1
|
Sweetman C, Selinski J, Miller TK, Whelan J, Day DA. Legume Alternative Oxidase Isoforms Show Differential Sensitivity to Pyruvate Activation. FRONTIERS IN PLANT SCIENCE 2022; 12:813691. [PMID: 35111186 PMCID: PMC8801435 DOI: 10.3389/fpls.2021.813691] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 12/27/2021] [Indexed: 05/29/2023]
Abstract
Alternative oxidase (AOX) is an important component of the plant respiratory pathway, enabling a route for electrons that bypasses the energy-conserving, ROS-producing complexes of the mitochondrial electron transport chain. Plants contain numerous isoforms of AOX, classified as either AOX1 or AOX2. AOX1 isoforms have received the most attention due to their importance in stress responses across a wide range of species. However, the propensity for at least one isoform of AOX2 to accumulate to very high levels in photosynthetic tissues of all legumes studied to date, suggests that this isoform has specialized roles, but we know little of its properties. Previous studies with sub-mitochondrial particles of soybean cotyledons and roots indicated that differential expression of GmAOX1, GmAOX2A, and GmAOX2D across tissues might confer different activation kinetics with pyruvate. We have investigated this using recombinantly expressed isoforms of soybean AOX in a previously described bacterial system (Selinski et al., 2016, Physiologia Plantarum 157, 264-279). Pyruvate activation kinetics were similar between the two GmAOX2 isoforms but differed substantially from those of GmAOX1, suggesting that selective expression of AOX1 and 2 could determine the level of AOX activity. However, this alone cannot completely explain the differences seen in sub-mitochondrial particles isolated from different legume tissues and possible reasons for this are discussed.
Collapse
Affiliation(s)
- Crystal Sweetman
- College of Science and Engineering, Flinders University, Bedford Park, SA, Australia
| | - Jennifer Selinski
- Department of Plant Cell Biology, Botanical Institute, Christian-Albrecht University of Kiel, Kiel, Germany
| | - Troy K. Miller
- College of Science and Engineering, Flinders University, Bedford Park, SA, Australia
| | - James Whelan
- Department of Animal, Plant, and Soil Science, School of Soil Science, La Trobe University, Bundoora, VIC, Australia
| | - David A. Day
- College of Science and Engineering, Flinders University, Bedford Park, SA, Australia
| |
Collapse
|
2
|
Sankar TV, Saharay M, Santhosh D, Vishwakarma A, Padmasree K. Structural and Biophysical Characterization of Purified Recombinant Arabidopsis thaliana's Alternative Oxidase 1A (rAtAOX1A): Interaction With Inhibitor(s) and Activator. FRONTIERS IN PLANT SCIENCE 2022; 13:871208. [PMID: 35783971 PMCID: PMC9243770 DOI: 10.3389/fpls.2022.871208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 04/27/2022] [Indexed: 05/14/2023]
Abstract
In higher plants, alternative oxidase (AOX) participates in a cyanide resistant and non-proton motive electron transport pathway of mitochondria, diverging from the ubiquinone pool. The physiological significance of AOX in biotic/abiotic stress tolerance is well-documented. However, its structural and biophysical properties are poorly understood as its crystal structure is not yet revealed in plants. Also, most of the AOX purification processes resulted in a low yield/inactive/unstable form of native AOX protein. The present study aims to characterize the purified rAtAOX1A protein and its interaction with inhibitors, such as salicylhydroxamic acid (SHAM) and n-propyl gallate (n-PG), as well as pyruvate (activator), using biophysical/in silico studies. The rAtAOX1A expressed in E. coli BL21(DE3) cells was functionally characterized by monitoring the respiratory and growth sensitivity of E. coli/pAtAOX1A and E. coli/pET28a to classical mitochondrial electron transport chain (mETC) inhibitors. The rAtAOX1A, which is purified through affinity chromatography and confirmed by western blotting and MALDI-TOF-TOF studies, showed an oxygen uptake activity of 3.86 μmol min-1 mg-1 protein, which is acceptable in non-thermogenic plants. Circular dichroism (CD) studies of purified rAtAOX1A revealed that >50% of the protein content was α-helical and retained its helical absorbance signal (ellipticity) at a wide range of temperature and pH conditions. Further, interaction with SHAM, n-PG, or pyruvate caused significant changes in its secondary structural elements while retaining its ellipticity. Surface plasmon resonance (SPR) studies revealed that both SHAM and n-PG bind reversibly to rAtAOX1A, while docking studies revealed that they bind to the same hydrophobic groove (Met191, Val192, Met195, Leu196, Phe251, and Phe255), to which Duroquinone (DQ) bind in the AtAOX1A. In contrast, pyruvate binds to a pocket consisting of Cys II (Arg174, Tyr175, Gly176, Cys177, Val232, Ala233, Asn294, and Leu313). Further, the mutational docking studies suggest that (i) the Met195 and Phe255 of AtAOX1A are the potential candidates to bind the inhibitor. Hence, this binding pocket could be a 'potential gateway' for the oxidation-reduction process in AtAOX1A, and (ii) Arg174, Gly176, and Cys177 play an important role in binding to the organic acids like pyruvate.
Collapse
Affiliation(s)
- Tadiboina Veera Sankar
- Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Moumita Saharay
- Department of Systems and Computational Biology, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Dharawath Santhosh
- Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Abhaypratap Vishwakarma
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, India
- Department of Botany, Deshbandhu College, University of Delhi, New Delhi, India
| | - Kollipara Padmasree
- Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad, India
- *Correspondence: Kollipara Padmasree
| |
Collapse
|
3
|
Sweetman C, Soole KL, Jenkins CLD, Day DA. Genomic structure and expression of alternative oxidase genes in legumes. PLANT, CELL & ENVIRONMENT 2019; 42:71-84. [PMID: 29424926 DOI: 10.1111/pce.13161] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 01/22/2018] [Accepted: 01/25/2018] [Indexed: 05/26/2023]
Abstract
Mitochondria isolated from chickpea (Cicer arietinum) possess substantial alternative oxidase (AOX) activity, even in non-stressed plants, and one or two AOX protein bands were detected immunologically, depending on the organ. Four different AOX isoforms were identified in the chickpea genome: CaAOX1 and CaAOX2A, B and D. CaAOX2A was the most highly expressed form and was strongly expressed in photosynthetic tissues, whereas CaAOX2D was found in all organs examined. These results are very similar to those of previous studies with soybean and siratro. Searches of available databases showed that this pattern of AOX genes and their expression was common to at least 16 different legume species. The evolution of the legume AOX gene family is discussed, as is the in vivo impact of an inherently high AOX capacity in legumes on growth and responses to environmental stresses.
Collapse
Affiliation(s)
- Crystal Sweetman
- Australian Research Council Industrial Transformation Research Hub, Legumes for Sustainable Agriculture, College of Science and Engineering, Flinders University of South Australia, Adelaide, South Australia, GPO Box 2001, Australia
| | - Kathleen L Soole
- Australian Research Council Industrial Transformation Research Hub, Legumes for Sustainable Agriculture, College of Science and Engineering, Flinders University of South Australia, Adelaide, South Australia, GPO Box 2001, Australia
| | - Colin L D Jenkins
- Australian Research Council Industrial Transformation Research Hub, Legumes for Sustainable Agriculture, College of Science and Engineering, Flinders University of South Australia, Adelaide, South Australia, GPO Box 2001, Australia
| | - David A Day
- Australian Research Council Industrial Transformation Research Hub, Legumes for Sustainable Agriculture, College of Science and Engineering, Flinders University of South Australia, Adelaide, South Australia, GPO Box 2001, Australia
| |
Collapse
|
4
|
Selinski J, Scheibe R, Day DA, Whelan J. Alternative Oxidase Is Positive for Plant Performance. TRENDS IN PLANT SCIENCE 2018; 23:588-597. [PMID: 29665989 DOI: 10.1016/j.tplants.2018.03.012] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 03/15/2018] [Accepted: 03/22/2018] [Indexed: 05/02/2023]
Abstract
The alternative pathway of mitochondrial electron transport, which terminates in the alternative oxidase (AOX), uncouples oxidation of substrate from mitochondrial ATP production, yet plant performance is improved under adverse growth conditions. AOX is regulated at different levels. Identification of regulatory transcription factors shows that Arabidopsis thaliana AOX1a is under strong transcriptional suppression. At the protein level, the primary structure is not optimised for activity. Maximal activity requires the presence of various metabolites, such as tricarboxylic acid-cycle intermediates that act in an isoform-specific manner. In this opinion article we propose that the regulatory mechanisms that keep AOX activity suppressed, at both the gene and protein level, are positive for plant performance due to the flexible short- and long-term fine-tuning.
Collapse
Affiliation(s)
- Jennifer Selinski
- Department of Animal, Plant, and Soil Science, Australian Research Council Centre of Excellence in Plant Energy Biology, School of Life Science, La Trobe University Bundoora, VIC 3083, Australia.
| | - Renate Scheibe
- Division of Plant Physiology, Department of Biology/Chemistry, University of Osnabrueck, D-49069 Osnabrueck, Germany
| | - David A Day
- College of Science and Engineering, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia
| | - James Whelan
- Department of Animal, Plant, and Soil Science, Australian Research Council Centre of Excellence in Plant Energy Biology, School of Life Science, La Trobe University Bundoora, VIC 3083, Australia
| |
Collapse
|
5
|
Measurements of Electron Partitioning Between Cytochrome and Alternative Oxidase Pathways in Plant Tissues. Methods Mol Biol 2018; 1670:203-217. [PMID: 28871545 DOI: 10.1007/978-1-4939-7292-0_17] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Abstract
Plant respiration is characterized by the existence of the alternative oxidase pathway (AOP) that competes with cytochrome oxidase pathway (COP) for the electrons of the ubiquinone pool of the mitochondrial electron transport chain, thus reducing ATP synthesis. The oxygen (O2) isotope fractionation technique is the only available to determine the electron partitioning between the two pathways and their in vivo activities in plant tissues. In this chapter, the basis of the O2 isotope fractionation technique and its derived calculations are carefully explained together with a detailed description of the dual-inlet isotope ratio mass spectrometry (DI-IRMS) system and the protocol developed at the University of Balearic Islands. The key advantages of the DI-IRMS over other systems are highlighted as well as the potential problems of this technique. Among these problems, those associated with leakage, diffusion, and inhibitor treatments are noted and solutions to prevent, detect, and repair these problems are detailed.
Collapse
|
6
|
AOX1-Subfamily Gene Members in Olea europaea cv. "Galega Vulgar"-Gene Characterization and Expression of Transcripts during IBA-Induced in Vitro Adventitious Rooting. Int J Mol Sci 2018; 19:ijms19020597. [PMID: 29462998 PMCID: PMC5855819 DOI: 10.3390/ijms19020597] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 02/05/2018] [Accepted: 02/08/2018] [Indexed: 12/21/2022] Open
Abstract
Propagation of some Olea europaea L. cultivars is strongly limited due to recalcitrant behavior in adventitious root formation by semi-hardwood cuttings. One example is the cultivar ”Galega vulgar”. The formation of adventitious roots is considered a morphological response to stress. Alternative oxidase (AOX) is the terminal oxidase of the alternative pathway of the plant mitochondrial electron transport chain. This enzyme is well known to be induced in response to several biotic and abiotic stress situations. This work aimed to characterize the alternative oxidase 1 (AOX1)-subfamily in olive and to analyze the expression of transcripts during the indole-3-butyric acid (IBA)-induced in vitro adventitious rooting (AR) process. OeAOX1a (acc. no. MF410318) and OeAOX1d (acc. no. MF410319) were identified, as well as different transcript variants for both genes which resulted from alternative polyadenylation events. A correlation between transcript accumulation of both OeAOX1a and OeAOX1d transcripts and the three distinct phases (induction, initiation, and expression) of the AR process in olive was observed. Olive AOX1 genes seem to be associated with the induction and development of adventitious roots in IBA-treated explants. A better understanding of the molecular mechanisms underlying the stimulus needed for the induction of adventitious roots may help to develop more targeted and effective rooting induction protocols in order to improve the rooting ability of difficult-to-root cultivars.
Collapse
|
7
|
Shukla P, Singh S, Dubey P, Singh A, Singh AK. Nitric oxide mediated amelioration of arsenic toxicity which alters the alternative oxidase (Aox1) gene expression in Hordeum vulgare L. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2015; 120:59-65. [PMID: 26036416 DOI: 10.1016/j.ecoenv.2015.05.030] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2014] [Revised: 05/16/2015] [Accepted: 05/18/2015] [Indexed: 06/04/2023]
Abstract
The role of nitric oxide (NO) as a key molecule in the signal transduction pathway of a biotic stress response has already been described. Recent studies indicate that it also participate in the signaling of abiotic stresses. In the present study, we showed the altered expression of stress responsive gene alternative oxidase (Aox1) in seedlings of barley (Hordeum vulgare L.) in response to arsenic toxicity. Arsenic toxicity decreased the germination percentage, biomass, chlorophyll and carotenoid content whereas, arsenic toxicity enhanced the MDA content and proline content in a dose dependent manner. Other enzyme activities like catalase and superoxide dismutase increased with the increase in concentrations but it fell down at higher concentration of arsenic. Pretreatment of nitric oxide results in the enhanced expression of alternative oxidase which showed the adaptation of alternative pathway during the arsenic stress and it also enhances the growth ability and adaptability towards the arsenic stress. The results support the conclusion that nitric oxide ameliorates the arsenic toxicity not only at the level of antioxidant defense but also by affecting other mechanism of detoxification.
Collapse
Affiliation(s)
- Pratiksha Shukla
- (a) Genotoxic Lab, Department of Botany, Udai Pratap Autonomous college, Varanasi 221002, India.
| | | | | | - Aradhana Singh
- (a) Genotoxic Lab, Department of Botany, Udai Pratap Autonomous college, Varanasi 221002, India
| | - A K Singh
- (a) Genotoxic Lab, Department of Botany, Udai Pratap Autonomous college, Varanasi 221002, India
| |
Collapse
|
8
|
Mróz TL, Havey MJ, Bartoszewski G. Cucumber Possesses a Single Terminal Alternative Oxidase Gene That is Upregulated by Cold Stress and in the Mosaic (MSC) Mitochondrial Mutants. PLANT MOLECULAR BIOLOGY REPORTER 2015; 33:1893-1906. [PMID: 26752808 PMCID: PMC4695503 DOI: 10.1007/s11105-015-0883-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Alternative oxidase (AOX) is a mitochondrial terminal oxidase which is responsible for an alternative route of electron transport in the respiratory chain. This nuclear-encoded enzyme is involved in a major path of survival under adverse conditions by transfer of electrons from ubiquinol instead of the main cytochrome pathway. AOX protects against unexpected inhibition of the cytochrome c oxidase pathway and plays an important role in stress tolerance. Two AOX subfamilies (AOX1 and AOX2) exist in higher plants and are usually encoded by small gene families. In this study, genome-wide searches and cloning were completed to identify and characterize AOX genes in cucumber (Cucumis sativus L.). Our results revealed that cucumber possesses no AOX1 gene(s) and only a single AOX2 gene located on chromosome 4. Expression studies showed that AOX2 in wild-type cucumber is constitutively expressed at low levels and is upregulated by cold stress. AOX2 transcripts and protein were detected in leaves and flowers of wild-type plants, with higher levels in the three independently derived mosaic (MSC) mitochondrial mutants. Because cucumber possesses a single AOX gene and its expression increases under cold stress and in the MSC mutants, this plant is a unique and intriguing model to study AOX expression and regulation particularly in the context of mitochondria-to-nucleus retrograde signaling.
Collapse
Affiliation(s)
- Tomasz L. Mróz
- />Department of Plant Genetics, Breeding and Biotechnology, Faculty of Horticulture, Biotechnology and Landscape Architecture, Warsaw University of Life Sciences, ul. Nowoursynowska 159, 02-776 Warsaw, Poland
| | - Michael J. Havey
- />Agricultural Research Service, U.S. Department of Agriculture, Vegetable Crops Unit, Department of Horticulture, University of Wisconsin, 1575 Linden Dr., Madison, WI 53706 USA
| | - Grzegorz Bartoszewski
- />Department of Plant Genetics, Breeding and Biotechnology, Faculty of Horticulture, Biotechnology and Landscape Architecture, Warsaw University of Life Sciences, ul. Nowoursynowska 159, 02-776 Warsaw, Poland
| |
Collapse
|
9
|
Naydenov N, Takumi S, Sugie A, Ogihara Y, Atanassov A, Nakamura C. Structural Diversity of the Wheat Nuclear GeneWaox1aEncoding Mitochondrial Alternative Oxidase, A Single Unique Enzyme In The Cyanide-Resistant Alternative Pathway. BIOTECHNOL BIOTEC EQ 2014. [DOI: 10.1080/13102818.2005.10817153] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
|
10
|
Cavalcanti JHF, Oliveira GM, Saraiva KDDC, Torquato JPP, Maia IG, de Melo DF, Costa JH. Identification of duplicated and stress-inducible Aox2b gene co-expressed with Aox1 in species of the Medicago genus reveals a regulation linked to gene rearrangement in leguminous genomes. JOURNAL OF PLANT PHYSIOLOGY 2013; 170:1609-19. [PMID: 23891563 DOI: 10.1016/j.jplph.2013.06.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 06/08/2013] [Accepted: 06/21/2013] [Indexed: 05/24/2023]
Abstract
In flowering plants, alternative oxidase (Aox) is encoded by 3-5 genes distributed in 2 subfamilies (Aox1 and Aox2). In several species only Aox1 is reported as a stress-responsive gene, but in the leguminous Vigna unguiculata Aox2b is also induced by stress. In this work we investigated the Aox genes from two leguminous species of the Medicago genus (Medicago sativa and Medicago truncatula) which present one Aox1, one Aox2a and an Aox2b duplication (named here Aox2b1 and Aox2b2). Expression analyses by semi-quantitative RT-PCR in M. sativa revealed that Aox1, Aox2b1 and Aox2b2 transcripts increased during seed germination. Similar analyses in leaves and roots under different treatments (SA, PEG, H2O2 and cysteine) revealed that these genes are also induced by stress, but with peculiar spatio-temporal differences. Aox1 and Aox2b1 showed basal levels of expression under control conditions and were induced by stress in leaves and roots. Aox2b2 presented a dual behavior, i.e., it was expressed only under stress conditions in leaves, and showed basal expression levels in roots that were induced by stress. Moreover, Aox2a was expressed at higher levels in leaves and during seed germination than in roots and appeared to be not responsive to stress. The Aox expression profiles obtained from a M. truncatula microarray dataset also revealed a stress-induced co-expression of Aox1, Aox2b1 and Aox2b2 in leaves and roots. These results reinforce the stress-inducible co-expression of Aox1/Aox2b in some leguminous plants. Comparative genomic analysis indicates that this regulation is linked to Aox1/Aox2b proximity in the genome as a result of the gene rearrangement that occurred in some leguminous plants during evolution. The differential expression of Aox2b1/2b2 suggests that a second gene has been originated by recent gene duplication with neofunctionalization.
Collapse
MESH Headings
- Chromosomes, Plant/genetics
- Gene Expression Profiling
- Gene Expression Regulation, Plant
- Gene Rearrangement/genetics
- Genes, Duplicate/genetics
- Genes, Plant/genetics
- Genome, Plant/genetics
- Germination/genetics
- Medicago/drug effects
- Medicago/enzymology
- Medicago/genetics
- Mitochondrial Proteins/genetics
- Mitochondrial Proteins/metabolism
- Molecular Sequence Data
- Oxidoreductases/genetics
- Oxidoreductases/metabolism
- Phylogeny
- Plant Growth Regulators/pharmacology
- Plant Leaves/enzymology
- Plant Leaves/genetics
- Plant Proteins/genetics
- Plant Proteins/metabolism
- Plant Roots/enzymology
- Plant Roots/genetics
- Promoter Regions, Genetic/genetics
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Stress, Physiological/drug effects
- Stress, Physiological/genetics
Collapse
|
11
|
Neimanis K, Staples JF, Hüner NP, McDonald AE. Identification, expression, and taxonomic distribution of alternative oxidases in non-angiosperm plants. Gene 2013; 526:275-86. [DOI: 10.1016/j.gene.2013.04.072] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 04/23/2013] [Accepted: 04/24/2013] [Indexed: 10/26/2022]
|
12
|
Zhang BY, He LW, Jia ZJ, Wang GC, Peng G. CHARACTERIZATION OF THE ALTERNATIVE OXIDASE GENE IN PORPHYRA YEZOENSIS (RHODOPHYTA) AND CYANIDE-RESISTANT RESPIRATION ANALYSIS(1). JOURNAL OF PHYCOLOGY 2012; 48:657-663. [PMID: 27011081 DOI: 10.1111/j.1529-8817.2012.01129.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The full-length cDNA of the alternative oxidase (AOX) gene from Porphyra yezoensis Ueda (PyAOX) [currently assigned as Pyropia yezoensis (Ueda) M. S. Hwang et H. G. Choi (http://www.algaebase.org)] an ancient member of the Rhodphyta, was cloned by electronic cloning, rapid amplification of cDNA ends (RACE), and reverse transcription PCR. The nucleotide sequence of PyAOX consists of 1,650 bp, including a 5' untranslated region (UTR) of 170 bp, a 3' UTR of 148 bp, and an open reading frame (ORF) of 1,332 bp that can be translated into a 443-amino-acid residue with a molecular mass of 47.33 kDa and a putative isoelectric point (pI) of 9.71. The putative amino acids had 50%-61% identity with AOX genes in Eukaryota and higher plants and had AOX-like characteristics. The expression of PyAOX mRNA in different stages of the life cycle, conchospores, filamentous thalli (conchocelis stage), and leafy thalli, was detected by real-time quantitative PCR (qPCR). The highest level of expression, which was observed in filamentous thalli, was three times higher than that observed in leafy thalli. The next highest level, which was observed in the conchospores, was twice as high as that observed in leafy thalli. We showed that an alternative respiration pathway existed in P. yezoensis with a noninvasive microsensing system. The contribution of the alternative pathway to total respiration in filamentous thalli was greater than that in leafy thalli. This result was consistent with the level of AOX gene expression observed in different stages of the life cycle.
Collapse
Affiliation(s)
- Bao Y Zhang
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, ChinaCollege of Marine Science and Engineering, Tianjin University of Science and Technology, Tianjin, 300457, ChinaKey Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
| | - Lin W He
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, ChinaCollege of Marine Science and Engineering, Tianjin University of Science and Technology, Tianjin, 300457, ChinaKey Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
| | - Zhao J Jia
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, ChinaCollege of Marine Science and Engineering, Tianjin University of Science and Technology, Tianjin, 300457, ChinaKey Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
| | - Guang C Wang
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, ChinaCollege of Marine Science and Engineering, Tianjin University of Science and Technology, Tianjin, 300457, ChinaKey Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
| | - Guang Peng
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, ChinaCollege of Marine Science and Engineering, Tianjin University of Science and Technology, Tianjin, 300457, ChinaKey Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
| |
Collapse
|
13
|
Ma H, Song C, Borth W, Sether D, Melzer M, Hu J. Modified expression of alternative oxidase in transgenic tomato and petunia affects the level of tomato spotted wilt virus resistance. BMC Biotechnol 2011; 11:96. [PMID: 22014312 PMCID: PMC3226446 DOI: 10.1186/1472-6750-11-96] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 10/20/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Tomato spotted wilt virus (TSWV) has a very wide host range, and is transmitted in a persistent manner by several species of thrips. These characteristics make this virus difficult to control. We show here that the over-expression of the mitochondrial alternative oxidase (AOX) in tomato and petunia is related to TSWV resistance. RESULTS The open reading frame and full-length sequence of the tomato AOX gene LeAox1au were cloned and introduced into tomato 'Healani' and petunia 'Sheer Madness' using Agrobacterium-mediated transformation. Highly expressed AOX transgenic tomato and petunia plants were selfed and transgenic R1 seedlings from 10 tomato lines and 12 petunia lines were used for bioassay. For each assayed line, 22 to 32 tomato R1 progeny in three replications and 39 to 128 petunia progeny in 13 replications were challenged with TSWV. Enzyme-Linked Immunosorbent Assays showed that the TSWV levels in transgenic tomato line FKT4-1 was significantly lower than that of wild-type controls after challenge with TSWV. In addition, transgenic petunia line FKP10 showed significantly less lesion number and smaller lesion size than non-transgenic controls after inoculation by TSWV. CONCLUSION In all assayed transgenic tomato lines, a higher percentage of transgenic progeny had lower TSWV levels than non-transgenic plants after challenge with TSWV, and the significantly increased resistant levels of tomato and petunia lines identified in this study indicate that altered expression levels of AOX in tomato and petunia can affect the levels of TSWV resistance.
Collapse
Affiliation(s)
- Hao Ma
- Department of Plant and Environmental Protection Sciences, University of Hawaii, Honolulu, HI 96822, USA
| | | | | | | | | | | |
Collapse
|
14
|
Costa JH, Mota EF, Cambursano MV, Lauxmann MA, de Oliveira LMN, Silva Lima MDG, Orellano EG, Fernandes de Melo D. Stress-induced co-expression of two alternative oxidase (VuAox1 and 2b) genes in Vigna unguiculata. JOURNAL OF PLANT PHYSIOLOGY 2010; 167:561-70. [PMID: 20005596 DOI: 10.1016/j.jplph.2009.11.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Revised: 11/01/2009] [Accepted: 11/02/2009] [Indexed: 05/21/2023]
Abstract
Cowpea (Vigna unguiculata) alternative oxidase is encoded by a small multigene family (Aox1, 2a and 2b) that is orthologous to the soybean Aox family. Like most of the identified Aox genes in plants, VuAox1 and VuAox2 consist of 4 exons interrupted by 3 introns. Alignment of the orthologous Aox genes revealed high identity of exons and intron variability, which is more prevalent in Aox1. In order to determine Aox gene expression in V. unguiculata, a steady-state analysis of transcripts involved in seed development (flowers, pods and dry seeds) and germination (soaked seeds) was performed and systemic co-expression of VuAox1 and VuAox2b was observed during germination. The analysis of Aox transcripts in leaves from seedlings under different stress conditions (cold, PEG, salicylate and H2O2 revealed stress-induced co-expression of both VuAox genes. Transcripts of VuAox2a and 2b were detected in all control seedlings, which was not the case for VuAox1 mRNA. Estimation of the primary transcript lengths of V. unguiculata and soybean Aox genes showed an intron length reduction for VuAox1 and 2b, suggesting that the two genes have converged in transcribed sequence length. Indeed, a bioinformatics analysis of VuAox1 and 2b promoters revealed a conserved region related to a cis-element that is responsive to oxidative stress. Taken together, the data provide evidence for co-expression of Aox1 and Aox2b in response to stress and also during the early phase of seed germination. The dual nature of VuAox2b expression (constitutive and induced) suggests that the constitutive Aox2b gene of V. unguiculata has acquired inducible regulatory elements.
Collapse
Affiliation(s)
- José Hélio Costa
- Department of Biochemistry and Molecular Biology, Federal University of Ceara, 60455-760 Fortaleza, Ceará, Brazil
| | | | | | | | | | | | | | | |
Collapse
|
15
|
Chai TT, Simmonds D, Day DA, Colmer TD, Finnegan PM. Photosynthetic performance and fertility are repressed in GmAOX2b antisense soybean. PLANT PHYSIOLOGY 2010; 152:1638-49. [PMID: 20097793 PMCID: PMC2832272 DOI: 10.1104/pp.109.149294] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Accepted: 01/19/2010] [Indexed: 05/07/2023]
Abstract
The alternative oxidase (AOX) is a cyanide-resistant oxidase that provides an alternative outlet for electrons from the respiratory electron transport chain embedded in the inner membrane of plant mitochondria. Examination of soybean (Glycine max) plants carrying a GmAOX2b antisense gene showed AOX to have a central role in reproductive development and fecundity. In three independently transformed antisense lines, seed set was reduced by 16% to 43%, whereas ovule abortion increased by 1.2- to 1.7-fold when compared with nontransgenic transformation control plants. Reduced fecundity was associated with reductions in whole leaf cyanide-resistant, salicylhydroxamic acid-sensitive respiration and net photosynthesis, but there was no change in total respiration in the dark. The frequency of potential fertilization events was reduced by at least one-third in the antisense plants as a likely consequence of prefertilization defects. Pistils of the antisense plants contained a higher proportion of immature-sized, nonfertile embryo sacs compared with nontransgenic control plants. Increased rates of pollen abortion in vivo and reduced rates of pollen germination in vitro suggested that the antisense gene compromised pollen development and function. Reciprocal crosses between antisense and nontransgenic plants revealed that pollen produced by antisense plants was less active in fertilization. Taken together, the results presented here indicate that AOX expression has an important role in determining normal gametophyte development and function.
Collapse
Affiliation(s)
| | | | | | | | - Patrick M. Finnegan
- School of Plant Biology and Institute of Agriculture, Faculty of Natural and Agricultural Sciences, University of Western Australia, Crawley, Western Australia 6009, Australia (T.-T.C., T.D.C., P.M.F.); Agriculture and Agri-Food Canada, Ottawa, Ontario, Canada K1A 0C6 (D.S.); and Australian Research Council Centre of Excellence in Plant Energy Biology, School of Biological Sciences, Flinders University, Adelaide, South Australia 5001, Australia (D.A.D.)
| |
Collapse
|
16
|
Costa JH, de Melo DF, Gouveia Z, Cardoso HG, Peixe A, Arnholdt-Schmitt B. The alternative oxidase family of Vitis vinifera reveals an attractive model to study the importance of genomic design. PHYSIOLOGIA PLANTARUM 2009; 137:553-65. [PMID: 19682279 DOI: 10.1111/j.1399-3054.2009.01267.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
'Genomic design' refers to the structural organization of gene sequences. Recently, the role of intron sequences for gene regulation is being better understood. Further, introns possess high rates of polymorphism that are considered as the major source for speciation. In molecular breeding, the length of gene-specific introns is recognized as a tool to discriminate genotypes with diverse traits of agronomic interest. 'Economy selection' and 'time-economy selection' have been proposed as models for explaining why highly expressed genes typically contain small introns. However, in contrast to these theories, plant-specific selection reveals that highly expressed genes contain introns that are large. In the presented research, 'wet'Aox gene identification from grapevine is advanced by a bioinformatics approach to study the species-specific organization of Aox gene structures in relation to available expressed sequence tag (EST) data. Two Aox1 and one Aox2 gene sequences have been identified in Vitis vinifera using grapevine cultivars from Portugal and Germany. Searching the complete genome sequence data of two grapevine cultivars confirmed that V. vinifera alternative oxidase (Aox) is encoded by a small multigene family composed of Aox1a, Aox1b and Aox2. An analysis of EST distribution revealed high expression of the VvAox2 gene. A relationship between the atypical long primary transcript of VvAox2 (in comparison to other plant Aox genes) and its expression level is suggested. V. vinifera Aox genes contain four exons interrupted by three introns except for Aox1a which contains an additional intron in the 3'-UTR. The lengths of primary Aox transcripts were estimated for each gene in two V. vinifera varieties: PN40024 and Pinot Noir. In both varieties, Aox1a and Aox1b contained small introns that corresponded to primary transcript lengths ranging from 1501 to 1810 bp. The Aox2 of PN40024 (12 329 bp) was longer than that from Pinot Noir (7279 bp) because of selection against a transposable-element insertion that is 5028 bp in size. An EST database basic local alignment search tool (BLAST) search of GenBank revealed the following ESTs percentages for each gene: Aox1a (26.2%), Aox1b (11.9%) and Aox2 (61.9%). Aox1a was expressed in fruits and roots, Aox1b expression was confined to flowers and Aox2 was ubiquitously expressed. These data for V. vinifera show that atypically long Aox intron lengths are related to high levels of gene expression. Furthermore, it is shown for the first time that two grapevine cultivars can be distinguished by Aox intron length polymorphism.
Collapse
Affiliation(s)
- José Hélio Costa
- Department of Biochemistry and Molecular Biology, Federal University of Ceará, PO Box 6029, 60455-900, Fortaleza, Ceará, Brazil
| | | | | | | | | | | |
Collapse
|
17
|
Van Aken O, Giraud E, Clifton R, Whelan J. Alternative oxidase: a target and regulator of stress responses. PHYSIOLOGIA PLANTARUM 2009; 137:354-61. [PMID: 19470093 DOI: 10.1111/j.1399-3054.2009.01240.x] [Citation(s) in RCA: 143] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The alternative oxidase (AOX) is found in all plants examined to date, fungi and lower invertebrates. We propose that AOX is not only part of the stress response in plants, but it also plays a central role in defining the stress response. Three lines of evidence support this proposal: (1) The absence of AOX leads to an alteration of stress defences in normal and stress conditions, (2) the expression of AOX is triggered by a variety of signals indicating that it is a common response and (3) AOX acts as a buffer that determines the threshold for the induction of programmed cell death. Therefore, AOX is not only one of many components involved in the defence response, its activity or lack of activity leads to a radical alteration of the defence equilibrium at a cellular level and thus it plays a central role in programming the stress response. This programming role of AOX can be achieved directly by its ability to suppress the induction of reactive oxygen species (ROS) and indirectly by causing changes in the energy status of cells owing to the non-phosphorylating nature of the alternative respiratory pathway. The latter is likely achieved in combination with a variety of alternative NAD(P)H dehydrogenases, that are co-regulated with AOX. Additionally, we explore the possible function of AOX as a component of the stress response beyond the plant frontier.
Collapse
Affiliation(s)
- Olivier Van Aken
- ARC Centre of Excellence Plant Energy Biology, University of Western Australia, 35 Stirling Highway, 6009 Crawley, Western Australia, Australia.
| | | | | | | |
Collapse
|
18
|
Frederico AM, Zavattieri MA, Campos MD, Cardoso HG, McDonald AE, Arnholdt-Schmitt B. The gymnosperm Pinus pinea contains both AOX gene subfamilies, AOX1 and AOX2. PHYSIOLOGIA PLANTARUM 2009; 137:566-77. [PMID: 19863755 DOI: 10.1111/j.1399-3054.2009.01279.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The gymnosperm Pinus pinea L. (stone pine) is a typical Mediterranean pine used for nuts and timber production, and as an ornamental around the world. Pine genomes are large in comparison to other species. The hypothesis that retrotransposons, such as gymny, made a large contribution to this alteration in genome size was recently confirmed. However, P. pinea is unique in other various aspects. P. pinea demonstrates a different pattern of gymny organization than other Pinus subgenera. Additionally, P. pinea has a highly recalcitrant behaviour in relation to standard conifer protocols for the induction of somatic embryogenesis or rooting. Because such types of cell reprogramming can be explained as a reaction of plant cells to external stress, it is of special interest to study sequence peculiarities in stress-inducible genes, such as the alternative oxidase (AOX). This is the first report containing molecular evidence for the existence of AOX in gymnosperms at the genetic level. P. pinea AOXs were isolated by a polymerase chain reaction (PCR) approach and three genes were identified. Two of the genes belong to the AOX1 subfamily and one belongs to the AOX2 subfamily. The existence of both AOX subfamilies in gymnosperms is reported here for the first time. This discovery supports the hypothesis that AOX1 and AOX2 subfamilies arose prior to the separation of gymnosperms and angiosperms, and indicates that the AOX2 is absent in monocots because of subsequent gene loss events. Polymorphic P. pinea AOX1 sequences from a selected genetic clone are presented indicating non-allelic, non-synonymous and synonymous translation products.
Collapse
|
19
|
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.
Collapse
Affiliation(s)
- Allison E McDonald
- Department of Biology, The University of Western Ontario, 1151 Richmond St. N., London, Ontario N6A5B7, Canada.
| |
Collapse
|
20
|
Matos AR, Mendes AT, Scotti-Campos P, Arrabaça JD. Study of the effects of salicylic acid on soybean mitochondrial lipids and respiratory properties using the alternative oxidase as a stress-reporter protein. PHYSIOLOGIA PLANTARUM 2009; 137:485-97. [PMID: 19508334 DOI: 10.1111/j.1399-3054.2009.01250.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Biotic and abiotic stresses can lead to modifications in the lipid composition of cell membranes. Although mitochondria appear to be implicated in stress responses, little is known about the membrane lipid changes that occur in these organelles in plants. Besides cytochrome c oxidase, plant mitochondria have an alternative oxidase (AOX) that accepts electrons directly from ubiquinol, dissipating energy as heat. AOX upregulation occurs under a variety of stresses and its induction by salicylic acid (SA) has been observed in different plant species. AOX was also suggested to be used as a functional marker for cell reprogramming under stress. In the present study, we have used etiolated soybean (Glycine max (L.) Merr. cv Cresir) seedlings to study the effects of SA treatment on the lipid composition and the respiratory properties of hypocotyl mitochondria. AOX expression was studied in detail, as a reporter protein, to evaluate whether modifications in mitochondrial energy metabolism were occurring. In mitochondria extracted from SA-treated seedlings, AOX capacity and protein contents increased. Both AOX1 and AOX2b transcripts accumulated in response to SA, but with different kinetics. A reduction in external NADH oxidation capacity was observed, whereas succinate respiration remained unchanged. The phospholipid composition of mitochondria remained similar in control and SA-treated plants, but a reduction in the relative amount of linolenic acid was observed in phosphatidylcholine, phosphatidylethanolamine and cardiolipin. The possible causes of the fatty acid modifications observed, and the implications for mitochondrial metabolism are discussed.
Collapse
Affiliation(s)
- Ana Rita Matos
- Centro de Engenharia Biológica, Departamento de Biologia Vegetal, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal.
| | | | | | | |
Collapse
|
21
|
Wang J, Wang X, Liu C, Zhang J, Zhu C, Guo X. The NgAOX1a gene cloned from Nicotiana glutinosa is implicated in the response to abiotic and biotic stresses. Biosci Rep 2008; 28:259-66. [PMID: 18588517 DOI: 10.1042/bsr20080025] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
A novel gene, named NgAOX1a, was isolated from Nicotiana glutinosa by RT-PCR (reverse transcription-PCR). The full-length cDNA of NgAOX1a was 1448 bp, including a 1062-bp ORF (open reading frame), a 124 bp 5' UTR (untranslated region) and a 262 bp 3' UTR. The ORF encodes a 353-amino-acid protein which contains two conserved cysteine residues, four iron-binding motifs, five alpha-helix regions and six conserved histidine residues. The phylogenetic tree showed that NgAOX1a belongs to the AOX1 (alternative oxidase 1)-type group. Alignment analysis showed that NgAOX1a shares a high similarity with other known AOXs. Four exons and three introns were detected in the genomic DNA sequence, and Southern-blotting analysis suggested that NgAOX1a is a single-copy gene. A series of putative cis-acting elements were examined in the 5'-flanking region of NgAOX1a. Northern-blotting analysis showed that the transcript levels of NgAOX1a can be markedly accumulated when tobacco seedlings are treated with various abiotic stimuli, such as exogenous signalling molecules for plant defence response, salicylic acid and H(2)O(2), and the exogenous TCA (tricarboxylic acid) cycle metabolite citrate. However, it could be suppressed by abiotic stress, such as CoCl(2), an inhibitor of ethylene, which indicates that the expression of NgAOX1a may be regulated by ethylene. In addition, NgAOX1a can also be strongly induced by three viral pathogens, tobacco mosaic virus, potato virus X and potato virus Y. These results indicate that NgAOX1a may be involved in multi-signal transduction pathways and may play an important role in defence response.
Collapse
Affiliation(s)
- Jian Wang
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, 271018, People's Republic of China
| | | | | | | | | | | |
Collapse
|
22
|
McDonald AE. Alternative oxidase: an inter-kingdom perspective on the function and regulation of this broadly distributed 'cyanide-resistant' terminal oxidase. FUNCTIONAL PLANT BIOLOGY : FPB 2008; 35:535-552. [PMID: 32688810 DOI: 10.1071/fp08025] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2008] [Accepted: 07/11/2008] [Indexed: 06/11/2023]
Abstract
Alternative oxidase (AOX) is a terminal quinol oxidase located in the respiratory electron transport chain that catalyses the oxidation of quinol and the reduction of oxygen to water. However, unlike the cytochrome c oxidase respiratory pathway, the AOX pathway moves fewer protons across the inner mitochondrial membrane to generate a proton motive force that can be used to synthesise ATP. The energy passed to AOX is dissipated as heat. This appears to be very wasteful from an energetic perspective and it is likely that AOX fulfils some physiological function(s) that makes up for its apparent energetic shortcomings. An examination of the known taxonomic distribution of AOX and the specific organisms in which AOX has been studied has been used to explore themes pertaining to AOX function and regulation. A comparative approach was used to examine AOX function as it relates to the biochemical function of the enzyme as a quinol oxidase and associated topics, such as enzyme structure, catalysis and transcriptional expression and post-translational regulation. Hypotheses that have been put forward about the physiological function(s) of AOX were explored in light of some recent discoveries made with regard to species that contain AOX. Fruitful areas of research for the AOX community in the future have been highlighted.
Collapse
Affiliation(s)
- Allison E McDonald
- Department of Biology, The University of Western Ontario, Biological and Geological Sciences Building, London, Ontario N6A 5B7, Canada. Email
| |
Collapse
|
23
|
Liu YJ, Norberg FEB, Szilágyi A, De Paepe R, Akerlund HE, Rasmusson AG. The mitochondrial external NADPH dehydrogenase modulates the leaf NADPH/NADP+ ratio in transgenic Nicotiana sylvestris. PLANT & CELL PHYSIOLOGY 2008; 49:251-63. [PMID: 18182402 DOI: 10.1093/pcp/pcn001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Plant mitochondria contain alternative external NAD(P)H dehydrogenases, which oxidize cytosolic NADH or NADPH and reduce ubiquinone without inherent linkage to proton pumping and ATP production. In potato, St-NDB1 is an external Ca2+-dependent NADPH dehydrogenase. The physiological function of this enzyme was investigated in homozygous Nicotiana sylvestris lines overexpressing St-ndb1 and co-suppressing St-ndb1 and an N. sylvestris ndb1. In leaf mitochondria isolated from the overexpressor lines, higher activity of alternative oxidase (AOX) was detected. However, the AOX induction was substantially weaker than in the complex I-deficient CMSII mutant, previously shown to contain elevated amounts of NAD(P)H dehydrogenases and AOX. An aox1b and an aox2 gene were up-regulated in CMSII, but only aox1b showed a response, albeit smaller, in the transgenic lines, indicating differences in AOX activation between the genotypes. As in CMSII, the increase of AOX in the overexpressing lines was not due to a general oxidative stress. The lines overexpressing St-ndb1 had consistently lowered leaf NADPH/NADP+ ratios in the light and variably decreased levels in darkness, but unchanged NADH/NAD+ ratios. CMSII instead had similar NADPH/NADP+ and lower NADH/NAD+ ratios than the wild type. These results demonstrate that St-NDB1 is able to modulate the cellular balance of NADPH and NADP+ at least in the day and that reduction of NADP(H) and NAD(H) is independently controlled. Similar growth rates, chloroplast malate dehydrogenase activation and xanthophyll ratios indicate that the change in reduction does not communicate to the chloroplast, and that the cell tolerates significant changes in NADP(H) reduction without deleterious effects.
Collapse
Affiliation(s)
- Yun-Jun Liu
- Lund University, Department of Cell and Organism Biology, Sölvegatan 35B, SE-22362 Lund, Sweden
| | | | | | | | | | | |
Collapse
|
24
|
Costa JH, Jolivet Y, Hasenfratz-Sauder MP, Orellano EG, da Guia Silva Lima M, Dizengremel P, Fernandes de Melo D. Alternative oxidase regulation in roots of Vigna unguiculata cultivars differing in drought/salt tolerance. JOURNAL OF PLANT PHYSIOLOGY 2007; 164:718-27. [PMID: 16716451 DOI: 10.1016/j.jplph.2006.04.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2006] [Accepted: 04/05/2006] [Indexed: 05/09/2023]
Abstract
The alternative oxidase (Aox) was studied at different levels (transcript, protein and capacity) in response to an osmotic shock applied to roots of cowpea (Vigna unguiculata). Two cultivars of V. unguiculata were used, Vita 3 and Vita 5, tolerant and sensitive to drought/saline stress respectively. The seedlings (17-day-old) were grown in hydroponic conditions and submitted to NaCl (100 and 200 mM) or 200.67 g L(-1) PEG 6000 (iso-osmotic condition to 100 mM NaCl). The VuAox1 and VuAox2a mRNA were not detected in either cultivar under all tested conditions while the VuAox2b gene was differently expressed. In the tolerant cultivar (Vita 3), the expression of VuAox2b gene was stimulated by an osmotic stress induced by PEG which was associated with a higher amount and capacity of the Aox protein. In the same cultivar, this gene was under-expressed in salt stress conditions with poor effect on the protein level. In the sensitive cultivar (Vita 5), the transcript level of the VuAox2b was unchanged in response to PEG treatment, even though the protein and the capacity tended to increase. Upon salt stress, the VuAox2b gene was over-expressed. At 100mM NaCl, this VuAox2b gene over-expression led to a higher amount and capacity of Aox. This effect was reduced at 200 mM NaCl. Overall, these results suggest complex mechanisms (transcriptional, translational and post-translational) for Aox regulation in response to osmotic stress.
Collapse
Affiliation(s)
- José Hélio Costa
- Department of Biochemistry and Molecular Biology, Federal University of Ceará, P.O. Box 6029, 60455-760 Fortaleza Ceará, Brazil
| | | | | | | | | | | | | |
Collapse
|
25
|
Li F, Zhang Y, Wang M, Zhang Y, Wu X, Guo X. Molecular cloning and expression characteristics of alternative oxidase gene of cotton (Gossypium hirsutum). Mol Biol Rep 2007; 35:97-105. [PMID: 17351819 DOI: 10.1007/s11033-007-9058-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2006] [Accepted: 01/17/2007] [Indexed: 10/23/2022]
Abstract
A novel alternative oxidase (AOX) gene derived from cotton (Gossypium hirsutum), designated as GhAOX1, was cloned with RACE-PCR. The full-length cDNA of GhAOX1was 1,298 bp in size, containing a 996 bp open reading frame (ORF) which corresponds to a precursor protein of 332 amino acid residues with a calculated molecular mass of 37.5 kDa. The predicted amino acid sequence exhibited 68.4%, 68.1%, 59.4%, and 69.8% homology to the alternative oxidases of Arabidopsis thaliana, Nicotiana tabacum, Solanum tuberosum and Glycine max, respectively. Interestingly, striking similarity in several coding regions, such as metal binding and hydrophobic alpha-helix regions was seen between GhAOX1 and other AOX1 proteins. Analysis of the exon/intron structure of the GhAOX1 gene showed that GhAOX1 consisted of four exons and three introns. Southern analysis indicated that the GhAOX1 was a single copy gene belonging to a multi-gene family. Expression analysis by Northern blot revealed that the GhAOX1 exhibited preferential expression in tissues, with the higher expression being found in cotyledons and petals. GhAOX1 was also found to be induced by a variety of stresses stimulation including cold, citrate, SA, KCN and antimycin A in cotton.
Collapse
Affiliation(s)
- Fang Li
- Shandong Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, 271018, Taian, Shandong, China
| | | | | | | | | | | |
Collapse
|
26
|
Chae MS, Lin CC, Kessler KE, Nargang CE, Tanton LL, Hahn LB, Nargang FE. Identification of an alternative oxidase induction motif in the promoter region of the aod-1 gene in Neurospora crassa. Genetics 2007; 175:1597-606. [PMID: 17237510 PMCID: PMC1855127 DOI: 10.1534/genetics.106.068635] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The nuclear aod-1 gene of Neurospora crassa encodes the alternative oxidase and is induced when the standard cytochrome-mediated respiratory chain of mitochondria is inhibited. To study elements of the pathway responsible for alternative oxidase induction, we generated a series of mutations in the region upstream from the aod-1 structural gene and transformed the constructs into an aod-1 mutant strain. Transformed conidia were plated on media containing antimycin A, which inhibits the cytochrome-mediated electron transport chain so that only cells expressing alternative oxidase will grow. Using this functional in vivo assay, we identified an alternative oxidase induction motif (AIM) that is required for efficient expression of aod-1. The AIM sequence consists of two CGG repeats separated by 7 bp and is similar to sequences known to be bound by members of the Zn(II)2Cys6 binuclear cluster family of transcription factors. The AIM motif appears to be conserved in other species found in the order Sordariales.
Collapse
Affiliation(s)
- Michael S Chae
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | | | | | | | | | | | | |
Collapse
|
27
|
Polidoros AN, Mylona PV, Pasentsis K, Scandalios JG, Tsaftaris AS. The maize alternative oxidase 1a (Aox1a) gene is regulated by signals related to oxidative stress. Redox Rep 2006; 10:71-8. [PMID: 15949126 DOI: 10.1179/135100005x21688] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
We isolated and characterized the expression of Aox1a, a member of the maize alternative oxidase (Aox) small multigene family. Aox1a consists of four exons interrupted by three introns and its promoter harbors diverse stress-specific putative regulatory motifs pointing to complex regulation and response to multiple signals. Responses of Aox1a to such signals were examined and compared with those of maize glutathione S-transferase I (GstI), a typical oxidative stress inducible gene. Potassium cyanide (KCN) and hydrogen peroxide (H2O2) induced a rapid increase of the Aox1a and GstI transcripts, which was persisted in prolonged treatment at high H2O2 concentration only for Aox1a. High concentration of salicylic acid (SA) and salicyl hydroxamic acid (SHAM) induced Aox1a mRNA only after prolonged exposure, while GstI displayed an early strong induction, which declined thereafter. Nitric oxide (NO) induced a high increase of Aox1a after prolonged exposure at high concentration, while GstI displayed a weak response. Our results show that multiple signaling pathways, involved in stress responses, also participate and differentially regulate Aox1a and GstI in maize. A ROS-depended signaling event may be involved, suggesting an essential role of Aox1a under oxidative stress in maize.
Collapse
Affiliation(s)
- Alexios N Polidoros
- Institute of Agrobiotechnology, Center for Research and Technology Hellas, Thermi, Greece.
| | | | | | | | | |
Collapse
|
28
|
Descheneau AT, Cleary IA, Nargang FE. Genetic evidence for a regulatory pathway controlling alternative oxidase production in Neurospora crassa. Genetics 2005; 169:123-35. [PMID: 15466423 PMCID: PMC1448880 DOI: 10.1534/genetics.104.034017] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2004] [Accepted: 09/22/2004] [Indexed: 11/18/2022] Open
Abstract
When the cytochrome-mediated mitochondrial electron transport chain of Neurospora crassa is disrupted, an alternative oxidase encoded by the nuclear aod-1 gene is induced. The alternative oxidase donates electrons directly to oxygen from the ubiquininol pool and is insensitive to chemicals such as antimycin A and KCN that affect the standard electron transport chain. To facilitate isolation of mutants affecting regulation of aod-1, a reporter system containing the region upstream of the aod-1 coding sequence fused to the coding sequence of the N. crassa tyrosinase gene (T) was transformed into a strain carrying a null allele of the endogenous T gene. In the resulting reporter strain, growth in the presence of chloramphenicol, an inhibitor of mitochondrial translation whose action decreases the level of mitochondrial translation products resulting in impaired cytochrome-mediated respiration, caused induction of both alternative oxidase and tyrosinase. Conidia from the reporter strain were mutagenized, plated on medium containing chloramphenicol, and colonies that did not express tyrosinase were identified as potential regulatory mutants. After further characterization, 15 strains were found that were unable to induce both the reporter and the alternative oxidase. Complementation analysis revealed that four novel loci involved in aod-1 regulation had been isolated. The discovery that several genes are required for regulation of aod-1 suggests the existence of a complex pathway for signaling from the mitochondria to the nucleus and/or for expression of the gene.
Collapse
Affiliation(s)
- Andrea T Descheneau
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | | | | |
Collapse
|
29
|
Gray GR, Maxwell DP, Villarimo AR, McIntosh L. Mitochondria/nuclear signaling of alternative oxidase gene expression occurs through distinct pathways involving organic acids and reactive oxygen species. PLANT CELL REPORTS 2004; 23:497-503. [PMID: 15322810 DOI: 10.1007/s00299-004-0848-1] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2004] [Revised: 07/06/2004] [Accepted: 07/09/2004] [Indexed: 05/04/2023]
Abstract
Cultured cells of tobacco (Nicotiana tabacum L. cv Petit Havana) were used to investigate signals regulating the expression of the "model" nuclear gene encoding the alternative oxidase (AOX) (AOX1), the terminal oxidase of the mitochondrial alternative respiratory pathway. Several conditions shown to induce AOX1 mRNA accumulation also result in an increase in cellular citrate concentrations, suggesting that citrate and/or other tricarboxylic acid (TCA) cycle intermediates may be important signal metabolites. In addition, mitochondrial reactive oxygen species (ROS) production has recently been shown to be a factor mediating mitochondria-to-nucleus signaling for the expression of AOX1. We found that the exogenously supplied TCA cycle organic acids citrate, malate and 2-oxoglutarate caused rapid and dramatic increases in the steady-state level of AOX1 mRNA at low, near physiological concentrations (0.1 mM). Furthermore, an increase in AOX1 induced by the addition of organic acids occurs independently of mitochondrial ROS formation. Our results demonstrate that two separate pathways for mitochondria-to-nucleus signaling of AOX1 may exist, one involving ROS and the other organic acids.
Collapse
Affiliation(s)
- G R Gray
- Department of Plant Sciences, University of Saskatchewan, Saskatoon, SK, Canada, S7N 5A8.
| | | | | | | |
Collapse
|
30
|
Finnegan PM, Soole KL, Umbach AL. Alternative Mitochondrial Electron Transport Proteins in Higher Plants. PLANT MITOCHONDRIA: FROM GENOME TO FUNCTION 2004. [DOI: 10.1007/978-1-4020-2400-9_9] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
|
31
|
Thirkettle-Watts D, McCabe TC, Clifton R, Moore C, Finnegan PM, Day DA, Whelan J. Analysis of the alternative oxidase promoters from soybean. PLANT PHYSIOLOGY 2003; 133:1158-69. [PMID: 14551329 PMCID: PMC281611 DOI: 10.1104/pp.103.028183] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2003] [Revised: 08/01/2003] [Accepted: 08/01/2003] [Indexed: 05/18/2023]
Abstract
Alternative oxidase (Aox) is a nuclear-encoded mitochondrial protein. In soybean (Glycine max), the three members of the gene family have been shown to be differentially expressed during normal plant development and in response to stresses. To examine the function of the Aox promoters, genomic fragments were obtained for all three soybean genes: Aox1, Aox2a, and Aox2b. The regions of these fragments immediately upstream of the coding regions were used to drive beta-glucuronidase (GUS) expression during transient transformation of soybean suspension culture cells and stable transformation of Arabidopsis. The expression patterns of the GUS reporter genes in soybean cells were in agreement with the presence or absence of the various endogenous Aox proteins, determined by immunoblotting. Deletion of different portions of the upstream regions identified sequences responsible for both positive and negative regulation of Aox gene expression in soybean cells. Reporter gene analysis in Arabidopsis plants showed differential tissue expression patterns driven by the three upstream regions, similar to those reported for the endogenous proteins in soybean. The expression profiles of all five members of the Arabidopsis Aox gene family were examined also, to compare with GUS expression driven by the soybean upstream fragments. Even though the promoter activity of the upstream fragments from soybean Aox2a and Aox2b displayed the same tissue specificity in Arabidopsis as they do in soybean, the most prominently expressed endogenous genes in all tissues of Arabidopsis were of the Aox1 type. Thus although regulation of Aox expression generally appears to involve the same signals in different species, different orthologs of Aox may respond variously to these signals. A comparison of upstream sequences between soybean Aox genes and similarly expressed Arabidopsis Aox genes identified common motifs.
Collapse
Affiliation(s)
- David Thirkettle-Watts
- Plant Molecular Biology Group, Biochemistry and Molecular Biology, School of Biomedical and Chemical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia, Australia
| | | | | | | | | | | | | |
Collapse
|
32
|
Holtzapffel RC, Castelli J, Finnegan PM, Millar AH, Whelan J, Day DA. A tomato alternative oxidase protein with altered regulatory properties. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2003; 1606:153-62. [PMID: 14507436 DOI: 10.1016/s0005-2728(03)00112-9] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
We have investigated the expression and regulatory properties of the two alternative oxidase (Aox) proteins that are expressed in tomato (Lycopersicon esculentum L. Mill cv. Sweetie) after storage of green fruit at 4 degrees C. Four Aox genes were identified in the tomato genome, of which two (LeAox1a and LeAox1b) were demonstrated to be expressed in cold-treated fruit. The activity and regulatory properties of LeAox1a and LeAox1b were assayed after expression of each protein in yeast cells (Saccharomyces cerevisiae), proving that each is an active Aox protein. The LeAox1b protein was shown to have altered regulatory properties due to the substitution of a Ser for the highly conserved Cys(I) residue. LeAox1b could not form inactive disulfide-linked dimers and was activated by succinate instead of pyruvate. This is the first example of a dicot species expressing a natural Cys(I)/Ser isoform. The implications of the existence and expression of such Aox isoforms is discussed in the light of the hypothesised role for Aox in plant metabolism.
Collapse
Affiliation(s)
- Ruth C Holtzapffel
- Plant Molecular Biology Group, Biochemistry and Molecular Biology, School of Biomedical and Chemical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley 6009, WA, Australia
| | | | | | | | | | | |
Collapse
|
33
|
McDonald AE, Sieger SM, Vanlerberghe GC. Methods and approaches to study plant mitochondrial alternative oxidase. PHYSIOLOGIA PLANTARUM 2002; 116:135-143. [PMID: 12354188 DOI: 10.1034/j.1399-3054.2002.1160201.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The alternative oxidase is a non-proton motive 'alternative' to electron transport through the cytochrome pathway. Despite its wasteful nature in terms of energy conservation, the pathway is likely present throughout the plant kingdom and appears to be expressed in most plant tissues. A small alternative oxidase gene family exists, the members of which are differentially expressed in response to environmental, developmental and other cell signals. The alternative oxidase enzyme possesses tight biochemical regulatory properties that determine its ability to compete with the cytochrome pathway for electrons. Studies show that alternative oxidase can be a prominent component of total respiration in important crop species. All these characteristics suggest this pathway plays an important role in metabolism and/or other aspects of cell physiology. This brief review is an introduction to experimental methods and approaches applicable to different areas of alternative oxidase research. We hope it provides a framework for further investigation of this fascinating component of primary plant metabolism.
Collapse
Affiliation(s)
- Allison E. McDonald
- Division of Life Sciences and Department of Botany, University of Toronto at Scarborough, 1265 Military Trail, Scarborough, ON M1C 1A4, Canada
| | | | | |
Collapse
|
34
|
Abe F, Saito K, Miura K, Toriyama K. A single nucleotide polymorphism in the alternative oxidase gene among rice varieties differing in low temperature tolerance. FEBS Lett 2002; 527:181-5. [PMID: 12220657 DOI: 10.1016/s0014-5793(02)03218-0] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Alternative oxidase (AOX) is encoded in a multigene family, and multiple isoforms have been observed in various plant species. We found for the first time an allelic variation in the same AOX locus. On SDS-gel blots of callus protein of rice (Oryza sativa L.), varieties without the QTL for low temperature tolerance showed a 32-kDa AOX band, whereas those with the QTL showed a 34-kDa band. The variation was attributed to the substitution of Lys(71) for Asn(71) caused by a single nucleotide polymorphism between alleles of OsAOX1a, and was tightly linked to the presence of the QTL.
Collapse
Affiliation(s)
- Fumitaka Abe
- Laboratory of Plant Breeding and Genetics, Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, 981-8555, Sendai, Japan
| | | | | | | |
Collapse
|
35
|
Considine MJ, Holtzapffel RC, Day DA, Whelan J, Millar AH. Molecular distinction between alternative oxidase from monocots and dicots. PLANT PHYSIOLOGY 2002; 129:949-53. [PMID: 12114550 PMCID: PMC1540239 DOI: 10.1104/pp.004150] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Affiliation(s)
- Michael James Considine
- Plant Molecular Biology Group, School of Biomedical and Chemical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
| | | | | | | | | |
Collapse
|
36
|
Avila-Adame C, Köller W. Disruption of the alternative oxidase gene in Magnaporthe grisea and its impact on host infection. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2002; 15:493-500. [PMID: 12036280 DOI: 10.1094/mpmi.2002.15.5.493] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Plants and numerous fungi including Magnaporthe grisea protect mitochondria from interference by respiration inhibitors by expressing alternative oxidase, the enzymatic core of alternative respiration. The alternative oxidase gene AOXMg of M. grisea was disrupted. Several lines of evidence suggested that the disruption of AOXMg was sufficient to completely curb the expression of alternative respiration. In the infection of barley leaves, several AOXMg-minus and, thus, alternative respiration-deficient mutants of M. grisea retained their pathogenicity without significant impairment of virulence. However, differences between the wild-type strain and an AOXMg-minus mutant were apparent under oxidative stress conditions generated by the treatment of infected barley leaves with the commercial respiration inhibitor azoxystrobin. Symptom development was effectively suppressed on leaves infected with the alternative respiration-deficient mutant, while lesions on leaves infected with the wild-type strain continued to develop at much higher inhibitor doses. However, respective lesions rarely developed to the stage of full maturity. The results did not conform to a previous model implying that expression of alternative respiration is silenced during pathogenesis by the presence of constitutive plant antioxidants. Rather, alternative respiration provided protection from azoxystrobin during both saprophytic and infectious stages of the pathogen. The nature of similar oxidative stress conditions in the ecology of M. grisea remains an open question.
Collapse
Affiliation(s)
- Cruz Avila-Adame
- Department of Plant Pathology, Cornell University, New York State Agricultural Experiment Station, Geneva 14456, USA
| | | |
Collapse
|
37
|
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]
|
38
|
Considine MJ, Daley DO, Whelan J. The expression of alternative oxidase and uncoupling protein during fruit ripening in mango. PLANT PHYSIOLOGY 2001; 126:1619-29. [PMID: 11500560 PMCID: PMC117161 DOI: 10.1104/pp.126.4.1619] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2001] [Accepted: 05/07/2001] [Indexed: 05/19/2023]
Abstract
The expression of alternative oxidase (Aox) and uncoupling proteins (Ucp) was investigated during ripening in mango (Mangifera indica) and compared with the expression of peroxisomal thiolase, a previously described ripening marker in mango. The multigene family for the Aox in mango was expressed differentially during ripening. Abundance of Aox message and protein both peaked at the ripe stage. Expression of the single gene for the Ucp peaked at the turning stage and the protein abundance peaked at the ripe stage. Proteins of the cytochrome chain peaked at the mature stage of ripening. The pattern of protein accumulation suggested that increases in cytochrome chain components played an important role in facilitating the climacteric burst of respiration and that the Aox and Ucp may play a role in post-climacteric senescent processes. Because both message and protein for the Aox and Ucp increased in a similar pattern, it suggests that their expression is not controlled in a reciprocal manner but may be active simultaneously.
Collapse
Affiliation(s)
- M J Considine
- Department of Biochemistry, The University of Western Australia, Nedlands, Western Australia 6907, Australia
| | | | | |
Collapse
|
39
|
Millenaar FF, Gonzàlez-Meler MA, Fiorani F, Welschen R, Ribas-Carbo M, Siedow JN, Wagner AM, Lambers H. Regulation of alternative oxidase activity in six wild monocotyledonous species. An in vivo study at the whole root level. PLANT PHYSIOLOGY 2001; 126:376-87. [PMID: 11351100 PMCID: PMC102311 DOI: 10.1104/pp.126.1.376] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2000] [Revised: 10/20/2000] [Accepted: 01/23/2001] [Indexed: 05/17/2023]
Abstract
The activity of the alternative pathway is affected by a number of factors, including the level and reduction state of the alternative oxidase (AOX) protein, and the reduction state of the ubiquinone pool. To investigate the significance of these factors for the rate of alternative respiration in vivo, we studied root respiration of six wild monocotyledonous grass species that were grown under identical controlled conditions. The activity of the alternative pathway was determined using the oxygen isotope fractionation technique. In all species, the AOX protein was invariably in its reduced (high activity) state. There was no correlation between AOX activity and AOX protein concentration, ubiquinone (total, reduced, or oxidized) concentration, or the reduction state of the ubiquinone pool. However, when some of these factors are combined in a linear regression model, a good fit to AOX activity is obtained. The function of the AOX is still not fully understood. It is interesting that we found a positive correlation between the activity of the alternative pathway and relative growth rate; a possible explanation for this correlation is discussed. Inhibition of the AOX (with salicylhydroxamic acid) decreases respiration rates less than the activity present before inhibition (i.e. measured with the 18O-fractionation technique).
Collapse
Affiliation(s)
- F F Millenaar
- Plant Ecophysiology, Utrecht University, Sorbonnelaan 16, 3584 CA Utrecht, The Netherlands.
| | | | | | | | | | | | | | | |
Collapse
|
40
|
Lacomme C, Roby D. Identification of new early markers of the hypersensitive response in Arabidopsis thaliana(1). FEBS Lett 1999; 459:149-53. [PMID: 10518009 DOI: 10.1016/s0014-5793(99)01233-8] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
New molecular markers of the hypersensitive response (HR) of Arabidopsis thaliana to the bacterial pathogen Xanthomonas campestris pv. campestris (X.c.c.) have been identified by differential screening of a cDNA library constructed from suspension cells inoculated by an HR-inducing strain in the presence of cycloheximide. Seven families of genes (called Athsr) have been isolated, show similarities to voltage-dependent anion channels (VDAC) and alternative oxidases, or are novel proteins. Athsr genes have shown to be specifically or preferentially expressed during the HR. These data suggest that Athsr genes might be involved in early events conditioning the establishment of the HR.
Collapse
Affiliation(s)
- C Lacomme
- Scottish Crop Research Institute, Department of Virology, Invergowrie, Dundee, UK
| | | |
Collapse
|
41
|
Simons BH, Millenaar FF, Mulder L, Van Loon LC, Lambers H. Enhanced expression and activation of the alternative oxidase during infection of Arabidopsis with Pseudomonas syringae pv tomato. PLANT PHYSIOLOGY 1999; 120:529-38. [PMID: 10364404 PMCID: PMC59291 DOI: 10.1104/pp.120.2.529] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/1998] [Accepted: 02/23/1999] [Indexed: 05/18/2023]
Abstract
Cyanide-resistant ("alternative") respiration was studied in Arabidopsis during incompatible and compatible infection with Pseudomonas syringae pv tomato DC3000. Total leaf respiration increased as the leaves became necrotic, as did the cyanide-resistant component that was sensitive to salicylhydroxamic acid. Infiltration of leaves with an avirulent strain rapidly induced alternative oxidase (AOX) mRNA, whereas the increase was delayed in the compatible combination. The increase in mRNA correlated with the increase in AOX protein. Increased expression was confined to the infected leaves, in contrast to the pathogenesis-related protein-1, which was induced systemically. Virtually all of the AOX protein was in the reduced (high-activity) form. Using transgenic NahG and mutant npr1-1 and etr1-1 plants, we established that the rapid induction of the AOX was associated with necrosis and that ethylene, but not salicylic acid, was required for its induction. Increased pyruvate levels in the infected leaves suggested that increased substrate levels were respired through the alternative pathway; however, in the control leaves and the infected leaves, respiration was not inhibited by salicylhydroxamic acid alone. Increased respiration appeared to be associated primarily with symptom expression rather than resistance reactions.
Collapse
Affiliation(s)
- B H Simons
- Graduate School of Functional Ecology, Department of Plant Ecology and Evolutionary Biology, Section of Plant Pathology, Utrecht University, The Netherlands
| | | | | | | | | |
Collapse
|
42
|
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.
Collapse
Affiliation(s)
- P M Finnegan
- Division of Biochemistry and Molecular Biology, Faculty of Science, The Australian National University, Canberra, ACT.
| | | | | |
Collapse
|
43
|
McCabe TC, Finnegan PM, Day DA, Whelan J. Differential expression of alternative oxidase genes in soybean cotyledons during postgerminative development. PLANT PHYSIOLOGY 1998; 118:675-82. [PMID: 9765553 PMCID: PMC34843 DOI: 10.1104/pp.118.2.675] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/1998] [Accepted: 07/21/1998] [Indexed: 05/18/2023]
Abstract
The expression of the alternative oxidase (AOX) was investigated during cotyledon development in soybean (Glycine max [L.] Merr.) seedlings. The total amount of AOX protein increased throughout development, not just in earlier stages as previously thought, and was correlated with the increase in capacity of the alternative pathway. Each AOX isoform (AOX1, AOX2, and AOX3) showed a different developmental trend in mRNA abundance, such that the increase in AOX protein and capacity appears to involve a shift in gene expression from AOX2 to AOX3. As the cotyledons aged, the size of the mitochondrial ubiquinone pool decreased. We discuss how this and other factors may affect the alternative pathway activity that results from the developmental regulation of AOX expression.
Collapse
Affiliation(s)
- TC McCabe
- Department of Biochemistry, The University of Western Australia, Nedlands, Perth, WA 6907, Australia (T.C.M., J.W.)
| | | | | | | |
Collapse
|
44
|
Van Hellemond JJ, Simons B, Millenaar FF, Tielens AG. A gene encoding the plant-like alternative oxidase is present in Phytomonas but absent in Leishmania spp. J Eukaryot Microbiol 1998; 45:426-30. [PMID: 9703678 DOI: 10.1111/j.1550-7408.1998.tb05094.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The constituents of the respiratory chain are believed to differ among the trypanosomatids; bloodstream stages of African trypanosomes and Phytomonas promastigotes oxidize ubiquinol by a ubiquinol:oxygen oxidoreductase, also known as alternative oxidase, whereas Leishmania spp. oxidize ubiquinol via a classic cytochrome-containing respiratory chain. The molecular basis for this elementary difference in ubiquinol oxidation by the mitochondrial electron-transport chain in distinct trypanosomatids was investigated. The presence of a gene encoding the plant-like alternative oxidase could be demonstrated in Phytomonas and Trypanosoma brucei, trypanosomatids that are known to contain alternative oxidase activity. Our results further demonstrated that Leishmania spp. lack a gene encoding the plant-like alternative oxidase, and therefore, all stages of Leishmania spp. will lack the alternative oxidase protein. The observed fundamental differences between the respiratory chains of distinct members of the trypanosomatid family are thus caused by the presence or absence of a gene encoding the plant-like alternative oxidase.
Collapse
Affiliation(s)
- J J Van Hellemond
- Laboratory of Veterinary Biochemistry, Utrecht University, The Netherlands
| | | | | | | |
Collapse
|
45
|
Sluse FE, Jarmuszkiewicz W. Alternative oxidase in the branched mitochondrial respiratory network: an overview on structure, function, regulation, and role. Braz J Med Biol Res 1998; 31:733-47. [PMID: 9698817 DOI: 10.1590/s0100-879x1998000600003] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Plants and some other organisms including protists possess a complex branched respiratory network in their mitochondria. Some pathways of this network are not energy-conserving and allow sites of energy conservation to be bypassed, leading to a decrease of the energy yield in the cells. It is a challenge to understand the regulation of the partitioning of electrons between the various energy-dissipating and -conserving pathways. This review is focused on the oxidase side of the respiratory chain that presents a cyanide-resistant energy-dissipating alternative oxidase (AOX) besides the cytochrome pathway. The known structural properties of AOX are described including transmembrane topology, dimerization, and active sites. Regulation of the alternative oxidase activity is presented in detail because of its complexity. The alternative oxidase activity is dependent on substrate availability: total ubiquinone concentration and its redox state in the membrane and O2 concentration in the cell. The alternative oxidase activity can be long-term regulated (gene expression) or short-term (post-translational modification, allosteric activation) regulated. Electron distribution (partitioning) between the alternative and cytochrome pathways during steady-state respiration is a crucial measurement to quantitatively analyze the effects of the various levels of regulation of the alternative oxidase. Three approaches are described with their specific domain of application and limitations: kinetic approach, oxygen isotope differential discrimination, and ADP/O method (thermokinetic approach). Lastly, the role of the alternative oxidase in non-thermogenic tissues is discussed in relation to the energy metabolism balance of the cell (supply in reducing equivalents/demand in energy and carbon) and with harmful reactive oxygen species formation.
Collapse
Affiliation(s)
- F E Sluse
- Laboratory of Bioenergetics, University of Liege, Belgium.
| | | |
Collapse
|
46
|
Berthold DA. Isolation of mutants of the Arabidopsis thaliana alternative oxidase (ubiquinol:oxygen oxidoreductase) resistant to salicylhydroxamic acid. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1364:73-83. [PMID: 9554960 DOI: 10.1016/s0005-2728(98)00015-2] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The plant-type ubiquinol:oxygen oxidoreductase, commonly called the alternative oxidase, is a respiratory enzyme thought to contain non-heme iron at its active site. To explore the structure of the enzyme by identifying amino acids involved in inhibitor-binding, a library of random mutants of the Arabidopsis thaliana alternative oxidase was constructed using error-prone polymerase chain reaction and expressed in the heme-deficient Escherichia coli SASX41B. Selection for resistance to salicylhydroxamic acid (SHAM) resulted in the recovery of four mutations. Three of these, F215L, M219I, and M219V, confer a small, but measurable resistance to SHAM of between 1.4- and 1.7-fold relative to the wild type alternative oxidase. These changes are located in a putative amphipathic helix following the second transmembrane helix. The fourth mutation, G303E, is found three residues from the C-terminus of the protein, and results in 4. 6-fold resistance to SHAM. None of the mutations have any effect on the sensitivity of the alternative oxidase to propyl gallate. The identification of distant residues involved in SHAM resistance suggests that the poorly conserved C-terminal region is in spatial proximity to the amphipathic helix, and thus located in the vicinity of the iron-binding motif.
Collapse
Affiliation(s)
- D A Berthold
- Department of Plant and Microbial Biology, 111 Koshland Hall, University of California, Berkeley, CA 94720-3102, USA.
| |
Collapse
|
47
|
Jarmuszkiewicz W, Wagner AM, Wagner MJ, Hryniewiecka L. Immunological identification of the alternative oxidase of Acanthamoeba castellanii mitochondria. FEBS Lett 1997; 411:110-4. [PMID: 9247153 DOI: 10.1016/s0014-5793(97)00676-5] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Mitochondria of the protozoa Acanthamoeba castellanii possess a cyanide-insensitive oxidase cross-reacting with monoclonal antibodies raised against the plant alternative oxidase. Immunoblotting revealed three monomeric forms (38, 35, and 32 kDa) and very low amounts of a single 65 kDa dimeric form. Cross-linking studies suggest that while in plants the alternative oxidase occurs as a dimer, in amoeba it functions as a monomer. Immunologically detectable protein levels change with the age of amoeba cell culture. Increased amounts of the 35 kDa protein are accompanied by an increase in the activity of cyanide-resistant respiration.
Collapse
Affiliation(s)
- W Jarmuszkiewicz
- Department of Bioenergetics, Institute of Molecular Biology and Biotechnology, Poznan University, Poland.
| | | | | | | |
Collapse
|
48
|
Abstract
Plants, some fungi, and protists contain a cyanide-resistant, alternative mitochondrial respiratory pathway. This pathway branches at the ubiquinone pool and consists of an alternative oxidase encoded by the nuclear gene Aox1. Alternative pathway respiration is only linked to proton translocation at Complex 1 (NADH dehydrogenase). Alternative oxidase expression is influenced by stress stimuli-cold, oxidative stress, pathogen attack-and by factors constricting electron flow through the cytochrome pathway of respiration. Control is exerted at the levels of gene expression and in response to the availability of carbon and reducing potential. Posttranslational control involves reversible covalent modification of the alternative oxidase and activation by specific carbon metabolites. This dynamic system of coarse and fine control may function to balance upstream respiratory carbon metabolism and downstream electron transport when these coupled processes become imbalanced as a result of changes in the supply of, or demand for, carbon, reducing power, and ATP.
Collapse
Affiliation(s)
- Greg C. Vanlerberghe
- Department of Botany and Division of Life Science, University of Toronto at Scarborough, 1265 Military Trail, Scarborough, Ontario M1C 1A4, Canada, Department of Energy Plant Research Laboratory and Biochemistry Department, Michigan State University, East Lansing, Michigan 48824
| | | |
Collapse
|
49
|
Gutierres S, Sabar M, Lelandais C, Chetrit P, Diolez P, Degand H, Boutry M, Vedel F, de Kouchkovsky Y, De Paepe R. Lack of mitochondrial and nuclear-encoded subunits of complex I and alteration of the respiratory chain in Nicotiana sylvestris mitochondrial deletion mutants. Proc Natl Acad Sci U S A 1997; 94:3436-41. [PMID: 9096412 PMCID: PMC20388 DOI: 10.1073/pnas.94.7.3436] [Citation(s) in RCA: 146] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/1996] [Accepted: 01/06/1997] [Indexed: 02/04/2023] Open
Abstract
We previously have shown that Nicotiana sylvestris cytoplasmic male sterile (CMS) mutants I and II present large mtDNA deletions and that the NAD7 subunit of complex I (the main dehydrogenase of the mitochondrial respiratory chain) is absent in CMS I. Here, we show that, despite a large difference in size in the mtDNA deletion, CMS I and II display similar alterations. Both have an impaired development from germination to flowering, with partial male sterility that becomes complete under low light. Besides NAD7, two other complex I subunits are missing (NAD9 and the nucleus-encoded, 38-kDa subunit), identified on two-dimensional patterns of mitochondrial proteins. Mitochondria isolated from CMS leaves showed altered respiration. Although their succinate oxidation through complex II was close to that of the wild type, oxidation of glycine, a priority substrate of plant mitochondria, was significantly reduced. The remaining activity was much less sensitive to rotenone, indicating the breakdown of Complex I activity. Oxidation of exogenous NADH (coupled to proton gradient generation and partly sensitive to rotenone) was strongly increased. These results suggest respiratory compensation mechanisms involving additional NADH dehydrogenases to complex I. Finally, the capacity of the cyanide-resistant alternative oxidase pathway was enhanced in CMS, and higher amounts of enzyme were evidenced by immunodetection.
Collapse
Affiliation(s)
- S Gutierres
- Institut de Biotechnologie des Plantes, Centre National de la Recherche Scientifique (Unité de Recherche Associée 1128), Université Paris-Sud, Orsay, France
| | | | | | | | | | | | | | | | | | | |
Collapse
|
50
|
Chaudhuri M, Hill GC. Cloning, sequencing, and functional activity of the Trypanosoma brucei brucei alternative oxidase. Mol Biochem Parasitol 1996; 83:125-9. [PMID: 9010848 DOI: 10.1016/s0166-6851(96)02754-5] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- M Chaudhuri
- Division of Biomedical Sciences, Meharry Medical College, Nashville, TN 37208-3599, USA
| | | |
Collapse
|