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Jiang Q, Li Y, Wang M, Cao W, Yang X, Zhang S, Guo L. Light energy utilization and microbial catalysis for enhanced biohydrogen: Ternary coupling system of triethanolamine-mediated Fe@C-Rhodobacter sphaeroides. BIORESOURCE TECHNOLOGY 2024; 401:130733. [PMID: 38670287 DOI: 10.1016/j.biortech.2024.130733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 03/27/2024] [Accepted: 04/23/2024] [Indexed: 04/28/2024]
Abstract
This study investigated the mediating effect of Triethanolamine on Fe@C-Rhodobacter sphaeroides hybrid photosynthetic system to achieve efficient biohydrogen production. The biocompatible Fe@C generates excited electrons upon exposure to light, releasing ferrum for nitrogenase synthesis, and regulating the pH of the fermentation environment. Triethanolamine was introduced to optimize the electron transfer chain, thereby improving system stability, prolonging electron lifespan, and facilitating ferrum corrosion. This, in turn, stimulated the lactic acid synthetic metabolic pathway of Rhodobacter sphaeroides, resulting in increased reducing power in the biohybrid system. The ternary coupling system was analyzed through the regulation of concentration, initial pH, and light intensity. The system achieved the highest total H2 production of 5410.9 mL/L, 1.29 times higher than the control (2360.5 mL/L). This research provides a valuable strategy for constructing ferrum-carbon-based composite-cellular biohybrid systems for photo-fermentation H2 production.
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Affiliation(s)
- Qiushi Jiang
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xianning West Road, Xi'an 710049, China
| | - Yanjing Li
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xianning West Road, Xi'an 710049, China
| | - Minmin Wang
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xianning West Road, Xi'an 710049, China
| | - Wen Cao
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xianning West Road, Xi'an 710049, China.
| | - Xueying Yang
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xianning West Road, Xi'an 710049, China
| | - Sihu Zhang
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xianning West Road, Xi'an 710049, China
| | - Liejin Guo
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xianning West Road, Xi'an 710049, China
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Addison H, Glatter T, K. A. Hochberg G, Rebelein JG. Two distinct ferredoxins are essential for nitrogen fixation by the iron nitrogenase in Rhodobacter capsulatus. mBio 2024; 15:e0331423. [PMID: 38377621 PMCID: PMC10936413 DOI: 10.1128/mbio.03314-23] [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: 12/07/2023] [Accepted: 01/29/2024] [Indexed: 02/22/2024] Open
Abstract
Nitrogenases are the only enzymes able to fix gaseous nitrogen into bioavailable ammonia and hence are essential for sustaining life. Catalysis by nitrogenases requires both a large amount of ATP and electrons donated by strongly reducing ferredoxins or flavodoxins. Our knowledge about the mechanisms of electron transfer to nitrogenase enzymes is limited: The electron transport to the iron (Fe)-nitrogenase has hardly been investigated. Here, we characterized the electron transfer pathway to the Fe-nitrogenase in Rhodobacter capsulatus via proteome analyses, genetic deletions, complementation studies, and phylogenetics. Proteome analyses revealed an upregulation of four ferredoxins under nitrogen-fixing conditions reliant on the Fe-nitrogenase in a molybdenum nitrogenase knockout strain, compared to non-nitrogen-fixing conditions. Based on these findings, R. capsulatus strains with deletions of ferredoxin (fdx) and flavodoxin (fld, nifF) genes were constructed to investigate their roles in nitrogen fixation by the Fe-nitrogenase. R. capsulatus deletion strains were characterized by monitoring diazotrophic growth and Fe-nitrogenase activity in vivo. Only deletions of fdxC or fdxN resulted in slower growth and reduced Fe-nitrogenase activity, whereas the double deletion of both fdxC and fdxN abolished diazotrophic growth. Differences in the proteomes of ∆fdxC and ∆fdxN strains, in conjunction with differing plasmid complementation behaviors of fdxC and fdxN, indicate that the two Fds likely possess different roles and functions. These findings will guide future engineering of the electron transport systems to nitrogenase enzymes, with the aim of increased electron flux and product formation.IMPORTANCENitrogenases are essential for biological nitrogen fixation, converting atmospheric nitrogen gas to bioavailable ammonia. The production of ammonia by diazotrophic organisms, harboring nitrogenases, is essential for sustaining plant growth. Hence, there is a large scientific interest in understanding the cellular mechanisms for nitrogen fixation via nitrogenases. Nitrogenases rely on highly reduced electrons to power catalysis, although we lack knowledge as to which proteins shuttle the electrons to nitrogenases within cells. Here, we characterized the electron transport to the iron (Fe)-nitrogenase in the model diazotroph Rhodobacter capsulatus, showing that two distinct ferredoxins are very important for nitrogen fixation despite having different redox centers. In addition, our research expands upon the debate on whether ferredoxins have functional redundancy or perform distinct roles within cells. Here, we observe that both essential ferredoxins likely have distinct roles based on differential proteome shifts of deletion strains and different complementation behaviors.
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Affiliation(s)
- Holly Addison
- Microbial Metalloenzymes Research Group, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Timo Glatter
- Core Facility for Mass Spectrometry & Proteomics, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Georg K. A. Hochberg
- Evolutionary Biochemistry Research Group, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
- Center for Synthetic Microbiology (SYNMIKRO), Philipps University Marburg, Marburg, Germany
| | - Johannes G. Rebelein
- Microbial Metalloenzymes Research Group, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
- Center for Synthetic Microbiology (SYNMIKRO), Philipps University Marburg, Marburg, Germany
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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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Moulin SLY, Frail S, Braukmann T, Doenier J, Steele-Ogus M, Marks JC, Mills MM, Yeh E. The endosymbiont of Epithemia clementina is specialized for nitrogen fixation within a photosynthetic eukaryote. ISME COMMUNICATIONS 2024; 4:ycae055. [PMID: 38707843 PMCID: PMC11070190 DOI: 10.1093/ismeco/ycae055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 04/05/2024] [Accepted: 04/08/2024] [Indexed: 05/07/2024]
Abstract
Epithemia spp. diatoms contain obligate, nitrogen-fixing endosymbionts, or diazoplasts, derived from cyanobacteria. These algae are a rare example of photosynthetic eukaryotes that have successfully coupled oxygenic photosynthesis with oxygen-sensitive nitrogenase activity. Here, we report a newly-isolated species, E. clementina, as a model to investigate endosymbiotic acquisition of nitrogen fixation. We demonstrate that the diazoplast, which has lost photosynthesis, provides fixed nitrogen to the diatom host in exchange for fixed carbon. To identify the metabolic changes associated with this endosymbiotic specialization, we compared the Epithemia diazoplast with its close, free-living cyanobacterial relative, Crocosphaera subtropica. Unlike C. subtropica, in which nitrogenase activity is temporally separated from photosynthesis, we show that nitrogenase activity in the diazoplast is continuous through the day (concurrent with host photosynthesis) and night. Host and diazoplast metabolism are tightly coupled to support nitrogenase activity: Inhibition of photosynthesis abolishes daytime nitrogenase activity, while nighttime nitrogenase activity no longer requires cyanobacterial glycogen storage pathways. Instead, import of host-derived carbohydrates supports nitrogenase activity throughout the day-night cycle. Carbohydrate metabolism is streamlined in the diazoplast compared to C. subtropica with retention of the oxidative pentose phosphate pathway and oxidative phosphorylation. Similar to heterocysts, these pathways may be optimized to support nitrogenase activity, providing reducing equivalents and ATP and consuming oxygen. Our results demonstrate that the diazoplast is specialized for endosymbiotic nitrogen fixation. Altogether, we establish a new model for studying endosymbiosis, perform a functional characterization of this diazotroph endosymbiosis, and identify metabolic adaptations for endosymbiotic acquisition of a critical biological function.
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Affiliation(s)
- Solène L Y Moulin
- Department of Pathology, Stanford School of Medicine, Stanford, CA 94305, United States
| | - Sarah Frail
- Department of Biochemistry, Stanford School of Medicine, Stanford, CA 94305, United States
| | - Thomas Braukmann
- Department of Pathology, Stanford School of Medicine, Stanford, CA 94305, United States
- Department of Biochemistry, Stanford School of Medicine, Stanford, CA 94305, United States
| | - Jon Doenier
- Department of Biochemistry, Stanford School of Medicine, Stanford, CA 94305, United States
| | - Melissa Steele-Ogus
- Department of Pathology, Stanford School of Medicine, Stanford, CA 94305, United States
| | - Jane C Marks
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AR 86011, United States
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ 86011, United States
| | - Matthew M Mills
- Department of Earth System Science, Stanford Doerr School of Sustainability, Stanford, CA 94305, United States
| | - Ellen Yeh
- Department of Pathology, Stanford School of Medicine, Stanford, CA 94305, United States
- Department of Microbiology & Immunology, Stanford School of Medicine, Stanford, CA 94305, United States
- Chan Zuckerberg Biohub, San Francisco, CA 94158, United States
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Yang J, Xiang N, Liu Y, Guo C, Li C, Li H, Cai S, Dixon R, Wang YP. Organelle-dependent polyprotein designs enable stoichiometric expression of nitrogen fixation components targeted to mitochondria. Proc Natl Acad Sci U S A 2023; 120:e2305142120. [PMID: 37585462 PMCID: PMC10450427 DOI: 10.1073/pnas.2305142120] [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: 03/29/2023] [Accepted: 07/06/2023] [Indexed: 08/18/2023] Open
Abstract
Introducing nitrogen fixation (nif ) genes into eukaryotic genomes and targeting Nif components to mitochondria or chloroplasts is a promising strategy for engineering nitrogen-fixing plants. A prerequisite for achieving nitrogen fixation in crops is stable and stoichiometric expression of each component in organelles. Previously, we designed a polyprotein-based nitrogenase system depending on Tobacco Etch Virus protease (TEVp) to release functional Nif components from five polyproteins. Although this system satisfies the demand for specific expression ratios of Nif components in Escherichia coli, we encountered issues with TEVp cleavage of polyproteins targeted to yeast mitochondria. To overcome this obstacle, a version of the Nif polyprotein system was constructed by replacing TEVp cleavage sites with minimal peptide sequences, identified by knowledge-based engineering, that are susceptible to cleavage by the endogenous mitochondrial-processing peptidase. This replacement not only further reduces the number of genes required, but also prevents potential precleavage of polyproteins outside the target organelle. This version of the polyprotein-based nitrogenase system achieved levels of nitrogenase activity in E. coli, comparable to those observed with the TEVp-based polyprotein nitrogenase system. When applied to yeast mitochondria, stable and balanced expression of Nif components was realized. This strategy has potential advantages, not only for transferring nitrogen fixation to eukaryotic cells, but also for the engineering of other metabolic pathways that require mitochondrial compartmentalization.
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Affiliation(s)
- Jianguo Yang
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and School of Life Sciences, Peking University, Beijing100871, China
| | - Nan Xiang
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and School of Life Sciences, Peking University, Beijing100871, China
| | - Yiheng Liu
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and School of Life Sciences, Peking University, Beijing100871, China
| | - Chenyue Guo
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and School of Life Sciences, Peking University, Beijing100871, China
| | - Chenyu Li
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and School of Life Sciences, Peking University, Beijing100871, China
| | - Hui Li
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and School of Life Sciences, Peking University, Beijing100871, China
| | - Shuyi Cai
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and School of Life Sciences, Peking University, Beijing100871, China
| | - Ray Dixon
- Department of Molecular Microbiology, John Innes Centre, NR4 7UHNorwich, United Kingdom
| | - Yi-Ping Wang
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and School of Life Sciences, Peking University, Beijing100871, China
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Johnston E, Okada S, Gregg CM, Warden AC, Rolland V, Gillespie V, Byrne K, Colgrave ML, Eamens AL, Allen RS, Wood CC. The structural components of the Azotobacter vinelandii iron-only nitrogenase, AnfDKG, form a protein complex within the plant mitochondrial matrix. PLANT MOLECULAR BIOLOGY 2023:10.1007/s11103-023-01363-3. [PMID: 37326800 DOI: 10.1007/s11103-023-01363-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 05/25/2023] [Indexed: 06/17/2023]
Abstract
A long-held goal of synthetic biology has been the transfer of a bacterial nitrogen-fixation pathway into plants to reduce the use of chemical fertiliser on crops such as rice, wheat and maize. There are three classes of bacterial nitrogenase, named after their metal requirements, containing either a MoFe-, VFe- or FeFe-cofactor, that converts N2 gas to ammonia. Relative to the Mo-nitrogenase the Fe-nitrogenase is not as efficient for catalysis but has less complex genetic and metallocluster requirements, features that may be preferable for engineering into crops. Here we report the successful targeting of bacterial Fe-nitrogenase proteins, AnfD, AnfK, AnfG and AnfH, to plant mitochondria. When expressed as a single protein AnfD was mostly insoluble in plant mitochondria, but coexpression of AnfD with AnfK improved its solubility. Using affinity-based purification of mitochondrially expressed AnfK or AnfG we were able to demonstrate a strong interaction of AnfD with AnfK and a weaker interaction of AnfG with AnfDK. This work establishes that the structural components of the Fe-nitrogenase can be engineered into plant mitochondria and form a complex, which will be a requirement for function. This report outlines the first use of Fe-nitrogenase proteins within a plant as a preliminary step towards engineering an alternative nitrogenase into crops.
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Affiliation(s)
- E Johnston
- CSIRO Environment, GPO Box 1700, Acton, ACT, 2601, Australia
- School of Environmental and Life Sciences, University of Newcastle, University Dr, Callaghan NSW 2308, Callaghan, Australia
| | - S Okada
- CSIRO Environment, GPO Box 1700, Acton, ACT, 2601, Australia
| | - C M Gregg
- CSIRO Agriculture and Food, GPO Box 1700, Acton, ACT, 2601, Australia
| | - A C Warden
- CSIRO Environment, GPO Box 1700, Acton, ACT, 2601, Australia
| | - V Rolland
- CSIRO Agriculture and Food, GPO Box 1700, Acton, ACT, 2601, Australia
| | - V Gillespie
- CSIRO Agriculture and Food, GPO Box 1700, Acton, ACT, 2601, Australia
| | - K Byrne
- CSIRO Agriculture and Food, 306 Carmody Rd, St Lucia, QLD, 4067, Australia
| | - M L Colgrave
- CSIRO Agriculture and Food, 306 Carmody Rd, St Lucia, QLD, 4067, Australia
- Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, 306 Carmody Rd, St. Lucia, QLD, 4067, Australia
| | - A L Eamens
- School of Health, University of the Sunshine Coast, Maroochydore, QLD, 4558, Australia
| | - R S Allen
- CSIRO Agriculture and Food, GPO Box 1700, Acton, ACT, 2601, Australia.
| | - C C Wood
- CSIRO Agriculture and Food, GPO Box 1700, Acton, ACT, 2601, Australia
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7
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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: 7] [Impact Index Per Article: 7.0] [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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