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Dobrzyńska K, Pérez-González A, Echavarri-Erasun C, Coroian D, Salinero-Lanzarote A, Veldhuizen M, Dean DR, Burén S, Rubio LM. Nitrogenase cofactor biosynthesis using proteins produced in mitochondria of Saccharomyces cerevisiae. mBio 2024; 15:e0308823. [PMID: 38126768 PMCID: PMC10865832 DOI: 10.1128/mbio.03088-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 11/20/2023] [Indexed: 12/23/2023] Open
Abstract
Biological nitrogen fixation, the conversion of inert N2 to metabolically tractable NH3, is only performed by certain microorganisms called diazotrophs and is catalyzed by the nitrogenases. A [7Fe-9S-C-Mo-R-homocitrate]-cofactor, designated FeMo-co, provides the catalytic site for N2 reduction in the Mo-dependent nitrogenase. Thus, achieving FeMo-co formation in model eukaryotic organisms, such as Saccharomyces cerevisiae, represents an important milestone toward endowing them with a capacity for Mo-dependent biological nitrogen fixation. A central player in FeMo-co assembly is the scaffold protein NifEN upon which processing of NifB-co, an [8Fe-9S-C] precursor produced by NifB, occurs. Prior work established that NifB-co can be produced in S. cerevisiae mitochondria. In the present work, a library of nifEN genes from diverse diazotrophs was expressed in S. cerevisiae, targeted to mitochondria, and surveyed for their ability to produce soluble NifEN protein complexes. Many such NifEN variants supported FeMo-co formation when heterologously produced in the diazotroph A. vinelandii. However, only three of them accumulated in soluble forms in mitochondria of aerobically cultured S. cerevisiae. Of these, two variants were active in the in vitro FeMo-co synthesis assay. NifEN, NifB, and NifH proteins from different species, all of them produced in and purified from S. cerevisiae mitochondria, were combined to establish successful FeMo-co biosynthetic pathways. These findings demonstrate that combining diverse interspecies nitrogenase FeMo-co assembly components could be an effective and, perhaps, the only approach to achieve and optimize nitrogen fixation in a eukaryotic organism.IMPORTANCEBiological nitrogen fixation, the conversion of inert N2 to metabolically usable NH3, is a process exclusive to diazotrophic microorganisms and relies on the activity of nitrogenases. The assembly of the nitrogenase [7Fe-9S-C-Mo-R-homocitrate]-cofactor (FeMo-co) in a eukaryotic cell is a pivotal milestone that will pave the way to engineer cereals with nitrogen fixing capabilities and therefore independent of nitrogen fertilizers. In this study, we identified NifEN protein complexes that were functional in the model eukaryotic organism Saccharomyces cerevisiae. NifEN is an essential component of the FeMo-co biosynthesis pathway. Furthermore, the FeMo-co biosynthetic pathway was recapitulated in vitro using only proteins expressed in S. cerevisiae. FeMo-co biosynthesis was achieved by combining nitrogenase FeMo-co assembly components from different species, a promising strategy to engineer nitrogen fixation in eukaryotic organisms.
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Affiliation(s)
- Katarzyna Dobrzyńska
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA/CSIC), Pozuelo de Alarcón, Spain
- Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaría y de Biosistemas, Universidad Politécnica de Madrid, Madrid, Spain
| | | | - Carlos Echavarri-Erasun
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA/CSIC), Pozuelo de Alarcón, Spain
- Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaría y de Biosistemas, Universidad Politécnica de Madrid, Madrid, Spain
| | - Diana Coroian
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA/CSIC), Pozuelo de Alarcón, Spain
| | - Alvaro Salinero-Lanzarote
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA/CSIC), Pozuelo de Alarcón, Spain
| | - Marcel Veldhuizen
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA/CSIC), Pozuelo de Alarcón, Spain
| | - Dennis R. Dean
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, USA
| | - Stefan Burén
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA/CSIC), Pozuelo de Alarcón, Spain
- Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaría y de Biosistemas, Universidad Politécnica de Madrid, Madrid, Spain
| | - Luis M. Rubio
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA/CSIC), Pozuelo de Alarcón, Spain
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2
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Martin Del Campo JS, Rigsbee J, Bueno Batista M, Mus F, Rubio LM, Einsle O, Peters JW, Dixon R, Dean DR, Dos Santos PC. Overview of physiological, biochemical, and regulatory aspects of nitrogen fixation in Azotobacter vinelandii. Crit Rev Biochem Mol Biol 2023; 57:492-538. [PMID: 36877487 DOI: 10.1080/10409238.2023.2181309] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
Abstract
Understanding how Nature accomplishes the reduction of inert nitrogen gas to form metabolically tractable ammonia at ambient temperature and pressure has challenged scientists for more than a century. Such an understanding is a key aspect toward accomplishing the transfer of the genetic determinants of biological nitrogen fixation to crop plants as well as for the development of improved synthetic catalysts based on the biological mechanism. Over the past 30 years, the free-living nitrogen-fixing bacterium Azotobacter vinelandii emerged as a preferred model organism for mechanistic, structural, genetic, and physiological studies aimed at understanding biological nitrogen fixation. This review provides a contemporary overview of these studies and places them within the context of their historical development.
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Affiliation(s)
| | - Jack Rigsbee
- Department of Chemistry, Wake Forest University, Winston-Salem, NC, USA
| | | | - Florence Mus
- Institute of Biological Chemistry, Washington State University, Pullman, WA, USA
| | - Luis M Rubio
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA/CSIC), Pozuelo de Alarcón, Spain
| | - Oliver Einsle
- Department of Biochemistry, University of Freiburg, Freiburg, Germany
| | - John W Peters
- Institute of Biological Chemistry, Washington State University, Pullman, WA, USA
| | - Ray Dixon
- Department of Molecular Microbiology, John Innes Centre, Norwich, UK
| | - Dennis R Dean
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, USA
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3
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Decamps L, Rice DB, DeBeer S. An Fe 6 C Core in All Nitrogenase Cofactors. Angew Chem Int Ed Engl 2022; 61:e202209190. [PMID: 35975943 PMCID: PMC9826452 DOI: 10.1002/anie.202209190] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Indexed: 01/11/2023]
Abstract
The biological process of dinitrogen reduction to ammonium occurs at the cofactors of nitrogenases, the only enzymes that catalyze this challenging chemical reaction. Three types of nitrogenases have been described, named according to the heterometal in their cofactor: molybdenum, vanadium or iron nitrogenases. Spectroscopic and structural characterization allowed the unambiguous identification of the cofactors of molybdenum and vanadium nitrogenases and revealed a central μ6 -carbide in both of them. Although genetic studies suggested that the cofactor of the iron nitrogenase contains a similar Fe6 C core, this has not been experimentally demonstrated. Here we report Valence-to-Core X-ray Emission Spectroscopy providing experimental evidence that this cofactor contains a carbide, thereby making the Fe6 C core a feature of all nitrogenase cofactors.
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Affiliation(s)
- Laure Decamps
- Department of Inorganic SpectroscopyMax Planck Institute for Chemical Energy ConversionStiftstrasse 34–3645470Mülheim an derRuhrGermany
| | - Derek B. Rice
- Department of Inorganic SpectroscopyMax Planck Institute for Chemical Energy ConversionStiftstrasse 34–3645470Mülheim an derRuhrGermany
| | - Serena DeBeer
- Department of Inorganic SpectroscopyMax Planck Institute for Chemical Energy ConversionStiftstrasse 34–3645470Mülheim an derRuhrGermany
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4
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He W, Burén S, Baysal C, Jiang X, Capell T, Christou P, Rubio LM. Nitrogenase Cofactor Maturase NifB Isolated from Transgenic Rice is Active in FeMo-co Synthesis. ACS Synth Biol 2022; 11:3028-3036. [PMID: 35998307 PMCID: PMC9486962 DOI: 10.1021/acssynbio.2c00194] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The engineering of nitrogen fixation in plants requires assembly of an active prokaryotic nitrogenase complex, which is yet to be achieved. Nitrogenase biogenesis relies on NifB, which catalyzes the formation of the [8Fe-9S-C] metal cluster NifB-co. This is the first committed step in the biosynthesis of the iron-molybdenum cofactor (FeMo-co) found at the nitrogenase active site. The production of NifB in plants is challenging because this protein is often insoluble in eukaryotic cells, and its [Fe-S] clusters are extremely unstable and sensitive to O2. As a first step to address this challenge, we generated transgenic rice plants expressing NifB from the Archaea Methanocaldococcus infernus and Methanothermobacter thermautotrophicus. The recombinant proteins were targeted to the mitochondria to limit exposure to O2 and to have access to essential [4Fe-4S] clusters required for NifB-co biosynthesis. M. infernus and M. thermautotrophicus NifB accumulated as soluble proteins in planta, and the purified proteins were functional in the in vitro FeMo-co synthesis assay. We thus report NifB protein expression and purification from an engineered staple crop, representing a first step in the biosynthesis of a functional NifDK complex, as required for independent biological nitrogen fixation in cereals.
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Affiliation(s)
- Wenshu He
- Department
of Plant Production and Forestry Science, University of Lleida-Agrotecnio CERCA Center, Av. Alcalde Rovira Roure, 191, 25198 Lleida, Spain
| | - Stefan Burén
- Centro
de Biotecnología y Genómica de Plantas, Universidad
Politécnica de Madrid (UPM), Instituto
Nacional de Investigación y Tecnología Agraria y Alimentaria
(INIA), Campus Montegancedo
UPM, Pozuelo de Alarcón, 28223 , Madrid, Spain,Departamento
de Biotecnología-Biología Vegetal, Escuela Técnica
Superior de Ingeniería Agronómica, Alimentaria y de
Biosistemas, Universidad Politécnica
de Madrid, 28040 Madrid, Spain
| | - Can Baysal
- Department
of Plant Production and Forestry Science, University of Lleida-Agrotecnio CERCA Center, Av. Alcalde Rovira Roure, 191, 25198 Lleida, Spain
| | - Xi Jiang
- Centro
de Biotecnología y Genómica de Plantas, Universidad
Politécnica de Madrid (UPM), Instituto
Nacional de Investigación y Tecnología Agraria y Alimentaria
(INIA), Campus Montegancedo
UPM, Pozuelo de Alarcón, 28223 , Madrid, Spain,Departamento
de Biotecnología-Biología Vegetal, Escuela Técnica
Superior de Ingeniería Agronómica, Alimentaria y de
Biosistemas, Universidad Politécnica
de Madrid, 28040 Madrid, Spain
| | - Teresa Capell
- Department
of Plant Production and Forestry Science, University of Lleida-Agrotecnio CERCA Center, Av. Alcalde Rovira Roure, 191, 25198 Lleida, Spain
| | - Paul Christou
- Department
of Plant Production and Forestry Science, University of Lleida-Agrotecnio CERCA Center, Av. Alcalde Rovira Roure, 191, 25198 Lleida, Spain,ICREA,
Catalan Institute for Research and Advanced Studies, Passeig Lluís Companys 23, 08010 Barcelona, Spain,
| | - Luis M. Rubio
- Centro
de Biotecnología y Genómica de Plantas, Universidad
Politécnica de Madrid (UPM), Instituto
Nacional de Investigación y Tecnología Agraria y Alimentaria
(INIA), Campus Montegancedo
UPM, Pozuelo de Alarcón, 28223 , Madrid, Spain,Departamento
de Biotecnología-Biología Vegetal, Escuela Técnica
Superior de Ingeniería Agronómica, Alimentaria y de
Biosistemas, Universidad Politécnica
de Madrid, 28040 Madrid, Spain,
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5
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Decamps L, Rice D, DeBeer S. An Fe6C Core in All Nitrogenase Cofactors. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202209190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Laure Decamps
- Max-Planck-Institute for Chemical Energy Conversion: Max-Planck-Institut fur chemische Energiekonversion Inorganic Spectroscopy GERMANY
| | - Derek Rice
- Max-Planck-Institute for Chemical Energy Conversion: Max-Planck-Institut fur chemische Energiekonversion Inorganic Spectroscopy GERMANY
| | - Serena DeBeer
- MPI CEC Molecular Theory and Spectroscopy Stidtstr. 34-36 45470 Muelheim an der Ruhr GERMANY
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Jiang X, Coroian D, Barahona E, Echavarri-Erasun C, Castellanos-Rueda R, Eseverri Á, Aznar-Moreno JA, Burén S, Rubio LM. Functional Nitrogenase Cofactor Maturase NifB in Mitochondria and Chloroplasts of Nicotiana benthamiana. mBio 2022; 13:e0026822. [PMID: 35695456 PMCID: PMC9239050 DOI: 10.1128/mbio.00268-22] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 05/16/2022] [Indexed: 11/20/2022] Open
Abstract
Engineering plants to synthesize nitrogenase and assimilate atmospheric N2 will reduce crop dependency on industrial N fertilizers. This technology can be achieved by expressing prokaryotic nitrogen fixation gene products for the assembly of a functional nitrogenase in plants. NifB is a critical nitrogenase component since it catalyzes the first committed step in the biosynthesis of all types of nitrogenase active-site cofactors. Here, we used a library of 30 distinct nifB sequences originating from different phyla and ecological niches to restore diazotrophic growth of an Azotobacter vinelandii nifB mutant. Twenty of these variants rescued the nifB mutant phenotype despite their phylogenetic distance to A. vinelandii. Because multiple protein interactions are required in the iron-molybdenum cofactor (FeMo-co) biosynthetic pathway, the maturation of nitrogenase in a heterologous host can be divided in independent modules containing interacting proteins that function together to produce a specific intermediate. Therefore, nifB functional modules composed of a nifB variant, together with the A. vinelandii NifS and NifU proteins (for biosynthesis of NifB [Fe4S4] clusters) and the FdxN ferredoxin (for NifB function), were expressed in Nicotiana benthamiana chloroplasts and mitochondria. Three archaeal NifB proteins accumulated at high levels in soluble fractions of chloroplasts (Methanosarcina acetivorans and Methanocaldococcus infernus) or mitochondria (M. infernus and Methanothermobacter thermautotrophicus). These NifB proteins were shown to accept [Fe4S4] clusters from NifU and were functional in FeMo-co synthesis in vitro. The accumulation of significant levels of soluble and functional NifB proteins in chloroplasts and mitochondria is critical to engineering biological nitrogen fixation in plants. IMPORTANCE Biological nitrogen fixation is the conversion of inert atmospheric dinitrogen gas into nitrogen-reactive ammonia, a reaction catalyzed by the nitrogenase enzyme of diazotrophic bacteria and archaea. Because plants cannot fix their own nitrogen, introducing functional nitrogenase in cereals and other crop plants would reduce our strong dependency on N fertilizers. NifB is required for the biosynthesis of the active site cofactors of all nitrogenases, which arguably makes it the most important protein in global nitrogen fixation. NifB functionality is therefore a requisite to engineer a plant nitrogenase. The expression of nifB genes from a wide range of prokaryotes into the model diazotroph Azotobacter vinelandii shows a surprising level of genetic complementation suggestive of plasticity in the nitrogenase biosynthetic pathway. In addition, we obtained NifB proteins from both mitochondria and chloroplasts of tobacco that are functional in vitro after reconstitution by providing [Fe4S4] clusters from NifU, paving the way to nitrogenase cofactor biosynthesis in plants.
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Affiliation(s)
- Xi Jiang
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, Madrid, Spain
- Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Madrid, Spain
| | - Diana Coroian
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, Madrid, Spain
| | - Emma Barahona
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, Madrid, Spain
| | - Carlos Echavarri-Erasun
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, Madrid, Spain
- Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Madrid, Spain
| | - Rocío Castellanos-Rueda
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, Madrid, Spain
| | - Álvaro Eseverri
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, Madrid, Spain
| | - Jose A. Aznar-Moreno
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, Madrid, Spain
| | - Stefan Burén
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, Madrid, Spain
- Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Madrid, Spain
| | - Luis M. Rubio
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, Madrid, Spain
- Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Madrid, Spain
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7
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Hunyady J. The Result of Vitamin C Treatment of Patients with Cancer: Conditions Influencing the Effectiveness. Int J Mol Sci 2022; 23:ijms23084380. [PMID: 35457200 PMCID: PMC9030840 DOI: 10.3390/ijms23084380] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 04/08/2022] [Accepted: 04/10/2022] [Indexed: 11/16/2022] Open
Abstract
Vitamin C (ascorbic acid, AA) is a weak sugar acid structurally related to glucose. All known physiological and biochemical functions of AA are due to its action as an electron donor. Ascorbate readily undergoes pH-dependent autoxidation creating hydrogen peroxide (H2O2). In vitro evidence suggests that vitamin C functions at low concentrations as an antioxidant while high concentration is pro-oxidant. Thus, both characters of AA might be translated into clinical benefits. In vitro obtained results and murine experiments consequently prove the cytotoxic effect of AA on cancer cells, but current clinical evidence for high-dose intravenous (i.v.) vitamin C's therapeutic effect is ambiguous. The difference might be caused by the missing knowledge of AA's actions. In the literature, there are many publications regarding vitamin C and cancer. Review papers of systematic analysis of human interventional and observational studies assessing i.v. AA for cancer patients' use helps the overview of the extensive literature. Based on the results of four review articles and the Cancer Information Summary of the National Cancer Institute's results, we analyzed 20 publications related to high-dose intravenous vitamin C therapy (HAAT). The analyzed results indicate that HAAT might be a useful cancer-treating tool in certain circumstances. The AA's cytotoxic effect is hypoxia-induced factor dependent. It impacts only the anoxic cells, using the Warburg metabolism. It prevents tumor growth. Accordingly, discontinuation of treatment leads to repeated expansion of the tumor. We believe that the clinical use of HAAT in cancer treatment should be reassessed. The accumulation of more study results on HAAT is desperately needed.
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Affiliation(s)
- János Hunyady
- Department of Dermatology, Medical Faculty, University of Debrecen, 4032 Debrecen, Hungary
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8
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Postbiosynthetic modification of a precursor to the nitrogenase iron-molybdenum cofactor. Proc Natl Acad Sci U S A 2021; 118:2015361118. [PMID: 33836573 DOI: 10.1073/pnas.2015361118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nitrogenases utilize Fe-S clusters to reduce N2 to NH3 The large number of Fe sites in their catalytic cofactors has hampered spectroscopic investigations into their electronic structures, mechanisms, and biosyntheses. To facilitate their spectroscopic analysis, we are developing methods for incorporating 57Fe into specific sites of nitrogenase cofactors, and we report herein site-selective 57Fe labeling of the L-cluster-a carbide-containing, [Fe8S9C] precursor to the Mo nitrogenase catalytic cofactor. Treatment of the isolated L-cluster with the chelator ethylenediaminetetraacetate followed by reconstitution with 57Fe2+ results in 57Fe labeling of the terminal Fe sites in high yield and with high selectivity. This protocol enables the generation of L-cluster samples in which either the two terminal or the six belt Fe sites are selectively labeled with 57Fe. Mössbauer spectroscopic analysis of these samples bound to the nitrogenase maturase Azotobacter vinelandii NifX reveals differences in the primary coordination sphere of the terminal Fe sites and that one of the terminal sites of the L-cluster binds to H35 of Av NifX. This work provides molecular-level insights into the electronic structure and biosynthesis of the L-cluster and introduces postbiosynthetic modification as a promising strategy for studies of nitrogenase cofactors.
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9
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Jiang X, Payá-Tormo L, Coroian D, García-Rubio I, Castellanos-Rueda R, Eseverri Á, López-Torrejón G, Burén S, Rubio LM. Exploiting genetic diversity and gene synthesis to identify superior nitrogenase NifH protein variants to engineer N 2-fixation in plants. Commun Biol 2021; 4:4. [PMID: 33398015 PMCID: PMC7782807 DOI: 10.1038/s42003-020-01536-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 11/25/2020] [Indexed: 01/01/2023] Open
Abstract
Engineering nitrogen fixation in eukaryotes requires high expression of functional nitrogenase structural proteins, a goal that has not yet been achieved. Here we build a knowledge-based library containing 32 nitrogenase nifH sequences from prokaryotes of diverse ecological niches and metabolic features and combine with rapid screening in tobacco to identify superior NifH variants for plant mitochondria expression. Three NifH variants outperform in tobacco mitochondria and are further tested in yeast. Hydrogenobacter thermophilus (Aquificae) NifH is isolated in large quantities from yeast mitochondria and fulfills NifH protein requirements for efficient N2 fixation, including electron transfer for substrate reduction, P-cluster maturation, and FeMo-co biosynthesis. H. thermophilus NifH expressed in tobacco leaves shows lower nitrogenase activity than that from yeast. However, transfer of [Fe4S4] clusters from NifU to NifH in vitro increases 10-fold the activity of the tobacco-isolated NifH, revealing that plant mitochondria [Fe-S] cluster availability constitutes a bottleneck to engineer plant nitrogenases.
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Affiliation(s)
- Xi Jiang
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, 28223, Madrid, Spain
- Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaría y de Biosistemas, Universidad Politécnica de Madrid, 28040, Madrid, Spain
| | - Lucía Payá-Tormo
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, 28223, Madrid, Spain
- Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaría y de Biosistemas, Universidad Politécnica de Madrid, 28040, Madrid, Spain
| | - Diana Coroian
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, 28223, Madrid, Spain
| | - Inés García-Rubio
- Centro Universitario de la Defensa, Ctra. de Huesca s/n, 50090, Zaragoza, Spain
| | - Rocío Castellanos-Rueda
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, 28223, Madrid, Spain
- Department of Biosystems Science and Engineering, ETH Zürich, 4058, Basel, Switzerland
| | - Álvaro Eseverri
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, 28223, Madrid, Spain
- Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaría y de Biosistemas, Universidad Politécnica de Madrid, 28040, Madrid, Spain
| | - Gema López-Torrejón
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, 28223, Madrid, Spain
- Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaría y de Biosistemas, Universidad Politécnica de Madrid, 28040, Madrid, Spain
| | - Stefan Burén
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, 28223, Madrid, Spain.
| | - Luis Manuel Rubio
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, 28223, Madrid, Spain.
- Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaría y de Biosistemas, Universidad Politécnica de Madrid, 28040, Madrid, Spain.
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10
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Burén S, Jiménez-Vicente E, Echavarri-Erasun C, Rubio LM. Biosynthesis of Nitrogenase Cofactors. Chem Rev 2020; 120:4921-4968. [PMID: 31975585 PMCID: PMC7318056 DOI: 10.1021/acs.chemrev.9b00489] [Citation(s) in RCA: 106] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Indexed: 12/30/2022]
Abstract
Nitrogenase harbors three distinct metal prosthetic groups that are required for its activity. The simplest one is a [4Fe-4S] cluster located at the Fe protein nitrogenase component. The MoFe protein component carries an [8Fe-7S] group called P-cluster and a [7Fe-9S-C-Mo-R-homocitrate] group called FeMo-co. Formation of nitrogenase metalloclusters requires the participation of the structural nitrogenase components and many accessory proteins, and occurs both in situ, for the P-cluster, and in external assembly sites for FeMo-co. The biosynthesis of FeMo-co is performed stepwise and involves molecular scaffolds, metallochaperones, radical chemistry, and novel and unique biosynthetic intermediates. This review provides a critical overview of discoveries on nitrogenase cofactor structure, function, and activity over the last four decades.
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Affiliation(s)
- Stefan Burén
- Centro
de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM), Instituto
Nacional de Investigación y Tecnología Agraria
y Alimentaria (INIA), Pozuelo de Alarcón, 28223 Madrid, Spain
| | - Emilio Jiménez-Vicente
- Department
of Biochemistry, Virginia Polytechnic Institute, Blacksburg, Virginia 24061, United States
| | - Carlos Echavarri-Erasun
- Centro
de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM), Instituto
Nacional de Investigación y Tecnología Agraria
y Alimentaria (INIA), Pozuelo de Alarcón, 28223 Madrid, Spain
| | - Luis M. Rubio
- Centro
de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM), Instituto
Nacional de Investigación y Tecnología Agraria
y Alimentaria (INIA), Pozuelo de Alarcón, 28223 Madrid, Spain
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11
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Abstract
Nitrogenase is the only enzyme capable of reducing N2 to NH3. This challenging reaction requires the coordinated transfer of multiple electrons from the reductase, Fe-protein, to the catalytic component, MoFe-protein, in an ATP-dependent fashion. In the last two decades, there have been significant advances in our understanding of how nitrogenase orchestrates electron transfer (ET) from the Fe-protein to the catalytic site of MoFe-protein and how energy from ATP hydrolysis transduces the ET processes. In this review, we summarize these advances, with focus on the structural and thermodynamic redox properties of nitrogenase component proteins and their complexes, as well as on new insights regarding the mechanism of ET reactions during catalysis and how they are coupled to ATP hydrolysis. We also discuss recently developed chemical, photochemical, and electrochemical methods for uncoupling substrate reduction from ATP hydrolysis, which may provide new avenues for studying the catalytic mechanism of nitrogenase.
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Affiliation(s)
- Hannah L Rutledge
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0340, United States
| | - F Akif Tezcan
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0340, United States
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12
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Van Stappen C, Decamps L, Cutsail GE, Bjornsson R, Henthorn JT, Birrell JA, DeBeer S. The Spectroscopy of Nitrogenases. Chem Rev 2020; 120:5005-5081. [PMID: 32237739 PMCID: PMC7318057 DOI: 10.1021/acs.chemrev.9b00650] [Citation(s) in RCA: 115] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Indexed: 01/08/2023]
Abstract
Nitrogenases are responsible for biological nitrogen fixation, a crucial step in the biogeochemical nitrogen cycle. These enzymes utilize a two-component protein system and a series of iron-sulfur clusters to perform this reaction, culminating at the FeMco active site (M = Mo, V, Fe), which is capable of binding and reducing N2 to 2NH3. In this review, we summarize how different spectroscopic approaches have shed light on various aspects of these enzymes, including their structure, mechanism, alternative reactivity, and maturation. Synthetic model chemistry and theory have also played significant roles in developing our present understanding of these systems and are discussed in the context of their contributions to interpreting the nature of nitrogenases. Despite years of significant progress, there is still much to be learned from these enzymes through spectroscopic means, and we highlight where further spectroscopic investigations are needed.
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Affiliation(s)
- Casey Van Stappen
- Max Planck Institute for
Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Laure Decamps
- Max Planck Institute for
Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - George E. Cutsail
- Max Planck Institute for
Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Ragnar Bjornsson
- Max Planck Institute for
Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Justin T. Henthorn
- Max Planck Institute for
Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - James A. Birrell
- Max Planck Institute for
Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Serena DeBeer
- Max Planck Institute for
Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
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13
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Rupnik K, Tanifuji K, Rettberg L, Ribbe MW, Hu Y, Hales BJ. Electron Paramagnetic Resonance and Magnetic Circular Dichroism Spectra of the Nitrogenase M Cluster Precursor Suggest Sulfur Migration upon Oxidation: A Proposal for Substrate and Inhibitor Binding. Chembiochem 2020; 21:1767-1772. [PMID: 31881119 PMCID: PMC7481019 DOI: 10.1002/cbic.201900681] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Indexed: 02/01/2023]
Abstract
The active site of the nitrogen-fixing enzyme Mo-nitrogenase is the M cluster ([MoFe7 S9 C⋅R-homocitrate]), also known as the FeMo cofactor or FeMoco. The biosynthesis of this highly complex metallocluster involves a series of proteins. Among them, NifB, a radical-SAM enzyme, is instrumental in the assembly of the L cluster ([Fe8 S9 C]), a precursor and all-iron core of the M cluster. In the absence of sulfite, NifB assembles a precursor form of the L cluster called the L* cluster ([Fe8 S8 C]), which lacks the final ninth sulfur. EPR and MCD spectroscopies are used to probe the electronic structures of the paramagnetic, oxidized forms of both the L and L* clusters, labeled LOx and [L*]Ox . This study shows that both LOx and [L*]Ox have nearly identical EPR and MCD spectra, thus suggesting that the two clusters have identical structures upon oxidation; in other words, a sulfur migrates away from LOx following oxidation, thereby rendering the cluster identical to [L*]Ox . It is proposed that a similar migration could occur to the M cluster upon oxidation, and that this is an instrumental part of both M cluster formation and nitrogenase substrate/inhibitor binding.
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Affiliation(s)
- Kresimir Rupnik
- Department of Chemistry, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Kazuki Tanifuji
- Department of Molecular Biology & Biochemistry, University of California, Irvine, Irvine, CA, 92697-3900, USA
| | - Lee Rettberg
- Department of Molecular Biology & Biochemistry, University of California, Irvine, Irvine, CA, 92697-3900, USA
| | - Markus W Ribbe
- Department of Molecular Biology & Biochemistry, University of California, Irvine, Irvine, CA, 92697-3900, USA
- Department of Chemistry, University of California, Irvine, Irvine, CA, 92697-2025, USA
| | - Yilin Hu
- Department of Molecular Biology & Biochemistry, University of California, Irvine, Irvine, CA, 92697-3900, USA
| | - Brian J Hales
- Department of Chemistry, Louisiana State University, Baton Rouge, LA, 70803, USA
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14
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Fajardo AS, Legrand P, Payá-Tormo LA, Martin L, Pellicer Martı Nez MT, Echavarri-Erasun C, Vernède X, Rubio LM, Nicolet Y. Structural Insights into the Mechanism of the Radical SAM Carbide Synthase NifB, a Key Nitrogenase Cofactor Maturating Enzyme. J Am Chem Soc 2020; 142:11006-11012. [PMID: 32476412 DOI: 10.1021/jacs.0c02243] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Nitrogenase is a key player in the global nitrogen cycle, as it catalyzes the reduction of dinitrogen into ammonia. The active site of the nitrogenase MoFe protein corresponds to a [MoFe7S9C-(R)-homocitrate] species designated FeMo-cofactor, whose biosynthesis and insertion requires the action of over a dozen maturation proteins provided by the NIF (for NItrogen Fixation) assembly machinery. Among them, the radical SAM protein NifB plays an essential role, concomitantly inserting a carbide ion and coupling two [Fe4S4] clusters to form a [Fe8S9C] precursor called NifB-co. Here we report on the X-ray structure of NifB from Methanotrix thermoacetophila at 1.95 Å resolution in a state pending the binding of one [Fe4S4] cluster substrate. The overall NifB architecture indicates that this enzyme has a single SAM binding site, which at this stage is occupied by cysteine residue 62. The structure reveals a unique ligand binding mode for the K1-cluster involving cysteine residues 29 and 128 in addition to histidine 42 and glutamate 65. The latter, together with cysteine 62, belongs to a loop inserted in the active site, likely protecting the already present [Fe4S4] clusters. These two residues regulate the sequence of events, controlling SAM dual reactivity and preventing unwanted radical-based chemistry before the K2 [Fe4S4] cluster substrate is loaded into the protein. The location of the K1-cluster, too far away from the SAM binding site, supports a mechanism in which the K2-cluster is the site of methylation.
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Affiliation(s)
- Ana Sosa Fajardo
- Centro de Biotecnologı́a y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnologı́a Agraria y Alimentaria, Pozuelo de Alarcón, 28223 Madrid, Spain.,Univ. Grenoble Alpes, CEA, CNRS, IBS, Metalloproteins Unit, F-38000 Grenoble, France
| | - Pierre Legrand
- Synchrotron SOLEIL, L'Orme des Merisiers, Gif-sur-Yvette, France
| | - Lucı A Payá-Tormo
- Centro de Biotecnologı́a y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnologı́a Agraria y Alimentaria, Pozuelo de Alarcón, 28223 Madrid, Spain.,Departamento de Biotecnologı́a-Biología Vegetal, Escuela Técnica Superior de Ingenierı́a Agronómica, Alimentarı́a y de Biosistemas, Universidad Politécnica de Madrid, 28040 Madrid, Spain
| | - Lydie Martin
- Univ. Grenoble Alpes, CEA, CNRS, IBS, Metalloproteins Unit, F-38000 Grenoble, France
| | - Maria Teresa Pellicer Martı Nez
- Centro de Biotecnologı́a y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnologı́a Agraria y Alimentaria, Pozuelo de Alarcón, 28223 Madrid, Spain
| | - Carlos Echavarri-Erasun
- Centro de Biotecnologı́a y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnologı́a Agraria y Alimentaria, Pozuelo de Alarcón, 28223 Madrid, Spain.,Departamento de Biotecnologı́a-Biología Vegetal, Escuela Técnica Superior de Ingenierı́a Agronómica, Alimentarı́a y de Biosistemas, Universidad Politécnica de Madrid, 28040 Madrid, Spain
| | - Xavier Vernède
- Univ. Grenoble Alpes, CEA, CNRS, IBS, Metalloproteins Unit, F-38000 Grenoble, France
| | - Luis M Rubio
- Centro de Biotecnologı́a y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnologı́a Agraria y Alimentaria, Pozuelo de Alarcón, 28223 Madrid, Spain.,Departamento de Biotecnologı́a-Biología Vegetal, Escuela Técnica Superior de Ingenierı́a Agronómica, Alimentarı́a y de Biosistemas, Universidad Politécnica de Madrid, 28040 Madrid, Spain
| | - Yvain Nicolet
- Univ. Grenoble Alpes, CEA, CNRS, IBS, Metalloproteins Unit, F-38000 Grenoble, France
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15
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Garcia AK, McShea H, Kolaczkowski B, Kaçar B. Reconstructing the evolutionary history of nitrogenases: Evidence for ancestral molybdenum-cofactor utilization. GEOBIOLOGY 2020; 18:394-411. [PMID: 32065506 PMCID: PMC7216921 DOI: 10.1111/gbi.12381] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 12/23/2019] [Accepted: 01/22/2020] [Indexed: 05/08/2023]
Abstract
The nitrogenase metalloenzyme family, essential for supplying fixed nitrogen to the biosphere, is one of life's key biogeochemical innovations. The three forms of nitrogenase differ in their metal dependence, each binding either a FeMo-, FeV-, or FeFe-cofactor where the reduction of dinitrogen takes place. The history of nitrogenase metal dependence has been of particular interest due to the possible implication that ancient marine metal availabilities have significantly constrained nitrogenase evolution over geologic time. Here, we reconstructed the evolutionary history of nitrogenases, and combined phylogenetic reconstruction, ancestral sequence inference, and structural homology modeling to evaluate the potential metal dependence of ancient nitrogenases. We find that active-site sequence features can reliably distinguish extant Mo-nitrogenases from V- and Fe-nitrogenases and that inferred ancestral sequences at the deepest nodes of the phylogeny suggest these ancient proteins most resemble modern Mo-nitrogenases. Taxa representing early-branching nitrogenase lineages lack one or more biosynthetic nifE and nifN genes that both contribute to the assembly of the FeMo-cofactor in studied organisms, suggesting that early Mo-nitrogenases may have utilized an alternate and/or simplified pathway for cofactor biosynthesis. Our results underscore the profound impacts that protein-level innovations likely had on shaping global biogeochemical cycles throughout the Precambrian, in contrast to organism-level innovations that characterize the Phanerozoic Eon.
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Affiliation(s)
- Amanda K. Garcia
- Department of Molecular and Cellular BiologyUniversity of ArizonaTucsonArizona
| | - Hanon McShea
- Department of Earth System ScienceStanford UniversityStanfordCalifornia
| | - Bryan Kolaczkowski
- Department of Microbiology and Cell ScienceUniversity of FloridaGainesvilleFlorida
| | - Betül Kaçar
- Department of Molecular and Cellular BiologyUniversity of ArizonaTucsonArizona
- Steward Observatory and the Lunar and Planetary LaboratoryUniversity of ArizonaTucsonArizona
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16
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Biosynthesis of the nitrogenase active-site cofactor precursor NifB-co in Saccharomyces cerevisiae. Proc Natl Acad Sci U S A 2019; 116:25078-25086. [PMID: 31767756 PMCID: PMC6911178 DOI: 10.1073/pnas.1904903116] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The radical S-adenosylmethionine (SAM) enzyme NifB occupies a central and essential position in nitrogenase biogenesis. NifB catalyzes the formation of an [8Fe-9S-C] cluster, called NifB-co, which constitutes the core of the active-site cofactors for all 3 nitrogenase types. Here, we produce functional NifB in aerobically cultured Saccharomyces cerevisiae Combinatorial pathway design was employed to construct 62 strains in which transcription units driving different expression levels of mitochondria-targeted nif genes (nifUSXB and fdxN) were integrated into the chromosome. Two combinatorial libraries totaling 0.7 Mb were constructed: An expression library of 6 partial clusters, including nifUSX and fdxN, and a library consisting of 28 different nifB genes mined from the Structure-Function Linkage Database and expressed at different levels according to a factorial design. We show that coexpression in yeast of the nitrogenase maturation proteins NifU, NifS, and FdxN from Azotobacter vinelandii with NifB from the archaea Methanocaldococcus infernus or Methanothermobacter thermautotrophicus yields NifB proteins equipped with [Fe-S] clusters that, as purified, support in vitro formation of NifB-co. Proof of in vivo NifB-co formation was additionally obtained. NifX as purified from aerobically cultured S. cerevisiae coexpressing M. thermautotrophicus NifB with A. vinelandii NifU, NifS, and FdxN, and engineered yeast SAM synthase supported FeMo-co synthesis, indicative of NifX carrying in vivo-formed NifB-co. This study defines the minimal genetic determinants for the formation of the key precursor in the nitrogenase cofactor biosynthetic pathway in a eukaryotic organism.
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17
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Probing the coordination and function of Fe 4S 4 modules in nitrogenase assembly protein NifB. Nat Commun 2018; 9:2824. [PMID: 30026506 PMCID: PMC6053413 DOI: 10.1038/s41467-018-05272-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 06/21/2018] [Indexed: 11/08/2022] Open
Abstract
NifB is an essential radical S-adenosylmethionine (SAM) enzyme for nitrogenase cofactor assembly. Previous studies show that NifB couples a putative pair of [Fe4S4] modules (designated K1 and K2) into an [Fe8S9C] cofactor precursor concomitant with radical SAM-dependent carbide insertion through the action of its SAM-binding [Fe4S4] module. However, the coordination and function of the NifB cluster modules remain unknown. Here, we use continuous wave and pulse electron paramagnetic resonance spectroscopy to show that K1- and K2-modules are 3-cysteine-coordinated [Fe4S4] clusters, with a histidine-derived nitrogen serving as the fourth ligand to K1 that is lost upon K1/K2-coupling. Further, we demonstrate that coexistence of SAM/K2-modules is a prerequisite for methyltransfer to K2 and hydrogen abstraction from the K2-associated methyl by a 5′-deoxyadenosyl radical. These results establish an important framework for mechanistic explorations of NifB while highlighting the utility of a synthetic-cluster-based reconstitution approach employed herein in functional analyses of iron–sulfur (FeS) enzymes. NifB is a key enzyme in the biosynthesis pathway of the nitrogenase FeMo cofactor. Here, the authors investigate the maturation of its iron-sulfur clusters by EPR and biochemical analyses, showing how individual precursor clusters participate in the formation of the final iron-sulfur cluster.
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18
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Arragain S, Jiménez-Vicente E, Scandurra AA, Burén S, Rubio LM, Echavarri-Erasun C. Diversity and Functional Analysis of the FeMo-Cofactor Maturase NifB. FRONTIERS IN PLANT SCIENCE 2017; 8:1947. [PMID: 29250084 PMCID: PMC5715403 DOI: 10.3389/fpls.2017.01947] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 10/30/2017] [Indexed: 06/07/2023]
Abstract
One of the main hurdles to engineer nitrogenase in a non-diazotrophic host is achieving NifB activity. NifB is an extremely unstable and oxygen sensitive protein that catalyzes a low-potential SAM-radical dependent reaction. The product of NifB activity is called NifB-co, a complex [8Fe-9S-C] cluster that serves as obligate intermediate in the biosyntheses of the active-site cofactors of all known nitrogenases. Here we study the diversity and phylogeny of naturally occurring NifB proteins, their protein architecture and the functions of the distinct NifB domains in order to understand what defines a catalytically active NifB. Focus is on NifB from the thermophile Chlorobium tepidum (two-domain architecture), the hyperthermophile Methanocaldococcus infernus (single-domain architecture) and the mesophile Klebsiella oxytoca (two-domain architecture), showing in silico characterization of their nitrogen fixation (nif) gene clusters, conserved NifB motifs, and functionality. C. tepidum and M. infernus NifB were able to complement an Azotobacter vinelandii (ΔnifB) mutant restoring the Nif+ phenotype and thus demonstrating their functionality in vivo. In addition, purified C. tepidum NifB exhibited activity in the in vitro NifB-dependent nitrogenase reconstitution assay. Intriguingly, changing the two-domain K. oxytoca NifB to single-domain by removal of the C-terminal NifX-like extension resulted in higher in vivo nitrogenase activity, demonstrating that this domain is not required for nitrogen fixation in mesophiles.
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Affiliation(s)
| | | | | | | | - Luis M. Rubio
- *Correspondence: Carlos Echavarri-Erasun, Luis M. Rubio,
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19
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Vaccaro BJ, Clarkson SM, Holden JF, Lee DW, Wu CH, Poole Ii FL, Cotelesage JJH, Hackett MJ, Mohebbi S, Sun J, Li H, Johnson MK, George GN, Adams MWW. Biological iron-sulfur storage in a thioferrate-protein nanoparticle. Nat Commun 2017; 8:16110. [PMID: 28726794 PMCID: PMC5524996 DOI: 10.1038/ncomms16110] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 05/30/2017] [Indexed: 11/09/2022] Open
Abstract
Iron–sulfur clusters are ubiquitous in biology and function in electron transfer and catalysis. They are assembled from iron and cysteine sulfur on protein scaffolds. Iron is typically stored as iron oxyhydroxide, ferrihydrite, encapsulated in 12 nm shells of ferritin, which buffers cellular iron availability. Here we have characterized IssA, a protein that stores iron and sulfur as thioferrate, an inorganic anionic polymer previously unknown in biology. IssA forms nanoparticles reaching 300 nm in diameter and is the largest natural metalloprotein complex known. It is a member of a widely distributed protein family that includes nitrogenase maturation factors, NifB and NifX. IssA nanoparticles are visible by electron microscopy as electron-dense bodies in the cytoplasm. Purified nanoparticles appear to be generated from 20 nm units containing ∼6,400 Fe atoms and ∼170 IssA monomers. In support of roles in both iron–sulfur storage and cluster biosynthesis, IssA reconstitutes the [4Fe-4S] cluster in ferredoxin in vitro. The biosynthesis of iron-sulfur clusters in anaerobic organisms has not been extensively investigated. Here, the authors identify and characterize a multi-subunit protein that stores iron and sulfur in thioferrate for the assembly of the clusters in Pyrococcus furiosus.
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Affiliation(s)
- Brian J Vaccaro
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA.,Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, USA
| | - Sonya M Clarkson
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, USA
| | - James F Holden
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, USA
| | - Dong-Woo Lee
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, USA
| | - Chang-Hao Wu
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, USA
| | - Farris L Poole Ii
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, USA
| | - Julien J H Cotelesage
- Department of Geological Sciences and Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C5, Canada
| | - Mark J Hackett
- Department of Geological Sciences and Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C5, Canada
| | - Sahel Mohebbi
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - Jingchuan Sun
- Cryo-EM Structural Biology Laboratory, Center for Epigenetics, Van Andel Research Institute, Grand Rapids, Michigan 49503, USA
| | - Huilin Li
- Cryo-EM Structural Biology Laboratory, Center for Epigenetics, Van Andel Research Institute, Grand Rapids, Michigan 49503, USA
| | - Michael K Johnson
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - Graham N George
- Department of Geological Sciences and Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C5, Canada
| | - Michael W W Adams
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, USA
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20
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Burén S, Jiang X, López-Torrejón G, Echavarri-Erasun C, Rubio LM. Purification and In Vitro Activity of Mitochondria Targeted Nitrogenase Cofactor Maturase NifB. FRONTIERS IN PLANT SCIENCE 2017; 8:1567. [PMID: 28955359 PMCID: PMC5601070 DOI: 10.3389/fpls.2017.01567] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 08/28/2017] [Indexed: 05/13/2023]
Abstract
Active NifB is a milestone in the process of engineering nitrogen fixing plants. NifB is an extremely O2-sensitive S-adenosyl methionine (SAM)-radical enzyme that provides the key metal cluster intermediate (NifB-co) for the biosyntheses of the active-site cofactors of all three types of nitrogenases. NifB and NifB-co are unique to diazotrophic organisms. In this work, we have expressed synthetic codon-optimized versions of NifB from the γ-proteobacterium Azotobacter vinelandii and the thermophilic methanogen Methanocaldococcus infernus in Saccharomyces cerevisiae and in Nicotiana benthamiana. NifB proteins were targeted to the mitochondria, where O2 consumption is high and bacterial-like [Fe-S] cluster assembly operates. In yeast, NifB proteins were co-expressed with NifU, NifS, and FdxN proteins that are involved in NifB [Fe-S] cluster assembly and activity. The synthetic version of thermophilic NifB accumulated in soluble form within the yeast cell, while the A. vinelandii version appeared to form aggregates. Similarly, NifB from M. infernus was expressed at higher levels in leaves of Nicotiana benthamiana and accumulated as a soluble protein while A. vinelandii NifB was mainly associated with the non-soluble cell fraction. Soluble M. infernus NifB was purified from aerobically grown yeast and biochemically characterized. The purified protein was functional in the in vitro FeMo-co synthesis assay. This work presents the first active NifB protein purified from a eukaryotic cell, and highlights the importance of screening nif genes from different organisms in order to sort the best candidates to assemble a functional plant nitrogenase.
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