1
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Ruppelt D, Ackermann ELM, Robinson T, Steinem C. Assessing the mechanism of facilitated proton transport across GUVs trapped in a microfluidic device. Biophys J 2024:S0006-3495(24)00489-2. [PMID: 39066477 DOI: 10.1016/j.bpj.2024.07.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2024] [Revised: 07/02/2024] [Accepted: 07/22/2024] [Indexed: 07/28/2024] Open
Abstract
Proton transport across lipid membranes is one of the most fundamental reactions that make up living organisms. In vitro, however, the study of proton transport reactions can be very challenging due to limitations imposed by proton concentrations, compartment size, and unstirred layers as well as buffer exchange and buffer capacity. In this study, we have developed a proton permeation assay based on the microfluidic trapping of giant vesicles enclosing the pH-sensitive dye pyranine to address some of these challenges. Time-resolved fluorescence imaging upon a rapid pH shift enabled us to investigate the facilitated H+ permeation mediated by either a channel or a carrier. Specifically, we compared the proton transport rates as a function of different proton gradients of the channel gramicidin D and the proton carrier carbonyl cyanide-m-chlorophenyl hydrazone. Our results demonstrate the efficacy of the assay in monitoring proton transport reactions and distinguishing between a channel-like and a carrier-like mechanism. This groundbreaking result enabled us to elucidate the enigmatic mode of the proton permeation mechanism of the recently discovered natural fibupeptide lugdunin.
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Affiliation(s)
- Dominik Ruppelt
- Institute of Organic and Biomolecular Chemistry, Georg-August Universität Göttingen, Göttingen, Germany
| | - Elena L M Ackermann
- Institute of Organic and Biomolecular Chemistry, Georg-August Universität Göttingen, Göttingen, Germany
| | - Tom Robinson
- Institute for Bioengineering, School of Engineering, University of Edinburgh, Edinburgh, United Kingdom
| | - Claudia Steinem
- Institute of Organic and Biomolecular Chemistry, Georg-August Universität Göttingen, Göttingen, Germany.
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2
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Veit S, Paweletz LC, Günther Pomorski T. Determination of membrane protein orientation upon liposomal reconstitution down to the single vesicle level. Biol Chem 2023; 404:647-661. [PMID: 36857289 DOI: 10.1515/hsz-2022-0325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 02/07/2023] [Indexed: 03/02/2023]
Abstract
Reconstitution of membrane proteins into liposomal membranes represents a key technique in enabling functional analysis under well-defined conditions. In this review, we provide a brief introduction to selected methods that have been developed to determine membrane protein orientation after reconstitution in liposomes, including approaches based on proteolytic digestion with proteases, site-specific labeling, fluorescence quenching and activity assays. In addition, we briefly highlight new strategies based on single vesicle analysis to address the problem of sample heterogeneity.
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Affiliation(s)
- Sarina Veit
- Department of Molecular Biochemistry , Faculty of Chemistry and Biochemistry , NC 7/174, Ruhr University Bochum, Universitätsstraße 150, D-44780 Bochum, Germany
| | - Laura Charlotte Paweletz
- Department of Molecular Biochemistry , Faculty of Chemistry and Biochemistry , NC 7/174, Ruhr University Bochum, Universitätsstraße 150, D-44780 Bochum, Germany
| | - Thomas Günther Pomorski
- Department of Molecular Biochemistry , Faculty of Chemistry and Biochemistry , NC 7/174, Ruhr University Bochum, Universitätsstraße 150, D-44780 Bochum, Germany
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark
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3
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Godoy-Hernandez A, Asseri AH, Purugganan AJ, Jiko C, de Ram C, Lill H, Pabst M, Mitsuoka K, Gerle C, Bald D, McMillan DGG. Rapid and Highly Stable Membrane Reconstitution by LAiR Enables the Study of Physiological Integral Membrane Protein Functions. ACS CENTRAL SCIENCE 2023; 9:494-507. [PMID: 36968527 PMCID: PMC10037447 DOI: 10.1021/acscentsci.2c01170] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Indexed: 06/18/2023]
Abstract
Functional reintegration into lipid environments represents a major challenge for in vitro investigation of integral membrane proteins (IMPs). Here, we report a new approach, termed LMNG Auto-insertion Reintegration (LAiR), for reintegration of IMPs into lipid bilayers within minutes. The resulting proteoliposomes displayed an unprecedented capability to maintain proton gradients and long-term stability. LAiR allowed for monitoring catalysis of a membrane-bound, physiologically relevant polyisoprenoid quinone substrate by Escherichia coli cytochromes bo 3 (cbo 3) and bd (cbd) under control of the proton motive force. LAiR also facilitated bulk-phase detection and physiological assessment of the "proton leak" in cbo 3, a controversial catalytic state that previously was only approachable at the single-molecule level. LAiR maintained the multisubunit integrity and higher-order oligomeric states of the delicate mammalian F-ATP synthase. Given that LAiR can be applied to both liposomes and planar membrane bilayers and is compatible with IMPs and lipids from prokaryotic and eukaryotic sources, we anticipate LAiR to be applied broadly across basic research, pharmaceutical applications, and biotechnology.
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Affiliation(s)
- Albert Godoy-Hernandez
- Department
of Biotechnology, Delft University of Technology, 2628 CD Delft, The Netherlands
| | - Amer H. Asseri
- Biochemistry
Department, Faculty of Science, King Abdulaziz
University, Jeddah 21589, Saudi Arabia
- Amsterdam
Institute for Life and Environment (A-LIFE), AIMMS, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
| | - Aiden J. Purugganan
- Department
of Biotechnology, Delft University of Technology, 2628 CD Delft, The Netherlands
| | - Chimari Jiko
- Institute
for Integrated Radiation and Nuclear Science, Kyoto University, Kyoto, 606-8501, Japan
| | - Carol de Ram
- Department
of Biotechnology, Delft University of Technology, 2628 CD Delft, The Netherlands
| | - Holger Lill
- Amsterdam
Institute for Life and Environment (A-LIFE), AIMMS, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
| | - Martin Pabst
- Department
of Biotechnology, Delft University of Technology, 2628 CD Delft, The Netherlands
| | - Kaoru Mitsuoka
- Research
Center for Ultra-High Voltage Electron Microscopy, Osaka University, Ibaraki, Osaka 565-0871, Japan
| | - Christoph Gerle
- Institute
for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
- Life
Science Research Infrastructure Group, RIKEN
SPring-8 Center, Kouto, Hyogo 679-5148, Japan
| | - Dirk Bald
- Amsterdam
Institute for Life and Environment (A-LIFE), AIMMS, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
| | - Duncan G. G. McMillan
- Department
of Biotechnology, Delft University of Technology, 2628 CD Delft, The Netherlands
- Department
of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, Bunkyo
City, Tokyo 113-8654, Japan
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4
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Rottenberg H. The accelerated evolution of human cytochrome c oxidase - Selection for reduced rate and proton pumping efficiency? BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148595. [PMID: 35850262 DOI: 10.1016/j.bbabio.2022.148595] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 07/02/2022] [Accepted: 07/11/2022] [Indexed: 06/15/2023]
Abstract
The cytochrome c oxidase complex, complex VI (CIV), catalyzes the terminal step of the mitochondrial electron transport chain where the reduction of oxygen to water by cytochrome c is coupled to the generation of a protonmotive force that drive the synthesis of ATP. CIV evolution was greatly accelerated in humans and other anthropoid primates and appears to be driven by adaptive selection. However, it is not known if there are significant functional differences between the anthropoid primates CIV, and other mammals. Comparison of the high-resolution structures of bovine CIV, mouse CIV and human CIV shows structural differences that are associated with anthropoid-specific substitutions. Here I examine the possible effects of these substitutions in four CIV peptides that are known to affect proton pumping: the mtDNA-coded subunits I, II and III, and the nuclear-encoded subunit VIa2. I conclude that many of the anthropoid-specific substitutions could be expected to modulate the rate and/or the efficiency of proton pumping. These results are compatible with the previously proposed hypothesis that the accelerated evolution of CIV in anthropoid primates is driven by selection pressure to lower the mitochondrial protonmotive force and thus decrease the rate of superoxide generation by mitochondria.
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Affiliation(s)
- Hagai Rottenberg
- New Hope Biomedical R&D, 23 W. Bridge Street, New Hope, PA 18938, USA.
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5
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Veit S, Paweletz LC, Bohr SSR, Menon AK, Hatzakis NS, Pomorski TG. Single Vesicle Fluorescence-Bleaching Assay for Multi-Parameter Analysis of Proteoliposomes by Total Internal Reflection Fluorescence Microscopy. ACS APPLIED MATERIALS & INTERFACES 2022; 14:29659-29667. [PMID: 35748880 PMCID: PMC11194769 DOI: 10.1021/acsami.2c07454] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Reconstitution of membrane proteins into model membranes is an essential approach for their functional analysis under chemically defined conditions. Established model-membrane systems used in ensemble average measurements are limited by sample heterogeneity and insufficient knowledge of lipid and protein content at the single vesicle level, which limits quantitative analysis of vesicle properties and prevents their correlation with protein activity. Here, we describe a versatile total internal reflection fluorescence microscopy-based bleaching protocol that permits parallel analysis of multiple parameters (physical size, tightness, unilamellarity, membrane protein content, and orientation) of individual proteoliposomes prepared with fluorescently tagged membrane proteins and lipid markers. The approach makes use of commercially available fluorophores including the commonly used nitrobenzoxadiazole dye and may be applied to deduce functional molecular characteristics of many types of reconstituted fluorescently tagged membrane proteins.
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Affiliation(s)
- Sarina Veit
- Department
of Molecular Biochemistry, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Bochum 44801, Germany
| | - Laura Charlotte Paweletz
- Department
of Molecular Biochemistry, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Bochum 44801, Germany
| | - Søren S.-R. Bohr
- Department
of Chemistry & Nano-Science Center, University of Copenhagen, Copenhagen DK-2100, Denmark
| | - Anant K. Menon
- Department
of Biochemistry, Weill Cornell Medical College, New York, New York 10065, United States
| | - Nikos S. Hatzakis
- Department
of Chemistry & Nano-Science Center, University of Copenhagen, Copenhagen DK-2100, Denmark
- NovoNordisk
Foundation Center for Protein Research,Copenhagen DK-2200, Denmark
| | - Thomas Günther Pomorski
- Department
of Molecular Biochemistry, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Bochum 44801, Germany
- Department
of Plant and Environmental Sciences, University
of Copenhagen,Frederiksberg C DK-1871, Denmark
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6
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Catania R, Machin J, Rappolt M, Muench SP, Beales PA, Jeuken LJC. Detergent-Free Functionalization of Hybrid Vesicles with Membrane Proteins Using SMALPs. Macromolecules 2022; 55:3415-3422. [PMID: 35571225 PMCID: PMC9097535 DOI: 10.1021/acs.macromol.2c00326] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 04/08/2022] [Indexed: 11/28/2022]
Abstract
![]()
Hybrid
vesicles (HVs) that consist of mixtures of block copolymers
and lipids are robust biomimetics of liposomes, providing a valuable
building block in bionanotechnology, catalysis, and synthetic biology.
However, functionalization of HVs with membrane proteins remains laborious
and expensive, creating a significant current challenge in the field.
Here, using a new approach of extraction with styrene-maleic acid
(SMA), we show that a membrane protein (cytochrome bo3) directly transfers into HVs with an efficiency of 73.9
± 13.5% without the requirement of detergent, long incubation
times, or mechanical disruption. Direct transfer of membrane proteins
using this approach was not possible into liposomes, suggesting that
HVs are more amenable than liposomes to membrane protein incorporation
from a SMA lipid particle system. Finally, we show that this transfer
method is not limited to cytochrome bo3 and can also be performed with complex membrane protein mixtures.
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Affiliation(s)
- Rosa Catania
- Astbury Centre of Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, U.K
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, U.K
| | - Jonathan Machin
- Astbury Centre of Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, U.K
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, U.K
| | - Michael Rappolt
- School of Food Science and Nutrition, University of Leeds, Leeds LS2 9JT, U.K
| | - Stephen P. Muench
- Astbury Centre of Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, U.K
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, U.K
| | - Paul A. Beales
- Astbury Centre of Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, U.K
- School of Chemistry, University of Leeds, Leeds LS2 9JT, U.K
| | - Lars J. C. Jeuken
- Astbury Centre of Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, U.K
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, U.K
- Leiden Institute of Chemistry, University Leiden, Leiden 2300RA, The Netherlands
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7
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Malle MG, Löffler PMG, Bohr SSR, Sletfjerding MB, Risgaard NA, Jensen SB, Zhang M, Hedegård P, Vogel S, Hatzakis NS. Single-particle combinatorial multiplexed liposome fusion mediated by DNA. Nat Chem 2022; 14:558-565. [PMID: 35379901 DOI: 10.1038/s41557-022-00912-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 02/17/2022] [Indexed: 12/22/2022]
Abstract
Combinatorial high-throughput methodologies are central for both screening and discovery in synthetic biochemistry and biomedical sciences. They are, however, often reliant on large-scale analyses and thus limited by a long running time and excessive materials cost. We here present a single-particle combinatorial multiplexed liposome fusion mediated by DNA for parallelized multistep and non-deterministic fusion of individual subattolitre nanocontainers. We observed directly the efficient (>93%) and leakage free stochastic fusion sequences for arrays of surface-tethered target liposomes with six freely diffusing populations of cargo liposomes, each functionalized with individual lipidated single-stranded DNA and fluorescently barcoded by a distinct ratio of chromophores. The stochastic fusion resulted in a distinct permutation of fusion sequences for each autonomous nanocontainer. Real-time total internal reflection imaging allowed the direct observation of >16,000 fusions and 566 distinct fusion sequences accurately classified using machine learning. The high-density arrays of surface-tethered target nanocontainers (~42,000 containers per mm2) offers entire combinatorial multiplex screens using only picograms of material.
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Affiliation(s)
- Mette Galsgaard Malle
- Department of Chemistry & Nanoscience Centre, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Foundation Centre for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Philipp M G Löffler
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense, Denmark
| | - Søren S-R Bohr
- Department of Chemistry & Nanoscience Centre, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Foundation Centre for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Magnus Berg Sletfjerding
- Department of Chemistry & Nanoscience Centre, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Foundation Centre for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Simon Bo Jensen
- Department of Chemistry & Nanoscience Centre, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Foundation Centre for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Min Zhang
- Department of Chemistry & Nanoscience Centre, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Foundation Centre for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Per Hedegård
- Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - Stefan Vogel
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense, Denmark.
| | - Nikos S Hatzakis
- Department of Chemistry & Nanoscience Centre, University of Copenhagen, Copenhagen, Denmark. .,Novo Nordisk Foundation Centre for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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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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Borisov VB, Forte E. Impact of Hydrogen Sulfide on Mitochondrial and Bacterial Bioenergetics. Int J Mol Sci 2021; 22:12688. [PMID: 34884491 PMCID: PMC8657789 DOI: 10.3390/ijms222312688] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 11/20/2021] [Accepted: 11/22/2021] [Indexed: 02/06/2023] Open
Abstract
This review focuses on the effects of hydrogen sulfide (H2S) on the unique bioenergetic molecular machines in mitochondria and bacteria-the protein complexes of electron transport chains and associated enzymes. H2S, along with nitric oxide and carbon monoxide, belongs to the class of endogenous gaseous signaling molecules. This compound plays critical roles in physiology and pathophysiology. Enzymes implicated in H2S metabolism and physiological actions are promising targets for novel pharmaceutical agents. The biological effects of H2S are biphasic, changing from cytoprotection to cytotoxicity through increasing the compound concentration. In mammals, H2S enhances the activity of FoF1-ATP (adenosine triphosphate) synthase and lactate dehydrogenase via their S-sulfhydration, thereby stimulating mitochondrial electron transport. H2S serves as an electron donor for the mitochondrial respiratory chain via sulfide quinone oxidoreductase and cytochrome c oxidase at low H2S levels. The latter enzyme is inhibited by high H2S concentrations, resulting in the reversible inhibition of electron transport and ATP production in mitochondria. In the branched respiratory chain of Escherichia coli, H2S inhibits the bo3 terminal oxidase but does not affect the alternative bd-type oxidases. Thus, in E. coli and presumably other bacteria, cytochrome bd permits respiration and cell growth in H2S-rich environments. A complete picture of the impact of H2S on bioenergetics is lacking, but this field is fast-moving, and active ongoing research on this topic will likely shed light on additional, yet unknown biological effects.
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Affiliation(s)
- Vitaliy B. Borisov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, 119991 Moscow, Russia
| | - Elena Forte
- Department of Biochemical Sciences, Sapienza University of Rome, 00185 Rome, Italy;
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10
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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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11
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Streck S, Bohr SSR, Birch D, Rades T, Hatzakis NS, McDowell A, Mørck Nielsen H. Interactions of Cell-Penetrating Peptide-Modified Nanoparticles with Cells Evaluated Using Single Particle Tracking. ACS APPLIED BIO MATERIALS 2021; 4:3155-3165. [DOI: 10.1021/acsabm.0c01563] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Sarah Streck
- School of Pharmacy, University of Otago, Dunedin 9016, New Zealand
| | - Søren S.-R. Bohr
- Department of Chemistry & Nano-science Center, University of Copenhagen, DK-2100 Copenhagen, Denmark
- Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, DK-2100 Copenhagen, Denmark
- Center for Biopharmaceuticals and Biobarriers in Drug Delivery, Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Ditlev Birch
- Center for Biopharmaceuticals and Biobarriers in Drug Delivery, Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Thomas Rades
- Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Nikos S. Hatzakis
- Department of Chemistry & Nano-science Center, University of Copenhagen, DK-2100 Copenhagen, Denmark
- Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, DK-2100 Copenhagen, Denmark
- Center for Biopharmaceuticals and Biobarriers in Drug Delivery, Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Arlene McDowell
- School of Pharmacy, University of Otago, Dunedin 9016, New Zealand
| | - Hanne Mørck Nielsen
- Center for Biopharmaceuticals and Biobarriers in Drug Delivery, Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark
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12
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Biased cytochrome P450-mediated metabolism via small-molecule ligands binding P450 oxidoreductase. Nat Commun 2021; 12:2260. [PMID: 33859207 PMCID: PMC8050233 DOI: 10.1038/s41467-021-22562-w] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 03/15/2021] [Indexed: 02/02/2023] Open
Abstract
Metabolic control is mediated by the dynamic assemblies and function of multiple redox enzymes. A key element in these assemblies, the P450 oxidoreductase (POR), donates electrons and selectively activates numerous (>50 in humans and >300 in plants) cytochromes P450 (CYPs) controlling metabolism of drugs, steroids and xenobiotics in humans and natural product biosynthesis in plants. The mechanisms underlying POR-mediated CYP metabolism remain poorly understood and to date no ligand binding has been described to regulate the specificity of POR. Here, using a combination of computational modeling and functional assays, we identify ligands that dock on POR and bias its specificity towards CYP redox partners, across mammal and plant kingdom. Single molecule FRET studies reveal ligand binding to alter POR conformational sampling, which results in biased activation of metabolic cascades in whole cell assays. We propose the model of biased metabolism, a mechanism akin to biased signaling of GPCRs, where ligand binding on POR stabilizes different conformational states that are linked to distinct metabolic outcomes. Biased metabolism may allow designing pathway-specific therapeutics or personalized food suppressing undesired, disease-related, metabolic pathways.
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13
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Dynamics of Membrane Proteins Monitored by Single-Molecule Fluorescence Across Multiple Timescales. Methods Mol Biol 2021. [PMID: 33582997 DOI: 10.1007/978-1-0716-0724-4_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Single-molecule techniques provide insights into the heterogeneity and dynamics of ensembles and enable the extraction of mechanistic information that is complementary to high-resolution structural techniques. Here, we describe the application of single-molecule Förster resonance energy transfer to study the dynamics of integral membrane protein complexes on timescales spanning sub-milliseconds to minutes (10-9-102 s).
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14
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Guha A, McGuire ML, Leriche G, Yang J, Mayer M. A single-liposome assay that enables temperature-dependent measurement of proton permeability of extremophile-inspired lipid membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183567. [PMID: 33476579 DOI: 10.1016/j.bbamem.2021.183567] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 01/06/2021] [Accepted: 01/12/2021] [Indexed: 10/22/2022]
Affiliation(s)
- Anirvan Guha
- Adolphe Merkle Institute, University of Fribourg, Fribourg, Switzerland
| | - Melissa L McGuire
- Adolphe Merkle Institute, University of Fribourg, Fribourg, Switzerland
| | - Geoffray Leriche
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, United States of America
| | - Jerry Yang
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, United States of America
| | - Michael Mayer
- Adolphe Merkle Institute, University of Fribourg, Fribourg, Switzerland.
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15
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Zhang Y, Sun R, Wang L, Zhu Y, Tuyiringire D, Yang Y, Li K, Han W, Wang Y, Yan L. Physiological responses of Arthrobacter sp. JQ-1 cell interfaces to co-existed di-(2-ethylhexyl) phthalate (DEHP) and copper. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 205:111163. [PMID: 32836159 DOI: 10.1016/j.ecoenv.2020.111163] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 07/20/2020] [Accepted: 08/09/2020] [Indexed: 06/11/2023]
Abstract
Arthrobacter sp. JQ-1 can completely degrade 500 mg/L of DEHP within 3 days. The minimum inhibitory concentrations (MICs) of Cu2+ could reach 1.56 mM, however, 5.0 mg/L Cu2+ apparently inhibited DEHP degradation and bacterial growth. Consequently, JQ-1 was exposed to the DEHP-copper environment to verify the toxicity mechanism based on the physiological responses of cellular multiple interfaces (cellular surface, membrane and intracellular characteristics). The results showed the combination of 500 mg/L DEHP and 5.0 mg/L Cu2+ significantly decreased cell surface hydrophobicity (CSH) and the absolute value of zeta potential, which implied the bioavailability of DEHP was decreased. The cellular surface changes were mainly due to the interaction between Cu2+ and some functional groups (CH2, CH3, aromatic rings, and amide). The weakened proton-motive force (PMF) across the plasma membrane may interfere the formation and utilization of energy, which is not conducive to the repair process of cellular damages. In this study, Non-invasive micro-test technology (NMT) was applied to the research of combined toxicity of DEHP and heavy metal ions for the first time. DEHP-copper intensified K+ efflux and Ca2+ influx across the plasma membrane, which disturbed ion homeostasis of K+ and Ca2+ and might induce apoptosis and further inhibit DEHP degradation. The decline of intracellular esterase activity indicated that the metabolic capacity is apparently restrained. This study enhances our understanding of cellular different interface processes responding to combined pollutants.
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Affiliation(s)
- Ying Zhang
- School of Resources and Environment, Northeast Agricultural University, Harbin, 150030, People's Republic of China.
| | - Ruixue Sun
- School of Resources and Environment, Northeast Agricultural University, Harbin, 150030, People's Republic of China
| | - Lei Wang
- School of Resources and Environment, Northeast Agricultural University, Harbin, 150030, People's Republic of China
| | - Yue Zhu
- School of Resources and Environment, Northeast Agricultural University, Harbin, 150030, People's Republic of China
| | - Diogene Tuyiringire
- School of Resources and Environment, Northeast Agricultural University, Harbin, 150030, People's Republic of China
| | - Ying Yang
- School of Resources and Environment, Northeast Agricultural University, Harbin, 150030, People's Republic of China
| | - Kuimin Li
- School of Resources and Environment, Northeast Agricultural University, Harbin, 150030, People's Republic of China
| | - Wei Han
- School of Resources and Environment, Northeast Agricultural University, Harbin, 150030, People's Republic of China
| | - Yifan Wang
- School of Resources and Environment, Northeast Agricultural University, Harbin, 150030, People's Republic of China
| | - Lilong Yan
- School of Resources and Environment, Northeast Agricultural University, Harbin, 150030, People's Republic of China
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16
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Electrophysiology Measurements of Metal Transport by MntH2 from Enterococcus faecalis. MEMBRANES 2020; 10:membranes10100255. [PMID: 32987882 PMCID: PMC7599946 DOI: 10.3390/membranes10100255] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/16/2020] [Accepted: 09/22/2020] [Indexed: 12/30/2022]
Abstract
Transition metals are essential trace elements and their high-affinity uptake is required for many organisms. Metal transporters are often characterised using metal-sensitive fluorescent dyes, limiting the metals and experimental conditions that can be studied. Here, we have tested whether metal transport by Enterococcus faecalis MntH2 can be measured with an electrophysiology method that is based on the solid-supported membrane technology. E. faecalis MntH2 belongs to the Natural Resistance-Associated Macrophage Protein (Nramp) family of proton-coupled transporters, which transport divalent transition metals and do not transport the earth metals. Electrophysiology confirms transport of Mn(II), Co(II), Zn(II) and Cd(II) by MntH2. However, no uptake responses for Cu(II), Fe(II) and Ni(II) were observed, while the presence of these metals abolishes the uptake signals for Mn(II). Fluorescence assays confirm that Ni(II) is transported. The data are discussed with respect to properties and structures of Nramp-type family members and the ability of electrophysiology to measure charge transport and not directly substrate transport.
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17
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Hugentobler KG, Heinrich D, Berg J, Heberle J, Brzezinski P, Schlesinger R, Block S. Lipid Composition Affects the Efficiency in the Functional Reconstitution of the Cytochrome c Oxidase. Int J Mol Sci 2020; 21:ijms21196981. [PMID: 32977390 PMCID: PMC7583929 DOI: 10.3390/ijms21196981] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 09/15/2020] [Accepted: 09/18/2020] [Indexed: 11/16/2022] Open
Abstract
The transmembrane protein cytochrome c oxidase (CcO) is the terminal oxidase in the respiratory chain of many aerobic organisms and catalyzes the reduction of dioxygen to water. This process maintains an electrochemical proton gradient across the membrane hosting the oxidase. CcO is a well-established model enzyme in bioenergetics to study the proton-coupled electron transfer reactions and protonation dynamics involved in these processes. Its catalytic mechanism is subject to ongoing intense research. Previous research, however, was mainly focused on the turnover of oxygen and electrons in CcO, while studies reporting proton turnover rates of CcO, that is the rate of proton uptake by the enzyme, are scarce. Here, we reconstitute CcO from R. sphaeroides into liposomes containing a pH sensitive dye and probe changes of the pH value inside single proteoliposomes using fluorescence microscopy. CcO proton turnover rates are quantified at the single-enzyme level. In addition, we recorded the distribution of the number of functionally reconstituted CcOs across the proteoliposome population. Studies are performed using proteoliposomes made of native lipid sources, such as a crude extract of soybean lipids and the polar lipid extract of E. coli, as well as purified lipid fractions, such as phosphatidylcholine extracted from soybean lipids. It is shown that these lipid compositions have only minor effects on the CcO proton turnover rate, but can have a strong impact on the reconstitution efficiency of functionally active CcOs. In particular, our experiments indicate that efficient functional reconstitution of CcO is strongly promoted by the addition of anionic lipids like phosphatidylglycerol and cardiolipin.
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Affiliation(s)
- Katharina Gloria Hugentobler
- Institute of Chemistry and Biochemistry, Emmy-Noether Group “Bionanointerfaces”, Freie Universität Berlin, Arnimallee 22, 14195 Berlin, Germany;
| | - Dorothea Heinrich
- Department of Physics, Genetic Biophysics, Freie Universität Berlin, Arnimallee 22, 14195 Berlin, Germany; (D.H.); (R.S.)
| | - Johan Berg
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden; (J.B.); (P.B.)
| | - Joachim Heberle
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Arnimallee 22, 14195 Berlin, Germany;
| | - Peter Brzezinski
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden; (J.B.); (P.B.)
| | - Ramona Schlesinger
- Department of Physics, Genetic Biophysics, Freie Universität Berlin, Arnimallee 22, 14195 Berlin, Germany; (D.H.); (R.S.)
| | - Stephan Block
- Institute of Chemistry and Biochemistry, Emmy-Noether Group “Bionanointerfaces”, Freie Universität Berlin, Arnimallee 22, 14195 Berlin, Germany;
- Correspondence:
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18
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Melin F, Hellwig P. Redox Properties of the Membrane Proteins from the Respiratory Chain. Chem Rev 2020; 120:10244-10297. [DOI: 10.1021/acs.chemrev.0c00249] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Frederic Melin
- Chimie de la Matière Complexe UMR 7140, Laboratoire de Bioelectrochimie et Spectroscopie, CNRS-Université de Strasbourg, 1 rue Blaise Pascal, 67070 Strasbourg, France
| | - Petra Hellwig
- Chimie de la Matière Complexe UMR 7140, Laboratoire de Bioelectrochimie et Spectroscopie, CNRS-Université de Strasbourg, 1 rue Blaise Pascal, 67070 Strasbourg, France
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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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Thomsen RP, Malle MG, Okholm AH, Krishnan S, Bohr SSR, Sørensen RS, Ries O, Vogel S, Simmel FC, Hatzakis NS, Kjems J. A large size-selective DNA nanopore with sensing applications. Nat Commun 2019; 10:5655. [PMID: 31827087 PMCID: PMC6906287 DOI: 10.1038/s41467-019-13284-1] [Citation(s) in RCA: 103] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 10/29/2019] [Indexed: 01/17/2023] Open
Abstract
Transmembrane nanostructures like ion channels and transporters perform key biological functions by controlling flow of molecules across lipid bilayers. Much work has gone into engineering artificial nanopores and applications in selective gating of molecules, label-free detection/sensing of biomolecules and DNA sequencing have shown promise. Here, we use DNA origami to create a synthetic 9 nm wide DNA nanopore, controlled by programmable, lipidated flaps and equipped with a size-selective gating system for the translocation of macromolecules. Successful assembly and insertion of the nanopore into lipid bilayers are validated by transmission electron microscopy (TEM), while selective translocation of cargo and the pore mechanosensitivity are studied using optical methods, including single-molecule, total internal reflection fluorescence (TIRF) microscopy. Size-specific cargo translocation and oligonucleotide-triggered opening of the pore are demonstrated showing that the DNA nanopore can function as a real-time detection system for external signals, offering potential for a variety of highly parallelized sensing applications.
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Affiliation(s)
- Rasmus P Thomsen
- Interdisciplinary Nanoscience Center, Aarhus University, Aarhus C, 8000, Denmark
| | - Mette Galsgaard Malle
- Department of Chemistry & Nanoscience Center, University of Copenhagen, Universitetsparken 5, Copenhagen, 2100, Denmark.,Novo Nordisk Foundation Centre for Protein Research, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen, Denmark
| | - Anders Hauge Okholm
- Interdisciplinary Nanoscience Center, Aarhus University, Aarhus C, 8000, Denmark.,Arla Innovation Centre, Agro Food Park 19, 8200, Aarhus N, Denmark
| | - Swati Krishnan
- Physics Department and ZNN/WSI, Technische Universität München, 85748, Garching, Germany
| | - Søren S-R Bohr
- Department of Chemistry & Nanoscience Center, University of Copenhagen, Universitetsparken 5, Copenhagen, 2100, Denmark.,Novo Nordisk Foundation Centre for Protein Research, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen, Denmark
| | | | - Oliver Ries
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark
| | - Stefan Vogel
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark
| | - Friedrich C Simmel
- Physics Department and ZNN/WSI, Technische Universität München, 85748, Garching, Germany
| | - Nikos S Hatzakis
- Department of Chemistry & Nanoscience Center, University of Copenhagen, Universitetsparken 5, Copenhagen, 2100, Denmark. .,Novo Nordisk Foundation Centre for Protein Research, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen, Denmark.
| | - Jørgen Kjems
- Interdisciplinary Nanoscience Center, Aarhus University, Aarhus C, 8000, Denmark. .,Department of Molecular Biology and Genetics, Aarhus University, Aarhus C, 8000, Denmark.
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21
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Palese LL. Explaining leak states in the proton pump of heme-copper oxidases observed in single-molecule experiments. Biophys Chem 2019; 256:106276. [PMID: 31731070 DOI: 10.1016/j.bpc.2019.106276] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 10/25/2019] [Accepted: 10/27/2019] [Indexed: 11/28/2022]
Abstract
Heme-copper oxidases couple the exergonic oxygen reduction with the endergonic proton translocation. Redox-linked structural changes have been localized in deeply buried regions of the protein, near the low-potential heme. How these movements can modulate distant gating events along the intramolecular proton path, where the entry (exit) of pumped proton occurs, is a major concern for the proton pump models. Generally, these models associate, more or less directly, all translocation events with redox transitions. Although they can account for many phenomenological aspects of the pump, evidences from single-molecules experiments about leak states of the pump represent a formidable challenge. Disconnecting the redox-linked pKa shifts of the proton loading site from the external barriers, we obtain a simple stochastic mechanism which behaves similarly to the real enzyme, able to reverse the flow of the proton transfer.
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22
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Kühnel RM, Grifell-Junyent M, Jørgensen IL, Kemmer GC, Schiller J, Palmgren M, Justesen BH, Günther Pomorski T. Short-chain lipid-conjugated pH sensors for imaging of transporter activities in reconstituted systems and living cells. Analyst 2019; 144:3030-3037. [PMID: 30901016 DOI: 10.1039/c8an02161a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The design of ion sensors has gained importance for the study of ion dynamics in cells, with fluorescent proton nanosensors attracting particular interest because of their applicability in monitoring pH gradients in biological microcompartments and reconstituted membrane systems. In this work, we describe the improved synthesis, photophysical properties and applications of pH sensors based on amine-reactive pHrodo esters and short-chain lipid derivatives of phosphoethanolamine. The major features of these novel probes include strong fluorescence under acidic conditions, efficient partitioning into membranes, and extractability by back exchange to albumin. These features allow for the selective labeling of the inner liposomal leaflet in reconstituted membrane systems for studying proton pumping activities in a quantitative fashion, as demonstrated by assaying the activity of a plant plasma membrane H+-ATPase. Furthermore, the short-chain lipid-conjugated pH sensors enable the monitoring of pH changes from neutral to acidic conditions in the endocytic pathway of living cells. Collectively, our results demonstrate the applicability of short-chain lipid-conjugated sensors for in vivo and in vitro studies and thus pave the way for the design of lipid-conjugated sensors selective to other biologically relevant ions, e.g. calcium and sodium.
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Affiliation(s)
- Ronja Marie Kühnel
- Faculty of Chemistry and Biochemistry, Department of Molecular Biochemistry, Ruhr University Bochum, Universitätstrasse 150, D-44780 Bochum, Germany.
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23
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Schwamborn M, Schumacher J, Sibold J, Teiwes NK, Steinem C. Monitoring ATPase induced pH changes in single proteoliposomes with the lipid-coupled fluorophore Oregon Green 488. Analyst 2018; 142:2670-2677. [PMID: 28616949 DOI: 10.1039/c7an00215g] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Monitoring the proton pumping activity of proteins such as ATPases in reconstituted single proteoliposomes is key to quantify the function of proteins as well as potential proton pump inhibitors. However, most pH-detecting assays available are either not quantitative, require well-adapted reconstitution protocols or are not appropriate for single vesicle studies. Here, we describe the quantitative and time-resolved detection of F-type ATPase-induced pH changes across vesicular membranes doped with the commercially available pH sensitive fluorophore Oregon Green 488 DHPE. This dye is shown to be well suited to monitor acidification of lipid vesicles not only in bulk but also at the single vesicle level. The pKa value of Oregon Green 488 DHPE embedded in a lipid environment was determined to be 6.1 making the fluorophore well suited for a variety of physiologically relevant proton pumps. The TFOF1-ATPase from a thermophilic bacterium was reconstituted into large unilamellar vesicles and the bulk acidification assay clearly reveals the overall activity of the F-type ATPase in the vesicle ensemble with an average pH change of 0.45. However, monitoring the pH changes in individual vesicles attached to a substrate demonstrates that the fraction of vesicles with a significant observable pH change is only about 5%, a number that cannot be gathered from bulk experiments and which is considerably lower than expected.
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Affiliation(s)
- Miriam Schwamborn
- Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstr. 2, 37077 Göttingen, Germany.
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24
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Extremely High Frequency Electromagnetic Fields Facilitate Electrical Signal Propagation by Increasing Transmembrane Potassium Efflux in an Artificial Axon Model. Sci Rep 2018; 8:9299. [PMID: 29915373 PMCID: PMC6006430 DOI: 10.1038/s41598-018-27630-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 05/30/2018] [Indexed: 11/15/2022] Open
Abstract
Among the many biological effects caused by low intensity extremely high frequency electromagnetic fields (EHF-EMF) reported in the literature, those on the nervous system are a promising area for further research. The mechanisms by which these fields alter neural activity are still unclear and thus far there appears to be no frequency dependence regarding neuronal responses. Therefore, proper in vitro models for preliminary screening studies of the interaction between neural cells with EMF are needed. We designed an artificial axon model consisting of a series of parallel RC networks. Each RC network contained an aqueous solution of lipid vesicles with a gradient of potassium (K+) concentration as the functional element. We investigated the effects of EHF-EMF (53.37 GHz–39 mW) on the propagation of the electric impulse. We report that exposure to the EHF-EMF increases the amplitude of electrical signal by inducing a potassium efflux from lipid vesicles. Further, exposure to the EHF-EMF potentiates the action of valinomycin – a K+ carrier – increasing the extent of K+ transport across the lipid membrane. We conclude that exposure to the EHF-EMF facilitates the electrical signal propagation by increasing transmembrane potassium efflux, and that the model presented is promising for future screening studies of different EMF frequency spectrum bands.
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25
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Direct observation of multiple conformational states in Cytochrome P450 oxidoreductase and their modulation by membrane environment and ionic strength. Sci Rep 2018; 8:6817. [PMID: 29717147 PMCID: PMC5931563 DOI: 10.1038/s41598-018-24922-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 04/03/2018] [Indexed: 12/20/2022] Open
Abstract
Cytochrome P450 oxidoreductase (POR) is the primary electron donor in eukaryotic cytochrome P450 (CYP) containing systems. A wealth of ensemble biophysical studies of Cytochrome P450 oxidoreductase (POR) has reported a binary model of the conformational equilibrium directing its catalytic efficiency and biomolecular recognition. In this study, full length POR from the crop plant Sorghum bicolor was site-specifically labeled with Cy3 (donor) and Cy5 (acceptor) fluorophores and reconstituted in nanodiscs. Our single molecule fluorescence resonance energy transfer (smFRET) burst analyses of POR allowed the direct observation and quantification of at least three dominant conformational sub-populations, their distribution and occupancies. Moreover, the state occupancies were remodeled significantly by ionic strength and the nature of reconstitution environment, i.e. phospholipid bilayers (nanodiscs) composed of different lipid head group charges vs. detergent micelles. The existence of conformational heterogeneity in POR may mediate selective activation of multiple downstream electron acceptors and association in complexes in the ER membrane.
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26
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Spherical-supported membranes as platforms for screening against membrane protein targets. Anal Biochem 2018; 549:58-65. [PMID: 29545094 PMCID: PMC5948183 DOI: 10.1016/j.ab.2018.03.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 03/09/2018] [Accepted: 03/12/2018] [Indexed: 11/23/2022]
Abstract
Screening assays performed against membrane protein targets (e.g. phage display) are hampered by issues arising from protein expression and purification, protein stability in detergent solutions and epitope concealment by detergent micelles. Here, we have studied a fast and simple method to improve screening against membrane proteins: spherical-supported bilayer lipid membranes (“SSBLM”). SSBLMs can be quickly isolated via low-speed centrifugation and redispersed in liquid solutions while presenting the target protein in a native-like lipid environment. To provide proof-of-concept, SSBLMs embedding the polytopic bacterial nucleoside transporter NupC were assembled on 100- and 200 nm silica particles. To test specific binding of antibodies, NupC was tagged with a poly-histidine epitope in one of its central loops between two transmembrane helices. Fluorescent labelling, small angle X-ray scattering (SAXS) and cryo-electron microscopy (cryo-EM) were used to monitor formation of the SSBLMs. Specific binding of an anti-his antibody and a gold-nitrilotriacetic acid (NTA) conjugate probe was confirmed with ELISAs and cryo-EM. SSBLMs for screening could be made with purified and lipid reconstituted NupC, as well as crude bacterial membrane extracts. We conclude that SSBLMs are a promising new means of presenting membrane protein targets for (biomimetic) antibody screening in a native-like lipid environment.
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27
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Lundgren A, Fast BJ, Block S, Agnarsson B, Reimhult E, Gunnarsson A, Höök F. Affinity Purification and Single-Molecule Analysis of Integral Membrane Proteins from Crude Cell-Membrane Preparations. NANO LETTERS 2018; 18:381-385. [PMID: 29231738 DOI: 10.1021/acs.nanolett.7b04227] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The function of integral membrane proteins is critically dependent on their naturally surrounding lipid membrane. Detergent-solubilized and purified membrane proteins are therefore often reconstituted into cell-membrane mimics and analyzed for their function with single-molecule microscopy. Expansion of this approach toward a broad range of pharmaceutically interesting drug targets and biomarkers however remains hampered by the fact that these proteins have low expression levels, and that detergent solubilization and reconstitution often cause protein conformational changes and loss of membrane-specific cofactors, which may impair protein function. To overcome this limitation, we here demonstrate how antibody-modified nanoparticles can be used to achieve affinity purification and enrichment of selected integral membrane proteins directly from cell membrane preparations. Nanoparticles were first bound to the ectodomain of β-secretase 1 (BACE1) contained in cell-derived membrane vesicles. In a subsequent step, these were merged into a continuous supported membrane in a microfluidic channel. Through the extended nanoparticle tag, a weak (∼fN) hydrodynamic force could be applied, inducing directed in-membrane movement of targeted BACE1 exclusively. This enabled selective thousand-fold enrichment of the targeted membrane protein while preserving a natural lipid environment. In addition, nanoparticle-targeting also enabled simultaneous tracking analysis of each individual manipulated protein, revealing how their mobility changed when moved from one lipid environment to another. We therefore believe this approach will be particularly useful for separation in-line with single-molecule analysis, eventually opening up for membrane-protein sorting devices analogous to fluorescence-activated cell sorting.
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Affiliation(s)
- Anders Lundgren
- Department of Physics, Chalmers University of Technology , 41296 Göteborg, Sweden
- Department of Nanobiotechnology, University of Natural Resources and Life Sciences , 1190 Vienna, Austria
| | - Björn Johansson Fast
- Department of Physics, Chalmers University of Technology , 41296 Göteborg, Sweden
| | - Stephan Block
- Department of Physics, Chalmers University of Technology , 41296 Göteborg, Sweden
| | - Björn Agnarsson
- Department of Physics, Chalmers University of Technology , 41296 Göteborg, Sweden
| | - Erik Reimhult
- Department of Nanobiotechnology, University of Natural Resources and Life Sciences , 1190 Vienna, Austria
| | - Anders Gunnarsson
- Discovery Sciences, Innovative Medicines and Early Development Biotech Unit, AstraZeneca , 43183 Mölndal, Sweden
| | - Fredrik Höök
- Department of Physics, Chalmers University of Technology , 41296 Göteborg, Sweden
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28
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Li M, Khan S, Rong H, Tuma R, Hatzakis NS, Jeuken LJC. Effects of membrane curvature and pH on proton pumping activity of single cytochrome bo 3 enzymes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2017. [PMID: 28634030 DOI: 10.1016/j.bbabio.2017.06.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The molecular mechanism of proton pumping by heme-copper oxidases (HCO) has intrigued the scientific community since it was first proposed. We have recently reported a novel technology that enables the continuous characterisation of proton transport activity of a HCO and ubiquinol oxidase from Escherichia coli, cytochrome bo3, for hundreds of seconds on the single enzyme level (Li et al. J Am Chem Soc 137 (2015) 16055-16063). Here, we have extended these studies by additional experiments and analyses of the proton transfer rate as a function of proteoliposome size and pH at the N- and P-side of single HCOs. Proton transport activity of cytochrome bo3 was found to decrease with increased curvature of the membrane. Furthermore, proton uptake at the N-side (proton entrance) was insensitive to pH between pH6.4-8.4, while proton release at the P-side had an optimum pH of ~7.4, suggesting that the pH optimum is related to proton release from the proton exit site. Our previous single-enzyme experiments identified rare, long-lived conformation states of cytochrome bo3 where protons leak back under turn-over conditions. Here, we analyzed and found that ~23% of cytochrome bo3 proteoliposomes show ΔpH half-lives below 50s after stopping turnover, while only ~5% of the proteoliposomes containing a non-pumping mutant, E286C cytochrome bo3 exhibit such fast decays. These single-enzyme results confirm our model in which HCO exhibit heterogeneous pumping rates and can adopt rare leak states in which protons are able to rapidly flow back.
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Affiliation(s)
- Mengqiu Li
- School of Biomedical Sciences, University of Leeds, LS2 9JT Leeds, UK
| | - Sanobar Khan
- School of Chemistry, University of Leeds, LS2 9JT Leeds, UK
| | - Honglin Rong
- School of Biomedical Sciences, University of Leeds, LS2 9JT Leeds, UK
| | - Roman Tuma
- School of Molecular and Cellular Biology, University of Leeds, LS2 9JT Leeds, UK
| | - Nikos S Hatzakis
- Nano-Science Center, Department of Chemistry, University of Copenhagen, Copenhagen 2100, Denmark.
| | - Lars J C Jeuken
- School of Biomedical Sciences, University of Leeds, LS2 9JT Leeds, UK.
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Berg J, Block S, Höök F, Brzezinski P. Single Proteoliposomes with E. coli
Quinol Oxidase: Proton Pumping without Transmembrane Leaks. Isr J Chem 2017. [DOI: 10.1002/ijch.201600138] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Johan Berg
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences; Stockholm University; SE-106 91 Stockholm Sweden
| | - Stephan Block
- Department of Physics, Division of Biological Physics; Chalmers University of Technology; Göteborg SE-412 96 Sweden
| | - Fredrik Höök
- Department of Physics, Division of Biological Physics; Chalmers University of Technology; Göteborg SE-412 96 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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30
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Vela S, Bauroth S, Atienza C, Molina-Ontoria A, Guldi DM, Martín N. Determining the Attenuation Factor in Molecular Wires Featuring Covalent and Noncovalent Tectons. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201608973] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Sonia Vela
- Departamento de Química Orgánica I; Facultad de Químicas; Universidad Complutense de Madrid; 28040 Madrid Spain
| | - Stefan Bauroth
- Department of Chemistry and Pharmacy and; Interdisciplinary Center for Molecular Materials; University of Erlangen-Nuremberg; Erlandstrasse 3 91058 Erlangen Germany
| | - Carmen Atienza
- Departamento de Química Orgánica I; Facultad de Químicas; Universidad Complutense de Madrid; 28040 Madrid Spain
| | | | - Dirk M. Guldi
- Department of Chemistry and Pharmacy and; Interdisciplinary Center for Molecular Materials; University of Erlangen-Nuremberg; Erlandstrasse 3 91058 Erlangen Germany
| | - Nazario Martín
- Departamento de Química Orgánica I; Facultad de Químicas; Universidad Complutense de Madrid; 28040 Madrid Spain
- IMDEA-Nanociencia; C/ Faraday 9, Campus UAM 28049 Madrid Spain
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31
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Vela S, Bauroth S, Atienza C, Molina-Ontoria A, Guldi DM, Martín N. Determining the Attenuation Factor in Molecular Wires Featuring Covalent and Noncovalent Tectons. Angew Chem Int Ed Engl 2016; 55:15076-15080. [DOI: 10.1002/anie.201608973] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Indexed: 01/25/2023]
Affiliation(s)
- Sonia Vela
- Departamento de Química Orgánica I; Facultad de Químicas; Universidad Complutense de Madrid; 28040 Madrid Spain
| | - Stefan Bauroth
- Department of Chemistry and Pharmacy and; Interdisciplinary Center for Molecular Materials; University of Erlangen-Nuremberg; Erlandstrasse 3 91058 Erlangen Germany
| | - Carmen Atienza
- Departamento de Química Orgánica I; Facultad de Químicas; Universidad Complutense de Madrid; 28040 Madrid Spain
| | | | - Dirk M. Guldi
- Department of Chemistry and Pharmacy and; Interdisciplinary Center for Molecular Materials; University of Erlangen-Nuremberg; Erlandstrasse 3 91058 Erlangen Germany
| | - Nazario Martín
- Departamento de Química Orgánica I; Facultad de Químicas; Universidad Complutense de Madrid; 28040 Madrid Spain
- IMDEA-Nanociencia; C/ Faraday 9, Campus UAM 28049 Madrid Spain
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32
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Veshaguri S, Christensen SM, Kemmer GC, Ghale G, Møller MP, Lohr C, Christensen AL, Justesen BH, Jørgensen IL, Schiller J, Hatzakis NS, Grabe M, Pomorski TG, Stamou D. Direct observation of proton pumping by a eukaryotic P-type ATPase. Science 2016; 351:1469-73. [PMID: 27013734 DOI: 10.1126/science.aad6429] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 02/23/2016] [Indexed: 12/12/2022]
Abstract
In eukaryotes, P-type adenosine triphosphatases (ATPases) generate the plasma membrane potential and drive secondary transport systems; however, despite their importance, their regulation remains poorly understood. We monitored at the single-molecule level the activity of the prototypic proton-pumping P-type ATPase Arabidopsis thaliana isoform 2 (AHA2). Our measurements, combined with a physical nonequilibrium model of vesicle acidification, revealed that pumping is stochastically interrupted by long-lived (~100 seconds) inactive or leaky states. Allosteric regulation by pH gradients modulated the switch between these states but not the pumping or leakage rates. The autoinhibitory regulatory domain of AHA2 reduced the intrinsic pumping rates but increased the dwell time in the active pumping state. We anticipate that similar functional dynamics underlie the operation and regulation of many other active transporters.
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Affiliation(s)
- Salome Veshaguri
- Bionanotecnology and Nanomedicine Laboratory, University of Copenhagen, Copenhagen, Denmark. Department of Chemistry, University of Copenhagen, Copenhagen, Denmark. Nano-Science Center, University of Copenhagen, Copenhagen, Denmark. Lundbeck Foundation Center Biomembranes in Nanomedicine, University of Copenhagen, Copenhagen, Denmark
| | - Sune M Christensen
- Bionanotecnology and Nanomedicine Laboratory, University of Copenhagen, Copenhagen, Denmark. Department of Chemistry, University of Copenhagen, Copenhagen, Denmark. Nano-Science Center, University of Copenhagen, Copenhagen, Denmark. Lundbeck Foundation Center Biomembranes in Nanomedicine, University of Copenhagen, Copenhagen, Denmark
| | - Gerdi C Kemmer
- Centre for Membrane Pumps in Cells and Disease - PUMPKIN, Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg Denmark
| | - Garima Ghale
- Bionanotecnology and Nanomedicine Laboratory, University of Copenhagen, Copenhagen, Denmark. Department of Chemistry, University of Copenhagen, Copenhagen, Denmark. Nano-Science Center, University of Copenhagen, Copenhagen, Denmark. Lundbeck Foundation Center Biomembranes in Nanomedicine, University of Copenhagen, Copenhagen, Denmark
| | - Mads P Møller
- Bionanotecnology and Nanomedicine Laboratory, University of Copenhagen, Copenhagen, Denmark. Department of Chemistry, University of Copenhagen, Copenhagen, Denmark. Nano-Science Center, University of Copenhagen, Copenhagen, Denmark. Lundbeck Foundation Center Biomembranes in Nanomedicine, University of Copenhagen, Copenhagen, Denmark
| | - Christina Lohr
- Bionanotecnology and Nanomedicine Laboratory, University of Copenhagen, Copenhagen, Denmark. Department of Chemistry, University of Copenhagen, Copenhagen, Denmark. Nano-Science Center, University of Copenhagen, Copenhagen, Denmark. Lundbeck Foundation Center Biomembranes in Nanomedicine, University of Copenhagen, Copenhagen, Denmark
| | - Andreas L Christensen
- Bionanotecnology and Nanomedicine Laboratory, University of Copenhagen, Copenhagen, Denmark. Department of Chemistry, University of Copenhagen, Copenhagen, Denmark. Nano-Science Center, University of Copenhagen, Copenhagen, Denmark. Lundbeck Foundation Center Biomembranes in Nanomedicine, University of Copenhagen, Copenhagen, Denmark
| | - Bo H Justesen
- Centre for Membrane Pumps in Cells and Disease - PUMPKIN, Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg Denmark
| | - Ida L Jørgensen
- Centre for Membrane Pumps in Cells and Disease - PUMPKIN, Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg Denmark
| | - Jürgen Schiller
- Institute of Medical Physics and Biophysics, Faculty of Medicine, University of Leipzig, Leipzig, Germany
| | - Nikos S Hatzakis
- Bionanotecnology and Nanomedicine Laboratory, University of Copenhagen, Copenhagen, Denmark. Department of Chemistry, University of Copenhagen, Copenhagen, Denmark. Nano-Science Center, University of Copenhagen, Copenhagen, Denmark. Lundbeck Foundation Center Biomembranes in Nanomedicine, University of Copenhagen, Copenhagen, Denmark
| | - Michael Grabe
- Cardiovascular Research Institute, Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94143, USA
| | - Thomas Günther Pomorski
- Centre for Membrane Pumps in Cells and Disease - PUMPKIN, Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg Denmark
| | - Dimitrios Stamou
- Bionanotecnology and Nanomedicine Laboratory, University of Copenhagen, Copenhagen, Denmark. Department of Chemistry, University of Copenhagen, Copenhagen, Denmark. Nano-Science Center, University of Copenhagen, Copenhagen, Denmark. Lundbeck Foundation Center Biomembranes in Nanomedicine, University of Copenhagen, Copenhagen, Denmark
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33
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Moses M, Hedegård P, Hatzakis N. Quantification of Functional Dynamics of Membrane Proteins Reconstituted in Nanodiscs Membranes by Single Turnover Functional Readout. Methods Enzymol 2016; 581:227-256. [DOI: 10.1016/bs.mie.2016.08.026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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