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Minguillón S, Fischer-Schrader K, Pérez-Rontomé C, Matamoros MA, Becana M. The enigmatic enzyme 'amidoxime reducing component' of Lotus japonicus. Characterization, expression, activity in plant tissues, and proposed role as a nitric oxide-forming nitrite reductase. PHYSIOLOGIA PLANTARUM 2024; 176:e14438. [PMID: 39054574 DOI: 10.1111/ppl.14438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 06/05/2024] [Accepted: 06/13/2024] [Indexed: 07/27/2024]
Abstract
Human mitochondria contain a molybdoprotein capable of reducing amidoximes using cytochrome b5/cytochrome b5 reductase (Cb/CbR). This 'amidoxime reducing component' (ARC) also reduces nitrite to nitric oxide (NO). In the plant kingdom, distinct functions have been suggested for ARCs. Thus, the single ARC of Chlamydomonas reinhardtii (crARC) reduces nitrite to NO by taking electrons from nitrate reductase (NR). Therefore, it was proposed that a dual NR/crARC system can generate NO under physiological conditions and the crARC was renamed to 'NO-forming nitrite reductase' (NOFNiR). In contrast to this, the two ARC enzymes from Arabidopsis thaliana were not found to produce NO in vitro at physiological nitrite concentrations, suggesting a different, as yet unknown, function in vascular plants. Here, we have investigated the two ARCs of Lotus japonicus (LjARCs) to shed light on this controversy and to examine, for the first time, the distribution of ARCs in plant tissues. The LjARCs are localized in the cytosol and their activities and catalytic efficiencies, which are much higher than those of A. thaliana, are consistent with a role as NOFNiR. LjARCs are prone to S-nitrosylation in vitro by S-nitrosoglutathione and this post-translational modification drastically inhibits their activities. The enzymes are mainly expressed in flowers, seeds and pods, but are absent in nodules. LjARCs are active with NR and Cb/CbR as electron-transferring systems. However, the LjNR mRNA levels in seeds and pods are negligible, whereas our proteomic analyses show that pods contain the two ARCs, Cb and CbR. We conclude that LjARCs may play a role as NOFNiR by receiving electrons from the Cb/CbR system but do not act in combination with NR.
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Affiliation(s)
- Samuel Minguillón
- Departamento de Biología Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas (CSIC), Zaragoza, Spain
| | - Katrin Fischer-Schrader
- Institute of Biochemistry, Department of Chemistry and Biochemistry, University of Cologne, Germany
| | - Carmen Pérez-Rontomé
- Departamento de Biología Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas (CSIC), Zaragoza, Spain
| | - Manuel A Matamoros
- Departamento de Biología Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas (CSIC), Zaragoza, Spain
| | - Manuel Becana
- Departamento de Biología Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas (CSIC), Zaragoza, Spain
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2
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Weber JN, Minner-Meinen R, Kaufholdt D. The Mechanisms of Molybdate Distribution and Homeostasis with Special Focus on the Model Plant Arabidopsis thaliana. Molecules 2023; 29:40. [PMID: 38202623 PMCID: PMC10780190 DOI: 10.3390/molecules29010040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 12/08/2023] [Accepted: 12/15/2023] [Indexed: 01/12/2024] Open
Abstract
This review article deals with the pathways of cellular and global molybdate distribution in plants, especially with a full overview for the model plant Arabidopsis thaliana. In its oxidized state as bioavailable molybdate, molybdenum can be absorbed from the environment. Especially in higher plants, molybdenum is indispensable as part of the molybdenum cofactor (Moco), which is responsible for functionality as a prosthetic group in a variety of essential enzymes like nitrate reductase and sulfite oxidase. Therefore, plants need mechanisms for molybdate import and transport within the organism, which are accomplished via high-affinity molybdate transporter (MOT) localized in different cells and membranes. Two different MOT families were identified. Legumes like Glycine max or Medicago truncatula have an especially increased number of MOT1 family members for supplying their symbionts with molybdate for nitrogenase activity. In Arabidopsis thaliana especially, the complete pathway followed by molybdate through the plant is traceable. Not only the uptake from soil by MOT1.1 and its distribution to leaves, flowers, and seeds by MOT2-family members was identified, but also that inside the cell. the transport trough the cytoplasm and the vacuolar storage mechanisms depending on glutathione were described. Finally, supplying the Moco biosynthesis complex by MOT1.2 and MOT2.1 was demonstrated.
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Affiliation(s)
| | | | - David Kaufholdt
- Institut für Pflanzenbiologie, Technische Universität Braunschweig, Humboldtstrasse 1, D-38106 Braunschweig, Germany
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3
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Struwe MA, Scheidig AJ, Clement B. The mitochondrial amidoxime reducing component-from prodrug-activation mechanism to drug-metabolizing enzyme and onward to drug target. J Biol Chem 2023; 299:105306. [PMID: 37778733 PMCID: PMC10637980 DOI: 10.1016/j.jbc.2023.105306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 09/17/2023] [Accepted: 09/24/2023] [Indexed: 10/03/2023] Open
Abstract
The mitochondrial amidoxime-reducing component (mARC) is one of five known molybdenum enzymes in eukaryotes. mARC belongs to the MOSC domain superfamily, a large group of so far poorly studied molybdoenzymes. mARC was initially discovered as the enzyme activating N-hydroxylated prodrugs of basic amidines but has since been shown to also reduce a variety of other N-oxygenated compounds, for example, toxic nucleobase analogs. Under certain circumstances, mARC might also be involved in reductive nitric oxide synthesis through reduction of nitrite. Recently, mARC enzymes have received a lot of attention due to their apparent involvement in lipid metabolism and, in particular, because many genome-wide association studies have shown a common variant of human mARC1 to have a protective effect against liver disease. The mechanism linking mARC enzymes with lipid metabolism remains unknown. Here, we give a comprehensive overview of what is currently known about mARC enzymes, their substrates, structure, and apparent involvement in human disease.
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Affiliation(s)
- Michel A Struwe
- Zoologisches Institut - Strukturbiologie, Christian-Albrechts-Universität Kiel, Kiel, Germany; Pharmazeutisches Institut, Christian-Albrechts-Universität Kiel, Kiel, Germany.
| | - Axel J Scheidig
- Zoologisches Institut - Strukturbiologie, Christian-Albrechts-Universität Kiel, Kiel, Germany
| | - Bernd Clement
- Pharmazeutisches Institut, Christian-Albrechts-Universität Kiel, Kiel, Germany
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4
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Rixen S, Indorf PM, Kubitza C, Struwe MA, Klopp C, Scheidig AJ, Kunze T, Clement B. Reduction of Hydrogen Peroxide by Human Mitochondrial Amidoxime Reducing Component Enzymes. Molecules 2023; 28:6384. [PMID: 37687214 PMCID: PMC10489706 DOI: 10.3390/molecules28176384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 08/23/2023] [Accepted: 08/29/2023] [Indexed: 09/10/2023] Open
Abstract
The mitochondrial amidoxime reducing component (mARC) is a human molybdoenzyme known to catalyze the reduction of various N-oxygenated substrates. The physiological function of mARC enzymes, however, remains unknown. In this study, we examine the reduction of hydrogen peroxide (H2O2) by the human mARC1 and mARC2 enzymes. Furthermore, we demonstrate an increased sensitivity toward H2O2 for HEK-293T cells with an MTARC1 knockout, which implies a role of mARC enzymes in the cellular response to oxidative stress. H2O2 is a reactive oxygen species (ROS) formed in all living cells involved in many physiological processes. Furthermore, H2O2 constitutes the first mARC substrate without a nitrogen-oxygen bond, implying that mARC enzymes may have a substrate spectrum going beyond the previously examined N-oxygenated compounds.
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Affiliation(s)
- Sophia Rixen
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Kiel University, 24118 Kiel, Germany; (S.R.); (P.M.I.); (M.A.S.); (C.K.); (T.K.)
| | - Patrick M. Indorf
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Kiel University, 24118 Kiel, Germany; (S.R.); (P.M.I.); (M.A.S.); (C.K.); (T.K.)
| | - Christian Kubitza
- Department of Structural Biology, Zoological Institute, Kiel University, 24118 Kiel, Germany; (C.K.); (A.J.S.)
| | - Michel A. Struwe
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Kiel University, 24118 Kiel, Germany; (S.R.); (P.M.I.); (M.A.S.); (C.K.); (T.K.)
- Department of Structural Biology, Zoological Institute, Kiel University, 24118 Kiel, Germany; (C.K.); (A.J.S.)
| | - Cathrin Klopp
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Kiel University, 24118 Kiel, Germany; (S.R.); (P.M.I.); (M.A.S.); (C.K.); (T.K.)
- Department of Structural Biology, Zoological Institute, Kiel University, 24118 Kiel, Germany; (C.K.); (A.J.S.)
| | - Axel J. Scheidig
- Department of Structural Biology, Zoological Institute, Kiel University, 24118 Kiel, Germany; (C.K.); (A.J.S.)
| | - Thomas Kunze
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Kiel University, 24118 Kiel, Germany; (S.R.); (P.M.I.); (M.A.S.); (C.K.); (T.K.)
| | - Bernd Clement
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Kiel University, 24118 Kiel, Germany; (S.R.); (P.M.I.); (M.A.S.); (C.K.); (T.K.)
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5
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Tejada-Jimenez M, Leon-Miranda E, Llamas A. Chlamydomonas reinhardtii-A Reference Microorganism for Eukaryotic Molybdenum Metabolism. Microorganisms 2023; 11:1671. [PMID: 37512844 PMCID: PMC10385300 DOI: 10.3390/microorganisms11071671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 06/19/2023] [Accepted: 06/23/2023] [Indexed: 07/30/2023] Open
Abstract
Molybdenum (Mo) is vital for the activity of a small but essential group of enzymes called molybdoenzymes. So far, specifically five molybdoenzymes have been discovered in eukaryotes: nitrate reductase, sulfite oxidase, xanthine dehydrogenase, aldehyde oxidase, and mARC. In order to become biologically active, Mo must be chelated to a pterin, forming the so-called Mo cofactor (Moco). Deficiency or mutation in any of the genes involved in Moco biosynthesis results in the simultaneous loss of activity of all molybdoenzymes, fully or partially preventing the normal development of the affected organism. To prevent this, the different mechanisms involved in Mo homeostasis must be finely regulated. Chlamydomonas reinhardtii is a unicellular, photosynthetic, eukaryotic microalga that has produced fundamental advances in key steps of Mo homeostasis over the last 30 years, which have been extrapolated to higher organisms, both plants and animals. These advances include the identification of the first two molybdate transporters in eukaryotes (MOT1 and MOT2), the characterization of key genes in Moco biosynthesis, the identification of the first enzyme that protects and transfers Moco (MCP1), the first characterization of mARC in plants, and the discovery of the crucial role of the nitrate reductase-mARC complex in plant nitric oxide production. This review aims to provide a comprehensive summary of the progress achieved in using C. reinhardtii as a model organism in Mo homeostasis and to propose how this microalga can continue improving with the advancements in this field in the future.
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Affiliation(s)
- Manuel Tejada-Jimenez
- Department of Biochemistry and Molecular Biology, Campus de Rabanales and Campus Internacional de Excelencia Agroalimentario (CeiA3), Edificio Severo Ochoa, University of Córdoba, 14071 Córdoba, Spain
| | - Esperanza Leon-Miranda
- Department of Biochemistry and Molecular Biology, Campus de Rabanales and Campus Internacional de Excelencia Agroalimentario (CeiA3), Edificio Severo Ochoa, University of Córdoba, 14071 Córdoba, Spain
| | - Angel Llamas
- Department of Biochemistry and Molecular Biology, Campus de Rabanales and Campus Internacional de Excelencia Agroalimentario (CeiA3), Edificio Severo Ochoa, University of Córdoba, 14071 Córdoba, Spain
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6
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Kalimuthu P, Harmer JR, Baldauf M, Hassan AH, Kruse T, Bernhardt PV. Catalytic electrochemistry of the bacterial Molybdoenzyme YcbX. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148579. [PMID: 35640667 DOI: 10.1016/j.bbabio.2022.148579] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 05/02/2022] [Accepted: 05/25/2022] [Indexed: 06/15/2023]
Abstract
Molybdenum-dependent enzymes that can reduce N-hydroxylated substrates (e.g. N-hydroxyl-purines, amidoximes) are found in bacteria, plants and vertebrates. They are involved in the conversion of a wide range of N-hydroxylated organic compounds into their corresponding amines, and utilize various redox proteins (cytochrome b5, cyt b5 reductase, flavin reductase) to deliver reducing equivalents to the catalytic centre. Here we present catalytic electrochemistry of the bacterial enzyme YcbX from Escherichia coli utilizing the synthetic electron transfer mediator methyl viologen (MV2+). The electrochemically reduced form (MV+.) acts as an effective electron donor for YcbX. To immobilize YcbX on a glassy carbon electrode, a facile protein crosslinking approach was used with the crosslinker glutaraldehyde (GTA). The YcbX-modified electrode showed a catalytic response for the reduction of a broad range of N-hydroxylated substrates. The catalytic activity of YcbX was examined at different pH values exhibiting an optimum at pH 7.5 and a bell-shaped pH profile with deactivation through deprotonation (pKa1 9.1) or protonation (pKa2 6.1). Electrochemical simulation was employed to obtain new biochemical data for YcbX, in its reaction with methyl viologen and the organic substrates 6-N-hydroxylaminopurine (6-HAP) and benzamidoxime (BA).
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Affiliation(s)
- Palraj Kalimuthu
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane 4072, Australia
| | - Jeffrey R Harmer
- Centre for Advanced Imaging, University of Queensland, Brisbane 4072, Australia
| | - Milena Baldauf
- Department of Plant Biology, Technische Universitaet, Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany
| | - Ahmed H Hassan
- Department of Plant Biology, Technische Universitaet, Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany
| | - Tobias Kruse
- Department of Plant Biology, Technische Universitaet, Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany
| | - Paul V Bernhardt
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane 4072, Australia.
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Tejada-Jimenez M, Llamas A, Galván A, Fernández E. Role of Nitrate Reductase in NO Production in Photosynthetic Eukaryotes. PLANTS 2019; 8:plants8030056. [PMID: 30845759 PMCID: PMC6473468 DOI: 10.3390/plants8030056] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 02/06/2019] [Accepted: 02/08/2019] [Indexed: 12/20/2022]
Abstract
Nitric oxide is a gaseous secondary messenger that is critical for proper cell signaling and plant survival when exposed to stress. Nitric oxide (NO) synthesis in plants, under standard phototrophic oxygenic conditions, has long been a very controversial issue. A few algal strains contain NO synthase (NOS), which appears to be absent in all other algae and land plants. The experimental data have led to the hypothesis that molybdoenzyme nitrate reductase (NR) is the main enzyme responsible for NO production in most plants. Recently, NR was found to be a necessary partner in a dual system that also includes another molybdoenzyme, which was renamed NO-forming nitrite reductase (NOFNiR). This enzyme produces NO independently of the molybdenum center of NR and depends on the NR electron transport chain from NAD(P)H to heme. Under the circumstances in which NR is not present or active, the existence of another NO-forming system that is similar to the NOS system would account for NO production and NO effects. PII protein, which senses and integrates the signals of the C–N balance in the cell, likely has an important role in organizing cell responses. Here, we critically analyze these topics.
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Affiliation(s)
- Manuel Tejada-Jimenez
- Departamento de Bioquímica y Biología Molecular, Campus de Rabanales y Campus Internacional de Excelencia Agroalimentario (CeiA3), Edif. Severo Ochoa, Universidad de Córdoba, 14071 Córdoba, Spain.
| | - Angel Llamas
- Departamento de Bioquímica y Biología Molecular, Campus de Rabanales y Campus Internacional de Excelencia Agroalimentario (CeiA3), Edif. Severo Ochoa, Universidad de Córdoba, 14071 Córdoba, Spain.
| | - Aurora Galván
- Departamento de Bioquímica y Biología Molecular, Campus de Rabanales y Campus Internacional de Excelencia Agroalimentario (CeiA3), Edif. Severo Ochoa, Universidad de Córdoba, 14071 Córdoba, Spain.
| | - Emilio Fernández
- Departamento de Bioquímica y Biología Molecular, Campus de Rabanales y Campus Internacional de Excelencia Agroalimentario (CeiA3), Edif. Severo Ochoa, Universidad de Córdoba, 14071 Córdoba, Spain.
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8
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From the Eukaryotic Molybdenum Cofactor Biosynthesis to the Moonlighting Enzyme mARC. Molecules 2018; 23:molecules23123287. [PMID: 30545001 PMCID: PMC6321594 DOI: 10.3390/molecules23123287] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 11/23/2018] [Accepted: 12/05/2018] [Indexed: 12/20/2022] Open
Abstract
All eukaryotic molybdenum (Mo) enzymes contain in their active site a Mo Cofactor (Moco), which is formed by a tricyclic pyranopterin with a dithiolene chelating the Mo atom. Here, the eukaryotic Moco biosynthetic pathway and the eukaryotic Moco enzymes are overviewed, including nitrate reductase (NR), sulfite oxidase, xanthine oxidoreductase, aldehyde oxidase, and the last one discovered, the moonlighting enzyme mitochondrial Amidoxime Reducing Component (mARC). The mARC enzymes catalyze the reduction of hydroxylated compounds, mostly N-hydroxylated (NHC), but as well of nitrite to nitric oxide, a second messenger. mARC shows a broad spectrum of NHC as substrates, some are prodrugs containing an amidoxime structure, some are mutagens, such as 6-hydroxylaminepurine and some others, which most probably will be discovered soon. Interestingly, all known mARC need the reducing power supplied by different partners. For the NHC reduction, mARC uses cytochrome b5 and cytochrome b5 reductase, however for the nitrite reduction, plant mARC uses NR. Despite the functional importance of mARC enzymatic reactions, the structural mechanism of its Moco-mediated catalysis is starting to be revealed. We propose and compare the mARC catalytic mechanism of nitrite versus NHC reduction. By using the recently resolved structure of a prokaryotic MOSC enzyme, from the mARC protein family, we have modeled an in silico three-dimensional structure of a eukaryotic homologue.
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9
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Crystal structure of human mARC1 reveals its exceptional position among eukaryotic molybdenum enzymes. Proc Natl Acad Sci U S A 2018; 115:11958-11963. [PMID: 30397129 DOI: 10.1073/pnas.1808576115] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Biotransformation enzymes ensure a viable homeostasis by regulating reversible cycles of oxidative and reductive reactions. The metabolism of nitrogen-containing compounds is of high pharmaceutical and toxicological relevance because N-oxygenated metabolites derived from reactions mediated by cytochrome P450 enzymes or flavin-dependent monooxygenases are in some cases highly toxic or mutagenic. The molybdenum-dependent mitochondrial amidoxime-reducing component (mARC) was found to be an extremely efficient counterpart, which is able to reduce the full range of N-oxygenated compounds and thereby mediates detoxification reactions. However, the 3D structure of this enzyme was unknown. Here we present the high-resolution crystal structure of human mARC. We give detailed insight into the coordination of its molybdenum cofactor (Moco), the catalytic mechanism, and its ability to reduce a wide range of N-oxygenated compounds. The identification of two key residues will allow future discrimination between mARC paralogs and ensure correct annotation. Since our structural findings contradict in silico predictions that are currently made by online databases, we propose domain definitions for members of the superfamily of Moco sulfurase C-terminal (MOSC) domain-containing proteins. Furthermore, we present evidence for an evolutionary role of mARC for the emergence of the xanthine oxidase protein superfamily. We anticipate the hereby presented crystal structure to be a starting point for future descriptions of MOSC proteins, which are currently poorly structurally characterized.
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Batyrshina Z, Yergaliyev TM, Nurbekova Z, Moldakimova NA, Masalimov ZK, Sagi M, Omarov RT. Differential influence of molybdenum and tungsten on the growth of barley seedlings and the activity of aldehyde oxidase under salinity. JOURNAL OF PLANT PHYSIOLOGY 2018; 228:189-196. [PMID: 29960143 DOI: 10.1016/j.jplph.2018.06.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 06/07/2018] [Accepted: 06/08/2018] [Indexed: 06/08/2023]
Abstract
The influence of molybdenum, tungsten on germination and growth of barley Hordeum vulgare L. was studied. Results of this study revealed the differential effect of heavy metals on seedlings growth. Exogenous molybdenum treatment stimulated the growth of seedlings. The addition of the metal significantly stimulated root elongation. Contrastingly, the addition of tungsten resulted in increased seed germination and inhibits the growth of seedlings. The negative effect of tungsten on the growth of barley was more profound for roots of plants. In addition, the influence of metals on the growth of plants was also tested in saline conditions. It is shown that under salinity stress plant growth drastically decreased in presence of tungsten. Results of this study showed that activity of molybdenum-containing aldehyde oxidase (AO; EC 1.2.3.1) was also significantly affected by metals. The activity of AO in leaves and roots enhanced with increasing concentrations of molybdate, while tungstate treatment inhibited the enzyme activity. Perhaps, the differential influence of molybdenum and tungsten on the growth of barley is a direct effect of metals on aldehyde oxidase activity in plants. Moreover, the intense negative effect of tungsten treatment on barley growth under salinity conditions emphasizes an important role of aldehyde oxidase in plant resistance to stress factors.
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Affiliation(s)
- Zhaniya Batyrshina
- Department of Biotechnology and Microbiology, L.N. Gumilyov Eurasian University, Astana, Kazakhstan
| | - Timur M Yergaliyev
- Department of Biotechnology and Microbiology, L.N. Gumilyov Eurasian University, Astana, Kazakhstan; Department of Biology and Chemistry, A. Baitursynov Kostanay State University, Kostanay, Kazakhstan
| | - Zhadyrassyn Nurbekova
- Department of Biotechnology and Microbiology, L.N. Gumilyov Eurasian University, Astana, Kazakhstan; Biostress Research Laboratory, J. Blaustein Institute for Desert Research, Ben-Gurion University of the Negev, Sede Boqer, Israel
| | - Nazira A Moldakimova
- Department of Biotechnology and Microbiology, L.N. Gumilyov Eurasian University, Astana, Kazakhstan
| | - Zhaksylyk K Masalimov
- Department of Biotechnology and Microbiology, L.N. Gumilyov Eurasian University, Astana, Kazakhstan
| | - Moshe Sagi
- Biostress Research Laboratory, J. Blaustein Institute for Desert Research, Ben-Gurion University of the Negev, Sede Boqer, Israel
| | - Rustem T Omarov
- Department of Biotechnology and Microbiology, L.N. Gumilyov Eurasian University, Astana, Kazakhstan.
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Llamas A, Chamizo-Ampudia A, Tejada-Jimenez M, Galvan A, Fernandez E. The molybdenum cofactor enzyme mARC: Moonlighting or promiscuous enzyme? Biofactors 2017; 43:486-494. [PMID: 28497908 DOI: 10.1002/biof.1362] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 03/20/2017] [Accepted: 03/28/2017] [Indexed: 12/13/2022]
Abstract
Molybdenum (Mo) is present in the active center of eukaryotic enzymes as a tricyclic pyranopterin chelate compound forming the Mo Cofactor (Moco). Four Moco containing enzymes are known in eukaryotes, nitrate reductase (NR), sulfite oxidase (SO), xanthine oxidoreductase (XOR), and aldehyde oxidase (AO). A fifth Moco enzyme has been recently identified. Because of the ability of this enzyme to convert by reduction several amidoximes prodrugs into their active amino forms, it was named mARC (mitochondrial Amidoxime Reducing Component). This enzyme is also able to catalyze the reduction of a broad range of N-hydroxylated compounds (NHC) as the base analogue 6-hydroxylaminopurine (HAP), as well as nitrite to nitric oxide (NO). All the mARC proteins need reducing power that is supplied by other proteins. The human and plants mARC proteins require a Cytochrome b5 (Cytb5) and a Cytochrome b5 reductase (Cytb5-R) to form an electron transfer chain from NADH to the NHC. Recently, plant mARC proteins were shown to be implicated in the reduction of nitrite to NO, and it was proposed that the electrons required for the reaction were supplied by NR instead of Cytochrome b5 components. This newly characterized mARC activity was termed NO Forming Nitrite Reductase (NOFNiR). Moonlighting proteins form a special class of multifunctional enzymes that can perform more than one function; if the extra function is not physiologically relevant, they are called promiscuous enzymes. In this review, we summarize the current knowledge on the mARC protein, and we propose that mARC is a new moonlighting enzyme. © 2017 BioFactors, 43(4):486-494, 2017.
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Affiliation(s)
- Angel Llamas
- Dpto. de Bioquímica y Biología Molecular, Campus de Rabanales y Campus Internacional de Excelencia Agroalimentario (CeiA3), Edif. Severo Ochoa, Universidad de Córdoba, Spain
| | - Alejandro Chamizo-Ampudia
- Dpto. de Bioquímica y Biología Molecular, Campus de Rabanales y Campus Internacional de Excelencia Agroalimentario (CeiA3), Edif. Severo Ochoa, Universidad de Córdoba, Spain
| | - Manuel Tejada-Jimenez
- Dpto. de Bioquímica y Biología Molecular, Campus de Rabanales y Campus Internacional de Excelencia Agroalimentario (CeiA3), Edif. Severo Ochoa, Universidad de Córdoba, Spain
| | - Aurora Galvan
- Dpto. de Bioquímica y Biología Molecular, Campus de Rabanales y Campus Internacional de Excelencia Agroalimentario (CeiA3), Edif. Severo Ochoa, Universidad de Córdoba, Spain
| | - Emilio Fernandez
- Dpto. de Bioquímica y Biología Molecular, Campus de Rabanales y Campus Internacional de Excelencia Agroalimentario (CeiA3), Edif. Severo Ochoa, Universidad de Córdoba, Spain
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Plouviez M, Wheeler D, Shilton A, Packer MA, McLenachan PA, Sanz-Luque E, Ocaña-Calahorro F, Fernández E, Guieysse B. The biosynthesis of nitrous oxide in the green alga Chlamydomonas reinhardtii. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 91:45-56. [PMID: 28333392 DOI: 10.1111/tpj.13544] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 02/27/2017] [Accepted: 03/17/2017] [Indexed: 05/13/2023]
Abstract
Over the last decades, several studies have reported emissions of nitrous oxide (N2 O) from microalgal cultures and aquatic ecosystems characterized by a high level of algal activity (e.g. eutrophic lakes). As N2 O is a potent greenhouse gas and an ozone-depleting pollutant, these findings suggest that large-scale cultivation of microalgae (and possibly, natural eutrophic ecosystems) could have a significant environmental impact. Using the model unicellular microalga Chlamydomonas reinhardtii, this study was conducted to investigate the molecular basis of microalgal N2 O synthesis. We report that C. reinhardtii supplied with nitrite (NO2- ) under aerobic conditions can reduce NO2- into nitric oxide (NO) using either a mitochondrial cytochrome c oxidase (COX) or a dual enzymatic system of nitrate reductase (NR) and amidoxime-reducing component, and that NO is subsequently reduced into N2 O by the enzyme NO reductase (NOR). Based on experimental evidence and published literature, we hypothesize that when nitrate (NO3- ) is the main Nitrogen source and the intracellular concentration of NO2- is low (i.e. under physiological conditions), microalgal N2 O synthesis involves the reduction of NO3- to NO2- by NR followed by the reduction of NO2- to NO by the dual system involving NR. This microalgal N2 O pathway has broad implications for environmental science and algal biology because the pathway of NO3- assimilation is conserved among microalgae, and because its regulation may involve NO.
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Affiliation(s)
- Maxence Plouviez
- School of Engineering and Advanced Technology, Massey University, Private Bag 11222, Palmerston North, New Zealand
| | - David Wheeler
- Institute of Fundamental Sciences, Massey University, Private Bag 11222, Palmerston North, New Zealand
| | - Andy Shilton
- School of Engineering and Advanced Technology, Massey University, Private Bag 11222, Palmerston North, New Zealand
| | - Michael A Packer
- Cawthron Institute, 98 Halifax Street, Nelson, 7010, New Zealand
| | - Patricia A McLenachan
- Institute of Fundamental Sciences, Massey University, Private Bag 11222, Palmerston North, New Zealand
| | - Emanuel Sanz-Luque
- Department of Biochemistry and Molecular Biology, University of Cordoba, Campus de Rabanales, Campus de excelencia internacional (CeiA3), Edif. Severo Ochoa, Córdoba, 14071, Spain
| | - Francisco Ocaña-Calahorro
- Department of Biochemistry and Molecular Biology, University of Cordoba, Campus de Rabanales, Campus de excelencia internacional (CeiA3), Edif. Severo Ochoa, Córdoba, 14071, Spain
| | - Emilio Fernández
- Department of Biochemistry and Molecular Biology, University of Cordoba, Campus de Rabanales, Campus de excelencia internacional (CeiA3), Edif. Severo Ochoa, Córdoba, 14071, Spain
| | - Benoit Guieysse
- School of Engineering and Advanced Technology, Massey University, Private Bag 11222, Palmerston North, New Zealand
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Calatrava V, Chamizo-Ampudia A, Sanz-Luque E, Ocaña-Calahorro F, Llamas A, Fernandez E, Galvan A. How Chlamydomonas handles nitrate and the nitric oxide cycle. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:2593-2602. [PMID: 28201747 DOI: 10.1093/jxb/erw507] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The green alga Chlamydomonas is a valuable model system capable of assimilating different forms of nitrogen (N). Nitrate (NO3-) has a relevant role in plant-like organisms, first as a nitrogen source for growth and second as a signalling molecule. Several modules are necessary for Chlamydomonas to handle nitrate, including transporters, nitrate reductase (NR), nitrite reductase (NiR), GS/GOGAT enzymes for ammonium assimilation, and regulatory protein(s). Transporters provide a first step for influx/efflux, homeostasis, and sensing of nitrate; and NIT2 is the key transcription factor (RWP-RK) for mediating the nitrate-dependent activation of a number of genes. Here, we review how NR participates in the cycle NO3- →NO2- →NO →NO3-. NR uses the partner protein amidoxime-reducing component/nitric oxide-forming nitrite reductase (ARC/NOFNiR) for the conversion of nitrite (NO2-) into nitric oxide (NO). It also uses the truncated haemoglobin THB1 in the conversion of nitric oxide to nitrate. Nitric oxide is a negative signal for nitrate assimilation; it inhibits the activity and expression of high-affinity nitrate/nitrite transporters and NR. During this cycle, the positive signal of nitrate is transformed into the negative signal of nitric oxide, which can then be converted back into nitrate. Thus, NR is back in the spotlight as a strategic regulator of the nitric oxide cycle and the nitrate assimilation pathway.
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Affiliation(s)
- Victoria Calatrava
- Departamento de Bioquímica y Biología Molecular, Campus de Rabanales y Campus Internacional de Excelencia Agroalimentario (CeiA3), Edif. Severo Ochoa, Universidad de Córdoba, Spain
| | - Alejandro Chamizo-Ampudia
- Departamento de Bioquímica y Biología Molecular, Campus de Rabanales y Campus Internacional de Excelencia Agroalimentario (CeiA3), Edif. Severo Ochoa, Universidad de Córdoba, Spain
| | - Emanuel Sanz-Luque
- Departamento de Bioquímica y Biología Molecular, Campus de Rabanales y Campus Internacional de Excelencia Agroalimentario (CeiA3), Edif. Severo Ochoa, Universidad de Córdoba, Spain
| | - Francisco Ocaña-Calahorro
- Departamento de Bioquímica y Biología Molecular, Campus de Rabanales y Campus Internacional de Excelencia Agroalimentario (CeiA3), Edif. Severo Ochoa, Universidad de Córdoba, Spain
| | - Angel Llamas
- Departamento de Bioquímica y Biología Molecular, Campus de Rabanales y Campus Internacional de Excelencia Agroalimentario (CeiA3), Edif. Severo Ochoa, Universidad de Córdoba, Spain
| | - Emilio Fernandez
- Departamento de Bioquímica y Biología Molecular, Campus de Rabanales y Campus Internacional de Excelencia Agroalimentario (CeiA3), Edif. Severo Ochoa, Universidad de Córdoba, Spain
| | - Aurora Galvan
- Departamento de Bioquímica y Biología Molecular, Campus de Rabanales y Campus Internacional de Excelencia Agroalimentario (CeiA3), Edif. Severo Ochoa, Universidad de Córdoba, Spain
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Study of Different Variants of Mo Enzyme crARC and the Interaction with Its Partners crCytb5-R and crCytb5-1. Int J Mol Sci 2017; 18:ijms18030670. [PMID: 28335548 PMCID: PMC5372681 DOI: 10.3390/ijms18030670] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 03/07/2017] [Accepted: 03/10/2017] [Indexed: 12/30/2022] Open
Abstract
The mARC (mitochondrial Amidoxime Reducing Component) proteins are recently discovered molybdenum (Mo) Cofactor containing enzymes. They are involved in the reduction of several N-hydroxylated compounds (NHC) and nitrite. Some NHC are prodrugs containing an amidoxime structure or mutagens such as 6-hydroxylaminopurine (HAP). We have studied this protein in the green alga Chlamydomonas reinhardtii (crARC). Interestingly, all the ARC proteins need the reducing power supplied by other proteins. It is known that crARC requires a cytochrome b₅ (crCytb5-1) and a cytochrome b₅ reductase (crCytb5-R) that form an electron transport chain from NADH to the substrates. Here, we have investigated NHC reduction by crARC, the interaction with its partners and the function of important conserved amino acids. Interactions among crARC, crCytb5-1 and crCytb5-R have been studied by size-exclusion chromatography. A protein complex between crARC, crCytb5-1 and crCytb5-R was identified. Twelve conserved crARC amino acids have been substituted by alanine by in vitro mutagenesis. We have determined that the amino acids D182, F210 and R276 are essential for NHC reduction activity, R276 is important and F210 is critical for the Mo Cofactor chelation. Finally, the crARC C-termini were shown to be involved in protein aggregation or oligomerization.
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Vigani G, Di Silvestre D, Agresta AM, Donnini S, Mauri P, Gehl C, Bittner F, Murgia I. Molybdenum and iron mutually impact their homeostasis in cucumber (Cucumis sativus) plants. THE NEW PHYTOLOGIST 2017; 213:1222-1241. [PMID: 27735062 DOI: 10.1111/nph.14214] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 08/22/2016] [Indexed: 05/22/2023]
Abstract
Molybdenum (Mo) and iron (Fe) are essential micronutrients required for crucial enzyme activities in plant metabolism. Here we investigated the existence of a mutual control of Mo and Fe homeostasis in cucumber (Cucumis sativus). Plants were grown under single or combined Mo and Fe starvation. Physiological parameters were measured, the ionomes of tissues and the ionomes and proteomes of root mitochondria were profiled, and the activities of molybdo-enzymes and the synthesis of molybdenum cofactor (Moco) were evaluated. Fe and Mo were found to affect each other's total uptake and distribution within tissues and at the mitochondrial level, with Fe nutritional status dominating over Mo homeostasis and affecting Mo availability for molybdo-enzymes in the form of Moco. Fe starvation triggered Moco biosynthesis and affected the molybdo-enzymes, with its main impact on nitrate reductase and xanthine dehydrogenase, both being involved in nitrogen assimilation and mobilization, and on the mitochondrial amidoxime reducing component. These results, together with the identification of > 100 proteins differentially expressed in root mitochondria, highlight the central role of mitochondria in the coordination of Fe and Mo homeostasis and allow us to propose the first model of the molecular interactions connecting Mo and Fe homeostasis.
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Affiliation(s)
- Gianpiero Vigani
- Department of Agricultural and Environmental Sciences, University of Milano, via Celoria 2, 20133, Milano, Italy
| | - Dario Di Silvestre
- Proteomic and Metabolomic Laboratory, Institute of Biomedical Technologies, National Research Council (ITB-CNR), via F.lli Cervi 93, 20090, Segrate (MI), Italy
| | - Anna Maria Agresta
- Proteomic and Metabolomic Laboratory, Institute of Biomedical Technologies, National Research Council (ITB-CNR), via F.lli Cervi 93, 20090, Segrate (MI), Italy
| | - Silvia Donnini
- Department of Agricultural and Environmental Sciences, University of Milano, via Celoria 2, 20133, Milano, Italy
| | - Pierluigi Mauri
- Proteomic and Metabolomic Laboratory, Institute of Biomedical Technologies, National Research Council (ITB-CNR), via F.lli Cervi 93, 20090, Segrate (MI), Italy
| | - Christian Gehl
- Institute of Horticulture Production Systems, Leibniz University of Hannover, Herrenhaeuser Str. 2, 30419, Hannover, Germany
| | - Florian Bittner
- Department of Plant Biology, Braunschweig University of Technology, Spielmannstrasse 7, 38106, Braunschweig, Germany
| | - Irene Murgia
- Department of Biosciences, University of Milano, via Celoria 26, 20133, Milano, Italy
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16
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Chamizo-Ampudia A, Sanz-Luque E, Llamas A, Galvan A, Fernandez E. Nitrate Reductase Regulates Plant Nitric Oxide Homeostasis. TRENDS IN PLANT SCIENCE 2017; 22:163-174. [PMID: 28065651 DOI: 10.1016/j.tplants.2016.12.001] [Citation(s) in RCA: 220] [Impact Index Per Article: 31.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 11/16/2016] [Accepted: 12/04/2016] [Indexed: 05/18/2023]
Abstract
Nitrate reductase (NR) is a key enzyme for nitrogen acquisition by plants, algae, yeasts, and fungi. Nitrate, its main substrate, is required for signaling and is widely distributed in diverse tissues in plants. In addition, NR has been proposed as an important enzymatic source of nitric oxide (NO). Recently, NR has been shown to play a role in NO homeostasis by supplying electrons from NAD(P)H through its diaphorase/dehydrogenase domain both to a truncated hemoglobin THB1, which scavenges NO by its dioxygenase activity, and to the molybdoenzyme NO-forming nitrite reductase (NOFNiR) that is responsible for NO synthesis from nitrite. We review how NR may play a central role in plant biology by controlling the amounts of NO, a key signaling molecule in plant cells.
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Affiliation(s)
- Alejandro Chamizo-Ampudia
- Department of Biochemistry and Molecular Biology, University of Cordoba, Campus de Rabanales, School of Sciences, Campus de Excelencia Internacional (CeiA3), Edifico Severo Ochoa, Cordoba, Spain
| | - Emanuel Sanz-Luque
- Department of Biochemistry and Molecular Biology, University of Cordoba, Campus de Rabanales, School of Sciences, Campus de Excelencia Internacional (CeiA3), Edifico Severo Ochoa, Cordoba, Spain; Present address: Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA
| | - Angel Llamas
- Department of Biochemistry and Molecular Biology, University of Cordoba, Campus de Rabanales, School of Sciences, Campus de Excelencia Internacional (CeiA3), Edifico Severo Ochoa, Cordoba, Spain
| | - Aurora Galvan
- Department of Biochemistry and Molecular Biology, University of Cordoba, Campus de Rabanales, School of Sciences, Campus de Excelencia Internacional (CeiA3), Edifico Severo Ochoa, Cordoba, Spain
| | - Emilio Fernandez
- Department of Biochemistry and Molecular Biology, University of Cordoba, Campus de Rabanales, School of Sciences, Campus de Excelencia Internacional (CeiA3), Edifico Severo Ochoa, Cordoba, Spain.
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17
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Chamizo-Ampudia A, Sanz-Luque E, Llamas Á, Ocaña-Calahorro F, Mariscal V, Carreras A, Barroso JB, Galván A, Fernández E. A dual system formed by the ARC and NR molybdoenzymes mediates nitrite-dependent NO production in Chlamydomonas. PLANT, CELL & ENVIRONMENT 2016; 39:2097-107. [PMID: 26992087 DOI: 10.1111/pce.12739] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 03/08/2016] [Accepted: 03/09/2016] [Indexed: 05/20/2023]
Abstract
Nitric oxide (NO) is a relevant signal molecule involved in many plant processes. However, the mechanisms and proteins responsible for its synthesis are scarcely known. In most photosynthetic organisms NO synthases have not been identified, and Nitrate Reductase (NR) has been proposed as the main enzymatic NO source, a process that in vitro is also catalysed by other molybdoenzymes. By studying transcriptional regulation, enzyme approaches, activity assays with in vitro purified proteins and in vivo and in vitro NO determinations, we have addressed the role of NR and Amidoxime Reducing Component (ARC) in the NO synthesis process. N\R and ARC were intimately related both at transcriptional and activity level. Thus, arc mutants showed high NIA1 (NR gene) expression and NR activity. Conversely, mutants without active NR displayed an increased ARC expression in nitrite medium. Our results with nia1 and arc mutants and with purified enzymes support that ARC catalyses the NO production from nitrite taking electrons from NR and not from Cytb5-1/Cytb5-Reductase, the component partners previously described for ARC (proposed as NOFNiR, Nitric Oxide-Forming Nitrite Reductase). This NR-ARC dual system would be able to produce NO in the presence of nitrate, condition under which NR is unable to do it.
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Affiliation(s)
- Alejandro Chamizo-Ampudia
- Department of Biochemistry and Molecular Biology, University of Córdoba, Campus de Rabanales, Campus de excelencia internacional (CeiA3), Edif. Severo Ochoa, Córdoba, 14071, Spain
| | - Emanuel Sanz-Luque
- Department of Biochemistry and Molecular Biology, University of Córdoba, Campus de Rabanales, Campus de excelencia internacional (CeiA3), Edif. Severo Ochoa, Córdoba, 14071, Spain
| | - Ángel Llamas
- Department of Biochemistry and Molecular Biology, University of Córdoba, Campus de Rabanales, Campus de excelencia internacional (CeiA3), Edif. Severo Ochoa, Córdoba, 14071, Spain
| | - Francisco Ocaña-Calahorro
- Department of Biochemistry and Molecular Biology, University of Córdoba, Campus de Rabanales, Campus de excelencia internacional (CeiA3), Edif. Severo Ochoa, Córdoba, 14071, Spain
| | - Vicente Mariscal
- Institute of Plant Biochemistry and Photosynthesis, C.S.I.C. and University of Sevilla, Américo Vespucio 49, Sevilla, 41092, Spain
| | - Alfonso Carreras
- Group of Biochemistry and Cell Signaling in Nitric Oxide. Department of Biochemistry and Molecular Biology, Campus 'Las Lagunillas', E-23071, University of Jaén, Jaén, Spain
| | - Juan B Barroso
- Group of Biochemistry and Cell Signaling in Nitric Oxide. Department of Biochemistry and Molecular Biology, Campus 'Las Lagunillas', E-23071, University of Jaén, Jaén, Spain
| | - Aurora Galván
- Department of Biochemistry and Molecular Biology, University of Córdoba, Campus de Rabanales, Campus de excelencia internacional (CeiA3), Edif. Severo Ochoa, Córdoba, 14071, Spain
| | - Emilio Fernández
- Department of Biochemistry and Molecular Biology, University of Córdoba, Campus de Rabanales, Campus de excelencia internacional (CeiA3), Edif. Severo Ochoa, Córdoba, 14071, Spain.
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18
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Beyond Tryptophan Synthase: Identification of Genes That Contribute to Chlamydia trachomatis Survival during Gamma Interferon-Induced Persistence and Reactivation. Infect Immun 2016; 84:2791-801. [PMID: 27430273 DOI: 10.1128/iai.00356-16] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 07/15/2016] [Indexed: 12/31/2022] Open
Abstract
Chlamydia trachomatis can enter a viable but nonculturable state in vitro termed persistence. A common feature of C. trachomatis persistence models is that reticulate bodies fail to divide and make few infectious progeny until the persistence-inducing stressor is removed. One model of persistence that has relevance to human disease involves tryptophan limitation mediated by the host enzyme indoleamine 2,3-dioxygenase, which converts l-tryptophan to N-formylkynurenine. Genital C. trachomatis strains can counter tryptophan limitation because they encode a tryptophan-synthesizing enzyme. Tryptophan synthase is the only enzyme that has been confirmed to play a role in interferon gamma (IFN-γ)-induced persistence, although profound changes in chlamydial physiology and gene expression occur in the presence of persistence-inducing stressors. Thus, we screened a population of mutagenized C. trachomatis strains for mutants that failed to reactivate from IFN-γ-induced persistence. Six mutants were identified, and the mutations linked to the persistence phenotype in three of these were successfully mapped. One mutant had a missense mutation in tryptophan synthase; however, this mutant behaved differently from previously described synthase null mutants. Two hypothetical genes of unknown function, ctl0225 and ctl0694, were also identified and may be involved in amino acid transport and DNA damage repair, respectively. Our results indicate that C. trachomatis utilizes functionally diverse genes to mediate survival during and reactivation from persistence in HeLa cells.
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Sanz-Luque E, Ocaña-Calahorro F, de Montaigu A, Chamizo-Ampudia A, Llamas Á, Galván A, Fernández E. THB1, a truncated hemoglobin, modulates nitric oxide levels and nitrate reductase activity. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 81:467-79. [PMID: 25494936 DOI: 10.1111/tpj.12744] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 11/21/2014] [Accepted: 12/02/2014] [Indexed: 05/18/2023]
Abstract
Hemoglobins are ubiquitous proteins that sense, store and transport oxygen, but the physiological processes in which they are implicated is currently expanding. Recent examples of previously unknown hemoglobin functions, which include scavenging of the signaling molecule nitric oxide (NO), illustrate how the implication of hemoglobins in different cell signaling processes is only starting to be unraveled. The extent and diversity of the hemoglobin protein family suggest that hemoglobins have diverged and have potentially evolved specialized functions in certain organisms. A unique model organism to study this functional diversity at the cellular level is the green alga Chlamydomonas reinhardtii because, among other reasons, it contains an unusually high number of a particular type of hemoglobins known as truncated hemoglobins (THB1-THB12). Here, we reveal a cell signaling function for a truncated hemoglobin of Chlamydomonas that affects the nitrogen assimilation pathway by simultaneously modulating NO levels and nitrate reductase (NR) activity. First, we found that THB1 and THB2 expression is modulated by the nitrogen source and depends on NIT2, a transcription factor required for nitrate assimilation genes expression. Furthermore, THB1 is highly expressed in the presence of NO and is able to convert NO into nitrate in vitro. Finally, THB1 is maintained on its active and reduced form by NR, and in vivo lower expression of THB1 results in increased NR activity. Thus, THB1 plays a dual role in NO detoxification and in the modulation of NR activity. This mechanism can partly explain how NO inhibits NR post-translationally.
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Affiliation(s)
- Emanuel Sanz-Luque
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de Córdoba, Campus de Rabanales, Campus de excelencia internacional (CeiA3), Edif. Severo Ochoa, 14071, Córdoba, Spain
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20
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The mammalian molybdenum enzymes of mARC. J Biol Inorg Chem 2014; 20:265-75. [PMID: 25425164 DOI: 10.1007/s00775-014-1216-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 11/11/2014] [Indexed: 01/14/2023]
Abstract
The "mitochondrial amidoxime reducing component" (mARC) is the most recently discovered molybdenum-containing enzyme in mammals. All mammalian genomes studied to date contain two mARC genes: MARC1 and MARC2. The proteins encoded by these genes are mARC-1 and mARC-2 and represent the simplest form of eukaryotic molybdenum enzymes, only binding the molybdenum cofactor. In the presence of NADH, mARC proteins exert N-reductive activity together with the two electron transport proteins cytochrome b5 type B and NADH cytochrome b5 reductase. This enzyme system is capable of reducing a great variety of N-hydroxylated substrates. It plays a decisive role in the activation of prodrugs containing an amidoxime structure, and in detoxification pathways, e.g., of N-hydroxylated purine and pyrimidine bases. It belongs to a group of drug metabolism enzymes, in particular as a counterpart of P450 formed N-oxygenated metabolites. Its physiological relevance, on the other hand, is largely unknown. The aim of this article is to summarize our current knowledge of these proteins with a special focus on the mammalian enzymes and their N-reductive activity.
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Tejada-Jiménez M, Schwarz G. Molybdenum and Tungsten. BINDING, TRANSPORT AND STORAGE OF METAL IONS IN BIOLOGICAL CELLS 2014. [DOI: 10.1039/9781849739979-00223] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Molybdenum (Mo) is an essential micronutrient for the majority of organisms ranging from bacteria to animals. To fulfil its biological role, it is incorporated into a pterin-based Mo-cofactor (Moco) and can be found in the active centre of more than 50 enzymes that are involved in key reactions of carbon, nitrogen and sulfur metabolism. Five of the Mo-enzymes are present in eukaryotes: nitrate reductase (NR), sulfite oxidase (SO), aldehyde oxidase (AO), xanthine oxidase (XO) and the amidoxime-reducing component (mARC). Cells acquire Mo in form of the oxyanion molybdate using specific molybdate transporters. In bacteria, molybdate transport is an extensively studied process and is mediated mainly by the ATP-binding cassette system ModABC. In contrast, in eukaryotes, molybdate transport is poorly understood since specific molybdate transporters remained unknown until recently. Two rather distantly related families of proteins, MOT1 and MOT2, are involved in eukaryotic molybdate transport. They each feature high-affinity molybdate transporters that regulate the intracellular concentration of Mo and thus control activity of Mo-enzymes. The present chapter presents an overview of the biological functions of Mo with special focus on recent data related to its uptake, binding and storage.
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Affiliation(s)
- Manuel Tejada-Jiménez
- Institute of Biochemistry, Department of Chemistry, University of Cologne Zuelpicher Str. 47 Cologne 50674 Germany
| | - Guenter Schwarz
- Institute of Biochemistry, Department of Chemistry, University of Cologne Zuelpicher Str. 47 Cologne 50674 Germany
- Center for Molecular Medicine Cologne, University of Cologne Robert-Koch Str. 21 Cologne 50931 Germany
- Cluster of Excellence in Ageing Research, CECAD Research Center Joseph-Stelzmann-Str. 26 Cologne 50931 Germany
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Abstract
Molybdenum is an essential trace element and crucial for the survival of animals. Four mammalian Mo-dependent enzymes are known, all of them harboring a pterin-based molybdenum cofactor (Moco) in their active site. In these enzymes, molybdenum catalyzes oxygen transfer reactions from or to substrates using water as oxygen donor or acceptor. Molybdenum shuttles between two oxidation states, Mo(IV) and Mo(VI). Following substrate reduction or oxidation, electrons are subsequently shuttled by either inter- or intra-molecular electron transfer chains involving prosthetic groups such as heme or iron-sulfur clusters. In all organisms studied so far, Moco is synthesized by a highly conserved multi-step biosynthetic pathway. A deficiency in the biosynthesis of Moco results in a pleitropic loss of all four human Mo-enzyme activities and in most cases in early childhood death. In this review we first introduce general aspects of molybdenum biochemistry before we focus on the functions and deficiencies of two Mo-enzymes, xanthine dehydrogenase and sulfite oxidase, caused either by deficiency of the apo-protein or a pleiotropic loss of Moco due to a genetic defect in its biosynthesis. The underlying molecular basis of Moco deficiency, possible treatment options and links to other diseases, such as neuropsychiatric disorders, will be discussed.
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Affiliation(s)
- Guenter Schwarz
- Institute of Biochemistry, Department of Chemistry, Center for Molecular Medicine, University of Cologne, Zülpicher Strasse 47, D-50674, Köln, Germany,
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Sparacino-Watkins CE, Tejero J, Sun B, Gauthier MC, Thomas J, Ragireddy V, Merchant BA, Wang J, Azarov I, Basu P, Gladwin MT. Nitrite reductase and nitric-oxide synthase activity of the mitochondrial molybdopterin enzymes mARC1 and mARC2. J Biol Chem 2014; 289:10345-10358. [PMID: 24500710 DOI: 10.1074/jbc.m114.555177] [Citation(s) in RCA: 111] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Mitochondrial amidoxime reducing component (mARC) proteins are molybdopterin-containing enzymes of unclear physiological function. Both human isoforms mARC-1 and mARC-2 are able to catalyze the reduction of nitrite when they are in the reduced form. Moreover, our results indicate that mARC can generate nitric oxide (NO) from nitrite when forming an electron transfer chain with NADH, cytochrome b5, and NADH-dependent cytochrome b5 reductase. The rate of NO formation increases almost 3-fold when pH was lowered from 7.5 to 6.5. To determine if nitrite reduction is catalyzed by molybdenum in the active site of mARC-1, we mutated the putative active site cysteine residue (Cys-273), known to coordinate molybdenum binding. NO formation was abolished by the C273A mutation in mARC-1. Supplementation of transformed Escherichia coli with tungsten facilitated the replacement of molybdenum in recombinant mARC-1 and abolished NO formation. Therefore, we conclude that human mARC-1 and mARC-2 are capable of catalyzing reduction of nitrite to NO through reaction with its molybdenum cofactor. Finally, expression of mARC-1 in HEK cells using a lentivirus vector was used to confirm cellular nitrite reduction to NO. A comparison of NO formation profiles between mARC and xanthine oxidase reveals similar Kcat and Vmax values but more sustained NO formation from mARC, possibly because it is not vulnerable to autoinhibition via molybdenum desulfuration. The reduction of nitrite by mARC in the mitochondria may represent a new signaling pathway for NADH-dependent hypoxic NO production.
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Affiliation(s)
- Courtney E Sparacino-Watkins
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15261; Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15213
| | - Jesús Tejero
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Bin Sun
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15261; Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15213
| | - Marc C Gauthier
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15261; Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15213
| | - John Thomas
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282
| | - Venkata Ragireddy
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Bonnie A Merchant
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Jun Wang
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Ivan Azarov
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Partha Basu
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282
| | - Mark T Gladwin
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15261; Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15213.
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24
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Ott G, Reichmann D, Boerger C, Cascorbi I, Bittner F, Mendel RR, Kunze T, Clement B, Havemeyer A. Functional characterization of protein variants encoded by nonsynonymous single nucleotide polymorphisms in MARC1 and MARC2 in healthy Caucasians. Drug Metab Dispos 2014; 42:718-25. [PMID: 24423752 DOI: 10.1124/dmd.113.055202] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Human molybdenum-containing enzyme mitochondrial amidoxime reducing component (mARC), cytochrome b5 type B, and NADH cytochrome b5 reductase form an N-reductive enzyme system that is capable of reducing N-hydroxylated compounds. Genetic variations are known, but their functional relevance is unclear. Our study aimed to investigate the incidence of nonsynonymous single nucleotide polymorphisms (SNPs) in the mARC genes in healthy Caucasian volunteers, to determine saturation of the protein variants with molybdenum cofactor (Moco), and to characterize the kinetic behavior of the protein variants by in vitro biotransformation studies. Genotype frequencies of six SNPs in the mARC genes (c.493A>G, c.560T>A, c.736T>A, and c.739G>C in MARC1; c.730G>A and c.735T>G in MARC2) were determined by pyrosequencing in a cohort of 340 healthy Caucasians. Protein variants were expressed in Escherichia coli. Saturation with Moco was determined by measurement of molybdenum by inductively coupled mass spectrometry. Steady state assays were performed with benzamidoxime. The six variants were of low frequency in this Caucasian population. Only one homozygous variant (c.493A; MARC1) was detected. All protein variants were able to bind Moco. Steady state assays showed statistically significant decreases of catalytic efficiency values for the mARC-2 wild type compared with the mARC-1 wild type (P < 0.05) and for two mARC-2 variants compared with the mARC-2 wild type (G244S, P < 0.05; C245W, P < 0.05). After simultaneous substitution of more than two amino acids in the mARC-1 protein, N-reductive activity was decreased 5-fold. One homozygous variant of MARC1 was detected in our sample. The encoded protein variant (A165T) showed no different kinetic parameters in the N-reduction of benzamidoxime.
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Affiliation(s)
- Gudrun Ott
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Christian-Albrechts-University of Kiel, Kiel, Germany (G.O., T.K., B.C., A.H.); Department of Plant Biology, Technical University of Braunschweig, Braunschweig, Germany (D.R., F.B., R.-R.M.); and Institute of Experimental and Clinical Pharmacology, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany (C.B., I.C.)
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25
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Bittner F. Molybdenum metabolism in plants and crosstalk to iron. FRONTIERS IN PLANT SCIENCE 2014; 5:28. [PMID: 24570679 PMCID: PMC3916724 DOI: 10.3389/fpls.2014.00028] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Accepted: 01/22/2014] [Indexed: 05/04/2023]
Abstract
In the form of molybdate the transition metal molybdenum is essential for plants as it is required by a number of enzymes that catalyze key reactions in nitrogen assimilation, purine degradation, phytohormone synthesis, and sulfite detoxification. However, molybdate itself is biologically inactive and needs to be complexed by a specific organic pterin in order to serve as a permanently bound prosthetic group, the molybdenum cofactor, for the socalled molybdo-enyzmes. While the synthesis of molybdenum cofactor has been intensively studied, only little is known about the uptake of molybdate by the roots, its transport to the shoot and its allocation and storage within the cell. Yet, recent evidence indicates that intracellular molybdate levels are tightly controlled by molybdate transporters, in particular during plant development. Moreover, a tight connection between molybdenum and iron metabolisms is presumed because (i) uptake mechanisms for molybdate and iron affect each other, (ii) most molybdo-enzymes do also require iron-containing redox groups such as iron-sulfur clusters or heme, (iii) molybdenum metabolism has recruited mechanisms typical for iron-sulfur cluster synthesis, and (iv) both molybdenum cofactor synthesis and extramitochondrial iron-sulfur proteins involve the function of a specific mitochondrial ABC-type transporter.
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Affiliation(s)
- Florian Bittner
- *Correspondence: Florian Bittner, Department of Plant Biology, Braunschweig University of Technology, Spielmannstrasse 7, 38106 Braunschweig, Germany e-mail:
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26
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Kozmin SG, Stepchenkova EI, Schaaper RM. TusA (YhhP) and IscS are required for molybdenum cofactor-dependent base-analog detoxification. Microbiologyopen 2013; 2:743-55. [PMID: 23894086 PMCID: PMC3831636 DOI: 10.1002/mbo3.108] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Revised: 05/30/2013] [Accepted: 06/07/2013] [Indexed: 12/15/2022] Open
Abstract
Lack of molybdenum cofactor (Moco) in Escherichia coli leads to hypersensitivity to the mutagenic and toxic effects of N-hydroxylated base analogs, such as 6-N-hydroxylaminopurine (HAP). This phenotype is due to the loss of two Moco-dependent activities, YcbX and YiiM, that are capable of reducing HAP to adenine. Here, we describe two novel HAP-sensitive mutants containing a defect in iscS or tusA (yhhP) gene. IscS is a major L-cysteine desulfurase involved in iron-sulfur cluster synthesis, thiamine synthesis, and tRNA thiomodification. TusA is a small sulfur-carrier protein that interacts with IscS. We show that both IscS and TusA operate within the Moco-dependent pathway. Like other Moco-deficient strains, tusA and iscS mutants are HAP sensitive and resistant to chlorate under anaerobic conditions. The base-analog sensitivity of iscS or tusA strains could be suppressed by supplying exogenous L-cysteine or sulfide or by an increase in endogenous sulfur donors (cysB constitutive mutant). The data suggest that iscS and tusA mutants have a defect in the mobilization of sulfur required for active YcbX/YiiM proteins as well as nitrate reductase, presumably due to lack of functional Moco. Overall, our data imply a novel and indispensable role of the IscS/TusA complex in the activity of several molybdoenzymes.
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Affiliation(s)
- Stanislav G Kozmin
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, 27709
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27
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Abstract
A perspective is provided of recent advances in our understanding of molybdenum-containing enzymes other than nitrogenase, a large and diverse group of enzymes that usually (but not always) catalyze oxygen atom transfer to or from a substrate, utilizing a Mo=O group as donor or acceptor. An emphasis is placed on the diversity of protein structure and reaction catalyzed by each of the three major families of these enzymes.
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Affiliation(s)
- Russ Hille
- Department of Biochemistry, University of California, 1643 Boyce Hall, Riverside, CA 92521, USA.
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28
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Characterization of Chlamydomonas 102 and 104 Mutants Reveals Intermolecular Complementation in the Molybdenum Cofactor Protein CNX1E. Protist 2013; 164:116-28. [DOI: 10.1016/j.protis.2012.04.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Revised: 04/10/2012] [Accepted: 04/10/2012] [Indexed: 02/04/2023]
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29
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Tejada-Jiménez M, Chamizo-Ampudia A, Galván A, Fernández E, Llamas Á. Molybdenum metabolism in plants. Metallomics 2013; 5:1191-203. [DOI: 10.1039/c3mt00078h] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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30
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Krompholz N, Krischkowski C, Reichmann D, Garbe-Schönberg D, Mendel RR, Bittner F, Clement B, Havemeyer A. The mitochondrial Amidoxime Reducing Component (mARC) is involved in detoxification of N-hydroxylated base analogues. Chem Res Toxicol 2012; 25:2443-50. [PMID: 22924387 DOI: 10.1021/tx300298m] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The "mitochondrial Amidoxime Reducing Component" (mARC) is the newly discovered fourth molybdenum enzyme in mammals. All hitherto analyzed mammals express two mARC proteins, referred to as mARC1 and mARC2. Together with their electron transport proteins cytochrome b(5) and NADH cytochrome b(5) reductase, they form a three-component enzyme system and catalyze the reduction of N-hydroxylated prodrugs. Here, we demonstrate the reductive detoxification of toxic and mutagenic N-hydroxylated nucleobases and their corresponding nucleosides by the mammalian mARC-containing enzyme system. The N-reductive activity was found in all tested tissues with the highest detectable conversion rates in liver, kidney, thyroid, and pancreas. According to the presumed localization, the N-reductive activity is most pronounced in enriched mitochondrial fractions. In vitro assays with the respective recombinant three-component enzyme system show that both mARC isoforms are able to reduce N-hydroxylated base analogues, with mARC1 representing the more efficient isoform. On the basis of the high specific activities with N-hydroxylated base analogues relative to other N-hydroxylated substrates, our data suggest that mARC proteins might be involved in protecting cellular DNA from misincorporation of toxic N-hydroxylated base analogues during replication by converting them to the correct purine or pyrimidine bases, respectively.
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Affiliation(s)
- Nina Krompholz
- Pharmaceutical Institute, Christian-Albrechts-University of Kiel, Germany 24118
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31
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Mendel RR, Kruse T. Cell biology of molybdenum in plants and humans. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:1568-79. [PMID: 22370186 DOI: 10.1016/j.bbamcr.2012.02.007] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Revised: 02/08/2012] [Accepted: 02/10/2012] [Indexed: 12/29/2022]
Abstract
The transition element molybdenum (Mo) needs to be complexed by a special cofactor in order to gain catalytic activity. With the exception of bacterial Mo-nitrogenase, where Mo is a constituent of the FeMo-cofactor, Mo is bound to a pterin, thus forming the molybdenum cofactor Moco, which in different variants is the active compound at the catalytic site of all other Mo-containing enzymes. In eukaryotes, the most prominent Mo-enzymes are nitrate reductase, sulfite oxidase, xanthine dehydrogenase, aldehyde oxidase, and the mitochondrial amidoxime reductase. The biosynthesis of Moco involves the complex interaction of six proteins and is a process of four steps, which also requires iron, ATP and copper. After its synthesis, Moco is distributed to the apoproteins of Mo-enzymes by Moco-carrier/binding proteins. A deficiency in the biosynthesis of Moco has lethal consequences for the respective organisms. In humans, Moco deficiency is a severe inherited inborn error in metabolism resulting in severe neurodegeneration in newborns and causing early childhood death. This article is part of a Special Issue entitled: Cell Biology of Metals.
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Affiliation(s)
- Ralf R Mendel
- Institute of Plant Biology, Braunschweig University of Technology, 1 Humboldt Street, 38106 Braunschweig, Germany.
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