1
|
Fatima S, Olshansky L. Conformational control over proton-coupled electron transfer in metalloenzymes. Nat Rev Chem 2024:10.1038/s41570-024-00646-7. [PMID: 39223400 DOI: 10.1038/s41570-024-00646-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/29/2024] [Indexed: 09/04/2024]
Abstract
From the reduction of dinitrogen to the oxidation of water, the chemical transformations catalysed by metalloenzymes underlie global geochemical and biochemical cycles. These reactions represent some of the most kinetically and thermodynamically challenging processes known and require the complex choreography of the fundamental building blocks of nature, electrons and protons, to be carried out with utmost precision and accuracy. The rate-determining step of catalysis in many metalloenzymes consists of a protein structural rearrangement, suggesting that nature has evolved to leverage macroscopic changes in protein molecular structure to control subatomic changes in metallocofactor electronic structure. The proton-coupled electron transfer mechanisms operative in nitrogenase, photosystem II and ribonucleotide reductase exemplify this interplay between molecular and electronic structural control. We present the culmination of decades of study on each of these systems and clarify what is known regarding the interplay between structural changes and functional outcomes in these metalloenzyme linchpins.
Collapse
Affiliation(s)
- Saman Fatima
- Department of Chemistry, College of Liberal Arts and Sciences, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Lisa Olshansky
- Department of Chemistry, College of Liberal Arts and Sciences, University of Illinois Urbana-Champaign, Urbana, IL, USA.
- Center for Biophysics and Quantitative Biology, University of Illinois Urbana-Champaign, Urbana, IL, USA.
- Materials Research Laboratory, The Grainger College of Engineering, University of Illinois Urbana-Champaign, Urbana, IL, USA.
- The Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, IL, USA.
| |
Collapse
|
2
|
Lyons TW, Tino CJ, Fournier GP, Anderson RE, Leavitt WD, Konhauser KO, Stüeken EE. Co-evolution of early Earth environments and microbial life. Nat Rev Microbiol 2024; 22:572-586. [PMID: 38811839 DOI: 10.1038/s41579-024-01044-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/21/2024] [Indexed: 05/31/2024]
Abstract
Two records of Earth history capture the evolution of life and its co-evolving ecosystems with interpretable fidelity: the geobiological and geochemical traces preserved in rocks and the evolutionary histories captured within genomes. The earliest vestiges of life are recognized mostly in isotopic fingerprints of specific microbial metabolisms, whereas fossils and organic biomarkers become important later. Molecular biology provides lineages that can be overlayed on geologic and geochemical records of evolving life. All these data lie within a framework of biospheric evolution that is primarily characterized by the transition from an oxygen-poor to an oxygen-rich world. In this Review, we explore the history of microbial life on Earth and the degree to which it shaped, and was shaped by, fundamental transitions in the chemical properties of the oceans, continents and atmosphere. We examine the diversity and evolution of early metabolic processes, their couplings with biogeochemical cycles and their links to the oxygenation of the early biosphere. We discuss the distinction between the beginnings of metabolisms and their subsequent proliferation and their capacity to shape surface environments on a planetary scale. The evolution of microbial life and its ecological impacts directly mirror the Earth's chemical and physical evolution through cause-and-effect relationships.
Collapse
Affiliation(s)
- Timothy W Lyons
- Department of Earth and Planetary Sciences, University of California, Riverside, CA, USA.
- Virtual Planetary Laboratory, University of Washington, Seattle, WA, USA.
| | - Christopher J Tino
- Department of Earth and Planetary Sciences, University of California, Riverside, CA, USA.
| | - Gregory P Fournier
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Rika E Anderson
- Virtual Planetary Laboratory, University of Washington, Seattle, WA, USA
- Biology Department, Carleton College, Northfield, MN, USA
| | - William D Leavitt
- Department of Earth Sciences, Dartmouth College, Hanover, NH, USA
- Department of Chemistry, Dartmouth College, Hanover, NH, USA
| | - Kurt O Konhauser
- Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Eva E Stüeken
- Virtual Planetary Laboratory, University of Washington, Seattle, WA, USA
- School of Earth and Environmental Sciences, University of St Andrews, St Andrews, UK
| |
Collapse
|
3
|
Oehlmann NN, Schmidt FV, Herzog M, Goldman AL, Rebelein JG. The iron nitrogenase reduces carbon dioxide to formate and methane under physiological conditions: A route to feedstock chemicals. SCIENCE ADVANCES 2024; 10:eado7729. [PMID: 39141735 PMCID: PMC11323892 DOI: 10.1126/sciadv.ado7729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Accepted: 07/09/2024] [Indexed: 08/16/2024]
Abstract
Nitrogenases are the only known enzymes that reduce molecular nitrogen (N2) to ammonia. Recent findings have demonstrated that nitrogenases also reduce the greenhouse gas carbon dioxide (CO2), suggesting CO2 to be a competitor of N2. However, the impact of omnipresent CO2 on N2 fixation has not been investigated to date. Here, we study the competing reduction of CO2 and N2 by the two nitrogenases of Rhodobacter capsulatus, the molybdenum and the iron nitrogenase. The iron nitrogenase is almost threefold more efficient in CO2 reduction and profoundly less selective for N2 than the molybdenum isoform under mixtures of N2 and CO2. Correspondingly, the growth rate of diazotrophically grown R. capsulatus strains relying on the iron nitrogenase notably decreased after adding CO2. The in vivo CO2 activity of the iron nitrogenase facilitates the light-driven extracellular accumulation of formate and methane, one-carbon substrates for other microbes, and feedstock chemicals for a circular economy.
Collapse
Affiliation(s)
- Niels N. Oehlmann
- Research Group Microbial Metalloenzymes, Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Frederik V. Schmidt
- Research Group Microbial Metalloenzymes, Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Marcello Herzog
- Research Group Microbial Metalloenzymes, Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Annelise L. Goldman
- Research Group Microbial Metalloenzymes, Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Johannes G. Rebelein
- Research Group Microbial Metalloenzymes, Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
- Center for Synthetic Microbiology (SYNMIKRO), Philipps University Marburg, 35043 Marburg, Germany
| |
Collapse
|
4
|
Maslać N, Cadoux C, Bolte P, Murken F, Gu W, Milton RD, Wagner T. Structural comparison of (hyper-)thermophilic nitrogenase reductases from three marine Methanococcales. FEBS J 2024; 291:3454-3480. [PMID: 38696373 DOI: 10.1111/febs.17148] [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: 08/16/2023] [Revised: 01/17/2024] [Accepted: 04/17/2024] [Indexed: 05/04/2024]
Abstract
The nitrogenase reductase NifH catalyses ATP-dependent electron delivery to the Mo-nitrogenase, a reaction central to biological dinitrogen (N2) fixation. While NifHs have been extensively studied in bacteria, structural information about their archaeal counterparts is limited. Archaeal NifHs are considered more ancient, particularly those from Methanococcales, a group of marine hydrogenotrophic methanogens, which includes diazotrophs growing at temperatures near 92 °C. Here, we structurally and biochemically analyse NifHs from three Methanococcales, offering the X-ray crystal structures from meso-, thermo-, and hyperthermophilic methanogens. While NifH from Methanococcus maripaludis (37 °C) was obtained through heterologous recombinant expression, the proteins from Methanothermococcus thermolithotrophicus (65 °C) and Methanocaldococcus infernus (85 °C) were natively purified from the diazotrophic archaea. The structures from M. thermolithotrophicus crystallised as isolated exhibit high flexibility. In contrast, the complexes of NifH with MgADP obtained from the three methanogens are superposable, more rigid, and present remarkable structural conservation with their homologues. They retain key structural features of P-loop NTPases and share similar electrostatic profiles with the counterpart from the bacterial model organism Azotobacter vinelandii. In comparison to the NifH from the phylogenetically distant Methanosarcina acetivorans, these reductases do not cross-react significantly with Mo-nitrogenase from A. vinelandii. However, they associate with bacterial nitrogenase when ADP·AlF 4 - is added to mimic a transient reactive state. Accordingly, detailed surface analyses suggest that subtle substitutions would affect optimal binding during the catalytic cycle between the NifH from Methanococcales and the bacterial nitrogenase, implying differences in the N2-machinery from these ancient archaea.
Collapse
Affiliation(s)
- Nevena Maslać
- Microbial Metabolism Research Group, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Cécile Cadoux
- Department of Inorganic and Analytical Chemistry, Faculty of Sciences, University of Geneva, Switzerland
- National Centre of Competence in Research (NCCR) Catalysis, University of Geneva, Switzerland
| | - Pauline Bolte
- Microbial Metabolism Research Group, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Fenja Murken
- Microbial Metabolism Research Group, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Wenyu Gu
- Laboratory of Microbial Physiology and Resource Biorecovery, School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédéral de Lausanne, Switzerland
| | - Ross D Milton
- Department of Inorganic and Analytical Chemistry, Faculty of Sciences, University of Geneva, Switzerland
- National Centre of Competence in Research (NCCR) Catalysis, University of Geneva, Switzerland
| | - Tristan Wagner
- Microbial Metabolism Research Group, Max Planck Institute for Marine Microbiology, Bremen, Germany
| |
Collapse
|
5
|
Dean DR. On the path to [Fe-S] protein maturation: A personal perspective. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119750. [PMID: 38762171 DOI: 10.1016/j.bbamcr.2024.119750] [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: 01/17/2024] [Revised: 04/23/2024] [Accepted: 05/08/2024] [Indexed: 05/20/2024]
Abstract
Azotobacter vinelandii is a genetically tractable Gram-negative proteobacterium able to fix nitrogen (N2) under aerobic growth conditions. This narrative describes how biochemical-genetic approaches using A. vinelandii to study nitrogen fixation led to the formulation of the "scaffold hypothesis" for the assembly of both simple and complex [Fe-S] clusters associated with biological nitrogen fixation. These studies also led to the discovery of a parallel, but genetically distinct, pathway for maturation of [Fe-S] proteins that support central metabolic processes.
Collapse
Affiliation(s)
- Dennis R Dean
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061-0346, United States of America.
| |
Collapse
|
6
|
Funkner K, Poehlein A, Jehmlich N, Egelkamp R, Daniel R, von Bergen M, Rother M. Proteomic and transcriptomic analysis of selenium utilization in Methanococcus maripaludis. mSystems 2024; 9:e0133823. [PMID: 38591896 PMCID: PMC11097638 DOI: 10.1128/msystems.01338-23] [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: 12/11/2023] [Accepted: 03/14/2024] [Indexed: 04/10/2024] Open
Abstract
Methanococcus maripaludis utilizes selenocysteine- (Sec-) containing proteins (selenoproteins), mostly active in the organism's primary energy metabolism, methanogenesis. During selenium depletion, M. maripaludis employs a set of enzymes containing cysteine (Cys) instead of Sec. The genes coding for these Sec-/Cys-containing isoforms were the only genes known of which expression is influenced by the selenium status of the cell. Using proteomics and transcriptomics, approx. 7% and 12%, respectively, of all genes/proteins were found differentially expressed/synthesized in response to the selenium supply. Some of the genes identified involve methanogenesis, nitrogenase functions, and putative transporters. An increase of transcript abundance for putative transporters under selenium depletion indicated the organism's effort to tap into alternative sources of selenium. M. maripaludis is known to utilize selenite and dimethylselenide as selenium sources. To expand this list, a selenium-responsive reporter strain was assessed with nine other, environmentally relevant selenium species. While the effect of some was very similar to that of selenite, others were effectively utilized at lower concentrations. Conversely, selenate and seleno-amino acids were only utilized at unphysiologically high concentrations and two compounds were not utilized at all. To address the role of the selenium-regulated putative transporters, M. maripaludis mutant strains lacking one or two of the putative transporters were tested for the capability to utilize the different selenium species. Of the five putative transporters analyzed by loss-of-function mutagenesis, none appeared to be absolutely required for utilizing any of the selenium species tested, indicating they have redundant and/or overlapping specificities or are not dedicated selenium transporters. IMPORTANCE While selenium metabolism in microorganisms has been studied intensively in the past, global gene expression approaches have not been employed so far. Furthermore, the use of different selenium sources, widely environmentally interconvertible via biotic and abiotic processes, was also not extensively studied before. Methanococcus maripaludis JJ is ideally suited for such analyses, thanks to its known selenium usage and available genetic tools. Thus, an overall view on the selenium regulon of M. maripaludis was obtained via transcriptomic and proteomic analyses, which inspired further experimentation. This led to demonstrating the use of selenium sources M. maripaludis was previously not known to employ. Also, an attempt-although so far unsuccessful-was made to pinpoint potential selenium transporter genes, in order to deepen our understanding of trace element utilization in this important model organism.
Collapse
Affiliation(s)
- Katrina Funkner
- Faculty of Biology, Technische Universität Dresden, Dresden, Germany
| | - Anja Poehlein
- Genomic and Applied Microbiology & Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Nico Jehmlich
- Department of Molecular Systems Biology, Helmholtz Centre for Environmental Research GmbH–UFZ, Leipzig, Germany
| | - Richard Egelkamp
- Genomic and Applied Microbiology & Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Rolf Daniel
- Genomic and Applied Microbiology & Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Martin von Bergen
- Department of Molecular Systems Biology, Helmholtz Centre for Environmental Research GmbH–UFZ, Leipzig, Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
- University of Leipzig, Faculty of Life Sciences, Institute of Biochemistry, Leipzig, Germany
| | - Michael Rother
- Faculty of Biology, Technische Universität Dresden, Dresden, Germany
| |
Collapse
|
7
|
Lewis NM, Kisgeropoulos EC, Lubner CE, Fixen KR. Characterization of ferredoxins involved in electron transfer pathways for nitrogen fixation implicates differences in electronic structure in tuning 2[4Fe4S] Fd activity. J Inorg Biochem 2024; 254:112521. [PMID: 38471286 DOI: 10.1016/j.jinorgbio.2024.112521] [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: 10/11/2023] [Revised: 03/03/2024] [Accepted: 03/05/2024] [Indexed: 03/14/2024]
Abstract
Ferredoxins (Fds) are small proteins which shuttle electrons to pathways like biological nitrogen fixation. Physical properties tune the reactivity of Fds with different pathways, but knowledge on how these properties can be manipulated to engineer new electron transfer pathways is lacking. Recently, we showed that an evolved strain of Rhodopseudomonas palustris uses a new electron transfer pathway for nitrogen fixation. This pathway involves a variant of the primary Fd of nitrogen fixation in R. palustris, Fer1, in which threonine at position 11 is substituted for isoleucine (Fer1T11I). To understand why this substitution in Fer1 enables more efficient electron transfer, we used in vivo and in vitro methods to characterize Fer1 and Fer1T11I. Electrochemical characterization revealed both Fer1 and Fer1T11I have similar redox transitions (-480 mV and - 550 mV), indicating the reduction potential was unaffected despite the proximity of T11 to an iron‑sulfur (FeS) cluster of Fer1. Additionally, disruption of hydrogen bonding around an FeS cluster in Fer1 by substituting threonine with alanine (T11A) or valine (T11V) did not increase nitrogenase activity, indicating that disruption of hydrogen bonding does not explain the difference in activity observed for Fer1T11I. Electron paramagnetic resonance spectroscopy studies revealed key differences in the electronic structure of Fer1 and Fer1T11I, which indicate changes to the high spin states and/or spin-spin coupling between the FeS clusters of Fer1. Our data implicates these electronic structure differences in facilitating electron flow and sets a foundation for further investigations to understand the connection between these properties and intermolecular electron transfer.
Collapse
Affiliation(s)
- Nathan M Lewis
- Department of Plant and Microbial Biology and the Biotechnology Institute, University of Minnesota, Minneapolis, MN, United States of America
| | | | - Carolyn E Lubner
- National Renewable Energy Laboratory, Golden, CO, United States of America.
| | - Kathryn R Fixen
- Department of Plant and Microbial Biology and the Biotechnology Institute, University of Minnesota, Minneapolis, MN, United States of America.
| |
Collapse
|
8
|
Xie ZL, Jin WT, Zhou ZH. Analyses of the electronic structures of FeFe-cofactors compared with those of FeMo- and FeV-cofactors and their P-clusters. Dalton Trans 2024; 53:6529-6536. [PMID: 38299993 DOI: 10.1039/d3dt04126c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2024]
Abstract
The electronic structures of FeFe-cofactors (FeFe-cos) in resting and turnover states, together with their PN clusters from iron-only nitrogenases, have been calculated using the bond valence method, and their crystallographic data were reported recently and deposited in the Protein Data Bank (PDB codes: 8BOQ and 8OIE). The calculated results have also been compared with those of their homologous Mo- and V-nitrogenases. For FeFe-cos in the resting state, Fe1/2/4/5/6/7/8 atoms are prone to Fe3+, while the Fe3 atom shows different degrees of mixed valences. The results support that the Fe8 atom at the terminal positions of FeFe-cos possesses the same oxidation states as the Mo3+/V3+ atoms of FeMo-/FeV-cos. In the turnover state, the overall oxidation state of FeFe-co is slightly reduced than those in the resting species, and its electronic configuration is rearranged after the substitution of S2B with OH, compatible with those found in CO-bound FeV-co. Moreover, the calculations give the formal oxidation states of 6Fe2+-2Fe3+ for the electronic structures of PN clusters in Fe-nitrogenases. By the comparison of Mo-, V- and Fe-nitrogenases, the overall oxidation levels of 7Fe atoms (Fe1-Fe7) for both FeFe- and FeMo-cos in resting states are found to be higher than that of FeV-co. For the PN clusters in MoFe-, VFe- and FeFe-proteins, they all exhibit a strong reductive character.
Collapse
Affiliation(s)
- Zhen-Lang Xie
- State Key Laboratory of Physical Chemistry of Solid Surfaces and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
| | - Wan-Ting Jin
- College of Chemical and Material Engineering, Quzhou University, Quzhou, 324000, China
| | - Zhao-Hui Zhou
- State Key Laboratory of Physical Chemistry of Solid Surfaces and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
| |
Collapse
|
9
|
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
|
10
|
Somerville SV, Li Q, Wordsworth J, Jamali S, Eskandarian MR, Tilley RD, Gooding JJ. Approaches to Improving the Selectivity of Nanozymes. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2211288. [PMID: 37017492 DOI: 10.1002/adma.202211288] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 01/12/2023] [Indexed: 06/19/2023]
Abstract
Nanozymes mimic enzymes and that includes their selectivity. To achieve selectivity, significant inspiration for nanoparticle design can come from the geometric and molecular features that make enzymes selective catalysts. The two central features enzymes use are control over the arrangement of atoms in the active site and the placing of the active site down a nanoconfined substrate channel. The implementation of enzyme-inspired features has already been shown to both improve activity and selectivity of nanoparticles for a variety of catalytic and sensing applications. The tuning and control of active sites on metal nanoparticle surfaces ranges from simply changing the composition of the surface metal to sophisticated approaches such as the immobilization of single atoms on a metal substrate. Molecular frameworks provide a powerful platform for the implementation of isolated and discrete active sites while unique diffusional environments further improve selectivity. The implementation of nanoconfined substrate channels around these highly controlled active sites offers further ability to control selectivity through altering the solution environment and transport of reactants and products. Implementing these strategies together offers a unique opportunity to improve nanozyme selectivity in both sensing and catalysis.
Collapse
Affiliation(s)
- Samuel V Somerville
- School of Chemistry, Australian Centre for NanoMedicine, University of New South Wales, Sydney, 2052, Australia
| | - Qinyu Li
- School of Chemistry, Australian Centre for NanoMedicine, University of New South Wales, Sydney, 2052, Australia
| | - Johanna Wordsworth
- School of Chemistry, Australian Centre for NanoMedicine, University of New South Wales, Sydney, 2052, Australia
| | - Sina Jamali
- School of Chemistry, Australian Centre for NanoMedicine, University of New South Wales, Sydney, 2052, Australia
| | - Mohammad Reza Eskandarian
- School of Chemistry, Australian Centre for NanoMedicine, University of New South Wales, Sydney, 2052, Australia
| | - Richard D Tilley
- School of Chemistry, Australian Centre for NanoMedicine, University of New South Wales, Sydney, 2052, Australia
- Electron Microscope Unit, Mark Wainwright Analytical Centre, University of New South Wales, Sydney, 2052, Australia
| | - J Justin Gooding
- School of Chemistry, Australian Centre for NanoMedicine, University of New South Wales, Sydney, 2052, Australia
| |
Collapse
|
11
|
Wilson DWN, Fataftah MS, Mathe Z, Mercado BQ, DeBeer S, Holland PL. Three-Coordinate Nickel and Metal-Metal Interactions in a Heterometallic Iron-Sulfur Cluster. J Am Chem Soc 2024; 146:4013-4025. [PMID: 38308743 PMCID: PMC10993082 DOI: 10.1021/jacs.3c12157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2024]
Abstract
Biological multielectron reactions often are performed by metalloenzymes with heterometallic sites, such as anaerobic carbon monoxide dehydrogenase (CODH), which has a nickel-iron-sulfide cubane with a possible three-coordinate nickel site. Here, we isolate the first synthetic iron-sulfur clusters having a nickel atom with only three donors, showing that this structural feature is feasible. These have a core with two tetrahedral irons, one octahedral tungsten, and a three-coordinate nickel connected by sulfide and thiolate bridges. Electron paramagnetic resonance (EPR), Mössbauer, and superconducting quantum interference device (SQUID) data are combined with density functional theory (DFT) computations to show how the electronic structure of the cluster arises from strong magnetic coupling between the Ni, Fe, and W sites. X-ray absorption spectroscopy, together with spectroscopically validated DFT analysis, suggests that the electronic structure can be described with a formal Ni1+ atom participating in a nonpolar Ni-W σ-bond. This metal-metal bond, which minimizes spin density at Ni1+, is conserved in two cluster oxidation states. Fe-W bonding is found in all clusters, in one case stabilizing a local non-Hund state at tungsten. Based on these results, we compare different M-M interactions and speculate that other heterometallic clusters, including metalloenzyme active sites, could likewise store redox equivalents and stabilize low-valent metal centers through metal-metal bonding.
Collapse
Affiliation(s)
- Daniel W. N. Wilson
- Department of Chemistry, Yale University, 225 Prospect St., New Haven, Connecticut 06520, USA
| | - Majed S. Fataftah
- Department of Chemistry, Yale University, 225 Prospect St., New Haven, Connecticut 06520, USA
| | - Zachary Mathe
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Brandon Q. Mercado
- Department of Chemistry, Yale University, 225 Prospect St., New Haven, Connecticut 06520, USA
| | - Serena DeBeer
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Patrick L. Holland
- Department of Chemistry, Yale University, 225 Prospect St., New Haven, Connecticut 06520, USA
| |
Collapse
|
12
|
Siegbahn PEM, Wei WJ. The energetics of N 2 reduction by vanadium containing nitrogenase. Phys Chem Chem Phys 2024; 26:1684-1695. [PMID: 38126534 DOI: 10.1039/d3cp04698b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
The main class of nitrogenases has a molybdenum in its cofactor. A mechanism for Mo-nitrogenase has recently been described. In the present study, another class of nitrogenases has been studied, the one with a vanadium instead of a molybdenum in its cofactor. It is generally believed that these classes use the same general mechanism to activate nitrogen. The same methodology has been used here as the one used for Mo-nitrogenase. N2 activation is known to occur after four reductions in the catalytic cycle, in the E4 state. The main features of the mechanism for Mo-nitrogenase found in the previous study are an activation process in four steps prior to catalysis, the release of a sulfide during the activation steps and the formation of H2 from two hydrides in E4, just before N2 is activated. The same features have been found here for V-nitrogenase. A difference is that five steps are needed in the activation process, which explains why the ground state of V-nitrogenase is a triplet (even number) and the one for Mo-nitrogenase is a quartet (odd number). The reason an additional step is needed for V-nitrogenase is that V3+ can be reduced to V2+, in contrast to the case for Mo3+ in Mo-nitrogenase. The fact that V3+ is Jahn-Teller active has important consequences. N2H2 is formed in E4 with reasonably small barriers.
Collapse
Affiliation(s)
- Per E M Siegbahn
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91, Stockholm, Sweden.
| | - Wen-Jie Wei
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91, Stockholm, Sweden.
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica, Hubei Key Laboratory of Materials Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| |
Collapse
|
13
|
Schmidt FV, Schulz L, Zarzycki J, Prinz S, Oehlmann NN, Erb TJ, Rebelein JG. Structural insights into the iron nitrogenase complex. Nat Struct Mol Biol 2024; 31:150-158. [PMID: 38062208 PMCID: PMC10803253 DOI: 10.1038/s41594-023-01124-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 09/12/2023] [Indexed: 01/24/2024]
Abstract
Nitrogenases are best known for catalyzing the reduction of dinitrogen to ammonia at a complex metallic cofactor. Recently, nitrogenases were shown to reduce carbon dioxide (CO2) and carbon monoxide to hydrocarbons, offering a pathway to recycle carbon waste into hydrocarbon products. Among the three nitrogenase isozymes, the iron nitrogenase has the highest wild-type activity for the reduction of CO2, but the molecular architecture facilitating these activities has remained unknown. Here, we report a 2.35-Å cryogenic electron microscopy structure of the ADP·AlF3-stabilized iron nitrogenase complex from Rhodobacter capsulatus, revealing an [Fe8S9C-(R)-homocitrate] cluster in the active site. The enzyme complex suggests that the iron nitrogenase G subunit is involved in cluster stabilization and substrate channeling and confers specificity between nitrogenase reductase and catalytic component proteins. Moreover, the structure highlights a different interface between the two catalytic halves of the iron and the molybdenum nitrogenase, potentially influencing the intrasubunit 'communication' and thus the nitrogenase mechanism.
Collapse
Affiliation(s)
- Frederik V Schmidt
- Microbial Metalloenzymes Research Group, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Luca Schulz
- Department of Biochemistry and Synthetic Metabolism, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Jan Zarzycki
- Department of Biochemistry and Synthetic Metabolism, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Simone Prinz
- Central Electron Microscopy Facility, Max Planck Institute of Biophysics, Frankfurt am Main, Germany
| | - Niels N Oehlmann
- Microbial Metalloenzymes Research Group, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Tobias J Erb
- Department of Biochemistry and Synthetic Metabolism, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Johannes G Rebelein
- Microbial Metalloenzymes Research Group, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany.
| |
Collapse
|
14
|
Warmack RA, Rees DC. Nitrogenase beyond the Resting State: A Structural Perspective. Molecules 2023; 28:7952. [PMID: 38138444 PMCID: PMC10745740 DOI: 10.3390/molecules28247952] [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: 11/06/2023] [Revised: 11/30/2023] [Accepted: 12/01/2023] [Indexed: 12/24/2023] Open
Abstract
Nitrogenases have the remarkable ability to catalyze the reduction of dinitrogen to ammonia under physiological conditions. How does this happen? The current view of the nitrogenase mechanism focuses on the role of hydrides, the binding of dinitrogen in a reductive elimination process coupled to loss of dihydrogen, and the binding of substrates to a binuclear site on the active site cofactor. This review focuses on recent experimental characterizations of turnover relevant forms of the enzyme determined by cryo-electron microscopy and other approaches, and comparison of these forms to the resting state enzyme and the broader family of iron sulfur clusters. Emerging themes include the following: (i) The obligatory coupling of protein and electron transfers does not occur in synthetic and small-molecule iron-sulfur clusters. The coupling of these processes in nitrogenase suggests that they may involve unique features of the cofactor, such as hydride formation on the trigonal prismatic arrangement of irons, protonation of belt sulfurs, and/or protonation of the interstitial carbon. (ii) Both the active site cofactor and protein are dynamic under turnover conditions; the changes are such that more highly reduced forms may differ in key ways from the resting-state structure. Homocitrate appears to play a key role in coupling cofactor and protein dynamics. (iii) Structural asymmetries are observed in nitrogenase under turnover-relevant conditions by cryo-electron microscopy, although the mechanistic relevance of these states (such as half-of-sites reactivity) remains to be established.
Collapse
Affiliation(s)
- Rebeccah A. Warmack
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
- Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA 91125, USA
| | - Douglas C. Rees
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
- Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA 91125, USA
| |
Collapse
|
15
|
Einsle O. On the Shoulders of Giants-Reaching for Nitrogenase. Molecules 2023; 28:7959. [PMID: 38138449 PMCID: PMC10745432 DOI: 10.3390/molecules28247959] [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: 10/08/2023] [Revised: 11/14/2023] [Accepted: 11/27/2023] [Indexed: 12/24/2023] Open
Abstract
Only a single enzyme system-nitrogenase-carries out the conversion of atmospheric N2 into bioavailable ammonium, an essential prerequisite for all organismic life. The reduction of this inert substrate at ambient conditions poses unique catalytic challenges that strain our mechanistic understanding even after decades of intense research. Structural biology has added its part to this greater tapestry, and in this review, I provide a personal (and highly biased) summary of the parts of the story to which I had the privilege to contribute. It focuses on the crystallographic analysis of the three isoforms of nitrogenases at high resolution and the binding of ligands and inhibitors to the active-site cofactors of the enzyme. In conjunction with the wealth of available biochemical, biophysical, and spectroscopic data on the protein, this has led us to a mechanistic hypothesis based on an elementary mechanism of repetitive hydride formation and insertion.
Collapse
Affiliation(s)
- Oliver Einsle
- Institute of Biochemistry, Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, 79104 Freiburg im Breisgau, Germany
| |
Collapse
|
16
|
Einsle O. Catalysis and structure of nitrogenases. Curr Opin Struct Biol 2023; 83:102719. [PMID: 37802004 DOI: 10.1016/j.sbi.2023.102719] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 09/03/2023] [Accepted: 09/06/2023] [Indexed: 10/08/2023]
Abstract
In providing bioavailable nitrogen as building blocks for all classes of biomacromolecules, biological nitrogen fixation is an essential process for all organismic life. Only a single enzyme, nitrogenase, performs this task at ambient conditions and with ATP as an energy source. The assembly of the complex iron-sulfur enzyme nitrogenase and its catalytic mechanism remains a matter of intense study. Recent progress in the structural analysis of the three known isoforms of nitrogenase-differentiated primarily by the heterometal in their active site cofactor-has revealed a degree of structural plasticity of these clusters that suggest two distinct binding sites for substrates and reaction intermediates. A mechanistic proposal based on this finding integrates most of the available experimental data. Furthermore, the first applications of high-resolution cryo-electron microscopy have highlighted further dynamic conformational changes. Structures obtained under turnover conditions support the proposed alternating half-site reactivity in the C2-symmetric nitrogenase complex.
Collapse
Affiliation(s)
- Oliver Einsle
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, 79104 Freiburg im Breisgau, Germany.
| |
Collapse
|
17
|
Zhu SS, Xie ZL, Deng L, Wang SY, Ni LB, Zhou ZH. Protonated and deprotonated vanadyl imidazole tartrates for the mimics of the vanadium coordination in the FeV-cofactor of V-nitrogenase. Dalton Trans 2023; 52:16849-16857. [PMID: 37910198 DOI: 10.1039/d3dt02903d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2023]
Abstract
Chiral imidazole-based oxidovanadium tartrates (H2im)2[Δ,Λ-VIV2O2(R,R-H2tart)(R,R-tart)(Him)2]·Him (1, H4tart = tartaric acid, Him = imidazole) and [Λ,Λ-VIV2O2(R,R-tart)(Him)6]·4H2O (2) and their corresponding enantiomers (H2im)2[Λ,Δ-VIV2O2(S,S-H2tart)(S,S-tart)(Him)2]·Him (3) and [Δ,Δ-VIV2O2(S,S-tart)(Him)6]·4H2O (4) were obtained in alkaline solutions. Interestingly, the tartrates chelate with vanadium bidentately through α-alkoxy/α-hydroxy and α-carboxy groups and imidazole coordinates monodentately through nitrogen atom. It is worth noting that complexes 1 and 3 contain both protonated α-hydroxy and deprotonated α-alkoxy groups simultaneously, which have short V-Oα-alkoxy distances [1.976(4)av Å in 1-4] and long V-Oα-hydroxy distances [2.237(3)av Å in 1 and 2.230(2)av Å in 3]. There is an interesting strong intramolecular hydrogen bond [O(11)⋯O(1) 2.731(5) Å] between the two parts in 1 and 3. The protonated V-O distances are closer to the average bond distance in reported FeV-cofactors (FeV-cos, V-Oα-alkoxy 2.156av Å) in VFe proteins, which corresponds to the feasible protonation of coordinated α-hydroxy in R-homocitrate in V-nitrogenase, showing the homocitrate in the mechanistic model for nitrogen reduction as a secondary proton donor. Furthermore, vibrational circular dichroism (VCD) and IR spectra of 1-4 pointed out the disparity between the characteristic vibrations of the C-O and C-OH groups clearly. EPR experiment and theoretical calculations support +4 oxidation states for vanadium in 1-4. Solution 13C {1H} NMR spectra and CV analyses exhibited the solution properties for 1 and 2, respectively, which indicates that there should be a rapid exchange equilibrium between the protonated and deprotonated species in solutions.
Collapse
Affiliation(s)
- Shuang-Shuang Zhu
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
| | - Zhen-Lang Xie
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
| | - Lan Deng
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
| | - Si-Yuan Wang
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
| | - Lu-Bin Ni
- School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002, Jiangsu, China
| | - Zhao-Hui Zhou
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
| |
Collapse
|
18
|
Chanderban M, Hill CA, Dhamad AE, Lessner DJ. Expression of V-nitrogenase and Fe-nitrogenase in Methanosarcina acetivorans is controlled by molybdenum, fixed nitrogen, and the expression of Mo-nitrogenase. Appl Environ Microbiol 2023; 89:e0103323. [PMID: 37695043 PMCID: PMC10537573 DOI: 10.1128/aem.01033-23] [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: 06/20/2023] [Accepted: 07/07/2023] [Indexed: 09/12/2023] Open
Abstract
All nitrogen-fixing bacteria and archaea (diazotrophs) use molybdenum (Mo) nitrogenase to reduce dinitrogen (N2) to ammonia, with some also containing vanadium (V) and iron-only (Fe) nitrogenases that lack Mo. Among diazotrophs, the regulation and usage of the alternative V-nitrogenase and Fe-nitrogenase in methanogens are largely unknown. Methanosarcina acetivorans contains nif, vnf, and anf gene clusters encoding putative Mo-nitrogenase, V-nitrogenase, and Fe-nitrogenase, respectively. This study investigated nitrogenase expression and growth by M. acetivorans in response to fixed nitrogen, Mo/V availability, and CRISPRi repression of the nif, vnf, and/or anf gene clusters. The availability of Mo and V significantly affected growth of M. acetivorans with N2 but not with NH4Cl. M. acetivorans exhibited the fastest growth rate and highest cell yield during growth with N2 in medium containing Mo, and the slowest growth in medium lacking Mo and V. qPCR analysis revealed the transcription of the nif operon is only moderately affected by depletion of fixed nitrogen and Mo, whereas vnf and anf transcription increased significantly when fixed nitrogen and Mo were depleted, with removal of Mo being key. Immunoblot analysis revealed Mo-nitrogenase is detected when fixed nitrogen is depleted regardless of Mo availability, while V-nitrogenase and Fe-nitrogenase are detected only in the absence of fixed nitrogen and Mo. CRISPRi repression studies revealed that V-nitrogenase and/or Fe-nitrogenase are required for Mo-independent diazotrophy, and unexpectedly that the expression of Mo-nitrogenase is also required. These results reveal that alternative nitrogenase production in M. acetivorans is tightly controlled and dependent on Mo-nitrogenase expression. IMPORTANCE Methanogens and closely related methanotrophs are the only archaea known or predicted to possess nitrogenase. Methanogens play critical roles in both the global biological nitrogen and carbon cycles. Moreover, methanogens are an ancient microbial lineage and nitrogenase likely originated in methanogens. An understanding of the usage and properties of nitrogenases in methanogens can provide new insight into the evolution of nitrogen fixation and aid in the development nitrogenase-based biotechnology. This study provides the first evidence that a methanogen can produce all three forms of nitrogenases, including simultaneously. The results reveal components of Mo-nitrogenase regulate or are needed to produce V-nitrogenase and Fe-nitrogenase in methanogens, a result not seen in bacteria. Overall, this study provides a foundation to understand the assembly, regulation, and activity of the alternative nitrogenases in methanogens.
Collapse
Affiliation(s)
- Melissa Chanderban
- Department of Biological Sciences, University of Arkansas-Fayetteville, Fayetteville, Arkansas, USA
| | - Christopher A. Hill
- Department of Biological Sciences, University of Arkansas-Fayetteville, Fayetteville, Arkansas, USA
| | - Ahmed E. Dhamad
- Department of Biological Sciences, University of Arkansas-Fayetteville, Fayetteville, Arkansas, USA
- Department of Biological Sciences, Wasit University, Wasit, Iraq
| | - Daniel J. Lessner
- Department of Biological Sciences, University of Arkansas-Fayetteville, Fayetteville, Arkansas, USA
| |
Collapse
|
19
|
Brown AC, Suess DLM. An Iron-Sulfur Cluster with a Highly Pyramidalized Three-Coordinate Iron Center and a Negligible Affinity for Dinitrogen. J Am Chem Soc 2023; 145:20088-20096. [PMID: 37656961 PMCID: PMC10824254 DOI: 10.1021/jacs.3c07677] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/03/2023]
Abstract
Attempts to generate open coordination sites for N2 binding at synthetic Fe-S clusters often instead result in cluster oligomerization. Recently, it was shown for Mo-Fe-S clusters that such oligomerization reactions can be prevented through the use of sterically protective supporting ligands, thereby enabling N2 complex formation. Here, this strategy is extended to Fe-only Fe-S clusters. One-electron reduction of (IMes)3Fe4S4Cl (IMes = 1,3-dimesitylimidazol-2-ylidene) forms the transiently stable edge-bridged double cubane (IMes)6Fe8S8, which loses two IMes ligands to form the face-bridged double-cubane, (IMes)4Fe8S8. The finding that the three supporting IMes ligands do not confer sufficient protection to curtail cluster oligomerization prompted the design of a new N-heterocyclic carbene, SIArMe,iPr (1,3-bis(3,5-diisopropyl-2,6-dimethylphenyl)-2-imidazolidinylidene; abbreviated as SIAr), that features bulky groups strategically placed in remote positions. When the reduction of (SIAr)3Fe4S4Cl or [(SIAr)3Fe4S4(THF)]+ is conducted in the presence of SIAr, the formation of (SIAr)4Fe8S8 is indeed suppressed, permitting characterization of the reduced [Fe4S4]0 product. Surprisingly, rather than being an N2 complex, the product is simply (SIAr)3Fe4S4: a cluster with a three-coordinate Fe site that adopts an unusually pyramidalized geometry. Although (SIAr)3Fe4S4 does not coordinate N2 to any appreciable extent under the surveyed conditions, it does bind CO to form (SIAr)3Fe4S4(CO). This finding demonstates that the binding pocket at the unique Fe is not too small for N2; instead, the exceptionally weak affinity for N2 can be attributed to weak Fe-N2 bonding. The differences in the N2 coordination chemistry between sterically protected Mo-Fe-S clusters and Fe-only Fe-S clusters are discussed.
Collapse
Affiliation(s)
- Alexandra C Brown
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Daniel L M Suess
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| |
Collapse
|
20
|
Cadoux C, Ratcliff D, Maslać N, Gu W, Tsakoumagkos I, Hoogendoorn S, Wagner T, Milton RD. Nitrogen Fixation and Hydrogen Evolution by Sterically Encumbered Mo-Nitrogenase. JACS AU 2023; 3:1521-1533. [PMID: 37234119 PMCID: PMC10207099 DOI: 10.1021/jacsau.3c00165] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 04/20/2023] [Indexed: 05/27/2023]
Abstract
The substrate-reducing proteins of all nitrogenases (MoFe, VFe, and FeFe) are organized as α2ß2(γ2) multimers with two functional halves. While their dimeric organization could afford improved structural stability of nitrogenases in vivo, previous research has proposed both negative and positive cooperativity contributions with respect to enzymatic activity. Here, a 1.4 kDa peptide was covalently introduced in the proximity of the P cluster, corresponding to the Fe protein docking position. The Strep-tag carried by the added peptide simultaneously sterically inhibits electron delivery to the MoFe protein and allows the isolation of partially inhibited MoFe proteins (where the half-inhibited MoFe protein was targeted). We confirm that the partially functional MoFe protein retains its ability to reduce N2 to NH3, with no significant difference in selectivity over obligatory/parasitic H2 formation. Our experiment concludes that wild-type nitrogenase exhibits negative cooperativity during the steady state regarding H2 and NH3 formation (under Ar or N2), with one-half of the MoFe protein inhibiting turnover in the second half. This emphasizes the presence and importance of long-range (>95 Å) protein-protein communication in biological N2 fixation in Azotobacter vinelandii.
Collapse
Affiliation(s)
- Cécile Cadoux
- Department
of Inorganic and Analytical Chemistry, Faculty of Sciences, University of Geneva, Quai Ernest-Ansermet 30, 1211 Geneva 4, Switzerland
- National
Centre of Competence in Research (NCCR) Catalysis, University of Geneva, Quai Ernest-Ansermet 30, 1211 Geneva 4, Switzerland
| | - Daniel Ratcliff
- Department
of Inorganic and Analytical Chemistry, Faculty of Sciences, University of Geneva, Quai Ernest-Ansermet 30, 1211 Geneva 4, Switzerland
- National
Centre of Competence in Research (NCCR) Catalysis, University of Geneva, Quai Ernest-Ansermet 30, 1211 Geneva 4, Switzerland
| | - Nevena Maslać
- Max
Planck Institute for Marine Microbiology, Celsiusstraße 1, 28359 Bremen, Germany
| | - Wenyu Gu
- Department
of Chemical Engineering, Stanford University, Stanford, California 94305, United States
| | - Ioannis Tsakoumagkos
- Department
of Organic Chemistry, National Center of Competence in Research (NCCR)
Chemical Biology, University of Geneva, Quai Ernest-Ansermet 30, 1211 Geneva 4, Switzerland
| | - Sascha Hoogendoorn
- Department
of Organic Chemistry, National Center of Competence in Research (NCCR)
Chemical Biology, University of Geneva, Quai Ernest-Ansermet 30, 1211 Geneva 4, Switzerland
| | - Tristan Wagner
- Max
Planck Institute for Marine Microbiology, Celsiusstraße 1, 28359 Bremen, Germany
| | - Ross D. Milton
- Department
of Inorganic and Analytical Chemistry, Faculty of Sciences, University of Geneva, Quai Ernest-Ansermet 30, 1211 Geneva 4, Switzerland
- National
Centre of Competence in Research (NCCR) Catalysis, University of Geneva, Quai Ernest-Ansermet 30, 1211 Geneva 4, Switzerland
| |
Collapse
|
21
|
Yang ZY, Badalyan A, Hoffman BM, Dean DR, Seefeldt LC. The Fe Protein Cycle Associated with Nitrogenase Catalysis Requires the Hydrolysis of Two ATP for Each Single Electron Transfer Event. J Am Chem Soc 2023; 145:5637-5644. [PMID: 36857604 DOI: 10.1021/jacs.2c09576] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2023]
Abstract
A central feature of the current understanding of dinitrogen (N2) reduction by the enzyme nitrogenase is the proposed coupling of the hydrolysis of two ATP, forming two ADP and two Pi, to the transfer of one electron from the Fe protein component to the MoFe protein component, where substrates are reduced. A redox-active [4Fe-4S] cluster associated with the Fe protein is the agent of electron delivery, and it is well known to have a capacity to cycle between a one-electron-reduced [4Fe-4S]1+ state and an oxidized [4Fe-4S]2+ state. Recently, however, it has been shown that certain reducing agents can be used to further reduce the Fe protein [4Fe-4S] cluster to a super-reduced, all-ferrous [4Fe-4S]0 state that can be either diamagnetic (S = 0) or paramagnetic (S = 4). It has been proposed that the super-reduced state might fundamentally alter the existing model for nitrogenase energy utilization by the transfer of two electrons per Fe protein cycle linked to hydrolysis of only two ATP molecules. Here, we measure the number of ATP consumed for each electron transfer under steady-state catalysis while the Fe protein cluster is in the [4Fe-4S]1+ state and when it is in the [4Fe-4S]0 state. Both oxidation states of the Fe protein are found to operate by hydrolyzing two ATP for each single-electron transfer event. Thus, regardless of its initial redox state, the Fe protein transfers only one electron at a time to the MoFe protein in a process that requires the hydrolysis of two ATP.
Collapse
Affiliation(s)
- Zhi-Yong Yang
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, United States
| | - Artavazd Badalyan
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, United States
| | - Brian M Hoffman
- Departments of Chemistry and Molecular Biosciences, 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
| |
Collapse
|
22
|
Shulenberger KE, Jilek MR, Sherman SJ, Hohman BT, Dukovic G. Electronic Structure and Excited State Dynamics of Cadmium Chalcogenide Nanorods. Chem Rev 2023; 123:3852-3903. [PMID: 36881852 DOI: 10.1021/acs.chemrev.2c00676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
Abstract
The cylindrical quasi-one-dimensional shape of colloidal semiconductor nanorods (NRs) gives them unique electronic structure and optical properties. In addition to the band gap tunability common to nanocrystals, NRs have polarized light absorption and emission and high molar absorptivities. NR-shaped heterostructures feature control of electron and hole locations as well as light emission energy and efficiency. We comprehensively review the electronic structure and optical properties of Cd-chalcogenide NRs and NR heterostructures (e.g., CdSe/CdS dot-in-rods, CdSe/ZnS rod-in-rods), which have been widely investigated over the last two decades due in part to promising optoelectronic applications. We start by describing methods for synthesizing these colloidal NRs. We then detail the electronic structure of single-component and heterostructure NRs and follow with a discussion of light absorption and emission in these materials. Next, we describe the excited state dynamics of these NRs, including carrier cooling, carrier and exciton migration, radiative and nonradiative recombination, multiexciton generation and dynamics, and processes that involve trapped carriers. Finally, we describe charge transfer from photoexcited NRs and connect the dynamics of these processes with light-driven chemistry. We end with an outlook that highlights some of the outstanding questions about the excited state properties of Cd-chalcogenide NRs.
Collapse
Affiliation(s)
| | - Madison R Jilek
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Skylar J Sherman
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Benjamin T Hohman
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Gordana Dukovic
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States.,Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, Boulder, Colorado 80309, United States.,Materials Science and Engineering, University of Colorado Boulder, Boulder, Colorado 80303, United States
| |
Collapse
|
23
|
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
|
24
|
Lycus P, Einsle O, Zhang L. Structural biology of proteins involved in nitrogen cycling. Curr Opin Chem Biol 2023; 74:102278. [PMID: 36889028 DOI: 10.1016/j.cbpa.2023.102278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/31/2023] [Accepted: 02/02/2023] [Indexed: 03/08/2023]
Abstract
Microbial metabolic processes drive the global nitrogen cycle through sophisticated and often unique metalloenzymes that facilitate difficult redox reactions at ambient temperature and pressure. Understanding the intricacies of these biological nitrogen transformations requires a detailed knowledge that arises from the combination of a multitude of powerful analytical techniques and functional assays. Recent developments in spectroscopy and structural biology have provided new, powerful tools for addressing existing and emerging questions, which have gained urgency due to the global environmental implications of these fundamental reactions. The present review focuses on the recent contributions of the wider area of structural biology to understanding nitrogen metabolism, opening new avenues for biotechnological applications to better manage and balance the challenges of the global nitrogen cycle.
Collapse
Affiliation(s)
- Pawel Lycus
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, 79104, Freiburg im Breisgau, Germany; Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Oliver Einsle
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, 79104, Freiburg im Breisgau, Germany.
| | - Lin Zhang
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, 79104, Freiburg im Breisgau, Germany.
| |
Collapse
|
25
|
Garcia AK, Harris DF, Rivier AJ, Carruthers BM, Pinochet-Barros A, Seefeldt LC, Kaçar B. Nitrogenase resurrection and the evolution of a singular enzymatic mechanism. eLife 2023; 12:e85003. [PMID: 36799917 PMCID: PMC9977276 DOI: 10.7554/elife.85003] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 02/16/2023] [Indexed: 02/18/2023] Open
Abstract
The planetary biosphere is powered by a suite of key metabolic innovations that emerged early in the history of life. However, it is unknown whether life has always followed the same set of strategies for performing these critical tasks. Today, microbes access atmospheric sources of bioessential nitrogen through the activities of just one family of enzymes, nitrogenases. Here, we show that the only dinitrogen reduction mechanism known to date is an ancient feature conserved from nitrogenase ancestors. We designed a paleomolecular engineering approach wherein ancestral nitrogenase genes were phylogenetically reconstructed and inserted into the genome of the diazotrophic bacterial model, Azotobacter vinelandii, enabling an integrated assessment of both in vivo functionality and purified nitrogenase biochemistry. Nitrogenase ancestors are active and robust to variable incorporation of one or more ancestral protein subunits. Further, we find that all ancestors exhibit the reversible enzymatic mechanism for dinitrogen reduction, specifically evidenced by hydrogen inhibition, which is also exhibited by extant A. vinelandii nitrogenase isozymes. Our results suggest that life may have been constrained in its sampling of protein sequence space to catalyze one of the most energetically challenging biochemical reactions in nature. The experimental framework established here is essential for probing how nitrogenase functionality has been shaped within a dynamic, cellular context to sustain a globally consequential metabolism.
Collapse
Affiliation(s)
- Amanda K Garcia
- Department of Bacteriology, University of Wisconsin–MadisonMadisonUnited States
| | - Derek F Harris
- Department of Chemistry and Biochemistry, Utah State UniversityLoganUnited States
| | - Alex J Rivier
- Department of Bacteriology, University of Wisconsin–MadisonMadisonUnited States
| | - Brooke M Carruthers
- Department of Bacteriology, University of Wisconsin–MadisonMadisonUnited States
| | | | - Lance C Seefeldt
- Department of Chemistry and Biochemistry, Utah State UniversityLoganUnited States
| | - Betül Kaçar
- Department of Bacteriology, University of Wisconsin–MadisonMadisonUnited States
| |
Collapse
|
26
|
Siegbahn PEM. Can the E 1 state in nitrogenase tell if there is an activation process prior to catalysis? Phys Chem Chem Phys 2023; 25:3702-3706. [PMID: 36655689 DOI: 10.1039/d2cp05642a] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Model calculations have been performed for the singly reduced ground state of Mo-nitrogenase, usually termed E1. Contradictory conclusions have been reached in two recent experimental studies. In a study based on EPR, it was concluded that there is a bridging hydride in E1, while in an X-ray study it was concluded that there is no hydride in E1. Therefore, the EPR study implies that there is an oxidation of the cofactor going from E0 to E1, the X-ray study implies a reduction. DFT methods have here been used, which have previously been benchmarked on a set of redox enzymes that led to the conclusion that the accuracy is about 3 kcal mol-1 in all cases, even for redox transitions. The methodology should therefore be adequate for resolving the question of the hydride presence in E1. As a comparison, calculations are performed on both Mo- and V-nitrogenase with the same conclusion. The conclusion from the calculations has far reaching consequences for the mechanism of nitrogenase.
Collapse
Affiliation(s)
- Per E M Siegbahn
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91, Stockholm, Sweden.
| |
Collapse
|
27
|
Threatt SD, Rees DC. Biological nitrogen fixation in theory, practice, and reality: a perspective on the molybdenum nitrogenase system. FEBS Lett 2023; 597:45-58. [PMID: 36344435 PMCID: PMC10100503 DOI: 10.1002/1873-3468.14534] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 10/30/2022] [Accepted: 10/31/2022] [Indexed: 11/09/2022]
Abstract
Nitrogenase is the sole enzyme responsible for the ATP-dependent conversion of atmospheric dinitrogen into the bioavailable form of ammonia (NH3 ), making this protein essential for the maintenance of the nitrogen cycle and thus life itself. Despite the widespread use of the Haber-Bosch process to industrially produce NH3 , biological nitrogen fixation still accounts for half of the bioavailable nitrogen on Earth. An important feature of nitrogenase is that it operates under physiological conditions, where the equilibrium strongly favours ammonia production. This biological, multielectron reduction is a complex catalytic reaction that has perplexed scientists for decades. In this review, we explore the current understanding of the molybdenum nitrogenase system based on experimental and computational research, as well as the limitations of the crystallographic, spectroscopic, and computational techniques employed. Finally, essential outstanding questions regarding the nitrogenase system will be highlighted alongside suggestions for future experimental and computational work to elucidate this essential yet elusive process.
Collapse
Affiliation(s)
- Stephanie D Threatt
- Division of Chemistry and Chemical Engineering, Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA, USA
| | - Douglas C Rees
- Division of Chemistry and Chemical Engineering, Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA, USA
| |
Collapse
|
28
|
Comparative Transcriptomics Sheds Light on Remodeling of Gene Expression during Diazotrophy in the Thermophilic Methanogen Methanothermococcus thermolithotrophicus. mBio 2022; 13:e0244322. [PMID: 36409126 PMCID: PMC9765008 DOI: 10.1128/mbio.02443-22] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Some marine thermophilic methanogens are able to perform energy-consuming nitrogen fixation despite deriving only little energy from hydrogenotrophic methanogenesis. We studied this process in Methanothermococcus thermolithotrophicus DSM 2095, a methanogenic archaeon of the order Methanococcales that contributes to the nitrogen pool in some marine environments. We successfully grew this archaeon under diazotrophic conditions in both batch and fermenter cultures, reaching the highest cell density reported so far. Diazotrophic growth depended strictly on molybdenum and, in contrast to other diazotrophs, was not inhibited by tungstate or vanadium. This suggests an elaborate control of metal uptake and a specific metal recognition system for the insertion into the nitrogenase cofactor. Differential transcriptomics of M. thermolithotrophicus grown under diazotrophic conditions with ammonium-fed cultures as controls revealed upregulation of the nitrogenase machinery, including chaperones, regulators, and molybdate importers, as well as simultaneous upregulation of an ammonium transporter and a putative pathway for nitrate and nitrite utilization. The organism thus employs multiple synergistic strategies for uptake of nitrogen nutrients during the early exponential growth phase without altering transcription levels for genes involved in methanogenesis. As a counterpart, genes coding for transcription and translation processes were downregulated, highlighting the maintenance of an intricate metabolic balance to deal with energy constraints and nutrient limitations imposed by diazotrophy. This switch in the metabolic balance included unexpected processes, such as upregulation of the CRISPR-Cas system, probably caused by drastic changes in transcription levels of putative mobile and virus-like elements. IMPORTANCE The thermophilic anaerobic archaeon M. thermolithotrophicus is a particularly suitable model organism to study the coupling of methanogenesis to diazotrophy. Likewise, its capability of simultaneously reducing N2 and CO2 into NH3 and CH4 with H2 makes it a viable target for biofuel production. We optimized M. thermolithotrophicus cultivation, resulting in considerably higher cell yields and enabling the successful establishment of N2-fixing bioreactors. Improved understanding of the N2 fixation process would provide novel insights into metabolic adaptations that allow this energy-limited extremophile to thrive under diazotrophy, for instance, by investigating its physiology and uncharacterized nitrogenase. We demonstrated that diazotrophic growth of M. thermolithotrophicus is exclusively dependent on molybdenum, and complementary transcriptomics corroborated the expression of the molybdenum nitrogenase system. Further analyses of differentially expressed genes during diazotrophy across three cultivation time points revealed insights into the response to nitrogen limitation and the coordination of core metabolic processes.
Collapse
|
29
|
Yang L, Cheng C, Zhang X, Tang C, Du K, Yang Y, Shen SC, Xu SL, Yin PF, Liang HW, Ling T. Dual-site collaboration boosts electrochemical nitrogen reduction on Ru-S-C single-atom catalyst. CHINESE JOURNAL OF CATALYSIS 2022. [DOI: 10.1016/s1872-2067(22)64136-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
30
|
Catalytic nitrogen fixation using visible light energy. Nat Commun 2022; 13:7263. [PMID: 36456553 PMCID: PMC9715552 DOI: 10.1038/s41467-022-34984-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 11/15/2022] [Indexed: 12/05/2022] Open
Abstract
The synthesis of ammonia from atmospheric dinitrogen, nitrogen fixation, is one of the essential reactions for human beings. Because the current industrial nitrogen fixation depends on dihydrogen produced from fossil fuels as raw material, the development of a nitrogen fixation reaction that relies on the energy provided by renewable energy, such as visible light, is an important research goal from the viewpoint of sustainable chemistry. Herein, we establish an iridium- and molybdenum-catalysed process for synthesizing ammonia from dinitrogen under ambient reaction conditions and visible light irradiation. In this reaction system, iridium complexes and molybdenum triiodide complexes bearing N-heterocyclic carbene-based pincer ligands act as cooperative catalysts to activate 9,10-dihydroacridine and dinitrogen, respectively. The reaction of dinitrogen with 9,10-dihydroacridine is not thermodynamically favoured, and it only takes place under visible light irradiation. Therefore, the described reaction system is one that affords visible light energy-driven ammonia formation from dinitrogen catalytically.
Collapse
|
31
|
Harris DF, Badalyan A, Seefeldt LC. Mechanistic Insights into Nitrogenase FeMo-Cofactor Catalysis through a Steady-State Kinetic Model. Biochemistry 2022; 61:2131-2137. [DOI: 10.1021/acs.biochem.2c00415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Derek F. Harris
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, United States
| | - Artavazd Badalyan
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, United States
| | - Lance C. Seefeldt
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, United States
| |
Collapse
|
32
|
Stripp ST, Duffus BR, Fourmond V, Léger C, Leimkühler S, Hirota S, Hu Y, Jasniewski A, Ogata H, Ribbe MW. Second and Outer Coordination Sphere Effects in Nitrogenase, Hydrogenase, Formate Dehydrogenase, and CO Dehydrogenase. Chem Rev 2022; 122:11900-11973. [PMID: 35849738 PMCID: PMC9549741 DOI: 10.1021/acs.chemrev.1c00914] [Citation(s) in RCA: 55] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Gases like H2, N2, CO2, and CO are increasingly recognized as critical feedstock in "green" energy conversion and as sources of nitrogen and carbon for the agricultural and chemical sectors. However, the industrial transformation of N2, CO2, and CO and the production of H2 require significant energy input, which renders processes like steam reforming and the Haber-Bosch reaction economically and environmentally unviable. Nature, on the other hand, performs similar tasks efficiently at ambient temperature and pressure, exploiting gas-processing metalloenzymes (GPMs) that bind low-valent metal cofactors based on iron, nickel, molybdenum, tungsten, and sulfur. Such systems are studied to understand the biocatalytic principles of gas conversion including N2 fixation by nitrogenase and H2 production by hydrogenase as well as CO2 and CO conversion by formate dehydrogenase, carbon monoxide dehydrogenase, and nitrogenase. In this review, we emphasize the importance of the cofactor/protein interface, discussing how second and outer coordination sphere effects determine, modulate, and optimize the catalytic activity of GPMs. These may comprise ionic interactions in the second coordination sphere that shape the electron density distribution across the cofactor, hydrogen bonding changes, and allosteric effects. In the outer coordination sphere, proton transfer and electron transfer are discussed, alongside the role of hydrophobic substrate channels and protein structural changes. Combining the information gained from structural biology, enzyme kinetics, and various spectroscopic techniques, we aim toward a comprehensive understanding of catalysis beyond the first coordination sphere.
Collapse
Affiliation(s)
- Sven T Stripp
- Freie Universität Berlin, Experimental Molecular Biophysics, Berlin 14195, Germany
| | | | - Vincent Fourmond
- Laboratoire de Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie de la Méditerranée, Institut Microbiologie, Bioénergies et Biotechnologie, CNRS, Aix Marseille Université, Marseille 13402, France
| | - Christophe Léger
- Laboratoire de Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie de la Méditerranée, Institut Microbiologie, Bioénergies et Biotechnologie, CNRS, Aix Marseille Université, Marseille 13402, France
| | - Silke Leimkühler
- University of Potsdam, Molecular Enzymology, Potsdam 14476, Germany
| | - Shun Hirota
- Nara Institute of Science and Technology, Division of Materials Science, Graduate School of Science and Technology, Nara 630-0192, Japan
| | - Yilin Hu
- Department of Molecular Biology & Biochemistry, University of California, Irvine, California 92697-3900, United States
| | - Andrew Jasniewski
- Department of Molecular Biology & Biochemistry, University of California, Irvine, California 92697-3900, United States
| | - Hideaki Ogata
- Nara Institute of Science and Technology, Division of Materials Science, Graduate School of Science and Technology, Nara 630-0192, Japan
- Hokkaido University, Institute of Low Temperature Science, Sapporo 060-0819, Japan
- Graduate School of Science, University of Hyogo, Hyogo 678-1297, Japan
| | - Markus W Ribbe
- Department of Molecular Biology & Biochemistry, University of California, Irvine, California 92697-3900, United States
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| |
Collapse
|
33
|
Winiarska A, Hege D, Gemmecker Y, Kryściak-Czerwenka J, Seubert A, Heider J, Szaleniec M. Tungsten Enzyme Using Hydrogen as an Electron Donor to Reduce Carboxylic Acids and NAD . ACS Catal 2022; 12:8707-8717. [PMID: 35874620 PMCID: PMC9295118 DOI: 10.1021/acscatal.2c02147] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Tungsten-dependent
aldehyde oxidoreductases (AORs) catalyze the
oxidation of aldehydes to acids and are the only known enzymes reducing
non-activated acids using electron donors with low redox potentials.
We report here that AOR from Aromatoleum aromaticum (AORAa) catalyzes the reduction of organic
acids not only with low-potential Eu(II) or Ti(III) complexes but
also with H2 as an electron donor. Additionally, AORAa catalyzes the H2-dependent reduction
of NAD+ or benzyl viologen. The rate of H2-dependent
NAD+ reduction equals to 10% of that of aldehyde oxidation,
representing the highest H2 turnover rate observed among
the Mo/W enzymes. As AORAa simultaneously
catalyzes the reduction of acids and NAD+, we designed
a cascade reaction utilizing a NAD(P)H-dependent alcohol dehydrogenase
to reduce organic acids to the corresponding alcohols with H2 as the only reductant. The newly discovered W-hydrogenase side activity
of AORAa may find applications in either
NADH recycling or conversion of carboxylic acids to more useful biochemicals.
Collapse
Affiliation(s)
- Agnieszka Winiarska
- Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, Kraków 30-239, Poland
| | - Dominik Hege
- Faculty of Biology, Philipps-Universität Marburg, Marburg D-35043, Germany
| | - Yvonne Gemmecker
- Faculty of Biology, Philipps-Universität Marburg, Marburg D-35043, Germany
| | - Joanna Kryściak-Czerwenka
- Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, Kraków 30-239, Poland
| | - Andreas Seubert
- Faculty of Chemistry, Philipps-Universität Marburg, Marburg D-35043, Germany
| | - Johann Heider
- Faculty of Biology, Philipps-Universität Marburg, Marburg D-35043, Germany.,Center for Synthetic Microbiology, Philipps-Universität Marburg, Marburg D-35043, Germany
| | - Maciej Szaleniec
- Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, Kraków 30-239, Poland
| |
Collapse
|
34
|
Chen Z, Liu C, Sun L, Wang T. Progress of Experimental and Computational Catalyst Design for Electrochemical Nitrogen Fixation. ACS Catal 2022. [DOI: 10.1021/acscatal.2c02629] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Zhe Chen
- Center of Artificial Photosynthesis for Solar Fuels and Department of Chemistry, School of Science, Westlake University, 18 Shilongshan Road, Hangzhou, Zhejiang Province 310024, China
- Department of Chemistry, Zhejiang University, 38 Zheda Road, Hangzhou, Zhejiang Province 310027, China
| | - Chunli Liu
- Center of Artificial Photosynthesis for Solar Fuels and Department of Chemistry, School of Science, Westlake University, 18 Shilongshan Road, Hangzhou, Zhejiang Province 310024, China
- Institute of Natural Sciences, Westlake Institute for Advanced Study, 18 Shilongshan Road, Hangzhou, Zhejiang Province 310024, China
| | - Licheng Sun
- Center of Artificial Photosynthesis for Solar Fuels and Department of Chemistry, School of Science, Westlake University, 18 Shilongshan Road, Hangzhou, Zhejiang Province 310024, China
- Institute of Natural Sciences, Westlake Institute for Advanced Study, 18 Shilongshan Road, Hangzhou, Zhejiang Province 310024, China
| | - Tao Wang
- Center of Artificial Photosynthesis for Solar Fuels and Department of Chemistry, School of Science, Westlake University, 18 Shilongshan Road, Hangzhou, Zhejiang Province 310024, China
- Institute of Natural Sciences, Westlake Institute for Advanced Study, 18 Shilongshan Road, Hangzhou, Zhejiang Province 310024, China
| |
Collapse
|
35
|
Oehlmann NN, Rebelein JG. The Conversion of Carbon Monoxide and Carbon Dioxide by Nitrogenases. Chembiochem 2022; 23:e202100453. [PMID: 34643977 PMCID: PMC9298215 DOI: 10.1002/cbic.202100453] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 10/13/2021] [Indexed: 12/02/2022]
Abstract
Nitrogenases are the only known family of enzymes that catalyze the reduction of molecular nitrogen (N2 ) to ammonia (NH3 ). The N2 reduction drives biological nitrogen fixation and the global nitrogen cycle. Besides the conversion of N2 , nitrogenases catalyze a whole range of other reductions, including the reduction of the small gaseous substrates carbon monoxide (CO) and carbon dioxide (CO2 ) to hydrocarbons. However, it remains an open question whether these 'side reactivities' play a role under environmental conditions. Nonetheless, these reactivities and particularly the formation of hydrocarbons have spurred the interest in nitrogenases for biotechnological applications. There are three different isozymes of nitrogenase: the molybdenum and the alternative vanadium and iron-only nitrogenase. The isozymes differ in their metal content, structure, and substrate-dependent activity, despite their homology. This minireview focuses on the conversion of CO and CO2 to methane and higher hydrocarbons and aims to specify the differences in activity between the three nitrogenase isozymes.
Collapse
Affiliation(s)
- Niels N. Oehlmann
- Max Planck Institute for Terrestrial MicrobiologyKarl-von-Frisch-Straße 1035043MarburgGermany
| | - Johannes G. Rebelein
- Max Planck Institute for Terrestrial MicrobiologyKarl-von-Frisch-Straße 1035043MarburgGermany
| |
Collapse
|
36
|
Tran DB, To TH, Tran PD. Mo- and W-molecular catalysts for the H2 evolution, CO2 reduction and N2 fixation. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2021.214400] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
37
|
Lukoyanov DA, Harris DF, Yang ZY, Pérez-González A, Dean DR, Seefeldt LC, Hoffman BM. The One-Electron Reduced Active-Site FeFe-Cofactor of Fe-Nitrogenase Contains a Hydride Bound to a Formally Oxidized Metal-Ion Core. Inorg Chem 2022; 61:5459-5464. [PMID: 35357830 DOI: 10.1021/acs.inorgchem.2c00180] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The nitrogenase active-site cofactor must accumulate 4e-/4H+ (E4(4H) state) before N2 can bind and be reduced. Earlier studies demonstrated that this E4(4H) state stores the reducing-equivalents as two hydrides, with the cofactor metal-ion core formally at its resting-state redox level. This led to the understanding that N2 binding is mechanistically coupled to reductive-elimination of the two hydrides that produce H2. The state having acquired 2e-/2H+ (E2(2H)) correspondingly contains one hydride with a resting-state core redox level. How the cofactor accommodates addition of the first e-/H+ (E1(H) state) is unknown. The Fe-nitrogenase FeFe-cofactor was used to address this question because it is EPR-active in the E1(H) state, unlike the FeMo-cofactor of Mo-nitrogenase, thus allowing characterization by EPR spectroscopy. The freeze-trapped E1(H) state of Fe-nitrogenase shows an S = 1/2 EPR spectrum with g = [1.965, 1.928, 1.779]. This state is photoactive, and under 12 K cryogenic intracavity, 450 nm photolysis converts to a new and likewise photoactive S = 1/2 state (denoted E1(H)*) with g = [2.009, 1.950, 1.860], which results in a photostationary state, with E1(H)* relaxing to E1(H) at temperatures above 145 K. An H/D kinetic isotope effect of 2.4 accompanies the 12 K E1(H)/E1(H)* photointerconversion. These observations indicate that the addition of the first e-/H+ to the FeFe-cofactor of Fe-nitrogenase produces an Fe-bound hydride, not a sulfur-bound proton. As a result, the cluster metal-ion core is formally one-electron oxidized relative to the resting state. It is proposed that this behavior applies to all three nitrogenase isozymes.
Collapse
Affiliation(s)
- Dmitriy A Lukoyanov
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - 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
| | - Ana Pérez-González
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, United States
| | - Dennis R Dean
- Department of Biochemistry, Virginia Polytechnic Institute and State University, 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
|
38
|
Pérez‐González A, Jimenez‐Vicente E, Salinero‐Lanzarote A, Harris DF, Seefeldt LC, Dean DR. AnfO
controls fidelity of nitrogenase
FeFe
protein maturation by preventing misincorporation of
FeV
‐cofactor. Mol Microbiol 2022; 117:1080-1088. [PMID: 35220629 PMCID: PMC9310841 DOI: 10.1111/mmi.14890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 02/22/2022] [Accepted: 02/23/2022] [Indexed: 11/26/2022]
Abstract
Azotobacter vinelandii produces three genetically distinct, but structurally and mechanistically similar nitrogenase isozymes designated as Mo‐dependent, V‐dependent, or Fe‐only based on the heterometal contained within their associated active site cofactors. These catalytic cofactors, which provide the site for N2 binding and reduction, are, respectively, designated as FeMo‐cofactor, FeV‐cofactor, and FeFe‐cofactor. Fe‐only nitrogenase is a poor catalyst for N2 fixation, when compared to the Mo‐dependent and V‐dependent nitrogenases and is only produced when neither Mo nor V is available. Under conditions favoring the production of Fe‐only nitrogenase a gene product designated AnfO preserves the fidelity of Fe‐only nitrogenase by preventing the misincorporation of FeV‐cofactor, which results in the accumulation of a hybrid enzyme that cannot reduce N2. These results are interpreted to indicate that AnfO controls the fidelity of Fe‐only nitrogenase maturation during the physiological transition from conditions that favor V‐dependent nitrogenase utilization to Fe‐only nitrogenase utilization to support diazotrophic growth.
Collapse
Affiliation(s)
| | | | - Alvaro Salinero‐Lanzarote
- 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
| | - Derek F. Harris
- Department of Chemistry and Biochemistry Utah State University Logan UT USA
| | - Lance C. Seefeldt
- Department of Chemistry and Biochemistry Utah State University Logan UT USA
| | - Dennis R. Dean
- Department of Biochemistry, Virginia Tech, Blacksburg Virginia USA
| |
Collapse
|
39
|
Darnajoux R, Bradley R, Bellenger JP. In Vivo Temperature Dependency of Molybdenum and Vanadium Nitrogenase Activity in the Heterocystous Cyanobacteria Anabaena variabilis. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:2760-2769. [PMID: 35073047 DOI: 10.1021/acs.est.1c05279] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The reduction of atmospheric dinitrogen by nitrogenase is a key component of terrestrial nitrogen cycling. Nitrogenases exist in several isoforms named after the metal present within their active center: the molybdenum (Mo), the vanadium (V), and the iron (Fe)-only nitrogenase. While earlier in vitro studies hint that the relative contribution of V nitrogenase to total BNF could be temperature-dependent, the effect of temperature on in vivo activity remains to be investigated. In this study, we characterize the in vivo effect of temperature (3-42 °C) on the activities of Mo nitrogenase and V nitrogenase in the heterocystous cyanobacteria Anabaena variabilis ATTC 29413 using the acetylene reduction assay by cavity ring-down absorption spectroscopy. We demonstrate that V nitrogenase becomes as efficient as Mo nitrogenase at temperatures below 10-15 °C. At temperatures above 22 °C, BNF seems to be limited by O2 availability to respiration in both enzymes. Furthermore, Anabaena variabilis cultures grown in Mo or V media achieved similar growth rates at temperatures below 20 °C. Considering the average temperature on earth is 15 °C, our findings further support the role of V nitrogenase as a viable backup enzymatic system for BNF in natural ecosystems.
Collapse
Affiliation(s)
- Romain Darnajoux
- Département de Chimie, Université de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada
- Département de Biologie, Université de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada
- Centre Sève, Université de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada
| | - Robert Bradley
- Département de Biologie, Université de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada
- Centre Sève, Université de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada
| | - Jean-Philippe Bellenger
- Département de Chimie, Université de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada
- Centre Sève, Université de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada
| |
Collapse
|
40
|
Yuan C, Jin WT, Zhou ZH. Statistical analysis of P N clusters in Mo/VFe protein crystals using a bond valence method toward their electronic structures. RSC Adv 2022; 12:5214-5224. [PMID: 35425536 PMCID: PMC8981338 DOI: 10.1039/d1ra08507g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Accepted: 01/26/2022] [Indexed: 11/21/2022] Open
Abstract
Nowadays, large numbers of MoFe proteins have been reported and their crystal data obtained by X-ray crystallography and uploaded to the Protein Data Bank (PDB). By big data analysis using a bond valence method, we make conclusions based on 79 selected PN in all 119 P-clusters of 53 MoFe proteins and 10 P-clusters of 5 VFe proteins from all deposited crystallographic data of the PDB. In the condition of MoFe protein crystals, the resting state PN clusters are proposed to have the formal oxidation state of 2Fe(iii)6Fe(ii), hiding two oxidized electron holes with high electron delocalization. The calculations show that Fe1, Fe2, Fe5, Fe6 and Fe7 perform unequivocally as Fe2+, and Fe3 is remarkably prone to Fe(iii), while Fe4 and Fe8 have different degrees of mixed valences. For PN clusters in VFe protein crystals, Fe1, Fe2, Fe4, Fe5 and Fe6 tend to be Fe2+, but the electron distributions rearrange with Fe7 and Fe8 being more oxidized mixed valences, and Fe3 presenting a little more reductive mixed valence than that in MoFe proteins. In terms of spatial location, Fe3 and Fe6 in P-clusters of MoFe proteins are calculated as the most oxidized and reduced irons, which have the shortest distances from homocitrate in the FeMo-cofactor and [Fe4S4] cluster, respectively, and thus could function as potential electron transport sites. This work shows different electron distributions of PN clusters in Mo/VFe protein crystals, from those obtained from previous data from solution with excess reducing agent from which it was concluded that PN clusters are all ferrous according to Mössbauer and electron paramagnetic resonance spectra.
Collapse
Affiliation(s)
- Chang Yuan
- State Key Laboratory for Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University Xiamen 361005 P. R. China
| | - Wan-Ting Jin
- State Key Laboratory for Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University Xiamen 361005 P. R. China
| | - Zhao-Hui Zhou
- State Key Laboratory for Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University Xiamen 361005 P. R. China
| |
Collapse
|
41
|
Xie Z, Yuan C, Jin W, Zhou Z. Mixed‐Ligand Oxidovanadium(IV/V) Complexes Chelated by α‐Hydroxycarboxylate and 2‐(1H‐Imidazol‐2‐yl)pyridine: Localized Structures and Gas Adsorption. Eur J Inorg Chem 2021. [DOI: 10.1002/ejic.202100877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Zhen‐Lang Xie
- State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 Fujian China
| | - Chang Yuan
- State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 Fujian China
| | - Wan‐Tin Jin
- State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 Fujian China
| | - Zhao‐Hui Zhou
- State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 Fujian China
| |
Collapse
|
42
|
Maeda I. Potential of Phototrophic Purple Nonsulfur Bacteria to Fix Nitrogen in Rice Fields. Microorganisms 2021; 10:microorganisms10010028. [PMID: 35056477 PMCID: PMC8777916 DOI: 10.3390/microorganisms10010028] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 12/21/2021] [Accepted: 12/22/2021] [Indexed: 11/17/2022] Open
Abstract
Biological nitrogen fixation catalyzed by Mo-nitrogenase of symbiotic diazotrophs has attracted interest because its potential to supply plant-available nitrogen offers an alternative way of using chemical fertilizers for sustainable agriculture. Phototrophic purple nonsulfur bacteria (PNSB) diazotrophically grow under light anaerobic conditions and can be isolated from photic and microaerobic zones of rice fields. Therefore, PNSB as asymbiotic diazotrophs contribute to nitrogen fixation in rice fields. An attempt to measure nitrogen in the oxidized surface layer of paddy soil estimates that approximately 6–8 kg N/ha/year might be accumulated by phototrophic microorganisms. Species of PNSB possess one of or both alternative nitrogenases, V-nitrogenase and Fe-nitrogenase, which are found in asymbiotic diazotrophs, in addition to Mo-nitrogenase. The regulatory networks control nitrogenase activity in response to ammonium, molecular oxygen, and light irradiation. Laboratory and field studies have revealed effectiveness of PNSB inoculation to rice cultures on increases of nitrogen gain, plant growth, and/or grain yield. In this review, properties of the nitrogenase isozymes and regulation of nitrogenase activities in PNSB are described, and research challenges and potential of PNSB inoculation to rice cultures are discussed from a viewpoint of their applications as nitrogen biofertilizer.
Collapse
Affiliation(s)
- Isamu Maeda
- Department of Applied Biological Chemistry, School of Agriculture, Utsunomiya University, 350 Minemachi, Utsunomiya 321-8505, Japan
| |
Collapse
|
43
|
Structural analysis of the reductase component AnfH of iron-only nitrogenase from Azotobacter vinelandii. J Inorg Biochem 2021; 227:111690. [PMID: 34929539 DOI: 10.1016/j.jinorgbio.2021.111690] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 11/29/2021] [Accepted: 12/03/2021] [Indexed: 11/20/2022]
Abstract
Biological nitrogen fixation, the conversion of atmospheric dinitrogen into bioavailable ammonium, is exclusively catalyzed by the enzyme nitrogenase that is present in nitrogen-fixing organisms, the diazotrophs. So far, three different nitrogenase variants, encoded in their corresponding, distinct gene clusters, have been found in nature. Each one of these consists of a catalytic dinitrogenase component and a unique, ATP-dependent reductase, the Fe protein. The three variant nitrogenases differ in the composition of the active site and contain either molybdenum, vanadium or only iron in the dinitrogenase component. Here we present the 2.0 Å resolution crystal structure of the ADP-bound reductase component AnfH of the iron-only nitrogenase from the model diazotroph Azotobacter vinelandii. A comparison of this structure with the ones reported for the two other Fe protein homologs NifH and VnfH in the ADP-bound state shows that all are adopting the same conformation. However, cross-reactivity assays with the three nitrogenase homologs revealed AnfH to be compatible with iron-only nitrogenase and to a lesser degree with the vanadium-containing enzyme, but not with molybdenum nitrogenase.
Collapse
|
44
|
Spiller N, Bjornsson R, DeBeer S, Neese F. Carbon Monoxide Binding to the Iron-Molybdenum Cofactor of Nitrogenase: a Detailed Quantum Mechanics/Molecular Mechanics Investigation. Inorg Chem 2021; 60:18031-18047. [PMID: 34767349 PMCID: PMC8653219 DOI: 10.1021/acs.inorgchem.1c02649] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Carbon monoxide (CO) is a well-known inhibitor of nitrogenase activity. Under turnover conditions, CO binds to FeMoco, the active site of Mo nitrogenase. Time-resolved IR measurements suggest an initial terminal CO at 1904 cm-1 that converts to a bridging CO at 1715 cm-1, and an X-ray structure shows that CO can displace one of the bridging belt sulfides of FeMoco. However, the CO-binding redox state(s) of FeMoco (En) and the role of the protein environment in stabilizing specific CO-bound intermediates remain elusive. In this work, we carry out an in-depth analysis of the CO-FeMoco interaction based on quantum chemical calculations addressing different aspects of the electronic structure. (1) The local electronic structure of the Fe-CO bond is studied through diamagnetically substituted FeMoco. (2) A cluster model of FeMoco within a polarizable continuum illustrates how CO binding may affect the spin-coupling between the metal centers. (3) A QM/MM model incorporates the explicit influence of the amino acid residues surrounding FeMoco in the MoFe protein. The QM/MM model predicts both a terminal and a bridging CO in the E1 redox state. The scaled calculated CO frequencies (1922 and 1716 cm-1, respectively) are in good agreement with the experimentally observed IR bands supporting CO binding to the E1 state. Alternatively, an E2 state QM/MM model, which has the same atomic structure as the CO-bound X-ray structure, features a semi-bridging CO with a scaled calculated frequency (1718 cm-1) similar to the bridging CO in the E1 model.
Collapse
Affiliation(s)
- Nico Spiller
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Ragnar Bjornsson
- Max Planck Institute for Chemical Energy Conversion, Stiftstr 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Serena DeBeer
- Max Planck Institute for Chemical Energy Conversion, Stiftstr 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Frank Neese
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| |
Collapse
|
45
|
Pessoa JC, Santos MF, Correia I, Sanna D, Sciortino G, Garribba E. Binding of vanadium ions and complexes to proteins and enzymes in aqueous solution. Coord Chem Rev 2021. [DOI: 10.1016/j.ccr.2021.214192] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
|
46
|
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
|
47
|
Wilson ST, Caffin M, White AE, Karl DM. Evaluation of argon-induced hydrogen production as a method to measure nitrogen fixation by cyanobacteria. JOURNAL OF PHYCOLOGY 2021; 57:863-873. [PMID: 33450056 DOI: 10.1111/jpy.13129] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Revised: 11/14/2020] [Accepted: 11/23/2020] [Indexed: 06/12/2023]
Abstract
The production of dihydrogen (H2 ) is an enigmatic yet obligate component of biological dinitrogen (N2 ) fixation. This study investigates the effect on H2 production by N2 fixing cyanobacteria when they are exposed to either air or a gas mixture consisting of argon, oxygen, and carbon dioxide (Ar:O2 :CO2 ). In the absence of N2 , nitrogenase diverts the flow of electrons to the production of H2 , which becomes a measure of Total Nitrogenase Activity (TNA). This method of argon-induced hydrogen production (AIHP) is much less commonly used to infer rates of N2 fixation than the acetylene reduction (AR) assay. We provide here a full evaluation of the AIHP method and demonstrate its ability to achieve high-resolution measurements of TNA in a gas exchange flow-through system. Complete diel profiles of H2 production were obtained for N2 fixing cyanobacteria despite the absence of N2 that broadly reproduced the temporal patterns observed by the AR assay. Comparison of H2 production under air versus Ar:O2 :CO2 revealed the efficiency of electron usage during N2 fixation and place these findings in the broader context of cell metabolism. Ultimately, AIHP is demonstrated to be a viable alternative to the AR assay with several additional merits that provide an insight into cell physiology and promise for successful field application.
Collapse
Affiliation(s)
- Samuel T Wilson
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education (C-MORE), University of Hawai'i at Manoa, Honolulu, Hawai'i, USA
| | - Mathieu Caffin
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education (C-MORE), University of Hawai'i at Manoa, Honolulu, Hawai'i, USA
| | - Angelicque E White
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education (C-MORE), University of Hawai'i at Manoa, Honolulu, Hawai'i, USA
| | - David M Karl
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education (C-MORE), University of Hawai'i at Manoa, Honolulu, Hawai'i, USA
| |
Collapse
|
48
|
Rohde M, Laun K, Zebger I, Stripp ST, Einsle O. Two ligand-binding sites in CO-reducing V nitrogenase reveal a general mechanistic principle. SCIENCE ADVANCES 2021; 7:7/22/eabg4474. [PMID: 34049880 PMCID: PMC8163085 DOI: 10.1126/sciadv.abg4474] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 04/14/2021] [Indexed: 06/12/2023]
Abstract
Besides its role in biological nitrogen fixation, vanadium-containing nitrogenase also reduces carbon monoxide (CO) to hydrocarbons, in analogy to the industrial Fischer-Tropsch process. The protein yields 93% of ethylene (C2H4), implying a C-C coupling step that mandates the simultaneous binding of two CO at the active site FeV cofactor. Spectroscopic data indicated multiple CO binding events, but structural analyses of Mo and V nitrogenase only confirmed a single site. Here, we report the structure of a two CO-bound state of V nitrogenase at 1.05 Å resolution, with one μ-bridging and one terminal CO molecule. This additional, specific ligand binding site suggests a mechanistic route for CO reduction and hydrocarbon formation, as well as a second access pathway for protons required during the reaction. Moreover, carbonyls are strong-field ligands that are chemically similar to mechanistically relevant hydrides that may be formed and used in a fully analogous fashion.
Collapse
Affiliation(s)
- Michael Rohde
- Institute for Biochemistry, University of Freiburg, Albertstrasse 21, 79104 Freiburg, Germany
| | - Konstantin Laun
- Institute of Chemistry, Technical University of Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany
| | - Ingo Zebger
- Institute of Chemistry, Technical University of Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany
| | - Sven T Stripp
- Institute of Experimental Physics, Department of Physics, Free University of Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Oliver Einsle
- Institute for Biochemistry, University of Freiburg, Albertstrasse 21, 79104 Freiburg, Germany.
| |
Collapse
|
49
|
Tanabe Y, Nishibayashi Y. Comprehensive insights into synthetic nitrogen fixation assisted by molecular catalysts under ambient or mild conditions. Chem Soc Rev 2021; 50:5201-5242. [PMID: 33651046 DOI: 10.1039/d0cs01341b] [Citation(s) in RCA: 64] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
N2 is fixed as NH3 industrially by the Haber-Bosch process under harsh conditions, whereas biological nitrogen fixation is achieved under ambient conditions, which has prompted development of alternative methods to fix N2 catalyzed by transition metal molecular complexes. Since the early 21st century, catalytic conversion of N2 into NH3 under ambient conditions has been achieved by using molecular catalysts, and now H2O has been utilized as a proton source with turnover frequencies reaching the values found for biological nitrogen fixation. In this review, recent advances in the development of molecular catalysts for synthetic N2 fixation under ambient or mild conditions are summarized, and potential directions for future research are also discussed.
Collapse
Affiliation(s)
- Yoshiaki Tanabe
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
| | - Yoshiaki Nishibayashi
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
| |
Collapse
|
50
|
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
|