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Molinas M, Meibom KL, Faizova R, Mazzanti M, Bernier-Latmani R. Mechanism of Reduction of Aqueous U(V)-dpaea and Solid-Phase U(VI)-dpaea Complexes: The Role of Multiheme c-Type Cytochromes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:7537-7546. [PMID: 37133831 DOI: 10.1021/acs.est.3c00666] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The biological reduction of soluble U(VI) complexes to form immobile U(IV) species has been proposed to remediate contaminated sites. It is well established that multiheme c-type cytochromes (MHCs) are key mediators of electron transfer to aqueous phase U(VI) complexes for bacteria such as Shewanella oneidensis MR-1. Recent studies have confirmed that the reduction proceeds via a first electron transfer forming pentavalent U(V) species that readily disproportionate. However, in the presence of the stabilizing aminocarboxylate ligand, dpaea2- (dpaeaH2═bis(pyridyl-6-methyl-2-carboxylate)-ethylamine), biologically produced U(V) persisted in aqueous solution at pH 7. We aim to pinpoint the role of MHC in the reduction of U(V)-dpaea and to establish the mechanism of solid-phase U(VI)-dpaea reduction. To that end, we investigated U-dpaea reduction by two deletion mutants of S. oneidensis MR-1-one lacking outer membrane MHCs and the other lacking all outer membrane MHCs and a transmembrane MHC-and by the purified outer membrane MHC, MtrC. Our results suggest that solid-phase U(VI)-dpaea is reduced primarily by outer membrane MHCs. Additionally, MtrC can directly transfer electrons to U(V)-dpaea to form U(IV) species but is not strictly necessary, underscoring the primary involvement of outer membrane MHCs in the reduction of this pentavalent U species but not excluding that of periplasmic MHCs.
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Affiliation(s)
- Margaux Molinas
- Environmental Microbiology Laboratory, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland
| | - Karin Lederballe Meibom
- Environmental Microbiology Laboratory, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland
| | - Radmila Faizova
- Group of Coordination Chemistry, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland
| | - Marinella Mazzanti
- Group of Coordination Chemistry, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland
| | - Rizlan Bernier-Latmani
- Environmental Microbiology Laboratory, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland
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Piper SEH, Casadevall C, Reisner E, Clarke TA, Jeuken LJC, Gates AJ, Butt JN. Photocatalytic Removal of the Greenhouse Gas Nitrous Oxide by Liposomal Microreactors. Angew Chem Int Ed Engl 2022; 61:e202210572. [PMID: 35951464 PMCID: PMC9825952 DOI: 10.1002/anie.202210572] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Indexed: 01/11/2023]
Abstract
Nitrous oxide (N2 O) is a potent greenhouse and ozone-reactive gas for which emissions are growing rapidly due to increasingly intensive agriculture. Synthetic catalysts for N2 O decomposition typically contain precious metals and/or operate at elevated temperatures driving a desire for more sustainable alternatives. Here we demonstrate self-assembly of liposomal microreactors enabling catalytic reduction of N2 O to the climate neutral product N2 . Photoexcitation of graphitic N-doped carbon dots delivers electrons to encapsulated N2 O Reductase enzymes via a lipid-soluble biomolecular wire provided by the MtrCAB protein complex. Within the microreactor, electron transfer from MtrCAB to N2 O Reductase is facilitated by the general redox mediator methyl viologen. The liposomal microreactors use only earth-abundant elements to catalyze N2 O removal in ambient, aqueous conditions.
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Affiliation(s)
- Samuel E. H. Piper
- School of ChemistryUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUK
| | - Carla Casadevall
- Yusuf Hamied Department of ChemistryUniversity of CambridgeLensfield RoadCambridgeCB2 1EWUK
| | - Erwin Reisner
- Yusuf Hamied Department of ChemistryUniversity of CambridgeLensfield RoadCambridgeCB2 1EWUK
| | - Thomas A. Clarke
- School of Biological SciencesUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUK
| | - Lars J. C. Jeuken
- Leiden Institute of ChemistryLeiden UniversityPO Box 95022300 RALeidenThe Netherlands
| | - Andrew J. Gates
- School of Biological SciencesUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUK
| | - Julea N. Butt
- School of ChemistryUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUK,School of Biological SciencesUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUK
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Piper SEH, Casadevall C, Reisner E, Clarke TA, Jeuken LJC, Gates AJ, Butt JN. Photocatalytic Removal of the Greenhouse Gas Nitrous Oxide by Liposomal Microreactors. ANGEWANDTE CHEMIE (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 134:e202210572. [PMID: 38529325 PMCID: PMC10962689 DOI: 10.1002/ange.202210572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Indexed: 11/11/2022]
Abstract
Nitrous oxide (N2O) is a potent greenhouse and ozone-reactive gas for which emissions are growing rapidly due to increasingly intensive agriculture. Synthetic catalysts for N2O decomposition typically contain precious metals and/or operate at elevated temperatures driving a desire for more sustainable alternatives. Here we demonstrate self-assembly of liposomal microreactors enabling catalytic reduction of N2O to the climate neutral product N2. Photoexcitation of graphitic N-doped carbon dots delivers electrons to encapsulated N2O Reductase enzymes via a lipid-soluble biomolecular wire provided by the MtrCAB protein complex. Within the microreactor, electron transfer from MtrCAB to N2O Reductase is facilitated by the general redox mediator methyl viologen. The liposomal microreactors use only earth-abundant elements to catalyze N2O removal in ambient, aqueous conditions.
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Affiliation(s)
- Samuel E. H. Piper
- School of ChemistryUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUK
| | - Carla Casadevall
- Yusuf Hamied Department of ChemistryUniversity of CambridgeLensfield RoadCambridgeCB2 1EWUK
| | - Erwin Reisner
- Yusuf Hamied Department of ChemistryUniversity of CambridgeLensfield RoadCambridgeCB2 1EWUK
| | - Thomas A. Clarke
- School of Biological SciencesUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUK
| | - Lars J. C. Jeuken
- Leiden Institute of ChemistryLeiden UniversityPO Box 95022300 RALeidenThe Netherlands
| | - Andrew J. Gates
- School of Biological SciencesUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUK
| | - Julea N. Butt
- School of ChemistryUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUK
- School of Biological SciencesUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUK
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4
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Kruyer NS, Sugianto W, Tickman BI, Alba Burbano D, Noireaux V, Carothers JM, Peralta-Yahya P. Membrane Augmented Cell-Free Systems: A New Frontier in Biotechnology. ACS Synth Biol 2021; 10:670-681. [PMID: 33749249 DOI: 10.1021/acssynbio.0c00625] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Membrane proteins are present in a wide array of cellular processes from primary and secondary metabolite synthesis to electron transport and single carbon metabolism. A key barrier to applying membrane proteins industrially is their difficult functional production. Beyond expression, folding, and membrane insertion, membrane protein activity is influenced by the physicochemical properties of the associated membrane, making it difficult to achieve optimal membrane protein performance outside the endogenous host. In this review, we highlight recent work on production of membrane proteins in membrane augmented cell-free systems (CFSs) and applications thereof. CFSs lack membranes and can thus be augmented with user-specified, tunable, mimetic membranes to generate customized environments for production of functional membrane proteins of interest. Membrane augmented CFSs would enable the synthesis of more complex plant secondary metabolites, the growth and division of synthetic cells for drug delivery and cell therapeutic applications, as well as enable green energy applications including methane capture and artificial photosynthesis.
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Affiliation(s)
- Nicholas S. Kruyer
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Widianti Sugianto
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Benjamin I. Tickman
- Molecular Engineering & Sciences Institute and Center for Synthetic Biology, University of Washington, Seattle, Washington 98195, United States
| | - Diego Alba Burbano
- Molecular Engineering & Sciences Institute and Center for Synthetic Biology, University of Washington, Seattle, Washington 98195, United States
- Department of Chemical Engineering, University of Washington, Seattle, Washington 98195, United States
| | - Vincent Noireaux
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - James M. Carothers
- Molecular Engineering & Sciences Institute and Center for Synthetic Biology, University of Washington, Seattle, Washington 98195, United States
- Department of Chemical Engineering, University of Washington, Seattle, Washington 98195, United States
| | - Pamela Peralta-Yahya
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
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5
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LUO X, WU Y, LIU T, LI F, LI X, CHEN D, WANG Y. Quantifying Redox Dynamics of c-Type Cytochromes in a Living Cell Suspension of Dissimilatory Metal-reducing Bacteria. ANAL SCI 2019; 35:315-321. [DOI: 10.2116/analsci.18p394] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Xiaobo LUO
- Guangzhou Institute of Geochemistry, Chinese Academy of Sciences
- Guangdong Institute of Eco-environmental Science & Technology, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management
- University of Chinese Academy of Sciences
| | - Yundang WU
- Guangdong Institute of Eco-environmental Science & Technology, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management
| | - Tongxu LIU
- Guangdong Institute of Eco-environmental Science & Technology, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management
| | - Fangbai LI
- Guangdong Institute of Eco-environmental Science & Technology, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management
| | - Xiaomin LI
- The Environmental Research Institute, MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University
| | - Dandan CHEN
- Guangdong Institute of Eco-environmental Science & Technology, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management
| | - Ying WANG
- Guangdong Institute of Eco-environmental Science & Technology, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management
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Metal Reduction and Protein Secretion Genes Required for Iodate Reduction by Shewanella oneidensis. Appl Environ Microbiol 2019; 85:AEM.02115-18. [PMID: 30446562 DOI: 10.1128/aem.02115-18] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 11/07/2018] [Indexed: 01/28/2023] Open
Abstract
The metal-reducing gammaproteobacterium Shewanella oneidensis reduces iodate (IO3 -) as an anaerobic terminal electron acceptor. Microbial IO3 - electron transport pathways are postulated to terminate with nitrate (NO3 -) reductase, which reduces IO3 - as an alternative electron acceptor. Recent studies with S. oneidensis, however, have demonstrated that NO3 - reductase is not involved in IO3 - reduction. The main objective of the present study was to determine the metal reduction and protein secretion genes required for IO3 - reduction by Shewanella oneidensis with lactate, formate, or H2 as the electron donor. With all electron donors, the type I and type V protein secretion mutants retained wild-type IO3 - reduction activity, while the type II protein secretion mutant lacking the outer membrane secretin GspD was impaired in IO3 - reduction. Deletion mutants lacking the cyclic AMP receptor protein (CRP), cytochrome maturation permease CcmB, and inner membrane-tethered c-type cytochrome CymA were impaired in IO3 - reduction with all electron donors, while deletion mutants lacking c-type cytochrome MtrA and outer membrane β-barrel protein MtrB of the outer membrane MtrAB module were impaired in IO3 - reduction with only lactate as an electron donor. With all electron donors, mutants lacking the c-type cytochromes OmcA and MtrC of the metal-reducing extracellular electron conduit MtrCAB retained wild-type IO3 - reduction activity. These findings indicate that IO3 - reduction by S. oneidensis involves electron donor-dependent metal reduction and protein secretion pathway components, including the outer membrane MtrAB module and type II protein secretion of an unidentified IO3 - reductase to the S. oneidensis outer membrane.IMPORTANCE Microbial iodate (IO3 -) reduction is a major component in the biogeochemical cycling of iodine and the bioremediation of iodine-contaminated environments; however, the molecular mechanism of microbial IO3 - reduction is poorly understood. Results of the present study indicate that outer membrane (type II) protein secretion and metal reduction genes encoding the outer membrane MtrAB module of the extracellular electron conduit MtrCAB are required for IO3 - reduction by S. oneidensis On the other hand, the metal-reducing c-type cytochrome MtrC of the extracellular electron conduit is not required for IO3 - reduction by S. oneidensis These findings indicate that the IO3 - electron transport pathway terminates with an as yet unidentified IO3 - reductase that associates with the outer membrane MtrAB module to deliver electrons extracellularly to IO3.
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Duarte AG, Catarino T, White GF, Lousa D, Neukirchen S, Soares CM, Sousa FL, Clarke TA, Pereira IAC. An electrogenic redox loop in sulfate reduction reveals a likely widespread mechanism of energy conservation. Nat Commun 2018; 9:5448. [PMID: 30575735 PMCID: PMC6303296 DOI: 10.1038/s41467-018-07839-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 11/27/2018] [Indexed: 02/02/2023] Open
Abstract
The bioenergetics of anaerobic metabolism frequently relies on redox loops performed by membrane complexes with substrate- and quinone-binding sites on opposite sides of the membrane. However, in sulfate respiration (a key process in the biogeochemical sulfur cycle), the substrate- and quinone-binding sites of the QrcABCD complex are periplasmic, and their role in energy conservation has not been elucidated. Here we show that the QrcABCD complex of Desulfovibrio vulgaris is electrogenic, as protons and electrons required for quinone reduction are extracted from opposite sides of the membrane, with a H+/e− ratio of 1. Although the complex does not act as a H+-pump, QrcD may include a conserved proton channel leading from the N-side to the P-side menaquinone pocket. Our work provides evidence of how energy is conserved during dissimilatory sulfate reduction, and suggests mechanisms behind the functions of related bacterial respiratory complexes in other bioenergetic contexts. The bacterial complex QrcABCD plays a key role in the bioenergetics of sulfate respiration. Here, Duarte et al. show that this complex is electrogenic, with protons and electrons required for quinone reduction being extracted from opposite sides of the membrane.
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Affiliation(s)
- Américo G Duarte
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal
| | - Teresa Catarino
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal.,Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516, Caparica, Portugal
| | - Gaye F White
- Centre for Molecular and Structural Biochemistry, School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK
| | - Diana Lousa
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal
| | - Sinje Neukirchen
- Division of Archaea Biology and Ecogenomics, Department of Ecogenomics and Systems Biology, University of Vienna, Althanstrasse 14 UZA I, 1090, Vienna, Austria
| | - Cláudio M Soares
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal
| | - Filipa L Sousa
- Division of Archaea Biology and Ecogenomics, Department of Ecogenomics and Systems Biology, University of Vienna, Althanstrasse 14 UZA I, 1090, Vienna, Austria
| | - Thomas A Clarke
- Centre for Molecular and Structural Biochemistry, School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK
| | - Inês A C Pereira
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal.
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Zhong Y, Shi L. Genomic Analyses of the Quinol Oxidases and/or Quinone Reductases Involved in Bacterial Extracellular Electron Transfer. Front Microbiol 2018; 9:3029. [PMID: 30619124 PMCID: PMC6295460 DOI: 10.3389/fmicb.2018.03029] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 11/23/2018] [Indexed: 11/18/2022] Open
Abstract
To exchange electrons with extracellular substrates, some microorganisms employ extracellular electron transfer (EET) pathways that physically connect extracellular redox reactions to intracellular metabolic activity. These pathways are made of redox and structural proteins that work cooperatively to transfer electrons between extracellular substrates and the cytoplasmic membrane. Crucial to the bacterial and archaeal EET pathways are the quinol oxidases and/or quinone reductases in the cytoplasmic membrane where they recycle the quinone/quinol pool in the cytoplasmic membrane during EET reaction. Up to date, three different families of quinol oxidases and/or quinone reductases involved in bacterial EET have been discovered. They are the CymA, CbcL/MtrH/MtoC, and ImcH families of quinol oxidases and/or quinone reductases that are all multiheme c-type cytochromes (c-Cyts). To investigate to what extent they are distributed among microorganisms, we search the bacterial as well as archaeal genomes for the homologs of these c-Cyts. Search results reveal that the homologs of these c-Cyts are only found in the Domain Bacteria. Moreover, the CymA homologs are only found in the phylum of Proteobacteria and most of them are in the Shewanella genus. In addition to Shewanella sp., CymA homologs are also found in other Fe(III)-reducing bacteria, such as of Vibrio parahaemolyticus. In contrast to CymA, CbcL/MtrH/MtoC, and ImcH homologs are much more widespread. CbcL/MtrH/MtoC homologs are found in 15 phyla, while ImcH homologs are found in 12 phyla. Furthermore, the heme-binding motifs of CbcL/MtrH/MtoC and ImcH homologs vary greatly, ranging from 3 to 23 and 6 to 10 heme-binding motifs for CbcL/MtrH/MtoC and ImcH homologs, respectively. Moreover, CymA and CbcL/MtrH/MtoC homologs are found in both Fe(III)-reducing and Fe(II)-oxidizing bacteria, suggesting that these families of c-Cyts catalyze both quinol-oxidizing and quinone-reducing reactions. ImcH homologs are only found in the Fe(III)-reducing bacteria, implying that they are only the quinol oxidases. Finally, some bacteria have the homologs of two different families of c-Cyts, which may improve the bacterial capability to exchange electrons with extracellular substrates.
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Affiliation(s)
- Yuhong Zhong
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, China
| | - Liang Shi
- Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, China.,State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, China
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Edwards MJ, White GF, Lockwood CW, Lawes MC, Martel A, Harris G, Scott DJ, Richardson DJ, Butt JN, Clarke TA. Structural modeling of an outer membrane electron conduit from a metal-reducing bacterium suggests electron transfer via periplasmic redox partners. J Biol Chem 2018; 293:8103-8112. [PMID: 29636412 PMCID: PMC5971433 DOI: 10.1074/jbc.ra118.001850] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 03/19/2018] [Indexed: 11/06/2022] Open
Abstract
Many subsurface microorganisms couple their metabolism to the reduction or oxidation of extracellular substrates. For example, anaerobic mineral-respiring bacteria can use external metal oxides as terminal electron acceptors during respiration. Porin-cytochrome complexes facilitate the movement of electrons generated through intracellular catabolic processes across the bacterial outer membrane to these terminal electron acceptors. In the mineral-reducing model bacterium Shewanella oneidensis MR-1, this complex is composed of two decaheme cytochromes (MtrA and MtrC) and an outer-membrane β-barrel (MtrB). However, the structures and mechanisms by which porin-cytochrome complexes transfer electrons are unknown. Here, we used small-angle neutron scattering (SANS) to study the molecular structure of the transmembrane complexes MtrAB and MtrCAB. Ab initio modeling of the scattering data yielded a molecular envelope with dimensions of ∼105 × 60 × 35 Å for MtrAB and ∼170 × 60 × 45 Å for MtrCAB. The shapes of these molecular envelopes suggested that MtrC interacts with the surface of MtrAB, extending ∼70 Å from the membrane surface and allowing the terminal hemes to interact with both MtrAB and an extracellular acceptor. The data also reveal that MtrA fully extends through the length of MtrB, with ∼30 Å being exposed into the periplasm. Proteoliposome models containing membrane-associated MtrCAB and internalized small tetraheme cytochrome (STC) indicate that MtrCAB could reduce Fe(III) citrate with STC as an electron donor, disclosing a direct interaction between MtrCAB and STC. Taken together, both structural and proteoliposome experiments support porin-cytochrome-mediated electron transfer via periplasmic cytochromes such as STC.
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Affiliation(s)
- Marcus J Edwards
- Centre for Molecular and Structural Biochemistry, School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Gaye F White
- Centre for Molecular and Structural Biochemistry, School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Colin W Lockwood
- Centre for Molecular and Structural Biochemistry, School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Matthew C Lawes
- Centre for Molecular and Structural Biochemistry, School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Anne Martel
- Institut Laue-Langevin, 38042 Grenoble, France
| | - Gemma Harris
- Research Complex at Harwell, Rutherford Appleton Laboratory, Oxfordshire OX11 0FA, United Kingdom
| | - David J Scott
- Research Complex at Harwell, Rutherford Appleton Laboratory, Oxfordshire OX11 0FA, United Kingdom; ISIS Spallation Neutron and Muon Source, Rutherford Appleton Laboratory, Oxfordshire OX11 0QX, United Kingdom; School of Biosciences, University of Nottingham, Sutton Bonington Campus, Leicestershire LE12 5RD, United Kingdom
| | - David J Richardson
- Centre for Molecular and Structural Biochemistry, School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Julea N Butt
- Centre for Molecular and Structural Biochemistry, School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Thomas A Clarke
- Centre for Molecular and Structural Biochemistry, School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom.
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White GF, Edwards MJ, Gomez-Perez L, Richardson DJ, Butt JN, Clarke TA. Mechanisms of Bacterial Extracellular Electron Exchange. Adv Microb Physiol 2016; 68:87-138. [PMID: 27134022 DOI: 10.1016/bs.ampbs.2016.02.002] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The biochemical mechanisms by which microbes interact with extracellular soluble metal ions and insoluble redox-active minerals have been the focus of intense research over the last three decades. The process presents two challenges to the microorganism. Firstly, electrons have to be transported at the cell surface, which in Gram-negative bacteria presents an additional problem of electron transfer across the ~6nm of the outer membrane. Secondly, the electrons must be transferred to or from the terminal electron acceptors or donors. This review covers the known mechanisms that bacteria use to transport electrons across the cell envelope to external electron donors/acceptors. In Gram-negative bacteria, electron transfer across the outer membrane involves the use of an outer membrane β-barrel and cytochrome. These can be in the form of a porin-cytochrome protein, such as Cyc2 of Acidithiobacillus ferrooxidans, or a multiprotein porin-cytochrome complex like MtrCAB of Shewanella oneidensis MR-1. For mineral-respiring organisms, there is the additional challenge of transferring the electrons from the cell to mineral surface. For the strict anaerobe Geobacter sulfurreducens this requires electron transfer through conductive pili to associated cytochrome OmcS that directly reduces Fe(III)oxides, while the facultative anaerobe S. oneidensis MR-1 accomplishes mineral reduction through direct membrane contact, contact through filamentous extensions and soluble flavin shuttles, all of which require the outer membrane cytochromes MtrC and OmcA in addition to secreted flavin.
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Affiliation(s)
- G F White
- School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich, United Kingdom
| | - M J Edwards
- School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich, United Kingdom
| | - L Gomez-Perez
- School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich, United Kingdom
| | - D J Richardson
- School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich, United Kingdom
| | - J N Butt
- School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich, United Kingdom
| | - T A Clarke
- School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich, United Kingdom.
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11
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Liu Y, Wang Z, Liu J, Levar C, Edwards MJ, Babauta JT, Kennedy DW, Shi Z, Beyenal H, Bond DR, Clarke TA, Butt JN, Richardson DJ, Rosso KM, Zachara JM, Fredrickson JK, Shi L. A trans-outer membrane porin-cytochrome protein complex for extracellular electron transfer by Geobacter sulfurreducens PCA. ENVIRONMENTAL MICROBIOLOGY REPORTS 2014; 6:776-85. [PMID: 25139405 PMCID: PMC4282303 DOI: 10.1111/1758-2229.12204] [Citation(s) in RCA: 115] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 08/14/2014] [Indexed: 05/19/2023]
Abstract
The multi-heme, outer membrane c-type cytochrome (c-Cyt) OmcB of Geobacter sulfurreducens was previously proposed to mediate electron transfer across the outer membrane. However, the underlying mechanism has remained uncharacterized. In G. sulfurreducens, the omcB gene is part of two tandem four-gene clusters, each is predicted to encode a transcriptional factor (OrfR/OrfS), a porin-like outer membrane protein (OmbB/OmbC), a periplasmic c-type cytochrome (OmaB/OmaC) and an outer membrane c-Cyt (OmcB/OmcC) respectively. Here, we showed that OmbB/OmbC, OmaB/OmaC and OmcB/OmcC of G. sulfurreducens PCA formed the porin-cytochrome (Pcc) protein complexes, which were involved in transferring electrons across the outer membrane. The isolated Pcc protein complexes reconstituted in proteoliposomes transferred electrons from reduced methyl viologen across the lipid bilayer of liposomes to Fe(III)-citrate and ferrihydrite. The pcc clusters were found in all eight sequenced Geobacter and 11 other bacterial genomes from six different phyla, demonstrating a widespread distribution of Pcc protein complexes in phylogenetically diverse bacteria. Deletion of ombB-omaB-omcB-orfS-ombC-omaC-omcC gene clusters had no impact on the growth of G. sulfurreducens PCA with fumarate but diminished the ability of G. sulfurreducens PCA to reduce Fe(III)-citrate and ferrihydrite. Complementation with the ombB-omaB-omcB gene cluster restored the ability of G. sulfurreducens PCA to reduce Fe(III)-citrate and ferrihydrite.
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Affiliation(s)
- Yimo Liu
- Fundamental & Computational Sciences Directorate, Pacific Northwest National LaboratoryRichland, WA, 99352, USA
| | - Zheming Wang
- Fundamental & Computational Sciences Directorate, Pacific Northwest National LaboratoryRichland, WA, 99352, USA
| | - Juan Liu
- Fundamental & Computational Sciences Directorate, Pacific Northwest National LaboratoryRichland, WA, 99352, USA
- † College of Environmental Sciences and Engineering, Peking University, China
| | - Caleb Levar
- Department of Microbiology, University of MinnesotaSt. Paul, MN, 55108, USA
| | - Marcus J Edwards
- Center for Molecular and Structural Biochemistry, School of Biological Sciences and School of Chemistry, University of East AngliaNorwich, NR4 7TJ, UK
| | - Jerome T Babauta
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State UniversityPullman, WA, 99164, USA
| | - David W Kennedy
- Fundamental & Computational Sciences Directorate, Pacific Northwest National LaboratoryRichland, WA, 99352, USA
| | - Zhi Shi
- Fundamental & Computational Sciences Directorate, Pacific Northwest National LaboratoryRichland, WA, 99352, USA
- ‡ Analytical Technology Center, The Dow Chemical Company, Freeport, TX, 77541, USA
| | - Haluk Beyenal
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State UniversityPullman, WA, 99164, USA
| | - Daniel R Bond
- Department of Microbiology, University of MinnesotaSt. Paul, MN, 55108, USA
| | - Thomas A Clarke
- Center for Molecular and Structural Biochemistry, School of Biological Sciences and School of Chemistry, University of East AngliaNorwich, NR4 7TJ, UK
| | - Julea N Butt
- Center for Molecular and Structural Biochemistry, School of Biological Sciences and School of Chemistry, University of East AngliaNorwich, NR4 7TJ, UK
| | - David J Richardson
- Center for Molecular and Structural Biochemistry, School of Biological Sciences and School of Chemistry, University of East AngliaNorwich, NR4 7TJ, UK
| | - Kevin M Rosso
- Fundamental & Computational Sciences Directorate, Pacific Northwest National LaboratoryRichland, WA, 99352, USA
| | - John M Zachara
- Fundamental & Computational Sciences Directorate, Pacific Northwest National LaboratoryRichland, WA, 99352, USA
| | - James K Fredrickson
- Fundamental & Computational Sciences Directorate, Pacific Northwest National LaboratoryRichland, WA, 99352, USA
| | - Liang Shi
- Fundamental & Computational Sciences Directorate, Pacific Northwest National LaboratoryRichland, WA, 99352, USA
- * For correspondence. E-mail ; Tel. 509 371 6967; Fax 509 376 1632
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Electron transport at the microbe-mineral interface: a synthesis of current research challenges. Biochem Soc Trans 2013; 40:1163-6. [PMID: 23176448 DOI: 10.1042/bst20120242] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Many bacterial and archaeal species can couple growth to the respiratory reduction or oxidation of insoluble mineral oxides of transition metals. These solid substrates are abundant electron sinks and sources for life on Earth, but, since they are insoluble in water, they cannot enter the bacterial cells. So, to exploit these electron sinks and sources, specific respiratory electron-transfer mechanisms must overcome the physical limitations associated with electron transfer between a microbe and extracellular metal oxides. Recent microbiological, geochemical, biochemical, spectroscopic and structural work is beginning to shed light on the molecular mechanism and impacts of electron transfer at the microbe-mineral interface from a nanometre to kilometre scale. The research field is attracting attention in applied quarters from those with interests in nanowires, microbial fuel cells, bioremediation and microbial cell factories.
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13
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Rapid electron exchange between surface-exposed bacterial cytochromes and Fe(III) minerals. Proc Natl Acad Sci U S A 2013; 110:6346-51. [PMID: 23538304 DOI: 10.1073/pnas.1220074110] [Citation(s) in RCA: 133] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The mineral-respiring bacterium Shewanella oneidensis uses a protein complex, MtrCAB, composed of two decaheme cytochromes, MtrC and MtrA, brought together inside a transmembrane porin, MtrB, to transport electrons across the outer membrane to a variety of mineral-based electron acceptors. A proteoliposome system containing a pool of internalized electron carriers was used to investigate how the topology of the MtrCAB complex relates to its ability to transport electrons across a lipid bilayer to externally located Fe(III) oxides. With MtrA facing the interior and MtrC exposed on the outer surface of the phospholipid bilayer, the established in vivo orientation, electron transfer from the interior electron carrier pool through MtrCAB to solid-phase Fe(III) oxides was demonstrated. The rates were 10(3) times higher than those reported for reduction of goethite, hematite, and lepidocrocite by S. oneidensis, and the order of the reaction rates was consistent with those observed in S. oneidensis cultures. In contrast, established rates for single turnover reactions between purified MtrC and Fe(III) oxides were 10(3) times lower. By providing a continuous flow of electrons, the proteoliposome experiments demonstrate that conduction through MtrCAB directly to Fe(III) oxides is sufficient to support in vivo, anaerobic, solid-phase iron respiration.
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