1
|
Li Y, Liu Q, Zhang DX, Zhang ZY, Xu A, Jiang YL, Chen ZC. Metal nutrition and transport in the process of symbiotic nitrogen fixation. PLANT COMMUNICATIONS 2024; 5:100829. [PMID: 38303509 PMCID: PMC11009365 DOI: 10.1016/j.xplc.2024.100829] [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: 09/28/2023] [Revised: 01/14/2024] [Accepted: 01/26/2024] [Indexed: 02/03/2024]
Abstract
Symbiotic nitrogen fixation (SNF) facilitated by the interaction between legumes and rhizobia is a well-documented and eco-friendly alternative to chemical nitrogen fertilizers. Host plants obtain fixed nitrogen from rhizobia by providing carbon and mineral nutrients. These mineral nutrients, which are mostly in the form of metal ions, are implicated in various stages of the SNF process. This review describes the functional roles played by metal ions in nodule formation and nitrogen fixation and specifically addresses their transport mechanisms and associated transporters within root nodules. Future research directions and potential strategies for enhancing SNF efficiency are also discussed.
Collapse
Affiliation(s)
- Yuan Li
- Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Qian Liu
- Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Dan-Xun Zhang
- Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Zhuo-Yan Zhang
- Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Ao Xu
- Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Yuan-Long Jiang
- Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Zhi-Chang Chen
- Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| |
Collapse
|
2
|
Abstract
The Fischer-Tropsch (FT) process converts a mixture of CO and H2 into liquid hydrocarbons as a major component of the gas-to-liquid technology for the production of synthetic fuels. Contrary to the energy-demanding chemical FT process, the enzymatic FT-type reactions catalyzed by nitrogenase enzymes, their metalloclusters, and synthetic mimics utilize H+ and e- as the reducing equivalents to reduce CO, CO2, and CN- into hydrocarbons under ambient conditions. The C1 chemistry exemplified by these FT-type reactions is underscored by the structural and electronic properties of the nitrogenase-associated metallocenters, and recent studies have pointed to the potential relevance of this reactivity to nitrogenase mechanism, prebiotic chemistry, and biotechnological applications. This review will provide an overview of the features of nitrogenase enzymes and associated metalloclusters, followed by a detailed discussion of the activities of various nitrogenase-derived FT systems and plausible mechanisms of the enzymatic FT reactions, highlighting the versatility of this unique reactivity while providing perspectives onto its mechanistic, evolutionary, and biotechnological implications.
Collapse
Affiliation(s)
- Yilin Hu
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine 92697-3900, USA
| | - Chi Chung Lee
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine 92697-3900, USA
| | - Mario Grosch
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine 92697-3900, USA
| | - Joseph B. Solomon
- Department of Chemistry, University of California, Irvine, CA 92697-2025, USA
| | - Wolfgang Weigand
- Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Markus W. Ribbe
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine 92697-3900, USA
- Department of Chemistry, University of California, Irvine, CA 92697-2025, USA
| |
Collapse
|
3
|
Cao HR, Peng WT, Nie MM, Bai S, Chen CQ, Liu Q, Guo ZL, Liao H, Chen ZC. Carbon-nitrogen trading in symbiotic nodules depends on magnesium import. Curr Biol 2022; 32:4337-4349.e5. [PMID: 36055239 DOI: 10.1016/j.cub.2022.08.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 06/22/2022] [Accepted: 08/10/2022] [Indexed: 11/26/2022]
Abstract
Symbiotic nitrogen fixation provides large amounts of nitrogen for global agricultural systems with little environmental or economic costs. The basis of symbiosis is the nutrient exchange occurring between legumes and rhizobia, but key regulators controlling nutrient exchange are largely unknown. Here, we reveal that magnesium (Mg), an important nutrient factor that preferentially accumulates in inner cortical cells of soybean nodules, shows the most positive correlation with nodule carbon (C) import and nitrogen (N) export. We further identified a pair of Mg transporter genes, GmMGT4 and GmMGT5, that are specifically expressed in the nodule cortex, modulating both nodule Mg import and C-N transport processes. The GmMGT4&5-dependent Mg import activates the activity of a plasmodesmata-located β-1,3-glucanase GmBG2 and consequently keeps plasmodesmata permeable for C-N transport in nodule inner cortical cells. Our studies discovered an important regulating pathway for host plants fine-tuning nodule C-N trading to achieve optimal growth, which may be helpful for optimizing nutrient management for soybean production.
Collapse
Affiliation(s)
- Hong-Rui Cao
- Root Biology Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Wen-Ting Peng
- Root Biology Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Miao-Miao Nie
- Root Biology Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Shuang Bai
- Root Biology Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Chun-Qu Chen
- Root Biology Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Qian Liu
- College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Zi-Long Guo
- Root Biology Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Hong Liao
- Root Biology Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Zhi-Chang Chen
- Root Biology Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| |
Collapse
|
4
|
Jasniewski AJ, Lee CC, Ribbe MW, Hu Y. Reactivity, Mechanism, and Assembly of the Alternative Nitrogenases. Chem Rev 2020; 120:5107-5157. [PMID: 32129988 DOI: 10.1021/acs.chemrev.9b00704] [Citation(s) in RCA: 107] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Biological nitrogen fixation is catalyzed by the enzyme nitrogenase, which facilitates the cleavage of the relatively inert triple bond of N2. Nitrogenase is most commonly associated with the molybdenum-iron cofactor called FeMoco or the M-cluster, and it has been the subject of extensive structural and spectroscopic characterization over the past 60 years. In the late 1980s and early 1990s, two "alternative nitrogenase" systems were discovered, isolated, and found to incorporate V or Fe in place of Mo. These systems are regulated by separate gene clusters; however, there is a high degree of structural and functional similarity between each nitrogenase. Limited studies with the V- and Fe-nitrogenases initially demonstrated that these enzymes were analogously active as the Mo-nitrogenase, but more recent investigations have found capabilities that are unique to the alternative systems. In this review, we will discuss the reactivity, biosynthetic, and mechanistic proposals for the alternative nitrogenases as well as their electronic and structural properties in comparison to the well-characterized Mo-dependent system. Studies over the past 10 years have been particularly fruitful, though key aspects about V- and Fe-nitrogenases remain unexplored.
Collapse
Affiliation(s)
- Andrew J Jasniewski
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697-3900, United States
| | - Chi Chung Lee
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697-3900, United States
| | - Markus W Ribbe
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697-3900, United States.,Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - Yilin Hu
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697-3900, United States
| |
Collapse
|
5
|
Zanello P. Structure and electrochemistry of proteins harboring iron-sulfur clusters of different nuclearities. Part V. Nitrogenases. Coord Chem Rev 2019. [DOI: 10.1016/j.ccr.2019.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
6
|
Grossman JD, Camire EJ, Glynn CA, Neil CM, Seguinot BO, Perlstein DL. The Cfd1 Subunit of the Nbp35-Cfd1 Iron Sulfur Cluster Scaffolding Complex Controls Nucleotide Binding. Biochemistry 2019; 58:1587-1595. [PMID: 30785732 DOI: 10.1021/acs.biochem.8b00798] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The cytosolic iron sulfur cluster assembly (CIA) scaffold biosynthesizes iron sulfur cluster cofactors for enzymes residing in the cytosol and the nucleus. In fungi and animals, it comprises two homologous ATPases, called Nbp35 and Cfd1 in yeast, which can form homodimeric and heterodimeric complexes. Both proteins are required for CIA function, but their individual roles are not well understood. Here we investigate the nucleotide affinity of each form of the scaffold for ATP and ADP to reveal any differences that could shed light on the functions of the different oligomeric forms of the protein or any distinct roles of the individual subunits. All forms of the CIA scaffold are specific for adenosine nucleotides and not guanosine nucleotides. Although the Cfd1 homodimer has no detectable ATPase activity, it binds ATP with an affinity comparable to that of the hydrolysis competent forms, Nbp352 and Nbp35-Cfd1. Titrations to determine the number of nucleotide binding sites combined with site-directed mutagenesis demonstrate that the nucleotide must bind to the Cfd1 subunit of the heterodimer before it can bind to Nbp35 and that the Cfd1 subunit is hydrolysis competent when bound to Nbp35 in the heterodimer. Altogether, our work reveals the distinct roles of the Nbp35 and Cfd1 subunits in their heterodimeric complex. Cfd1 controls nucleotide binding, and the Nbp35 subunit is required to activate nucleotide hydrolysis.
Collapse
Affiliation(s)
- John D Grossman
- Department of Chemistry , Boston University , Boston , Massachusetts 02215 , United States
| | - Eric J Camire
- Department of Chemistry , Boston University , Boston , Massachusetts 02215 , United States
| | - Calina A Glynn
- Department of Chemistry , Boston University , Boston , Massachusetts 02215 , United States
| | - Christopher M Neil
- Department of Chemistry , Boston University , Boston , Massachusetts 02215 , United States
| | - Bryan O Seguinot
- Department of Chemistry , Boston University , Boston , Massachusetts 02215 , United States
| | - Deborah L Perlstein
- Department of Chemistry , Boston University , Boston , Massachusetts 02215 , United States
| |
Collapse
|
7
|
Abstract
Although the nitrogen-fixing enzyme nitrogenase critically requires both a reductase component (Fe protein) and a catalytic component, considerably more work has focused on the latter species. Properties of the catalytic component, which contains two highly complex metallocofactors and catalyzes the reduction of N2 into ammonia, understandably making it the “star” of nitrogenase. However, as its obligate redox partner, the Fe protein is a workhorse with multiple supporting roles in both cofactor maturation and catalysis. In particular, the nitrogenase Fe protein utilizes nucleotide binding and hydrolysis in concert with electron transfer to accomplish several tasks of critical importance. Aside from the ATP-coupled transfer of electrons to the catalytic component during substrate reduction, the Fe protein also functions in a maturase and insertase capacity to facilitate the biosynthesis of the two-catalytic component metallocofactors: fusion of the [Fe8S7] P-cluster and insertion of Mo and homocitrate to form the matured [(homocitrate)MoFe7S9C] M-cluster. These and key structural-functional relationships of the indispensable Fe protein and its complex with the catalytic component will be covered in this review.
Collapse
|
8
|
Artz JH, Zadvornyy OA, Mulder DW, King PW, Peters JW. Structural Characterization of Poised States in the Oxygen Sensitive Hydrogenases and Nitrogenases. Methods Enzymol 2017; 595:213-259. [PMID: 28882202 DOI: 10.1016/bs.mie.2017.07.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The crystallization of FeS cluster-containing proteins has been challenging due to their oxygen sensitivity, and yet these enzymes are involved in many critical catalytic reactions. The last few years have seen a wealth of innovative experiments designed to elucidate not just structural but mechanistic insights into FeS cluster enzymes. Here, we focus on the crystallization of hydrogenases, which catalyze the reversible reduction of protons to hydrogen, and nitrogenases, which reduce dinitrogen to ammonia. A specific focus is given to the different experimental parameters and strategies that are used to trap distinct enzyme states, specifically, oxidants, reductants, and gas treatments. Other themes presented here include the recent use of Cryo-EM, and how coupling various spectroscopies to crystallization is opening up new approaches for structural and mechanistic analysis.
Collapse
Affiliation(s)
- Jacob H Artz
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States
| | - Oleg A Zadvornyy
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States
| | - David W Mulder
- National Renewable Energy Laboratory, Biosciences Center, Golden, CO, United States
| | - Paul W King
- National Renewable Energy Laboratory, Biosciences Center, Golden, CO, United States
| | - John W Peters
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States.
| |
Collapse
|
9
|
Pence N, Tokmina-Lukaszewska M, Yang ZY, Ledbetter RN, Seefeldt LC, Bothner B, Peters JW. Unraveling the interactions of the physiological reductant flavodoxin with the different conformations of the Fe protein in the nitrogenase cycle. J Biol Chem 2017; 292:15661-15669. [PMID: 28784660 DOI: 10.1074/jbc.m117.801548] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2017] [Revised: 08/02/2017] [Indexed: 01/21/2023] Open
Abstract
Nitrogenase reduces dinitrogen (N2) to ammonia in biological nitrogen fixation. The nitrogenase Fe protein cycle involves a transient association between the reduced, MgATP-bound Fe protein and the MoFe protein and includes electron transfer, ATP hydrolysis, release of Pi, and dissociation of the oxidized, MgADP-bound Fe protein from the MoFe protein. The cycle is completed by reduction of oxidized Fe protein and nucleotide exchange. Recently, a kinetic study of the nitrogenase Fe protein cycle involving the physiological reductant flavodoxin reported a major revision of the rate-limiting step from MoFe protein and Fe protein dissociation to release of Pi Because the Fe protein cannot interact with flavodoxin and the MoFe protein simultaneously, knowledge of the interactions between flavodoxin and the different nucleotide states of the Fe protein is critically important for understanding the Fe protein cycle. Here we used time-resolved limited proteolysis and chemical cross-linking to examine nucleotide-induced structural changes in the Fe protein and their effects on interactions with flavodoxin. Differences in proteolytic cleavage patterns and chemical cross-linking patterns were consistent with known nucleotide-induced structural differences in the Fe protein and indicated that MgATP-bound Fe protein resembles the structure of the Fe protein in the stabilized nitrogenase complex structures. Docking models and cross-linking patterns between the Fe protein and flavodoxin revealed that the MgADP-bound state of the Fe protein has the most complementary docking interface with flavodoxin compared with the MgATP-bound state. Together, these findings provide new insights into the control mechanisms in protein-protein interactions during the Fe protein cycle.
Collapse
Affiliation(s)
- Natasha Pence
- From the Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164.,the Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, and
| | | | - Zhi-Yong Yang
- the Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322
| | - Rhesa N Ledbetter
- the Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322
| | - Lance C Seefeldt
- the Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322
| | - Brian Bothner
- the Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, and
| | - John W Peters
- From the Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164, .,the Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, and
| |
Collapse
|
10
|
Chen K, Wang D, Kurgan L. Systematic investigation of sequence and structural motifs that recognize ATP. Comput Biol Chem 2015; 56:131-41. [PMID: 25935117 DOI: 10.1016/j.compbiolchem.2015.04.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 04/05/2015] [Accepted: 04/18/2015] [Indexed: 02/07/2023]
Abstract
Interaction between ATP, a multifunctional and ubiquitous nucleotide, and proteins initializes phosphorylation, polypeptide synthesis and ATP hydrolysis which supplies energy for metabolism. However, current knowledge concerning the mechanisms through which ATP is recognized by proteins is incomplete, scattered, and inaccurate. We systemically investigate sequence and structural motifs of proteins that recognize ATP. We identified three novel motifs and refined the known p-loop and class II aminoacyl-tRNA synthetase motifs. The five motifs define five distinct ATP-protein interaction modes which concern over 5% of known protein structures. We demonstrate that although these motifs share a common GXG tripeptide they recognize ATP through different functional groups. The p-loop motif recognizes ATP through phosphates, class II aminoacyl-tRNA synthetase motif targets adenosine and the other three motifs recognize both phosphates and adenosine. We show that some motifs are shared by different enzyme types. Statistical tests demonstrate that the five sequence motifs are significantly associated with the nucleotide binding proteins. Large-scale test on PDB reveals that about 98% of proteins that include one of the structural motifs are confirmed to bind ATP.
Collapse
Affiliation(s)
- Ke Chen
- School of Computer Science and Software Engineering, Tianjin Polytechnic University, Tianjin 300387, China.
| | - Dacheng Wang
- School of Computer Science and Software Engineering, Tianjin Polytechnic University, Tianjin 300387, China
| | - Lukasz Kurgan
- Department of Electrical and Computer Engineering, 2nd floor, ECERF (9107 116 Street), University of Alberta, Edmonton, AB T6G 2V4, Canada
| |
Collapse
|
11
|
Liu J, Chakraborty S, Hosseinzadeh P, Yu Y, Tian S, Petrik I, Bhagi A, Lu Y. Metalloproteins containing cytochrome, iron-sulfur, or copper redox centers. Chem Rev 2014; 114:4366-469. [PMID: 24758379 PMCID: PMC4002152 DOI: 10.1021/cr400479b] [Citation(s) in RCA: 549] [Impact Index Per Article: 54.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Indexed: 02/07/2023]
Affiliation(s)
- Jing Liu
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Saumen Chakraborty
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Parisa Hosseinzadeh
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Yang Yu
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Shiliang Tian
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Igor Petrik
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Ambika Bhagi
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Yi Lu
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| |
Collapse
|
12
|
Hoffman BM, Lukoyanov D, Yang ZY, Dean DR, Seefeldt LC. Mechanism of nitrogen fixation by nitrogenase: the next stage. Chem Rev 2014; 114:4041-62. [PMID: 24467365 PMCID: PMC4012840 DOI: 10.1021/cr400641x] [Citation(s) in RCA: 969] [Impact Index Per Article: 96.9] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Brian M Hoffman
- Department of Chemistry and Biochemistry, Utah State University , 0300 Old Main Hill, Logan, Utah 84322, United States
| | | | | | | | | |
Collapse
|
13
|
Abstract
Nitrogenase is a globally important enzyme that catalyses the reduction of atmospheric dinitrogen into ammonia and is thus an important part of the nitrogen cycle. The nitrogenase enzyme is composed of a catalytic molybdenum-iron protein (MoFe protein) and a protein containing an [Fe4-S4] cluster (Fe protein) that functions as a dedicated ATP-dependent reductase. The current understanding of electron transfer between these two proteins is based on stopped-flow spectrophotometry, which has allowed the rates of complex formation and electron transfer to be accurately determined. Surprisingly, a total of four Fe protein molecules are required to saturate one MoFe protein molecule, despite there being only two well-characterized Fe-protein-binding sites. This has led to the conclusion that the purified Fe protein is only half-active with respect to electron transfer to the MoFe protein. Studies on the electron transfer between both proteins using rapid-quench EPR confirmed that, during pre-steady-state electron transfer, the Fe protein only becomes half-oxidized. However, stopped-flow spectrophotometry on MoFe protein that had only one active site occupied was saturated by approximately three Fe protein equivalents. These results imply that the Fe protein has a second interaction during the initial stages of mixing that is not involved in electron transfer.
Collapse
|
14
|
Mulder DW, Peters JW. Small angle x-ray scattering spectroscopy. Methods Mol Biol 2011; 766:177-189. [PMID: 21833868 DOI: 10.1007/978-1-61779-194-9_12] [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: 05/31/2023]
Abstract
Conformational changes imposed upon the Fe protein during binding and hydrolysis of Mg·ATP are key to initiating the cycle of interactions within the nitrogenase complex that result in gated electron transfer and the eventual multiple electron reduction of dinitrogen to ammonia. Wonderful insights into how nitrogenase accomplishes this have been gleaned from a number of very nice crystal structures, but conformational changes can only be inferred in a very superficial manner, and a number of key conformations relevant to fully understanding conformational changes have eluded this approach. Alternatively, small angle x-ray scattering (SAXS) has proven to be a helpful method for complimenting x-ray crystallography and determining solution structures of various nucleotide-bound states.
Collapse
Affiliation(s)
- David W Mulder
- Department of Chemistry and Biochemistry, Astrobiology Biogeocatalysis Research Center, Montana State University, Bozeman, MT 59717, USA.
| | | |
Collapse
|
15
|
Abstract
Nitrogenase is the enzyme responsible for biological reduction of dinitrogen (N(2)) to ammonia, a form usable for life. Playing a central role in the global biogeochemical nitrogen cycle, this enzyme has been the focus of intensive research for over 60 years. This chapter provides an overview of the features of nitrogenase as a background to the subsequent chapters of this volume that detail the many methods that have been applied in an attempt to gain a deeper understanding of this complex enzyme.
Collapse
Affiliation(s)
- Zhi-Yong Yang
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322, USA.
| | | | | |
Collapse
|
16
|
Abstract
Nitrogen-fixing bacteria catalyze the reduction of dinitrogen (N(2)) to two ammonia molecules (NH(3)), the major contribution of fixed nitrogen to the biogeochemical nitrogen cycle. The most widely studied nitrogenase is the molybdenum (Mo)-dependent enzyme. The reduction of N(2) by this enzyme involves the transient interaction of two component proteins, designated the iron (Fe) protein and the MoFe protein, and minimally requires 16 magnesium ATP (MgATP), eight protons, and eight electrons. The current state of knowledge on how these proteins and small molecules together effect the reduction of N(2) to ammonia is reviewed. Included is a summary of the roles of the Fe protein and MgATP hydrolysis, information on the roles of the two metal clusters contained in the MoFe protein in catalysis, insights gained from recent success in trapping substrates and inhibitors at the active-site metal cluster FeMo cofactor, and finally, considerations of the mechanism of N(2) reduction catalyzed by nitrogenase.
Collapse
Affiliation(s)
- Lance C Seefeldt
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322, USA.
| | | | | |
Collapse
|
17
|
Petersen J, Fisher K, Lowe DJ. Structural basis for VO2+ inhibition of nitrogenase activity (A): 31P and 23Na interactions with the metal at the nucleotide binding site of the nitrogenase Fe protein identified by ENDOR spectroscopy. J Biol Inorg Chem 2008; 13:623-35. [PMID: 18351402 DOI: 10.1007/s00775-008-0360-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2007] [Accepted: 02/27/2008] [Indexed: 11/30/2022]
Abstract
We previously reported the vanadyl hyperfine couplings of VO(2+)-ATP and VO(2+)-ADP complexes in the presence of the nitrogenase Fe protein from Klebsiella pneumoniae (Petersen et al. in Biochemistry 41:13253-13263, 2002). It was demonstrated that different VO(2+)-nucleotide coordination environments coexist and are distinguishable by electron paramagnetic resonance (EPR) spectroscopy. Here orientation-selective continuous-wave electron-nuclear double resonance (ENDOR) spectra have been investigated especially in the low-radio-frequency range in order to identify superhyperfine interactions with nuclei other than protons. Some of these resonances have been attributed to the presence of a strong interaction with a 31P nucleus although no resolvable superhyperfine structure due to 31P or other nuclei was detected in the EPR spectra. The superhyperfine coupling component is determined to be about 25 MHz. Such a 31P coupling is consistent with an interaction of the metal with phosphorus from a directly, equatorially coordinated nucleotide phosphate group(s). Additionally, novel more prominent 31P ENDOR signals are detected in the low-frequency region. Some of these correspond to a relatively weak 31P coupling. This coupling is present with ATP for all pH forms but is absent with ADP. The ENDOR resonances of these weakly coupled 31P are likely to originate from an interaction of the metal with a nucleotide phosphate group of the nucleoside triphosphate and are attributed to a phosphorus with axial characteristics. Another set of resonances, split about the nuclear Zeeman frequency of 23Na, was detected, suggesting that a monovalent Na+ ion is closely associated with the divalent metal-nucleotide binding site. Na+ replacement by K+ unambiguously confirmed that ENDORs at radio frequencies between 3.0 and 4.5 MHz arise from an interaction with Na+ ions. In contrast to the low-frequency 31P signal, these resonances are present in spectra with both ADP and ATP, and for both low- and neutral-pH forms, although slight differences are detected, showing that these are sensitive to the nucleotide and pH.
Collapse
Affiliation(s)
- Jan Petersen
- Department of Biological Chemistry, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK.
| | | | | |
Collapse
|
18
|
Structural basis for VO2+-inhibition of nitrogenase activity: (B) pH-sensitive inner-sphere rearrangements in the 1H-environment of the metal coordination site of the nitrogenase Fe–protein identified by ENDOR spectroscopy. J Biol Inorg Chem 2008; 13:637-50. [DOI: 10.1007/s00775-008-0364-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2007] [Accepted: 03/05/2008] [Indexed: 11/25/2022]
|
19
|
Sarma R, Mulder DW, Brecht E, Szilagyi RK, Seefeldt LC, Tsuruta H, Peters JW. Probing the MgATP-bound conformation of the nitrogenase Fe protein by solution small-angle X-ray scattering. Biochemistry 2007; 46:14058-66. [PMID: 18001132 PMCID: PMC3289971 DOI: 10.1021/bi700446s] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The MgATP-bound conformation of the Fe protein of nitrogenase from Azotobacter vinelandii has been examined in solution by small-angle X-ray scattering (SAXS) and compared to existing crystallographically characterized Fe protein conformations. The results of the analysis of the crystal structure of an Fe protein variant with a Switch II single-amino acid deletion recently suggested that the MgATP-bound state of the Fe protein may exist in a conformation that involves a large-scale reorientation of the dimer subunits, resulting in an overall elongated structure relative to the more compact structure of the MgADP-bound state. It was hypothesized that the Fe protein variant may be a conformational mimic of the MgATP-bound state of the native Fe protein largely on the basis of the observation that the spectroscopic properties of the [4Fe-4S] cluster of the variant mimicked in part the spectroscopic signatures of the native nitrogenase Fe protein in the MgATP-bound state. In this work, SAXS studies reveal that the large-scale conformational differences between the native Fe protein and the variant observed by X-ray crystallography are also observed in solution. In addition, comparison of the SAXS curves of the Fe protein nucleotide-bound states to the nucleotide-free states indicates that the conformation of the MgATP-bound state in solution does not resemble the structure of the variant as initially proposed, but rather, at the resolution of this experiment, it resembles the structure of the nucleotide-free state. These results provide insights into the Fe protein conformations that define the role of MgATP in nitrogenase catalysis.
Collapse
Affiliation(s)
- Ranjana Sarma
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717
| | - David W. Mulder
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717
| | - Eric Brecht
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717
| | - Robert K. Szilagyi
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717
| | | | | | - John W. Peters
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717
| |
Collapse
|