1
|
Huang Q, Zhao Z, Liu X, Yuan X, Zhao R, Niu Q, Li C, Liu Y, Wang D, Yu T, Yi H, Yang C, Rong T, Cao M. Maize plastid terminal oxidase (ZmPTOX) regulates the color formation of leaf and kernel by modulating plastid development. J Genet Genomics 2024:S1673-8527(24)00121-8. [PMID: 38815650 DOI: 10.1016/j.jgg.2024.05.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2024] [Revised: 05/20/2024] [Accepted: 05/21/2024] [Indexed: 06/01/2024]
Affiliation(s)
- Qiang Huang
- State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China, Maize Research Institute, Sichuan Agricultural University, Chengdu, Sichuan 611130, China; Irradiation Preservation Key Laboratory of Sichuan Province, Sichuan Institute of Atomic Energy, Chengdu, Sichuan 610101, China
| | - Zhuofan Zhao
- State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China, Maize Research Institute, Sichuan Agricultural University, Chengdu, Sichuan 611130, China; Chengdu University of Technology, Chengdu, Sichuan 610051, China
| | - Xiaowei Liu
- State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China, Maize Research Institute, Sichuan Agricultural University, Chengdu, Sichuan 611130, China
| | - Xin Yuan
- State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China, Maize Research Institute, Sichuan Agricultural University, Chengdu, Sichuan 611130, China
| | - Ruiqing Zhao
- State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China, Maize Research Institute, Sichuan Agricultural University, Chengdu, Sichuan 611130, China
| | - Qunkai Niu
- State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China, Maize Research Institute, Sichuan Agricultural University, Chengdu, Sichuan 611130, China; Chengdu Agricultural College, Chengdu, Sichuan 611130, China
| | - Chuan Li
- State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China, Maize Research Institute, Sichuan Agricultural University, Chengdu, Sichuan 611130, China
| | - Yusheng Liu
- Irradiation Preservation Key Laboratory of Sichuan Province, Sichuan Institute of Atomic Energy, Chengdu, Sichuan 610101, China
| | - Danfeng Wang
- College of Biology Pharmacy and Food Engineering, Shangluo University, Shangluo, Shanxi 726000, China
| | - Tao Yu
- State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China, Maize Research Institute, Sichuan Agricultural University, Chengdu, Sichuan 611130, China
| | - Hongyang Yi
- State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China, Maize Research Institute, Sichuan Agricultural University, Chengdu, Sichuan 611130, China
| | - Chengming Yang
- Irradiation Preservation Key Laboratory of Sichuan Province, Sichuan Institute of Atomic Energy, Chengdu, Sichuan 610101, China
| | - Tingzhao Rong
- State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China, Maize Research Institute, Sichuan Agricultural University, Chengdu, Sichuan 611130, China; Irradiation Preservation Key Laboratory of Sichuan Province, Sichuan Institute of Atomic Energy, Chengdu, Sichuan 610101, China
| | - Moju Cao
- State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China, Maize Research Institute, Sichuan Agricultural University, Chengdu, Sichuan 611130, China; Irradiation Preservation Key Laboratory of Sichuan Province, Sichuan Institute of Atomic Energy, Chengdu, Sichuan 610101, China.
| |
Collapse
|
2
|
Li J, Yang S, Wu Y, Wang R, Liu Y, Liu J, Ye Z, Tang R, Whiteway M, Lv Q, Yan L. Alternative Oxidase: From Molecule and Function to Future Inhibitors. ACS OMEGA 2024; 9:12478-12499. [PMID: 38524433 PMCID: PMC10955580 DOI: 10.1021/acsomega.3c09339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 01/31/2024] [Accepted: 02/07/2024] [Indexed: 03/26/2024]
Abstract
In the respiratory chain of the majority of aerobic organisms, the enzyme alternative oxidase (AOX) functions as the terminal oxidase and has important roles in maintaining metabolic and signaling homeostasis in mitochondria. AOX endows the respiratory system with flexibility in the coupling among the carbon metabolism pathway, electron transport chain (ETC) activity, and ATP turnover. AOX allows electrons to bypass the main cytochrome pathway to restrict the generation of reactive oxygen species (ROS). The inhibition of AOX leads to oxidative damage and contributes to the loss of adaptability and viability in some pathogenic organisms. Although AOXs have recently been identified in several organisms, crystal structures and major functions still need to be explored. Recent work on the trypanosome alternative oxidase has provided a crystal structure of an AOX protein, which contributes to the structure-activity relationship of the inhibitors of AOX. Here, we review the current knowledge on the development, structure, and properties of AOXs, as well as their roles and mechanisms in plants, animals, algae, protists, fungi, and bacteria, with a special emphasis on the development of AOX inhibitors, which will improve the understanding of respiratory regulation in many organisms and provide references for subsequent studies of AOX-targeted inhibitors.
Collapse
Affiliation(s)
- Jiye Li
- School
of Pharmacy, Naval Medical University, Shanghai 200433, China
- Institute
of Medicinal Biotechnology, Chinese Academy
of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Shiyun Yang
- School
of Pharmacy, Naval Medical University, Shanghai 200433, China
| | - Yujie Wu
- School
of Pharmacy, Naval Medical University, Shanghai 200433, China
| | - Ruina Wang
- School
of Pharmacy, Naval Medical University, Shanghai 200433, China
| | - Yu Liu
- School
of Pharmacy, Naval Medical University, Shanghai 200433, China
| | - Jiacun Liu
- School
of Pharmacy, Naval Medical University, Shanghai 200433, China
| | - Zi Ye
- School
of Pharmacy, Naval Medical University, Shanghai 200433, China
| | - Renjie Tang
- Beijing
South Medical District of Chinese PLA General Hospital, Beijing 100072, China
| | - Malcolm Whiteway
- Department
of Biology, Concordia University, Montreal, H4B 1R6 Quebec, Canada
| | - Quanzhen Lv
- School
of Pharmacy, Naval Medical University, Shanghai 200433, China
- Basic
Medicine Innovation Center for Fungal Infectious Diseases, (Naval Medical University), Ministry of Education, Shanghai 200433, China
- Key
Laboratory of Biosafety Defense (Naval Medical University), Ministry
of Education, Shanghai 200433, China
- Shanghai
Key Laboratory of Medical Biodefense, Shanghai 200433, China
| | - Lan Yan
- School
of Pharmacy, Naval Medical University, Shanghai 200433, China
- Basic
Medicine Innovation Center for Fungal Infectious Diseases, (Naval Medical University), Ministry of Education, Shanghai 200433, China
- Key
Laboratory of Biosafety Defense (Naval Medical University), Ministry
of Education, Shanghai 200433, China
- Shanghai
Key Laboratory of Medical Biodefense, Shanghai 200433, China
| |
Collapse
|
3
|
El-Khoury R, Rak M, Bénit P, Jacobs HT, Rustin P. Cyanide resistant respiration and the alternative oxidase pathway: A journey from plants to mammals. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148567. [PMID: 35500614 DOI: 10.1016/j.bbabio.2022.148567] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 04/06/2022] [Accepted: 04/18/2022] [Indexed: 12/19/2022]
Abstract
In a large number of organisms covering all phyla, the mitochondrial respiratory chain harbors, in addition to the conventional elements, auxiliary proteins that confer adaptive metabolic plasticity. The alternative oxidase (AOX) represents one of the most studied auxiliary proteins, initially identified in plants. In contrast to the standard respiratory chain, the AOX mediates a thermogenic cyanide-resistant respiration; a phenomenon that has been of great interest for over 2 centuries in that energy is not conserved when electrons flow through it. Here we summarize centuries of studies starting from the early observations of thermogenicity in plants and the identification of cyanide resistant respiration, to the fascinating discovery of the AOX and its current applications in animals under normal and pathological conditions.
Collapse
Affiliation(s)
- Riyad El-Khoury
- American University of Beirut Medical Center, Pathology and Laboratory Medicine Department, Cairo Street, Hamra, Beirut, Lebanon
| | - Malgorzata Rak
- Université Paris Cité, Inserm, Maladies neurodéveloppementales et neurovasculaires, F-75019 Paris, France
| | - Paule Bénit
- Université Paris Cité, Inserm, Maladies neurodéveloppementales et neurovasculaires, F-75019 Paris, France
| | - Howard T Jacobs
- Faculty of Medicine and Health Technology, FI-33014, Tampere University, Finland; Institute of Biotechnology, University of Helsinki, Helsinki, Finland.
| | - Pierre Rustin
- Université Paris Cité, Inserm, Maladies neurodéveloppementales et neurovasculaires, F-75019 Paris, France.
| |
Collapse
|
4
|
Targeting the alternative oxidase (AOX) for human health and food security, a pharmaceutical and agrochemical target or a rescue mechanism? Biochem J 2022; 479:1337-1359. [PMID: 35748702 PMCID: PMC9246349 DOI: 10.1042/bcj20180192] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 05/23/2022] [Accepted: 06/07/2022] [Indexed: 11/25/2022]
Abstract
Some of the most threatening human diseases are due to a blockage of the mitochondrial electron transport chain (ETC). In a variety of plants, fungi, and prokaryotes, there is a naturally evolved mechanism for such threats to viability, namely a bypassing of the blocked portion of the ETC by alternative enzymes of the respiratory chain. One such enzyme is the alternative oxidase (AOX). When AOX is expressed, it enables its host to survive life-threatening conditions or, as in parasites, to evade host defenses. In vertebrates, this mechanism has been lost during evolution. However, we and others have shown that transfer of AOX into the genome of the fruit fly and mouse results in a catalytically engaged AOX. This implies that not only is the AOX a promising target for combating human or agricultural pathogens but also a novel approach to elucidate disease mechanisms or, in several cases, potentially a therapeutic cure for human diseases. In this review, we highlight the varying functions of AOX in their natural hosts and upon xenotopic expression, and discuss the resulting need to develop species-specific AOX inhibitors.
Collapse
|
5
|
Møller IM, Rasmusson AG, Van Aken O. Plant mitochondria - past, present and future. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 108:912-959. [PMID: 34528296 DOI: 10.1111/tpj.15495] [Citation(s) in RCA: 78] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 09/02/2021] [Accepted: 09/06/2021] [Indexed: 06/13/2023]
Abstract
The study of plant mitochondria started in earnest around 1950 with the first isolations of mitochondria from animal and plant tissues. The first 35 years were spent establishing the basic properties of plant mitochondria and plant respiration using biochemical and physiological approaches. A number of unique properties (compared to mammalian mitochondria) were observed: (i) the ability to oxidize malate, glycine and cytosolic NAD(P)H at high rates; (ii) the partial insensitivity to rotenone, which turned out to be due to the presence of a second NADH dehydrogenase on the inner surface of the inner mitochondrial membrane in addition to the classical Complex I NADH dehydrogenase; and (iii) the partial insensitivity to cyanide, which turned out to be due to an alternative oxidase, which is also located on the inner surface of the inner mitochondrial membrane, in addition to the classical Complex IV, cytochrome oxidase. With the appearance of molecular biology methods around 1985, followed by genomics, further unique properties were discovered: (iv) plant mitochondrial DNA (mtDNA) is 10-600 times larger than the mammalian mtDNA, yet it only contains approximately 50% more genes; (v) plant mtDNA has kept the standard genetic code, and it has a low divergence rate with respect to point mutations, but a high recombinatorial activity; (vi) mitochondrial mRNA maturation includes a uniquely complex set of activities for processing, splicing and editing (at hundreds of sites); (vii) recombination in mtDNA creates novel reading frames that can produce male sterility; and (viii) plant mitochondria have a large proteome with 2000-3000 different proteins containing many unique proteins such as 200-300 pentatricopeptide repeat proteins. We describe the present and fairly detailed picture of the structure and function of plant mitochondria and how the unique properties make their metabolism more flexible allowing them to be involved in many diverse processes in the plant cell, such as photosynthesis, photorespiration, CAM and C4 metabolism, heat production, temperature control, stress resistance mechanisms, programmed cell death and genomic evolution. However, it is still a challenge to understand how the regulation of metabolism and mtDNA expression works at the cellular level and how retrograde signaling from the mitochondria coordinates all those processes.
Collapse
Affiliation(s)
- Ian Max Møller
- Department of Molecular Biology and Genetics, Aarhus University, Forsøgsvej 1, DK-4200, Slagelse, Denmark
| | | | | |
Collapse
|
6
|
Boes DM, Godoy-Hernandez A, McMillan DGG. Peripheral Membrane Proteins: Promising Therapeutic Targets across Domains of Life. MEMBRANES 2021; 11:membranes11050346. [PMID: 34066904 PMCID: PMC8151925 DOI: 10.3390/membranes11050346] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 04/28/2021] [Accepted: 05/05/2021] [Indexed: 11/16/2022]
Abstract
Membrane proteins can be classified into two main categories—integral and peripheral membrane proteins—depending on the nature of their membrane interaction. Peripheral membrane proteins are highly unique amphipathic proteins that interact with the membrane indirectly, using electrostatic or hydrophobic interactions, or directly, using hydrophobic tails or GPI-anchors. The nature of this interaction not only influences the location of the protein in the cell, but also the function. In addition to their unique relationship with the cell membrane, peripheral membrane proteins often play a key role in the development of human diseases such as African sleeping sickness, cancer, and atherosclerosis. This review will discuss the membrane interaction and role of periplasmic nitrate reductase, CymA, cytochrome c, alkaline phosphatase, ecto-5’-nucleotidase, acetylcholinesterase, alternative oxidase, type-II NADH dehydrogenase, and dihydroorotate dehydrogenase in certain diseases. The study of these proteins will give new insights into their function and structure, and may ultimately lead to ground-breaking advances in the treatment of severe diseases.
Collapse
Affiliation(s)
- Deborah M. Boes
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, NL-2629 HZ Delft, The Netherlands; (D.M.B.); (A.G.-H.)
| | - Albert Godoy-Hernandez
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, NL-2629 HZ Delft, The Netherlands; (D.M.B.); (A.G.-H.)
| | - Duncan G. G. McMillan
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, NL-2629 HZ Delft, The Netherlands; (D.M.B.); (A.G.-H.)
- School of Fundamental Sciences, Massey University, Palmerston North, Private Bag 11 222, New Zealand
- Correspondence:
| |
Collapse
|
7
|
Molecular characterization and gene expression modulation of the alternative oxidase in a scuticociliate parasite by hypoxia and mitochondrial respiration inhibitors. Sci Rep 2020; 10:11880. [PMID: 32681023 PMCID: PMC7367826 DOI: 10.1038/s41598-020-68791-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 07/01/2020] [Indexed: 12/26/2022] Open
Abstract
Philasterides dicentrarchi is a marine benthic microaerophilic scuticociliate and an opportunistic endoparasite that can infect and cause high mortalities in cultured turbot (Scophthalmus maximus). In addition to a cytochrome pathway (CP), the ciliate can use a cyanide-insensitive respiratory pathway, which indicates the existence of an alternative oxidase (AOX) in the mitochondrion. Although AOX activity has been described in P. dicentrarchi, based on functional assay results, genetic evidence of the presence of AOX in the ciliate has not previously been reported. In this study, we conducted genomic and transcriptomic analysis of the ciliate and identified the AOX gene and its corresponding mRNA. The AOX gene (size 1,106 bp) contains four exons and three introns that generate an open reading frame of 915 bp and a protein with a predicted molecular weight of 35.6 kDa. The amino acid (aa) sequence of the AOX includes an import signal peptide targeting the mitochondria and the protein is associated with the inner membrane of the mitochondria. Bioinformatic analysis predicted that the peptide is a homodimeric glycoprotein, although monomeric forms may also appear under native conditions, with EXXH motifs associated with the diiron active centers. The aa sequences of the AOX of different P. dicentrarchi isolates are highly conserved and phylogenetically closely related to AOXs of other ciliate species, especially scuticociliates. AOX expression increased significantly during infection in the host and after the addition of CP inhibitors. This confirms the important physiological roles of AOX in respiration under conditions of low levels of O2 and in protecting against oxidative stress generated during infection in the host.
Collapse
|
8
|
Kumari A, Pathak PK, Bulle M, Igamberdiev AU, Gupta KJ. Alternative oxidase is an important player in the regulation of nitric oxide levels under normoxic and hypoxic conditions in plants. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:4345-4354. [PMID: 30968134 DOI: 10.1093/jxb/erz160] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 03/29/2019] [Indexed: 05/03/2023]
Abstract
Plant mitochondria possess two different pathways for electron transport from ubiquinol: the cytochrome pathway and the alternative oxidase (AOX) pathway. The AOX pathway plays an important role in stress tolerance and is induced by various metabolites and signals. Previously, several lines of evidence indicated that the AOX pathway prevents overproduction of superoxide and other reactive oxygen species. More recent evidence suggests that AOX also plays a role in regulation of nitric oxide (NO) production and signalling. The AOX pathway is induced under low phosphate, hypoxia, pathogen infections, and elicitor treatments. The induction of AOX under aerobic conditions in response to various stresses can reduce electron transfer through complexes III and IV and thus prevents the leakage of electrons to nitrite and the subsequent accumulation of NO. Excess NO under various stresses can inhibit complex IV; thus, the AOX pathway minimizes nitrite-dependent NO synthesis that would arise from enhanced electron leakage in the cytochrome pathway. By preventing NO generation, AOX can reduce peroxynitrite formation and tyrosine nitration. In contrast to its function under normoxia, AOX has a specific role under hypoxia, where AOX can facilitate nitrite-dependent NO production. This reaction drives the phytoglobin-NO cycle to increase energy efficiency under hypoxia.
Collapse
Affiliation(s)
- Aprajita Kumari
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, Delhi, India
| | - Pradeep Kumar Pathak
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, Delhi, India
| | - Mallesham Bulle
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, Delhi, India
| | - Abir U Igamberdiev
- Department of Biology, Memorial University of Newfoundland, St. John's, NL, Canada
| | | |
Collapse
|
9
|
Brzezowski P, Ksas B, Havaux M, Grimm B, Chazaux M, Peltier G, Johnson X, Alric J. The function of PROTOPORPHYRINOGEN IX OXIDASE in chlorophyll biosynthesis requires oxidised plastoquinone in Chlamydomonas reinhardtii. Commun Biol 2019; 2:159. [PMID: 31069268 PMCID: PMC6499784 DOI: 10.1038/s42003-019-0395-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 03/20/2019] [Indexed: 12/23/2022] Open
Abstract
In the last common enzymatic step of tetrapyrrole biosynthesis, prior to the branching point leading to the biosynthesis of heme and chlorophyll, protoporphyrinogen IX (Protogen) is oxidised to protoporphyrin IX (Proto) by protoporphyrinogen IX oxidase (PPX). The absence of thylakoid-localised plastid terminal oxidase 2 (PTOX2) and cytochrome b6f complex in the ptox2 petB mutant, results in almost complete reduction of the plastoquinone pool (PQ pool) in light. Here we show that the lack of oxidised PQ impairs PPX function, leading to accumulation and subsequently uncontrolled oxidation of Protogen to non-metabolised Proto. Addition of 3(3,4-Dichlorophenyl)-1,1-dimethylurea (DCMU) prevents the over-reduction of the PQ pool in ptox2 petB and decreases Proto accumulation. This observation strongly indicates the need of oxidised PQ as the electron acceptor for the PPX reaction in Chlamydomonas reinhardtii. The PPX-PQ pool interaction is proposed to function as a feedback loop between photosynthetic electron transport and chlorophyll biosynthesis.
Collapse
Affiliation(s)
- Pawel Brzezowski
- Aix Marseille Université, CNRS, CEA, Institut de Biosciences et Biotechnologies Aix-Marseille, Laboratoire de Bioénergétique et Biotechnologie des Bactéries et Microalgues, CEA Cadarache, 13108 Saint-Paul-lez-Durance, France
- Humboldt-Universität zu Berlin, Institut für Biologie/Pflanzenphysiologie, 10115 Berlin, Germany
| | - Brigitte Ksas
- Aix Marseille Université, CNRS, CEA, Institut de Biosciences et Biotechnologies Aix-Marseille, Laboratoire d’Ecophysiologie Moléculaire des Plantes, CEA Cadarache, 13108 Saint-Paul-lez-Durance, France
| | - Michel Havaux
- Aix Marseille Université, CNRS, CEA, Institut de Biosciences et Biotechnologies Aix-Marseille, Laboratoire d’Ecophysiologie Moléculaire des Plantes, CEA Cadarache, 13108 Saint-Paul-lez-Durance, France
| | - Bernhard Grimm
- Humboldt-Universität zu Berlin, Institut für Biologie/Pflanzenphysiologie, 10115 Berlin, Germany
| | - Marie Chazaux
- Aix Marseille Université, CNRS, CEA, Institut de Biosciences et Biotechnologies Aix-Marseille, Laboratoire de Bioénergétique et Biotechnologie des Bactéries et Microalgues, CEA Cadarache, 13108 Saint-Paul-lez-Durance, France
| | - Gilles Peltier
- Aix Marseille Université, CNRS, CEA, Institut de Biosciences et Biotechnologies Aix-Marseille, Laboratoire de Bioénergétique et Biotechnologie des Bactéries et Microalgues, CEA Cadarache, 13108 Saint-Paul-lez-Durance, France
| | - Xenie Johnson
- Aix Marseille Université, CNRS, CEA, Institut de Biosciences et Biotechnologies Aix-Marseille, Laboratoire de Bioénergétique et Biotechnologie des Bactéries et Microalgues, CEA Cadarache, 13108 Saint-Paul-lez-Durance, France
| | - Jean Alric
- Aix Marseille Université, CNRS, CEA, Institut de Biosciences et Biotechnologies Aix-Marseille, Laboratoire de Bioénergétique et Biotechnologie des Bactéries et Microalgues, CEA Cadarache, 13108 Saint-Paul-lez-Durance, France
| |
Collapse
|
10
|
Ünlü ES, Ünüvar ÖC, Aydın M. Identification of alternative oxidase encoding genes in Caulerpa cylindracea by de novo RNA-Seq assembly analysis. Mar Genomics 2019; 46:41-48. [PMID: 30922784 DOI: 10.1016/j.margen.2019.03.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 02/06/2019] [Accepted: 03/06/2019] [Indexed: 11/29/2022]
Abstract
Alternative oxidases (AOX) are defined in plants, fungi and algae. The main function of AOX proteins has been described for electron flow through electron transport chain and regulation of mitochondrial retrograde signaling pathway. The roles of AOX proteins have been characterized in reproduction and resistance against oxidative stress, cold stress, starvation, and biotic attacks. Caulerpa cylindracea is an invasive marine green alga. Although the natural habitats of the species are Australia coasts, the impact of the invasion has been monitored through the Mediterranean Sea and the Aegean Sea. C. cylindracea species have advantages against others by showing higher resistance to stress conditions such as cold, starvation, pathogen attacks and by their capability of sexual and vegetative reproduction. Comparing the advantages of C. cylindracea over the niche and defined functional roles of mitochondrial AOX proteins, it is evident that AOX proteins are likely involved in developing those advantageous skills in C. cylindracea. However, there is limited data about biochemical and molecular mechanisms that take part in stress resistance and invasion characteristics. We aimed to identify mitochondrial alternative oxidase encoding genes in C. cylindracea while annotating whole transcriptome data for the species. Samples were collected from Seferihisar/İzmir. Transcriptome analysis from pooled RNA samples revealed 47,400 assembled contigs represented by 33,340 unigenes. Using standalone Blast analysis, we were able to identify two alternative oxidase encoding genes.
Collapse
Affiliation(s)
- Ercan Selçuk Ünlü
- Bolu Abant İzzet Baysal University, Faculty of Arts and Science, Department of Chemistry, Bolu 14280, Turkey.
| | - Ömer Can Ünüvar
- Bolu Abant İzzet Baysal University, Faculty of Arts and Science, Department of Chemistry, Bolu 14280, Turkey
| | - Meryem Aydın
- Bolu Abant İzzet Baysal University, Faculty of Arts and Science, Department of Chemistry, Bolu 14280, Turkey
| |
Collapse
|
11
|
Kaye Y, Huang W, Clowez S, Saroussi S, Idoine A, Sanz-Luque E, Grossman AR. The mitochondrial alternative oxidase from Chlamydomonas reinhardtii enables survival in high light. J Biol Chem 2018; 294:1380-1395. [PMID: 30510139 DOI: 10.1074/jbc.ra118.004667] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 10/24/2018] [Indexed: 01/07/2023] Open
Abstract
Photosynthetic organisms often experience extreme light conditions that can cause hyper-reduction of the chloroplast electron transport chain, resulting in oxidative damage. Accumulating evidence suggests that mitochondrial respiration and chloroplast photosynthesis are coupled when cells are absorbing high levels of excitation energy. This coupling helps protect the cells from hyper-reduction of photosynthetic electron carriers and diminishes the production of reactive oxygen species (ROS). To examine this cooperative protection, here we characterized Chlamydomonas reinhardtii mutants lacking the mitochondrial alternative terminal respiratory oxidases, CrAOX1 and CrAOX2. Using fluorescent fusion proteins, we experimentally demonstrated that both enzymes localize to mitochondria. We also observed that the mutant strains were more sensitive than WT cells to high light under mixotrophic and photoautotrophic conditions, with the aox1 strain being more sensitive than aox2 Additionally, the lack of CrAOX1 increased ROS accumulation, especially in very high light, and damaged the photosynthetic machinery, ultimately resulting in cell death. These findings indicate that the Chlamydomonas AOX proteins can participate in acclimation of C. reinhardtii cells to excess absorbed light energy. They suggest that when photosynthetic electron carriers are highly reduced, a chloroplast-mitochondria coupling allows safe dissipation of photosynthetically derived electrons via the reduction of O2 through AOX (especially AOX1)-dependent mitochondrial respiration.
Collapse
Affiliation(s)
- Yuval Kaye
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305.
| | - Weichao Huang
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305
| | - Sophie Clowez
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305
| | - Shai Saroussi
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305
| | - Adam Idoine
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305
| | - Emanuel Sanz-Luque
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305
| | - Arthur R Grossman
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305
| |
Collapse
|
12
|
Araújo Castro J, Gomes Ferreira MD, Santana Silva RJ, Andrade BS, Micheli F. Alternative oxidase (AOX) constitutes a small family of proteins in Citrus clementina and Citrus sinensis L. Osb. PLoS One 2017; 12:e0176878. [PMID: 28459876 PMCID: PMC5411082 DOI: 10.1371/journal.pone.0176878] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 04/18/2017] [Indexed: 11/18/2022] Open
Abstract
The alternative oxidase (AOX) protein is present in plants, fungi, protozoa and some invertebrates. It is involved in the mitochondrial respiratory chain, providing an alternative route for the transport of electrons, leading to the reduction of oxygen to form water. The present study aimed to characterize the family of AOX genes in mandarin (Citrus clementina) and sweet orange (Citrus sinensis) at nucleotide and protein levels, including promoter analysis, phylogenetic analysis and C. sinensis gene expression. This study also aimed to do the homology modeling of one AOX isoform (CcAOXd). Moreover, the molecular docking of the CcAOXd protein with the ubiquinone (UQ) was performed. Four AOX genes were identified in each citrus species. These genes have an open reading frame (ORF) ranging from 852 bp to 1150 bp and a number of exons ranging from 4 to 9. The 1500 bp-upstream region of each AOX gene contained regulatory cis-elements related to internal and external response factors. CsAOX genes showed a differential expression in citrus tissues. All AOX proteins were predicted to be located in mitochondria. They contained the conserved motifs LET, NERMHL, LEEEA and RADE-H as well as several putative post-translational modification sites. The CcAOXd protein was modeled by homology to the AOX of Trypanosona brucei (45% of identity). The 3-D structure of CcAOXd showed the presence of two hydrophobic helices that could be involved in the anchoring of the protein in the inner mitochondrial membrane. The active site of the protein is located in a hydrophobic environment deep inside the AOX structure and contains a diiron center. The molecular docking of CcAOXd with UQ showed that the binding site is a recessed pocket formed by the helices and submerged in the membrane. These data are important for future functional studies of citrus AOX genes and/or proteins, as well as for biotechnological approaches leading to AOX inhibition using UQ homologs.
Collapse
Affiliation(s)
- Jacqueline Araújo Castro
- Universidade Estadual de Santa Cruz (UESC), Centro de Biotecnologia e Genética (CBG), Ilhéus, Bahia, Brazil
- Instituto Federal de Educação, Ciência e Tecnologia Baiano (IFBaiano), Santa Inês, Bahia, Brazil
| | | | - Raner José Santana Silva
- Universidade Estadual de Santa Cruz (UESC), Centro de Biotecnologia e Genética (CBG), Ilhéus, Bahia, Brazil
| | - Bruno Silva Andrade
- Universidade Estadual Sudoeste da Bahia (UESB), Av. José Moreira Sobrinho, Jequié, Bahia, Brazil
| | - Fabienne Micheli
- Universidade Estadual de Santa Cruz (UESC), Centro de Biotecnologia e Genética (CBG), Ilhéus, Bahia, Brazil
- CIRAD, UMR AGAP, F-34398 Montpellier, France
- * E-mail:
| |
Collapse
|
13
|
Wang D, Fu A. The Plastid Terminal Oxidase is a Key Factor Balancing the Redox State of Thylakoid Membrane. Enzymes 2016; 40:143-171. [PMID: 27776780 DOI: 10.1016/bs.enz.2016.09.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/26/2023]
Abstract
Mitochondria possess oxygen-consuming respiratory electron transfer chains (RETCs), and the oxygen-evolving photosynthetic electron transfer chain (PETC) resides in chloroplasts. Evolutionarily mitochondria and chloroplasts are derived from ancient α-proteobacteria and cyanobacteria, respectively. However, cyanobacteria harbor both RETC and PETC on their thylakoid membranes. It is proposed that chloroplasts could possess a RETC on the thylakoid membrane, in addition to PETC. Identification of a plastid terminal oxidase (PTOX) in the chloroplast from the Arabidopsis variegation mutant immutans (im) demonstrated the presence of a RETC in chloroplasts, and the PTOX is the committed oxidase. PTOX is distantly related to the mitochondrial alternative oxidase (AOX), which is responsible for the CN-insensitive alternative RETC. Similar to AOX, an ubiquinol (UQH2) oxidase, PTOX is a plastoquinol (PQH2) oxidase on the chloroplast thylakoid membrane. Lack of PTOX, Arabidopsis im showed a light-dependent variegation phenotype; and mutant plants will not survive the mediocre light intensity during its early development stage. PTOX is very important for carotenoid biosynthesis, since the phytoene desaturation, a key step in the carotenoid biosynthesis, is blocked in the white sectors of Arabidopsis im mutant. PTOX is found to be a stress-related protein in numerous research instances. It is generally believed that PTOX can protect plants from various environmental stresses, especially high light stress. PTOX also plays significant roles in chloroplast development and plant morphogenesis. Global physiological roles played by PTOX could be a direct or indirect consequence of its PQH2 oxidase activity to maintain the PQ pool redox state on the thylakoid membrane. The PTOX-dependent chloroplast RETC (so-called chlororespiration) does not contribute significantly when chloroplast PETC is normally developed and functions well. However, PTOX-mediated RETC could be the major force to regulate the PQ pool redox balance in the darkness, under conditions of stress, in nonphotosynthetic plastids, especially in the early development from proplastids to chloroplasts.
Collapse
Affiliation(s)
- D Wang
- The Key Laboratory of Western Resources Biology and Biological Technology, College of Life Sciences, Northwest University, Xian, China; Shaanxi Province Key Laboratory of Biotechnology, College of Life Sciences, Northwest University, Xian, China
| | - A Fu
- The Key Laboratory of Western Resources Biology and Biological Technology, College of Life Sciences, Northwest University, Xian, China; Shaanxi Province Key Laboratory of Biotechnology, College of Life Sciences, Northwest University, Xian, China.
| |
Collapse
|
14
|
|
15
|
Pennisi R, Salvi D, Brandi V, Angelini R, Ascenzi P, Polticelli F. Molecular Evolution of Alternative Oxidase Proteins: A Phylogenetic and Structure Modeling Approach. J Mol Evol 2016; 82:207-18. [PMID: 27090422 DOI: 10.1007/s00239-016-9738-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 04/06/2016] [Indexed: 11/30/2022]
Abstract
Alternative oxidases (AOXs) are mitochondrial cyanide-resistant membrane-bound metallo-proteins catalyzing the oxidation of ubiquinol and the reduction of oxygen to water bypassing two sites of proton pumping, thus dissipating a major part of redox energy into heat. Here, the structure of Arabidopsis thaliana AOX 1A has been modeled using the crystal structure of Trypanosoma brucei AOX as a template. Analysis of this model and multiple sequence alignment of members of the AOX family from all kingdoms of Life indicate that AOXs display a high degree of conservation of the catalytic core, which is formed by a four-α-helix bundle, hosting the di-iron catalytic site, and is flanked by two additional α-helices anchoring the protein to the membrane. Plant AOXs display a peculiar covalent dimerization mode due to the conservation in the N-terminal region of a Cys residue forming the inter-monomer disulfide bond. The multiple sequence alignment has also been used to infer a phylogenetic tree of AOXs whose analysis shows a polyphyletic origin for the AOXs found in Fungi and a monophyletic origin of the AOXs of Eubacteria, Mycetozoa, Euglenozoa, Metazoa, and Land Plants. This suggests that AOXs evolved from a common ancestral protein in each of these kingdoms. Within the Plant AOX clade, the AOXs of monocotyledon plants form two distinct clades which have unresolved relationships relative to the monophyletic clade of the AOXs of dicotyledonous plants. This reflects the sequence divergence of the N-terminal region, probably due to a low selective pressure for sequence conservation linked to the covalent homo-dimerization mode.
Collapse
Affiliation(s)
- Rosa Pennisi
- Department of Sciences, Roma Tre University, Viale Guglielmo Marconi 446, 00146, Rome, Italy
| | - Daniele Salvi
- CIBIO-InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Campus Agrário de Vairão, 4485-661, Vairão, Portugal
| | - Valentina Brandi
- Department of Sciences, Roma Tre University, Viale Guglielmo Marconi 446, 00146, Rome, Italy
| | - Riccardo Angelini
- Department of Sciences, Roma Tre University, Viale Guglielmo Marconi 446, 00146, Rome, Italy
| | - Paolo Ascenzi
- Department of Sciences, Roma Tre University, Viale Guglielmo Marconi 446, 00146, Rome, Italy
| | - Fabio Polticelli
- Department of Sciences, Roma Tre University, Viale Guglielmo Marconi 446, 00146, Rome, Italy. .,National Institute of Nuclear Physics, Roma Tre Section, 00146, Rome, Italy.
| |
Collapse
|
16
|
Campos MD, Nogales A, Cardoso HG, Kumar SR, Nobre T, Sathishkumar R, Arnholdt-Schmitt B. Stress-Induced Accumulation of DcAOX1 and DcAOX2a Transcripts Coincides with Critical Time Point for Structural Biomass Prediction in Carrot Primary Cultures (Daucus carota L.). Front Genet 2016; 7:1. [PMID: 26858746 PMCID: PMC4731517 DOI: 10.3389/fgene.2016.00001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 01/07/2016] [Indexed: 11/18/2022] Open
Abstract
Stress-adaptive cell plasticity in target tissues and cells for plant biomass growth is important for yield stability. In vitro systems with reproducible cell plasticity can help to identify relevant metabolic and molecular events during early cell reprogramming. In carrot, regulation of the central root meristem is a critical target for yield-determining secondary growth. Calorespirometry, a tool previously identified as promising for predictive growth phenotyping has been applied to measure the respiration rate in carrot meristem. In a carrot primary culture system (PCS), this tool allowed identifying an early peak related with structural biomass formation during lag phase of growth, around the 4th day of culture. In the present study, we report a dynamic and correlated expression of carrot AOX genes (DcAOX1 and DcAOX2a) during PCS lag phase and during exponential growth. Both genes showed an increase in transcript levels until 36 h after explant inoculation, and a subsequent down-regulation, before the initiation of exponential growth. In PCS growing at two different temperatures (21°C and 28°C), DcAOX1 was also found to be more expressed in the highest temperature. DcAOX genes' were further explored in a plant pot experiment in response to chilling, which confirmed the early AOX transcript increase prior to the induction of a specific anti-freezing gene. Our findings point to DcAOX1 and DcAOX2a as being reasonable candidates for functional marker development related to early cell reprogramming. While the genomic sequence of DcAOX2a was previously described, we characterize here the complete genomic sequence of DcAOX1.
Collapse
Affiliation(s)
- M. Doroteia Campos
- EU Marie Curie Chair, ICAAM – Instituto de Ciências Agrárias e Ambientais Mediterrânicas, IIFA-Instituto de Formação e Investigação Avançada, Universidade de ÉvoraÉvora, Portugal
| | - Amaia Nogales
- EU Marie Curie Chair, ICAAM – Instituto de Ciências Agrárias e Ambientais Mediterrânicas, IIFA-Instituto de Formação e Investigação Avançada, Universidade de ÉvoraÉvora, Portugal
| | - Hélia G. Cardoso
- EU Marie Curie Chair, ICAAM – Instituto de Ciências Agrárias e Ambientais Mediterrânicas, IIFA-Instituto de Formação e Investigação Avançada, Universidade de ÉvoraÉvora, Portugal
| | - Sarma R. Kumar
- EU Marie Curie Chair, ICAAM – Instituto de Ciências Agrárias e Ambientais Mediterrânicas, IIFA-Instituto de Formação e Investigação Avançada, Universidade de ÉvoraÉvora, Portugal
- Molecular Plant Biology and Biotechnology Division, Council of Scientific and Industrial Research–Central Institute of Medicinal and Aromatic Plants Research CentreBangalore, India
| | - Tânia Nobre
- EU Marie Curie Chair, ICAAM – Instituto de Ciências Agrárias e Ambientais Mediterrânicas, IIFA-Instituto de Formação e Investigação Avançada, Universidade de ÉvoraÉvora, Portugal
| | - Ramalingam Sathishkumar
- Plant Genetic Engineering Laboratory, Department of Biotechnology, Bharathiar UniversityCoimbatore, India
| | - Birgit Arnholdt-Schmitt
- EU Marie Curie Chair, ICAAM – Instituto de Ciências Agrárias e Ambientais Mediterrânicas, IIFA-Instituto de Formação e Investigação Avançada, Universidade de ÉvoraÉvora, Portugal
| |
Collapse
|
17
|
Rogov AG, Sukhanova EI, Uralskaya LA, Aliverdieva DA, Zvyagilskaya RA. Alternative oxidase: distribution, induction, properties, structure, regulation, and functions. BIOCHEMISTRY (MOSCOW) 2015; 79:1615-34. [PMID: 25749168 DOI: 10.1134/s0006297914130112] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The respiratory chain in the majority of organisms with aerobic type metabolism features the concomitant existence of the phosphorylating cytochrome pathway and the cyanide- and antimycin A-insensitive oxidative route comprising a so-called alternative oxidase (AOX) as a terminal oxidase. In this review, the history of AOX discovery is described. Considerable evidence is presented that AOX occurs widely in organisms at various levels of organization and is not confined to the plant kingdom. This enzyme has not been found only in Archaea, mammals, some yeasts and protists. Bioinformatics research revealed the sequences characteristic of AOX in representatives of various taxonomic groups. Based on multiple alignments of these sequences, a phylogenetic tree was constructed to infer their possible evolution. The ways of AOX activation, as well as regulatory interactions between AOX and the main respiratory chain are described. Data are summarized concerning the properties of AOX and the AOX-encoding genes whose expression is either constitutive or induced by various factors. Information is presented on the structure of AOX, its active center, and the ubiquinone-binding site. The principal functions of AOX are analyzed, including the cases of cell survival, optimization of respiratory metabolism, protection against excess of reactive oxygen species, and adaptation to variable nutrition sources and to biotic and abiotic stress factors. It is emphasized that different AOX functions complement each other in many instances and are not mutually exclusive. Examples are given to demonstrate that AOX is an important tool to overcome the adverse aftereffects of restricted activity of the main respiratory chain in cells and whole animals. This is the first comprehensive review on alternative oxidases of various organisms ranging from yeasts and protists to vascular plants.
Collapse
Affiliation(s)
- A G Rogov
- Bach Institute of Biochemistry, Russian Academy of Sciences, Moscow, 119071, Russia.
| | | | | | | | | |
Collapse
|
18
|
Pu X, Lv X, Tan T, Fu F, Qin G, Lin H. Roles of mitochondrial energy dissipation systems in plant development and acclimation to stress. ANNALS OF BOTANY 2015; 116:583-600. [PMID: 25987710 PMCID: PMC4577992 DOI: 10.1093/aob/mcv063] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 02/16/2015] [Accepted: 03/27/2015] [Indexed: 05/18/2023]
Abstract
BACKGROUND Plants are sessile organisms that have the ability to integrate external cues into metabolic and developmental signals. The cues initiate specific signal cascades that can enhance the tolerance of plants to stress, and these mechanisms are crucial to the survival and fitness of plants. The adaption of plants to stresses is a complex process that involves decoding stress inputs as energy-deficiency signals. The process functions through vast metabolic and/or transcriptional reprogramming to re-establish the cellular energy balance. Members of the mitochondrial energy dissipation pathway (MEDP), alternative oxidases (AOXs) and uncoupling proteins (UCPs), act as energy mediators and might play crucial roles in the adaption of plants to stresses. However, their roles in plant growth and development have been relatively less explored. SCOPE This review summarizes current knowledge about the role of members of the MEDP in plant development as well as recent advances in identifying molecular components that regulate the expression of AOXs and UCPs. Highlighted in particular is a comparative analysis of the expression, regulation and stress responses between AOXs and UCPs when plants are exposed to stresses, and a possible signal cross-talk that orchestrates the MEDP, reactive oxygen species (ROS), calcium signalling and hormone signalling. CONCLUSIONS The MEDP might act as a cellular energy/metabolic mediator that integrates ROS signalling, energy signalling and hormone signalling with plant development and stress accumulation. However, the regulation of MEDP members is complex and occurs at transcriptional, translational, post-translational and metabolic levels. How this regulation is linked to actual fluxes through the AOX/UCP in vivo remains elusive.
Collapse
Affiliation(s)
- Xiaojun Pu
- Ministry of Education Key Laboratory for Bio-Resource & Eco-Environment and Plant Physiology Laboratory, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610064, China
| | - Xin Lv
- Ministry of Education Key Laboratory for Bio-Resource & Eco-Environment and Plant Physiology Laboratory, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610064, China
| | - Tinghong Tan
- Ministry of Education Key Laboratory for Bio-Resource & Eco-Environment and Plant Physiology Laboratory, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610064, China
| | - Faqiong Fu
- Ministry of Education Key Laboratory for Bio-Resource & Eco-Environment and Plant Physiology Laboratory, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610064, China
| | - Gongwei Qin
- Ministry of Education Key Laboratory for Bio-Resource & Eco-Environment and Plant Physiology Laboratory, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610064, China
| | - Honghui Lin
- Ministry of Education Key Laboratory for Bio-Resource & Eco-Environment and Plant Physiology Laboratory, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610064, China
| |
Collapse
|
19
|
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
|
20
|
Erdal S, Genisel M, Turk H, Dumlupinar R, Demir Y. Modulation of alternative oxidase to enhance tolerance against cold stress of chickpea by chemical treatments. JOURNAL OF PLANT PHYSIOLOGY 2015; 175:95-101. [PMID: 25543861 DOI: 10.1016/j.jplph.2014.10.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 09/17/2014] [Accepted: 10/10/2014] [Indexed: 05/04/2023]
Abstract
The alternative oxidase (AOX) is the enzyme responsible for the alternative respiratory pathway. This experiment was conducted to examine the influence on cold tolerance ability of chickpea (Cicer aurentium cv. Müfitbey) seedlings of AOX activator (pyruvate), AOX inhibitor (salicylhydroxamic acid (SHAM)) and an inhibitor of the cytochrome pathway of respiration (antimycin A) treatments. 5mM pyruvate, 2μM antimycin A and 4mM SHAM solutions were exogenously applied to thirteen-day-old chickpea leaves and then the seedlings were transferred to a different plant growth chamber arranged to 10/5°C (day/night) for 48h. Cold stress markedly increased the activities of antioxidant enzymes compared to controls. Pyruvate and antimycin A significantly increased the cold-induced increase in antioxidant activity but SHAM decreased it. Cold-induced increases in superoxide anion, hydrogen peroxide, and lipid peroxidation levels were significantly reduced by pyruvate and antimycin A, but increased by SHAM treatment. Pyruvate and antimycin A application increased both the activity and protein expression of AOX in comparison to cold stress alone. However, SHAM significantly decreased activity of AOX but did not affect its expression. Total cellular respiration values (TCRV) supported the changes in activity and expression of AOX. While TCRV were increased by cold and pyruvate, they were significantly reduced by SHAM and especially antimycin A. These results indicate that pyruvate and antimycin A applications were effective in reducing oxidative stress by activating the alternative respiratory pathway as well as antioxidant activity. Furthermore, direct activation of AOX, rather than inhibition of the cytochrome pathway, was the most effective way to mitigate cold stress.
Collapse
Affiliation(s)
- Serkan Erdal
- Department of Biology, Science Faculty, Ataturk University, Erzurum, Turkey.
| | - Mucip Genisel
- Organic Agriculture Program, Vocational High School, Agri Ibrahim Cecen University, 04100 Agri, Turkey
| | - Hulya Turk
- Department of Biology, Science Faculty, Ataturk University, Erzurum, Turkey
| | - Rahmi Dumlupinar
- Department of Biology, Science Faculty, Ataturk University, Erzurum, Turkey
| | - Yavuz Demir
- Department of Biology, K. K. Education Faculty, Ataturk University, Erzurum, Turkey
| |
Collapse
|
21
|
Antos-Krzeminska N, Jarmuszkiewicz W. Functional expression of the Acanthamoeba castellanii alternative oxidase in Escherichia coli; regulation of the activity and evidence for Acaox gene function. Biochem Cell Biol 2014; 92:235-41. [PMID: 24860925 DOI: 10.1139/bcb-2014-0014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To evidence Acanthamoeba castellanii alternative oxidase (AcAOX) gene product function, we studied alterations in the levels of mRNA and protein and AcAOX activity during growth in amoeba batch culture. Moreover, heterologous expression of AcAOX in AOX-deficient Escherichia coli confirmed by the protein immunodetection and functional studies was performed. Despite the presence of native bo and bd quinol oxidases in E. coli membrane, from which the latter is known to be cyanide-resistant, functional expression of AcAOX in E. coli conferred cyanide-resistant benzohydroxamate-sensitive respiration on the bacteria. Moreover, AcAOX activity in transformed bacteria was stimulated by GMP and inhibited by ATP, indicating that AcAOX is regulated by mutual exclusion of purine nucleotides, which was previously demonstrated in the mitochondria of A. castellanii.
Collapse
Affiliation(s)
- Nina Antos-Krzeminska
- Department of Bioenergetics, Adam Mickiewicz University, Umultowska 89, 61-614 Poznan, Poland
| | | |
Collapse
|
22
|
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
|
23
|
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]
|
24
|
Moore AL, Shiba T, Young L, Harada S, Kita K, Ito K. Unraveling the heater: new insights into the structure of the alternative oxidase. ANNUAL REVIEW OF PLANT BIOLOGY 2013; 64:637-63. [PMID: 23638828 DOI: 10.1146/annurev-arplant-042811-105432] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The alternative oxidase is a membrane-bound ubiquinol oxidase found in the majority of plants as well as many fungi and protists, including pathogenic organisms such as Trypanosoma brucei. It catalyzes a cyanide- and antimycin-A-resistant oxidation of ubiquinol and the reduction of oxygen to water, short-circuiting the mitochondrial electron-transport chain prior to proton translocation by complexes III and IV, thereby dramatically reducing ATP formation. In plants, it plays a key role in cellular metabolism, thermogenesis, and energy homeostasis and is generally considered to be a major stress-induced protein. We describe recent advances in our understanding of this protein's structure following the recent successful crystallization of the alternative oxidase from T. brucei. We focus on the nature of the active site and ubiquinol-binding channels and propose a mechanism for the reduction of oxygen to water based on these structural insights. We also consider the regulation of activity at the posttranslational and retrograde levels and highlight challenges for future research.
Collapse
Affiliation(s)
- Anthony L Moore
- Biochemistry and Molecular Biology, School of Life Sciences, University of Sussex, Brighton BN1 9QG, United Kingdom.
| | | | | | | | | | | |
Collapse
|
25
|
cDNA cloning and expression analysis of a putative alternative oxidase HsAOX1 from wild barley (Hordeum spontaneum). Genes Genomics 2012. [DOI: 10.1007/s13258-011-0164-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
26
|
Martins VDP, Dinamarco TM, Curti C, Uyemura SA. Classical and alternative components of the mitochondrial respiratory chain in pathogenic fungi as potential therapeutic targets. J Bioenerg Biomembr 2011; 43:81-8. [PMID: 21271279 DOI: 10.1007/s10863-011-9331-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The frequency of opportunistic fungal infection has increased drastically, mainly in patients who are immunocompromised due to organ transplant, leukemia or HIV infection. In spite of this, only a few classes of drugs with a limited array of targets, are available for antifungal therapy. Therefore, more specific and less toxic drugs with new molecular targets is desirable for the treatment of fungal infections. In this context, searching for differences between mitochondrial mammalian hosts and fungi in the classical and alternative components of the mitochondrial respiratory chain may provide new potential therapeutic targets for this purpose.
Collapse
Affiliation(s)
- Vicente de Paulo Martins
- Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | | | | | | |
Collapse
|
27
|
Kido Y, Sakamoto K, Nakamura K, Harada M, Suzuki T, Yabu Y, Saimoto H, Yamakura F, Ohmori D, Moore A, Harada S, Kita K. Purification and kinetic characterization of recombinant alternative oxidase from Trypanosoma brucei brucei. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:443-50. [DOI: 10.1016/j.bbabio.2009.12.021] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Revised: 12/23/2009] [Accepted: 12/25/2009] [Indexed: 10/20/2022]
|
28
|
Albury MS, Elliott C, Moore AL. Towards a structural elucidation of the alternative oxidase in plants. PHYSIOLOGIA PLANTARUM 2009; 137:316-27. [PMID: 19719482 DOI: 10.1111/j.1399-3054.2009.01270.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
In addition to the conventional cytochrome c oxidase, mitochondria of all plants studied to date contain a second cyanide-resistant terminal oxidase or alternative oxidase (AOX). The AOX is located in the inner mitochondrial membrane and branches from the cytochrome pathway at the level of the quinone pool. It is non-protonmotive and couples the oxidation of ubiquinone to the reduction of oxygen to water. For many years, the AOX was considered to be confined to plants, fungi and a small number of protists. Recently, it has become apparent that the AOX occurs in wide range of organisms including prokaryotes and a moderate number of animal species. In this paper, we provide an overview of general features and current knowledge available about the AOX with emphasis on structure, the active site and quinone-binding site. Characterisation of the AOX has advanced considerably over recent years with information emerging about the role of the protein, regulatory regions and functional sites. The large number of sequences available is now enabling us to obtain a clearer picture of evolutionary origins and diversity.
Collapse
Affiliation(s)
- Mary S Albury
- Division of Biochemistry and Biomedical Sciences, School of Life Sciences, University of Sussex, Falmer, Brighton BN19QG, UK
| | | | | |
Collapse
|
29
|
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
|
30
|
Santos Macedo E, Cardoso HG, Hernández A, Peixe AA, Polidoros A, Ferreira A, Cordeiro A, Arnholdt-Schmitt B. Physiologic responses and gene diversity indicate olive alternative oxidase as a potential source for markers involved in efficient adventitious root induction. PHYSIOLOGIA PLANTARUM 2009; 137:532-52. [PMID: 19941624 DOI: 10.1111/j.1399-3054.2009.01302.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Olive (Olea europaea L.) trees are mainly propagated by adventitious rooting of semi-hardwood cuttings. However, efficient commercial propagation of valuable olive tree cultivars or landraces by semi-hardwood cuttings can often be restricted by a low rooting capacity. We hypothesize that root induction is a plant cell reaction linked to oxidative stress and that activity of stress-induced alternative oxidase (AOX) is importantly involved in adventitious rooting. To identify AOX as a source for potential functional marker sequences that may assist tree breeding, genetic variability has to be demonstrated that can affect gene regulation. The paper presents an applied, multidisciplinary research approach demonstrating first indications of an important relationship between AOX activity and differential adventitious rooting in semi-hardwood cuttings. Root induction in the easy-to-root Portuguese cultivar 'Cobrançosa' could be significantly reduced by treatment with salicyl-hydroxamic acid, an inhibitor of AOX activity. On the contrary, treatment with H2O2 or pyruvate, both known to induce AOX activity, increased the degree of rooting. Recently, identification of several O. europaea (Oe) AOX gene sequences has been reported from our group. Here we present for the first time partial sequences of OeAOX2. To search for polymorphisms inside of OeAOX genes, partial OeAOX2 sequences from the cultivars 'Galega vulgar', 'Cobrançosa' and 'Picual' were cloned from genomic DNA and cDNA, including exon, intron and 3'-untranslated regions (3'-UTRs) sequences. The data revealed polymorphic sites in several regions of OeAOX2. The 3'-UTR was the most important source for polymorphisms showing 5.7% of variability. Variability in the exon region accounted 3.4 and 2% in the intron. Further, analysis performed at the cDNA from microshoots of 'Galega vulgar' revealed transcript length variation for the 3'-UTR of OeAOX2 ranging between 76 and 301 bp. The identified polymorphisms and 3'-UTR length variation can be explored in future studies for effects on gene regulation and a potential linkage to olive rooting phenotypes in view of marker-assisted plant selection.
Collapse
|
31
|
Henriquez FL, McBride J, Campbell SJ, Ramos T, Ingram PR, Roberts F, Tinney S, Roberts CW. Acanthamoeba alternative oxidase genes: Identification, characterisation and potential as antimicrobial targets. Int J Parasitol 2009; 39:1417-24. [DOI: 10.1016/j.ijpara.2009.04.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2009] [Revised: 04/15/2009] [Accepted: 04/28/2009] [Indexed: 11/24/2022]
|
32
|
Fu A, Aluru M, Rodermel SR. Conserved active site sequences in Arabidopsis plastid terminal oxidase (PTOX): in vitro and in planta mutagenesis studies. J Biol Chem 2009; 284:22625-32. [PMID: 19542226 PMCID: PMC2755669 DOI: 10.1074/jbc.m109.017905] [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] [Received: 05/06/2009] [Revised: 06/16/2009] [Indexed: 11/06/2022] Open
Abstract
The plastid terminal oxidase (PTOX) is distantly related to the mitochondrial alternative oxidase (AOX). Both are members of the diiron carboxylate quinol oxidase (DOX) class of proteins. PTOX and AOX contain 20 highly conserved amino acids, six of which are Fe-binding ligands. We have previously used in vitro and in planta activity assays to examine the functional importance of the Fe-binding sites. In this report, we conduct alanine-scanning mutagenesis on the 14 other conserved sites using our in vitro and in planta assay procedures. We found that the 14 sites fall into three classes: (i) Ala-139, Pro-142, Glu-171, Asn-174, Leu-179, Pro-216, Ala-230, Asp-287, and Arg-293 are dispensable for activity; (ii) Tyr-234 and Asp-295 are essential for activity; and (iii) Leu-135, His-151, and Tyr-212 are important but not essential for activity. Our data are consistent with the proposed role of some of these residues in active site conformation, substrate binding, and/or catalysis. Titration experiments showed that down-regulation of PTOX to approximately 3% of wild-type levels did not compromise plant growth, at least under ambient growth conditions. This suggests that PTOX is normally in excess, especially early in thylakoid membrane biogenesis.
Collapse
Affiliation(s)
- Aigen Fu
- From the Department of Genetics, Development and Cell Biology, Iowa State University, Ames, Iowa 50011
| | - Maneesha Aluru
- From the Department of Genetics, Development and Cell Biology, Iowa State University, Ames, Iowa 50011
| | - Steven R. Rodermel
- From the Department of Genetics, Development and Cell Biology, Iowa State University, Ames, Iowa 50011
| |
Collapse
|
33
|
Vigani G, Maffi D, Zocchi G. Iron availability affects the function of mitochondria in cucumber roots. THE NEW PHYTOLOGIST 2009; 182:127-136. [PMID: 19192186 DOI: 10.1111/j.1469-8137.2008.02747.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
* In Strategy-I-plants, iron (Fe) deficiency induces processes leading to increased Fe solubilization in the rhizosphere, including reduction by ferric reductases and active proton extrusion. These processes require active respiration to function. In this work we investigated the effect of Fe deficiency on respiratory activities of cucumber (Cucumis sativus) roots. * We compared oxygen consumption rate and the activities of the respiratory chain complexes on purified mitochondria from roots grown in the presence or absence of Fe using biochemical and molecular approaches. * Oxygen consumption rate in apex roots was increased under Fe deficiency that was mostly resistant to KCN and salycilichydroxamic acid (SHAM) inhibitors, indicating other oxygen-consuming reactions could be present. Indeed, enzyme assays revealed that lack of Fe induced a decrease in the activities of respiratory complexes that was proportional to the number of Fe atoms in each complex. A decrease of cyt c, Rieske and NAD9 proteins was also observed. Transmission electron microscopy (TEM) analysis showed that mitochondria undergo structural changes under Fe deficiency. * Our data show that mitochondria and the electron transport chain are an important target of Fe limitation and that mitochondria modify their function to meet higher demands for organic acids while restricting the activity of enzymes with Fe cofactors.
Collapse
Affiliation(s)
- Gianpiero Vigani
- Dipartimento di Produzione Vegetale, Università degli Studi di Milano, via Celoria 2, 20133 Milano, Italy
| | - Dario Maffi
- Istituto di Patologia Vegetale, Università degli Studi di Milano, via Celoria 2, 20133 Milano, Italy
| | - Graziano Zocchi
- Dipartimento di Produzione Vegetale, Università degli Studi di Milano, via Celoria 2, 20133 Milano, Italy
| |
Collapse
|
34
|
Further insights into the structure of the alternative oxidase: from plants to parasites. Biochem Soc Trans 2008; 36:1022-6. [PMID: 18793182 DOI: 10.1042/bst0361022] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The AOX (alternative oxidase) is a non-protonmotive ubiquinol-oxygen oxidoreductase that couples the oxidation of ubiquinol with the complete reduction of water. Although it has long been recognized that it is ubiquitous among the plant kingdom, it has only recently become apparent that it is also widely found in other organisms including some human parasites. In this paper, we review experimental studies that have contributed to our current understanding of its structure, with particular reference to the catalytic site. Furthermore, we propose a model for the ubiquinol-binding site which identifies a hydrophobic pocket, between helices II and III, leading from a proposed membrane-binding domain to the catalytic domain.
Collapse
|
35
|
Hildebrandt TM, Grieshaber MK. Redox regulation of mitochondrial sulfide oxidation in the lugworm, Arenicola marina. ACTA ACUST UNITED AC 2008; 211:2617-23. [PMID: 18689415 DOI: 10.1242/jeb.019729] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Sulfide oxidation in the lugworm, Arenicola marina (L.), is most likely localized in the mitochondria, which can either produce ATP with sulfide as a substrate or detoxify it via an alternative oxidase. The present study identified selective activators of the energy-conserving and the detoxifying sulfide oxidation pathways respectively. In the presence of the ROS scavengers glutathione (GSH) and ascorbate, isolated lugworm mitochondria rapidly oxidized up to 100 micromoll(-1) sulfide with maximal oxygen consumption rates but did not produce any ATP in the process. Under these conditions, salicylhydroxamic acid (SHAM), which is an inhibitor of the alternative oxidase of plant mitochondria, completely blocked oxygen consumption whereas inhibitors of complex III and IV had hardly any effect. By contrast, dehydroascorbate (DHA) enabled the mitochondria to gain ATP from sulfide oxidation even if the sulfide concentration far exceeded the threshold for inhibition of cytochrome oxidase. In the presence of dehydroascorbate, respiratory rates were independent of sulfide concentrations, with a respiratory control ratio of 2.1+/-0.2, and both oxygen consumption and ATP production were completely inhibited by myxothiazol and sodium azide but only marginally by SHAM. The present data indicate that a redox mechanism may contribute to the regulation of sulfide oxidation in lugworm mitochondria in vivo. Thus, mitochondria are presumably much more sulfide resistant in a cellular context than previously thought.
Collapse
|
36
|
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
|
37
|
Uribe D, Khachatourians GG. Identification and characterization of an alternative oxidase in the entomopathogenic fungusMetarhizium anisopliae. Can J Microbiol 2008; 54:119-27. [DOI: 10.1139/w07-127] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mitochondria of Metarhizium anisopliae contain an alternative oxidase (AOX), which reduces oxygen to water by accepting electrons directly from ubiquinol. AOX activity is demonstrated in situ as a constitutive enzyme. Greatest activity of AOX appears at the beginning and at the end of the fungal developmental cycle, germination of aerial conidia and the formation of submerged conidia, respectively. Changes in nutritional conditions, e.g., the presence of host insect cuticle or nutrient starvation had no effect on the induction of AOX activity. Antimycin A, an electron transport chain inhibitor, induced AOX activity. Cloning of the AOX DNA and the alignment of the deduced amino acid sequence of a segment of the AOX gene from M. anisopliae shows structural similarities with other AOX sequences with differing levels of variation when compared with homologous sequences from plants, yeasts, and filamentous fungi. Alternative oxidase in entomopathogenic fungi may have a positive contribution to ecological fitness.
Collapse
Affiliation(s)
- Daniel Uribe
- BioInsecticide Research Laboratory, Department of Applied Microbiology and Food Science, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK S7N 5A8, Canada
- Universidad Nacional de Colombia, Instituto de Biotecnologia, A.A. 14-490, Santafe de Bogota D.C., Colombia
| | - George G. Khachatourians
- BioInsecticide Research Laboratory, Department of Applied Microbiology and Food Science, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK S7N 5A8, Canada
- Universidad Nacional de Colombia, Instituto de Biotecnologia, A.A. 14-490, Santafe de Bogota D.C., Colombia
| |
Collapse
|
38
|
Onda Y, Kato Y, Abe Y, Ito T, Ito-Inaba Y, Morohashi M, Ito Y, Ichikawa M, Matsukawa K, Otsuka M, Koiwa H, Ito K. Pyruvate-sensitive AOX exists as a non-covalently associated dimer in the homeothermic spadix of the skunk cabbage, Symplocarpus renifolius. FEBS Lett 2007; 581:5852-8. [PMID: 18060878 DOI: 10.1016/j.febslet.2007.11.061] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2007] [Revised: 11/20/2007] [Accepted: 11/20/2007] [Indexed: 11/25/2022]
Abstract
The cyanide-resistant alternative oxidase (AOX) is a homodimeric protein whose activity can be regulated by the oxidation/reduction state and by alpha-keto acids. To further clarify the role of AOX in the skunk cabbage, Symplocarpus renifolius, we have performed expression and functional analyses of the encoding gene. Among the various tissues in the skunk cabbage, SrAOX transcripts were found to be specifically expressed in the thermogenic spadix. Moreover, our data demonstrate that the SrAOX protein exists as a non-covalently associated dimer in the thermogenic spadix, and is more sensitive to pyruvate than to other carboxylic acids. Our results suggest that the pyruvate-mediated modification of SrAOX activity plays a significant role in thermoregulation in the skunk cabbage.
Collapse
Affiliation(s)
- Yoshihiko Onda
- United Graduate School of Agricultural Science, Iwate University, Ueda, Morioka, Iwate 020 8550, Japan
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
39
|
Kern A, Hartner FS, Freigassner M, Spielhofer J, Rumpf C, Leitner L, Fröhlich KU, Glieder A. Pichia pastoris "just in time" alternative respiration. MICROBIOLOGY-SGM 2007; 153:1250-1260. [PMID: 17379734 DOI: 10.1099/mic.0.2006/001404-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Alternative oxidases (Aox or Aod) are present in the mitochondria of plants, fungi and many types of yeast. These enzymes transfer electrons from the ubiquinol pool directly to oxygen without contributing to the proton transfer across the mitochondrial membrane. Alternative oxidases are involved in stress responses, programmed cell death and maintenance of the cellular redox balance. The alternative oxidase gene of the methylotrophic yeast Pichia pastoris was isolated and cloned to study its regulation and the effects of deregulation of the alternative respiration by overexpression or disruption of the gene. Both disruption and overexpression had negative effects on the biomass yield; however, the growth rate and substrate uptake rate of the strain overexpressing the alternative oxidase were slightly increased. These effects were even more pronounced when higher glucose concentrations were used. The occurrence of free intracellular radicals and cell death phenomena was investigated using dihydrorhodamine 123 and the TUNEL test. The results suggest a major contribution of the alternative oxidase to P. pastoris cell viability. The negative effects of deregulated alternative respiration clearly indicated the importance of precise regulation of the alternative oxidase in this yeast.
Collapse
Affiliation(s)
- Alexander Kern
- Institute for Molecular Biotechnology, Graz University of Technology, Petersgasse 14/2, A-8010 Graz, Austria
| | - Franz S Hartner
- Institute for Molecular Biotechnology, Graz University of Technology, Petersgasse 14/2, A-8010 Graz, Austria
| | - Maria Freigassner
- Institute for Molecular Biotechnology, Graz University of Technology, Petersgasse 14/2, A-8010 Graz, Austria
| | - Julia Spielhofer
- Institute for Molecular Biosciences, Karl-Franzens University, Universitaetsplatz 2, A-8010 Graz, Austria
| | - Cornelia Rumpf
- Institute for Molecular Biosciences, Karl-Franzens University, Universitaetsplatz 2, A-8010 Graz, Austria
| | - Laura Leitner
- Institute for Molecular Biosciences, Karl-Franzens University, Universitaetsplatz 2, A-8010 Graz, Austria
| | - Kai-Uwe Fröhlich
- Institute for Molecular Biosciences, Karl-Franzens University, Universitaetsplatz 2, A-8010 Graz, Austria
| | - Anton Glieder
- Institute for Molecular Biotechnology, Graz University of Technology, Petersgasse 14/2, A-8010 Graz, Austria
| |
Collapse
|
40
|
Magnani T, Soriani FM, Martins VP, Nascimento AM, Tudella VG, Curti C, Uyemura SA. Cloning and functional expression of the mitochondrial alternative oxidase ofAspergillus fumigatusand its induction by oxidative stress. FEMS Microbiol Lett 2007; 271:230-8. [PMID: 17425662 DOI: 10.1111/j.1574-6968.2007.00716.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Aspergillus fumigatus possesses a branched mitochondrial electron transport chain, with both cyanide-sensitive and -insensitive oxygen-consumption activities. Mitochondrial reactive oxygen species mediate signaling for alternative oxidase (AOX) expression. A 1173 bp-long Afaox gene encoding a 40 kDa protein has been cloned and identified. Recombinant constructs containing the Afaox ORF were transformed into Escherichia coli and Saccharomyces cerevisiae for heterologous expression. In A. fumigatus, AOX activity and mRNA expression were both induced with menadione or paraquat, suggesting an important role of AOX under oxidative stress. Therefore, positive transformants showed a cyanide-resistant and salicylhydroxamic acid-sensitive respiration, whereas in control cells the oxygen uptake was completely inhibited after KCN addition.
Collapse
Affiliation(s)
- T Magnani
- Dep Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, SP, Brazil
| | | | | | | | | | | | | |
Collapse
|
41
|
Chaudhuri M, Ott RD, Hill GC. Trypanosome alternative oxidase: from molecule to function. Trends Parasitol 2006; 22:484-91. [PMID: 16920028 DOI: 10.1016/j.pt.2006.08.007] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2006] [Revised: 07/06/2006] [Accepted: 08/04/2006] [Indexed: 10/24/2022]
Abstract
Trypanosome alternative oxidase (TAO) is the cytochrome-independent terminal oxidase of the mitochondrial electron transport chain. TAO is a diiron protein that transfers electrons from ubiquinol to oxygen, reducing the oxygen to water. The mammalian bloodstream forms of Trypanosoma brucei depend solely on TAO for respiration. The inhibition of TAO by salicylhydroxamic acid (SHAM) or ascofuranone is trypanocidal. TAO is present at a reduced level in the procyclic form of T. brucei, where it is engaged in respiration and is also needed for developmental processes. Alternative oxidases similar to TAO have been found in a wide variety of organisms but not in mammals, thus rendering TAO an important chemotherapeutic target for African trypanosomiasis.
Collapse
Affiliation(s)
- Minu Chaudhuri
- Division of Microbial Pathogenesis and Immune Response, Department of Biomedical Sciences, Meharry Medical College, Nashville, TN 37208, USA.
| | | | | |
Collapse
|
42
|
Suzuki T, Hashimoto T, Yabu Y, Majiwa PAO, Ohshima S, Suzuki M, Lu S, Hato M, Kido Y, Sakamoto K, Nakamura K, Kita K, Ohta N. Alternative oxidase (AOX) genes of African trypanosomes: phylogeny and evolution of AOX and plastid terminal oxidase families. J Eukaryot Microbiol 2005; 52:374-81. [PMID: 16014016 DOI: 10.1111/j.1550-7408.2005.00050.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To clarify evolution and phylogenetic relationships of trypanosome alternative oxidase (AOX) molecules, AOX genes (cDNAs) of the African trypanosomes, Trypanosoma congolense and Trypanosoma evansi, were cloned by PCR. Both AOXs possess conserved consensus motifs (-E-, -EXXH-). The putative amino acid sequence of the AOX of T. evansi was exactly the same as that of T. brucei. A protein phylogeny of trypanosome AOXs revealed that three genetically and pathogenically distinct strains of T. congolense are closely related to each other. When all known AOX sequences collected from current databases were analyzed, the common ancestor of these three Trypanosoma species shared a sister-group position to T. brucei/T. evansi. Monophyly of Trypanosoma spp. was clearly supported (100% bootstrap value) with Trypanosoma vivax placed at the most basal position of the Trypanosoma clade. Monophyly of other eukaryotic lineages, terrestrial plants + red algae, Metazoa, diatoms, Alveolata, oomycetes, green algae, and Fungi, was reconstructed in the best AOX tree obtained from maximum likelihood analysis, although some of these clades were not strongly supported. The terrestrial plants + red algae clade showed the closest affinity with an alpha-proteobacterium, Novosphingobium aromaticivorans, and the common ancestor of these lineages, was separated from other eukaryotes. Although the root of the AOX subtree was not clearly determined, subsequent phylogenetic analysis of the composite tree for AOX and plastid terminal oxidase (PTOX) demonstrated that PTOX and related cyanobacterial sequences are of a monophyletic origin and their common ancestor is linked to AOX sequences.
Collapse
Affiliation(s)
- Takashi Suzuki
- Department of Molecular Parasitology, Nagoya City University, Graduate School of Medical Sciences, Kawasumi, Mizuho 467-8601 Nagoya, Japan.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
43
|
Fu A, Park S, Rodermel S. Sequences required for the activity of PTOX (IMMUTANS), a plastid terminal oxidase: in vitro and in planta mutagenesis of iron-binding sites and a conserved sequence that corresponds to Exon 8. J Biol Chem 2005; 280:42489-96. [PMID: 16249174 DOI: 10.1074/jbc.m508940200] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The thylakoid membranes of most photosynthetic organisms contain a terminal oxidase (PTOX, the product of the Arabidopsis IMMUTANS gene) that functions in the oxidation of the plastoquinone pool. PTOX and AOX are diiron carboxylate proteins, and based on crystal structures of other members of this protein class, a structural model of PTOX has been proposed in which the ligation sphere of the diiron center is composed of six conserved histidine and glutamate residues. We tested the functional significance of these residues by site-directed mutagenesis of PTOX in vitro and in planta, taking advantage null immutans alleles for the latter studies. These experiments showed that the six iron-binding sites do not tolerate change, even conservative ones. We also examined the significance of a conserved sequence in (or near) the PTOX active site that corresponds precisely to Exon 8 of the IM gene. In vitro and in planta mutagenesis revealed that conserved amino acids within this domain can be altered but that deletion of all or part of the domain abolishes activity. Because protein accumulates normally in the deletion mutants, the data suggest that the conformation of the Exon 8 sequence is important for PTOX activity. An allele of immutans (designated 3639) was identified that lacks the Exon 8 sequence; it does not accumulate PTOX protein. Chloroplast import assays revealed that mutant enzymes lacking Exon 8 have enhanced turnover. We conclude that the Exon 8 domain is required not only for PTOX activity but also for its stability.
Collapse
Affiliation(s)
- Aigen Fu
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, Iowa 50011, USA
| | | | | |
Collapse
|
44
|
Affourtit C, Moore AL. Purification of the plant alternative oxidase from Arum maculatum: measurement, stability and metal requirement. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2004; 1608:181-9. [PMID: 14871496 DOI: 10.1016/j.bbabio.2003.12.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2003] [Revised: 12/03/2003] [Accepted: 12/10/2003] [Indexed: 10/26/2022]
Abstract
We have purified plant alternative oxidase (AOX) protein from the spadices of thermogenic Arum maculatum (cuckoo pint) to virtual homogeneity. The obtained enzyme fraction exhibits a high specific activity, consuming on average 32 micromol oxygen min(-1) mg(-1), which is completely stable for at least 6 months when the sample is stored at -70 degrees C. This exceptionally stable AOX activity is inhibited approximately 90% (I(50) approximately 10 microM) by 8-hydroxyquinoline (8-OHQ) and also, although to a lesser extent, by other metal chelators such as o-phenanthroline, alpha,alpha'-dipyridyl and EDTA. When inhibited by 8-OHQ, AOX activity is fully restored upon addition of 1.2 mM ferric iron, but neither ferrous iron nor manganese has any effect, whilst zinc decreases activity even further. Furthermore, we have developed a spectrophotometric assay to measure AOX activity in an accurate manner, which will facilitate future steady state and transient kinetic studies. The reliability of this assay is evidenced by retained stability of AOX protein during the course of the reaction, reproducibility of the measured initial rates, an observed 2:1 duroquinol-oxygen stoichiometry and by the fact that, in absolute terms, the measured rates of duroquinone formation and duroquinol disappearance are identical.
Collapse
Affiliation(s)
- Charles Affourtit
- Department of Biochemistry, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, United Kingdom.
| | | |
Collapse
|
45
|
Suzuki T, Hashimoto T, Yabu Y, Kido Y, Sakamoto K, Nihei CI, Hato M, Suzuki SI, Amano Y, Nagai K, Hosokawa T, Minagawa N, Ohta N, Kita K. Direct evidence for cyanide-insensitive quinol oxidase (alternative oxidase) in apicomplexan parasite Cryptosporidium parvum: phylogenetic and therapeutic implications. Biochem Biophys Res Commun 2004; 313:1044-52. [PMID: 14706648 DOI: 10.1016/j.bbrc.2003.12.038] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Cryptosporidium parvum is a parasitic protozoan that causes the diarrheal disease cryptosporidiosis, for which no satisfactory chemotherapy is currently available. Although the presence of mitochondria in this parasite has been suggested, its respiratory system is poorly understood due to difficulties in performing biochemical analyses. In order to better understand the respiratory chain of C. parvum, we surveyed its genomic DNA database in GenBank and identified a partial sequence encoding cyanide-insensitive alternative oxidase (AOX). Based on this sequence, we cloned C. parvum AOX (CpAOX) cDNA from the phylum apicomplexa for the first time. The deduced amino acid sequence (335 a.a.) of CpAOX contains diiron coordination motifs (-E-, -EXXH-) that are conserved among AOXs. Phylogenetic analysis suggested that CpAOX is a mitochondrial-type AOX, possibly derived from mitochondrial endosymbiont gene transfer. The recombinant enzyme expressed in Escherichia coli showed quinol oxidase activity. This activity was insensitive to cyanide and highly sensitive to ascofuranone, a specific inhibitor of trypanosome AOX.
Collapse
Affiliation(s)
- Takashi Suzuki
- Department of Molecular Parasitology, Nagoya City University, Graduate School of Medical Sciences, Nagoya 467-8601, Japan
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
46
|
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]
|
47
|
Finnegan PM, Umbach AL, Wilce JA. Prokaryotic origins for the mitochondrial alternative oxidase and plastid terminal oxidase nuclear genes. FEBS Lett 2003; 555:425-30. [PMID: 14675750 DOI: 10.1016/s0014-5793(03)01309-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The mitochondrial alternative oxidase is a diiron carboxylate quinol oxidase (Dox) found in plants and some fungi and protists, but not animals. The plastid terminal oxidase is distantly related to alternative oxidase and is most likely also a Dox protein. Database searches revealed that the alpha-proteobacterium Novosphingobium aromaticivorans and the cyanobacteria Nostoc sp. PCC7120, Synechococcus sp. WH8102 and Prochlorococcus marinus subsp. pastoris CCMP1378 each possess a Dox homolog. Each prokaryotic protein conforms to the current structural models of the Dox active site and phylogenetic analyses suggest that the eukaryotic Dox genes arose from an ancestral prokaryotic gene.
Collapse
Affiliation(s)
- Patrick M Finnegan
- Plant Molecular Biology Group and School of Plant Biology, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
| | | | | |
Collapse
|
48
|
Josse EM, Alcaraz JP, Labouré AM, Kuntz M. In vitro characterization of a plastid terminal oxidase (PTOX). EUROPEAN JOURNAL OF BIOCHEMISTRY 2003; 270:3787-94. [PMID: 12950262 DOI: 10.1046/j.1432-1033.2003.03766.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The plastid terminal oxidase (PTOX) encoded by the Arabidopsis IMMUTANS gene was expressed in Escherichia coli cells and its quinone/oxygen oxidoreductase activity monitored in isolated bacterial membranes using NADH as an electron donor. Specificity for plastoquinone was observed. Neither ubiquinone, duroquinone, phylloquinone nor benzoquinone could substitute for plastoquinone in this assay. However, duroquinol (fully reduced chemically) was an accepted substrate. Iron is also required and cannot be substituted by Cu(2+), Zn(2+) or Mn(2+). This plastoquinol oxidase activity is independent of temperature over the 15-40 degrees C range but increases with pH (from 5.5 to 9.0). Unlike higher plant mitochondrial alternative oxidases, to which PTOX shows sequence similarity (but also differences, especially in a putative quinone binding site and in cysteine conservation), PTOX activity does not appear to be regulated by pyruvate or any other tested sugar, nor by AMP. Its activity decreases, however, with increasing salt (NaCl or KCl) concentration. Various quinone analogues were tested for their inhibitory activity on PTOX. Pyrogallol analogues were found to be inhibitors, especially octyl gallate (I50 = 0.4 microM ) that appears far more potent than propyl gallate or gallic acid. Thus, octyl gallate is a useful inhibitor for future in vivo or in organello studies aimed at studying the roles of PTOX in chlororespiration and as a cofactor for carotenoid biosynthesis.
Collapse
|
49
|
Stenmark P, Nordlund P. A prokaryotic alternative oxidase present in the bacteriumNovosphingobium aromaticivorans. FEBS Lett 2003; 552:189-92. [PMID: 14527685 DOI: 10.1016/s0014-5793(03)00920-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The alternative oxidase (AOX) is a terminal oxidase present in the respiratory chain of all plants as well as some yeasts and trypanosomes, but has not previously been found in a prokaryote. We have identified an AOX homologue in Novosphingobium aromaticivorans, the first AOX found in a prokaryote. We have cloned the gene for the N. aromaticivorans AOX and showed it to have a terminal oxidase activity when heterologously expressed in Escherichia coli. We have also shown that this novel AOX is expressed in N. aromaticivorans cells, and that its expression level is greatly influenced by the oxygen level and carbon source of the growth media.
Collapse
Affiliation(s)
- Pål Stenmark
- Department of Biochemistry and Biophysics, Stockholm University, Roslagstullsbacken 15, Albanova University Center, SE-10691 Stockholm, Sweden
| | | |
Collapse
|
50
|
Alternative oxidase present in procyclic Trypanosoma brucei may act to lower the mitochondrial production of superoxide. Arch Biochem Biophys 2003; 414:294-302. [PMID: 12781782 DOI: 10.1016/s0003-9861(03)00196-6] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The mitochondrial electron transfer chain present in the procyclic form of the African trypanosome Trypanosoma brucei contains both cytochrome c oxidase and an alternative oxidase (TAO) as terminal oxidases that reduce oxygen to water. By contrast, the electron transfer chain of the primitive mitochondrion present in the bloodstream form of T. brucei contains only TAO as the terminal oxidase. TAO functions in the bloodstream forms to oxidize the ubiquinol produced by the glycerol-3-phosphate shuttle that results in the oxidation of the reduced nicotinamide adenine dinucleotide phosphate produced by glycolysis. The function, however, of TAO in the procyclic forms is unknown. In this study, we found that inhibition of TAO by the specific inhibitor salicylhydroxamic acid stimulates the formation of reactive oxygen species (ROS) in trypanosome mitochondria, resulting in mitochondrial alteration and increased oxidation of cellular proteins. Moreover, the activity and protein content of TAO in procyclic trypanosomes were increased when cells were incubated in the presence of hydrogen peroxide or antimycin A, the cytochrome bc1 complex inhibitor, which also results in increased ROS production. We suggest that one function of TAO in procyclic cells may be to prevent ROS production by removing excess reducing equivalents and transferring them to oxygen.
Collapse
|