrial concentrations of superoxide and nitric oxide

Cited by 147 publications

References 45 publications

Decreasing Electron Flux through the Cytochrome and/or Alternative Respiratory Pathways Triggers Common and Distinct Cellular Responses Dependent on Growth Conditions

Decreasing Electron Flux through the Cytochrome and/or Alternative Respiratory Pathways Triggers Common and Distinct Cellular Responses Dependent on Growth Conditions

Mitochondrial Alternative Oxidase Maintains Respiration and Preserves Photosynthetic Capacity during Moderate Drought in Nicotiana tabacum

Alternative oxidase and plant stress tolerance

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