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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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2
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Mendel RR. The History of the Molybdenum Cofactor—A Personal View. Molecules 2022; 27:molecules27154934. [PMID: 35956883 PMCID: PMC9370521 DOI: 10.3390/molecules27154934] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 07/26/2022] [Accepted: 07/28/2022] [Indexed: 11/16/2022] Open
Abstract
The transition element molybdenum (Mo) is an essential micronutrient for plants, animals, and microorganisms, where it forms part of the active center of Mo enzymes. To gain biological activity in the cell, Mo has to be complexed by a pterin scaffold to form the molybdenum cofactor (Moco). Mo enzymes and Moco are found in all kingdoms of life, where they perform vital transformations in the metabolism of nitrogen, sulfur, and carbon compounds. In this review, I recall the history of Moco in a personal view, starting with the genetics of Moco in the 1960s and 1970s, followed by Moco biochemistry and the description of its chemical structure in the 1980s. When I review the elucidation of Moco biosynthesis in the 1990s and the early 2000s, I do it mainly for eukaryotes, as I worked with plants, human cells, and filamentous fungi. Finally, I briefly touch upon human Moco deficiency and whether there is life without Moco.
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Affiliation(s)
- Ralf R Mendel
- Institute of Plant Biology, Technical University Braunschweig, Humboldtstrasse 1, 38106 Braunschweig, Germany
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3
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Warnhoff K, Hercher TW, Mendel RR, Ruvkun G. Protein-bound molybdenum cofactor is bioavailable and rescues molybdenum cofactor-deficient C. elegans. Genes Dev 2021; 35:212-217. [PMID: 33446569 PMCID: PMC7849362 DOI: 10.1101/gad.345579.120] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 12/01/2020] [Indexed: 01/10/2023]
Abstract
In this paper, Warnoff et al. investigated the mechanism by which C. elegans stably acquires molybdenum cofactor (Moco), which is essential in animals and causes lethal neurological and developmental defects in humans with mutations in genes that encode Moco biosynthetic enzymes. The authors show that protein-bound Moco is the stable, bioavailable species of Moco taken up by C. elegans from its diet and is an effective dietary supplement in a C. elegans model of Moco deficiency, and that these Moco:protein complexes are very stable, suggesting they may provide a strategy for the production and delivery of therapeutically active Moco to treat human Moco deficiency. The molybdenum cofactor (Moco) is a 520-Da prosthetic group that is synthesized in all domains of life. In animals, four oxidases (among them sulfite oxidase) use Moco as a prosthetic group. Moco is essential in animals; humans with mutations in genes that encode Moco biosynthetic enzymes display lethal neurological and developmental defects. Moco supplementation seems a logical therapy; however, the instability of Moco has precluded biochemical and cell biological studies of Moco transport and bioavailability. The nematode Caenorhabditis elegans can take up Moco from its bacterial diet and transport it to cells and tissues that express Moco-requiring enzymes, suggesting a system for Moco uptake and distribution. Here we show that protein-bound Moco is the stable, bioavailable species of Moco taken up by C. elegans from its diet and is an effective dietary supplement, rescuing a C. elegans model of Moco deficiency. We demonstrate that diverse Moco:protein complexes are stable and bioavailable, suggesting a new strategy for the production and delivery of therapeutically active Moco to treat human Moco deficiency.
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Affiliation(s)
- Kurt Warnhoff
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114.,Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115
| | - Thomas W Hercher
- Braunschweig University of Technology, 38106 Braunschweig, Germany
| | - Ralf R Mendel
- Braunschweig University of Technology, 38106 Braunschweig, Germany
| | - Gary Ruvkun
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114.,Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115
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Identification and characterisation of the Volvox carteri Moco carrier protein. Biosci Rep 2020; 40:226728. [PMID: 33084886 PMCID: PMC7687042 DOI: 10.1042/bsr20202351] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 10/08/2020] [Accepted: 10/13/2020] [Indexed: 11/23/2022] Open
Abstract
The molybdenum cofactor (Moco) is a redox active prosthetic group found in the active site of Moco-dependent enzymes (Mo-enzymes). As Moco and its intermediates are highly sensitive towards oxidative damage, these are believed to be permanently protein bound during synthesis and upon maturation. As a major component of the plant Moco transfer and storage system, proteins have been identified that are capable of Moco binding and release but do not possess Moco-dependent enzymatic activities. The first protein found to possess these properties was the Moco carrier protein (MCP) from the green alga Chlamydomonas reinhardtii. Here, we describe the identification and biochemical characterisation of the Volvox carteri (V. carteri) MCP and, for the first time, employ a comparative analysis to elucidate the principles behind MCP Moco binding. Doing so identified a sequence region of low homology amongst the existing MCPs, which we showed to be essential for Moco binding to V. carteri MCP.
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5
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Mayr SJ, Mendel RR, Schwarz G. Molybdenum cofactor biology, evolution and deficiency. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1868:118883. [PMID: 33017596 DOI: 10.1016/j.bbamcr.2020.118883] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 09/21/2020] [Accepted: 09/24/2020] [Indexed: 12/14/2022]
Abstract
The molybdenum cofactor (Moco) represents an ancient metal‑sulfur cofactor, which participates as catalyst in carbon, nitrogen and sulfur cycles, both on individual and global scale. Given the diversity of biological processes dependent on Moco and their evolutionary age, Moco is traced back to the last universal common ancestor (LUCA), while Moco biosynthetic genes underwent significant changes through evolution and acquired additional functions. In this review, focused on eukaryotic Moco biology, we elucidate the benefits of gene fusions on Moco biosynthesis and beyond. While originally the gene fusions were driven by biosynthetic advantages such as coordinated expression of functionally related proteins and product/substrate channeling, they also served as origin for the development of novel functions. Today, Moco biosynthetic genes are involved in a multitude of cellular processes and loss of the according gene products result in severe disorders, both related to Moco biosynthesis and secondary enzyme functions.
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Affiliation(s)
- Simon J Mayr
- Institute of Biochemistry, Department of Chemistry, Center for Molecular Medicine, University of Cologne, Zuelpicher Str. 47, 50674 Koeln, Germany
| | - Ralf-R Mendel
- Institute of Plant Biology, Braunschweig University of Technology, Humboldtstr. 1, 38106 Braunschweig, Germany
| | - Guenter Schwarz
- Institute of Biochemistry, Department of Chemistry, Center for Molecular Medicine, University of Cologne, Zuelpicher Str. 47, 50674 Koeln, Germany.
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Krausze J, Hercher TW, Archna A, Kruse T. The structure of the Moco carrier protein from Rippkaea orientalis. Acta Crystallogr F Struct Biol Commun 2020; 76:453-463. [PMID: 32880594 PMCID: PMC7470044 DOI: 10.1107/s2053230x20011073] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 08/11/2020] [Indexed: 12/28/2022] Open
Abstract
The molybdenum cofactor (Moco) is the prosthetic group of all molybdenum-dependent enzymes except for nitrogenase. The multistep biosynthesis pathway of Moco and its function in molybdenum-dependent enzymes are already well understood. The mechanisms of Moco transfer, storage and insertion, on the other hand, are not. In the cell, Moco is usually not found in its free form and remains bound to proteins because of its sensitivity to oxidation. The green alga Chlamydomonas reinhardtii harbors a Moco carrier protein (MCP) that binds and protects Moco but is devoid of enzymatic function. It has been speculated that this MCP acts as a means of Moco storage and transport. Here, the search for potential MCPs has been extended to the prokaryotes, and many MCPs were found in cyanobacteria. A putative MCP from Rippkaea orientalis (RoMCP) was selected for recombinant production, crystallization and structure determination. RoMCP has a Rossmann-fold topology that is characteristic of nucleotide-binding proteins and a homotetrameric quaternary structure similar to that of the MCP from C. reinhardtii. In each protomer, a positively charged crevice was identified that accommodates up to three chloride ions, hinting at a potential Moco-binding site. Computational docking experiments supported this notion and gave an impression of the RoMCP-Moco complex.
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Affiliation(s)
- Joern Krausze
- Institute of Plant Biology, TU Braunschweig, 38106 Braunschweig, Germany
| | - Thomas W. Hercher
- Institute of Plant Biology, TU Braunschweig, 38106 Braunschweig, Germany
| | - Archna Archna
- Institute of Plant Biology, TU Braunschweig, 38106 Braunschweig, Germany
| | - Tobias Kruse
- Institute of Plant Biology, TU Braunschweig, 38106 Braunschweig, Germany
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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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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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9
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Seo H, Kim KJ. Structural basis for a novel type of cytokinin-activating protein. Sci Rep 2017; 7:45985. [PMID: 28374778 PMCID: PMC5379747 DOI: 10.1038/srep45985] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 03/07/2017] [Indexed: 12/20/2022] Open
Abstract
The Lonely Guy (LOG) protein has been identified as a crucial enzyme involved in the production of cytokinins, which are important phytohormones, in plants and plant-interacting organisms. However, C. glutamicum has an isoform (Cg1261) of LOG that contains an extended N-terminal region compared to those of known LOGs, and this type of isoforms are also found in a variety of organisms. Nevertheless, these proteins are considered as lysine decarboxylases, without their functional characterization. To investigate the function of Cg1261, we determined its crystal structure at a resolution of 1.95 Å. Unlike known dimeric LOGs, Cg1261 was found to form a hexamer. The overall shape of the hexamer resembles a trillium flower, in which a twisted dimer constitutes each petal. The dimeric petal is well superposed with known LOG dimers, and its active site conformation is similar to those of LOG dimers, suggesting that the hexameric LOG-like protein also acts as a LOG. Biochemical and in vivo cytokinin production studies on Cg1261 confirms that Cg1261 functions as a cytokinin-activating protein. Phylogenetic tree analysis using 123 LOG-like proteins suggest that the LOG-like proteins can be categorized to the dimeric type-I LOG and the hexameric type-II LOG.
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Affiliation(s)
- Hogyun Seo
- School of Life Sciences, KNU Creative BioResearch Group, Kyungpook National University, Daegu 702-701, Republic of Korea
| | - Kyung-Jin Kim
- School of Life Sciences, KNU Creative BioResearch Group, Kyungpook National University, Daegu 702-701, Republic of Korea
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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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Kaufholdt D, Baillie CK, Meyer MH, Schwich OD, Timmerer UL, Tobias L, van Thiel D, Hänsch R, Mendel RR. Identification of a protein-protein interaction network downstream of molybdenum cofactor biosynthesis in Arabidopsis thaliana. JOURNAL OF PLANT PHYSIOLOGY 2016; 207:42-50. [PMID: 27792900 DOI: 10.1016/j.jplph.2016.10.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 10/06/2016] [Accepted: 10/07/2016] [Indexed: 05/24/2023]
Abstract
The molybdenum cofactor (Moco) is ubiquitously present in all kingdoms of life and vitally important for survival. Among animals, loss of the Moco-containing enzyme (Mo-enzyme) sulphite oxidase is lethal, while for plants the loss of nitrate reductase prohibits nitrogen assimilation. Moco is highly oxygen-sensitive, which obviates a freely diffusible pool and necessitates protein-mediated distribution. During the highly conserved Moco biosynthesis pathway, intermediates are channelled through a multi-protein complex facilitating protected transport. However, the mechanism by which Moco is subsequently transferred to apo-enzymes is still unclear. Moco user enzymes can be divided into two families: the sulphite oxidase (SO) and the xanthine oxidoreductase (XOR) family. The latter requires a final sulphurisation of Moco catalysed via ABA3. To examine Moco transfer towards apo-Mo-enzymes, two different and independent protein-protein interaction assays were performed in vivo: bimolecular fluorescence complementation and split luciferase. The results revealed a direct contact between Moco producer molybdenum insertase CNX1, which represents the last biosynthesis step, and members of the SO family. However, no protein contact was observed between Moco producer CNX1 and apo-enzymes of the XOR family or between CNX1 and the Moco sulphurase ABA3. Instead, the Moco-binding protein MOBP2 was identified as a mediator between CNX1 and ABA3. This interaction was followed by contact between ABA3 and enzymes of the XOR family. These results allow to describe an interaction matrix of proteins beyond Moco biosynthesis and to demonstrate the complexity of transferring a prosthetic group after biosynthesis.
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Affiliation(s)
- David Kaufholdt
- Department of Plant Biology, Technical University of Braunschweig, Humboldtstrasse 1, 38106 Braunschweig, Germany.
| | - Christin-Kirsty Baillie
- Department of Plant Biology, Technical University of Braunschweig, Humboldtstrasse 1, 38106 Braunschweig, Germany.
| | - Martin H Meyer
- Department of Plant Biology, Technical University of Braunschweig, Humboldtstrasse 1, 38106 Braunschweig, Germany.
| | - Oliver D Schwich
- Department of Plant Biology, Technical University of Braunschweig, Humboldtstrasse 1, 38106 Braunschweig, Germany.
| | - Ulrike L Timmerer
- Department of Plant Biology, Technical University of Braunschweig, Humboldtstrasse 1, 38106 Braunschweig, Germany.
| | - Lydia Tobias
- Department of Plant Biology, Technical University of Braunschweig, Humboldtstrasse 1, 38106 Braunschweig, Germany.
| | - Daniela van Thiel
- Department of Plant Biology, Technical University of Braunschweig, Humboldtstrasse 1, 38106 Braunschweig, Germany.
| | - Robert Hänsch
- Department of Plant Biology, Technical University of Braunschweig, Humboldtstrasse 1, 38106 Braunschweig, Germany.
| | - Ralf R Mendel
- Department of Plant Biology, Technical University of Braunschweig, Humboldtstrasse 1, 38106 Braunschweig, Germany.
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12
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Kaufholdt D, Baillie CK, Bikker R, Burkart V, Dudek CA, von Pein L, Rothkegel M, Mendel RR, Hänsch R. The molybdenum cofactor biosynthesis complex interacts with actin filaments via molybdenum insertase Cnx1 as anchor protein in Arabidopsis thaliana. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2016; 244:8-18. [PMID: 26810449 DOI: 10.1016/j.plantsci.2015.12.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 12/16/2015] [Accepted: 12/24/2015] [Indexed: 05/24/2023]
Abstract
The pterin based molybdenum cofactor (Moco) plays an essential role in almost all organisms. Its biosynthesis is catalysed by six enzymes in a conserved four step reaction pathway. The last three steps are located in the cytoplasm, where a multimeric protein complex is formed to protect the intermediates from degradation. Bimolecular fluorescence complementation was used to test for cytoskeleton association of the Moco biosynthesis enzymes with actin filaments and microtubules using known cytoskeleton associated proteins, thus permitting non-invasive in vivo studies. Coding sequences of binding proteins were cloned via the GATEWAY system. No Moco biosynthesis enzyme showed any interaction with microtubules. However, alone the two domain protein Cnx1 exhibited interaction with actin filaments mediated by both domains with the Cnx1G domain displaying a stronger interaction. Cnx6 showed actin association only if unlabelled Cnx1 was co-expressed in comparable amounts. So Cnx1 is likely to be the anchor protein for the whole biosynthesis complex on actin filaments. A stabilization of the whole Moco biosynthesis complex on the cytoskeleton might be crucial. In addition a micro-compartmentation might either allow a localisation near the mitochondrial ATM3 exporter providing the first Moco intermediate or near one of the three molybdate transporters enabling efficient molybdate incorporation.
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Affiliation(s)
- David Kaufholdt
- Institut für Pflanzenbiologie, Humboldtstrasse 1, Technische Universität Braunschweig, D-38106 Braunschweig, Germany.
| | - Christin-Kirsty Baillie
- Institut für Pflanzenbiologie, Humboldtstrasse 1, Technische Universität Braunschweig, D-38106 Braunschweig, Germany.
| | - Rolf Bikker
- Institut für Pflanzenbiologie, Humboldtstrasse 1, Technische Universität Braunschweig, D-38106 Braunschweig, Germany.
| | - Valentin Burkart
- Institut für Pflanzenbiologie, Humboldtstrasse 1, Technische Universität Braunschweig, D-38106 Braunschweig, Germany.
| | - Christian-Alexander Dudek
- Institut für Pflanzenbiologie, Humboldtstrasse 1, Technische Universität Braunschweig, D-38106 Braunschweig, Germany.
| | - Linn von Pein
- Institut für Pflanzenbiologie, Humboldtstrasse 1, Technische Universität Braunschweig, D-38106 Braunschweig, Germany.
| | - Martin Rothkegel
- Institut für Zoologie, Spielmannstrasse 7, Technische Universität Braunschweig, D-38106 Braunschweig, Germany.
| | - Ralf R Mendel
- Institut für Pflanzenbiologie, Humboldtstrasse 1, Technische Universität Braunschweig, D-38106 Braunschweig, Germany.
| | - Robert Hänsch
- Institut für Pflanzenbiologie, Humboldtstrasse 1, Technische Universität Braunschweig, D-38106 Braunschweig, Germany.
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Abstract
The transition element molybdenum (Mo) is of primordial importance for biological systems as it is required by enzymes catalyzing key reactions in global carbon, sulfur, and nitrogen metabolism. In order to gain biological activity, Mo has to be complexed by a special cofactor. With the exception of bacterial nitrogenase, all Mo-dependent enzymes contain a unique pyranopterin-based cofactor coordinating a Mo atom at their catalytic site. Various types of reactions are catalyzed by Mo enzymes in prokaryotes, including oxygen atom transfer, sulfur or proton transfer, hydroxylation, or even nonredox ones. Mo enzymes are widespread in prokaryotes, and many of them were likely present in LUCA. To date, more than 50-mostly bacterial-Mo enzymes are described in nature. In a few eubacteria and in many archaea, Mo is replaced by tungsten bound to the same unique pyranopterin. How Moco is synthesized in bacteria is reviewed as well as the way until its insertion into apo-Mo-enzymes.
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Abstract
The transition element molybdenum (Mo) is of primordial importance for biological systems, because it is required by enzymes catalyzing key reactions in the global carbon, sulfur, and nitrogen metabolism. To gain biological activity, Mo has to be complexed by a special cofactor. With the exception of bacterial nitrogenase, all Mo-dependent enzymes contain a unique pyranopterin-based cofactor coordinating a Mo atom at their catalytic site. Various types of reactions are catalyzed by Mo-enzymes in prokaryotes including oxygen atom transfer, sulfur or proton transfer, hydroxylation, or even nonredox reactions. Mo-enzymes are widespread in prokaryotes and many of them were likely present in the Last Universal Common Ancestor. To date, more than 50--mostly bacterial--Mo-enzymes are described in nature. In a few eubacteria and in many archaea, Mo is replaced by tungsten bound to the same unique pyranopterin. How Mo-cofactor is synthesized in bacteria is reviewed as well as the way until its insertion into apo-Mo-enzymes.
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Mendel RR, Leimkühler S. The biosynthesis of the molybdenum cofactors. J Biol Inorg Chem 2014; 20:337-47. [PMID: 24980677 DOI: 10.1007/s00775-014-1173-y] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 06/09/2014] [Indexed: 12/11/2022]
Abstract
The biosynthesis of the molybdenum cofactors (Moco) is an ancient, ubiquitous, and highly conserved pathway leading to the biochemical activation of molybdenum. Moco is the essential component of a group of redox enzymes, which are diverse in terms of their phylogenetic distribution and their architectures, both at the overall level and in their catalytic geometry. A wide variety of transformations are catalyzed by these enzymes at carbon, sulfur and nitrogen atoms, which include the transfer of an oxo group or two electrons to or from the substrate. More than 50 molybdoenzymes were identified to date. In all molybdoenzymes except nitrogenase, molybdenum is coordinated to a dithiolene group on the 6-alkyl side chain of a pterin called molybdopterin (MPT). The biosynthesis of Moco can be divided into three general steps, with a fourth one present only in bacteria and archaea: (1) formation of the cyclic pyranopterin monophosphate, (2) formation of MPT, (3) insertion of molybdenum into molybdopterin to form Moco, and (4) additional modification of Moco in bacteria with the attachment of a nucleotide to the phosphate group of MPT, forming the dinucleotide variant of Moco. This review will focus on the biosynthesis of Moco in bacteria, humans and plants.
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Affiliation(s)
- Ralf R Mendel
- Institute of Plant Biology, Braunschweig University of Technology, Humboldtstr. 1, 38106, Braunschweig, Germany,
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16
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Affiliation(s)
- Russ Hille
- Department of Biochemistry, University of California, Riverside, Riverside, California 92521, United States
| | - James Hall
- Department of Biochemistry, University of California, Riverside, Riverside, California 92521, United States
| | - Partha Basu
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282, United States
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17
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Abstract
The transition element molybdenum needs to be complexed by a special cofactor to gain catalytic activity. Molybdenum is bound to a unique pterin, thus forming the molybdenum cofactor (Moco), which, in different variants, is the active compound at the catalytic site of all molybdenum-containing enzymes in nature, except bacterial molybdenum nitrogenase. The biosynthesis of Moco involves the complex interaction of six proteins and is a process of four steps, which also require iron, ATP, and copper. After its synthesis, Moco is distributed, involving Moco-binding proteins. A deficiency in the biosynthesis of Moco has lethal consequences for the respective organisms.
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Affiliation(s)
- Ralf R Mendel
- Department of Plant Biology, Braunschweig University of Technology, 38106 Braunschweig, Germany.
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18
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19
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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: 106] [Impact Index Per Article: 8.8] [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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20
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Llamas A, Tejada-Jiménez M, Fernández E, Galván A. Molybdenum metabolism in the alga Chlamydomonas stands at the crossroad of those in Arabidopsis and humans. Metallomics 2011; 3:578-90. [PMID: 21623427 DOI: 10.1039/c1mt00032b] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Molybdenum (Mo) is a very scarce element whose function is fundamental in living beings within the active site of Mo-oxidoreductases, playing key roles in the metabolism of N, S, purines, hormone biosynthesis, transformation of drugs and xenobiotics, etc. In eukaryotes, each step from Mo acquisition until its incorporation into a biologically active molybdenum cofactor (Moco) together with the assembly of this Moco in Mo-enzymes is almost understood. The deficiency in function of a particular molybdoenzyme can be critical for the survival of the organism dependent on the pathway involved. However, incapacity in forming a functional Moco has a pleiotropic effect in the different processes involving this cofactor. A detailed overview of Mo metabolism: (a) specific transporters for molybdate, (b) the universal biosynthesis pathway for Moco from GTP, (c) Moco-carrier and Moco-binding proteins for Moco transfer and (d) Mo-enzymes, is analyzed in light of recent findings and three systems are compared, the unicellular microalga Chlamydomonas, the plant Arabidopsis and humans.
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Affiliation(s)
- Angel Llamas
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de Córdoba, Campus de Rabanales, Edif. Severo Ochoa, 14071 Córdoba, Spain.
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21
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22
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Magalon A, Fedor JG, Walburger A, Weiner JH. Molybdenum enzymes in bacteria and their maturation. Coord Chem Rev 2011. [DOI: 10.1016/j.ccr.2010.12.031] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Kruse T, Gehl C, Geisler M, Lehrke M, Ringel P, Hallier S, Hänsch R, Mendel RR. Identification and biochemical characterization of molybdenum cofactor-binding proteins from Arabidopsis thaliana. J Biol Chem 2009; 285:6623-35. [PMID: 20040598 DOI: 10.1074/jbc.m109.060640] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The molybdenum cofactor (Moco) forms part of the catalytic center in all eukaryotic molybdenum enzymes and is synthesized in a highly conserved pathway. Among eukaryotes, very little is known about the processes taking place subsequent to Moco biosynthesis, i.e. Moco transfer, allocation, and insertion into molybdenum enzymes. In the model plant Arabidopsis thaliana, we identified a novel protein family consisting of nine members that after recombinant expression are able to bind Moco with K(D) values in the low micromolar range and are therefore named Moco-binding proteins (MoBP). For two of the nine proteins atomic structures are available in the Protein Data Bank. Surprisingly, both crystal structures lack electron density for the C terminus, which may indicate a high flexibility of this part of the protein. C-terminal truncated MoBPs showed significantly decreased Moco binding stoichiometries. Experiments where the MoBP C termini were exchanged among MoBPs converted a weak Moco-binding MoBP into a strong binding MoBP, thus indicating that the MoBP C terminus, which is encoded by a separate exon, is involved in Moco binding. MoBPs were able to enhance Moco transfer to apo-nitrate reductase in the Moco-free Neurospora crassa mutant nit-1. Furthermore, we show that the MoBPs are localized in the cytosol and undergo protein-protein contact with both the Moco donor protein Cnx1 and the Moco acceptor protein nitrate reductase under in vivo conditions, thus indicating for the MoBPs a function in Arabidopsis cellular Moco distribution.
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Affiliation(s)
- Tobias Kruse
- Department of Plant Biology, Braunschweig University of Technology, 38106 Braunschweig, Germany
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25
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Tejada-Jiménez M, Galván A, Fernández E, Llamas A. Homeostasis of the micronutrients Ni, Mo and Cl with specific biochemical functions. CURRENT OPINION IN PLANT BIOLOGY 2009; 12:358-363. [PMID: 19487155 DOI: 10.1016/j.pbi.2009.04.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2008] [Revised: 04/27/2009] [Accepted: 04/27/2009] [Indexed: 05/27/2023]
Abstract
Homeostasis of three elements nickel, molybdenum and chloride is analysed. These micronutrients, at amounts varying in orders of magnitude, fulfil important cell functions. In general terms, cells use similar strategies to ensure that the elements are within physiological ranges avoiding high toxic concentrations. These strategies correspond to specific carriers, channels and pumps, intermediate steps (chelating/sequestration/binding/metabolic conversion/storage), final steps related to specific enzyme functionality and putative sensing proteins. Single cell homeostasis, coordinated with an efficient redistribution by xylem loading, ensures in turn homeostasis at the whole plant level. Recent advances are based on the molecular identification of some key components.
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Affiliation(s)
- Manuel Tejada-Jiménez
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de Córdoba, Campus de Rabanales, Córdoba, Spain
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Abstract
Cells require metal ions as cofactors for the assembly of metalloproteins. Principally one has to distinguish between metal ions that are directly incorporated into their cognate sites on proteins and those metal ions that have to become part of prosthetic groups, cofactors or complexes prior to insertion of theses moieties into target proteins. Molybdenum is only active as part of the molybdenum cofactor, iron can be part of diverse Fe-S clusters or of the heme group, while copper ions are directly delivered to their targets. We will focus in greater detail on molybdenum metabolism because molybdenum metabolism is a good example for demonstrating the role and the network of metals in metabolism: each of the three steps in the pathway of molybdenum cofactor formation depends on a different metal (iron, copper, molybdenum) and also the enzymes finally harbouring the molybdenum cofactor need additional metal-containing groups to function (iron sulfur-clusters, heme-iron).
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Affiliation(s)
- Ralf R Mendel
- Department of Plant Biology, Technical University of Braunschweig, 38106, Braunschweig, Germany.
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28
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Fischer K, Llamas A, Tejada-Jimenez M, Schrader N, Kuper J, Ataya FS, Galvan A, Mendel RR, Fernandez E, Schwarz G. Function and structure of the molybdenum cofactor carrier protein from Chlamydomonas reinhardtii. J Biol Chem 2006; 281:30186-94. [PMID: 16873364 DOI: 10.1074/jbc.m603919200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The molybdenum cofactor (Moco) forms the catalytic site in all eukaryotic molybdenum enzymes and is synthesized by a multistep biosynthetic pathway. The mechanism of transfer, storage, and insertion of Moco into the appropriate apo-enzyme is poorly understood. In Chlamydomonas reinhardtii, a Moco carrier protein (MCP) has been identified and characterized recently. Here we show biochemical evidence that MCP binds Moco as well as the tungstate-substituted form of the cofactor (Wco) with high affinity, whereas molybdopterin, the ultimate cofactor precursor, is not bound. This binding selectivity points to a specific metal-mediated interaction with MCP, which protects Moco and Wco from oxidation with t((1/2)) of 24 and 96 h, respectively. UV-visible spectroscopy showed defined absorption bands at 393, 470, and 570 nm pointing to ene-diothiolate and protein side-chain charge transfer bonds with molybdenum. We have determined the crystal structure of MCP at 1.6 Angstrom resolution using seleno-methionated and native protein. The monomer constitutes a Rossmann fold with two homodimers forming a symmetrical tetramer in solution. Based on conserved surface residues, charge distribution, shape, in silico docking studies, structural comparisons, and identification of an anionbinding site, a prominent surface depression was proposed as a Moco-binding site, which was confirmed by structure-guided mutagenesis coupled to substrate binding studies.
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Affiliation(s)
- Katrin Fischer
- Institute of Plant Biology, Technical University Braunschweig, 38106 Braunschweig, Germany
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29
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Mendel RR, Bittner F. Cell biology of molybdenum. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1763:621-35. [PMID: 16784786 DOI: 10.1016/j.bbamcr.2006.03.013] [Citation(s) in RCA: 176] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2005] [Revised: 03/13/2006] [Accepted: 03/18/2006] [Indexed: 11/17/2022]
Abstract
The transition element molybdenum (Mo) is of essential importance for (nearly) all biological systems as it is required by enzymes catalyzing diverse key reactions in the global carbon, sulfur and nitrogen metabolism. The metal itself is biologically inactive unless it is complexed by a special cofactor. With the exception of bacterial nitrogenase, where Mo is a constituent of the FeMo-cofactor, Mo is bound to a pterin, thus forming the molybdenum cofactor (Moco) which is the active compound at the catalytic site of all other Mo-enzymes. In eukaryotes, the most prominent Mo-enzymes are (1) sulfite oxidase, which catalyzes the final step in the degradation of sulfur-containing amino acids and is involved in detoxifying excess sulfite, (2) xanthine dehydrogenase, which is involved in purine catabolism and reactive oxygen production, (3) aldehyde oxidase, which oxidizes a variety of aldehydes and is essential for the biosynthesis of the phytohormone abscisic acid, and in autotrophic organisms also (4) nitrate reductase, which catalyzes the key step in inorganic nitrogen assimilation. All Mo-enzymes, except plant sulfite oxidase, need at least one more redox active center, many of them involving iron in electron transfer. The biosynthesis of Moco involves the complex interaction of six proteins and is a process of four steps, which also includes iron as well as copper in an indispensable way. Moco as released after synthesis is likely to be distributed to the apoproteins of Mo-enzymes by putative Moco-carrier proteins. Xanthine dehydrogenase and aldehyde oxidase, but not sulfite oxidase and nitrate reductase, require the post-translational sulfuration of their Mo-site for becoming active. This final maturation step is catalyzed by a Moco-sulfurase enzyme, which mobilizes sulfur from l-cysteine in a pyridoxal phosphate-dependent manner as typical for cysteine desulfurases.
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Affiliation(s)
- Ralf R Mendel
- Department of Plant Biology, Technical University of Braunschweig, Humboldtstrasse 1, 38106 Braunschweig, Germany.
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30
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Affiliation(s)
- Russ Hille
- Department of Molecular and Cellular Biochemistry, The Ohio State University, 333 Hamilton Hall, 1645 Neil Avenue, Columbus, OH 43210‐1218, USA
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31
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Llamas A, Otte T, Multhaup G, Mendel RR, Schwarz G. The Mechanism of nucleotide-assisted molybdenum insertion into molybdopterin. A novel route toward metal cofactor assembly. J Biol Chem 2006; 281:18343-50. [PMID: 16636046 DOI: 10.1074/jbc.m601415200] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The molybdenum cofactor (Moco) is synthesized by an ancient and conserved biosynthetic pathway. In plants, the two-domain protein Cnx1 catalyzes the insertion of molybdenum into molybdopterin (MPT), a metal-free phosphorylated pyranopterin carrying an ene-dithiolate. Recently, we identified a novel biosynthetic intermediate, adenylated molybdopterin (MPT-AMP), which is synthesized by the C-terminal G domain of Cnx1. Here, we show that MPT-AMP and molybdate bind in an equimolar and cooperative way to the other N-terminal E domain (Cnx1E). Tungstate and sulfate compete for molybdate, which demonstrates the presence of an anion-binding site for molybdate. Cnx1E catalyzes the Zn(2+)-/Mg(2+)-dependent hydrolysis of MPT-AMP but only when molybdate is bound as co-substrate. MPT-AMP hydrolysis resulted in stoichiometric release of Moco that was quantitatively incorporated into plant apo-sulfite oxidase. Upon Moco formation AMP is release as second product of the reaction. When comparing MPT-AMP hydrolysis with the formation of Moco and AMP a 1.5-fold difference in reaction rates were observed. Together with the strict dependence of the reaction on molybdate the formation of adenylated molybdate as reaction intermediate in the nucleotide-assisted metal transfer reaction to molybdopterin is proposed.
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Affiliation(s)
- Angel Llamas
- Institute of Plant Biology, Technical University Braunschweig, 38106 Braunschweig, Germany
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32
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Abstract
The molybdenum cofactor (Moco) forms the active site of all eukaryotic molybdenum (Mo) enzymes. Moco consists of molybdenum covalently bound to two sulfur atoms of a unique tricyclic pterin moiety referred to as molybdopterin. Moco is synthesized from GTP by an ancient and conserved biosynthetic pathway that can be divided into four steps involving the biosynthetic intermediates cyclic pyranopterin monophosphate, molybdopterin, and adenylated molybdopterin. In a fifth step, sulfuration or bond formation between Mo and a protein cysteine result in two different catalytic Mo centers. There are four Mo enzymes in plants: (1) nitrate reductase catalyzes the first and rate-limiting step in nitrate assimilation and is structurally similar to the recently identified, (2) peroxisomal sulfite oxidase that detoxifies excessive sulfite. (3) Aldehyde oxidase catalyzes the last step of abscisic acid biosynthesis, and (4) xanthine dehydrogenase is essential for purine degradation and stress response.
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Affiliation(s)
- Günter Schwarz
- Institute of Plant Biology, Technical University Braunschweig, 38023 Braunschweig, Germany.
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33
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Abstract
Molybdenum and tungsten are available to all organisms, with molybdenum having the far greater abundance and availability. Molybdenum occurs in a wide range of metalloenzymes in bacteria, fungi, algae, plants and animals, while tungsten was found to be essential only for a limited range of bacteria. In order to gain biological activity, molybdenum has to be complexed by a pterin compound, thus forming a molybdenum cofactor. In this article I will review the way that molybdenum takes from uptake into the cell, via formation of the molybdenum cofactor and its storage, to the final modification of molybdenum cofactor and its insertion into apo-metalloenzymes.
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Affiliation(s)
- Ralf R Mendel
- Department of Plant Biology Technical University of Braunschweig, Humboldtstrasse 1, D-38106, Braunschweig, Germany.
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34
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Llamas A, Mendel RR, Schwarz G. Synthesis of adenylated molybdopterin: an essential step for molybdenum insertion. J Biol Chem 2004; 279:55241-6. [PMID: 15504727 DOI: 10.1074/jbc.m409862200] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The molybdenum cofactor (Moco) is part of the active site of all molybdenum (Mo)-dependent enzymes, except nitrogenase. Moco consists of molybdopterin (MPT), a phosphorylated pyranopterin with an enedithiolate coordinating Mo and it is synthesized by an evolutionary old multistep pathway. The plant protein Cnx1 from Arabidopsis thaliana catalyzes with its two domains (E and G) the terminal step of Moco biosynthesis, the insertion of Mo into MPT. Recently, the high-resolution MPT-bound structure of the Cnx1 G domain (Cnx1G) has been determined (Kuper, J., Llamas, A., Hecht, H. J., Mendel, R. R., and Schwarz, G. (2004) Nature 430, 803-806). Besides defining the MPT-binding site a novel and unexpected modification of MPT has been identified, adenylated MPT. Here we demonstrate that it is Cnx1G that catalyzes the adenylation of MPT. In vitro synthesized MPT was quantitatively transferred from Escherichia coli MPT synthase to Cnx1G. The subsequent adenylation reaction by Cnx1G was Mg(2+)- and ATP-dependent. Whereas Mn(2+) could partially replace Mg(2+), ATP was the only nucleotide accepted by Cnx1G. Consequently the formation of pyrophosphate was demonstrated, which was dependent on the ability of Cnx1G to bind MPT. Pyrophosphate, either formed in the reaction or added externally, inhibited the Cnx1G-catalyzed MPT adenylation reaction. Catalytically inactive Cnx1G mutant variants showed impaired MPT adenylation confirming that MPT-AMP is the reaction product of Cnx1G. Therefore Cnx1G is a MPT adenylyltransferase catalyzing the activation of MPT, a universal reaction in the Moco synthetic pathway because Cnx1G is able to reconstitute also bacterial and mammalian Moco biosynthesis.
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Affiliation(s)
- Angel Llamas
- Department of Plant Biology, Technical University of Braunschweig, Spielmannstrasse 7, D-3806 Braunschweig, Germany
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Garattini E, Mendel R, Romão MJ, Wright R, Terao M. Mammalian molybdo-flavoenzymes, an expanding family of proteins: structure, genetics, regulation, function and pathophysiology. Biochem J 2003; 372:15-32. [PMID: 12578558 PMCID: PMC1223366 DOI: 10.1042/bj20030121] [Citation(s) in RCA: 189] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2003] [Revised: 02/04/2003] [Accepted: 02/10/2003] [Indexed: 12/11/2022]
Abstract
The molybdo-flavoenzymes are structurally related proteins that require a molybdopterin cofactor and FAD for their catalytic activity. In mammals, four enzymes are known: xanthine oxidoreductase, aldehyde oxidase and two recently described mouse proteins known as aldehyde oxidase homologue 1 and aldehyde oxidase homologue 2. The present review article summarizes current knowledge on the structure, enzymology, genetics, regulation and pathophysiology of mammalian molybdo-flavoenzymes. Molybdo-flavoenzymes are structurally complex oxidoreductases with an equally complex mechanism of catalysis. Our knowledge has greatly increased due to the recent crystallization of two xanthine oxidoreductases and the determination of the amino acid sequences of many members of the family. The evolution of molybdo-flavoenzymes can now be traced, given the availability of the structures of the corresponding genes in many organisms. The genes coding for molybdo-flavoenzymes are expressed in a cell-specific fashion and are controlled by endogenous and exogenous stimuli. The recent cloning of the genes involved in the biosynthesis of the molybdenum cofactor has increased our knowledge on the assembly of the apo-forms of molybdo-flavoproteins into the corresponding holo-forms. Xanthine oxidoreductase is the key enzyme in the catabolism of purines, although recent data suggest that the physiological function of this enzyme is more complex than previously assumed. The enzyme has been implicated in such diverse pathological situations as organ ischaemia, inflammation and infection. At present, very little is known about the pathophysiological relevance of aldehyde oxidase, aldehyde oxidase homologue 1 and aldehyde oxidase homologue 2, which do not as yet have an accepted endogenous substrate.
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Affiliation(s)
- Enrico Garattini
- Laboratory of Molecular Biology, Istituto di Ricerche Farmacologiche Mario Negri, via Eritrea 62, 20157 Milan, Italy.
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Ataya FS, Witte CP, Galván A, Igeño MI, Fernández E. Mcp1 encodes the molybdenum cofactor carrier protein in Chlamydomonas reinhardtii and participates in protection, binding, and storage functions of the cofactor. J Biol Chem 2003; 278:10885-90. [PMID: 12519777 DOI: 10.1074/jbc.m211320200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The molybdenum cofactor (Moco) is essential for the activity of all molybdoenzymes except nitrogenase. The cDNA for the Moco carrier protein (MocoCP) of Chlamydomonas reinhardtii has been cloned by reverse transcription PCR approaches with primers designed from microsequenced peptides of this protein. The C. reinhardtii MocoCP has been expressed in Escherichia coli. The recombinant protein has been purified to electrophoretic homogeneity and is found assembled into a homotetramer when Moco is not present under native conditions. Recombinant MocoCP has the same biochemical characteristics as MocoCP from C. reinhardtii, as it bound Moco from milk xanthine oxidase with high affinity, prevented Moco inactivation by oxygen, and transferred Moco efficiently to aponitrate reductase from the Neurospora crassa nit1 mutant. The genomic DNA sequence corresponding to the Chlamydomonas MocoCP gene, CrMcp1, also was isolated. This gene contained three introns in the coding region. The deduced amino acid sequence of CrMcp1 did not show a significant identity to functionally known proteins in the GenBank data base, although a significant conservation was found with bacterial proteins of unknown function. The results suggest that proteins having a Moco binding function probably exist in other organisms.
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Affiliation(s)
- Farid Shokry Ataya
- Departamento de Bioquimica y Biologia Molecular, Universidad de Córdoba, Campus de Rabanales, Edificio Severo Ochoa, Córdoba 14071, Spain
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Magalon A, Frixon C, Pommier J, Giordano G, Blasco F. In vivo interactions between gene products involved in the final stages of molybdenum cofactor biosynthesis in Escherichia coli. J Biol Chem 2002; 277:48199-204. [PMID: 12372836 DOI: 10.1074/jbc.m205806200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The final stages of bacterial molybdenum cofactor (Moco) biosynthesis correspond to molybdenum chelation and nucleotide attachment onto an unique and ubiquitous structure, the molybdopterin. Using a bacterial two-hybrid approach, here we report on the in vivo interactions between MogA, MoeA, MobA, and MobB implicated in several distinct although linked steps in Escherichia coli. Numerous interactions among these proteins have been identified. Somewhat surprisingly, MobB, a GTPase with a yet unclear function, interacts with MogA, MoeA, and MobA. Probing the effects of various mo. mutations on the interaction map allowed us (i) to distinguish Moco-sensitive interactants from insensitive ones involving MobB and (ii) to demonstrate that molybdopterin is a key molecule triggering or facilitating MogA-MoeA and MoeA-MobA interactions. These results suggest that, in vivo, molybdenum cofactor biosynthesis occurs on protein complexes rather than by the separate action of molybdenum cofactor biosynthetic proteins.
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Affiliation(s)
- Axel Magalon
- Laboratoire de Chimie Bactérienne, Institut Biologie Structurale et Microbiologie, CNRS, 31 chemin Joseph Aiguier, 13402 Marseille cedex 09, France.
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Sagi M, Scazzocchio C, Fluhr R. The absence of molybdenum cofactor sulfuration is the primary cause of the flacca phenotype in tomato plants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2002; 31:305-17. [PMID: 12164810 DOI: 10.1046/j.1365-313x.2002.01363.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The molybdenum cofactor (MoCo)-containing enzymes aldehyde oxidase (AO; EC 1.2.3.1) and xanthine dehydrogenase (XDH; EC 1.2.1.37) require for activity a sulfuration step that inserts a terminal sulfur ligand into the MoCo. The tomato flacca mutation was originally isolated as a wilty phenotype due to a lack of abscisic acid (ABA) that is related to simultaneous loss of AO and XDH activities. An expressed sequence tag candidate from tomato was selected on the basis of homology to sulfurases from animals, fungi and the recently isolated Arabidopsis genes LOS5/ABA3. The tomato homologue maps as a single gene to the bottom of chromosome 7, consistent with the genetic location of the flacca mutation. The structure of FLACCA shows a multidomain protein with an N-terminal NifS-like sulfurase domain; a mammal-specific intermediate section; and a C-terminus containing conserved motifs. Prominent among these are molybdopterin oxidoreductases and thioredoxin redox-active centre/iron-sulfur-binding region signatures which may be relevant to the specific sulfuration of MoCo. Indeed, the molecular analysis of flacca identifies the mutation in a highly conserved motif located in the C-terminus. Activity gel assays show that FLACCA is expressed throughout the plant. Transient and stable complementation of flacca and the Arabidopsis aba3 mutants with Aspergillus nidulans hxB and FLACCA yielded full, partial and tissue-specific types of Mo-hydroxylase activities. Restoration of activity in the root alone is sufficient to augment plant ABA content and rectify the wild-type phenotype. Thus the pleiotropic flacca phenotype is due to the loss of activity of enzymes requiring a sulfurated MoCo.
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Affiliation(s)
- Moshe Sagi
- The Institute for Applied Research, Ben-Gurion University, Beer Sheva 84105, Israel
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