1
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Otrin N, Otrin L, Bednarz C, Träger TK, Hamdi F, Kastritis PL, Ivanov I, Sundmacher K. Protein-Rich Rafts in Hybrid Polymer/Lipid Giant Unilamellar Vesicles. Biomacromolecules 2024; 25:778-791. [PMID: 38190609 PMCID: PMC10865357 DOI: 10.1021/acs.biomac.3c00972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 12/20/2023] [Accepted: 12/20/2023] [Indexed: 01/10/2024]
Abstract
Considerable attention has been dedicated to lipid rafts due to their importance in numerous cell functions such as membrane trafficking, polarization, and signaling. Next to studies in living cells, artificial micrometer-sized vesicles with a minimal set of components are established as a major tool to understand the phase separation dynamics and their intimate interplay with membrane proteins. In parallel, mixtures of phospholipids and certain amphiphilic polymers simultaneously offer an interface for proteins and mimic this segregation behavior, presenting a tangible synthetic alternative for fundamental studies and bottom-up design of cellular mimics. However, the simultaneous insertion of complex and sensitive membrane proteins is experimentally challenging and thus far has been largely limited to natural lipids. Here, we present the co-reconstitution of the proton pump bo3 oxidase and the proton consumer ATP synthase in hybrid polymer/lipid giant unilamellar vesicles (GUVs) via fusion/electroformation. Variations of the current method allow for tailored reconstitution protocols and control of the vesicle size. In particular, mixing of protein-free and protein-functionalized nanosized vesicles in the electroformation film results in larger GUVs, while separate reconstitution of the respiratory enzymes enables higher ATP synthesis rates. Furthermore, protein labeling provides a synthetic mechanism for phase separation and protein sequestration, mimicking lipid- and protein-mediated domain formation in nature. The latter means opens further possibilities for re-enacting phenomena like supercomplex assembly or symmetry breaking and enriches the toolbox of bottom-up synthetic biology.
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Affiliation(s)
- Nika Otrin
- Process
Systems Engineering, Max Planck Institute
for Dynamics of Complex Technical Systems, Sandtorstrasse 1, 39106 Magdeburg, Germany
| | - Lado Otrin
- Process
Systems Engineering, Max Planck Institute
for Dynamics of Complex Technical Systems, Sandtorstrasse 1, 39106 Magdeburg, Germany
| | - Claudia Bednarz
- Process
Systems Engineering, Max Planck Institute
for Dynamics of Complex Technical Systems, Sandtorstrasse 1, 39106 Magdeburg, Germany
| | - Toni K. Träger
- Interdisciplinary
Research Center HALOmem and Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Biozentrum, 06120 Halle/Saale, Germany
| | - Farzad Hamdi
- Interdisciplinary
Research Center HALOmem and Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Biozentrum, 06120 Halle/Saale, Germany
| | - Panagiotis L. Kastritis
- Interdisciplinary
Research Center HALOmem and Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Biozentrum, 06120 Halle/Saale, Germany
- Institute
of Chemical Biology, National Hellenic Research
Foundation, 11635 Athens, Greece
| | - Ivan Ivanov
- Process
Systems Engineering, Max Planck Institute
for Dynamics of Complex Technical Systems, Sandtorstrasse 1, 39106 Magdeburg, Germany
- Grup
de Biotecnologia Molecular i Industrial, Department of Chemical Engineering, Universitat Politècnica de Catalunya, Rambla Sant Nebridi 22, 08222 Terrassa, Spain
| | - Kai Sundmacher
- Process
Systems Engineering, Max Planck Institute
for Dynamics of Complex Technical Systems, Sandtorstrasse 1, 39106 Magdeburg, Germany
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2
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Bailoni E, Partipilo M, Coenradij J, Grundel DAJ, Slotboom DJ, Poolman B. Minimal Out-of-Equilibrium Metabolism for Synthetic Cells: A Membrane Perspective. ACS Synth Biol 2023; 12:922-946. [PMID: 37027340 PMCID: PMC10127287 DOI: 10.1021/acssynbio.3c00062] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Indexed: 04/08/2023]
Abstract
Life-like systems need to maintain a basal metabolism, which includes importing a variety of building blocks required for macromolecule synthesis, exporting dead-end products, and recycling cofactors and metabolic intermediates, while maintaining steady internal physical and chemical conditions (physicochemical homeostasis). A compartment, such as a unilamellar vesicle, functionalized with membrane-embedded transport proteins and metabolic enzymes encapsulated in the lumen meets these requirements. Here, we identify four modules designed for a minimal metabolism in a synthetic cell with a lipid bilayer boundary: energy provision and conversion, physicochemical homeostasis, metabolite transport, and membrane expansion. We review design strategies that can be used to fulfill these functions with a focus on the lipid and membrane protein composition of a cell. We compare our bottom-up design with the equivalent essential modules of JCVI-syn3a, a top-down genome-minimized living cell with a size comparable to that of large unilamellar vesicles. Finally, we discuss the bottlenecks related to the insertion of a complex mixture of membrane proteins into lipid bilayers and provide a semiquantitative estimate of the relative surface area and lipid-to-protein mass ratios (i.e., the minimal number of membrane proteins) that are required for the construction of a synthetic cell.
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Affiliation(s)
- Eleonora Bailoni
- Department
of Biochemistry and Molecular Systems Biology, Groningen Biomolecular
Sciences and Biotechnology Institute, University
of Groningen, Nijenborgh
4, 9747 AG Groningen, The Netherlands
| | - Michele Partipilo
- Department
of Biochemistry and Molecular Systems Biology, Groningen Biomolecular
Sciences and Biotechnology Institute, University
of Groningen, Nijenborgh
4, 9747 AG Groningen, The Netherlands
| | - Jelmer Coenradij
- Department
of Biochemistry and Molecular Systems Biology, Groningen Biomolecular
Sciences and Biotechnology Institute, University
of Groningen, Nijenborgh
4, 9747 AG Groningen, The Netherlands
| | - Douwe A. J. Grundel
- Department
of Biochemistry and Molecular Systems Biology, Groningen Biomolecular
Sciences and Biotechnology Institute, University
of Groningen, Nijenborgh
4, 9747 AG Groningen, The Netherlands
| | - Dirk J. Slotboom
- Department
of Biochemistry and Molecular Systems Biology, Groningen Biomolecular
Sciences and Biotechnology Institute, University
of Groningen, Nijenborgh
4, 9747 AG Groningen, The Netherlands
| | - Bert Poolman
- Department
of Biochemistry and Molecular Systems Biology, Groningen Biomolecular
Sciences and Biotechnology Institute, University
of Groningen, Nijenborgh
4, 9747 AG Groningen, The Netherlands
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3
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Park H, Wang W, Min SH, Ren Y, Shin K, Han X. Artificial organelles for sustainable chemical energy conversion and production in artificial cells: Artificial mitochondrion and chloroplasts. BIOPHYSICS REVIEWS 2023; 4:011311. [PMID: 38510162 PMCID: PMC10903398 DOI: 10.1063/5.0131071] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 02/17/2023] [Indexed: 03/22/2024]
Abstract
Sustainable energy conversion modules are the main challenges for building complex reaction cascades in artificial cells. Recent advances in biotechnology have enabled this sustainable energy supply, especially the adenosine triphosphate (ATP), by mimicking the organelles, which are the core structures for energy conversion in living cells. Three components are mainly shared by the artificial organelles: the membrane compartment separating the inner and outer parts, membrane proteins for proton translocation, and the molecular rotary machine for ATP synthesis. Depending on the initiation factors, they are further categorized into artificial mitochondrion and artificial chloroplasts, which use chemical nutrients for oxidative phosphorylation and light for photosynthesis, respectively. In this review, we summarize the essential components needed for artificial organelles and then review the recent progress on two different artificial organelles. Recent strategies, purified and identified proteins, and working principles are discussed. With more study on the artificial mitochondrion and artificial chloroplasts, they are expected to be very powerful tools, allowing us to achieve complex cascading reactions in artificial cells, like the ones that happen in real cells.
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Affiliation(s)
- Hyun Park
- Department of Chemistry and Institute of Biological Interfaces, Sogang University, South Korea
| | - Weichen Wang
- State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, China
| | - Seo Hyeon Min
- Department of Chemistry and Institute of Biological Interfaces, Sogang University, South Korea
| | - Yongshuo Ren
- State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, China
| | - Kwanwoo Shin
- Department of Chemistry and Institute of Biological Interfaces, Sogang University, South Korea
| | - Xiaojun Han
- State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, China
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4
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Hirschi S, Ward TR, Meier WP, Müller DJ, Fotiadis D. Synthetic Biology: Bottom-Up Assembly of Molecular Systems. Chem Rev 2022; 122:16294-16328. [PMID: 36179355 DOI: 10.1021/acs.chemrev.2c00339] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The bottom-up assembly of biological and chemical components opens exciting opportunities to engineer artificial vesicular systems for applications with previously unmet requirements. The modular combination of scaffolds and functional building blocks enables the engineering of complex systems with biomimetic or new-to-nature functionalities. Inspired by the compartmentalized organization of cells and organelles, lipid or polymer vesicles are widely used as model membrane systems to investigate the translocation of solutes and the transduction of signals by membrane proteins. The bottom-up assembly and functionalization of such artificial compartments enables full control over their composition and can thus provide specifically optimized environments for synthetic biological processes. This review aims to inspire future endeavors by providing a diverse toolbox of molecular modules, engineering methodologies, and different approaches to assemble artificial vesicular systems. Important technical and practical aspects are addressed and selected applications are presented, highlighting particular achievements and limitations of the bottom-up approach. Complementing the cutting-edge technological achievements, fundamental aspects are also discussed to cater to the inherently diverse background of the target audience, which results from the interdisciplinary nature of synthetic biology. The engineering of proteins as functional modules and the use of lipids and block copolymers as scaffold modules for the assembly of functionalized vesicular systems are explored in detail. Particular emphasis is placed on ensuring the controlled assembly of these components into increasingly complex vesicular systems. Finally, all descriptions are presented in the greater context of engineering valuable synthetic biological systems for applications in biocatalysis, biosensing, bioremediation, or targeted drug delivery.
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Affiliation(s)
- Stephan Hirschi
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bühlstrasse 28, 3012 Bern, Switzerland.,Molecular Systems Engineering, National Centre of Competence in Research (NCCR), 4002 Basel, Switzerland
| | - Thomas R Ward
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland.,Molecular Systems Engineering, National Centre of Competence in Research (NCCR), 4002 Basel, Switzerland
| | - Wolfgang P Meier
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland.,Molecular Systems Engineering, National Centre of Competence in Research (NCCR), 4002 Basel, Switzerland
| | - Daniel J Müller
- Department of Biosystems Science and Engineering, ETH Zürich, Mattenstrasse 26, 4058 Basel, Switzerland.,Molecular Systems Engineering, National Centre of Competence in Research (NCCR), 4002 Basel, Switzerland
| | - Dimitrios Fotiadis
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bühlstrasse 28, 3012 Bern, Switzerland.,Molecular Systems Engineering, National Centre of Competence in Research (NCCR), 4002 Basel, Switzerland
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5
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Dolder N, Müller P, von Ballmoos C. Experimental platform for the functional investigation of membrane proteins in giant unilamellar vesicles. SOFT MATTER 2022; 18:5877-5893. [PMID: 35916307 PMCID: PMC9364335 DOI: 10.1039/d2sm00551d] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Giant unilamellar vesicles (GUVs) are micrometer-sized model membrane systems that can be viewed directly under the microscope. They serve as scaffolds for the bottom-up creation of synthetic cells, targeted drug delivery and have been widely used to study membrane related phenomena in vitro. GUVs are also of interest for the functional investigation of membrane proteins that carry out many key cellular functions. A major hurdle to a wider application of GUVs in this field is the diversity of existing protocols that are optimized for individual proteins. Here, we compare PVA assisted and electroformation techniques for GUV formation under physiologically relevant conditions, and analyze the effect of immobilization on vesicle structure and membrane tightness towards small substrates and protons. There, differences in terms of yield, size, and leakage of GUVs produced by PVA assisted swelling and electroformation were found, dependent on salt and buffer composition. Using fusion of oppositely charged membranes to reconstitute a model membrane protein, we find that empty vesicles and proteoliposomes show similar fusion behavior, which allows for a rapid estimation of protein incorporation using fluorescent lipids.
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Affiliation(s)
- Nicolas Dolder
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland.
| | - Philipp Müller
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland.
| | - Christoph von Ballmoos
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland.
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6
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Respiratory complex I with charge symmetry in the membrane arm pumps protons. Proc Natl Acad Sci U S A 2022; 119:e2123090119. [PMID: 35759670 PMCID: PMC9271201 DOI: 10.1073/pnas.2123090119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Respiratory complex I is a central enzyme of cellular energy metabolism coupling quinone reduction with proton translocation. Its mechanism, especially concerning proton translocation, remains enigmatic. Three homologous subunits that contain a conserved pattern of charged and polar amino acid residues catalyze proton translocation. Strikingly, the central subunit NuoM contains a conserved glutamate residue at a position where conserved lysine residues are found in the other two subunits, resulting in a charge asymmetry discussed to be essential for proton translocation. We found that the respective glutamate to lysine mutation in Escherichia coli complex I lowers the amount of protons translocated per electron transferred by one-quarter. These data clarify the discussion about possible mechanisms of proton translocation by complex I. Energy-converting NADH:ubiquinone oxidoreductase, respiratory complex I, is essential for cellular energy metabolism coupling NADH oxidation to proton translocation. The mechanism of proton translocation by complex I is still under debate. Its membrane arm contains an unusual central axis of polar and charged amino acid residues connecting the quinone binding site with the antiporter-type subunits NuoL, NuoM, and NuoN, proposed to catalyze proton translocation. Quinone chemistry probably causes conformational changes and electrostatic interactions that are propagated through these subunits by a conserved pattern of predominantly lysine, histidine, and glutamate residues. These conserved residues are thought to transfer protons along and across the membrane arm. The distinct charge distribution in the membrane arm is a prerequisite for proton translocation. Remarkably, the central subunit NuoM contains a conserved glutamate residue in a position that is taken by a lysine residue in the two other antiporter-type subunits. It was proposed that this charge asymmetry is essential for proton translocation, as it should enable NuoM to operate asynchronously with NuoL and NuoN. Accordingly, we exchanged the conserved glutamate in NuoM for a lysine residue, introducing charge symmetry in the membrane arm. The stably assembled variant pumps protons across the membrane, but with a diminished H+/e− stoichiometry of 1.5. Thus, charge asymmetry is not essential for proton translocation by complex I, casting doubts on the suggestion of an asynchronous operation of NuoL, NuoM, and NuoN. Furthermore, our data emphasize the importance of a balanced charge distribution in the protein for directional proton transfer.
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7
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Hoeser F, Weiß M, Friedrich T. The clinically relevant triple mutation in the mtND1 gene inactivates Escherichia coli complex I. FEBS Lett 2022; 596:1124-1132. [PMID: 35234296 DOI: 10.1002/1873-3468.14325] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 02/16/2022] [Accepted: 02/21/2022] [Indexed: 11/07/2022]
Abstract
NADH:ubiquinone oxidoreductase (respiratory complex I) plays a major role in cellular energy metabolism. Complex I deficiencies are the most common cause of mitochondrial dysfunction. Patients suffering from a variety of neurodegenerative diseases carry numerous mutations in the mitochondrially encoded subunits of the complex. The biochemical consequences of these mutations are largely unknown because these genes are difficult to access experimentally. Here, we use Escherichia coli as a model system to characterize the effect of a 7 bp inversion in mtND1 (m.3902-3908inv7) that results in a triple mutation. The triple mutant grew poorly but contained a normal amount of the stably assembled variant. The variant showed no enzymatic activity, which might contribute to the deleterious effect of the mutation in humans.
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Affiliation(s)
- Franziska Hoeser
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104, Freiburg, Germany
| | - Maximilian Weiß
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104, Freiburg, Germany
| | - Thorsten Friedrich
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104, Freiburg, Germany
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8
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Marušič N, Zhao Z, Otrin L, Dimova R, Ivanov I, Sundmacher K. Fusion-Induced Growth of Biomimetic Polymersomes: Behavior of Poly(dimethylsiloxane)-Poly(ethylene oxide) Vesicles in Saline Solutions Under High Agitation. Macromol Rapid Commun 2021; 43:e2100712. [PMID: 34820929 DOI: 10.1002/marc.202100712] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Indexed: 12/16/2022]
Abstract
Giant unilamellar vesicles serve as membrane models and primitive mockups of natural cells. With respect to the latter use, amphiphilic polymers can be used to replace phospholipids in order to introduce certain favorable properties, ultimately allowing for the creation of truly synthetic cells. These new properties also enable the employment of new preparation procedures that are incompatible with the natural amphiphiles. Whereas the growth of lipid compartments to micrometer dimensions has been well established, growth of their synthetic analogs remains underexplored. Here, the influence of experimental parameters like salt type/concentration and magnitude of agitation on the fusion of nanometer-sized vesicles made of poly(dimethylsiloxane)-poly(ethylene oxide) graft copolymer (PDMS-g-PEO) is investigated in detail. To this end, dynamic light scattering, microscopy, and membrane mixing assays are employed, and the process at different time and length scales is analyzed. This optimized method is used as an easy tool to obtain giant vesicles, equipped with membrane and cytosolic biomachinery, in the presence of salts at physiological concentrations.
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Affiliation(s)
- Nika Marušič
- Process Systems Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstraße 1, 39106, Magdeburg, Germany
| | - Ziliang Zhao
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424, Potsdam, Germany.,Leibniz Institute of Photonic Technology e.V., 07745, Jena, Germany.,Faculty of Physics and Astronomy, Institute of Applied Optics and Biophysics, Friedrich Schiller University Jena, 07743, Jena, Germany
| | - Lado Otrin
- Process Systems Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstraße 1, 39106, Magdeburg, Germany
| | - Rumiana Dimova
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424, Potsdam, Germany
| | - Ivan Ivanov
- Process Systems Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstraße 1, 39106, Magdeburg, Germany
| | - Kai Sundmacher
- Process Systems Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstraße 1, 39106, Magdeburg, Germany
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9
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Deutschmann S, Rimle L, von Ballmoos C. Rapid Estimation of Membrane Protein Orientation in Liposomes. Chembiochem 2021; 23:e202100543. [PMID: 34763366 PMCID: PMC9299231 DOI: 10.1002/cbic.202100543] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Revised: 11/11/2021] [Indexed: 11/25/2022]
Abstract
The topological organization of proteins embedded in biological membranes is crucial for the tight interplay between these enzymes and their accessibility to substrates in order to fulfil enzymatic activity. The orientation of a membrane protein reconstituted in artificial membranes depends on many parameters and is hardly predictable. Here, we present a convenient approach to assess this important property independent of the enzymatic activity of the reconstituted protein. Based on cysteine‐specific chemical modification of a target membrane protein with a cyanine fluorophore and a corresponding membrane‐impermeable fluorescence quencher, the novel strategy allows rapid evaluation of the distribution of the two orientations after reconstitution. The assay has been tested for the respiratory complexes bo3 oxidase and ATP synthase of Escherichia coli and the results agree well with other orientation determination approaches. Given the simple procedure, the proposed method is a powerful tool for optimization of reconstitution conditions or quantitative orientation information prior to functional measurements.
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Affiliation(s)
- Sabina Deutschmann
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, 3012, Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, 3012, Bern, Switzerland
| | - Lukas Rimle
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, 3012, Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, 3012, Bern, Switzerland
| | - Christoph von Ballmoos
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, 3012, Bern, Switzerland
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10
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Shim J, Zhou C, Gong T, Iserlis DA, Linjawi HA, Wong M, Pan T, Tan C. Building protein networks in synthetic systems from the bottom-up. Biotechnol Adv 2021; 49:107753. [PMID: 33857631 PMCID: PMC9558565 DOI: 10.1016/j.biotechadv.2021.107753] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 03/18/2021] [Accepted: 04/06/2021] [Indexed: 01/01/2023]
Abstract
The recent development of synthetic biology has expanded the capability to design and construct protein networks outside of living cells from the bottom-up. The new capability has enabled us to assemble protein networks for the basic study of cellular pathways, expression of proteins outside cells, and building tissue materials. Furthermore, the integration of natural and synthetic protein networks has enabled new functions of synthetic or artificial cells. Here, we review the underlying technologies for assembling protein networks in liposomes, water-in-oil droplets, and biomaterials from the bottom-up. We cover the recent applications of protein networks in biological transduction pathways, energy self-supplying systems, cellular environmental sensors, and cell-free protein scaffolds. We also review new technologies for assembling protein networks, including multiprotein purification methods, high-throughput assay screen platforms, and controllable fusion of liposomes. Finally, we present existing challenges towards building protein networks that rival the complexity and dynamic response akin to natural systems. This review addresses the gap in our understanding of synthetic and natural protein networks. It presents a vision towards developing smart and resilient protein networks for various biomedical applications.
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Affiliation(s)
- Jiyoung Shim
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, United States of America
| | - Chuqing Zhou
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, United States of America
| | - Ting Gong
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, United States of America
| | - Dasha Aleksandra Iserlis
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, United States of America
| | - Hamad Abdullah Linjawi
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, United States of America
| | - Matthew Wong
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, United States of America
| | - Tingrui Pan
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, United States of America; Suzhou Institute for Advanced Research, University of Science and Technology, Suzhou, China.
| | - Cheemeng Tan
- Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, United States of America.
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11
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Biochemical consequences of two clinically relevant ND-gene mutations in Escherichia coli respiratory complex I. Sci Rep 2021; 11:12641. [PMID: 34135385 PMCID: PMC8209014 DOI: 10.1038/s41598-021-91631-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 05/28/2021] [Indexed: 11/28/2022] Open
Abstract
NADH:ubiquinone oxidoreductase (respiratory complex I) plays a major role in energy metabolism by coupling electron transfer from NADH to quinone with proton translocation across the membrane. Complex I deficiencies were found to be the most common source of human mitochondrial dysfunction that manifest in a wide variety of neurodegenerative diseases. Seven subunits of human complex I are encoded by mitochondrial DNA (mtDNA) that carry an unexpectedly large number of mutations discovered in mitochondria from patients’ tissues. However, whether or how these genetic aberrations affect complex I at a molecular level is unknown. Here, we used Escherichia coli as a model system to biochemically characterize two mutations that were found in mtDNA of patients. The V253AMT-ND5 mutation completely disturbed the assembly of complex I, while the mutation D199GMT-ND1 led to the assembly of a stable complex capable to catalyze redox-driven proton translocation. However, the latter mutation perturbs quinone reduction leading to a diminished activity. D199MT-ND1 is part of a cluster of charged amino acid residues that are suggested to be important for efficient coupling of quinone reduction and proton translocation. A mechanism considering the role of D199MT-ND1 for energy conservation in complex I is discussed.
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12
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Current problems and future avenues in proteoliposome research. Biochem Soc Trans 2021; 48:1473-1492. [PMID: 32830854 DOI: 10.1042/bst20190966] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 07/10/2020] [Accepted: 07/14/2020] [Indexed: 12/11/2022]
Abstract
Membrane proteins (MPs) are the gatekeepers between different biological compartments separated by lipid bilayers. Being receptors, channels, transporters, or primary pumps, they fulfill a wide variety of cellular functions and their importance is reflected in the increasing number of drugs that target MPs. Functional studies of MPs within a native cellular context, however, is difficult due to the innate complexity of the densely packed membranes. Over the past decades, detergent-based extraction and purification of MPs and their reconstitution into lipid mimetic systems has been a very powerful tool to simplify the experimental system. In this review, we focus on proteoliposomes that have become an indispensable experimental system for enzymes with a vectorial function, including many of the here described energy transducing MPs. We first address long standing questions on the difficulty of successful reconstitution and controlled orientation of MPs into liposomes. A special emphasis is given on coreconstitution of several MPs into the same bilayer. Second, we discuss recent progress in the development of fluorescent dyes that offer sensitive detection with high temporal resolution. Finally, we briefly cover the use of giant unilamellar vesicles for the investigation of complex enzymatic cascades, a very promising experimental tool considering our increasing knowledge of the interplay of different cellular components.
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13
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Kell DB. A protet-based, protonic charge transfer model of energy coupling in oxidative and photosynthetic phosphorylation. Adv Microb Physiol 2021; 78:1-177. [PMID: 34147184 DOI: 10.1016/bs.ampbs.2021.01.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Textbooks of biochemistry will explain that the otherwise endergonic reactions of ATP synthesis can be driven by the exergonic reactions of respiratory electron transport, and that these two half-reactions are catalyzed by protein complexes embedded in the same, closed membrane. These views are correct. The textbooks also state that, according to the chemiosmotic coupling hypothesis, a (or the) kinetically and thermodynamically competent intermediate linking the two half-reactions is the electrochemical difference of protons that is in equilibrium with that between the two bulk phases that the coupling membrane serves to separate. This gradient consists of a membrane potential term Δψ and a pH gradient term ΔpH, and is known colloquially as the protonmotive force or pmf. Artificial imposition of a pmf can drive phosphorylation, but only if the pmf exceeds some 150-170mV; to achieve in vivo rates the imposed pmf must reach 200mV. The key question then is 'does the pmf generated by electron transport exceed 200mV, or even 170mV?' The possibly surprising answer, from a great many kinds of experiment and sources of evidence, including direct measurements with microelectrodes, indicates it that it does not. Observable pH changes driven by electron transport are real, and they control various processes; however, compensating ion movements restrict the Δψ component to low values. A protet-based model, that I outline here, can account for all the necessary observations, including all of those inconsistent with chemiosmotic coupling, and provides for a variety of testable hypotheses by which it might be refined.
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Affiliation(s)
- Douglas B Kell
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative, Biology, University of Liverpool, Liverpool, United Kingdom; The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark.
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14
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Toward sustainable, cell-free biomanufacturing. Curr Opin Biotechnol 2021; 69:136-144. [PMID: 33453438 DOI: 10.1016/j.copbio.2020.12.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 12/10/2020] [Accepted: 12/15/2020] [Indexed: 12/12/2022]
Abstract
Industrial biotechnology is an attractive approach to address the need for low-cost fuels and products from sustainable resources. Unfortunately, cells impose inherent limitations on the effective synthesis and release of target products. One key constraint is that cellular survival objectives often work against the production objectives of biochemical engineers. Additionally, industrial strains release CO2 and struggle to utilize sustainable, potentially profitable feedstocks. Cell-free biotechnology, which uses biological machinery harvested from cells, can address these challenges with advantages including: (i) shorter development times, (ii) higher volumetric production rates, and (iii) tolerance to otherwise toxic molecules. In this review, we highlight recent advances in cell-free technologies toward the production of non-protein products beyond lab-scale demonstrations and describe guiding principles for designing cell-free systems. Specifically, we discuss carbon and energy sources, reaction homeostasis, and scale-up. Expanding the scope of cell-free biomanufacturing practice could enable innovative approaches for the industrial production of green chemicals.
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15
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Jarman OD, Biner O, Hirst J. Regulation of ATP hydrolysis by the ε subunit, ζ subunit and Mg-ADP in the ATP synthase of Paracoccus denitrificans. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1862:148355. [PMID: 33321110 PMCID: PMC8039183 DOI: 10.1016/j.bbabio.2020.148355] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 11/27/2020] [Accepted: 12/08/2020] [Indexed: 12/17/2022]
Abstract
F1FO-ATP synthase is a crucial metabolic enzyme that uses the proton motive force from respiration to regenerate ATP. For maximum thermodynamic efficiency ATP synthesis should be fully reversible, but the enzyme from Paracoccus denitrificans catalyzes ATP hydrolysis at far lower rates than it catalyzes ATP synthesis, an effect often attributed to its unique ζ subunit. Recently, we showed that deleting ζ increases hydrolysis only marginally, indicating that other common inhibitory mechanisms such as inhibition by the C-terminal domain of the ε subunit (ε-CTD) or Mg-ADP may be more important. Here, we created mutants lacking the ε-CTD, and double mutants lacking both the ε-CTD and ζ subunit. No substantial activation of ATP hydrolysis was observed in any of these strains. Instead, hydrolysis in even the double mutant strains could only be activated by oxyanions, the detergent lauryldimethylamine oxide, or a proton motive force, which are all considered to release Mg-ADP inhibition. Our results establish that P. denitrificans ATP synthase is regulated by a combination of the ε and ζ subunits and Mg-ADP inhibition.
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Affiliation(s)
- Owen D Jarman
- The Medical Research Council Mitochondrial Biology Unit, University of Cambridge, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Olivier Biner
- The Medical Research Council Mitochondrial Biology Unit, University of Cambridge, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Judy Hirst
- The Medical Research Council Mitochondrial Biology Unit, University of Cambridge, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK.
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16
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Liu Z, Zhou W, Qi C, Kong T. Interface Engineering in Multiphase Systems toward Synthetic Cells and Organelles: From Soft Matter Fundamentals to Biomedical Applications. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2002932. [PMID: 32954548 DOI: 10.1002/adma.202002932] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 07/19/2020] [Indexed: 06/11/2023]
Abstract
Synthetic cells have a major role in gaining insight into the complex biological processes of living cells; they also give rise to a range of emerging applications from gene delivery to enzymatic nanoreactors. Living cells rely on compartmentalization to orchestrate reaction networks for specialized and coordinated functions. Principally, the compartmentalization has been an essential engineering theme in constructing cell-mimicking systems. Here, efforts to engineer liquid-liquid interfaces of multiphase systems into membrane-bounded and membraneless compartments, which include lipid vesicles, polymer vesicles, colloidosomes, hybrids, and coacervate droplets, are summarized. Examples are provided of how these compartments are designed to imitate biological behaviors or machinery, including molecule trafficking, growth, fusion, energy conversion, intercellular communication, and adaptivity. Subsequently, the state-of-art applications of these cell-inspired synthetic compartments are discussed. Apart from being simplified and cell models for bridging the gap between nonliving matter and cellular life, synthetic compartments also are utilized as intracellular delivery vehicles for nuclei acids and nanoreactors for biochemical synthesis. Finally, key challenges and future directions for achieving the full potential of synthetic cells are highlighted.
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Affiliation(s)
- Zhou Liu
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, Guangdong, 518000, China
| | - Wen Zhou
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, Guangdong, 518000, China
| | - Cheng Qi
- College of Mechatronics and Control Engineering, Shenzhen University, Shenzhen, 518000, China
| | - Tiantian Kong
- Department of Biomedical Engineering, School of Medicine, Shenzhen University, Shenzhen, Guangdong, 518000, China
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17
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Mühlbauer ME, Saura P, Nuber F, Di Luca A, Friedrich T, Kaila VRI. Water-Gated Proton Transfer Dynamics in Respiratory Complex I. J Am Chem Soc 2020; 142:13718-13728. [PMID: 32643371 PMCID: PMC7659035 DOI: 10.1021/jacs.0c02789] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
The respiratory complex I transduces
redox energy into an electrochemical
proton gradient in aerobic respiratory chains, powering energy-requiring
processes in the cell. However, despite recently resolved molecular
structures, the mechanism of this gigantic enzyme remains poorly understood.
By combining large-scale quantum and classical simulations with site-directed
mutagenesis and biophysical experiments, we show here how the conformational
state of buried ion-pairs and water molecules control the protonation
dynamics in the membrane domain of complex I and establish evolutionary
conserved long-range coupling elements. We suggest that an electrostatic
wave propagates in forward and reverse directions across the 200 Å
long membrane domain during enzyme turnover, without significant dissipation
of energy. Our findings demonstrate molecular principles that enable
efficient long-range proton–electron coupling (PCET) and how
perturbation of this PCET machinery may lead to development of mitochondrial
disease.
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Affiliation(s)
- Max E Mühlbauer
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden.,Center for Integrated Protein Science Munich at the Department of Chemistry, Technical University of Munich, Lichtenbergstrasse 4, D85748 Garching, Germany
| | - Patricia Saura
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden.,Center for Integrated Protein Science Munich at the Department of Chemistry, Technical University of Munich, Lichtenbergstrasse 4, D85748 Garching, Germany
| | - Franziska Nuber
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, 79104 Freiburg, Germany
| | - Andrea Di Luca
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden.,Center for Integrated Protein Science Munich at the Department of Chemistry, Technical University of Munich, Lichtenbergstrasse 4, D85748 Garching, Germany
| | - Thorsten Friedrich
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, 79104 Freiburg, Germany
| | - Ville R I Kaila
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden.,Center for Integrated Protein Science Munich at the Department of Chemistry, Technical University of Munich, Lichtenbergstrasse 4, D85748 Garching, Germany
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18
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Wölfer C, Mangold M, Flassig RJ. Towards Design of Self-Organizing Biomimetic Systems. ACTA ACUST UNITED AC 2020; 3:e1800320. [PMID: 32648706 DOI: 10.1002/adbi.201800320] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 02/28/2019] [Indexed: 11/08/2022]
Abstract
The ability of designing biosynthetic systems with well-defined functional biomodules from scratch is an ambitious and revolutionary goal to deliver innovative, engineered solutions to future challenges in biotechnology and process systems engineering. In this work, several key challenges including modularization, functional biomodule identification, and assembly are discussed. In addition, an in silico protocell modeling approach is presented as a foundation for a computational model-based toolkit for rational analysis and modular design of biomimetic systems.
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Affiliation(s)
- Christian Wölfer
- Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstr. 1, 39106, Magdeburg, Germany
| | - Michael Mangold
- University of Applied Sciences Bingen, Berlinstraße 109, 55411, Bingen am Rhein, Germany
| | - Robert J Flassig
- Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstr. 1, 39106, Magdeburg, Germany.,University of Applied Sciences Brandenburg, Magdeburger Str. 50, 14770, Brandenburg an der Havel, Germany
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19
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Marušič N, Otrin L, Zhao Z, Lira RB, Kyrilis FL, Hamdi F, Kastritis PL, Vidaković-Koch T, Ivanov I, Sundmacher K, Dimova R. Constructing artificial respiratory chain in polymer compartments: Insights into the interplay between bo3 oxidase and the membrane. Proc Natl Acad Sci U S A 2020; 117:15006-15017. [PMID: 32554497 PMCID: PMC7334566 DOI: 10.1073/pnas.1919306117] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Cytochrome bo3 ubiquinol oxidase is a transmembrane protein, which oxidizes ubiquinone and reduces oxygen, while pumping protons. Apart from its combination with F1Fo-ATPase to assemble a minimal ATP regeneration module, the utility of the proton pump can be extended to other applications in the context of synthetic cells such as transport, signaling, and control of enzymatic reactions. In parallel, polymers have been speculated to be phospholipid mimics with respect to their ability to self-assemble in compartments with increased stability. However, their usability as interfaces for complex membrane proteins has remained questionable. In the present work, we optimized a fusion/electroformation approach to reconstitute bo3 oxidase in giant unilamellar vesicles made of PDMS-g-PEO and/or phosphatidylcholine (PC). This enabled optical access, while microfluidic trapping allowed for online analysis of individual vesicles. The tight polymer membranes and the inward oriented enzyme caused 1 pH unit difference in 30 min, with an initial rate of 0.35 pH·min-1 To understand the interplay in these composite systems, we studied the relevant mechanical and rheological membrane properties. Remarkably, the proton permeability of polymer/lipid hybrids decreased after protein insertion, while the latter also led to a 20% increase of the polymer diffusion coefficient in polymersomes. In addition, PDMS-g-PEO increased the activity lifetime and the resistance to free radicals. These advantageous properties may open diverse applications, ranging from cell-free biotechnology to biomedicine. Furthermore, the presented study serves as a comprehensive road map for studying the interactions between membrane proteins and synthetic membranes, which will be fundamental for the successful engineering of such hybrid systems.
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Affiliation(s)
- Nika Marušič
- Process Systems Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, 39106 Magdeburg, Germany
| | - Lado Otrin
- Electrochemical Energy Conversion, Max Planck Institute for Dynamics of Complex Technical Systems, 39106 Magdeburg, Germany
| | - Ziliang Zhao
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Rafael B Lira
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Fotis L Kyrilis
- Interdisciplinary Research Center HALOmem, Martin Luther University Halle-Wittenberg, 06120 Halle/Saale, Germany
- Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, 06120 Halle/Saale, Germany
| | - Farzad Hamdi
- Interdisciplinary Research Center HALOmem, Martin Luther University Halle-Wittenberg, 06120 Halle/Saale, Germany
- Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, 06120 Halle/Saale, Germany
| | - Panagiotis L Kastritis
- Interdisciplinary Research Center HALOmem, Martin Luther University Halle-Wittenberg, 06120 Halle/Saale, Germany
- Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, 06120 Halle/Saale, Germany
| | - Tanja Vidaković-Koch
- Electrochemical Energy Conversion, Max Planck Institute for Dynamics of Complex Technical Systems, 39106 Magdeburg, Germany;
| | - Ivan Ivanov
- Process Systems Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, 39106 Magdeburg, Germany;
| | - Kai Sundmacher
- Process Systems Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, 39106 Magdeburg, Germany
| | - Rumiana Dimova
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
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20
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Biner O, Fedor JG, Yin Z, Hirst J. Bottom-Up Construction of a Minimal System for Cellular Respiration and Energy Regeneration. ACS Synth Biol 2020; 9:1450-1459. [PMID: 32383867 PMCID: PMC7611821 DOI: 10.1021/acssynbio.0c00110] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Adenosine triphosphate (ATP), the cellular energy currency, is essential for life. The ability to provide a constant supply of ATP is therefore crucial for the construction of artificial cells in synthetic biology. Here, we describe the bottom-up assembly and characterization of a minimal respiratory system that uses NADH as a fuel to produce ATP from ADP and inorganic phosphate, and is thus capable of sustaining both upstream metabolic processes that rely on NAD+, and downstream energy-demanding processes that are powered by ATP hydrolysis. A detergent-mediated approach was used to co-reconstitute respiratory mitochondrial complex I and an F-type ATP synthase into nanosized liposomes. Addition of the alternative oxidase to the resulting proteoliposomes produced a minimal artificial "organelle" that reproduces the energy-converting catalytic reactions of the mitochondrial respiratory chain: NADH oxidation, ubiquinone cycling, oxygen reduction, proton pumping, and ATP synthesis. As a proof-of-principle, we demonstrate that our nanovesicles are capable of using an NAD+-linked substrate to drive cell-free protein expression. Our nanovesicles are both efficient and durable and may be applied to sustain artificial cells in future work.
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Affiliation(s)
- Olivier Biner
- MRC Mitochondrial Biology Unit, University of Cambridge, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, United Kingdom
| | - Justin G Fedor
- MRC Mitochondrial Biology Unit, University of Cambridge, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, United Kingdom
| | - Zhan Yin
- MRC Mitochondrial Biology Unit, University of Cambridge, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, United Kingdom
| | - Judy Hirst
- MRC Mitochondrial Biology Unit, University of Cambridge, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, United Kingdom
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21
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Morelli AM, Ravera S, Calzia D, Panfoli I. An update of the chemiosmotic theory as suggested by possible proton currents inside the coupling membrane. Open Biol 2020; 9:180221. [PMID: 30966998 PMCID: PMC6501646 DOI: 10.1098/rsob.180221] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Understanding how biological systems convert and store energy is a primary purpose of basic research. However, despite Mitchell's chemiosmotic theory, we are far from the complete description of basic processes such as oxidative phosphorylation (OXPHOS) and photosynthesis. After more than half a century, the chemiosmotic theory may need updating, thanks to the latest structural data on respiratory chain complexes. In particular, up-to date technologies, such as those using fluorescence indicators following proton displacements, have shown that proton translocation is lateral rather than transversal with respect to the coupling membrane. Furthermore, the definition of the physical species involved in the transfer (proton, hydroxonium ion or proton currents) is still an unresolved issue, even though the latest acquisitions support the idea that protonic currents, difficult to measure, are involved. Moreover, FoF1-ATP synthase ubiquitous motor enzyme has the peculiarity (unlike most enzymes) of affecting the thermodynamic equilibrium of ATP synthesis. It seems that the concept of diffusion of the proton charge expressed more than two centuries ago by Theodor von Grotthuss is to be taken into consideration to resolve these issues. All these uncertainties remind us that also in biology it is necessary to consider the Heisenberg indeterminacy principle, which sets limits to analytical questions.
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Affiliation(s)
- Alessandro Maria Morelli
- 1 Pharmacy Department, Biochemistry Lab, University of Genova , Viale Benedetto XV 3, 16132 Genova , Italy
| | - Silvia Ravera
- 2 Experimental Medicine Department, University of Genova , Via De Toni 14, 16132 Genova , Italy
| | - Daniela Calzia
- 1 Pharmacy Department, Biochemistry Lab, University of Genova , Viale Benedetto XV 3, 16132 Genova , Italy
| | - Isabella Panfoli
- 2 Experimental Medicine Department, University of Genova , Via De Toni 14, 16132 Genova , Italy
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22
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Kinetic coupling of the respiratory chain with ATP synthase, but not proton gradients, drives ATP production in cristae membranes. Proc Natl Acad Sci U S A 2020; 117:2412-2421. [PMID: 31964824 DOI: 10.1073/pnas.1917968117] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Mitochondria have a characteristic ultrastructure with invaginations of the inner membrane called cristae that contain the protein complexes of the oxidative phosphorylation system. How this particular morphology of the respiratory membrane impacts energy conversion is currently unknown. One proposed role of cristae formation is to facilitate the establishment of local proton gradients to fuel ATP synthesis. Here, we determined the local pH values at defined sublocations within mitochondria of respiring yeast cells by fusing a pH-sensitive GFP to proteins residing in different mitochondrial subcompartments. Only a small proton gradient was detected over the inner membrane in wild type or cristae-lacking cells. Conversely, the obtained pH values did barely permit ATP synthesis in a reconstituted system containing purified yeast F1F0 ATP synthase, although, thermodynamically, a sufficiently high driving force was applied. At higher driving forces, where robust ATP synthesis was observed, a P-side pH value of 6 increased the ATP synthesis rate 3-fold compared to pH 7. In contrast, when ATP synthase was coreconstituted with an active proton-translocating cytochrome oxidase, ATP synthesis readily occurred at the measured, physiological pH values. Our study thus reveals that the morphology of the inner membrane does not influence the subcompartmental pH values and is not necessary for robust oxidative phosphorylation in mitochondria. Instead, it is likely that the dense packing of the oxidative phosphorylation complexes in the cristae membranes assists kinetic coupling between proton pumping and ATP synthesis.
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23
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Lin J, Weixler D, Daboss S, Seibold GM, Andronescu C, Schuhmann W, Kranz C. Time-resolved ATP measurements during vesicle respiration. Talanta 2019; 205:120083. [PMID: 31450430 DOI: 10.1016/j.talanta.2019.06.083] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 06/20/2019] [Accepted: 06/21/2019] [Indexed: 02/05/2023]
Abstract
In vitro synthesis of ATP catalyzed by the ATP-synthase requires membrane vesicles, in which the ATP-synthase is present within the bilayer membrane. Inverted vesicle prepared from Gram negative cells (e.g., Escherichia coli or Pseudomonas putida) can be readily obtained and used for in vitro ATP-synthesis. Up to now, quantification of ATP synthesized by membrane vesicles has been mostly analyzed via bioluminescence-based assays. Alternatively, vesicle respiration and the associated ATP level can be determined using biosensors, which not only provide high selectivity, but allow ATP measurements without the sample being illuminated. Here, we present a microbiosensor for ATP in combination with scanning electrochemical microscopy (SECM) using an innovative two-compartment electrochemical cell for the determination of ATP levels at E.coli or P. putida inverted vesicles. For a protein concentration of 22 mg/ml, a total amount of 0.29 ± 0.03 μM/μl ATP per vesicle was determined in case of E.coli; in turn, P. putida derived vesicles yielded 0.48 ± 0.02 μM/μl ATP per vesicle at a total protein concentration of 25.2 mg/ml. Inhibition experiments with Venturicidin A clearly revealed that the respiratory chain enzyme complex responsible for ATP generation is effectively involved.
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Affiliation(s)
- Jing Lin
- Institute of Analytical and Bioanalytical Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Dominik Weixler
- Institute of Microbiology and Biotechnology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Sven Daboss
- Institute of Analytical and Bioanalytical Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Gerd M Seibold
- Institute of Microbiology and Biotechnology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany; Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, 2800, Kongens Lyngby, Denmark
| | - Corina Andronescu
- Chemical Technology III, Faculty of Chemistry and Center for Nanointegration (CENIDE), University of Duisburg-Essen, Carl-Benz-Str. 199, 47057, Duisburg, Germany
| | - Wolfgang Schuhmann
- Analytical Chemistry - Center for Electrochemical Sciences (CES), Faculty of Chemistry and Biochemistry, Ruhr University Bochum, 17 Universitätsstr. 150, 44780, Bochum, Germany
| | - Christine Kranz
- Institute of Analytical and Bioanalytical Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany.
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24
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Graf S, Brzezinski P, von Ballmoos C. The proton pumping bo oxidase from Vitreoscilla. Sci Rep 2019; 9:4766. [PMID: 30886219 PMCID: PMC6423279 DOI: 10.1038/s41598-019-40723-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 02/18/2019] [Indexed: 01/31/2023] Open
Abstract
The cytochrome bo3 quinol oxidase from Vitreoscilla (vbo3) catalyses oxidation of ubiquinol and reduction of O2 to H2O. Data from earlier studies suggested that the free energy released in this reaction is used to pump sodium ions instead of protons across a membrane. Here, we have studied the functional properties of heterologously expressed vbo3 with a variety of methods. (i) Following oxygen consumption with a Clark-type electrode, we did not observe a measurable effect of Na+ on the oxidase activity of purified vbo3 solubilized in detergent or reconstituted in liposomes. (ii) Using fluorescent dyes, we find that vbo3 does not pump Na+ ions, but H+ across the membrane, and that H+-pumping is not influenced by the presence of Na+. (iii) Using an oxygen pulse method, it was found that 2 H+/e- are ejected from proteoliposomes, in agreement with the values found for the H+-pumping bo3 oxidase of Escherichia coli (ecbo3). This coincides with the interpretation that 1 H+/e- is pumped across the membrane and 1 H+/e- is released during quinol oxidation. (iv) When the electron transfer kinetics of vbo3 upon reaction with oxygen were followed in single turnover experiments, a similar sequence of reaction steps was observed as reported for the E. coli enzyme and none of these reactions was notably affected by the presence of Na+. Overall the data show that vbo3 is a proton pumping terminal oxidase, behaving similarly to the Escherichia coli bo3 quinol oxidase.
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Affiliation(s)
- Simone Graf
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012, Bern, Switzerland
| | - Peter Brzezinski
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Christoph von Ballmoos
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012, Bern, Switzerland.
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25
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Otrin L, Kleineberg C, Caire da Silva L, Landfester K, Ivanov I, Wang M, Bednarz C, Sundmacher K, Vidaković-Koch T. Artificial Organelles for Energy Regeneration. ACTA ACUST UNITED AC 2019; 3:e1800323. [PMID: 32648709 DOI: 10.1002/adbi.201800323] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Revised: 02/11/2019] [Indexed: 01/03/2023]
Abstract
One of the critical steps in sustaining life-mimicking processes in synthetic cells is energy, i.e., adenosine triphosphate (ATP) regeneration. Previous studies have shown that the simple addition of ATP or ATP regeneration systems, which do not regenerate ATP directly from ADP and Pi , have no or only limited success due to accumulation of ATP hydrolysis products. In general, ATP regeneration can be achieved by converting light or chemical energy into ATP, which may also involve redox transformations of cofactors. The present contribution provides an overview of the existing ATP regeneration strategies and the related nicotinamide adenine dinucleotide (NAD+ ) redox cycling, with a focus on compartmentalized systems. Special attention is being paid to those approaches where so-called artificial organelles are developed. They comprise a semipermeable membrane functionalized by biological or man-made components and employ external energy in the form of light or nutrients in order to generate a transmembrane proton gradient, which is further utilized for ATP synthesis.
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Affiliation(s)
- Lado Otrin
- Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstraße 1, 39106, Magdeburg, Germany
| | - Christin Kleineberg
- Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstraße 1, 39106, Magdeburg, Germany
| | - Lucas Caire da Silva
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Katharina Landfester
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Ivan Ivanov
- Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstraße 1, 39106, Magdeburg, Germany
| | - Minhui Wang
- Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstraße 1, 39106, Magdeburg, Germany
| | - Claudia Bednarz
- Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstraße 1, 39106, Magdeburg, Germany
| | - Kai Sundmacher
- Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstraße 1, 39106, Magdeburg, Germany
| | - Tanja Vidaković-Koch
- Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstraße 1, 39106, Magdeburg, Germany
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26
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Meyrat A, von Ballmoos C. ATP synthesis at physiological nucleotide concentrations. Sci Rep 2019; 9:3070. [PMID: 30816129 PMCID: PMC6395684 DOI: 10.1038/s41598-019-38564-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 12/31/2018] [Indexed: 12/23/2022] Open
Abstract
Synthesis of ATP by the F1F0 ATP synthase in mitochondria and most bacteria is energized by the proton motive force (pmf) established and maintained by respiratory chain enzymes. Conversely, in the presence of ATP and in the absence of a pmf, the enzyme works as an ATP-driven proton pump. Here, we investigate how high concentrations of ATP affect the enzymatic activity of the F1F0 ATP synthase under high pmf conditions, which is the typical situation in mitochondria or growing bacteria. Using the ATP analogue adenosine 5′-O-(1-thiotriphosphate) (ATPαS), we have developed a modified luminescence-based assay to measure ATP synthesis in the presence of millimolar ATP concentrations, replacing an assay using radioactive nucleotides. In inverted membrane vesicles of E. coli, we found that under saturating pmf conditions, ATP synthesis was reduced to ~10% at 5 mM ATPαS. This reduction was reversed by ADP, but not Pi, indicating that the ATP/ADP ratio controls the ATP synthesis rate. Our data suggests that the ATP/ADP ratio ~30 in growing E. coli limits the ATP synthesis rate to ~20% of the maximal rate possible at the applied pmf and that the rate reduction occurs via product inhibition rather than an increased ATP hydrolysis rate.
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Affiliation(s)
- Axel Meyrat
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012, Bern, Switzerland
| | - Christoph von Ballmoos
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012, Bern, Switzerland.
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27
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Fracasso G, Körner Y, Gonzales DTT, Dora Tang TY. In vitro gene expression and detergent-free reconstitution of active proteorhodopsin in lipid vesicles. Exp Biol Med (Maywood) 2019; 244:314-322. [PMID: 30630374 DOI: 10.1177/1535370218820290] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
IMPACT STATEMENT Our results offer the potential for straightforward, additive-free, and molecularly simple routes to building complex bioreactors based on in vitro transcription-translation systems and lipid vesicles.
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Affiliation(s)
- Giorgio Fracasso
- Max-Planck Institute for Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Yvonne Körner
- Max-Planck Institute for Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | | | - T-Y Dora Tang
- Max-Planck Institute for Molecular Cell Biology and Genetics, 01307 Dresden, Germany
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28
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Ahn YO, Albertsson I, Gennis RB, Ädelroth P. Mechanism of proton transfer through the K C proton pathway in the Vibrio cholerae cbb 3 terminal oxidase. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2018; 1859:1191-1198. [PMID: 30251700 PMCID: PMC6260837 DOI: 10.1016/j.bbabio.2018.08.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 08/17/2018] [Accepted: 08/20/2018] [Indexed: 11/17/2022]
Abstract
The heme‑copper oxidases (HCuOs) are terminal components of the respiratory chain, catalyzing oxygen reduction coupled to the generation of a proton motive force. The C-family HCuOs, found in many pathogenic bacteria under low oxygen tension, utilize a single proton uptake pathway to deliver protons both for O2 reduction and for proton pumping. This pathway, called the KC-pathway, starts at Glu-49P in the accessory subunit CcoP, and connects into the catalytic subunit CcoN via the polar residues Tyr-(Y)-227, Asn (N)-293, Ser (S)-244, Tyr (Y)-321 and internal water molecules, and continues to the active site. However, although the residues are known to be functionally important, little is known about the mechanism and dynamics of proton transfer in the KC-pathway. Here, we studied variants of Y227, N293 and Y321. Our results show that in the N293L variant, proton-coupled electron transfer is slowed during single-turnover oxygen reduction, and moreover it shows a pH dependence that is not observed in wildtype. This suggests that there is a shift in the pKa of an internal proton donor into an experimentally accessible range, from >10 in wildtype to ~8.8 in N293L. Furthermore, we show that there are distinct roles for the conserved Y321 and Y227. In Y321F, proton uptake from bulk solution is greatly impaired, whereas Y227F shows wildtype-like rates and retains ~50% turnover activity. These tyrosines have evolutionary counterparts in the K-pathway of B-family HCuOs, but they do not have the same roles, indicating diversity in the proton transfer dynamics in the HCuO superfamily.
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Affiliation(s)
- Young O Ahn
- Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden; Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 S. Mathews Street, Urbana, IL 61801, USA
| | - Ingrid Albertsson
- Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Robert B Gennis
- Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 S. Mathews Street, Urbana, IL 61801, USA
| | - Pia Ädelroth
- Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden.
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29
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Yewdall NA, Mason AF, van Hest JCM. The hallmarks of living systems: towards creating artificial cells. Interface Focus 2018; 8:20180023. [PMID: 30443324 PMCID: PMC6227776 DOI: 10.1098/rsfs.2018.0023] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/29/2018] [Indexed: 01/01/2023] Open
Abstract
Despite the astonishing diversity and complexity of living systems, they all share five common hallmarks: compartmentalization, growth and division, information processing, energy transduction and adaptability. In this review, we give not only examples of how cells satisfy these requirements for life and the ways in which it is possible to emulate these characteristics in engineered platforms, but also the gaps that remain to be bridged. The bottom-up synthesis of life-like systems continues to be driven forward by the advent of new technologies, by the discovery of biological phenomena through their transplantation to experimentally simpler constructs and by providing insights into one of the oldest questions posed by mankind, the origin of life on Earth.
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Affiliation(s)
| | | | - Jan C. M. van Hest
- Eindhoven University of Technology, PO Box 513 (STO 3.31), Eindhoven, MB, The Netherlands
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30
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Scavenging of superoxide by a membrane-bound superoxide oxidase. Nat Chem Biol 2018; 14:788-793. [PMID: 29915379 DOI: 10.1038/s41589-018-0072-x] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 04/05/2018] [Indexed: 01/12/2023]
Abstract
Superoxide is a reactive oxygen species produced during aerobic metabolism in mitochondria and prokaryotes. It causes damage to lipids, proteins and DNA and is implicated in cancer, cardiovascular disease, neurodegenerative disorders and aging. As protection, cells express soluble superoxide dismutases, disproportionating superoxide to oxygen and hydrogen peroxide. Here, we describe a membrane-bound enzyme that directly oxidizes superoxide and funnels the sequestered electrons to ubiquinone in a diffusion-limited reaction. Experiments in proteoliposomes and inverted membranes show that the protein is capable of efficiently quenching superoxide generated at the membrane in vitro. The 2.0 Å crystal structure shows an integral membrane di-heme cytochrome b poised for electron transfer from the P-side and proton uptake from the N-side. This suggests that the reaction is electrogenic and contributes to the membrane potential while also conserving energy by reducing the quinone pool. Based on this enzymatic activity, we propose that the enzyme family be denoted superoxide oxidase (SOO).
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31
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Göpfrich K, Platzman I, Spatz JP. Mastering Complexity: Towards Bottom-up Construction of Multifunctional Eukaryotic Synthetic Cells. Trends Biotechnol 2018; 36:938-951. [PMID: 29685820 PMCID: PMC6100601 DOI: 10.1016/j.tibtech.2018.03.008] [Citation(s) in RCA: 156] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 03/22/2018] [Accepted: 03/23/2018] [Indexed: 12/11/2022]
Abstract
With the ultimate aim to construct a living cell, bottom-up synthetic biology strives to reconstitute cellular phenomena in vitro - disentangled from the complex environment of a cell. Recent work towards this ambitious goal has provided new insights into the mechanisms governing life. With the fast-growing library of functional modules for synthetic cells, their classification and integration become increasingly important. We discuss strategies to reverse-engineer and recombine functional parts for synthetic eukaryotes, mimicking the characteristics of nature's own prototype. Particularly, we focus on large outer compartments, complex endomembrane systems with organelles, and versatile cytoskeletons as hallmarks of eukaryotic life. Moreover, we identify microfluidics and DNA nanotechnology as two technologies that can integrate these functional modules into sophisticated multifunctional synthetic cells.
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Affiliation(s)
- Kerstin Göpfrich
- Max Planck Institute for Medical Research, Department of Cellular Biophysics, Jahnstraße 29, D 69120, Heidelberg, Germany; Department of Biophysical Chemistry, University of Heidelberg, Im Neuenheimer Feld 253, D 69120 Heidelberg, Germany.
| | - Ilia Platzman
- Max Planck Institute for Medical Research, Department of Cellular Biophysics, Jahnstraße 29, D 69120, Heidelberg, Germany; Department of Biophysical Chemistry, University of Heidelberg, Im Neuenheimer Feld 253, D 69120 Heidelberg, Germany.
| | - Joachim P Spatz
- Max Planck Institute for Medical Research, Department of Cellular Biophysics, Jahnstraße 29, D 69120, Heidelberg, Germany; Department of Biophysical Chemistry, University of Heidelberg, Im Neuenheimer Feld 253, D 69120 Heidelberg, Germany.
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32
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Otrin L, Marušič N, Bednarz C, Vidaković-Koch T, Lieberwirth I, Landfester K, Sundmacher K. Toward Artificial Mitochondrion: Mimicking Oxidative Phosphorylation in Polymer and Hybrid Membranes. NANO LETTERS 2017; 17:6816-6821. [PMID: 29067800 DOI: 10.1021/acs.nanolett.7b03093] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
For energy supply to biomimetic constructs, a complex chemical energy-driven ATP-generating artificial system was built. The system was assembled with bottom-up detergent-mediated reconstitution of an ATP synthase and a terminal oxidase into two types of novel nanocontainers, built from either graft copolymer membranes or from hybrid graft copolymer/lipid membranes. The versatility and biocompatibility of the proposed nanocontainers was demonstrated through convenient system assembly and through high retained activity of both membrane-embedded enzymes. In the future, the nanocontainers might be used as a platform for the functional reconstitution of other complex membrane proteins and could considerably expedite the design of nanoreactors, biosensors, and artificial organelles.
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Affiliation(s)
- Lado Otrin
- Max Planck Institute for Dynamics of Complex Technical Systems , Sandtorstrasse 1, 39106 Magdeburg, Germany
| | - Nika Marušič
- Max Planck Institute for Dynamics of Complex Technical Systems , Sandtorstrasse 1, 39106 Magdeburg, Germany
| | - Claudia Bednarz
- Max Planck Institute for Dynamics of Complex Technical Systems , Sandtorstrasse 1, 39106 Magdeburg, Germany
| | - Tanja Vidaković-Koch
- Max Planck Institute for Dynamics of Complex Technical Systems , Sandtorstrasse 1, 39106 Magdeburg, Germany
| | - Ingo Lieberwirth
- Max Planck Institute for Polymer Research , Ackermannweg 10, 55128 Mainz, Germany
| | - Katharina Landfester
- Max Planck Institute for Polymer Research , Ackermannweg 10, 55128 Mainz, Germany
| | - Kai Sundmacher
- Max Planck Institute for Dynamics of Complex Technical Systems , Sandtorstrasse 1, 39106 Magdeburg, Germany
- Otto von Guericke University , Universitaetsplatz 2, 39106 Magdeburg, Germany
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33
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Sjöholm J, Bergstrand J, Nilsson T, Šachl R, Ballmoos CV, Widengren J, Brzezinski P. The lateral distance between a proton pump and ATP synthase determines the ATP-synthesis rate. Sci Rep 2017; 7:2926. [PMID: 28592883 PMCID: PMC5462737 DOI: 10.1038/s41598-017-02836-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 04/19/2017] [Indexed: 11/09/2022] Open
Abstract
We have investigated the effect of lipid composition on interactions between cytochrome bo 3 and ATP-synthase, and the ATP-synthesis activity driven by proton pumping. The two proteins were labeled by fluorescent probes and co-reconstituted in large (d ≅ 100 nm) or giant (d ≅ 10 µm) unilamellar lipid vesicles. Interactions were investigated using fluorescence correlation/cross-correlation spectroscopy and the activity was determined by measuring ATP production, driven by electron-proton transfer, as a function of time. We found that conditions that promoted direct interactions between the two proteins in the membrane (higher fraction DOPC lipids or labeling by hydrophobic molecules) correlated with an increased activity. These data indicate that the ATP-synthesis rate increases with decreasing distance between cytochrome bo 3 and the ATP-synthase, and involves proton transfer along the membrane surface. The maximum distance for lateral proton transfer along the surface was found to be ~80 nm.
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Affiliation(s)
- Johannes Sjöholm
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Jan Bergstrand
- Experimental Biomolecular Physics, Department of Applied Physics, Royal Institute of Technology (KTH), SE-106 91, Stockholm, Sweden
| | - Tobias Nilsson
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Radek Šachl
- Department of Biophysical Chemistry, J. Heyrovský Institute of Physical Chemistry of the A.S.C.R. v.v.i., Prague, Czech Republic
| | | | - Jerker Widengren
- Experimental Biomolecular Physics, Department of Applied Physics, Royal Institute of Technology (KTH), SE-106 91, Stockholm, Sweden
| | - Peter Brzezinski
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden.
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34
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Choi SK, Schurig-Briccio L, Ding Z, Hong S, Sun C, Gennis RB. Location of the Substrate Binding Site of the Cytochrome bo 3 Ubiquinol Oxidase from Escherichia coli. J Am Chem Soc 2017; 139:8346-8354. [PMID: 28538096 DOI: 10.1021/jacs.7b03883] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Cytochrome bo3 is a respiratory proton-pumping oxygen reductase that is a member of the heme-copper superfamily that utilizes ubiquinol-8 (Q8H2) as a substrate. The current consensus model has Q8H2 oxidized at a low affinity site (QL), passing electrons to a tightly bound quinone cofactor at a high affinity site (QH site) that stabilizes the one-electron reduced ubisemiquinone, facilitating the transfer of electrons to the redox active metal centers where O2 is reduced to water. The current work shows that the Q8 bound to the QH site is more dynamic than previously thought. In addition, mutations of residues at the QH site that do not abolish activity have been re-examined and shown to have properties expected of mutations at the substrate binding site (QL): an increase in the KM of the substrate ubiquinol-1 (up to 4-fold) and an increase in the apparent Ki of the inhibitor HQNO (up to 8-fold). The data suggest that there is only one binding site for ubiquinol in cyt bo3 and that site corresponds to the QH site.
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Affiliation(s)
- Sylvia K Choi
- Center for Biophysics and Quantitative Biology, University of Illinois , Urbana, Illinois 61801, United States.,Department of Biochemistry, University of Illinois , Urbana, Illinois 61801, United States
| | - Lici Schurig-Briccio
- Department of Biochemistry, University of Illinois , Urbana, Illinois 61801, United States
| | - Ziqiao Ding
- Department of Biochemistry, University of Illinois , Urbana, Illinois 61801, United States
| | - Sangjin Hong
- Department of Biochemistry, University of Illinois , Urbana, Illinois 61801, United States
| | - Chang Sun
- Department of Biochemistry, University of Illinois , Urbana, Illinois 61801, United States
| | - Robert B Gennis
- Center for Biophysics and Quantitative Biology, University of Illinois , Urbana, Illinois 61801, United States.,Department of Biochemistry, University of Illinois , Urbana, Illinois 61801, United States
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35
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Choi SK, Lin MT, Ouyang H, Gennis RB. Searching for the low affinity ubiquinone binding site in cytochrome bo 3 from Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2017; 1858:366-370. [PMID: 28235459 DOI: 10.1016/j.bbabio.2017.02.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 02/11/2017] [Accepted: 02/14/2017] [Indexed: 11/25/2022]
Abstract
The cytochrome bo3 ubiquinol oxidase is one of three respiratory oxygen reductases in the aerobic respiratory chain of Escherichia coli. The generally accepted model of catalysis assumes that cyt bo3 contains two distinct ubiquinol binding sites: (i) a low affinity (QL) site which is the traditional substrate binding site; and (ii) a high affinity (QH) site where a "permanently" bound quinone acts as a cofactor, taking two electrons from the substrate quinol and passing them one-by-one to the heme b component of the enzyme which, in turn, transfers them to the heme o3/CuB active site. Whereas the residues at the QH site are well defined, the location of the QL site remains unknown. The published X-ray structure does not contain quinone, and substantial amounts of the protein are missing as well. A recent bioinformatics study by Bossis et al. [Biochem J. (2014) 461, 305-314] identified a sequence motif G163EFX3GWX2Y173 as the likely QL site in the family of related quinol oxidases. In the current work, this was tested by site-directed mutagenesis. The results show that these residues are not important for catalytic function and do not define the QL substrate binding site.
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Affiliation(s)
- Sylvia K Choi
- Center for Biophysics and Quantitative Biology, University of Illinois, Urbana, IL 61801, USA
| | - Myat T Lin
- Center for Biophysics and Quantitative Biology, University of Illinois, Urbana, IL 61801, USA
| | - Hanlin Ouyang
- Department of Chemistry, University of Illinois, Urbana, IL 61801, USA
| | - Robert B Gennis
- Center for Biophysics and Quantitative Biology, University of Illinois, Urbana, IL 61801, USA; Department of Chemistry, University of Illinois, Urbana, IL 61801, USA; Department of Biochemistry, University of Illinois, Urbana, IL 61801, USA.
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36
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Regulatory role of the respiratory supercomplex factors in Saccharomyces cerevisiae. Proc Natl Acad Sci U S A 2016; 113:E4476-85. [PMID: 27432958 DOI: 10.1073/pnas.1601196113] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The respiratory supercomplex factors (Rcf) 1 and 2 mediate supramolecular interactions between mitochondrial complexes III (ubiquinol-cytochrome c reductase; cyt. bc1) and IV (cytochrome c oxidase; CytcO). In addition, removal of these polypeptides results in decreased activity of CytcO, but not of cyt. bc1 In the present study, we have investigated the kinetics of ligand binding, the single-turnover reaction of CytcO with O2, and the linked cyt. bc1-CytcO quinol oxidation-oxygen-reduction activities in mitochondria in which Rcf1 or Rcf2 were removed genetically (strains rcf1Δ and rcf2Δ, respectively). The data show that in the rcf1Δ and rcf2Δ strains, in a significant fraction of the population, ligand binding occurs over a time scale that is ∼100-fold faster (τ ≅ 100 μs) than observed with the wild-type mitochondria (τ ≅ 10 ms), indicating structural changes. This effect is specific to removal of Rcf and not dissociation of the cyt. bc1-CytcO supercomplex. Furthermore, in the rcf1Δ and rcf2Δ strains, the single-turnover reaction of CytcO with O2 was incomplete. This observation indicates that the lower activity of CytcO is caused by a fraction of inactive CytcO rather than decreased CytcO activity of the entire population. Furthermore, the data suggest that the Rcf1 polypeptide mediates formation of an electron-transfer bridge from cyt. bc1 to CytcO via a tightly bound cyt. c We discuss the significance of the proposed regulatory mechanism of Rcf1 and Rcf2 in the context of supramolecular interactions between cyt. bc1 and CytcO.
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37
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Biner O, Schick T, Müller Y, von Ballmoos C. Delivery of membrane proteins into small and giant unilamellar vesicles by charge-mediated fusion. FEBS Lett 2016; 590:2051-62. [DOI: 10.1002/1873-3468.12233] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 05/25/2016] [Accepted: 05/27/2016] [Indexed: 12/28/2022]
Affiliation(s)
- Olivier Biner
- Department of Chemistry and Biochemistry; University of Bern; Switzerland
- Graduate School for Cellular and Biomedical Sciences; University of Bern; Switzerland
| | - Thomas Schick
- Department of Chemistry and Biochemistry; University of Bern; Switzerland
- Graduate School for Cellular and Biomedical Sciences; University of Bern; Switzerland
| | - Yannic Müller
- Department of Chemistry and Biochemistry; University of Bern; Switzerland
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38
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Lipid-mediated Protein-protein Interactions Modulate Respiration-driven ATP Synthesis. Sci Rep 2016; 6:24113. [PMID: 27063297 PMCID: PMC4827085 DOI: 10.1038/srep24113] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 03/21/2016] [Indexed: 11/16/2022] Open
Abstract
Energy conversion in biological systems is underpinned by membrane-bound proton
transporters that generate and maintain a proton electrochemical gradient across the
membrane which used, e.g. for generation of ATP by the ATP synthase. Here, we have
co-reconstituted the proton pump cytochrome bo3 (ubiquinol
oxidase) together with ATP synthase in liposomes and studied the effect of changing
the lipid composition on the ATP synthesis activity driven by proton pumping. We
found that for 100 nm liposomes, containing 5 of each proteins, the ATP synthesis
rates decreased significantly with increasing fractions of DOPA, DOPE, DOPG or
cardiolipin added to liposomes made of DOPC; with e.g. 5% DOPG, we observed an
almost 50% decrease in the ATP synthesis rate. However, upon increasing the average
distance between the proton pumps and ATP synthases, the ATP synthesis rate dropped
and the lipid dependence of this activity vanished. The data indicate that protons
are transferred along the membrane, between cytochrome bo3 and the
ATP synthase, but only at sufficiently high protein densities. We also argue that
the local protein density may be modulated by lipid-dependent changes in
interactions between the two proteins complexes, which points to a mechanism by
which the cell may regulate the overall activity of the respiratory chain.
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