1
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Kang W, Mu L, Hu X. Marine Colloids Boost Nitrogen Fixation in Trichodesmium erythraeum by Photoelectrophy. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:9236-9249. [PMID: 38748855 DOI: 10.1021/acs.est.4c01849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Nitrogen fixation by the diazotrophic cyanobacterium Trichodesmium contributes up to 50% of the bioavailable nitrogen in the ocean. N2 fixation by Trichodesmium is limited by the availability of nutrients, such as iron (Fe) and phosphorus (P). Although colloids are ubiquitous in the ocean, the effects of Fe limitation on nitrogen fixation by marine colloids (MC) and the related mechanisms are largely unexplored. In this study, we found that MC exhibit photoelectrochemical properties that boost nitrogen fixation by photoelectrophy in Trichodesmium erythraeum. MC efficiently promote photosynthesis in T. erythraeum, thus enhancing its growth. Photoexcited electrons from MC are directly transferred to the photosynthetic electron transport chain and contribute to nitrogen fixation and ammonia assimilation. Transcriptomic analysis revealed that MC significantly upregulates genes related to the electron transport chain, photosystem, and photosynthesis, which is consistent with elevated photosynthetic capacities (e.g., Fv/Fm and carboxysomes). As a result, MC increase the N2 fixation rate by 67.5-89.3%. Our findings highlight a proof-of-concept electron transfer pathway by which MC boost nitrogen fixation, broadening our knowledge on the role of ubiquitous colloids in marine nitrogen biogeochemistry.
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Affiliation(s)
- Weilu Kang
- Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), Carbon Neutrality Interdisciplinary Science Centre, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Li Mu
- Tianjin Key Laboratory of Agro-Environment and Product Safety, Key Laboratory for Environmental Factors Controlling Agro-Product Quality Safety (Ministry of Agriculture and Rural Affairs), Institute of Agro-Environmental Protection, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China
| | - Xiangang Hu
- Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), Carbon Neutrality Interdisciplinary Science Centre, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
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2
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Tokmina-Lukaszewska M, Huang Q, Berry L, Kallas H, Peters JW, Seefeldt LC, Raugei S, Bothner B. Fe protein docking transduces conformational changes to MoFe nitrogenase active site in a nucleotide-dependent manner. Commun Chem 2023; 6:254. [PMID: 37980448 PMCID: PMC10657360 DOI: 10.1038/s42004-023-01046-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Accepted: 10/30/2023] [Indexed: 11/20/2023] Open
Abstract
The reduction of dinitrogen to ammonia catalyzed by nitrogenase involves a complex series of events, including ATP hydrolysis, electron transfer, and activation of metal clusters for N2 reduction. Early evidence shows that an essential part of the mechanism involves transducing information between the nitrogenase component proteins through conformational dynamics. Here, millisecond time-resolved hydrogen-deuterium exchange mass spectrometry was used to unravel peptide-level protein motion on the time scale of catalysis of Mo-dependent nitrogenase from Azotobacter vinelandii. Normal mode analysis calculations complemented this data, providing insights into the specific signal transduction pathways that relay information across protein interfaces at distances spanning 100 Å. Together, these results show that conformational changes induced by protein docking are rapidly transduced to the active site, suggesting a specific mechanism for activating the metal cofactor in the enzyme active site.
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Affiliation(s)
| | - Qi Huang
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, USA
| | - Luke Berry
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, USA
| | - Hayden Kallas
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT, USA
| | - John W Peters
- Institute of Biological Chemistry, The University of Oklahoma, Norman, OK, USA
| | - Lance C Seefeldt
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT, USA
| | - Simone Raugei
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, USA
| | - Brian Bothner
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, USA.
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3
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Truong A, Myerscough D, Campbell I, Atkinson J, Silberg JJ. A cellular selection identifies elongated flavodoxins that support electron transfer to sulfite reductase. Protein Sci 2023; 32:e4746. [PMID: 37551563 PMCID: PMC10503412 DOI: 10.1002/pro.4746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Revised: 07/17/2023] [Accepted: 08/04/2023] [Indexed: 08/09/2023]
Abstract
Flavodoxins (Flds) mediate the flux of electrons between oxidoreductases in diverse metabolic pathways. To investigate whether Flds can support electron transfer to a sulfite reductase (SIR) that evolved to couple with a ferredoxin, we evaluated the ability of Flds to transfer electrons from a ferredoxin-NADP reductase (FNR) to a ferredoxin-dependent SIR using growth complementation of an Escherichia coli strain with a sulfur metabolism defect. We show that Flds from cyanobacteria complement this growth defect when coexpressed with an FNR and an SIR that evolved to couple with a plant ferredoxin. When we evaluated the effect of peptide insertion on Fld-mediated electron transfer, we observed a sensitivity to insertions within regions predicted to be proximal to the cofactor and partner binding sites, while a high insertion tolerance was detected within loops distal from the cofactor and within regions of helices and sheets that are proximal to those loops. Bioinformatic analysis showed that natural Fld sequence variability predicts a large fraction of the motifs that tolerate insertion of the octapeptide SGRPGSLS. These results represent the first evidence that Flds can support electron transfer to assimilatory SIRs, and they suggest that the pattern of insertion tolerance is influenced by interactions with oxidoreductase partners.
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Affiliation(s)
- Albert Truong
- Biochemistry and Cell Biology Graduate Program, Rice University, Houston, Texas, USA
- Department of Biosciences, Rice University, Houston, Texas, USA
| | - Dru Myerscough
- Department of Biosciences, Rice University, Houston, Texas, USA
| | - Ian Campbell
- Department of Biosciences, Rice University, Houston, Texas, USA
| | - Joshua Atkinson
- Department of Biosciences, Rice University, Houston, Texas, USA
| | - Jonathan J Silberg
- Department of Biosciences, Rice University, Houston, Texas, USA
- Department of Bioengineering, Rice University, Houston, Texas, USA
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas, USA
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4
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Alleman AB, Peters JW. Mechanisms for Generating Low Potential Electrons across the Metabolic Diversity of Nitrogen-Fixing Bacteria. Appl Environ Microbiol 2023; 89:e0037823. [PMID: 37154716 PMCID: PMC10231201 DOI: 10.1128/aem.00378-23] [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] [Indexed: 05/10/2023] Open
Abstract
The availability of fixed nitrogen is a limiting factor in the net primary production of all ecosystems. Diazotrophs overcome this limit through the conversion of atmospheric dinitrogen to ammonia. Diazotrophs are phylogenetically diverse bacteria and archaea that exhibit a wide range of lifestyles and metabolisms, including obligate anaerobes and aerobes that generate energy through heterotrophic or autotrophic metabolisms. Despite the diversity of metabolisms, all diazotrophs use the same enzyme, nitrogenase, to reduce N2. Nitrogenase is an O2-sensitive enzyme that requires a high amount of energy in the form of ATP and low potential electrons carried by ferredoxin (Fd) or flavodoxin (Fld). This review summarizes how the diverse metabolisms of diazotrophs utilize different enzymes to generate low potential reducing equivalents for nitrogenase catalysis. These enzymes include substrate-level Fd oxidoreductases, hydrogenases, photosystem I or other light-driven reaction centers, electron bifurcating Fix complexes, proton motive force-driven Rnf complexes, and Fd:NAD(P)H oxidoreductases. Each of these enzymes is critical for generating low potential electrons while simultaneously integrating the native metabolism to balance nitrogenase's overall energy needs. Understanding the diversity of electron transport systems to nitrogenase in various diazotrophs will be essential to guide future engineering strategies aimed at expanding the contributions of biological nitrogen fixation in agriculture.
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Affiliation(s)
- Alexander B. Alleman
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, USA
| | - John W. Peters
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma, USA
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5
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Elliff J, Biswas A, Roshan P, Kuppa S, Patterson A, Mattice J, Chinnaraj M, Burd R, Walker SE, Pozzi N, Antony E, Bothner B, Origanti S. Dynamic states of eIF6 and SDS variants modulate interactions with uL14 of the 60S ribosomal subunit. Nucleic Acids Res 2023; 51:1803-1822. [PMID: 36651285 PMCID: PMC9976893 DOI: 10.1093/nar/gkac1266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 12/20/2022] [Accepted: 12/22/2022] [Indexed: 01/19/2023] Open
Abstract
Assembly of ribosomal subunits into active ribosomal complexes is integral to protein synthesis. Release of eIF6 from the 60S ribosomal subunit primes 60S to associate with the 40S subunit and engage in translation. The dynamics of eIF6 interaction with the uL14 (RPL23) interface of 60S and its perturbation by somatic mutations acquired in Shwachman-Diamond Syndrome (SDS) is yet to be clearly understood. Here, by using a modified strategy to obtain high yields of recombinant human eIF6 we have uncovered the critical interface entailing eight key residues in the C-tail of uL14 that is essential for physical interactions between 60S and eIF6. Disruption of the complementary binding interface by conformational changes in eIF6 disease variants provide a mechanism for weakened interactions of variants with the 60S. Hydrogen-deuterium exchange mass spectrometry (HDX-MS) analyses uncovered dynamic configurational rearrangements in eIF6 induced by binding to uL14 and exposed an allosteric interface regulated by the C-tail of eIF6. Disrupting key residues in the eIF6-60S binding interface markedly limits proliferation of cancer cells, which highlights the significance of therapeutically targeting this interface. Establishing these key interfaces thus provide a therapeutic framework for targeting eIF6 in cancers and SDS.
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Affiliation(s)
- Jonah Elliff
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53233, USA
- Department of Immunology, The University of Iowa, Iowa City, IA 52242, USA
| | - Aparna Biswas
- Department of Biology, Saint Louis University, St. Louis, MO 63103, USA
| | - Poonam Roshan
- Department of Biology, Saint Louis University, St. Louis, MO 63103, USA
| | - Sahiti Kuppa
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, MO 63104, USA
| | - Angela Patterson
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA
| | - Jenna Mattice
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA
| | - Mathivanan Chinnaraj
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, MO 63104, USA
| | - Ryan Burd
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53233, USA
| | - Sarah E Walker
- Department of Biological Sciences, State University of New York, Buffalo, NY 14260, USA
| | - Nicola Pozzi
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, MO 63104, USA
| | - Edwin Antony
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, MO 63104, USA
| | - Brian Bothner
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA
| | - Sofia Origanti
- Department of Biology, Saint Louis University, St. Louis, MO 63103, USA
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6
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Pence N, Lewis N, Alleman AB, Seefeldt LC, Peters JW. Revealing a role for the G subunit in mediating interactions between the nitrogenase component proteins. J Inorg Biochem 2020; 214:111273. [PMID: 33086169 DOI: 10.1016/j.jinorgbio.2020.111273] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 09/16/2020] [Accepted: 10/03/2020] [Indexed: 10/23/2022]
Abstract
Azotobacter vinelandii contains three forms of nitrogenase known as the Mo-, V-, and Fe-nitrogenases. They are all two-component enzyme systems, where the catalytic component, referred to as NifDK, VnfDGK, and AnfDGK, associates with the reductase component, the Fe protein or NifH, VnfH, and AnfH respectively. AnfDGK and VnfDGK have an additional subunit compared to NifDK, termed gamma or AnfG and VnfG, whose role is unknown. The expression of each nitrogenase is tightly regulated by metal availability, however it is known that there is crosstalk between the Mo- and V‑nitrogenases but the Fe‑nitrogenase components cannot support substrate reduction with its Mo‑nitrogenase counterparts. Here, docking models for the nitrogenase complexes were generated in ClusPro 2.0 based on the crystal structure of the Mo‑nitrogenase and refined using the HADDOCK 2.2 refinement interface to identify structural determinants that enable crosstalk between the Mo- and V‑nitrogenase but not the Fe‑nitrogenase. Differing salt bridge interactions were identified at the binding interface of each complex. Specifically, positively charged residues of VnfG enable complementary interactions with NifH and VnfH but not AnfH. Similarly, negatively charged residues of AnfG enable interactions with AnfH but not NifH or VnfH. A role for the G subunit is revealed where VnfG could be mediating crosstalk between the Mo- and V‑nitrogenases while the AnfG subunit on AnfDGK makes interactions with NifH and VnfH unfavorable, reducing competition with NifDK and funneling electrons to the most efficient nitrogenase.
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Affiliation(s)
- Natasha Pence
- Institute of Biological Chemistry, Washington State University, Pullman, WA 99164, United States of America; Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, United States of America
| | - Nathan Lewis
- Institute of Biological Chemistry, Washington State University, Pullman, WA 99164, United States of America
| | - Alexander B Alleman
- Institute of Biological Chemistry, Washington State University, Pullman, WA 99164, United States of America
| | - Lance C Seefeldt
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322, United States of America
| | - John W Peters
- Institute of Biological Chemistry, Washington State University, Pullman, WA 99164, United States of America.
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7
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Abstract
Nitrogenase is the only enzyme capable of reducing N2 to NH3. This challenging reaction requires the coordinated transfer of multiple electrons from the reductase, Fe-protein, to the catalytic component, MoFe-protein, in an ATP-dependent fashion. In the last two decades, there have been significant advances in our understanding of how nitrogenase orchestrates electron transfer (ET) from the Fe-protein to the catalytic site of MoFe-protein and how energy from ATP hydrolysis transduces the ET processes. In this review, we summarize these advances, with focus on the structural and thermodynamic redox properties of nitrogenase component proteins and their complexes, as well as on new insights regarding the mechanism of ET reactions during catalysis and how they are coupled to ATP hydrolysis. We also discuss recently developed chemical, photochemical, and electrochemical methods for uncoupling substrate reduction from ATP hydrolysis, which may provide new avenues for studying the catalytic mechanism of nitrogenase.
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Affiliation(s)
- Hannah L Rutledge
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0340, United States
| | - F Akif Tezcan
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0340, United States
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8
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Abstract
As the only enzyme currently known to reduce dinitrogen (N2) to ammonia (NH3), nitrogenase is of significant interest for bio-inspired catalyst design and for new biotechnologies aiming to produce NH3 from N2. In order to reduce N2, nitrogenase must also hydrolyze at least 16 equivalents of adenosine triphosphate (MgATP), representing the consumption of a significant quantity of energy available to biological systems. Here, we review natural and engineered electron transfer pathways to nitrogenase, including strategies to redirect or redistribute electron flow in vivo towards NH3 production. Further, we also review strategies to artificially reduce nitrogenase in vitro, where MgATP hydrolysis is necessary for turnover, in addition to strategies that are capable of bypassing the requirement of MgATP hydrolysis to achieve MgATP-independent N2 reduction.
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9
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Badalyan A, Yang ZY, Hu B, Luo J, Hu M, Liu TL, Seefeldt LC. An Efficient Viologen-Based Electron Donor to Nitrogenase. Biochemistry 2019; 58:4590-4595. [PMID: 31682410 DOI: 10.1021/acs.biochem.9b00844] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nitrogenase catalyzes the reduction of N2 to NH3, supporting all biological nitrogen fixation. Electron donors to this enzyme are ferredoxin or flavodoxin (in vivo) and sodium dithionite (in vitro). Features of these electron donors put a limit on spectrophotometric studies and electrocatalytic applications of nitrogenase. Although it is common to use methyl viologen as an electron donor for many low-potential oxidoreductases, decreased nitrogenase activity is observed with an increasing concentration of methyl viologen, limiting its utility under many circumstances. In this work, we suggest that this concentration-dependent decrease in activity can be explained by the formation of a dimer of the radical cation of methyl viologen (Me2V•+)2 at higher methyl viologen concentrations. In addition, viologens functionalized with positively and negatively charged groups were synthesized and studied using spectroscopy and cyclic voltammetry. A sulfonated viologen derivative, 1,1'-bis(3-sulfonatopropyl)-4,4'-bipyridinium radical {[(SPr)2V•]-}, was found to support full nitrogenase activity up to a mediator concentration of 3 mM, while the positively charged viologen derivative was not an efficient reductant of nitrogenase due to the high standard redox potential. The utility of [(SPr)2V•]- as an electron donor for nitrogenase was demonstrated by a simple, sensitive spectrophotometric assay for nitrogenase activity that can provide accurate values for the specific activity and turnover rate constant under argon. Under N2, the formation of ammonia was confirmed. Because of the observed full activity of nitrogenase and low overpotential, [(SPr)2V•]- should also prove to be valuable for nitrogenase electrocatalysis, including bioelectrosynthetic N2 reduction.
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Affiliation(s)
- Artavazd Badalyan
- Department of Chemistry and Biochemistry , Utah State University , 0300 Old Main Hill , Logan , Utah 84322 , United States
| | - Zhi-Yong Yang
- Department of Chemistry and Biochemistry , Utah State University , 0300 Old Main Hill , Logan , Utah 84322 , United States
| | - Bo Hu
- Department of Chemistry and Biochemistry , Utah State University , 0300 Old Main Hill , Logan , Utah 84322 , United States
| | - Jian Luo
- Department of Chemistry and Biochemistry , Utah State University , 0300 Old Main Hill , Logan , Utah 84322 , United States
| | - Maowei Hu
- Department of Chemistry and Biochemistry , Utah State University , 0300 Old Main Hill , Logan , Utah 84322 , United States
| | - T Leo Liu
- Department of Chemistry and Biochemistry , Utah State University , 0300 Old Main Hill , Logan , Utah 84322 , United States
| | - Lance C Seefeldt
- Department of Chemistry and Biochemistry , Utah State University , 0300 Old Main Hill , Logan , Utah 84322 , United States
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10
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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]
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11
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Dürichen H, Diekert G, Studenik S. Redox potential changes during ATP-dependent corrinoid reduction determined by redox titrations with europium(II)-DTPA. Protein Sci 2019; 28:1902-1908. [PMID: 31359509 PMCID: PMC6739815 DOI: 10.1002/pro.3699] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 07/17/2019] [Accepted: 07/22/2019] [Indexed: 01/26/2023]
Abstract
Corrinoids are essential cofactors of enzymes involved in the C1 metabolism of anaerobes. The active, super-reduced [CoI ] state of the corrinoid cofactor is highly sensitive to autoxidation. In O-demethylases, the oxidation to inactive [CoII ] is reversed by an ATP-dependent electron transfer catalyzed by the activating enzyme (AE). The redox potential changes of the corrinoid cofactor, which occur during this reaction, were studied by potentiometric titration coupled to UV/visible spectroscopy. By applying europium(II)-diethylenetriaminepentaacetic acid (DTPA) as a reductant, we were able to determine the midpoint potential of the [CoII ]/[CoI ] couple of the protein-bound corrinoid cofactor in the absence and presence of AE and/or ATP. The data revealed that the transfer of electrons from a physiological donor to the corrinoid as the electron-accepting site is achieved by increasing the potential of the corrinoid cofactor from -530 ± 15 mV to -250 ± 10 mV (ESHE , pH 7.5). The first 50 to 100 mV of the shift of the redox potential seem to be caused by the interaction of nucleotide-bound AE with the corrinoid protein or its cofactor. The remaining 150-200 mV had to be overcome by the chemical energy of ATP hydrolysis. The experiments revealed that Eu(II)-DTPA, which was already known as a powerful reducing agent, is a suitable electron donor for titration experiments of low-potential redox centers. Furthermore, the results of this study will contribute to the understanding of thermodynamically unfavorable electron transfer processes driven by the power of ATP hydrolysis.
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Affiliation(s)
- Hendrike Dürichen
- Institute of Microbiology, Department of Applied and Ecological Microbiology, Friedrich Schiller University Jena, Jena, Germany
| | - Gabriele Diekert
- Institute of Microbiology, Department of Applied and Ecological Microbiology, Friedrich Schiller University Jena, Jena, Germany
| | - Sandra Studenik
- Institute of Microbiology, Department of Applied and Ecological Microbiology, Friedrich Schiller University Jena, Jena, Germany
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12
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Badalyan A, Yang ZY, Seefeldt LC. A Voltammetric Study of Nitrogenase Catalysis Using Electron Transfer Mediators. ACS Catal 2019. [DOI: 10.1021/acscatal.8b04290] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Artavazd Badalyan
- Department of Chemistry and Biochemistry, Utah State University, 0300 Old Main Hill, Logan, Utah 84322, United States
| | - Zhi-Yong Yang
- Department of Chemistry and Biochemistry, Utah State University, 0300 Old Main Hill, Logan, Utah 84322, United States
| | - Lance C. Seefeldt
- Department of Chemistry and Biochemistry, Utah State University, 0300 Old Main Hill, Logan, Utah 84322, United States
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13
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Patterson A, Tokmina-Lukaszewska M, Bothner B. Probing Cascade complex composition and stability using native mass spectrometry techniques. Methods Enzymol 2018; 616:87-116. [PMID: 30691656 DOI: 10.1016/bs.mie.2018.10.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Adaptive prokaryotic immune systems rely on clustered regularly interspaced short palindromic repeats and their associated genes to provide the components necessary to clear infection by foreign genetic elements. These immune systems are based on highly specific nucleases that bind DNA or RNA and, upon sequence recognition, degrade the bound nucleic acid. Because of their specificity, CRISPR-Cas systems are being co-opted to edit genes in eukaryotic cells. While the general function of these systems is well understood, an understanding of mechanistic details to facilitate engineering and application to this new arena remains a topic of intense study. Here, we present two methods that have been successfully used to study the structure and mechanism of the Type IE CRISPR system, Cascade, from Escherichia coli. We provide the protocol for a typical native mass spectrometry experiment which, because it allows for analysis of a protein complex without disruption of the noncovalent interactions within the complex, can be used to determine complex composition, architecture, and relative affinity between subunits. We, also, provide the protocol for intact protein hydrogen-deuterium exchange mass spectrometry, which provides insight into the overall conformational stability of the complex and changes in complex stability based on conditions such as substrate binding. Investigating the solution-phase structure, stability, and dynamics of these complexes improves the overall understanding of the mechanism facilitating engineered adjustments to function or utility.
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Affiliation(s)
- Angela Patterson
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, United States
| | | | - Brian Bothner
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, United States.
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14
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Seefeldt LC, Hoffman BM, Peters JW, Raugei S, Beratan DN, Antony E, Dean DR. Energy Transduction in Nitrogenase. Acc Chem Res 2018; 51:2179-2186. [PMID: 30095253 DOI: 10.1021/acs.accounts.8b00112] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Nitrogenase is a complicated two-component enzyme system that uses ATP binding and hydrolysis energy to achieve one of the most difficult chemical reactions in nature, the reduction of N2 to NH3. One component of the Mo-based nitrogenase system, Fe protein, delivers electrons one at a time to the second component, the catalytic MoFe protein. This process occurs through a series of synchronized events collectively called the "Fe protein cycle". Elucidating details of the events associated with this cycle has constituted an important challenge in understanding the nitrogenase mechanism. Electron delivery is a multistep process involving three metal clusters with intra- and interprotein events. It is proposed that the first electron transfer event is a gated intraprotein transfer of one electron from the MoFe protein P-cluster to the FeMo cofactor. Measurement of the effect of osmotic pressure on the rate of this electron transfer process revealed that it is gated by protein conformational changes. This first electron transfer is activated by binding of the Fe protein containing two bound ATP molecules. The mechanism of how this protein-protein association triggers electron transfer remains unknown. The second electron transfer event is proposed to be a rapid interprotein "backfill" with transfer of one electron from the reduced Fe protein 4Fe-4S cluster to the oxidized P-cluster. In this way, electron delivery can be viewed as a case of "deficit spending". Such a deficit-spending electron transfer process can be envisioned as a way to achieve one-direction electron flow, limiting the potential for back electron flow. Hydrolysis of two ATP molecules associated with the Fe protein occurs after the electron transfer and therefore is not used to directly drive the electron transfer. Rather, ATP hydrolysis is proposed to contribute to relaxation of the "activated" conformational state associated with the ATP form of the complex, with the free energy from ATP hydrolysis being used to pay back energy associated with component protein association and electron transfer. Release of inorganic phosphate (Pi) and protein-protein dissociation follow electron transfer and ATP hydrolysis. The rate-limiting step for the Fe protein cycle is not dissociation of the two proteins, as previously believed, but rather is release of Pi after ATP hydrolysis, which is then followed by rapid protein-protein complex dissociation. Nitrogenase is composed of two catalytic halves that do not function independently but rather exhibit anticooperative nuclear motion in which electron transfer in one-half of the complex partially inhibits electron transfer and ATP hydrolysis in the other half. Calculations indicated the existence of anticooperative interactions across the entire nitrogenase complex, suggesting a mechanism for the control of events on opposite ends of this large complex. The mechanistic necessity for this anticooperative process remains unknown. This Account presents a working model for how all of these processes work together in the nitrogenase "machine" to transduce the energy from ATP binding and hydrolysis to drive N2 reduction.
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Affiliation(s)
- Lance C. Seefeldt
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, United States
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Brian M. Hoffman
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - John W. Peters
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
- Institute of Biological Chemistry, Washington State University, Pullman, Washington 99163, United States
| | - Simone Raugei
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
- Institute of Biological Chemistry, Washington State University, Pullman, Washington 99163, United States
| | - David N. Beratan
- Department of Chemistry and Department of Physics, Duke University, Durham, North Carolina 27708, United States
- Department of Biochemistry, Duke University, Durham, North Carolina 27710, United States
| | - Edwin Antony
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin 53201, United States
| | - Dennis R. Dean
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
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Fixen KR, Pal Chowdhury N, Martinez‐Perez M, Poudel S, Boyd ES, Harwood CS. The path of electron transfer to nitrogenase in a phototrophic alpha‐proteobacterium. Environ Microbiol 2018; 20:2500-2508. [DOI: 10.1111/1462-2920.14262] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 04/23/2018] [Accepted: 04/27/2018] [Indexed: 11/28/2022]
Affiliation(s)
| | | | | | - Saroj Poudel
- Department of Microbiology and ImmunologyMontana State UniversityBozeman MT USA
| | - Eric S. Boyd
- Department of Microbiology and ImmunologyMontana State UniversityBozeman MT USA
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Tokmina-Lukaszewska M, Patterson A, Berry L, Scott L, Balasubramanian N, Bothner B. The Role of Mass Spectrometry in Structural Studies of Flavin-Based Electron Bifurcating Enzymes. Front Microbiol 2018; 9:1397. [PMID: 30026733 PMCID: PMC6041385 DOI: 10.3389/fmicb.2018.01397] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2018] [Accepted: 06/07/2018] [Indexed: 12/01/2022] Open
Abstract
For decades, biologists and biochemists have taken advantage of atomic resolution structural models of proteins from X-ray crystallography, nuclear magnetic resonance spectroscopy, and more recently cryo-electron microscopy. However, not all proteins relent to structural analyses using these approaches, and as the depth of knowledge increases, additional data elucidating a mechanistic understanding of protein function is desired. Flavin-based electron bifurcating enzymes, which are responsible for producing high energy compounds through the simultaneous endergonic and exergonic reduction of two intercellular electron carriers (i.e., NAD+ and ferredoxin) are one class of proteins that have challenged structural biologists and in which there is great interest to understand the mechanism behind electron gating. A limited number of X-ray crystallography projects have been successful; however, it is clear that to understand how these enzymes function, techniques that can reveal detailed in solution information about protein structure, dynamics, and interactions involved in the bifurcating reaction are needed. In this review, we cover a general set of mass spectrometry-based techniques that, combined with protein modeling, are capable of providing information on both protein structure and dynamics. Techniques discussed include surface labeling, covalent cross-linking, native mass spectrometry, and hydrogen/deuterium exchange. We cover how biophysical data can be used to validate computationally generated protein models and develop mechanistic explanations for regulation and performance of enzymes and protein complexes. Our focus will be on flavin-based electron bifurcating enzymes, but the broad applicability of the techniques will be showcased.
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Affiliation(s)
| | - Angela Patterson
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, United States
| | - Luke Berry
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, United States
| | - Liam Scott
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, United States
| | | | - Brian Bothner
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, United States
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Yu C, Huang L. Cross-Linking Mass Spectrometry: An Emerging Technology for Interactomics and Structural Biology. Anal Chem 2018; 90:144-165. [PMID: 29160693 PMCID: PMC6022837 DOI: 10.1021/acs.analchem.7b04431] [Citation(s) in RCA: 218] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Clinton Yu
- Department of Physiology & Biophysics, University of California, Irvine, Irvine, CA 92697
| | - Lan Huang
- Department of Physiology & Biophysics, University of California, Irvine, Irvine, CA 92697
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