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Hubáček M, Wey LT, Kourist R, Malihan-Yap L, Nikkanen L, Allahverdiyeva Y. Strong heterologous electron sink outcompetes alternative electron transport pathways in photosynthesis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024. [PMID: 39008444 DOI: 10.1111/tpj.16935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 05/27/2024] [Accepted: 07/03/2024] [Indexed: 07/17/2024]
Abstract
Improvement of photosynthesis requires a thorough understanding of electron partitioning under both natural and strong electron sink conditions. We applied a wide array of state-of-the-art biophysical and biochemical techniques to thoroughly investigate the fate of photosynthetic electrons in the engineered cyanobacterium Synechocystis sp. PCC 6803, a blueprint for photosynthetic biotechnology, expressing the heterologous gene for ene-reductase, YqjM. This recombinant enzyme catalyses the reduction of an exogenously added substrate into the desired product by utilising photosynthetically produced NAD(P)H, enabling whole-cell biotransformation. Through coupling the biotransformation reaction with biophysical measurements, we demonstrated that the strong artificial electron sink, outcompetes the natural electron valves, the flavodiiron protein-driven Mehler-like reaction and cyclic electron transport. These results show that ferredoxin-NAD(P)H-oxidoreductase is the preferred route for delivering photosynthetic electrons from reduced ferredoxin and the cellular NADPH/NADP+ ratio as a key factor in orchestrating photosynthetic electron flux. These insights are crucial for understanding molecular mechanisms of photosynthetic electron transport and harnessing photosynthesis for sustainable bioproduction by engineering the cellular source/sink balance. Furthermore, we conclude that identifying the bioenergetic bottleneck of a heterologous electron sink is a crucial prerequisite for targeted engineering of photosynthetic biotransformation platforms.
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Affiliation(s)
- Michal Hubáček
- Molecular Plant Biology, Department of Life Technologies, University of Turku, Turku, 20014, Finland
| | - Laura T Wey
- Molecular Plant Biology, Department of Life Technologies, University of Turku, Turku, 20014, Finland
| | - Robert Kourist
- Institute of Molecular Biotechnology, NAWI Graz, BioTechMed, Graz University of Technology, Graz, 8010, Austria
| | - Lenny Malihan-Yap
- Institute of Molecular Biotechnology, NAWI Graz, BioTechMed, Graz University of Technology, Graz, 8010, Austria
| | - Lauri Nikkanen
- Molecular Plant Biology, Department of Life Technologies, University of Turku, Turku, 20014, Finland
| | - Yagut Allahverdiyeva
- Molecular Plant Biology, Department of Life Technologies, University of Turku, Turku, 20014, Finland
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2
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Kisgeropoulos E, Bharadwaj VS, Ledinina A, Lubner CE, Mulder DW, Smolinski SL, Boehm M, Gutekunst K, King PW, Svedruzic D. Structural and biophysical properties of a [4Fe4S] ferredoxin-like protein from Synechocystis sp. PCC 6803 with a unique two domain structure. J Inorg Biochem 2024; 251:112428. [PMID: 38008043 DOI: 10.1016/j.jinorgbio.2023.112428] [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: 09/06/2023] [Revised: 10/23/2023] [Accepted: 11/11/2023] [Indexed: 11/28/2023]
Abstract
Electron carrier proteins (ECPs), binding iron-sulfur clusters, are vital components within the intricate network of metabolic and photosynthetic reactions. They play a crucial role in the distribution of reducing equivalents. In Synechocystis sp. PCC 6803, the ECP network includes at least nine ferredoxins. Previous research, including global expression analyses and protein binding studies, has offered initial insights into the functional roles of individual ferredoxins within this network. This study primarily focuses on Ferredoxin 9 (slr2059). Through sequence analysis and computational modeling, Ferredoxin 9 emerges as a unique ECP with a distinctive two-domain architecture. It consists of a C-terminal iron‑sulfur binding domain and an N-terminal domain with homology to Nil-domain proteins, connected by a structurally rigid 4-amino acid linker. Notably, in contrast to canonical [2Fe2S] ferredoxins exemplified by PetF (ssl0020), which feature highly acidic surfaces facilitating electron transfer with photosystem I reaction centers, models of Ferredoxin 9 reveal a more neutral to basic protein surface. Using a combination of electron paramagnetic resonance spectroscopy and square-wave voltammetry on heterologously produced Ferredoxin 9, this study demonstrates that the protein coordinates 2×[4Fe4S]2+/1+ redox-active and magnetically interacting clusters, with measured redox potentials of -420 ± 9 mV and - 516 ± 10 mV vs SHE. A more in-depth analysis of Fdx9's unique structure and protein sequence suggests that this type of Nil-2[4Fe4S] multi-domain ferredoxin is well conserved in cyanobacteria, bearing structural similarities to proteins involved in homocysteine synthesis in methanogens.
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Affiliation(s)
- Effie Kisgeropoulos
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Vivek S Bharadwaj
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Anastasia Ledinina
- Department of Molecular and Structural Biochemistry, North Carolina State University, USA
| | - Carolyn E Lubner
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - David W Mulder
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Sharon L Smolinski
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Marko Boehm
- Department of Biology, Botanical Institute, Christian-Albrechts-University, Kiel, Germany; Department of Molecular Plant Physiology, Bioenergetics in Photoautotrophs, University of Kassel, Kassel, Germany
| | - Kirstin Gutekunst
- Department of Biology, Botanical Institute, Christian-Albrechts-University, Kiel, Germany; Department of Molecular Plant Physiology, Bioenergetics in Photoautotrophs, University of Kassel, Kassel, Germany
| | - Paul W King
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Drazenka Svedruzic
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA.
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3
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Roy RR, Ullmann GM. Virtual Model Compound Approach for Calculating Redox Potentials of [Fe 2S 2]-Cys 4 Centers in Proteins - Structure Quality Matters. J Chem Theory Comput 2023; 19:8930-8941. [PMID: 37974307 DOI: 10.1021/acs.jctc.3c00779] [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: 11/19/2023]
Abstract
The midpoint potential of the [Fe2S2]-Cys4-cluster in proteins is known to vary between -200 and -450 mV. This variation is caused by the different electrostatic environment of the cluster in the respective proteins. Continuum electrostatics can quantify the impact of the protein environment on the redox potential. Thus, if the redox potential of a [Fe2S2]-Cys4-cluster model compound in aqueous solution would be known, then redox potentials in various protein complexes could be calculated. However, [Fe2S2]-Cys4-cluster models are not water-soluble, and thus, their redox potential can not be measured in aqueous solution. To overcome this problem, we introduce a method that we call Virtual Model Compound Approach (VMCA) to extrapolate the model redox potential from known redox potentials of proteins. We carefully selected high-resolution structures for our analysis and divide them into a fit set, for fitting the model redox potential, and an independent test set, to check the validity of the model redox potential. However, from our analysis, we realized that the some structures can not be used as downloaded from the PDB but had to be re-refined in order to calculate reliable redox potentials. Because of the re-refinement, we were able to significantly reduce the standard deviation of our derived model redox potential for the [Fe2S2]-Cys4-cluster from 31 mV to 10 mV. As the model redox potential, we obtained -184 mV. This model redox potential can be used to analyze the redox behavior of [Fe2S2]-Cys4-clusters in larger protein complexes.
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Affiliation(s)
- Rajeev Ranjan Roy
- Computational Biochemistry, Universitätsstr. 30, NWI, University of Bayreuth, Bayreuth, 95440, Germany
| | - G Matthias Ullmann
- Computational Biochemistry, Universitätsstr. 30, NWI, University of Bayreuth, Bayreuth, 95440, Germany
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4
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Burnap RL. Cyanobacterial Bioenergetics in Relation to Cellular Growth and Productivity. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2023; 183:25-64. [PMID: 36764956 DOI: 10.1007/10_2022_215] [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: 02/12/2023]
Abstract
Cyanobacteria, the evolutionary originators of oxygenic photosynthesis, have the capability to convert CO2, water, and minerals into biomass using solar energy. This process is driven by intricate bioenergetic mechanisms that consist of interconnected photosynthetic and respiratory electron transport chains coupled. Over the last few decades, advances in physiochemical analysis, molecular genetics, and structural analysis have enabled us to gain a more comprehensive understanding of cyanobacterial bioenergetics. This includes the molecular understanding of the primary energy conversion mechanisms as well as photoprotective and other dissipative mechanisms that prevent photodamage when the rates of photosynthetic output, primarily in the form of ATP and NADPH, exceed the rates that cellular assimilatory processes consume these photosynthetic outputs. Despite this progress, there is still much to learn about the systems integration and the regulatory circuits that control expression levels for optimal cellular abundance and activity of the photosynthetic complexes and the cellular components that convert their products into biomass. With an improved understanding of these regulatory principles and mechanisms, it should be possible to optimally modify cyanobacteria for enhanced biotechnological purposes.
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Affiliation(s)
- Robert L Burnap
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, USA.
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5
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D'Angelo F, Fernández-Fueyo E, Garcia PS, Shomar H, Pelosse M, Manuel RR, Büke F, Liu S, van den Broek N, Duraffourg N, de Ram C, Pabst M, Bouveret E, Gribaldo S, Py B, Ollagnier de Choudens S, Barras F, Bokinsky G. Cellular assays identify barriers impeding iron-sulfur enzyme activity in a non-native prokaryotic host. eLife 2022; 11:70936. [PMID: 35244541 PMCID: PMC8896826 DOI: 10.7554/elife.70936] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 02/03/2022] [Indexed: 11/24/2022] Open
Abstract
Iron-sulfur (Fe-S) clusters are ancient and ubiquitous protein cofactors and play irreplaceable roles in many metabolic and regulatory processes. Fe-S clusters are built and distributed to Fe-S enzymes by dedicated protein networks. The core components of these networks are widely conserved and highly versatile. However, Fe-S proteins and enzymes are often inactive outside their native host species. We sought to systematically investigate the compatibility of Fe-S networks with non-native Fe-S enzymes. By using collections of Fe-S enzyme orthologs representative of the entire range of prokaryotic diversity, we uncovered a striking correlation between phylogenetic distance and probability of functional expression. Moreover, coexpression of a heterologous Fe-S biogenesis pathway increases the phylogenetic range of orthologs that can be supported by the foreign host. We also find that Fe-S enzymes that require specific electron carrier proteins are rarely functionally expressed unless their taxon-specific reducing partners are identified and co-expressed. We demonstrate how these principles can be applied to improve the activity of a radical S-adenosyl methionine(rSAM) enzyme from a Streptomyces antibiotic biosynthesis pathway in Escherichia coli. Our results clarify how oxygen sensitivity and incompatibilities with foreign Fe-S and electron transfer networks each impede heterologous activity. In particular, identifying compatible electron transfer proteins and heterologous Fe-S biogenesis pathways may prove essential for engineering functional Fe-S enzyme-dependent pathways.
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Affiliation(s)
- Francesca D'Angelo
- Unit Stress Adaptation and Metabolism of Enterobacteria, Department of Microbiology, Université de Paris, UMR CNRS 2001, Institut Pasteur, Paris, France
| | - Elena Fernández-Fueyo
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, Netherlands
| | - Pierre Simon Garcia
- Unit Stress Adaptation and Metabolism of Enterobacteria, Department of Microbiology, Université de Paris, UMR CNRS 2001, Institut Pasteur, Paris, France.,Institut Pasteur, Université de Paris, CNRS UMR6047, Evolutionary Biology of the Microbial Cell, Department of Microbiology, Paris, France
| | - Helena Shomar
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, Netherlands
| | - Martin Pelosse
- Univ. Grenoble Alpes, CNRS, CEA, IRIG, Laboratoire de Chimie et Biologie des Métaux, Grenoble, France
| | - Rita Rebelo Manuel
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, Netherlands
| | - Ferhat Büke
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, Netherlands
| | - Siyi Liu
- Aix-Marseille Université-CNRS, Laboratoire de Chimie Bactérienne UMR 7283, Institut de Microbiologie de la Méditerranée, Institut Microbiologie Bioénergies Biotechnologie, Marseille, France
| | - Niels van den Broek
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, Netherlands
| | - Nicolas Duraffourg
- Univ. Grenoble Alpes, CNRS, CEA, IRIG, Laboratoire de Chimie et Biologie des Métaux, Grenoble, France
| | - Carol de Ram
- Department of Biotechnology, Delft University of Technology, Delft, Netherlands
| | - Martin Pabst
- Department of Biotechnology, Delft University of Technology, Delft, Netherlands
| | - Emmanuelle Bouveret
- Unit Stress Adaptation and Metabolism of Enterobacteria, Department of Microbiology, Université de Paris, UMR CNRS 2001, Institut Pasteur, Paris, France
| | - Simonetta Gribaldo
- Institut Pasteur, Université de Paris, CNRS UMR6047, Evolutionary Biology of the Microbial Cell, Department of Microbiology, Paris, France
| | - Béatrice Py
- Aix-Marseille Université-CNRS, Laboratoire de Chimie Bactérienne UMR 7283, Institut de Microbiologie de la Méditerranée, Institut Microbiologie Bioénergies Biotechnologie, Marseille, France
| | | | - Frédéric Barras
- Unit Stress Adaptation and Metabolism of Enterobacteria, Department of Microbiology, Université de Paris, UMR CNRS 2001, Institut Pasteur, Paris, France
| | - Gregory Bokinsky
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, Netherlands
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6
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Wang Y, Chen X, Spengler K, Terberger K, Boehm M, Appel J, Barske T, Timm S, Battchikova N, Hagemann M, Gutekunst K. Pyruvate:ferredoxin oxidoreductase and low abundant ferredoxins support aerobic photomixotrophic growth in cyanobacteria. eLife 2022; 11:71339. [PMID: 35138247 PMCID: PMC8887894 DOI: 10.7554/elife.71339] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 02/06/2022] [Indexed: 11/24/2022] Open
Abstract
The decarboxylation of pyruvate is a central reaction in the carbon metabolism of all organisms. It is catalyzed by the pyruvate:ferredoxin oxidoreductase (PFOR) and the pyruvate dehydrogenase (PDH) complex. Whereas PFOR reduces ferredoxin, the PDH complex utilizes NAD+. Anaerobes rely on PFOR, which was replaced during evolution by the PDH complex found in aerobes. Cyanobacteria possess both enzyme systems. Our data challenge the view that PFOR is exclusively utilized for fermentation. Instead, we show, that the cyanobacterial PFOR is stable in the presence of oxygen in vitro and is required for optimal photomixotrophic growth under aerobic and highly reducing conditions while the PDH complex is inactivated. We found that cells rely on a general shift from utilizing NAD(H)- to ferredoxin-dependent enzymes under these conditions. The utilization of ferredoxins instead of NAD(H) saves a greater share of the Gibbs-free energy, instead of wasting it as heat. This obviously simultaneously decelerates metabolic reactions as they operate closer to their thermodynamic equilibrium. It is common thought that during evolution, ferredoxins were replaced by NAD(P)H due to their higher stability in an oxidizing atmosphere. However, the utilization of NAD(P)H could also have been favored due to a higher competitiveness because of an accelerated metabolism.
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Affiliation(s)
- Yingying Wang
- Department of Biology, Christian-Albrechts University, Kiel, Germany
| | - Xi Chen
- Department of Biology, Christian-Albrechts University, Kiel, Germany
| | | | | | - Marko Boehm
- Department of Molecular Plant Physiology, University of Kassel, Kassel, Germany
| | - Jens Appel
- Department of Molecular Plant Physiology, University of Kassel, Kassel, Germany
| | - Thomas Barske
- Plant Physiology Department, University of Rostock, Rostock, Germany
| | - Stefan Timm
- Plant Physiology Department, University of Rostock, Rostock, Germany
| | | | - Martin Hagemann
- Plant Physiology Department, University of Rostock, Rostock, Germany
| | - Kirstin Gutekunst
- Department of Molecular Plant Physiology, University of Kassel, Kassel, Germany
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7
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Wise CE, Ledinina AE, Yuly JL, Artz JH, Lubner CE. The role of thermodynamic features on the functional activity of electron bifurcating enzymes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2021; 1862:148377. [PMID: 33453185 DOI: 10.1016/j.bbabio.2021.148377] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 01/05/2021] [Accepted: 01/06/2021] [Indexed: 11/25/2022]
Abstract
Electron bifurcation is a biological mechanism to drive a thermodynamically unfavorable redox reaction through direct coupling with an exergonic reaction. This process allows microorganisms to generate high energy reducing equivalents in order to sustain life and is often found in anaerobic metabolism, where the energy economy of the cell is poor. Recent work has revealed details of the redox energy landscapes for a variety of electron bifurcating enzymes, greatly expanding the understanding of how energy is transformed by this unique mechanism. Here we highlight the plasticity of these emerging landscapes, what is known regarding their mechanistic underpinnings, and provide a context for interpreting their biochemical activity within the physiological framework. We conclude with an outlook for propelling the field toward an integrative understanding of the impact of electron bifurcation.
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Affiliation(s)
| | | | | | - Jacob H Artz
- National Renewable Energy Laboratory, Golden, CO, USA
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8
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Melin F, Hellwig P. Redox Properties of the Membrane Proteins from the Respiratory Chain. Chem Rev 2020; 120:10244-10297. [DOI: 10.1021/acs.chemrev.0c00249] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Frederic Melin
- Chimie de la Matière Complexe UMR 7140, Laboratoire de Bioelectrochimie et Spectroscopie, CNRS-Université de Strasbourg, 1 rue Blaise Pascal, 67070 Strasbourg, France
| | - Petra Hellwig
- Chimie de la Matière Complexe UMR 7140, Laboratoire de Bioelectrochimie et Spectroscopie, CNRS-Université de Strasbourg, 1 rue Blaise Pascal, 67070 Strasbourg, France
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9
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Zuccarello L, Berthomieu C, Boussac A, Brubach JB, Díaz-Moreno I, Díaz Quintana AJ, Hienerwadel R. Protonation of the Cysteine Axial Ligand Investigated in His/Cys c-Type Cytochrome by UV-Vis and Mid- and Far-IR Spectroscopy. J Phys Chem Lett 2020; 11:4198-4205. [PMID: 32364390 DOI: 10.1021/acs.jpclett.0c01016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
His/Cys coordination was recently found in several c-type cytochromes, which could act as sensors, in electron transport or in regulation. Toward a better understanding of Cys function and reactivity in these cytochromes, we compare cytochrome c6 (c6wt) from the cyanobacterium Nostoc PCC 7120 with its Met58Cys mutant. We probe the axial ligands and heme properties by combining visible and mid- to far-FTIR difference spectroscopies. Cys58 determines the strong negative redox potential and pH dependence of M58C (EmM58C = -375 mV, versus Emc6wt = +339 mV). Mid-IR (notably Cys ν(SH), His ν(C5N1), heme δ(CmH)) and far-IR (ν(Fe(II)-His), ν(His-Fe(III)-Cys)) markers of the heme and ligands show that Cys58 remains a strong thiolate ligand of reduced Met58Cys at alkaline pH, while it is protonated at pH 7.5, is stabilized by a strong hydrogen bonding interaction, and weakly interacts with Fe(II). These data provide a benchmark for further analysis of c-type cytochromes with natural His/Cys coordination.
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Affiliation(s)
- Lidia Zuccarello
- CEA, CNRS, Aix Marseille Univ., BIAM, Interactions Protéine Métal UMR 7265, 13108 Saint Paul-Lez-Durance, France
- Aix Marseille Univ., CEA, CNRS, BIAM, Luminy Genetics and Biophysic of Plants, UMR 7265, 13288 Marseille Cedex, France
| | - Catherine Berthomieu
- CEA, CNRS, Aix Marseille Univ., BIAM, Interactions Protéine Métal UMR 7265, 13108 Saint Paul-Lez-Durance, France
| | - Alain Boussac
- I2BC, UMR CNRS 9198, CEA Saclay, 91191 Gif-sur-Yvette, France
| | - Jean-Blaise Brubach
- Synchrotron SOLEIL, AILES Beamline, L'Orme des Merisier, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex, France
| | - Irene Díaz-Moreno
- Instituto de Investigaciones Químicas (IIQ), Centro de Investigaciones Científicas Isla de la Cartuja (cicCartuja), Universidad de Sevilla - Consejo Superior de Investigaciones Científicas (CSIC), Avda. Américo Vespucio 49, Sevilla 41092, Spain
| | - Antonio J Díaz Quintana
- Instituto de Investigaciones Químicas (IIQ), Centro de Investigaciones Científicas Isla de la Cartuja (cicCartuja), Universidad de Sevilla - Consejo Superior de Investigaciones Científicas (CSIC), Avda. Américo Vespucio 49, Sevilla 41092, Spain
| | - Rainer Hienerwadel
- Aix Marseille Univ., CEA, CNRS, BIAM, Luminy Genetics and Biophysic of Plants, UMR 7265, 13288 Marseille Cedex, France
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10
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Campbell IJ, Olmos JL, Xu W, Kahanda D, Atkinson JT, Sparks ON, Miller MD, Phillips GN, Bennett GN, Silberg JJ. Prochlorococcus phage ferredoxin: structural characterization and electron transfer to cyanobacterial sulfite reductases. J Biol Chem 2020; 295:10610-10623. [PMID: 32434930 DOI: 10.1074/jbc.ra120.013501] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 05/15/2020] [Indexed: 01/13/2023] Open
Abstract
Marine cyanobacteria are infected by phages whose genomes encode ferredoxin (Fd) electron carriers. These Fds are thought to redirect the energy harvested from light to phage-encoded oxidoreductases that enhance viral fitness, but it is unclear how the biophysical properties and partner specificities of phage Fds relate to those of photosynthetic organisms. Here, results of a bioinformatics analysis using a sequence similarity network revealed that phage Fds are most closely related to cyanobacterial Fds that transfer electrons from photosystems to oxidoreductases involved in nutrient assimilation. Structural analysis of myovirus P-SSM2 Fd (pssm2-Fd), which infects the cyanobacterium Prochlorococcus marinus, revealed high levels of similarity to cyanobacterial Fds (root mean square deviations of ≤0.5 Å). Additionally, pssm2-Fd exhibited a low midpoint reduction potential (-336 mV versus a standard hydrogen electrode), similar to other photosynthetic Fds, although it had lower thermostability (Tm = 28 °C) than did many other Fds. When expressed in an Escherichia coli strain deficient in sulfite assimilation, pssm2-Fd complemented bacterial growth when coexpressed with a P. marinus sulfite reductase, revealing that pssm2-Fd can transfer electrons to a host protein involved in nutrient assimilation. The high levels of structural similarity with cyanobacterial Fds and reactivity with a host sulfite reductase suggest that phage Fds evolved to transfer electrons to cyanobacterially encoded oxidoreductases.
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Affiliation(s)
- Ian J Campbell
- Biochemistry and Cell Biology Graduate Program, Rice University, Houston, Texas, USA.,Department of Biosciences, Rice University, Houston, Texas, USA
| | - Jose Luis Olmos
- Biochemistry and Cell Biology Graduate Program, Rice University, Houston, Texas, USA.,Department of Biosciences, Rice University, Houston, Texas, USA
| | - Weijun Xu
- Department of Biosciences, Rice University, Houston, Texas, USA
| | | | | | | | | | - George N Phillips
- Department of Biosciences, Rice University, Houston, Texas, USA.,Department of Chemistry, Rice University, Houston, Texas, USA
| | - George N Bennett
- Department of Biosciences, Rice University, Houston, Texas, USA.,Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas, USA
| | - Jonathan J Silberg
- Department of Biosciences, Rice University, Houston, Texas, USA .,Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas, USA.,Department of Bioengineering, Rice University, Houston, Texas, USA
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11
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Artz JH, Tokmina-Lukaszewska M, Mulder DW, Lubner CE, Gutekunst K, Appel J, Bothner B, Boehm M, King PW. The structure and reactivity of the HoxEFU complex from the cyanobacterium Synechocystis sp. PCC 6803. J Biol Chem 2020; 295:9445-9454. [PMID: 32409585 PMCID: PMC7363133 DOI: 10.1074/jbc.ra120.013136] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 05/11/2020] [Indexed: 11/19/2022] Open
Abstract
Cyanobacterial Hox is a [NiFe] hydrogenase that consists of the hydrogen (H2)-activating subunits HoxYH, which form a complex with the HoxEFU assembly to mediate reactions with soluble electron carriers like NAD(P)H and ferredoxin (Fdx), thereby coupling photosynthetic electron transfer to energy-transforming catalytic reactions. Researchers studying the HoxEFUYH complex have observed that HoxEFU can be isolated independently of HoxYH, leading to the hypothesis that HoxEFU is a distinct functional subcomplex rather than an artifact of Hox complex isolation. Moreover, outstanding questions about the reactivity of Hox with natural substrates and the site(s) of substrate interactions and coupling of H2, NAD(P)H, and Fdx remain to be resolved. To address these questions, here we analyzed recombinantly produced HoxEFU by electron paramagnetic resonance spectroscopy and kinetic assays with natural substrates. The purified HoxEFU subcomplex catalyzed electron transfer reactions among NAD(P)H, flavodoxin, and several ferredoxins, thus functioning in vitro as a shuttle among different cyanobacterial pools of reducing equivalents. Both Fdx1-dependent reductions of NAD+ and NADP+ were cooperative. HoxEFU also catalyzed the flavodoxin-dependent reduction of NAD(P)+, Fdx2-dependent oxidation of NADH and Fdx4- and Fdx11-dependent reduction of NAD+. MS-based mapping identified an Fdx1-binding site at the junction of HoxE and HoxF, adjacent to iron-sulfur (FeS) clusters in both subunits. Overall, the reactivity of HoxEFU observed here suggests that it functions in managing peripheral electron flow from photosynthetic electron transfer, findings that reveal detailed insights into how ubiquitous cellular components may be used to allocate energy flow into specific bioenergetic products.
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Affiliation(s)
- Jacob H Artz
- Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado, USA
| | | | - David W Mulder
- Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado, USA
| | - Carolyn E Lubner
- Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado, USA
| | | | - Jens Appel
- Botanical Institute, Christian-Albrechts-University, Kiel, Germany
| | - Brian Bothner
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA
| | - Marko Boehm
- Botanical Institute, Christian-Albrechts-University, Kiel, Germany
| | - Paul W King
- Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado, USA
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