1
|
Ito Y, Yoshidome D, Hidaka M, Araki Y, Ito K, Kosono S, Nishiyama M. Improvement of the nitrogenase activity in Escherichia coli that expresses the nitrogen fixation-related genes from Azotobacter vinelandii. Biochem Biophys Res Commun 2024; 728:150345. [PMID: 38971001 DOI: 10.1016/j.bbrc.2024.150345] [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: 04/09/2024] [Revised: 06/27/2024] [Accepted: 07/02/2024] [Indexed: 07/08/2024]
Abstract
The transfer of nitrogen fixation (nif) genes from diazotrophs to non-diazotrophic hosts is of increasing interest for engineering biological nitrogen fixation. A recombinant Escherichia coli strain expressing Azotobacter vinelandii 18 nif genes (nifHDKBUSVQENXYWZMF, nifiscA, and nafU) were previously constructed and showed nitrogenase activity. In the present study, we constructed several E. coli strain derivatives in which all or some of the 18 nif genes were additionally integrated into the fliK locus of the chromosome in various combinations. E. coli derivatives with the chromosomal integration of nifiscA, nifU, and nifS, which are involved in the biosynthesis of the [4Fe-4S] cluster of dinitrogenase reductase, exhibited enhanced nitrogenase activity. We also revealed that overexpression of E. coli fldA and ydbK, which encode flavodoxin and flavodoxin-reducing enzyme, respectively, enhanced nitrogenase activity, likely by facilitating electron transfer to dinitrogenase reductase. The additional expression of nifM, putatively involved in maturation of dinitrogenase reductase, further enhanced nitrogenase activity and the amount of soluble NifH. By combining these factors, we successfully improved nitrogenase activity 10-fold.
Collapse
Affiliation(s)
- Yusuke Ito
- Agro-Biotechnology Research Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan; Research & Development Division, Kikkoman Corporation, 338 Noda, Noda, Chiba, 278-0037, Japan
| | - Daisuke Yoshidome
- Agro-Biotechnology Research Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
| | - Makoto Hidaka
- Agro-Biotechnology Research Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
| | - Yasuko Araki
- Research & Development Division, Kikkoman Corporation, 338 Noda, Noda, Chiba, 278-0037, Japan
| | - Kotaro Ito
- Research & Development Division, Kikkoman Corporation, 338 Noda, Noda, Chiba, 278-0037, Japan
| | - Saori Kosono
- Agro-Biotechnology Research Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan; Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Makoto Nishiyama
- Agro-Biotechnology Research Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan; Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
| |
Collapse
|
2
|
Harris DF, Rucker HR, Garcia AK, Yang ZY, Chang SD, Feinsilber H, Kaçar B, Seefeldt LC. Ancient nitrogenases are ATP dependent. mBio 2024; 15:e0127124. [PMID: 38869277 PMCID: PMC11253609 DOI: 10.1128/mbio.01271-24] [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: 04/29/2024] [Accepted: 05/03/2024] [Indexed: 06/14/2024] Open
Abstract
Life depends on a conserved set of chemical energy currencies that are relics of early biochemistry. One of these is ATP, a molecule that, when paired with a divalent metal ion such as Mg2+, can be hydrolyzed to support numerous cellular and molecular processes. Despite its centrality to extant biochemistry, it is unclear whether ATP supported the function of ancient enzymes. We investigate the evolutionary necessity of ATP by experimentally reconstructing an ancestral variant of the N2-reducing enzyme nitrogenase. The Proterozoic ancestor is predicted to be ~540-2,300 million years old, post-dating the Great Oxidation Event. Growth rates under nitrogen-fixing conditions are ~80% of those of wild type in Azotobacter vinelandii. In the extant enzyme, the hydrolysis of two MgATP is coupled to electron transfer to support substrate reduction. The ancestor has a strict requirement for ATP with no other nucleotide triphosphate analogs (GTP, ITP, and UTP) supporting activity. Alternative divalent metal ions (Fe2+, Co2+, and Mn2+) support activity with ATP but with diminished activities compared to Mg2+, similar to the extant enzyme. Additionally, it is shown that the ancestor has an identical efficiency in ATP hydrolyzed per electron transferred to the extant of two. Our results provide direct laboratory evidence of ATP usage by an ancient enzyme.IMPORTANCELife depends on energy-carrying molecules to power many sustaining processes. There is evidence that these molecules may predate the rise of life on Earth, but how and when these dependencies formed is unknown. The resurrection of ancient enzymes provides a unique tool to probe the enzyme's function and usage of energy-carrying molecules, shedding light on their biochemical origins. Through experimental reconstruction, this research investigates the ancestral dependence of a nitrogen-fixing enzyme on the energy carrier ATP, a requirement for function in the modern enzyme. We show that the resurrected ancestor does not have generalist nucleotide specificity. Rather, the ancestor has a strict requirement for ATP, like the modern enzyme, with similar function and efficiency. The findings elucidate the early-evolved necessity of energy-yielding molecules, delineating their role in ancient biochemical processes. Ultimately, these insights contribute to unraveling the intricate tapestry of evolutionary biology and the origins of life-sustaining dependencies.
Collapse
Affiliation(s)
- Derek F. Harris
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah, USA
| | - Holly R. Rucker
- Department of Bacteriology, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | - Amanda K. Garcia
- Department of Bacteriology, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | - Zhi-Yong Yang
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah, USA
| | - Scott D. Chang
- Department of Bacteriology, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | - Hannah Feinsilber
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah, USA
| | - Betül Kaçar
- Department of Bacteriology, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | - Lance C. Seefeldt
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah, USA
| |
Collapse
|
3
|
Cuevas-Zuviría B, Garcia AK, Rivier AJ, Rucker HR, Carruthers BM, Kaçar B. Emergence of an Orphan Nitrogenase Protein Following Atmospheric Oxygenation. Mol Biol Evol 2024; 41:msae067. [PMID: 38526235 PMCID: PMC11018506 DOI: 10.1093/molbev/msae067] [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: 12/08/2023] [Revised: 03/06/2024] [Accepted: 03/19/2024] [Indexed: 03/26/2024] Open
Abstract
Molecular innovations within key metabolisms can have profound impacts on element cycling and ecological distribution. Yet, much of the molecular foundations of early evolved enzymes and metabolisms are unknown. Here, we bring one such mystery to relief by probing the birth and evolution of the G-subunit protein, an integral component of certain members of the nitrogenase family, the only enzymes capable of biological nitrogen fixation. The G-subunit is a Paleoproterozoic-age orphan protein that appears more than 1 billion years after the origin of nitrogenases. We show that the G-subunit arose with novel nitrogenase metal dependence and the ecological expansion of nitrogen-fixing microbes following the transition in environmental metal availabilities and atmospheric oxygenation that began ∼2.5 billion years ago. We identify molecular features that suggest early G-subunit proteins mediated cofactor or protein interactions required for novel metal dependency, priming ancient nitrogenases and their hosts to exploit these newly diversified geochemical environments. We further examined the degree of functional specialization in G-subunit evolution with extant and ancestral homologs using laboratory reconstruction experiments. Our results indicate that permanent recruitment of the orphan protein depended on the prior establishment of conserved molecular features and showcase how contingent evolutionary novelties might shape ecologically important microbial innovations.
Collapse
Affiliation(s)
| | - Amanda K Garcia
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, USA
| | - Alex J Rivier
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, USA
| | - Holly R Rucker
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, USA
| | - Brooke M Carruthers
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, USA
| | - Betül Kaçar
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, USA
| |
Collapse
|
4
|
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.
Collapse
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
| | | |
Collapse
|
5
|
Warmack RA, Maggiolo AO, Orta A, Wenke BB, Howard JB, Rees DC. Structural consequences of turnover-induced homocitrate loss in nitrogenase. Nat Commun 2023; 14:1091. [PMID: 36841829 PMCID: PMC9968304 DOI: 10.1038/s41467-023-36636-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 02/09/2023] [Indexed: 02/26/2023] Open
Abstract
Nitrogenase catalyzes the ATP-dependent reduction of dinitrogen to ammonia during the process of biological nitrogen fixation that is essential for sustaining life. The active site FeMo-cofactor contains a [7Fe:1Mo:9S:1C] metallocluster coordinated with an R-homocitrate (HCA) molecule. Here, we establish through single particle cryoEM and chemical analysis of two forms of the Azotobacter vinelandii MoFe-protein - a high pH turnover inactivated species and a ∆NifV variant that cannot synthesize HCA - that loss of HCA is coupled to α-subunit domain and FeMo-cofactor disordering, and formation of a histidine coordination site. We further find a population of the ∆NifV variant complexed to an endogenous protein identified through structural and proteomic approaches as the uncharacterized protein NafT. Recognition by endogenous NafT demonstrates the physiological relevance of the HCA-compromised form, perhaps for cofactor insertion or repair. Our results point towards a dynamic active site in which HCA plays a role in enabling nitrogenase catalysis by facilitating activation of the FeMo-cofactor from a relatively stable form to a state capable of reducing dinitrogen under ambient conditions.
Collapse
Affiliation(s)
- Rebeccah A Warmack
- Division of Chemistry and Chemical Engineering 147-75, California Institute of Technology, Pasadena, CA, 91125, USA.
| | - Ailiena O Maggiolo
- Division of Chemistry and Chemical Engineering 147-75, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Andres Orta
- Biochemistry and Molecular Biophysics Graduate Program, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Belinda B Wenke
- Division of Chemistry and Chemical Engineering 147-75, California Institute of Technology, Pasadena, CA, 91125, USA
| | - James B Howard
- Department of Biochemistry, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Douglas C Rees
- Division of Chemistry and Chemical Engineering 147-75, California Institute of Technology, Pasadena, CA, 91125, USA.
- Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA, USA.
| |
Collapse
|
6
|
Xuan J, He L, Wen W, Feng Y. Hydrogenase and Nitrogenase: Key Catalysts in Biohydrogen Production. Molecules 2023; 28:molecules28031392. [PMID: 36771068 PMCID: PMC9919214 DOI: 10.3390/molecules28031392] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 01/28/2023] [Accepted: 01/29/2023] [Indexed: 02/05/2023] Open
Abstract
Hydrogen with high energy content is considered to be a promising alternative clean energy source. Biohydrogen production through microbes provides a renewable and immense hydrogen supply by utilizing raw materials such as inexhaustible natural sunlight, water, and even organic waste, which is supposed to solve the two problems of "energy supply and environment protection" at the same time. Hydrogenases and nitrogenases are two classes of key enzymes involved in biohydrogen production and can be applied under different biological conditions. Both the research on enzymatic catalytic mechanisms and the innovations of enzymatic techniques are important and necessary for the application of biohydrogen production. In this review, we introduce the enzymatic structures related to biohydrogen production, summarize recent enzymatic and genetic engineering works to enhance hydrogen production, and describe the chemical efforts of novel synthetic artificial enzymes inspired by the two biocatalysts. Continual studies on the two types of enzymes in the future will further improve the efficiency of biohydrogen production and contribute to the economic feasibility of biohydrogen as an energy source.
Collapse
Affiliation(s)
- Jinsong Xuan
- Department of Bioscience and Bioengineering, School of Chemistry and Biological Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Beijing 100083, China
- Correspondence: (J.X.); (Y.F.)
| | - Lingling He
- Department of Bioscience and Bioengineering, School of Chemistry and Biological Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Beijing 100083, China
| | - Wen Wen
- Department of Bioscience and Bioengineering, School of Chemistry and Biological Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Beijing 100083, China
| | - Yingang Feng
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101, China
- Shandong Energy Institute, 189 Songling Road, Qingdao 266101, China
- Qingdao New Energy Shandong Laboratory, 189 Songling Road, Qingdao 266101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Correspondence: (J.X.); (Y.F.)
| |
Collapse
|
7
|
Garcia AK, Kolaczkowski B, Kaçar B. Reconstruction of nitrogenase predecessors suggests origin from maturase-like proteins. Genome Biol Evol 2022; 14:6531971. [PMID: 35179578 PMCID: PMC8890362 DOI: 10.1093/gbe/evac031] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/14/2022] [Indexed: 11/17/2022] Open
Abstract
The evolution of biological nitrogen fixation, uniquely catalyzed by nitrogenase enzymes, has been one of the most consequential biogeochemical innovations over life’s history. Though understanding the early evolution of nitrogen fixation has been a longstanding goal from molecular, biogeochemical, and planetary perspectives, its origins remain enigmatic. In this study, we reconstructed the evolutionary histories of nitrogenases, as well as homologous maturase proteins that participate in the assembly of the nitrogenase active-site cofactor but are not able to fix nitrogen. We combined phylogenetic and ancestral sequence inference with an analysis of predicted functionally divergent sites between nitrogenases and maturases to infer the nitrogen-fixing capabilities of their shared ancestors. Our results provide phylogenetic constraints to the emergence of nitrogen fixation and are consistent with a model wherein nitrogenases emerged from maturase-like predecessors. Though the precise functional role of such a predecessor protein remains speculative, our results highlight evolutionary contingency as a significant factor shaping the evolution of a biogeochemically essential enzyme.
Collapse
Affiliation(s)
- Amanda K Garcia
- Department of Bacteriology, University of Wisconsin - Madison, USA
| | - Bryan Kolaczkowski
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida, USA
| | - Betül Kaçar
- Department of Bacteriology, University of Wisconsin - Madison, USA
| |
Collapse
|
8
|
Van Stappen C, Jiménez-Vicente E, Pérez-González A, Yang ZY, Seefeldt LC, DeBeer S, Dean DR, Decamps L. A Conformational Role for NifW in the Maturation of Molybdenum Nitrogenase P-cluster. Chem Sci 2022; 13:3489-3500. [PMID: 35432878 PMCID: PMC8943848 DOI: 10.1039/d1sc06418e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 02/28/2022] [Indexed: 12/03/2022] Open
Abstract
Reduction of dinitrogen by molybdenum nitrogenase relies on complex metalloclusters: the [8Fe:7S] P-cluster and the [7Fe:9S:Mo:C:homocitrate] FeMo-cofactor. Although both clusters bear topological similarities and require the reductive fusion of [4Fe:4S] sub-clusters to achieve their respective assemblies, P-clusters are assembled directly on the NifD2K2 polypeptide prior to the insertion of FeMo-co, which is fully assembled separately from NifD2K2. P-cluster maturation involves the iron protein NifH2 as well as several accessory proteins, whose role has not been elucidated. In the present work, two NifD2K2 species bearing immature P-clusters were isolated from an Azotobacter vinelandii strain in which the genes encoding NifH and the accessory protein NifZ were deleted, and characterized by X-ray absorption spectroscopy and EPR. These analyses showed that both NifD2K2 complexes harbor clusters that are electronically and structurally similar, with each NifDK unit containing two [4Fe:4S]2+/+ clusters. Binding of the accessory protein NifW parallels a decrease in the distance between these clusters, as well as a subtle change in their coordination. These results support a conformational role for NifW in P-cluster biosynthesis, bringing the two [4Fe:4S] precursors closer prior to their fusion, which may be crucial in challenging cellular contexts. Upon binding of NifW, a subtle conformation change occurs in NifD2K2, decreasing the distance between the two [4Fe:4S] clusters precursors of the P-cluster in nitrogenase.![]()
Collapse
Affiliation(s)
- Casey Van Stappen
- Max Planck Institute for Chemical Energy Conversion Stiftstrasse 34-36 45470 Mülheim an der Ruhr Germany
| | - Emilio Jiménez-Vicente
- Department of Biochemistry, Virginia Polytechnic Institute and State University Blacksburg VA 24061 USA
| | - Ana Pérez-González
- Department of Biochemistry, Virginia Polytechnic Institute and State University Blacksburg VA 24061 USA
| | - Zhi-Yong Yang
- Department of Chemistry and Biochemistry, Utah State University Logan UT 84322 USA
| | - Lance C Seefeldt
- Department of Chemistry and Biochemistry, Utah State University Logan UT 84322 USA
| | - Serena DeBeer
- Max Planck Institute for Chemical Energy Conversion Stiftstrasse 34-36 45470 Mülheim an der Ruhr Germany
| | - Dennis R Dean
- Department of Biochemistry, Virginia Polytechnic Institute and State University Blacksburg VA 24061 USA
| | - Laure Decamps
- Max Planck Institute for Chemical Energy Conversion Stiftstrasse 34-36 45470 Mülheim an der Ruhr Germany
| |
Collapse
|
9
|
Waite CJ, Lindström Battle A, Bennett MH, Carey MR, Hong CK, Kotta-Loizou I, Buck M, Schumacher J. Resource Allocation During the Transition to Diazotrophy in Klebsiella oxytoca. Front Microbiol 2021; 12:718487. [PMID: 34434180 PMCID: PMC8381380 DOI: 10.3389/fmicb.2021.718487] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 07/12/2021] [Indexed: 11/13/2022] Open
Abstract
Free-living nitrogen-fixing bacteria can improve growth yields of some non-leguminous plants and, if enhanced through bioengineering approaches, have the potential to address major nutrient imbalances in global crop production by supplementing inorganic nitrogen fertilisers. However, nitrogen fixation is a highly resource-costly adaptation and is de-repressed only in environments in which sources of reduced nitrogen are scarce. Here we investigate nitrogen fixation (nif) gene expression and nitrogen starvation response signaling in the model diazotroph Klebsiella oxytoca (Ko) M5a1 during ammonium depletion and the transition to growth on atmospheric N2. Exploratory RNA-sequencing revealed that over 50% of genes were differentially expressed under diazotrophic conditions, among which the nif genes are among the most highly expressed and highly upregulated. Isotopically labelled QconCAT standards were designed for multiplexed, absolute quantification of Nif and nitrogen-stress proteins via multiple reaction monitoring mass spectrometry (MRM-MS). Time-resolved Nif protein concentrations were indicative of bifurcation in the accumulation rates of nitrogenase subunits (NifHDK) and accessory proteins. We estimate that the nitrogenase may account for more than 40% of cell protein during diazotrophic growth and occupy approximately half the active ribosome complement. The concentrations of free amino acids in nitrogen-starved cells were insufficient to support the observed rates of Nif protein expression. Total Nif protein accumulation was reduced 10-fold when the NifK protein was truncated and nitrogenase catalysis lost (nifK1–1203), implying that reinvestment of de novo fixed nitrogen is essential for further nif expression and a complete diazotrophy transition. Several amino acids accumulated in non-fixing ΔnifLA and nifK1–1203 mutants, while the rest remained highly stable despite prolonged N starvation. Monitoring post-translational uridylylation of the PII-type signaling proteins GlnB and GlnK revealed distinct nitrogen regulatory roles in Ko M5a1. GlnK uridylylation was persistent throughout the diazotrophy transition while a ΔglnK mutant exhibited significantly reduced Nif expression and nitrogen fixation activity. Altogether, these findings highlight quantitatively the scale of resource allocation required to enable the nitrogen fixation adaptation to take place once underlying signaling processes are fulfilled. Our work also provides an omics-level framework with which to model nitrogen fixation in free-living diazotrophs and inform rational engineering strategies.
Collapse
Affiliation(s)
- Christopher J Waite
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | | | - Mark H Bennett
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Matthew R Carey
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Chun K Hong
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Ioly Kotta-Loizou
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Martin Buck
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Jörg Schumacher
- Department of Life Sciences, Imperial College London, London, United Kingdom
| |
Collapse
|
10
|
Specificity of NifEN and VnfEN for the Assembly of Nitrogenase Active Site Cofactors in Azotobacter vinelandii. mBio 2021; 12:e0156821. [PMID: 34281397 PMCID: PMC8406325 DOI: 10.1128/mbio.01568-21] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The nitrogen-fixing microbe Azotobacter vinelandii has the ability to produce three genetically distinct, but mechanistically similar, components that catalyze nitrogen fixation. For two of these components, the Mo-dependent and V-dependent components, their corresponding metal-containing active site cofactors, designated FeMo-cofactor and FeV-cofactor, respectively, are preformed on separate molecular scaffolds designated NifEN and VnfEN, respectively. From prior studies, and the present work, it is now established that neither of these scaffolds can replace the other with respect to their in vivo cofactor assembly functions. Namely, a strain inactivated for NifEN cannot produce active Mo-dependent nitrogenase nor can a strain inactivated for VnfEN produce an active V-dependent nitrogenase. It is therefore proposed that metal specificities for FeMo-cofactor and FeV-cofactor formation are supplied by their respective assembly scaffolds. In the case of the third, Fe-only component, its associated active site cofactor, designated FeFe-cofactor, requires neither the NifEN nor VnfEN assembly scaffold for its formation. Furthermore, there are no other genes present in A. vinelandii that encode proteins having primary structure similarity to either NifEN or VnfEN. It is therefore concluded that FeFe-cofactor assembly is completed within its cognate catalytic protein partner without the aid of an intermediate assembly site. IMPORTANCE Biological nitrogen fixation is a complex process involving the nitrogenases. The biosynthesis of an active nitrogenase involves a large number of genes and the coordinated function of their products. Understanding the details of the assembly and activation of the different nitrogen fixation components, in particular the simplest one known so far, the Fe-only nitrogenase, would contribute to the goal of transferring the necessary genetic elements of bacterial nitrogen fixation to cereal crops to endow them with the capacity for self-fertilization. In this work, we show that there is no need for a scaffold complex for the assembly of the FeFe-cofactor, which provides the active site for Fe-only nitrogenase. These results are in agreement with previously reported genetic reconstruction experiments using a non-nitrogen-fixing microbe. In aggregate, these findings provide a high degree of confidence that the Fe-only system represents the simplest and, therefore, most attractive target for mobilizing nitrogen fixation into plants.
Collapse
|
11
|
Pérez-González A, Yang ZY, Lukoyanov DA, Dean DR, Seefeldt LC, Hoffman BM. Exploring the Role of the Central Carbide of the Nitrogenase Active-Site FeMo-cofactor through Targeted 13C Labeling and ENDOR Spectroscopy. J Am Chem Soc 2021; 143:9183-9190. [PMID: 34110795 DOI: 10.1021/jacs.1c04152] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Mo-dependent nitrogenase is a major contributor to global biological N2 reduction, which sustains life on Earth. Its multi-metallic active-site FeMo-cofactor (Fe7MoS9C-homocitrate) contains a carbide (C4-) centered within a trigonal prismatic CFe6 core resembling the structural motif of the iron carbide, cementite. The role of the carbide in FeMo-cofactor binding and activation of substrates and inhibitors is unknown. To explore this role, the carbide has been in effect selectively enriched with 13C, which enables its detailed examination by ENDOR/ESEEM spectroscopies. 13C-carbide ENDOR of the S = 3/2 resting state (E0) is remarkable, with an extremely small isotropic hyperfine coupling constant, Ca = +0.86 MHz. Turnover under high CO partial pressure generates the S = 1/2 hi-CO state, with two CO molecules bound to FeMo-cofactor. This conversion surprisingly leaves the small magnitude of the 13C carbide isotropic hyperfine-coupling constant essentially unchanged, Ca = -1.30 MHz. This indicates that both the E0 and hi-CO states exhibit an exchange-coupling scheme with nearly cancelling contributions to Ca from three spin-up and three spin-down carbide-bound Fe ions. In contrast, the anisotropic hyperfine coupling constant undergoes a symmetry change upon conversion of E0 to hi-CO that may be associated with bonding and coordination changes at Fe ions. In combination with the negligible difference between CFe6 core structures of E0 and hi-CO, these results suggest that in CO-inhibited hi-CO the dominant role of the FeMo-cofactor carbide is to maintain the core structure, rather than to facilitate inhibitor binding through changes in Fe-carbide covalency or stretching/breaking of carbide-Fe bonds.
Collapse
Affiliation(s)
- Ana Pérez-González
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Zhi-Yong Yang
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, United States
| | - Dmitriy A Lukoyanov
- Department of Chemistry Northwestern University, Evanston, Illinois 60208, United States
| | - Dennis R Dean
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Lance C Seefeldt
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, United States
| | - Brian M Hoffman
- Department of Chemistry Northwestern University, Evanston, Illinois 60208, United States
| |
Collapse
|
12
|
Yang ZY, Jimenez-Vicente E, Kallas H, Lukoyanov DA, Yang H, Martin Del Campo JS, Dean DR, Hoffman BM, Seefeldt LC. The electronic structure of FeV-cofactor in vanadium-dependent nitrogenase. Chem Sci 2021; 12:6913-6922. [PMID: 34123320 PMCID: PMC8153082 DOI: 10.1039/d0sc06561g] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 03/26/2021] [Indexed: 01/01/2023] Open
Abstract
The electronic structure of the active-site metal cofactor (FeV-cofactor) of resting-state V-dependent nitrogenase has been an open question, with earlier studies indicating that it exhibits a broad S = 3/2 EPR signal (Kramers state) having g values of ∼4.3 and 3.8, along with suggestions that it contains metal-ions with valencies [1V3+, 3Fe3+, 4Fe2+]. In the present work, genetic, biochemical, and spectroscopic approaches were combined to reveal that the EPR signals previously assigned to FeV-cofactor do not correlate with active VFe-protein, and thus cannot arise from the resting-state of catalytically relevant FeV-cofactor. It, instead, appears resting-state FeV-cofactor is either diamagnetic, S = 0, or non-Kramers, integer-spin (S = 1, 2 etc.). When VFe-protein is freeze-trapped during high-flux turnover with its natural electron-donating partner Fe protein, conditions which populate reduced states of the FeV-cofactor, a new rhombic S = 1/2 EPR signal from such a reduced state is observed, with g = [2.18, 2.12, 2.09] and showing well-defined 51V (I = 7/2) hyperfine splitting, a iso = 110 MHz. These findings indicate a different assignment for the electronic structure of the resting state of FeV-cofactor: S = 0 (or integer-spin non-Kramers state) with metal-ion valencies, [1V3+, 4Fe3+, 3Fe2+]. Our findings suggest that the V3+ does not change valency throughout the catalytic cycle.
Collapse
Affiliation(s)
- Zhi-Yong Yang
- Department of Chemistry and Biochemistry, Utah State University Logan UT 84322 USA +1-435-797-3964
| | | | - Hayden Kallas
- Department of Chemistry and Biochemistry, Utah State University Logan UT 84322 USA +1-435-797-3964
| | - Dmitriy A Lukoyanov
- Department of Chemistry, Northwestern University Evanston IL 60208 USA +1-847-491-3104
| | - Hao Yang
- Department of Chemistry, Northwestern University Evanston IL 60208 USA +1-847-491-3104
| | | | - Dennis R Dean
- Department of Biochemistry, Virginia Tech Blacksburg VA 24061 USA +1-540-231-5895
| | - Brian M Hoffman
- Department of Chemistry, Northwestern University Evanston IL 60208 USA +1-847-491-3104
| | - Lance C Seefeldt
- Department of Chemistry and Biochemistry, Utah State University Logan UT 84322 USA +1-435-797-3964
| |
Collapse
|
13
|
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.
Collapse
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.
| |
Collapse
|
14
|
Rapson TD, Gregg CM, Allen RS, Ju H, Doherty CM, Mulet X, Giddey S, Wood CC. Insights into Nitrogenase Bioelectrocatalysis for Green Ammonia Production. CHEMSUSCHEM 2020; 13:4856-4865. [PMID: 32696610 DOI: 10.1002/cssc.202001433] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 07/20/2020] [Indexed: 05/26/2023]
Abstract
There is a growing interest in using ammonia as a liquid carrier of hydrogen for energy applications. Currently, ammonia is produced industrially by the Haber-Bosch process, which requires high temperature and high pressure. In contrast, bacteria have naturally evolved an enzyme known as nitrogenase, that is capable of producing ammonia and hydrogen at ambient temperature and pressure. Therefore, nitrogenases are attractive as a potentially more efficient means to produce ammonia via harnessing the unique properties of this enzyme. In recent years, exciting progress has been made in bioelectrocatalysis using nitrogenases to produce ammonia. Here, the prospects for developing biological ammonia production are outlined, key advances in bioelectrocatalysis by nitrogenases are highlighted, and possible solutions to the obstacles faced in realising this goal are discussed.
Collapse
Affiliation(s)
- Trevor D Rapson
- CSIRO Agriculture and Food, Black Mountain, ACT, 2601, Australia
| | | | - Robert S Allen
- CSIRO Agriculture and Food, Black Mountain, ACT, 2601, Australia
| | - HyungKuk Ju
- CSIRO Energy, Private Bag 10, Clayton South, 3169, Victoria, Australia
| | - Cara M Doherty
- CSIRO Manufacturing, Private Bag 10, Clayton South, 3169, Victoria, Australia
| | - Xavier Mulet
- CSIRO Manufacturing, Private Bag 10, Clayton South, 3169, Victoria, Australia
| | - Sarbjit Giddey
- CSIRO Energy, Private Bag 10, Clayton South, 3169, Victoria, Australia
| | - Craig C Wood
- CSIRO Agriculture and Food, Black Mountain, ACT, 2601, Australia
| |
Collapse
|
15
|
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.
Collapse
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
| |
Collapse
|
16
|
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.
Collapse
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
| |
Collapse
|
17
|
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.
Collapse
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
| |
Collapse
|
18
|
Affiliation(s)
- Oliver Einsle
- Institute for Biochemistry, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Douglas C. Rees
- Division of Chemistry and Chemical Engineering, Howard Hughes Medical Institute, California Institute of Technology, Pasadena California 91125, United States
| |
Collapse
|
19
|
Abstract
As the only enzyme currently known to reduce dinitrogen (N2) to ammonia (NH3), nitrogenase is of significant interest for bio-inspired catalyst design and for new biotechnologies aiming to produce NH3 from N2. In order to reduce N2, nitrogenase must also hydrolyze at least 16 equivalents of adenosine triphosphate (MgATP), representing the consumption of a significant quantity of energy available to biological systems. Here, we review natural and engineered electron transfer pathways to nitrogenase, including strategies to redirect or redistribute electron flow in vivo towards NH3 production. Further, we also review strategies to artificially reduce nitrogenase in vitro, where MgATP hydrolysis is necessary for turnover, in addition to strategies that are capable of bypassing the requirement of MgATP hydrolysis to achieve MgATP-independent N2 reduction.
Collapse
|
20
|
Addo MA, Dos Santos PC. Distribution of Nitrogen‐Fixation Genes in Prokaryotes Containing Alternative Nitrogenases. Chembiochem 2020; 21:1749-1759. [DOI: 10.1002/cbic.202000022] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 03/04/2020] [Indexed: 01/15/2023]
Affiliation(s)
- Maame A. Addo
- Department of Chemistry Wake Forest University Winston-Salem NC 27106 USA
| | | |
Collapse
|
21
|
Demtröder L, Pfänder Y, Schäkermann S, Bandow JE, Masepohl B. NifA is the master regulator of both nitrogenase systems in Rhodobacter capsulatus. Microbiologyopen 2019; 8:e921. [PMID: 31441241 PMCID: PMC6925177 DOI: 10.1002/mbo3.921] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 07/16/2019] [Accepted: 07/18/2019] [Indexed: 01/09/2023] Open
Abstract
Rhodobacter capsulatus fixes atmospheric nitrogen (N2) by a molybdenum (Mo)‐nitrogenase and a Mo‐free iron (Fe)‐nitrogenase, whose production is induced or repressed by Mo, respectively. At low nanomolar Mo concentrations, both isoenzymes are synthesized and contribute to nitrogen fixation. Here we examined the regulatory interplay of the central transcriptional activators NifA and AnfA by proteome profiling. As expected from earlier studies, synthesis of the structural proteins of Mo‐nitrogenase (NifHDK) and Fe‐nitrogenase (AnfHDGK) required NifA and AnfA, respectively, both of which depend on the alternative sigma factor RpoN to activate expression of their target genes. Unexpectedly, NifA was found to be essential for the synthesis of Fe‐nitrogenase, electron supply to both nitrogenases, biosynthesis of their cofactors, and production of RpoN. Apparently, RpoN is the only NifA‐dependent factor required for target gene activation by AnfA, since plasmid‐borne rpoN restored anfH transcription in a NifA‐deficient strain. However, plasmid‐borne rpoN did not restore Fe‐nitrogenase activity in this strain. Taken together, NifA requirement for synthesis and activity of both nitrogenases suggests that Fe‐nitrogenase functions as a complementary nitrogenase rather than an alternative isoenzyme in R. capsulatus.
Collapse
Affiliation(s)
- Lisa Demtröder
- Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | - Yvonne Pfänder
- Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | - Sina Schäkermann
- Applied Microbiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | - Julia Elisabeth Bandow
- Applied Microbiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | - Bernd Masepohl
- Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| |
Collapse
|
22
|
Nonaka A, Yamamoto H, Kamiya N, Kotani H, Yamakawa H, Tsujimoto R, Fujita Y. Accessory Proteins of the Nitrogenase Assembly, NifW, NifX/NafY, and NifZ, Are Essential for Diazotrophic Growth in the Nonheterocystous Cyanobacterium Leptolyngbya boryana. Front Microbiol 2019; 10:495. [PMID: 30930880 PMCID: PMC6428710 DOI: 10.3389/fmicb.2019.00495] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 02/26/2019] [Indexed: 12/13/2022] Open
Abstract
Since nitrogenase is extremely vulnerable to oxygen, aerobic or micro-aerobic nitrogen-fixing organisms need to create anaerobic microenvironments in the cells for diazotrophic growth, which would be one of the major barriers to express active nitrogenase in plants in efforts to create nitrogen-fixing plants. Numerous cyanobacteria are able to fix nitrogen with nitrogenase by coping with the endogenous oxygen production by photosynthesis. Understanding of the molecular mechanisms enabling to the coexistence of nitrogen fixation and photosynthesis in nonheterocystous cyanobacteria could offer valuable insights for the transfer of nitrogen fixation capacity into plants. We previously identified the cnfR gene encoding the master regulator for the nitrogen fixation (nif) gene cluster in the genome of a nonheterocystous cyanobacterium Leptolyngbya boryana, in addition to initial characterization of the nif gene cluster. Here we isolated nine mutants, in which the nif and nif-related genes were individually knocked out in L. boryana to investigate the individual functions of (1) accessory proteins (NifW, NifX/NafY, and NifZ) in the biosynthesis of nitrogenase metallocenters, (2) serine acetyltransferase (NifP) in cysteine supply for iron-sulfur clusters, (3) pyruvate formate lyase in anaerobic metabolism, and (4) NifT and HesAB proteins. ΔnifW, ΔnifXnafY, and ΔnifZ exhibited the most severe phenotype characterized by low nitrogenase activity (<10%) and loss of diazotrophic growth ability. The phenotypes of ΔnifX, ΔnafY, and ΔnifXnafY suggested that the functions of the homologous proteins NifX and NafY partially overlap. ΔnifP exhibited significantly slower diazotrophic growth than the wild type, with lower nitrogenase activity (22%). The other four mutants (ΔpflB, ΔnifT, ΔhesA, and ΔhesB) grew diazotrophically similar to the wild type. Western blot analysis revealed a high correlation between nitrogenase activity and NifD contents, suggesting that NifD is more susceptible to proteolytic degradation than NifK in L. boryana. The phenotype of the mutants lacking the accessory proteins was more severe than that observed in heterotrophic bacteria such as Azotobacter vinelandii, which suggests that the functions of NifW, NifX/NafY, and NifZ are critical for diazotrophic growth of oxygenic photosynthetic cells. L. boryana provides a promising model for studying the molecular mechanisms that produce active nitrogenase, to facilitate the creation of nitrogen-fixing plants.
Collapse
Affiliation(s)
- Aoi Nonaka
- School of Agricultural Sciences, Nagoya University, Nagoya, Japan
| | - Haruki Yamamoto
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Narumi Kamiya
- School of Agricultural Sciences, Nagoya University, Nagoya, Japan
| | - Hiroya Kotani
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Hisanori Yamakawa
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Ryoma Tsujimoto
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Yuichi Fujita
- School of Agricultural Sciences, Nagoya University, Nagoya, Japan.,Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| |
Collapse
|
23
|
Jimenez-Vicente E, Yang ZY, Martin Del Campo JS, Cash VL, Seefeldt LC, Dean DR. The NifZ accessory protein has an equivalent function in maturation of both nitrogenase MoFe protein P-clusters. J Biol Chem 2019; 294:6204-6213. [PMID: 30846561 PMCID: PMC6484116 DOI: 10.1074/jbc.ra119.007905] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 03/01/2019] [Indexed: 11/28/2022] Open
Abstract
The Mo-dependent nitrogenase comprises two interacting components called the Fe protein and the MoFe protein. The MoFe protein is an α2β2 heterotetramer that harbors two types of complex metalloclusters, both of which are necessary for N2 reduction. One type is a 7Fe-9S-Mo-C-homocitrate species designated FeMo-cofactor, which provides the N2-binding catalytic site, and the other is an 8Fe-7S species designated the P-cluster, involved in mediating intercomponent electron transfer to FeMo-cofactor. The MoFe protein's catalytic partner, Fe protein, is also required for both FeMo-cofactor formation and the conversion of an immature form of P-clusters to the mature species. This latter process involves several assembly factors, NafH, NifW, and NifZ, and precedes FeMo-cofactor insertion. Here, using various protein affinity–based purification methods as well as in vivo, EPR spectroscopy, and MALDI measurements, we show that several MoFe protein species accumulate in a NifZ-deficient background of the nitrogen-fixing microbe Azotobacter vinelandii. These included fully active MoFe protein replete with FeMo-cofactor and mature P-cluster, inactive MoFe protein having no FeMo-cofactor and only immature P-cluster, and partially active MoFe protein having one αβ-unit with a FeMo-cofactor and mature P-cluster and the other αβ-unit with no FeMo-cofactor and immature P-cluster. Also, NifW could associate with MoFe protein having immature P-clusters and became dissociated upon P-cluster maturation. Furthermore, both P-clusters could mature in vitro without NifZ. These findings indicate that NifZ has an equivalent, although not essential, function in the maturation of both P-clusters contained within the MoFe protein.
Collapse
Affiliation(s)
- Emilio Jimenez-Vicente
- From the Department of Biochemistry, Virginia Polytechnic Institute, Blacksburg, Virginia 24061 and
| | - Zhi-Yong Yang
- the Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322
| | - Julia S Martin Del Campo
- From the Department of Biochemistry, Virginia Polytechnic Institute, Blacksburg, Virginia 24061 and
| | - Valerie L Cash
- From the Department of Biochemistry, Virginia Polytechnic Institute, Blacksburg, Virginia 24061 and
| | - Lance C Seefeldt
- the Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322
| | - Dennis R Dean
- From the Department of Biochemistry, Virginia Polytechnic Institute, Blacksburg, Virginia 24061 and
| |
Collapse
|
24
|
Harris DF, Yang ZY, Dean DR, Seefeldt LC, Hoffman BM. Kinetic Understanding of N 2 Reduction versus H 2 Evolution at the E 4(4H) Janus State in the Three Nitrogenases. Biochemistry 2018; 57:5706-5714. [PMID: 30183278 DOI: 10.1021/acs.biochem.8b00784] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The enzyme nitrogenase catalyzes the reduction of N2 to ammonia but also that of protons to H2. These reactions compete at the mechanistically central 'Janus' intermediate, denoted E4(4H), which has accumulated 4e-/4H+ as two bridging Fe-H-Fe hydrides on the active-site cofactor. This state can lose e-/H+ by hydride protonolysis (HP) or become activated by reductive elimination ( re) of the two hydrides and bind N2 with H2 loss, yielding an E4(2N2H) state that goes on to generate two NH3 molecules. Thus, E4(4H) represents the key branch point for these competing reactions. Here, we present a steady-state kinetic analysis that precisely describes this competition. The analysis demonstrates that steady-state, high-electron flux turnover overwhelmingly populates the E4 states at the expense of less reduced states, quenching HP at those states. The ratio of rate constants for E4(4H) hydride protonolysis ( kHP) versus reductive elimination ( kre) provides a sensitive measure of competition between these two processes and thus is a central parameter of nitrogenase catalysis. Analysis of measurements with the three nitrogenase variants (Mo-nitrogenase, V-nitrogenase, and Fe-nitrogenase) reveals that at a fixed N2 pressure their tendency to productively react with N2 to produce two NH3 molecules and an accompanying H2, rather than diverting electrons to the side reaction, HP production of H2, decreases with their ratio of rate constants, k re/ kHP: Mo-nitrogenase, 5.1 atm-1; V-nitrogenase, 2 atm-1; and Fe-nitrogenase, 0.77 atm-1 (namely, in a 1:0.39:0.15 ratio). Moreover, the lower catalytic effectiveness of the alternative nitrogenases, with more H2 production side reaction, is not caused by a higher kHP but by a significantly lower k re.
Collapse
Affiliation(s)
- Derek F Harris
- Department of Chemistry and Biochemistry , Utah State University , Logan , Utah 84322 , United States
| | - Zhi-Yong Yang
- Department of Chemistry and Biochemistry , Utah State University , Logan , Utah 84322 , United States
| | - Dennis R Dean
- Department of Biochemistry , Virginia Tech , Blacksburg , Virginia 24061 , United States
| | - Lance C Seefeldt
- Department of Chemistry and Biochemistry , Utah State University , Logan , Utah 84322 , United States
| | - Brian M Hoffman
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
| |
Collapse
|
25
|
|
26
|
Polyprotein strategy for stoichiometric assembly of nitrogen fixation components for synthetic biology. Proc Natl Acad Sci U S A 2018; 115:E8509-E8517. [PMID: 30061389 PMCID: PMC6130400 DOI: 10.1073/pnas.1804992115] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The requirement of maintaining balanced expression of a large number of gene products represents a major challenge to the engineering of nitrogen fixation in cereal crops, necessitating reiterative combinatorial assembly cycles to optimize monocistronic gene expression. In this study, we have explored a “fuse-and-cleave” virus-derived polyprotein strategy to reduce gene numbers and achieve balanced expression of protein components required for nitrogenase biosynthesis and activity. After testing and regrouping assemblies on the basis of expression profiles, cleavage patterns, and activity, 14 essential genes were selectively assembled into 5 giant genes that enable growth on dinitrogen. This strategy has potential advantages, not only for transferring nitrogen fixation to plants, but also for the engineering of other complex systems of profound agronomic and ecological importance. Re-engineering of complex biological systems (CBS) is an important goal for applications in synthetic biology. Efforts have been made to simplify CBS by refactoring a large number of genes with rearranged polycistrons and synthetic regulatory circuits. Here, a posttranslational protein-splicing strategy derived from RNA viruses was exploited to minimize gene numbers of the classic nitrogenase system, where the expression stoichiometry is particularly important. Operon-based nif genes from Klebsiella oxytoca were regrouped into giant genes either by fusing genes together or by expressing polyproteins that are subsequently cleaved with Tobacco Etch Virus protease. After several rounds of selection based on protein expression levels and tolerance toward a remnant C-terminal ENLYFQ-tail, a system with only five giant genes showed optimal nitrogenase activity and supported diazotrophic growth of Escherichia coli. This study provides an approach for efficient translation from an operon-based system into a polyprotein-based assembly that has the potential for portable and stoichiometric expression of the complex nitrogenase system in eukaryotic organisms.
Collapse
|
27
|
Jiménez-Vicente E, Martin Del Campo JS, Yang ZY, Cash VL, Dean DR, Seefeldt LC. Application of affinity purification methods for analysis of the nitrogenase system from Azotobacter vinelandii. Methods Enzymol 2018; 613:231-255. [DOI: 10.1016/bs.mie.2018.10.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
|