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Analin B, Mohanan A, Bakka K, Challabathula D. Cytochrome oxidase and alternative oxidase pathways of mitochondrial electron transport chain are important for the photosynthetic performance of pea plants under salinity stress conditions. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2020; 154:248-259. [PMID: 32570012 DOI: 10.1016/j.plaphy.2020.05.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 05/20/2020] [Accepted: 05/20/2020] [Indexed: 06/11/2023]
Abstract
The flexible plant mitochondrial electron transport chain with cytochrome c oxidase (COX) and alternative oxidase (AOX) pathways is known to be modulated by abiotic stress conditions. The effect of salinity stress on the mitochondrial electron transport chain and the importance of COX and AOX pathways for optimization of photosynthesis under salinity stress conditions is not clearly understood. In the current study, importance of COX and AOX pathways for photosynthetic performance of pea plants (Pisum sativum L. Pea Arkel cv) was analysed by using the mitochondrial electron transport chain inhibitors Antimycin A (AA) and salicylhydroxamic acid (SHAM) which restrict the electron flow through COX and AOX pathways respectively. Salinity stress resulted in decreased CO2 assimilation rates, leaf stomatal conductance, transpiration and leaf intercellular CO2 concentration in a stress dependent manner. Superimposition of leaves of salt stressed plants with AA and SHAM caused cellular H2O2 and O2- accumulation along with cell death. Additionally, aggravation in decrease of CO2 assimilation rates, leaf stomatal conductance, transpiration and leaf intercellular CO2 concentration upon superimposition with AA and SHAM during salinity stress suggests the importance of mitochondrial oxidative electron transport for photosynthesis. Increased expression of AOX1a and AOX2 transcripts along with AOX protein levels indicated up regulation of AOX pathway in leaves during salinity stress. Chlorophyll fluorescence measurements revealed enhanced damage to Photosystem (PS) II in the presence of AA and SHAM during salinity stress. Results suggested the beneficial role of COX and AOX pathways for optimal photosynthetic performance in pea leaves during salinity stress conditions.
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Affiliation(s)
- Benedict Analin
- Plant Molecular Stress Physiology Research Group, Department of Life Sciences, School of Life Sciences, Central University of Tamil Nadu, Thiruvarur, 610 005, India
| | - Akhil Mohanan
- Plant Molecular Stress Physiology Research Group, Department of Life Sciences, School of Life Sciences, Central University of Tamil Nadu, Thiruvarur, 610 005, India
| | - Kavya Bakka
- Plant Molecular Stress Physiology Research Group, Department of Life Sciences, School of Life Sciences, Central University of Tamil Nadu, Thiruvarur, 610 005, India
| | - Dinakar Challabathula
- Plant Molecular Stress Physiology Research Group, Department of Life Sciences, School of Life Sciences, Central University of Tamil Nadu, Thiruvarur, 610 005, India.
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2
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He L, Li B, Lu X, Yuan L, Yang Y, Yuan Y, Du J, Guo S. The effect of exogenous calcium on mitochondria, respiratory metabolism enzymes and ion transport in cucumber roots under hypoxia. Sci Rep 2015; 5:11391. [PMID: 26304855 PMCID: PMC4548228 DOI: 10.1038/srep11391] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 04/29/2015] [Indexed: 11/20/2022] Open
Abstract
Hypoxia induces plant stress, particularly in cucumber plants under hydroponic culture. In plants, calcium is involved in stress signal transmission and growth. The ultimate goal of this study was to shed light on the mechanisms underlying the effects of exogenous calcium on the mitochondrial antioxidant system, the activity of respiratory metabolism enzymes, and ion transport in cucumber (Cucumis sativus L. cv. Jinchun No. 2) roots under hypoxic conditions. Our experiments revealed that exogenous calcium reduces the level of reactive oxygen species (ROS) and increases the activity of antioxidant enzymes in mitochondria under hypoxia. Exogenous calcium also enhances the accumulation of enzymes involved in glycolysis and the tricarboxylic acid (TCA) cycle. We utilized fluorescence and ultrastructural cytochemistry methods to observe that exogenous calcium increases the concentrations of Ca(2+) and K(+) in root cells by increasing the activity of plasma membrane (PM) H(+)-ATPase and tonoplast H(+)-ATPase and H(+)-PPase. Overall, our results suggest that hypoxic stress has an immediate and substantial effect on roots. Exogenous calcium improves metabolism and ion transport in cucumber roots, thereby increasing hypoxia tolerance in cucumber.
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Affiliation(s)
- Lizhong He
- Key Laboratory of Southern Vegetable Crop Genetic Improvement in Ministry of Agriculture, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
- Horticulture Research Institute, Shanghai Academy Agricultural Sciences, Key Laboratory of Protected Horticulture Technology, Shanghai, 201403, China
| | - Bin Li
- Key Laboratory of Southern Vegetable Crop Genetic Improvement in Ministry of Agriculture, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Xiaomin Lu
- Key Laboratory of Southern Vegetable Crop Genetic Improvement in Ministry of Agriculture, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
- College of Life Science, Anhui Science and Technology University, Fengyang, Anhui 233100, China
| | - Lingyun Yuan
- Key Laboratory of Southern Vegetable Crop Genetic Improvement in Ministry of Agriculture, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Yanjuan Yang
- Key Laboratory of Southern Vegetable Crop Genetic Improvement in Ministry of Agriculture, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Yinghui Yuan
- Key Laboratory of Southern Vegetable Crop Genetic Improvement in Ministry of Agriculture, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Jing Du
- Key Laboratory of Southern Vegetable Crop Genetic Improvement in Ministry of Agriculture, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Shirong Guo
- Key Laboratory of Southern Vegetable Crop Genetic Improvement in Ministry of Agriculture, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
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Nie S, Yue H, Zhou J, Xing D. Mitochondrial-derived reactive oxygen species play a vital role in the salicylic acid signaling pathway in Arabidopsis thaliana. PLoS One 2015; 10:e0119853. [PMID: 25811367 PMCID: PMC4374720 DOI: 10.1371/journal.pone.0119853] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 01/16/2015] [Indexed: 12/14/2022] Open
Abstract
Plant mitochondria constitute a major source of ROS and are proposed to act as signaling organelles in the orchestration of defense response. At present, the signals generated and then integrated by mitochondria are still limited. Here, fluorescence techniques were used to monitor the events of mitochondria in vivo, as well as the induction of mitochondrial signaling by a natural defensive signal chemical salicylic acid (SA). An inhibition of respiration was observed in isolated mitochondria subjected to SA. The cytochrome reductase activity analysis in isolated mitochondria demonstrated that SA might act directly on the complex III in the respiration chain by inhibiting the activity. With this alteration, a quick burst of mitochondrial ROS (mtROS) was stimulated. SA-induced mtROS caused mitochondrial morphology transition in leaf tissue or protoplasts expressing mitochondria-GFP (43C5) and depolarization of membrane potential. However, the application of AsA, an H2O2 scavenger, significantly prevented both events, indicating that both of them are attributable to ROS accumulation. In parallel, SA-induced mtROS up-regulated AOX1a transcript abundance and this induction was correlated with the disease resistance, whereas AsA-pretreatment interdicted this effect. It is concluded that mitochondria play an essential role in the signaling pathway of SA-induced ROS generation, which possibly provided new insight into the SA-mediated biological processes, including plant defense response.
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Affiliation(s)
- Shengjun Nie
- MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, China
| | - Haiyun Yue
- MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, China
| | - Jun Zhou
- MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, China
| | - Da Xing
- MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, China
- * E-mail:
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4
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McDonald AE. Alternative oxidase: what information can protein sequence comparisons give us? PHYSIOLOGIA PLANTARUM 2009; 137:328-341. [PMID: 19493309 DOI: 10.1111/j.1399-3054.2009.01242.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The finding that alternative oxidase (AOX) is present in most kingdoms of life has resulted in a large number of AOX sequences that are available for analyses. Multiple sequence alignments of AOX proteins from evolutionarily divergent organisms represent a valuable tool and can be used to identify amino acids and domains that may play a role in catalysis, membrane association and post-translational regulation, especially when these data are coupled with the structural model for the enzyme. I validate the use of this approach by demonstrating that it detects the conserved glutamate and histidine residues in AOX that initially led to its identification as a di-iron carboxylate protein and the generation of a structural model for the protein. A comparative analysis using a larger dataset identified 35 additional amino acids that are conserved in all AOXs examined, 30 of which have not been investigated to date. I hypothesize that these residues will be involved in the quinol terminal oxidase activity or membrane association of AOX. Major differences in AOX protein sequences between kingdoms are revealed, and it is hypothesized that two angiosperm-specific domains may be responsible for the non-covalent dimerization of AOX, whereas two indels in the aplastidic AOXs may play a role in their post-translational regulation. A scheme for predicting whether a particular AOX protein will be recognized by the alternative oxidase monoclonal antibody generated against the AOX of Sauromatum guttatum (Voodoo lily) is presented. The number of functional sites in AOX is greater than expected, and determining the structure of AOX will prove extremely valuable to future research.
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Affiliation(s)
- Allison E McDonald
- Department of Biology, The University of Western Ontario, 1151 Richmond St. N., London, Ontario N6A5B7, Canada.
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Yang JH, Zhang MF, Yu JQ. Relationship between cytoplasmic male sterility and SPL-like gene expression in stem mustard. PHYSIOLOGIA PLANTARUM 2008; 133:426-434. [PMID: 18331407 DOI: 10.1111/j.1399-3054.2008.01064.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We studied how mitochondria-nuclear interactions may give rise to cytoplasmic male sterility (CMS) in stem mustard exhibiting abnormal microsporogenesis. In this system, expression of SPL-like, the counterpart of the Arabidopsis nuclear gene SPOROCYTELESS, is specifically lost in buds of CMS plants. When mitochondrial-specific inhibitors were applied to wild-type fertile stem mustard plants, expression of SPL-like was repressed to some extent. As a consequence, the shape and vigor of pollen grains were severely affected, whereas the fertility of pistils remained unaltered. Thereby, we suggest that a probable pathway responsible for CMS in stem mustard involves mitochondrial retrograde regulation, with SPL-like as a target nuclear gene for a mitochondrial signal.
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Affiliation(s)
- Jing-Hua Yang
- Laboratory of Genetic Resources & Functional Improvement for Horticultural Plants, Department of Horticulture, Zhejiang University, Hangzhou 310029, China
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6
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Kotiaho M, Aittamaa M, Andersson M, Mikkola R, Valkonen J, Salkinoja-Salonen M. Antimycin A-producing nonphytopathogenic Streptomyces turgidiscabies from potato. J Appl Microbiol 2008; 104:1332-40. [DOI: 10.1111/j.1365-2672.2007.03661.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Mizuno N, Sugie A, Kobayashi F, Takumi S. Mitochondrial alternative pathway is associated with development of freezing tolerance in common wheat. JOURNAL OF PLANT PHYSIOLOGY 2008; 165:462-7. [PMID: 17766003 DOI: 10.1016/j.jplph.2007.04.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Revised: 04/29/2007] [Accepted: 04/30/2007] [Indexed: 05/17/2023]
Abstract
Cold acclimation is an adaptive process for acquiring cold/freezing tolerance in wheat. To clarify the cultivar difference of freezing tolerance, we compared mitochondrial respiration activity and the expression profile of alternative oxidase (AOX) genes under low-temperature conditions using two common wheat cultivars differing in freezing tolerance. During cold acclimation, the respiration capacity of the alternative pathway significantly increased in a freezing-tolerant cultivar compared with a freezing-sensitive cultivar. More abundant accumulation of the AOX and uncoupling protein gene transcripts was also observed under the low-temperature conditions in the tolerant cultivar than in the sensitive cultivar. These results suggest that the mitochondrial alternative pathway might be partly associated with the cold acclimation and freezing tolerance in wheat.
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Affiliation(s)
- Nobuyuki Mizuno
- Laboratory of Plant Genetics, Graduate School of Agricultural Science, Kobe University, Nada-ku, Kobe, Japan
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8
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Sugie A, Murai K, Takumi S. Alteration of respiration capacity and transcript accumulation level of alternative oxidase genes in necrosis lines of common wheat. Genes Genet Syst 2007; 82:231-9. [PMID: 17660693 DOI: 10.1266/ggs.82.231] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Mitochondrial alternative oxidase (AOX) is the terminal oxidase responsible for cyanide-insensitive and salicylhydroxamic acid-sensitive respiration in plants. AOX is a key enzyme of the alternative respiration pathway. To study the effects of necrotic cell death on the mitochondrial function, production of reactive oxygen species (ROS), respiration capacities and accumulation patterns of mitochondria-targeted protein-encoding gene transcripts were compared between wild-type, lesion-mimic mutant and hybrid necrosis wheat plants. Around cells with the necrosis symptom, ROS accumulated abundantly in the intercellular spaces. The ratio of the alternative pathway to the cytochrome pathway was markedly enhanced in the necrotic leaves. Transcripts of a wheat AOX gene, Waox1a, were more abundant in a novel lesion-mimic mutant of common wheat than in the wild-type plants. An increased level of the Waox1a transcripts was also observed in hybrid plants containing Ne1 and Ne2 genes. These results indicated that an increase of the wheat AOX transcript level resulted in enhancement of respiration capacity of the alternative pathway in the necrotic cells.
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Affiliation(s)
- Atsushi Sugie
- Laboratory of Plant Genetics, Faculty of Agriculture, and Graduate School of Science and Technology, Kobe University, Nada-ku, Kobe, Japan
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9
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Castro-Guerrero NA, Rodríguez-Zavala JS, Marín-Hernández A, Rodríguez-Enríquez S, Moreno-Sánchez R. Enhanced alternative oxidase and antioxidant enzymes under Cd2+ stress in Euglena. J Bioenerg Biomembr 2007; 40:227-35. [PMID: 17899336 DOI: 10.1007/s10863-007-9098-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2007] [Accepted: 08/22/2007] [Indexed: 11/26/2022]
Abstract
To identify some of the mechanisms involved in the high resistance to Cd(2+) in the protist Euglena gracilis, we studied the effect of Cd(2+) exposure on its energy and oxidative stress metabolism as well as on essential heavy metals homeostasis. In E. gracilis heterotrophic cells, as in other organisms, CdCl(2) (50 microM) induced diminution in cell growth, severe oxidative stress accompanied by increased antioxidant enzyme activity and strong perturbation of the heavy metal homeostasis. However, Cd(2+) exposure did not substantially modify the cellular respiratory rate or ATP intracellular level, although the activities of respiratory complexes III and IV were strongly decreased. In contrast, an enhanced capacity of the alternative oxidase (AOX) in both intact cells and isolated mitochondria was determined under Cd(2+) stress; in fact, AOX activity accounted for 69-91% of total respiration. Western blotting also revealed an increased AOX content in mitochondria from Cd(2+)-exposed cells. Moreover, AOX was more resistant to Cd(2+) inhibition than cytochrome c oxidase in mitochondria from control and Cd(2+)-exposed cells. Therefore, an enhanced AOX seems to be a relevant component of the resistance mechanism developed by E. gracilis against Cd(2+)-stress, in addition to the usual increased antioxidant enzyme activity, that enabled cells to maintain a relatively unaltered the energy status.
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10
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Sugie A, Naydenov N, Mizuno N, Nakamura C, Takumi S. Overexpression of wheat alternative oxidase gene Waox1a alters respiration capacity and response to reactive oxygen species under low temperature in transgenic Arabidopsis. Genes Genet Syst 2006; 81:349-54. [PMID: 17159296 DOI: 10.1266/ggs.81.349] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Under low temperature conditions, the cytochrome pathway of respiration is repressed and reactive oxygen species (ROS) are produced in plants. Mitochondrial alternative oxidase (AOX) is the terminal oxidase responsible for the cyanide-insensitive and salicylhydroxamic acid-sensitive respiration. To study functions of wheat AOX genes under low temperature, we produced transgenic Arabidopsis by introducing Waox1a expressed under control of the cauliflower mosaic virus (CaMV) 35S promoter in Arabidopsis thaliana. The enhancement of endogenous AOX1a expression via low temperature stress was delayed in the transgenic Arabidopsis. Recovery of the total respiration activity under low temperature occurred more rapidly in the transgenic plants than in the wild-type plants due to a constitutively increased alternative pathway capacity. Levels of ROS decreased in the transgenic plants under low temperature stress. These results support the hypothesis that AOX alleviates oxidative stress when the cytochrome pathway of respiration is inhibited under abiotic stress conditions.
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Affiliation(s)
- Atsushi Sugie
- Laboratory of Plant Genetics, Faculty of Agriculture, and Graduate School of Science and Technology, Kobe University, Kobe, Japan
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11
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Borecký J, Vercesi AE. Plant Uncoupling Mitochondrial Protein and Alternative Oxidase: Energy Metabolism and Stress. Biosci Rep 2005; 25:271-86. [PMID: 16283557 DOI: 10.1007/s10540-005-2889-2] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Energy-dissipation in plant mitochondria can be mediated by inner membrane proteins via two processes: redox potential-dissipation or proton electrochemical potential-dissipation. Alternative oxidases (AOx) and the plant uncoupling mitochondrial proteins (PUMP) perform a type of intrinsic and extrinsic regulation of the coupling between respiration and phosphorylation, respectively. Expression analyses and functional studies on AOx and PUMP under normal and stress conditions suggest that the physiological role of both systems lies most likely in tuning up the mitochondrial energy metabolism in response of cells to stress situations. Indeed, the expression and function of these proteins in non-thermogenic tissues suggest that their primary functions are not related to heat production.
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Affiliation(s)
- Jirí Borecký
- Departamento de Patologia Clínica (NMCE), FCM, Universidade Estadual de Campinas (UNICAMP), CP 6111, 13083-970 Campinas, SP, Brazil
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Geisler DA, Johansson FI, Svensson ÅS, Rasmusson AG. Antimycin A treatment decreases respiratory internal rotenone-insensitive NADH oxidation capacity in potato leaves. BMC PLANT BIOLOGY 2004; 4:8. [PMID: 15140267 PMCID: PMC424582 DOI: 10.1186/1471-2229-4-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2003] [Accepted: 05/12/2004] [Indexed: 05/20/2023]
Abstract
BACKGROUND The plant respiratory chain contains several energy-dissipating enzymes, these being type II NAD(P)H dehydrogenases and the alternative oxidase, not present in mammals. The physiological functions of type II NAD(P)H dehydrogenases are largely unclear and little is known about their responses to stress. In this investigation, potato plants (Solanum tuberosum L., cv. Desiree) were sprayed with antimycin A, an inhibitor of the cytochrome pathway. Enzyme capacities of NAD(P)H dehydrogenases (EC 1.6.5.3) and the alternative oxidase were then analysed in isolated leaf mitochondria. RESULTS We report a specific decrease in internal rotenone-insensitive NADH dehydrogenase capacity in mitochondria from antimycin A-treated leaves. External NADPH dehydrogenase and alternative oxidase capacities remained unaffected by the treatment. Western blotting revealed no change in protein abundance for two characterised NAD(P)H dehydrogenase homologues, NDA1 and NDB1, nor for two subunits of complex I. The alternative oxidase was at most only slightly increased. Transcript levels of nda1, as well as an expressed sequence tag derived from a previously uninvestigated closely related potato homologue, remained unchanged by the treatment. As compared to the daily rhythm-regulated nda1, the novel homologue displayed steady transcript levels over the time investigated. CONCLUSIONS The internal rotenone-insensitive NADH oxidation decreases after antimycin A treatment of potato leaves. However, the decrease is not due to changes in expression of known nda genes. One consequence of the lower NADH dehydrogenase capacity may be a stabilisation of the respiratory chain reduction level, should the overall capacity of the cytochrome and the alternative pathway be restricted.
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Affiliation(s)
- Daniela A Geisler
- Dept of Cell and Organism Biology, Lund University, Sölvegatan 35B, Lund, (SE-223 62), Sweden
| | - Fredrik I Johansson
- Dept of Cell and Organism Biology, Lund University, Sölvegatan 35B, Lund, (SE-223 62), Sweden
| | - Å Staffan Svensson
- Dept of Cell and Organism Biology, Lund University, Sölvegatan 35B, Lund, (SE-223 62), Sweden
- Dept of Plant Biology, The Royal Veterinary and Agricultural University, Thorvaldsensvej 40, Frederiksberg C, (DK-1871), Denmark
| | - Allan G Rasmusson
- Dept of Cell and Organism Biology, Lund University, Sölvegatan 35B, Lund, (SE-223 62), Sweden
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Norman C, Howell KA, Millar AH, Whelan JM, Day DA. Salicylic acid is an uncoupler and inhibitor of mitochondrial electron transport. PLANT PHYSIOLOGY 2004; 134:492-501. [PMID: 14684840 PMCID: PMC316328 DOI: 10.1104/pp.103.031039] [Citation(s) in RCA: 154] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2003] [Revised: 09/05/2003] [Accepted: 10/17/2003] [Indexed: 05/18/2023]
Abstract
The effect of salicylic acid (SA) on respiration and mitochondrial function was examined in tobacco (Nicotiana tabacum) suspension cell cultures in the range of 0.01 to 5 mm. Cells rapidly accumulated SA up to 10-fold of the externally applied concentrations. At the lower concentrations, SA accumulation was transitory. When applied at 0.1 mm or less, SA stimulated respiration of whole cells and isolated mitochondria in the absence of added ADP, indicating uncoupling of respiration. However, at higher concentrations, respiration was severely inhibited. Measurements of ubiquinone redox poise in isolated mitochondria suggested that SA blocked electron flow from the substrate dehydrogenases to the ubiquinone pool. This inhibition could be at least partially reversed by re-isolating the mitochondria. Two active analogs of SA, benzoic acid and acetyl-SA, had the same effect as SA on isolated tobacco mitochondria, whereas the inactive p-hydroxybenzoic acid was without effect at the same concentration. SA induced an increase in Aox protein levels in cell suspensions, and this was correlated with an increase in Aox1 transcript abundance. However, when applied at 0.1 mM, this induction was transient and disappeared as SA levels in the cells declined. SA at 0.1 mM also increased the expression of other SA-responsive genes, and this induction was dependent on active mitochondria. The results indicate that SA is both an uncoupler and an inhibitor of mitochondrial electron transport and suggest that this underlies the induction of some genes by SA. The possible implications of this for the interpretation of SA action in plants are discussed.
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Affiliation(s)
- Christel Norman
- Plant Molecular Biology Group, Biochemistry and Molecular Biology, School of Biomedical and Chemical Sciences, Faculty of Natural and Agricultural Sciences, The University of Western Australia, Crawley 6009, Western Australia, Australia
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Alternative oxidase present in procyclic Trypanosoma brucei may act to lower the mitochondrial production of superoxide. Arch Biochem Biophys 2003; 414:294-302. [PMID: 12781782 DOI: 10.1016/s0003-9861(03)00196-6] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The mitochondrial electron transfer chain present in the procyclic form of the African trypanosome Trypanosoma brucei contains both cytochrome c oxidase and an alternative oxidase (TAO) as terminal oxidases that reduce oxygen to water. By contrast, the electron transfer chain of the primitive mitochondrion present in the bloodstream form of T. brucei contains only TAO as the terminal oxidase. TAO functions in the bloodstream forms to oxidize the ubiquinol produced by the glycerol-3-phosphate shuttle that results in the oxidation of the reduced nicotinamide adenine dinucleotide phosphate produced by glycolysis. The function, however, of TAO in the procyclic forms is unknown. In this study, we found that inhibition of TAO by the specific inhibitor salicylhydroxamic acid stimulates the formation of reactive oxygen species (ROS) in trypanosome mitochondria, resulting in mitochondrial alteration and increased oxidation of cellular proteins. Moreover, the activity and protein content of TAO in procyclic trypanosomes were increased when cells were incubated in the presence of hydrogen peroxide or antimycin A, the cytochrome bc1 complex inhibitor, which also results in increased ROS production. We suggest that one function of TAO in procyclic cells may be to prevent ROS production by removing excess reducing equivalents and transferring them to oxygen.
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Baurain D, Dinant M, Coosemans N, Matagne RF. Regulation of the alternative oxidase Aox1 gene in Chlamydomonas reinhardtii. Role of the nitrogen source on the expression of a reporter gene under the control of the Aox1 promoter. PLANT PHYSIOLOGY 2003; 131:1418-30. [PMID: 12644691 PMCID: PMC166901 DOI: 10.1104/pp.013409] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2002] [Revised: 11/03/2002] [Accepted: 12/10/2002] [Indexed: 05/21/2023]
Abstract
In higher plants, various developmental and environmental conditions enhance expression of the alternative oxidase (AOX), whereas its induction in fungi is mainly dependent on cytochrome pathway restriction and triggering by reactive oxygen species. The AOX of the unicellular green alga Chlamydomonas reinhardtii is encoded by two different genes, the Aox1 gene being much more transcribed than Aox2. To analyze the transcriptional regulation of Aox1, we have fused its 1.4-kb promoter region to the promoterless arylsulfatase (Ars) reporter gene and measured ARS enzyme activities in transformants carrying the chimeric construct. We show that the Aox1 promoter is generally unresponsive to a number of known AOX inducers, including stress agents, respiratory inhibitors, and metabolites, possibly because the AOX activity is constitutively high in the alga. In contrast, the Aox1 expression is strongly dependent on the nitrogen source, being down-regulated by ammonium and stimulated by nitrate. Inactivation of nitrate reductase leads to a further increase of expression. The stimulation by nitrate also occurs at the AOX protein and respiratory levels. A deletion analysis of the Aox1 promoter region demonstrates that a short upstream segment (-253 to +59 with respect to the transcription start site) is sufficient to ensure gene expression and regulation, but that distal elements are required for full gene expression. The observed pattern of AOX regulation points to the possible interaction between chloroplast and mitochondria in relation to a potential increase of photogenerated ATP when nitrate is used as a nitrogen source.
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Affiliation(s)
- Denis Baurain
- Genetics of Microorganisms, Department of Life Sciences, B22, University of Liège, Sart Tilman, B-4000 Liège, Belgium
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16
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Ordog SH, Higgins VJ, Vanlerberghe GC. Mitochondrial alternative oxidase is not a critical component of plant viral resistance but may play a role in the hypersensitive response. PLANT PHYSIOLOGY 2002; 129:1858-65. [PMID: 12177499 PMCID: PMC166774 DOI: 10.1104/pp.003855] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2002] [Revised: 04/11/2002] [Accepted: 04/20/2002] [Indexed: 05/17/2023]
Abstract
Transgenic tobacco (Nicotiana tabacum) with altered levels of mitochondrial alternative oxidase (AOX) were used to examine the potential role of this electron transport chain protein in resistance to tobacco mosaic virus. We examined the effect of AOX expression on the salicylic acid-induced resistance in susceptible plants and the resistance responses of plants harboring the N-gene. A lack of AOX did not compromise the ability of salicylic acid treatment to heighten the resistance of susceptible plants. In plants with the N-gene, a lack of AOX did not compromise the ability of the hypersensitive response to restrict the virus or the ability of the plant to develop systemic acquired resistance. Overexpression of AOX did not heighten the resistance of susceptible plants, but did result in smaller hypersensitive response lesions, suggesting a link between mitochondrial function and this programmed cell death event. We conclude that AOX is not a critical component of the previously characterized salicylhydroxamic acid-sensitive pathway important in viral resistance.
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Affiliation(s)
- Sandi H Ordog
- Division of Life Sciences and Department of Botany, University of Toronto at Scarborough, Scarborough, Ontario, Canada M1C 1A4
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Vanlerberghe GC, Ordog SH. Alternative Oxidase: Integrating Carbon Metabolism and Electron Transport in Plant Respiration. ADVANCES IN PHOTOSYNTHESIS AND RESPIRATION 2002. [DOI: 10.1007/0-306-48138-3_11] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Juszczuk IM, Wagner AM, Rychter AM. Regulation of alternative oxidase activity during phosphate deficiency in bean roots (Phaseolus vulgaris). PHYSIOLOGIA PLANTARUM 2001; 113:185-192. [PMID: 12060295 DOI: 10.1034/j.1399-3054.2001.1130205.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Cyanide-resistant respiration was studied in mitochondria isolated from the roots of bean plants (Phaseolus vulgaris L. cv. Złota Saxa) grown hydroponically up to 16 days on a phosphate-sufficient (+P, control) or phosphate-deficient (-P) medium. Western blotting indicated that the alternative oxidase (AOX) was present only in its reduced (active) form, both in phosphate-sufficient and phosphate-deficient roots, but in the latter, the amount of AOX protein was greater. Addition of pyruvate to the isolation, washing and reaction media made mitochondria from +P roots cyanide-insensitive, similar to mitochondria from -P roots. The doubled activity of NAD-malic enzyme (NAD-ME) in -P compared with +P root mitochondria may suggest increased pyruvate production in -P mitochondria. Lower cytochrome c oxidase (COX) activity and no uncoupler effect on respiration indicated limited cytochrome chain activity in -P mitochondria. In -P mitochondria, the oxygen uptake decreased and the level of Q reduction increased from 60 to 80%. With no pyruvate present (AOX not fully activated), inhibition of the cytochrome pathway resulted in an increased level of the ratio of reduced ubiquinone (Qr) to total ubiquinone (Qt) (Qr/Qt) in +P mitochondria, but did not change Qr/Qt in -P mitochondria. When pyruvate was present, the kinetics for AOX were similar in mitochondria from -P and +P roots. It is suggested that AOX participation in -P respiration may provide an acclimation to phosphate deficiency. Stabilization of the ubiquinone reduction level by AOX might prevent the harmful effect of an increased formation of reactive oxygen species.
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Affiliation(s)
- Izabela M. Juszczuk
- Institute of Experimental Plant Biology, University of Warsaw, Miecznikowa 1, PL-02-096 Warsaw, Poland Department of Molecular Cell Physiology, Free University, De Boelelaan 1087, NL-1081 HV Amsterdam, The Netherlands
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Saish D, Nakazono M, Lee KH, Tsutsumi N, Akita S, Hirai A. The gene for alternative oxidase-2 (AOX2) from Arabidopsis thaliana consists of five exons unlike other AOX genes and is transcribed at an early stage during germination. Genes Genet Syst 2001; 76:89-97. [PMID: 11434463 DOI: 10.1266/ggs.76.89] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
We investigated the expressions of genes for alternative oxidase (AOX1a, AOX1b, AOX1c and AOX2) and genes for cytochrome c oxidase (COX5b and COX6b) during germination of Arabidopsis thaliana, and examined oxygen uptakes of the alternative respiration and the cytochrome respiration in imbibed Arabidopsis seeds. A Northern blot analysis showed that AOX2 mRNA has already accumulated in dry seeds and subsequently decreased, whereas accumulation ofAOX1a mRNA was less abundant from 0 hours to 48 hours after imbibition and then increased. The increase of the capacity of the alternative pathway appeared to be dependent on the expressions of both AOX2 and AOX1a. On the other hand, steady-state mRNA levels of COX5b and COX6b were gradually increased during germination, and the capacity of the cytochrome pathway was correlated with the increase of expressions of the COX genes. Antimycin A, the respiratory inhibitor, strongly increased the expression of AOX1a but had no effect on the expression of AOX2. A 5'RACE analysis showed that AOX2 consists of five exons, which is different from the case of most AOX genes identified so far. Analysis of subcellular localization of AOX2 using green fluorescent protein indicated that the AOX2 protein is imported into the mitochondria.
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Affiliation(s)
- D Saish
- Laboratory of Plant Molecular Genetics, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Japan
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Amora Y, Chevionb M, Levinea A. Anoxia pretreatment protects soybean cells against H(2)O(2)-induced cell death: possible involvement of peroxidases and of alternative oxidase. FEBS Lett 2000; 477:175-80. [PMID: 10908716 DOI: 10.1016/s0014-5793(00)01797-x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Anoxia followed by reoxygenation causes extensive damage to cellular components through generation of reactive oxygen intermediates. We examined cellular responses to oxidative stress after anoxia in cultured soybean or human fibroblast cells. Anoxia pretreatment protected soybean but not fibroblasts against H(2)O(2) concentrations that induced programmed cell death in normoxic cells. H(2)O(2) removal in anoxia-pretreated soybean cultures was faster. Protection was associated with increased action of alternative oxidase (AOX) and peroxidases. AOX inhibitors abolished the protective effect, while induction of AOX protected normoxic cells against H(2)O(2). We propose that during anoxia, plant cells can prepare for reoxygenation injury by up-regulating their antioxidant capacity, and that AOX is involved in this process.
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Affiliation(s)
- Y Amora
- Department of Plant Sciences, Hebrew University of Jerusalem, Jerusalem Givat-Ram 91904, Israel, USA
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Finnegan PM, Wooding AR, Day DA. An alternative oxidase monoclonal antibody recognises a highly conserved sequence among alternative oxidase subunits. FEBS Lett 1999; 447:21-4. [PMID: 10218574 DOI: 10.1016/s0014-5793(99)00259-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The alternative oxidase is found in the inner mitochondrial membranes of plants and some fungi and protists. A monoclonal antibody raised against the alternative oxidase from the aroid lily Sauromatum guttatum has been used extensively to detect the enzyme in these organisms. Using an immunoblotting strategy, the antibody binding site has been localised to the sequence RADEAHHRDVNH within the soybean alternative oxidase 2 protein. Examination of sequence variants showed that A2 and residues C-terminal to H7 are required for recognition by the monoclonal antibody raised against the alternative oxidase. The recognition sequence is highly conserved among all alternative oxidase proteins and is absolutely conserved in 12 of 14 higher plant sequences, suggesting that this antibody will continue to be extremely useful in studying the expression and synthesis of the alternative oxidase.
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Affiliation(s)
- P M Finnegan
- Division of Biochemistry and Molecular Biology, Faculty of Science, The Australian National University, Canberra, ACT.
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Millenaar FF, Benschop JJ, Wagner AM, Lambers H. The role of the alternative oxidase in stabilizing the in vivo reduction state of the ubiquinone pool and the activation state of the alternative oxidase. PLANT PHYSIOLOGY 1998; 118:599-607. [PMID: 9765546 PMCID: PMC34836 DOI: 10.1104/pp.118.2.599] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
A possible function for the alternative (nonphosphorylating) pathway is to stabilize the reduction state of the ubiquinone pool (Qr/Qt), thereby avoiding an increase in free radical production. If the Qr/Qt were stabilized by the alternative pathway, then Qr/Qt should be less stable when the alternative pathway is blocked. Qr/Qt increased when we exposed roots of Poa annua (L.) to increasing concentrations of KCN (an inhibitor of the cytochrome pathway). However, when salicylhydroxamic acid, an inhibitor of the alternative pathway, was added at the same time, Qr/Qt increased significantly more. Therefore, we conclude that the alternative pathway stabilizes Qr/Qt. Salicylhydroxamic acid increasingly inhibited respiration with increasing concentrations of KCN. In the experiments described here the alternative oxidase protein was invariably in its reduced (high-activity) state. Therefore, changes in the reduction state of the alternative oxidase cannot account for an increase in activity of the alternative pathway upon titration with KCN. The pyruvate concentration in intact roots increased only after the alternative pathway was blocked or the cytochrome pathway was severely inhibited. The significance of the pyruvate concentration and Qr/Qt on the activity of the alternative pathway in intact roots is discussed.
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Affiliation(s)
- FF Millenaar
- Department of Plant Ecology and Evolutionary Biology, Utrecht University Graduate School of Experimental Plant Science, Sorbonnelaan 16, 3584 CA Utrecht, The Netherlands (F.F.M., J.J.B., H. L.)
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Wagner, Wagner, Moore. In vivo ubiquinone reduction levels during thermogenesis in araceae. PLANT PHYSIOLOGY 1998; 117:1501-6. [PMID: 9701605 PMCID: PMC34913 DOI: 10.1104/pp.117.4.1501] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/1998] [Accepted: 05/15/1998] [Indexed: 05/18/2023]
Abstract
In vivo ubiquinone (UQ) reduction levels were measured during the development of the inflorescences of Arum maculatum and Amorphophallus krausei. Thermogenesis in A. maculatum spadices appeared not to be confined to a single developmental stage, but occurred during various stages. The UQ pool in both A. maculatum and A. krausei appendices was approximately 90% reduced during thermogenesis. Respiratory characteristics of isolated appendix mitochondria did not change in the period around thermogenesis. Apparently, synthesis of the required enzyme capacity is regulated via a coarse control upon which a fine control of metabolism that regulates the onset of thermogenesis is imposed.
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Affiliation(s)
- Wagner
- Department of Molecular Cell Physiology, Vrije Universiteit, De Boelelaan 1087, 1081 HV Amsterdam, The Netherlands (A.M.W., M.J.W.)
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