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Maniero RA, Picco C, Hartmann A, Engelberger F, Gradogna A, Scholz-Starke J, Melzer M, Künze G, Carpaneto A, von Wirén N, Giehl RFH. Ferric reduction by a CYBDOM protein counteracts increased iron availability in root meristems induced by phosphorus deficiency. Nat Commun 2024; 15:422. [PMID: 38212310 PMCID: PMC10784544 DOI: 10.1038/s41467-023-43912-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 11/23/2023] [Indexed: 01/13/2024] Open
Abstract
To mobilize sparingly available phosphorus (P) in the rhizosphere, many plant species secrete malate to release P sorbed onto (hydr)oxides of aluminum and iron (Fe). In the presence of Fe, malate can provoke Fe over-accumulation in the root apoplast, triggering a series of events that inhibit root growth. Here, we identified HYPERSENSITIVE TO LOW P1 (HYP1), a CYBDOM protein constituted of a DOMON and a cytochrome b561 domain, as critical to maintain cell elongation and meristem integrity under low P. We demonstrate that HYP1 mediates ascorbate-dependent trans-plasma membrane electron transport and can reduce ferric and cupric substrates in Xenopus laevis oocytes and in planta. HYP1 expression is up-regulated in response to P deficiency in the proximal zone of the root apical meristem. Disruption of HYP1 leads to increased Fe and callose accumulation in the root meristem and causes significant transcriptional changes in roots. We further demonstrate that HYP1 activity overcomes malate-induced Fe accumulation, thereby preventing Fe-dependent root growth arrest in response to low P. Collectively, our results uncover an ascorbate-dependent metalloreductase that is critical to protect root meristems of P-deficient plants from increased Fe availability and provide insights into the physiological function of the yet poorly characterized but ubiquitous CYBDOM proteins.
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Affiliation(s)
- Rodolfo A Maniero
- Leibniz Institute of Plant Genetics & Crop Plant Research (IPK) OT Gatersleben, Corrensstr 3, 06466, Seeland, Germany
| | - Cristiana Picco
- Institute of Biophysics, National Research Council, Via De Marini 16, 16149, Genoa, Italy
| | - Anja Hartmann
- Leibniz Institute of Plant Genetics & Crop Plant Research (IPK) OT Gatersleben, Corrensstr 3, 06466, Seeland, Germany
| | - Felipe Engelberger
- Institute for Drug Discovery, Leipzig University, SAC 04103, Leipzig, Germany
| | - Antonella Gradogna
- Institute of Biophysics, National Research Council, Via De Marini 16, 16149, Genoa, Italy
| | - Joachim Scholz-Starke
- Institute of Biophysics, National Research Council, Via De Marini 16, 16149, Genoa, Italy
| | - Michael Melzer
- Leibniz Institute of Plant Genetics & Crop Plant Research (IPK) OT Gatersleben, Corrensstr 3, 06466, Seeland, Germany
| | - Georg Künze
- Institute for Drug Discovery, Leipzig University, SAC 04103, Leipzig, Germany
- Center for Scalable Data Analytics and Artificial Intelligence, Leipzig University, 04105, Leipzig, Germany
- Interdisciplinary Center for Bioinformatics, Leipzig University, 04107, Leipzig, Germany
| | - Armando Carpaneto
- Institute of Biophysics, National Research Council, Via De Marini 16, 16149, Genoa, Italy
- Department of Earth, Environment and Life Sciences (DISTAV), University of Genoa, Viale Benedetto XV 5, 16132, Genoa, Italy
| | - Nicolaus von Wirén
- Leibniz Institute of Plant Genetics & Crop Plant Research (IPK) OT Gatersleben, Corrensstr 3, 06466, Seeland, Germany
| | - Ricardo F H Giehl
- Leibniz Institute of Plant Genetics & Crop Plant Research (IPK) OT Gatersleben, Corrensstr 3, 06466, Seeland, Germany.
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2
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Clúa J, Montpetit J, Jimenez-Sandoval P, Naumann C, Santiago J, Poirier Y. A CYBDOM protein impacts iron homeostasis and primary root growth under phosphate deficiency in Arabidopsis. Nat Commun 2024; 15:423. [PMID: 38212368 PMCID: PMC10784552 DOI: 10.1038/s41467-023-43911-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 11/23/2023] [Indexed: 01/13/2024] Open
Abstract
Arabidopsis primary root growth response to phosphate (Pi) deficiency is mainly controlled by changes in apoplastic iron (Fe). Upon Pi deficiency, apoplastic Fe deposition in the root apical meristem activates pathways leading to the arrest of meristem maintenance and inhibition of cell elongation. Here, we report that a member of the uncharacterized cytochrome b561 and DOMON domain (CYBDOM) protein family, named CRR, promotes iron reduction in an ascorbate-dependent manner and controls apoplastic iron deposition. Under low Pi, the crr mutant shows an enhanced reduction of primary root growth associated with increased apoplastic Fe in the root meristem and a reduction in meristematic cell division. Conversely, CRR overexpression abolishes apoplastic Fe deposition rendering primary root growth insensitive to low Pi. The crr single mutant and crr hyp1 double mutant, harboring a null allele in another member of the CYDOM family, shows increased tolerance to high-Fe stress upon germination and seedling growth. Conversely, CRR overexpression is associated with increased uptake and translocation of Fe to the shoot and results in plants highly sensitive to Fe excess. Our results identify a ferric reductase implicated in Fe homeostasis and developmental responses to abiotic stress, and reveal a biological role for CYBDOM proteins in plants.
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Affiliation(s)
- Joaquín Clúa
- Department of Plant Molecular Biology, Biophore Building, University of Lausanne, 1015, Lausanne, Switzerland
| | - Jonatan Montpetit
- Department of Plant Molecular Biology, Biophore Building, University of Lausanne, 1015, Lausanne, Switzerland
| | - Pedro Jimenez-Sandoval
- Department of Plant Molecular Biology, Biophore Building, University of Lausanne, 1015, Lausanne, Switzerland
| | - Christin Naumann
- Department of Molecular Signal Processing, Leibniz Institute of Plant Biochemistry, Weinberg 3, 06120, Halle, Germany
| | - Julia Santiago
- Department of Plant Molecular Biology, Biophore Building, University of Lausanne, 1015, Lausanne, Switzerland
| | - Yves Poirier
- Department of Plant Molecular Biology, Biophore Building, University of Lausanne, 1015, Lausanne, Switzerland.
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Bérczi A, Márton Z, Laskay K, Tóth A, Rákhely G, Duzs Á, Sebők-Nagy K, Páli T, Zimányi L. Spectral and Redox Properties of a Recombinant Mouse Cytochrome b561 Protein Suggest Transmembrane Electron Transfer Function. Molecules 2023; 28:molecules28052261. [PMID: 36903505 PMCID: PMC10005133 DOI: 10.3390/molecules28052261] [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: 02/02/2023] [Revised: 02/23/2023] [Accepted: 02/27/2023] [Indexed: 03/05/2023] Open
Abstract
Cytochrome b561 proteins (CYB561s) are integral membrane proteins with six trans-membrane domains, two heme-b redox centers, one on each side of the host membrane. The major characteristics of these proteins are their ascorbate reducibility and trans-membrane electron transferring capability. More than one CYB561 can be found in a wide range of animal and plant phyla and they are localized in membranes different from the membranes participating in bioenergization. Two homologous proteins, both in humans and rodents, are thought to participate-via yet unidentified way-in cancer pathology. The recombinant forms of the human tumor suppressor 101F6 protein (Hs_CYB561D2) and its mouse ortholog (Mm_CYB561D2) have already been studied in some detail. However, nothing has yet been published about the physical-chemical properties of their homologues (Hs_CYB561D1 in humans and Mm_CYB561D1 in mice). In this paper we present optical, redox and structural properties of the recombinant Mm_CYB561D1, obtained based on various spectroscopic methods and homology modeling. The results are discussed in comparison to similar properties of the other members of the CYB561 protein family.
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Affiliation(s)
- Alajos Bérczi
- Institute of Biophysics, Biological Research Centre Szeged, H-6726 Szeged, Hungary
| | - Zsuzsanna Márton
- Institute of Biophysics, Biological Research Centre Szeged, H-6726 Szeged, Hungary
| | - Krisztina Laskay
- Institute of Biophysics, Biological Research Centre Szeged, H-6726 Szeged, Hungary
| | - András Tóth
- Institute of Biophysics, Biological Research Centre Szeged, H-6726 Szeged, Hungary
- Department of Biotechnology, University of Szeged, H-6726 Szeged, Hungary
| | - Gábor Rákhely
- Institute of Biophysics, Biological Research Centre Szeged, H-6726 Szeged, Hungary
- Department of Biotechnology, University of Szeged, H-6726 Szeged, Hungary
| | - Ágnes Duzs
- Institute of Biophysics, Biological Research Centre Szeged, H-6726 Szeged, Hungary
- Department of Biotechnology, University of Szeged, H-6726 Szeged, Hungary
| | - Krisztina Sebők-Nagy
- Institute of Biophysics, Biological Research Centre Szeged, H-6726 Szeged, Hungary
| | - Tibor Páli
- Institute of Biophysics, Biological Research Centre Szeged, H-6726 Szeged, Hungary
| | - László Zimányi
- Institute of Biophysics, Biological Research Centre Szeged, H-6726 Szeged, Hungary
- Correspondence:
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Liu Y, Vasina VV, Kraner ME, Peters WS, Sonnewald U, Knoblauch M. Proteomics of isolated sieve tubes from Nicotiana tabacum: sieve element-specific proteins reveal differentiation of the endomembrane system. Proc Natl Acad Sci U S A 2022; 119:e2112755119. [PMID: 34983847 PMCID: PMC8740716 DOI: 10.1073/pnas.2112755119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/18/2021] [Indexed: 11/30/2022] Open
Abstract
Symplasmicly connected cells called sieve elements form a network of tubes in the phloem of vascular plants. Sieve elements have essential functions as they provide routes for photoassimilate distribution, the exchange of developmental signals, and the coordination of defense responses. Nonetheless, they are the least understood main type of plant cells. They are extremely sensitive, possess a reduced endomembrane system without Golgi apparatus, and lack nuclei and translation machineries, so that transcriptomics and similar techniques cannot be applied. Moreover, the analysis of phloem exudates as a proxy for sieve element composition is marred by methodological problems. We developed a simple protocol for the isolation of sieve elements from leaves and stems of Nicotiana tabacum at sufficient amounts for large-scale proteome analysis. By quantifying the enrichment of individual proteins in purified sieve element relative to bulk phloem preparations, proteins of increased likelyhood to function specifically in sieve elements were identified. To evaluate the validity of this approach, yellow fluorescent protein constructs of genes encoding three of the candidate proteins were expressed in plants. Tagged proteins occurred exclusively in sieve elements. Two of them, a putative cytochrome b561/ferric reductase and a reticulon-like protein, appeared restricted to segments of the endoplasmic reticulum (ER) that were inaccessible to green fluorescent protein dissolved in the ER lumen, suggesting a previously unknown differentiation of the endomembrane system in sieve elements. Evidently, our list of promising candidate proteins ( SI Appendix, Table S1) provides a valuable exploratory tool for sieve element biology.
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Affiliation(s)
- Yan Liu
- School of Biological Sciences, Washington State University, Pullman, WA 99154
| | - Viktoriya V Vasina
- School of Biological Sciences, Washington State University, Pullman, WA 99154
| | - Max E Kraner
- Division of Biochemistry, Department of Biology, Friedrich-Alexander-University Erlangen-Nuremberg, 91058 Erlangen, Germany
| | - Winfried S Peters
- School of Biological Sciences, Washington State University, Pullman, WA 99154
- Department of Biology, Purdue University Fort Wayne, Fort Wayne, IN 46835
| | - Uwe Sonnewald
- Division of Biochemistry, Department of Biology, Friedrich-Alexander-University Erlangen-Nuremberg, 91058 Erlangen, Germany
| | - Michael Knoblauch
- School of Biological Sciences, Washington State University, Pullman, WA 99154;
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Hoang MTT, Almeida D, Chay S, Alcon C, Corratge-Faillie C, Curie C, Mari S. AtDTX25, a member of the multidrug and toxic compound extrusion family, is a vacuolar ascorbate transporter that controls intracellular iron cycling in Arabidopsis. THE NEW PHYTOLOGIST 2021; 231:1956-1967. [PMID: 34080200 DOI: 10.1111/nph.17526] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 05/20/2021] [Indexed: 06/12/2023]
Abstract
Iron (Fe) is an essential element, its transport is regulated by the cell redox balance. In seeds, Fe enters the embryo as Fe2+ and is stored in vacuoles as Fe3+ . Through its ferric reduction activity, ascorbate plays a major role in Fe redox state and therefore Fe transport within the seed. We searched for ascorbate membrane transporters responsible for controlling Fe reduction by screening the yeast ferric reductase-deficient fre1 strain and isolated AtDTX25, a member of the Multidrug And Toxic compound Extrusion (MATE) family. AtDTX25 was shown to mediate ascorbate efflux when expressed in yeast and Xenopus oocytes, in a pH-dependent manner. In planta, AtDTX25 is highly expressed during germination and encodes a vacuolar membrane protein. Isolated vacuoles from AtDTX25-1 knockout mutant contained less ascorbate and more Fe than wild-type (WT), and mutant seedlings were highly sensitive to Fe deficiency. Iron imaging further showed that the remobilisation of Fe from vacuoles was highly impaired in mutant seedlings. Taken together, our results established AtDTX25 as a vacuolar ascorbate transporter, required during germination to promote the reduction of the pool of stored Fe3+ and its remobilisation to feed the developing seedling.
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Affiliation(s)
- Minh Thi Thanh Hoang
- BPMP, Université Montpellier, CNRS, INRAE, Institut Agro, Montpellier, F-34060, France
| | - Diego Almeida
- BPMP, Université Montpellier, CNRS, INRAE, Institut Agro, Montpellier, F-34060, France
| | - Sandrine Chay
- BPMP, Université Montpellier, CNRS, INRAE, Institut Agro, Montpellier, F-34060, France
| | - Carine Alcon
- BPMP, Université Montpellier, CNRS, INRAE, Institut Agro, Montpellier, F-34060, France
| | | | - Catherine Curie
- BPMP, Université Montpellier, CNRS, INRAE, Institut Agro, Montpellier, F-34060, France
| | - Stephane Mari
- BPMP, Université Montpellier, CNRS, INRAE, Institut Agro, Montpellier, F-34060, France
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6
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Balaji S. The transferred translocases: An old wine in a new bottle. Biotechnol Appl Biochem 2021; 69:1587-1610. [PMID: 34324237 DOI: 10.1002/bab.2230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 07/23/2021] [Indexed: 11/12/2022]
Abstract
The role of translocases was underappreciated and was not included as a separate class in the enzyme commission until August 2018. The recent research interests in proteomics of orphan enzymes, ionomics, and metallomics along with high-throughput sequencing technologies generated overwhelming data and revamped this enzyme into a separate class. This offers a great opportunity to understand the role of new or orphan enzymes in general and specifically translocases. The enzymes belonging to translocases regulate/permeate the transfer of ions or molecules across the membranes. These enzyme entries were previously associated with other enzyme classes, which are now transferred to a new enzyme class 7 (EC 7). The entries that are reclassified are important to extend the enzyme list, and it is the need of the hour. Accordingly, there is an upgradation of entries of this class of enzymes in several databases. This review is a concise compilation of translocases with reference to the number of entries currently available in the databases. This review also focuses on function as well as dysfunction of translocases during normal and disordered states, respectively.
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Affiliation(s)
- S Balaji
- Department of Biotechnology, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal, Karnataka, 576 104, India
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7
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Functional Assembly of Caenorhabditis elegans Cytochrome b-2 (Cecytb-2) into Phospholipid Bilayer Nanodisc with Enhanced Iron Reductase Activity. Biomolecules 2021; 11:biom11010096. [PMID: 33451048 PMCID: PMC7828500 DOI: 10.3390/biom11010096] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 01/07/2021] [Accepted: 01/12/2021] [Indexed: 12/14/2022] Open
Abstract
Among seven homologs of cytochrome b561 in a model organism C. elegans, Cecytb-2 was confirmed to be expressed in digestive organs and was considered as a homolog of human Dcytb functioning as a ferric reductase. Cecytb-2 protein was expressed in Pichia pastoris cells, purified, and reconstituted into a phospholipid bilayer nanodisc. The reconstituted Cecytb-2 in nanodisc environments was extremely stable and more reducible with ascorbate than in a detergent-micelle state. We confirmed the ferric reductase activity of Cecytb-2 by analyzing the oxidation of ferrous heme upon addition of ferric substrate under anaerobic conditions, where clear and saturable dependencies on the substrate concentrations following the Michaelis–Menten equation were observed. Further, we confirmed that the ferric substrate was converted to a ferrous state by using a nitroso-PSAP assay. Importantly, we observed that the ferric reductase activity of Cecytb-2 became enhanced in the phospholipid bilayer nanodisc.
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Klein M, Deniz E, Heit S, Wille G, Mäntele W, Lancaster CRD. Proton-Coupled Electron Transport in Two Distinct CYBASC Paralogs of Arabidopsis thaliana: A Comparative Characterization of Highly Conserved Tyrosine and Lysine Residues. Biochemistry 2020; 59:2328-2339. [PMID: 32428401 DOI: 10.1021/acs.biochem.0c00155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
CYBASC proteins are ascorbate (AscH-) reducible, diheme b-containing integral membrane cytochrome b561 proteins (cytb561), which are proposed to be involved in AscH- recycling and facilitation of iron absorption. Two distinct CYBASC paralogs from the plant Arabidopsis thaliana, Atcytb561-A (A-paralog) and Atcytb561-B (B-paralog), have been found to differ in their visible-spectral characteristics and their interaction with AscH- and ferric iron chelates. A previously determined crystal structure of the B-paralog provides the first insights into the structural organization of a CYBASC member and implies hydrogen bonding between the substrate AscH- and the conserved lysine residues at positions 77 (B-K77) and 81 (B-K81). The function of the highly conserved tyrosine at position 70 (B-Y70) is not obvious in the crystal structure, but its localization indicates the possible involvement in proton-coupled electron transfer. Here we show that B-Y70 plays a major role in the modulation of the oxidation-reduction midpoint potential of the high-potential heme, EM(bH), as well as in AscH- oxidation. Our results support the involvement of the functionally conserved B-K77 in the stabilization of the dianion Asc2-. These findings are supported by the crystal structure of the B-paralog, but a comparative biochemical and biophysical characterization of the A- and B-paralogs implied distinct and more complex functions of the corresponding residues A-Y69 and A-K76 in the A-paralog. Our results emphasize the need for a high-resolution crystal structure of the A-paralog to illuminate the differences in functional organization between the two paralogs.
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Affiliation(s)
- Martin Klein
- Saarland University, Department of Structural Biology, Institute of Biophysics, Center of Human and Molecular Biology (ZHMB), Faculty of Medicine, Building 60, D-66421 Homburg, Germany
| | - Erhan Deniz
- Goethe University, Institute of Biophysics, Max-von-Laue Straße 1, D-60438 Frankfurt, Germany
| | - Sabine Heit
- Saarland University, Department of Structural Biology, Institute of Biophysics, Center of Human and Molecular Biology (ZHMB), Faculty of Medicine, Building 60, D-66421 Homburg, Germany
| | - Georg Wille
- Goethe University, Institute of Biophysics, Max-von-Laue Straße 1, D-60438 Frankfurt, Germany
| | - Werner Mäntele
- Goethe University, Institute of Biophysics, Max-von-Laue Straße 1, D-60438 Frankfurt, Germany
| | - C Roy D Lancaster
- Saarland University, Department of Structural Biology, Institute of Biophysics, Center of Human and Molecular Biology (ZHMB), Faculty of Medicine, Building 60, D-66421 Homburg, Germany
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El Behery M, Fujimura M, Kimura T, Tsubaki M. Direct measurements of ferric reductase activity of human 101F6 and its enhancement upon reconstitution into phospholipid bilayer nanodisc. Biochem Biophys Rep 2020; 21:100730. [PMID: 32055716 PMCID: PMC7005374 DOI: 10.1016/j.bbrep.2020.100730] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 12/21/2019] [Accepted: 01/08/2020] [Indexed: 12/11/2022] Open
Abstract
We studied human 101F6 protein to clarify its physiological function as a ferric reductase and its relationship to tumor suppression activity. We found for the first time that purified 101F6 both in detergent micelle state and in phospholipid bilayer nanodisc state has an authentic ferric reductase activity by single turnover kinetic analyses. The kinetic analysis on the ferrous heme oxidation of reduced 101F6 upon the addition of a ferric substrate, ferric ammonium citrate (FAC), showed concentration-dependent accelerations of its reaction with reasonable values of KM and Vmax. We further verified the authenticity of the ferric reductase activity of 101F6 using nitroso-PSAP as a Fe2+-specific colorimetric chelator. 101F6 in nanodisc state showed higher efficiency for FAC than in detergent micelle state. Human tumor suppressor 101F6 protein was reconstituted into nanodisc. 101F6 functions as a ferric reductase both in detergent micelle and in nanodisc. 101F6 in nanodisc showed higher efficiency in the reductase activity.
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Affiliation(s)
- Mohammed El Behery
- Department of Chemistry, Graduate School of Science, Kobe University, Nada-ku, Kobe, Hyogo, 657-8501, Japan
| | - Mika Fujimura
- Department of Chemistry, Graduate School of Science, Kobe University, Nada-ku, Kobe, Hyogo, 657-8501, Japan
| | - Tetsunari Kimura
- Department of Chemistry, Graduate School of Science, Kobe University, Nada-ku, Kobe, Hyogo, 657-8501, Japan
| | - Motonari Tsubaki
- Department of Chemistry, Graduate School of Science, Kobe University, Nada-ku, Kobe, Hyogo, 657-8501, Japan
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Lelandais G, Scheiber I, Paz-Yepes J, Lozano JC, Botebol H, Pilátová J, Žárský V, Léger T, Blaiseau PL, Bowler C, Bouget FY, Camadro JM, Sutak R, Lesuisse E. Ostreococcus tauri is a new model green alga for studying iron metabolism in eukaryotic phytoplankton. BMC Genomics 2016; 17:319. [PMID: 27142620 PMCID: PMC4855317 DOI: 10.1186/s12864-016-2666-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 04/26/2016] [Indexed: 11/17/2022] Open
Abstract
Background Low iron bioavailability is a common feature of ocean surface water and therefore micro-algae developed original strategies to optimize iron uptake and metabolism. The marine picoeukaryotic green alga Ostreococcus tauri is a very good model for studying physiological and genetic aspects of the adaptation of the green algal lineage to the marine environment: it has a very compact genome, is easy to culture in laboratory conditions, and can be genetically manipulated by efficient homologous recombination. In this study, we aimed at characterizing the mechanisms of iron assimilation in O. tauri by combining genetics and physiological tools. Specifically, we wanted to identify and functionally characterize groups of genes displaying tightly orchestrated temporal expression patterns following the exposure of cells to iron deprivation and day/night cycles, and to highlight unique features of iron metabolism in O. tauri, as compared to the freshwater model alga Chalamydomonas reinhardtii. Results We used RNA sequencing to investigated the transcriptional responses to iron limitation in O. tauri and found that most of the genes involved in iron uptake and metabolism in O. tauri are regulated by day/night cycles, regardless of iron status. O. tauri lacks the classical components of a reductive iron uptake system, and has no obvious iron regulon. Iron uptake appears to be copper-independent, but is regulated by zinc. Conversely, iron deprivation resulted in the transcriptional activation of numerous genes encoding zinc-containing regulation factors. Iron uptake is likely mediated by a ZIP-family protein (Ot-Irt1) and by a new Fea1-related protein (Ot-Fea1) containing duplicated Fea1 domains. The adaptation of cells to iron limitation involved an iron-sparing response tightly coordinated with diurnal cycles to optimize cell functions and synchronize these functions with the day/night redistribution of iron orchestrated by ferritin, and a stress response based on the induction of thioredoxin-like proteins, of peroxiredoxin and of tesmin-like methallothionein rather than ascorbate. We briefly surveyed the metabolic remodeling resulting from iron deprivation. Conclusions The mechanisms of iron uptake and utilization by O. tauri differ fundamentally from those described in C. reinhardtii. We propose this species as a new model for investigation of iron metabolism in marine microalgae. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2666-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Gaëlle Lelandais
- CNRS, Institut Jacques Monod, Université Paris Diderot-Paris 7, F-75013, Paris, France
| | - Ivo Scheiber
- Department of Parasitology, Faculty of Science, Charles University in Prague, 12844, Prague, Czech Republic
| | - Javier Paz-Yepes
- Ecole Normale Supérieure, PSL Research University, Institut de Biologie de l'Ecole Normale Supérieure (IBENS), CNRS UMR 8197, INSERM U1024, 46 rue d'Ulm, F-75005, Paris, France
| | - Jean-Claude Lozano
- Sorbonne Universités, University Pierre et Marie Curie, University of Paris VI, CNRS, Laboratoire d'Océanographie Microbienne, Observatoire Océanologique, F-66650, Banyuls-sur-Mer, France
| | - Hugo Botebol
- Sorbonne Universités, University Pierre et Marie Curie, University of Paris VI, CNRS, Laboratoire d'Océanographie Microbienne, Observatoire Océanologique, F-66650, Banyuls-sur-Mer, France
| | - Jana Pilátová
- Department of Parasitology, Faculty of Science, Charles University in Prague, 12844, Prague, Czech Republic
| | - Vojtěch Žárský
- Department of Parasitology, Faculty of Science, Charles University in Prague, 12844, Prague, Czech Republic
| | - Thibaut Léger
- CNRS, Institut Jacques Monod, Université Paris Diderot-Paris 7, F-75013, Paris, France
| | - Pierre-Louis Blaiseau
- Sorbonne Universités, University Pierre et Marie Curie, University of Paris VI, CNRS, Laboratoire d'Océanographie Microbienne, Observatoire Océanologique, F-66650, Banyuls-sur-Mer, France
| | - Chris Bowler
- Ecole Normale Supérieure, PSL Research University, Institut de Biologie de l'Ecole Normale Supérieure (IBENS), CNRS UMR 8197, INSERM U1024, 46 rue d'Ulm, F-75005, Paris, France
| | - François-Yves Bouget
- Sorbonne Universités, University Pierre et Marie Curie, University of Paris VI, CNRS, Laboratoire d'Océanographie Microbienne, Observatoire Océanologique, F-66650, Banyuls-sur-Mer, France
| | - Jean-Michel Camadro
- CNRS, Institut Jacques Monod, Université Paris Diderot-Paris 7, F-75013, Paris, France
| | - Robert Sutak
- Department of Parasitology, Faculty of Science, Charles University in Prague, 12844, Prague, Czech Republic.
| | - Emmanuel Lesuisse
- CNRS, Institut Jacques Monod, Université Paris Diderot-Paris 7, F-75013, Paris, France.
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Mentewab A, Matheson K, Adebiyi M, Robinson S, Elston B. RNA-seq analysis of the effect of kanamycin and the ABC transporter AtWBC19 on Arabidopsis thaliana seedlings reveals changes in metal content. PLoS One 2014; 9:e109310. [PMID: 25310285 PMCID: PMC4195610 DOI: 10.1371/journal.pone.0109310] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2014] [Accepted: 09/09/2014] [Indexed: 11/19/2022] Open
Abstract
Plants are exposed to antibiotics produced by soil microorganisms, but little is known about their responses at the transcriptional level. Likewise, few endogenous mechanisms of antibiotic resistance have been reported. The Arabidopsis thaliana ATP Binding Cassette (ABC) transporter AtWBC19 (ABCG19) is known to confer kanamycin resistance, but the exact mechanism of resistance is not well understood. Here we examined the transcriptomes of control seedlings and wbc19 mutant seedlings using RNA-seq analysis. Exposure to kanamycin indicated changes in the organization of the photosynthetic apparatus, metabolic fluxes and metal uptake. Elemental analysis showed a 60% and 80% reduction of iron uptake in control and wbc19 mutant seedlings respectively, upon exposure to kanamycin. The drop in iron content was accompanied by the upregulation of the gene encoding for FERRIC REDUCTION OXIDASE 6 (FRO6) in mutant seedlings but not by the differential expression of other transport genes known to be induced by iron deficiency. In addition, wbc19 mutants displayed a distinct expression profile in the absence of kanamycin. Most notably the expression of several zinc ion binding proteins, including ZINC TRANSPORTER 1 PRECURSOR (ZIP1) was increased, suggesting abnormal zinc uptake. Elemental analysis confirmed a 50% decrease of zinc content in wbc19 mutants. Thus, the antibiotic resistance gene WBC19 appears to also have a role in zinc uptake.
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Affiliation(s)
- Ayalew Mentewab
- Biology Department, Spelman College, Atlanta, Georgia, United States of America
- * E-mail:
| | - Kinnari Matheson
- Biology Department, Spelman College, Atlanta, Georgia, United States of America
- Molecular Biology Department, Princeton University, Princeton, New Jersey, United States of America
| | - Morayo Adebiyi
- Biology Department, Spelman College, Atlanta, Georgia, United States of America
- The Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, Texas, United States of America
| | - Shanice Robinson
- Biology Department, Spelman College, Atlanta, Georgia, United States of America
| | - Brianna Elston
- Biology Department, Spelman College, Atlanta, Georgia, United States of America
- College of Health Care Sciences, Nova Southeastern University, Davie, Florida, United States of America
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Structure and mechanism of a eukaryotic transmembrane ascorbate-dependent oxidoreductase. Proc Natl Acad Sci U S A 2014; 111:1813-8. [PMID: 24449903 DOI: 10.1073/pnas.1323931111] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Vitamin C, also known as ascorbate, is required in numerous essential metabolic reactions in eukaryotes. The eukaryotic ascorbate-dependent oxidoreductase cytochrome b561 (Cyt b561), a family of highly conserved transmembrane enzymes, plays an important role in ascorbate recycling and iron absorption. Although Cyt b561 was identified four decades ago, its atomic structure and functional mechanism remain largely unknown. Here, we report the high-resolution crystal structures of cytochrome b561 from Arabidopsis thaliana in both substrate-free and substrate-bound states. Cyt b561 forms a homodimer, with each protomer consisting of six transmembrane helices and two heme groups. The negatively charged substrate ascorbate, or monodehydroascorbate, is enclosed in a positively charged pocket on either side of the membrane. Two highly conserved amino acids, Lys(81) and His(106), play an essential role in substrate recognition and catalysis. Our structural and biochemical analyses allow the proposition of a general electron transfer mechanism for members of the Cyt b561 family.
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Asard H, Barbaro R, Trost P, Bérczi A. Cytochromes b561: ascorbate-mediated trans-membrane electron transport. Antioxid Redox Signal 2013; 19:1026-35. [PMID: 23249217 PMCID: PMC3763232 DOI: 10.1089/ars.2012.5065] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
SIGNIFICANCE Cytochromes b561 (CYB561s) constitute a family of trans-membrane (TM), di-heme proteins, occurring in a variety of organs and cell types, in plants and animals, and using ascorbate (ASC) as an electron donor. CYB561s function as monodehydroascorbate reductase, regenerating ASC, and as Fe³⁺-reductases, providing reduced iron for TM transport. A CYB561-core domain is also associated with dopamine β-monooxygenase redox domains (DOMON) in ubiquitous CYBDOM proteins. In plants, CYBDOMs form large protein families. Physiological functions supported by CYB561s and CYBDOMs include stress defense, cell wall modifications, iron metabolism, tumor suppression, and various neurological processes, including memory retention. CYB561s, therefore, significantly broaden our view on the physiological roles of ASC. RECENT ADVANCES The ubiquitous nature of CYB561s is only recently being recognized. Significant advances have been made through the study of recombinant CYB561s, revealing structural and functional properties of a unique "two-heme four-helix" protein configuration. In addition, the DOMON domains of CYBDOMs are suggested to contain another heme b. CRITICAL ISSUES New CYB561 proteins are still being identified, and there is a need to provide an insight and overview on the various roles of these proteins and their structural properties. FUTURE DIRECTIONS Mutant studies will reveal in greater detail the mechanisms by which CYB561s and CYBDOMs participate in cell metabolism in plants and animals. Moreover, the availability of efficient heterologous expression systems should allow protein crystallization, more detailed (atomic-level) structural information, and insights into the intra-molecular mechanism of electron transport.
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Affiliation(s)
- Han Asard
- Department of Biology, University of Antwerp, Antwerp, Belgium.
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14
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Lüthje S, Möller B, Perrineau FC, Wöltje K. Plasma membrane electron pathways and oxidative stress. Antioxid Redox Signal 2013; 18:2163-83. [PMID: 23265437 DOI: 10.1089/ars.2012.5130] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
SIGNIFICANCE Several redox compounds, including respiratory burst oxidase homologs (Rboh) and iron chelate reductases have been identified in animal and plant plasma membrane (PM). Studies using molecular biological, biochemical, and proteomic approaches suggest that PM redox systems of plants are involved in signal transduction, nutrient uptake, transport, and cell wall-related processes. Function of PM-bound redox systems in oxidative stress will be discussed. RECENT ADVANCES Present knowledge about the properties, structures, and functions of these systems are summarized. Judging from the currently available data, it is likely that electrons are transferred from cytosolic NAD(P)H to the apoplast via quinone reductases, vitamin K, and a cytochrome b561. In tandem with these electrons, protons might be transported to the apoplastic space. CRITICAL ISSUES Recent studies suggest localization of PM-bound redox systems in microdomains (so-called lipid or membrane rafts), but also organization of these compounds in putative and high molecular mass protein complexes. Although the plant flavocytochrome b family is well characterized with respect to its function, the molecular mechanism of an electron transfer reaction by these compounds has to be verified. Localization of Rboh in other compartments needs elucidation. FUTURE DIRECTIONS Plant members of the flavodoxin and flavodoxin-like protein family and the cytochrome b561 protein family have been characterized on the biochemical level, postulated localization, and functions of these redox compounds need verification. Compositions of single microdomains and interaction partners of PM redox systems have to be elucidated. Finally, the hypothesis of an electron transfer chain in the PM needs further proof.
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Affiliation(s)
- Sabine Lüthje
- Biocenter Klein Flottbek, University of Hamburg, Hamburg, Germany.
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15
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Tóth SZ, Schansker G, Garab G. The physiological roles and metabolism of ascorbate in chloroplasts. PHYSIOLOGIA PLANTARUM 2013; 148:161-75. [PMID: 23163968 DOI: 10.1111/ppl.12006] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Revised: 10/30/2012] [Accepted: 10/31/2012] [Indexed: 05/03/2023]
Abstract
Ascorbate is a multifunctional metabolite in plants. It is essential for growth control, involving cell division and cell wall synthesis and also involved in redox signaling, in the modulation of gene expression and regulation of enzymatic activities. Ascorbate also fulfills crucial roles in scavenging reactive oxygen species, both enzymatically and nonenzymatically, a well-established phenomenon in the chloroplasts stroma. We give an overview on these important physiological functions and would like to give emphasis to less well-known roles of ascorbate, in the thylakoid lumen, where it also plays multiple roles. It is essential for photoprotection as a cofactor for violaxanthin de-epoxidase, a key enzyme in the formation of nonphotochemical quenching. Lumenal ascorbate has recently also been shown to act as an alternative electron donor of photosystem II once the oxygen-evolving complex is inactivated and to protect the photosynthetic machinery by slowing down donor-side induced photoinactivation; it is yet to be established if ascorbate has a similar role in the case of other stress effects, such as high light and UV-B stress. In bundle sheath cells, deficient in oxygen evolution, ascorbate provides electrons to photosystem II, thereby poising cyclic electron transport around photosystem I. It has also been shown that, by supporting linear electron transport through photosystem II in sulfur-deprived Chlamydomonas reinhardtii cells, in which oxygen evolution is largely inhibited, externally added ascorbate enhances hydrogen production. For fulfilling its multiple roles, Asc has to be transported into the thylakoid lumen and efficiently regenerated; however, very little is known yet about these processes.
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Affiliation(s)
- Szilvia Z Tóth
- Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, Szeged, P.O. Box 521, H-6701, Hungary.
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16
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Roles of conserved Arg(72) and Tyr(71) in the ascorbate-specific transmembrane electron transfer catalyzed by Zea mays cytochrome b561. J Biosci Bioeng 2013; 115:497-506. [PMID: 23290447 DOI: 10.1016/j.jbiosc.2012.11.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2012] [Revised: 10/29/2012] [Accepted: 11/19/2012] [Indexed: 12/11/2022]
Abstract
Cytochromes b561, novel transmembrane electron transport proteins residing in eukaryotic cells, have a number of common features including six transmembrane α-helices and two heme ligation sites. Our recent studies on recombinant Zea mays cytochrome b561 suggested that concerted proton/electron transfer mechanism was functioning in plant cytochromes b561 as well and that conserved Lys(83) on a cytosolic loop had important roles for ascorbate-binding and a succeeding electron transfer. In the present study, we conducted site-directed mutagenesis analyses on conserved Arg(72) and Tyr(71). Removal of a positive charge at Arg(72) did not affect significantly on the final heme reduction level with ascorbate as reductant. However, characteristic pH-dependent initial time-lag upon electron acceptance from ascorbate was completely lost for R72A and R72E mutants. Substitution of Tyr(71) with Ala or Phe affected both on the final heme reduction level and on the pH-dependent initial time-lag, causing acceleration of the electron transfer. These observations were interpreted as existence of specific interactions of Tyr(71) and Arg(72) with ascorbate. However, their mechanistic roles were distinctly different from that of Lys(83), as exemplified by K83A/Y71A double mutant, and might be related for expelling of monodehydroascorbate radical from the substrate-binding site to prevent a back-flow of electrons.
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17
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Recuenco MC, Rahman MM, Sakamoto Y, Takeuchi F, Hori H, Tsubaki M. Functional characterization of the recombinant human tumour suppressor 101F6 protein, a cytochrome b(561) homologue. J Biochem 2012; 153:233-42. [PMID: 23235316 DOI: 10.1093/jb/mvs139] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Candidate human tumour suppressor gene product, 101F6 protein, is a highly hydrophobic transmembrane protein and a member of cytochrome b(561) family. Purified 101F6 protein expressed in Pichia pastoris cells showed visible absorption spectra similar but distinct from those of cytochrome b(561). Haem content analysis indicated presence of two haems B per molecule. Midpoint potentials of the purified protein were found as +109 and +26 mV for two haems, slightly lower than those for bovine chromaffin granule or plant Zea mays cytochromes b(561). Electron paramagnetic resonance (EPR) spectra in oxidized state at 5 K showed only a highly anisotropic low-spin (HALS) signal at g(z) = 3.75. However, at 15 and 20 K, another HALS-type signal appeared at g(z) = 3.65 being overlapped with that of g(z) = 3.75. The rhombic EPR signal at g(z) = 3.16 previously seen in other cytochromes b(561) was not observed, suggesting distinct haem environments. Absence of the inhibition in the electron transfer from ascorbate by a treatment of 101F6 protein with diethylpyrocarbonate showed a remarkable contrast from those of other cytochromes b(561) where the 'concerted H(+)/e(-) transfer mechanism' at the cytosolic haem centre was blocked by specific Nε-carbethoxylation of haem-coordinating imidazole, suggesting that 101F6 protein might accept electrons via a mechanism distinct from other cytochromes b(561).
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Affiliation(s)
- Mariam C Recuenco
- Department of Chemistry, Graduate School of Science, Kobe University, Kobe, Hyogo, Japan
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18
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Dihydrolipoic acid reduces cytochrome b561 proteins. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2012; 42:159-68. [DOI: 10.1007/s00249-012-0812-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 03/22/2012] [Accepted: 03/27/2012] [Indexed: 12/11/2022]
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19
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Cenacchi L, Busch M, Schleidt PG, Müller FG, Stumpp TVM, Mäntele W, Trost P, Lancaster CRD. Heterologous production and characterisation of two distinct dihaem-containing membrane integral cytochrome b(561) enzymes from Arabidopsis thaliana in Pichia pastoris and Escherichia coli cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:679-88. [PMID: 22085541 DOI: 10.1016/j.bbamem.2011.10.030] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Revised: 10/29/2011] [Accepted: 10/31/2011] [Indexed: 01/07/2023]
Abstract
Cytochrome (cyt) b(561) proteins are dihaem-containing membrane proteins, belonging to the CYBASC (cytochrome-b(561)-ascorbate-reducible) family, and are proposed to be involved in ascorbate recycling and/or the facilitation of iron absorption. Here, we present the heterologous production of two cyt b(561) paralogs from Arabidopsis thaliana (Acytb(561)-A, Acytb(561)-B) in Escherichia coli and Pichia pastoris, their purification, and initial characterisation. Spectra indicated that Acytb(561)-A resembles the best characterised member of the CYBASC family, the cytochrome b(561) from adrenomedullary chromaffin vesicles, and that Acytb(561)-B is atypical compared to other CYBASC proteins. Haem oxidation-reduction midpoint potential (E(M)) values were found to be fully consistent with ascorbate oxidation activities and Fe(3+)-chelates reductase activities. The ascorbate dependent reduction and protein stability of both paralogs were found to be sensitive to alkaline pH values as reported for the cytochrome b(561) from chromaffin vesicles. For both paralogs, ascorbate-dependent reduction was inhibited and the low-potential haem E(M) values were affected significantly by incubation with diethyl pyrocarbonate (DEPC) in the absence of ascorbate. Modification with DEPC in the presence of ascorbate left the haem E(M) values unaltered compared to the unmodified proteins. However, ascorbate reduction was inhibited. We concluded that the ascorbate-binding site is located near the low-potential haem with the Fe(3+)-chelates reduction-site close to the high-potential haem. Furthermore, inhibition of ascorbate oxidation by DEPC treatment occurs not only by lowering the haem E(M) values but also by an additional modification affecting ascorbate binding and/or electron transfer. Analytical gel filtration experiments suggest that both cyt b(561) paralogs exist as homodimers.
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Affiliation(s)
- Lucia Cenacchi
- Max Planck Institute of Biophysics, Department of Molecular Membrane Biology, Frankfurt, Germany
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20
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Abstract
Iron utilization by bacteria in aerobic environments involves uptake as a ferric chelate from the environment, followed by reduction to the ferrous form. Ferric iron reduction is poorly understood in most bacterial species. Here, we identified Bradyrhizobium japonicum frcB (bll3557) as a gene adjacent to, and coregulated with, the pyoR gene (blr3555) encoding the outer membrane receptor for transport of a ferric pyoverdine. FrcB is a membrane-bound, diheme protein, characteristic of eukaryotic ferric reductases. Heme was essential for FrcB stability, as were conserved histidine residues in the protein that likely coordinate the heme moieties. Expression of the frcB gene in Escherichia coli conferred ferric reductase activity on those cells. Furthermore, reduced heme in purified FrcB was oxidized by ferric iron in vitro. B. japonicum cells showed inducible ferric reductase activity in iron-limited cells that was diminished in an frcB mutant. Steady-state levels of frcB mRNA were strongly induced under iron-limiting conditions, but transcript levels were low and unresponsive to iron in an irr mutant lacking the global iron response transcriptional regulator Irr. Thus, Irr positively controls the frcB gene. FrcB belongs to a family of previously uncharacterized proteins found in many proteobacteria and some cyanobacteria. This suggests that membrane-bound, heme-containing ferric reductase proteins are not confined to eukaryotes but may be common in bacteria.
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Mikami Y, Saito A, Miwa E, Higuchi K. Allocation of Fe and ferric chelate reductase activities in mesophyll cells of barley and sorghum under Fe-deficient conditions. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2011; 49:513-9. [PMID: 21288731 DOI: 10.1016/j.plaphy.2011.01.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Accepted: 01/06/2011] [Indexed: 05/09/2023]
Abstract
Although the photosynthetic apparatus requires large amounts of Fe, the adaptive mechanisms of mesophyll cells for Fe acquisition under Fe-deficient conditions are unknown. Barley and sorghum, which are tolerant and susceptible to Fe deficiency, respectively, have similar Fe and chlorophyll contents in their leaves. However, the Fe-deficient barley photosynthetic apparatus was functional while that of sorghum was not. We show that barley preferentially allocates Fe to thylakoid membranes under Fe-deficient conditions. On the other hand, in sorghum, the proportion of leaf Fe allocated to thylakoids was not altered by Fe deficiency. The relationship between the maintenance of photosynthesis and light-dependent ferric chelate reductase activity on plasma membranes and chloroplast envelopes is also discussed.
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Affiliation(s)
- Yuichiro Mikami
- Laboratory of Plant Production Chemistry, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo 156-8502, Japan
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22
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Axial ligation of the high-potential heme center in an Arabidopsis
cytochrome b
561. FEBS Lett 2011; 585:545-8. [DOI: 10.1016/j.febslet.2011.01.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Revised: 12/21/2010] [Accepted: 01/04/2011] [Indexed: 11/19/2022]
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Glanfield A, McManus DP, Smyth DJ, Lovas EM, Loukas A, Gobert GN, Jones MK. A cytochrome b561 with ferric reductase activity from the parasitic blood fluke, Schistosoma japonicum. PLoS Negl Trop Dis 2010; 4:e884. [PMID: 21103361 PMCID: PMC2982821 DOI: 10.1371/journal.pntd.0000884] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Accepted: 10/18/2010] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND Iron has an integral role in numerous cellular reactions and is required by virtually all organisms. In physiological conditions, iron is abundant in a largely insoluble ferric state. Ferric reductases are an essential component of iron uptake by cells, reducing iron to the soluble ferrous form. Cytochromes b561 (cyts-b561) are a family of ascorbate reducing transmembrane proteins found in most eukaryotic cells. The identification of the ferric reductase duodenal cytochrome b (dcytb) and recent observations that other cyts-b561 may be involved in iron metabolism have opened novel perspectives for elucidating their physiological function. METHODOLOGY/PRINCIPAL FINDINGS Here we have identified a new member of the cytochrome b561 (Sjcytb561) family in the pathogenic blood fluke Schistosoma japonicum that localises to the outer surface of this parasitic trematode. Heterologous expression of recombinant Sjcyt-b561 in a Saccharomyces cerevisiae mutant strain that lacks plasma membrane ferrireductase activity demonstrated that the molecule could rescue ferric reductase activity in the yeast. SIGNIFICANCE/CONCLUSIONS This finding of a new member of the cytochrome b561 family further supports the notion that a ferric reductase function is likely for other members of this protein family. Additionally, the localisation of Sjcytb561 in the surface epithelium of these blood-dwelling schistosomes contributes further to our knowledge concerning nutrient acquisition in these parasites and may provide novel targets for therapeutic intervention.
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Affiliation(s)
- Amber Glanfield
- Queensland Institute of Medical Research, Herston, Queensland, Australia
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Bérczi A, Desmet F, Van Doorslaer S, Asard H. Spectral characterization of the recombinant mouse tumor suppressor 101F6 protein. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2009; 39:1129-42. [PMID: 19943161 DOI: 10.1007/s00249-009-0564-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Revised: 10/29/2009] [Accepted: 11/05/2009] [Indexed: 10/20/2022]
Abstract
Tumor suppressor protein 101F6, a gene product of the 3p21.3 (human) and 9F1 (mouse) chromosomal region, has recently been identified as a member of the cytochrome b561 (Cyt-b561) protein family by sequence homology. The His(6)-tagged recombinant mouse tumor suppressor Cyt-b561 protein (TSCytb) was recently expressed in yeast and purified, and the ascorbate reducibility was determined. TSCytb is auto-oxidizable and has two distinct heme b centers with redox potentials of approximately 40 and approximately 140 mV. Its split alpha-band in the dithionite-reduced spectrum at both 295 and 77 K is well resolved, and the separation between the two alpha-peaks is approximately 7 nm (approximately 222 cm(-1)). Singular value decomposition analysis of the split alpha-band in the ascorbate-reduced spectra revealed the presence of two major spectral components, each of them with split alpha-band but with different peak separations (6 and 8 nm). Similar minor differences in peak separation were obtained when the split alpha-bands in ascorbate-reduced difference spectra at low (<1 mM) and high (>10 mM) ascorbate concentrations were analysed. According to low-temperature electron paramagnetic resonance (EPR) spectroscopy, the two heme b centers are in the low-spin ferric state with maximum principal g values of 3.61 and 2.96, respectively. These values differ from the ones observed for other members of the Cyt-b561 family. According to resonance Raman spectroscopy, the porphyrin rings are in a relaxed state. The spectroscopic results are only partially in agreement with those obtained earlier for the native chromaffin granule Cyt-b561.
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Affiliation(s)
- Alajos Bérczi
- Institute of Biophysics, Biological Research Center, Hungarian Academy of Sciences, Temesvári krt. 62, P.O. Box 521, 6701, Szeged, Hungary.
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Nakanishi N, Rahman MM, Sakamoto Y, Takigami T, Kobayashi K, Hori H, Hase T, Park SY, Tsubaki M. Importance of the conserved lysine 83 residue of Zea mays cytochrome b(561) for ascorbate-specific transmembrane electron transfer as revealed by site-directed mutagenesis studies. Biochemistry 2009; 48:10665-78. [PMID: 19803484 DOI: 10.1021/bi9010682] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Cytochromes b(561), a novel class of transmembrane electron transport proteins residing in a large variety of eukaryotic cells, have a number of common structural features including six hydrophobic transmembrane alpha-helices and two heme ligation sites. We found that recombinant Zea mays cytochrome b(561) obtained by a heterologous expression system using yeast Pichia pastoris cells could utilize the ascorbate/mondehydroascorbate radical as a physiological electron donor/acceptor. We found further that a concerted proton/electron transfer mechanism might be operative in Z. mays cytochrome b(561) as well upon the electron acceptance from ascorbate to the cytosolic heme center. The well-conserved Lys(83) residue in a cytosolic loop was found to have a very important role(s) for the binding of ascorbate and the succeeding electron transfer via electrostatic interactions based on the analyses of three site-specific mutants, K83A, K83E, and K83D. Further, unusual behavior of the K83A mutant in pulse radiolysis experiments indicated that Lys(83) might also be responsible for the intramolecular electron transfer to the intravesicular heme. On the other hand, pulse radiolysis experiments on two site-specific mutants, S118A and W122A, for the well-conserved residues in the putative monodehydroascorbate radical binding site showed that their electron transfer activities to the monodehydroascorbate radical were very similar to those of the wild-type protein, indicating that Ser(118) and Trp(122) do not have major roles for the redox events on the intravesicular side.
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Affiliation(s)
- Nobuyuki Nakanishi
- Department of Molecular Science and Material Engineering, Graduate School of Science and Technology, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, Hyogo 657-8501, Japan
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26
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Butzin NC, Owen HA, Collins MLP. A new system for heterologous expression of membrane proteins: Rhodospirillum rubrum. Protein Expr Purif 2009; 70:88-94. [PMID: 19887111 DOI: 10.1016/j.pep.2009.10.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Revised: 10/20/2009] [Accepted: 10/23/2009] [Indexed: 11/29/2022]
Abstract
Heterologous expression of membrane proteins has met with only limited success. This work presents a new host/vector system for the production of heterologous membrane proteins based on a mutant of the facultatively phototrophic bacterium Rhodospirillum rubrum. Under certain growth conditions, R. rubrum forms an intracytoplasmic membrane (ICM) that houses the photosynthetic apparatus, the structural proteins of which are encoded by puhA and pufBALM. The mutant R. rubrum H2, which was constructed by allelic exchange deleting puhA and pufBALM, does not form ICM. This strain was used as a host for a plasmid expressing the Pseudomonas aeruginosa membrane protein MscL from the Rhodobacter capsulatus puc promoter. ICM was formed in the H2 strain producing MscL but not in the vector control strain. These results suggest that a heterologous membrane protein stimulates ICM formation in R. rubrum and indicate that the capacity to form an ICM that can accommodate heterologous proteins makes R. rubrum a host that will be useful for membrane protein production. P. aeruginosa MscL, which forms inclusion bodies when produced in Escherichia coli, was expressed in R. rubrum H2 and purified from membranes with a yield of 22.8-23.4 mg/L culture (5.53-5.60 mg/g cell paste). Additionally Streptomyces lividans KcsA and P. aeruginosa CycB were produced and purified from R. rubrum H2 with yields of 13.7-14.4 mg/L culture (2.19-2.55 mg/g cell paste) and 6.6-7.4 mg/L culture (1.1-1.2mg/g cell paste), respectively.
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Affiliation(s)
- Nicholas C Butzin
- Department of Biological Sciences, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, WI 53201, USA
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Harrington JM, Crumbliss AL. The redox hypothesis in siderophore-mediated iron uptake. Biometals 2009; 22:679-89. [DOI: 10.1007/s10534-009-9233-4] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Accepted: 03/23/2009] [Indexed: 12/27/2022]
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Hunting for low abundant redox proteins in plant plasma membranes. J Proteomics 2009; 72:475-83. [DOI: 10.1016/j.jprot.2008.11.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2008] [Revised: 10/27/2008] [Accepted: 11/01/2008] [Indexed: 01/17/2023]
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Oakhill JS, Marritt SJ, Gareta EG, Cammack R, McKie AT. Functional characterization of human duodenal cytochrome b (Cybrd1): Redox properties in relation to iron and ascorbate metabolism. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:260-8. [DOI: 10.1016/j.bbabio.2007.12.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2007] [Revised: 12/11/2007] [Accepted: 12/12/2007] [Indexed: 10/22/2022]
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Furt F, Lefebvre B, Cullimore J, Bessoule JJ, Mongrand S. Plant lipid rafts: fluctuat nec mergitur. PLANT SIGNALING & BEHAVIOR 2007; 2:508-11. [PMID: 19704542 PMCID: PMC2634352 DOI: 10.4161/psb.2.6.4636] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2007] [Accepted: 06/27/2007] [Indexed: 05/20/2023]
Abstract
Lipid rafts in plasma membranes are hypothesized to play key roles in many cellular processes including signal transduction, membrane trafficking and entry of pathogens. We recently documented the biochemical characterization of lipid rafts, isolated as detergent-insoluble membranes, from Medicago truncatula root plasma membranes. We evidenced that the plant-specific lipid steryl-conjugates are among the main lipids of rafts together with free sterols and sphingolipids. An extensive proteomic analysis showed the presence of a specific set of proteins common to other lipid rafts, plus the presence of a redox system around a cytochrome b(561) not previously identified in lipid rafts of either plants or animals. Here, we discuss the similarities and differences between the lipids and proteins of plant and animal lipid rafts. Moreover we describe the potential biochemical functioning of the M. truncatula root lipid raft redox proteins and question whether they may play a physiological role in legume-symbiont interactions.
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Affiliation(s)
- Fabienne Furt
- Laboratoire de Biogenèse Membranaire; Université Victor Segalen; Bordeaux, France
| | - Benoit Lefebvre
- Laboratoire des Interactions Plantes Micro-organismes; Castanet-Tolosan, France
| | - Julie Cullimore
- Laboratoire des Interactions Plantes Micro-organismes; Castanet-Tolosan, France
| | | | - Sébastien Mongrand
- Laboratoire de Biogenèse Membranaire; Université Victor Segalen; Bordeaux, France
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Kamensky Y, Liu W, Tsai AL, Kulmacz RJ, Palmer G. Axial ligation and stoichiometry of heme centers in adrenal cytochrome b561. Biochemistry 2007; 46:8647-58. [PMID: 17602662 PMCID: PMC2551744 DOI: 10.1021/bi700054g] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Cytochrome (cyt) b561 transports electrons across the membrane of chromaffin granules (CG) present in the adrenal medulla, supporting the biosynthesis of norepinephrine in the CG matrix. We have conducted a detailed characterization of cyt b561 using electron paramagnetic resonance (EPR) and optical spectroscopy on the wild-type and mutant forms of the cytochrome expressed in insect cells. The gz = 3.7 (low-potential heme) and gz = 3.1 (high-potential heme) signals were found to represent the only two authentic hemes of cyt b561; models that propose smaller or greater amounts of heme can be ruled out. We identified the axial ligands to hemes in cyt b561 by mutating four conserved histidines (His54 and His122 at the matrix-side heme center and His88 and His161 at the cytoplasmic-side heme center), thus confirming earlier structural models. Single mutations of any of these histidines produced a constellation of spectroscopic changes that involve not one but both heme centers. We hypothesize that the two hemes and their axial ligands in cyt b561 are integral parts of a structural unit that we term the "kernel". Histidine to glutamine substitutions in the cytoplasmic-side heme center but not in the matrix-side heme center led to the retention of a small fraction of the low-potential heme with gz = 3.7. We provisionally assign the low-potential heme to the matrix side of the membrane; this arrangement suggests that the membrane potential modulates electron transport across the CG membrane.
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Affiliation(s)
- Yury Kamensky
- Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77251, USA.
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