1
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Rokitskaya TI, Alekseev AA, Tsybrov FM, Bukhalovich SM, Antonenko YN, Gordeliy VI. Retinal-Based Anion Pump from the Cyanobacterium Tolypothrix campylonemoides. BIOCHEMISTRY. BIOKHIMIIA 2023; 88:1571-1579. [PMID: 38105025 DOI: 10.1134/s0006297923100127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 09/15/2023] [Accepted: 09/15/2023] [Indexed: 12/19/2023]
Abstract
In this work, TcaR rhodopsin from the cyanobacterium Tolypothrix campylonemoides was characterized. Analysis of the amino acid sequence of TcaR revealed that this protein possesses a TSD motif that differs by only one amino acid from the TSA motif of the known halorhodopsin chloride pump. The TcaR protein was expressed in E. coli, purified, and incorporated into proteoliposomes and nanodiscs. Functional activity was measured by electric current generation through the planar bilayer lipid membranes (BLMs) with proteoliposomes adsorbed on one side of the membrane surface, as well as by fluorescence using the voltage-dependent dye oxonol VI. We have shown that TcaR rhodopsin functions as a powerful anion pump. Our results show that the novel microbial anion transporter, TcaR, deserves deeper investigation and may be of interest both for fundamental studies of membrane proteins and as a tool for optogenetics.
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Affiliation(s)
- Tatyana I Rokitskaya
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia.
| | - Aleksey A Alekseev
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141701, Russia
| | - Fedor M Tsybrov
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141701, Russia
| | - Sergej M Bukhalovich
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141701, Russia
| | - Yuri N Antonenko
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia.
| | - Valentin I Gordeliy
- Institut de Biologie Structurale (IBS), Université Grenoble Alpes, CEA, CNRS, Grenoble, France.
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2
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Gorriti MF, Bamann C, Alonso-Reyes DG, Wood P, Bamberg E, Farías ME, Gärtner W, Albarracín VH. Functional characterization of xanthorhodopsin in Salinivibrio socompensis, a novel halophile isolated from modern stromatolites. Photochem Photobiol Sci 2023; 22:1809-1823. [PMID: 37036621 DOI: 10.1007/s43630-023-00412-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 03/21/2023] [Indexed: 04/11/2023]
Abstract
A putative xanthorhodopsin-encoding gene, XR34, was found in the genome of the moderately halophilic gammaproteobacterium Salinivibrio socompensis S34, isolated from modern stromatolites found on the shore of Laguna Socompa (3570 m), Argentina Puna. XR-encoding genes were clustered together with genes encoding X-carotene, retinal (vitamin-A aldehyde), and carotenoid biosynthesis enzymes while the carotene ketolase gene critical for the salinixanthin antenna compound was absent. To identify its functional behavior, we herein overexpressed and characterized this intriguing microbial rhodopsin. Recombinant XR34 showed all the salient features of canonical microbial rhodopsin and covalently bound retinal as a functional chromophore with λmax = 561 nm (εmax ca. 60,000 M-1 cm-1). Two canonical counterions with pK values of around 6 and 3 were identified by pH titration of the recombinant protein. With a recovery time of approximately half an hour in the dark, XR34 shows light-dark adaptation shifting the absorption maximum from 551 to 561 nm. Laser-flash induced photochemistry at pH 9 (deprotonated primary counterion) identified a photocycle starting with a K-like intermediate, followed by an M-state (λmax ca. 400 nm, deprotonated Schiff base), and a final long wavelength-absorbing N- or O-like intermediate before returning to the parental 561 nm-state. Initiating the photocycle at pH 5 (protonated counterion) yields only bathochromic intermediates, due to the lacking capacity of the counterion to accept the Schiff base proton. Illumination of the membrane-embedded protein yielded a capacitive transport current. The presence of the M-intermediate under these conditions was demonstrated by a blue light-induced shunt process.
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Affiliation(s)
- Marta F Gorriti
- Laboratorio de Investigaciones Microbiológicas de Lagunas Andinas (LIMLA), Planta Piloto de Procesos Industriales y Microbiológicos (PROIMI), CCT, CONICET, Av. Belgrano y Pje. Caseros, San Miguel de Tucumán, 4000, Tucumán, Argentina
| | - Christian Bamann
- Max-Planck-Institute for Biophysics, Max-von-Laue-Straße 3, Frankfurt am Main, 60438, Germany
| | - Daniel Gonzalo Alonso-Reyes
- Laboratorio de Microbiología Ultraestructural y Molecular, Centro Integral de Microscopía Electrónica (CIME, CONICET, UNT) CCT, CONICET, Facultad de Agronomía, Zootecnia y Veterinaria, Finca El Manantial, UNT, Camino de Sirga s/n (4107), Yerba Buena, Tucumán, Argentina
- Institute for Analytical Chemistry, University of Leipzig, Johannisallee 29, Leipzig, 04103, Germany
| | - Phillip Wood
- Max-Planck-Institute for Biophysics, Max-von-Laue-Straße 3, Frankfurt am Main, 60438, Germany
| | - Ernst Bamberg
- Max-Planck-Institute for Biophysics, Max-von-Laue-Straße 3, Frankfurt am Main, 60438, Germany
| | - María Eugenia Farías
- Laboratorio de Investigaciones Microbiológicas de Lagunas Andinas (LIMLA), Planta Piloto de Procesos Industriales y Microbiológicos (PROIMI), CCT, CONICET, Av. Belgrano y Pje. Caseros, San Miguel de Tucumán, 4000, Tucumán, Argentina
| | - Wolfgang Gärtner
- Institute for Analytical Chemistry, University of Leipzig, Johannisallee 29, Leipzig, 04103, Germany
| | - Virginia Helena Albarracín
- Laboratorio de Microbiología Ultraestructural y Molecular, Centro Integral de Microscopía Electrónica (CIME, CONICET, UNT) CCT, CONICET, Facultad de Agronomía, Zootecnia y Veterinaria, Finca El Manantial, UNT, Camino de Sirga s/n (4107), Yerba Buena, Tucumán, Argentina.
- Facultad de Ciencias Naturales e Instituto Miguel Lillo, Universidad Nacional de Tucumán, Miguel Lillo 205, San Miguel de Tucumán, 4000, Tucumán, Argentina.
- Facultad de Agronomía, Zootecnia y Veterinaria, Universidad Nacional de Tucumán, Centro Universitario Ing. R. Herrera (Ex Quinta Agronómica), Avda. Pte. N. Kirchner 1900., San Miguel de Tucumán, 4000, Tucumán, Argentina.
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3
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Okhrimenko IS, Kovalev K, Petrovskaya LE, Ilyinsky NS, Alekseev AA, Marin E, Rokitskaya TI, Antonenko YN, Siletsky SA, Popov PA, Zagryadskaya YA, Soloviov DV, Chizhov IV, Zabelskii DV, Ryzhykau YL, Vlasov AV, Kuklin AI, Bogorodskiy AO, Mikhailov AE, Sidorov DV, Bukhalovich S, Tsybrov F, Bukhdruker S, Vlasova AD, Borshchevskiy VI, Dolgikh DA, Kirpichnikov MP, Bamberg E, Gordeliy VI. Mirror proteorhodopsins. Commun Chem 2023; 6:88. [PMID: 37130895 PMCID: PMC10154332 DOI: 10.1038/s42004-023-00884-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 04/12/2023] [Indexed: 05/04/2023] Open
Abstract
Proteorhodopsins (PRs), bacterial light-driven outward proton pumps comprise the first discovered and largest family of rhodopsins, they play a significant role in life on the Earth. A big remaining mystery was that up-to-date there was no described bacterial rhodopsins pumping protons at acidic pH despite the fact that bacteria live in different pH environment. Here we describe conceptually new bacterial rhodopsins which are operating as outward proton pumps at acidic pH. A comprehensive function-structure study of a representative of a new clade of proton pumping rhodopsins which we name "mirror proteorhodopsins", from Sphingomonas paucimobilis (SpaR) shows cavity/gate architecture of the proton translocation pathway rather resembling channelrhodopsins than the known rhodopsin proton pumps. Another unique property of mirror proteorhodopsins is that proton pumping is inhibited by a millimolar concentration of zinc. We also show that mirror proteorhodopsins are extensively represented in opportunistic multidrug resistant human pathogens, plant growth-promoting and zinc solubilizing bacteria. They may be of optogenetic interest.
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Affiliation(s)
- Ivan S Okhrimenko
- Research Center for Molecular Mechanisms of Aging and Age-related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | | | - Lada E Petrovskaya
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, RAS, Moscow, Russia
| | - Nikolay S Ilyinsky
- Research Center for Molecular Mechanisms of Aging and Age-related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - Alexey A Alekseev
- Research Center for Molecular Mechanisms of Aging and Age-related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - Egor Marin
- Research Center for Molecular Mechanisms of Aging and Age-related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
| | - Tatyana I Rokitskaya
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Yuri N Antonenko
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Sergey A Siletsky
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Petr A Popov
- Research Center for Molecular Mechanisms of Aging and Age-related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
- iMolecule, Skolkovo Institute of Science and Technology, Moscow, Russia
| | - Yuliya A Zagryadskaya
- Research Center for Molecular Mechanisms of Aging and Age-related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | | | - Igor V Chizhov
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany
| | | | - Yury L Ryzhykau
- Research Center for Molecular Mechanisms of Aging and Age-related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna, Russia
| | - Alexey V Vlasov
- Research Center for Molecular Mechanisms of Aging and Age-related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna, Russia
| | - Alexander I Kuklin
- Research Center for Molecular Mechanisms of Aging and Age-related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna, Russia
| | - Andrey O Bogorodskiy
- Research Center for Molecular Mechanisms of Aging and Age-related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - Anatolii E Mikhailov
- Research Center for Molecular Mechanisms of Aging and Age-related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - Daniil V Sidorov
- Research Center for Molecular Mechanisms of Aging and Age-related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - Siarhei Bukhalovich
- Research Center for Molecular Mechanisms of Aging and Age-related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - Fedor Tsybrov
- Research Center for Molecular Mechanisms of Aging and Age-related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - Sergey Bukhdruker
- Research Center for Molecular Mechanisms of Aging and Age-related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - Anastasiia D Vlasova
- Research Center for Molecular Mechanisms of Aging and Age-related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - Valentin I Borshchevskiy
- Research Center for Molecular Mechanisms of Aging and Age-related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna, Russia
| | - Dmitry A Dolgikh
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, RAS, Moscow, Russia
- Biological Faculty, Lomonosov Moscow State University, Moscow, Russia
| | - Mikhail P Kirpichnikov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, RAS, Moscow, Russia
- Biological Faculty, Lomonosov Moscow State University, Moscow, Russia
| | - Ernst Bamberg
- Max Planck Institute of Biophysics, Frankfurt am Main, Germany
| | - Valentin I Gordeliy
- Institut de Biologie Structurale (IBS), Université Grenoble Alpes, CNRS, CEA, Grenoble, France.
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4
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Wang D, Wang Y, Li H, Han Y, Hu P, Ma K, Sheves M, Jin Y. Photoactivated Bacteriorhodopsin/SiN x Nanopore-Based Biological Nanofluidic Generator with Single-Protein Sensitivity. ACS NANO 2022; 16:1589-1599. [PMID: 34989239 DOI: 10.1021/acsnano.1c10255] [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] [Indexed: 06/14/2023]
Abstract
Nanofluidics is an emerging hot field that explores the unusual behaviors of ions/molecules transporting through nanoscale channels, which possesses a broad application prospect. However, in situ probing bioactivity of functional proteins on a single-molecule level by a nanofluidic device has not been reported, and it is still a big challenge in the field. Herein, we reported a biological nanofluidic device with a single-protein sensitivity, based on natural proton-pumping protein, bacteriorhodopsin (bR), and a single SiNx nanopore. Nanofluidic single-molecule probing of bR proton-pumping activity and its light response were achieved under applied voltage of 0 V, by biologically self-powered steady-state ionic current nanopore sensing. Green-light irradiation of the device led to the monitoring of a steady-state proton current of ∼3.51 pA/per bR trimer, corresponding to charge density of 815 μC/cm2 generated by each bR monomer, which far exceeded the previously reported value of 1.4 μC/cm2. This finding and method would promote the development of artificial biological and hybrid nanofluidic devices in biosensing and energy conversion applications.
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Affiliation(s)
- Dandan Wang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
- University of Science and Technology of China, Hefei, Anhui 230026, China
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, Zhejiang 321004, China
| | - Yong Wang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
- University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Haijuan Li
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Yanchao Han
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Ping Hu
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
- University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Kongshuo Ma
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
- University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Mordechai Sheves
- Department of Organic Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Yongdong Jin
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
- University of Science and Technology of China, Hefei, Anhui 230026, China
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5
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Abstract
Research on type 1 rhodopsins spans now a history of 50 years. Originally, just archaeal ion pumps and sensors have been discovered. However, with modern genetic techniques and gene sequencing tools, more and more proteins were identified in all kingdoms of life. Spectroscopic and other biophysical studies revealed quite diverse functions. Ion pumps, sensors, and channels are imprinted in the same seven-helix transmembrane protein scaffold carrying a retinal prosthetic group. In this review, molecular biology methods are described, which enabled the elucidation of their function and structure leading to optogenetic applications.
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Affiliation(s)
- Martin Engelhard
- Department Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany.
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6
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Rokitskaya TI, Maliar NL, Siletsky SA, Gordeliy V, Antonenko YN. Electrophysiological Characterization of Microbial Rhodopsin Transport Properties: Electrometric and ΔpH Measurements Using Planar Lipid Bilayer, Collodion Film, and Fluorescent Probe Approaches. Methods Mol Biol 2022; 2501:259-275. [PMID: 35857232 DOI: 10.1007/978-1-0716-2329-9_12] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Electrophysiological approaches to the study of the activity of retinal-containing protein bacteriorhodopsin (bR) or other proteins of this family are based usually on measurements of electrical current through a planar bilayer lipid membrane (BLM) with proteoliposomes attached to the BLM surface at one side of the membrane. Here, we describe the measurements of the pumping activity of bR and channelrhodopsin 2 (ChR2) with special attention to the study of voltage dependence of the light-induced currents. Strong voltage dependence of ChR2 suggests light-triggered ion channel activity of ChR2. We also describe electrophysiological measurements with the help of collodion film instead of BLM for the measurements of fast stages of a rhodopsin photocycle as well as the estimation of the activity of proteoliposomes without a macro membrane using fluorescent probes such as oxonol VI or 9-aminoacridine.
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Affiliation(s)
- Tatyana I Rokitskaya
- Department of Bioenergetics, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Nina L Maliar
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology (National Research University), Dolgoprudny, Russia
| | - Sergey A Siletsky
- Department of Molecular Energetics of Microorganisms, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Valentin Gordeliy
- Institut de Biologie Structurale (IBS), Université Grenoble Alpes, CEA, CNRS, Grenoble, France
| | - Yuri N Antonenko
- Department of Bioenergetics, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia.
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7
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Rokitskaya TI, Maliar N, Kovalev KV, Volkov O, Gordeliy VI, Antonenko YN. Rhodopsin Channel Activity Can Be Evaluated by Measuring the Photocurrent Voltage Dependence in Planar Bilayer Lipid Membranes. BIOCHEMISTRY (MOSCOW) 2021; 86:409-419. [PMID: 33941063 DOI: 10.1134/s0006297921040039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The studies of the functional properties of retinal-containing proteins often include experiments in model membrane systems, e.g., measurements of electric current through planar bilayer lipid membranes (BLMs) with proteoliposomes adsorbed on one of the membrane surfaces. However, the possibilities of this method have not been fully explored yet. We demonstrated that the voltage dependence of stationary photocurrents for two light-sensitive proteins, bacteriorhodopsin (bR) and channelrhodopsin 2 (ChR2), in the presence of protonophore had very different characteristics. In the case of the bR (proton pump), the photocurrent through the BLM did not change direction when the polarity of the applied voltage was switched. In the case of the photosensitive channel protein ChR2, the photocurrent increased with the increase in voltage and the current polarity changed with the change in the voltage polarity. The protonophore 4,5,6,7-tetrachloro-2-trifluoromethyl benzimidazole (TTFB) was more efficient in the maximizing stationary photocurrents. In the presence of carbonyl cyanide-m-chlorophenylhydrazone (CCCP), the amplitude of the measured photocurrents for bR significantly decreased, while in the case of ChR2, the photocurrents virtually disappeared. The difference between the effects of TTFB and CCCP was apparently due to the fact that, in contrast to TTFB, CCCP transfers protons across the liposome membranes with a higher rate than through the decane-containing BLM used as a surface for the proteoliposome adsorption.
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Affiliation(s)
- Tatyana I Rokitskaya
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia.
| | - Nina Maliar
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141701, Russia
| | - Kirill V Kovalev
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141701, Russia.,Institut de Biologie Structurale (IBS), Université Grenoble Alpes, CEA, CNRS, Grenoble, 38044, France
| | - Oleksandr Volkov
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich GmbH, Juelich, 52425, Germany.,JuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich GmbH, Juelich, 52425, Germany
| | - Valentin I Gordeliy
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141701, Russia.,Institut de Biologie Structurale (IBS), Université Grenoble Alpes, CEA, CNRS, Grenoble, 38044, France.,Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich GmbH, Juelich, 52425, Germany.,JuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich GmbH, Juelich, 52425, Germany
| | - Yuri N Antonenko
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
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8
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Berselli G, Gimenez A, O’Connor A, Keyes TE. Robust Photoelectric Biomolecular Switch at a Microcavity-Supported Lipid Bilayer. ACS APPLIED MATERIALS & INTERFACES 2021; 13:29158-29169. [PMID: 34121400 PMCID: PMC8289237 DOI: 10.1021/acsami.1c06798] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 06/01/2021] [Indexed: 05/08/2023]
Abstract
Biomolecular devices based on photo-responsive proteins have been widely proposed for medical, electrical, and energy storage and production applications. Also, bacteriorhodopsin (bR) has been extensively applied in such prospective devices as a robust photo addressable proton pump. As it is a membrane protein, in principle, it should function most efficiently when reconstituted into a fully fluid lipid bilayer, but in many model membranes, lateral fluidity of the membrane and protein is sacrificed for electrochemical addressability because of the need for an electroactive surface. Here, we reported a biomolecular photoactive device based on light-activated proton pump, bR, reconstituted into highly fluidic microcavity-supported lipid bilayers (MSLBs) on functionalized gold and polydimethylsiloxane cavity array substrates. The integrity of reconstituted bR at the MSLBs along with the lipid bilayer formation was evaluated by fluorescence lifetime correlation spectroscopy, yielding a protein lateral diffusion coefficient that was dependent on the bR concentration and consistent with the Saffman-Delbrück model. The photoelectrical properties of bR-MSLBs were evaluated from the photocurrent signal generated by bR under continuous and transient light illumination. The optimal conditions for a self-sustaining photoelectrical switch were determined in terms of protein concentration, pH, and light switch frequency of activation. Overall, a significant increase in the transient current was observed for lipid bilayers containing approximately 0.3 mol % bR with a measured photo-current of 250 nA/cm2. These results demonstrate that the platforms provide an appropriate lipid environment to support the proton pump, enabling its efficient operation. The bR-reconstituted MSLB model serves both as a platform to study the protein in a highly addressable biomimetic environment and as a demonstration of reconstitution of seven-helix receptors into MSLBs, opening the prospect of reconstitution of related membrane proteins including G-protein-coupled receptors on these versatile biomimetic substrates.
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Affiliation(s)
- Guilherme
B. Berselli
- School of Chemical Sciences, National
Centre for Sensor Research, Dublin City
University, Dublin D09 FW22, Ireland
| | - Aurélien
V. Gimenez
- School of Chemical Sciences, National
Centre for Sensor Research, Dublin City
University, Dublin D09 FW22, Ireland
| | - Alexandra O’Connor
- School of Chemical Sciences, National
Centre for Sensor Research, Dublin City
University, Dublin D09 FW22, Ireland
| | - Tia E. Keyes
- School of Chemical Sciences, National
Centre for Sensor Research, Dublin City
University, Dublin D09 FW22, Ireland
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9
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Charge Transport by Light-Activated Rhodopsins Determined by Electrophysiological Recordings. Methods Mol Biol 2020. [PMID: 32865739 DOI: 10.1007/978-1-0716-0830-2_5] [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
Electrophysiological experiments are required to determine the ion transport properties of light-activated currents from microbial rhodopsin expressing cells. The recordings set the quantitative basis for correlation with spectroscopic data and for understanding of channel gating, ion transport vectoriality, or ion selectivity. This chapter focuses on voltage-clamp recordings of channelrhodopsin-2-expressing cells, and it will describe different illumination protocols that reveal the kinetic properties of gating. While the opening and closing reaction is determined from a single turnover upon a short laser flash, desensitization of the light-gated currents is studied under continuous illumination. Recovery from the desensitized state is probed after prolonged illumination with a subsequent light activation upon different dark intervals. Compiling the experimental data will define a minimum number of states in kinetic schemes used to describe the light-gated currents in channelrhodopsins, and emphasis will be given on how to correlate the results with the different time-resolved spectroscopic experiments.
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10
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Mech-Dorosz A, Bajraktari N, Hélix-Nielsen C, Emnéus J, Heiskanen A. Stationary photocurrent generation from bacteriorhodopsin-loaded lipo-polymersomes in polyelectrolyte multilayer assembly on polyethersulfone membrane. Anal Bioanal Chem 2020; 412:6307-6318. [PMID: 32166446 DOI: 10.1007/s00216-020-02533-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Revised: 02/12/2020] [Accepted: 02/17/2020] [Indexed: 11/24/2022]
Abstract
Vesicles constructed of either synthetic polymers alone (polymersomes) or a combination of polymers and lipids (lipo-polymersomes) demonstrate excellent long-term stability and ability to integrate membrane proteins. Applications using lipo-polymersomes with integrated membrane proteins require suitable supports to maintain protein functionality. Using lipo-polymersomes loaded with the light-driven proton pump bacteriorhodopsin (BR), we demonstrate here how the photocurrent is influenced by a chosen support. In our study, we deposited BR-loaded lipo-polymersomes in a cross-linked polyelectrolyte multilayer assembly either directly physisorbed on gold electrode microchips or cross-linked on an intermediary polyethersulfone (PES) membrane covalently grafted using a hydrogel cushion. In both cases, electrochemical impedance spectroscopic characterization demonstrated successful polyelectrolyte assembly with BR-loaded lipo-polymersomes. Light-induced proton pumping by BR-loaded lipo-polymersomes in the different support constructs was characterized by amperometric recording of the generated photocurrent. Application of the hydrogel/PES membrane support together with the polyelectrolyte assembly decreased the transient current response upon light activation of BR, while enhancing the generated stationary current to over 700 nA/cm2. On the other hand, the current response from BR-loaded lipo-polymersomes in a polyelectrolyte assembly without the hydrogel/PES membrane support was primarily a transient peak combined with a low-nanoampere-level stationary photocurrent. Hence, the obtained results demonstrated that by using a hydrogel/PES support it was feasible to monitor continuously light-induced proton flux in biomimetic applications of lipo-polymersomes. Graphical abstract.
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Affiliation(s)
- Agnieszka Mech-Dorosz
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Produktionstorvet, Building 423, 2800, Kgs. Lyngby, Denmark
- Novo Nordisk A/S, Brennum Park 24 K, 3400, Hillerød, Denmark
| | - Niada Bajraktari
- Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet, Building 115, 2800, Kgs. Lyngby, Denmark
- Aquaporin A/S, Nymøllevej 78, 2800, Kgs. Lyngby, Denmark
| | - Claus Hélix-Nielsen
- Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet, Building 115, 2800, Kgs. Lyngby, Denmark
- Aquaporin A/S, Nymøllevej 78, 2800, Kgs. Lyngby, Denmark
| | - Jenny Emnéus
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Produktionstorvet, Building 423, 2800, Kgs. Lyngby, Denmark
| | - Arto Heiskanen
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Produktionstorvet, Building 423, 2800, Kgs. Lyngby, Denmark.
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Abstract
Recently, two groups of rhodopsin genes were identified in large double-stranded DNA viruses. The structure and function of viral rhodopsins are unknown. We present functional characterization and high-resolution structure of an Organic Lake Phycodnavirus rhodopsin II (OLPVRII) of group 2. It forms a pentamer, with a symmetrical, bottle-like central channel with the narrow vestibule in the cytoplasmic part covered by a ring of 5 arginines, whereas 5 phenylalanines form a hydrophobic barrier in its exit. The proton donor E42 is placed in the helix B. The structure is unique among the known rhodopsins. Structural and functional data and molecular dynamics suggest that OLPVRII might be a light-gated pentameric ion channel analogous to pentameric ligand-gated ion channels, however, future patch clamp experiments should prove this directly. The data shed light on a fundamentally distinct branch of rhodopsins and may contribute to the understanding of virus-host interactions in ecologically important marine protists.
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From Gene to Function: Cell-Free Electrophysiological and Optical Analysis of Ion Pumps in Nanodiscs. Biophys J 2017; 113:1331-1341. [PMID: 28450130 DOI: 10.1016/j.bpj.2017.03.026] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 03/14/2017] [Accepted: 03/27/2017] [Indexed: 12/15/2022] Open
Abstract
Nanodiscs that hold a lipid bilayer surrounded by a boundary of scaffold proteins have emerged as a powerful tool for membrane protein solubilization and analysis. By combining nanodiscs and cell-free expression technologies, even completely detergent-free membrane protein characterization protocols can be designed. Nanodiscs are compatible with various techniques, and due to their bilayer environment and increased stability, they are often superior to detergent micelles or liposomes for membrane protein solubilization. However, transport assays in nanodiscs have not been conducted so far, due to limitations of the two-dimensional nature of nanodisc membranes that offers no compartmentalization. Here, we study Krokinobacter eikastus rhodopsin-2 (KR2), a microbial light-driven sodium or proton pump, with noncovalent mass-spectrometric, electrophysiological, and flash photolysis measurements after its cotranslational insertion into nanodiscs. We demonstrate the feasibility of adsorbing nanodiscs containing KR2 to an artificial bilayer. This allows us to record light-induced capacitive currents that reflect KR2's ion transport activity. The solid-supported membrane assay with nanodisc samples provides reliable control over the ionic condition and information of the relative ion activity of this promiscuous pump. Our strategy is complemented with flash photolysis data, where the lifetimes of different photointermediates were determined at different ionic conditions. The advantage of using identical samples to three complementary approaches allows for a comprehensive comparability. The cell-free synthesis in combination with nanodiscs provides a defined hydrophobic lipid environment minimizing the detergent dependence often seen in assays with membrane proteins. KR2 is a promising tool for optogenetics, thus directed engineering to modify ion selectivity can be highly beneficial. Our approach, using the fast generation of functional ion pumps incorporated into nanodiscs and their subsequent analysis by several biophysical techniques, can serve as a versatile screening and engineering platform. This may open new avenues for the study of ion pumps and similar electrogenic targets.
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13
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Light-Patterned Current Generation in a Droplet Bilayer Array. Sci Rep 2017; 7:46585. [PMID: 28417964 PMCID: PMC5394532 DOI: 10.1038/srep46585] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 03/17/2017] [Indexed: 11/08/2022] Open
Abstract
We have created a 4 × 4 droplet bilayer array comprising light-activatable aqueous droplet bio-pixels. Aqueous droplets containing bacteriorhodopsin (bR), a light-driven proton pump, were arranged on a common hydrogel surface in lipid-containing oil. A separate lipid bilayer formed at the interface between each droplet and the hydrogel; each bilayer then incorporated bR. Electrodes in each droplet simultaneously measured the light-driven proton-pumping activities of each bio-pixel. The 4 × 4 array derived by this bottom-up synthetic biology approach can detect grey-scale images and patterns of light moving across the device, which are transduced as electrical current generated in each bio-pixel. We propose that synthetic biological light-activatable arrays, produced with soft materials, might be interfaced with living tissues to stimulate neuronal pathways.
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Albarracín VH, Kraiselburd I, Bamann C, Wood PG, Bamberg E, Farias ME, Gärtner W. Functional Green-Tuned Proteorhodopsin from Modern Stromatolites. PLoS One 2016; 11:e0154962. [PMID: 27187791 PMCID: PMC4871484 DOI: 10.1371/journal.pone.0154962] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 04/21/2016] [Indexed: 11/18/2022] Open
Abstract
The sequenced genome of the poly-extremophile Exiguobacterium sp. S17, isolated from modern stromatolites at Laguna Socompa (3,570 m), a High-Altitude Andean Lake (HAAL) in Argentinean Puna revealed a putative proteorhodopsin-encoding gene. The HAAL area is exposed to the highest UV irradiation on Earth, making the microbial community living in the stromatolites test cases for survival strategies under extreme conditions. The heterologous expressed protein E17R from Exiguobacterium (248 amino acids, 85% sequence identity to its ortholog ESR from E. sibiricum) was assembled with retinal displaying an absorbance maximum at 524 nm, which makes it a member of the green-absorbing PR-subfamily. Titration down to low pH values (eventually causing partial protein denaturation) indicated a pK value between two and three. Global fitting of data from laser flash-induced absorption changes gave evidence for an early red-shifted intermediate (its formation being below the experimental resolution) that decayed (τ1 = 3.5 μs) into another red-shifted intermediate. This species decayed in a two-step process (τ2 = 84 μs, τ3 = 11 ms), to which the initial state of E17-PR was reformed with a kinetics of 2 ms. Proton transport capability of the HAAL protein was determined by BLM measurements. Additional blue light irradiation reduced the proton current, clearly identifying a blue light absorbing, M-like intermediate. The apparent absence of this intermediate is explained by closely matching formation and decay kinetics.
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Affiliation(s)
- Virginia Helena Albarracín
- Planta Piloto de Procesos Industriales y Microbiológicos (PROIMI), CCT, CONICET. Av. Belgrano y Pasaje Caseros. 4000- S. M. de Tucumán, Argentina
- Facultad de Ciencias Naturales e Instituto Miguel Lillo, Universidad Nacional de Tucumán, 4000, S. M. de Tucumán, Argentina
- * E-mail: (VHA); (WG)
| | - Ivana Kraiselburd
- Instituto de Biología Molecular y Celular de Rosario (IBR - CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas (FBIOYF - UNR), Suipacha 590, 2000, Rosario, Santa Fe, Argentina
| | - Christian Bamann
- Max-Planck-Institute for Biophysics, Max-von-Laue-Straße 3, D-60438 Frankfurt am Main, Germany
| | - Phillip G. Wood
- Max-Planck-Institute for Biophysics, Max-von-Laue-Straße 3, D-60438 Frankfurt am Main, Germany
| | - Ernst Bamberg
- Max-Planck-Institute for Biophysics, Max-von-Laue-Straße 3, D-60438 Frankfurt am Main, Germany
| | - María Eugenia Farias
- Max-Planck-Institute for Biophysics, Max-von-Laue-Straße 3, D-60438 Frankfurt am Main, Germany
| | - Wolfgang Gärtner
- Max-Planck-Institute for Chemical Energy Conversion, Stiftstrasse 34–36, D-45470 Mülheim, Germany
- * E-mail: (VHA); (WG)
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15
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Hybrid integrated biological-solid-state system powered with adenosine triphosphate. Nat Commun 2015; 6:10070. [PMID: 26638983 PMCID: PMC4686768 DOI: 10.1038/ncomms10070] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 10/27/2015] [Indexed: 11/17/2022] Open
Abstract
There is enormous potential in combining the capabilities of the biological and the solid state to create hybrid engineered systems. While there have been recent efforts to harness power from naturally occurring potentials in living systems in plants and animals to power complementary metal-oxide-semiconductor integrated circuits, here we report the first successful effort to isolate the energetics of an electrogenic ion pump in an engineered in vitro environment to power such an artificial system. An integrated circuit is powered by adenosine triphosphate through the action of Na+/K+ adenosine triphosphatases in an integrated in vitro lipid bilayer membrane. The ion pumps (active in the membrane at numbers exceeding 2 × 106 mm−2) are able to sustain a short-circuit current of 32.6 pA mm−2 and an open-circuit voltage of 78 mV, providing for a maximum power transfer of 1.27 pW mm−2 from a single bilayer. Two series-stacked bilayers provide a voltage sufficient to operate an integrated circuit with a conversion efficiency of chemical to electrical energy of 14.9%. There is enormous potential in combining the capabilities of the biological and the solid-state to create hybrid engineered systems. Here, the authors develop a technique to incorporate and activate ATPases in in vitro membranes to produce energy-harvestable currents to power an integrated circuit.
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16
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Rao S, Guo Z, Liang D, Chen D, Li Y, Xiang Y. 3D proton transfer augments bio-photocurrent generation. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2015; 27:2668-2673. [PMID: 25786358 DOI: 10.1002/adma.201405737] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 02/14/2015] [Indexed: 06/04/2023]
Abstract
An enhancement of the photocurrent is achieved in a biohybrid nanocomposite consisting of nanovesicle reconstituted proteorhodopsin and potassium phosphotungstate nanoparticles. With the observation of an accelerated protein photocycle and elevated proton conductivity, this improvement of the photo-electric performance is attributed to the construction of a 3D proton-transfer framework.
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Affiliation(s)
- Siyuan Rao
- Beijing Key Laboratory of Bio-inspired Energy Materials and Devices, School of Chemistry and Environment, Beihang University, Beijing, 100191, PR China
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17
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Gushchin I, Shevchenko V, Polovinkin V, Kovalev K, Alekseev A, Round E, Borshchevskiy V, Balandin T, Popov A, Gensch T, Fahlke C, Bamann C, Willbold D, Büldt G, Bamberg E, Gordeliy V. Crystal structure of a light-driven sodium pump. Nat Struct Mol Biol 2015; 22:390-5. [PMID: 25849142 DOI: 10.1038/nsmb.3002] [Citation(s) in RCA: 131] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 03/09/2015] [Indexed: 11/09/2022]
Abstract
Recently, the first known light-driven sodium pumps, from the microbial rhodopsin family, were discovered. We have solved the structure of one of them, Krokinobacter eikastus rhodopsin 2 (KR2), in the monomeric blue state and in two pentameric red states, at resolutions of 1.45 Å and 2.2 and 2.8 Å, respectively. The structures reveal the ion-translocation pathway and show that the sodium ion is bound outside the protein at the oligomerization interface, that the ion-release cavity is capped by a unique N-terminal α-helix and that the ion-uptake cavity is unexpectedly large and open to the surface. Obstruction of the cavity with the mutation G263F imparts KR2 with the ability to pump potassium. These results pave the way for the understanding and rational design of cation pumps with new specific properties valuable for optogenetics.
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Affiliation(s)
- Ivan Gushchin
- 1] Institut de Biologie Structurale, Université Grenoble Alpes, Grenoble, France. [2] Institut de Biologie Structurale, Centre National de la Recherche Scientifique, Grenoble, France. [3] Institut de Biologie Structurale, Commissariat à l'Énergie Atomique (CEA), Grenoble, France. [4] Laboratory for Advanced Studies of Membrane Proteins, Moscow Institute of Physics and Technology, Dolgoprudniy, Russia. [5] Institute of Complex Systems (ICS), ICS-6, Structural Biochemistry, Research Center Jülich, Jülich, Germany
| | - Vitaly Shevchenko
- 1] Laboratory for Advanced Studies of Membrane Proteins, Moscow Institute of Physics and Technology, Dolgoprudniy, Russia. [2] Institute of Complex Systems (ICS), ICS-6, Structural Biochemistry, Research Center Jülich, Jülich, Germany. [3] Institute of Crystallography, University of Aachen (RWTH), Aachen, Germany
| | - Vitaly Polovinkin
- 1] Institut de Biologie Structurale, Université Grenoble Alpes, Grenoble, France. [2] Institut de Biologie Structurale, Centre National de la Recherche Scientifique, Grenoble, France. [3] Institut de Biologie Structurale, Commissariat à l'Énergie Atomique (CEA), Grenoble, France. [4] Laboratory for Advanced Studies of Membrane Proteins, Moscow Institute of Physics and Technology, Dolgoprudniy, Russia. [5] Institute of Complex Systems (ICS), ICS-6, Structural Biochemistry, Research Center Jülich, Jülich, Germany
| | - Kirill Kovalev
- 1] Laboratory for Advanced Studies of Membrane Proteins, Moscow Institute of Physics and Technology, Dolgoprudniy, Russia. [2] Institute of Complex Systems (ICS), ICS-6, Structural Biochemistry, Research Center Jülich, Jülich, Germany
| | - Alexey Alekseev
- 1] Laboratory for Advanced Studies of Membrane Proteins, Moscow Institute of Physics and Technology, Dolgoprudniy, Russia. [2] Institute of Complex Systems (ICS), ICS-6, Structural Biochemistry, Research Center Jülich, Jülich, Germany
| | - Ekaterina Round
- Institute of Complex Systems (ICS), ICS-6, Structural Biochemistry, Research Center Jülich, Jülich, Germany
| | - Valentin Borshchevskiy
- 1] Laboratory for Advanced Studies of Membrane Proteins, Moscow Institute of Physics and Technology, Dolgoprudniy, Russia. [2] Institute of Complex Systems (ICS), ICS-6, Structural Biochemistry, Research Center Jülich, Jülich, Germany
| | - Taras Balandin
- Institute of Complex Systems (ICS), ICS-6, Structural Biochemistry, Research Center Jülich, Jülich, Germany
| | | | - Thomas Gensch
- ICS, ICS-4, Cellular Biophysics, Research Center Jülich, Jülich, Germany
| | - Christoph Fahlke
- ICS, ICS-4, Cellular Biophysics, Research Center Jülich, Jülich, Germany
| | | | - Dieter Willbold
- 1] Institute of Complex Systems (ICS), ICS-6, Structural Biochemistry, Research Center Jülich, Jülich, Germany. [2] Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Georg Büldt
- 1] Laboratory for Advanced Studies of Membrane Proteins, Moscow Institute of Physics and Technology, Dolgoprudniy, Russia. [2] ICS, ICS-5, Molecular Biophysics, Research Center Jülich, Jülich, Germany
| | - Ernst Bamberg
- Max Planck Institute of Biophysics, Frankfurt am Main, Germany
| | - Valentin Gordeliy
- 1] Institut de Biologie Structurale, Université Grenoble Alpes, Grenoble, France. [2] Institut de Biologie Structurale, Centre National de la Recherche Scientifique, Grenoble, France. [3] Institut de Biologie Structurale, Commissariat à l'Énergie Atomique (CEA), Grenoble, France. [4] Laboratory for Advanced Studies of Membrane Proteins, Moscow Institute of Physics and Technology, Dolgoprudniy, Russia. [5] Institute of Complex Systems (ICS), ICS-6, Structural Biochemistry, Research Center Jülich, Jülich, Germany
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Rao S, Lu S, Guo Z, Li Y, Chen D, Xiang Y. A light-powered bio-capacitor with nanochannel modulation. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2014; 26:5846-5850. [PMID: 25043512 DOI: 10.1002/adma.201401321] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 05/19/2014] [Indexed: 06/03/2023]
Abstract
An artificial bio-capacitor system is established, consisting of the proton-pump protein proteorhodopsin and a modified alumina nanochannel, inspired by the capacitor-like behavior of plasma membranes realized through the cooperation of ion-pump and ion-channel proteins. Capacitor-like features of this simplified system are realized and identified, and the photocurrent duration time can be modulated by nanochannel modification to obtain favorable square-wave currents.
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Affiliation(s)
- Siyuan Rao
- Beijing Key Laboratory of Bio-inspired Energy Materials and Devices, School of Chemistry and Environment, Beihang University, Beijing, 100191, P. R. China
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19
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Moltke S, Alexiev U, Heyn MP. Kinetics of Light-Induced Intramolecular Charge Transfer and Proton Release in Bacteriorhodopsin. Isr J Chem 2013. [DOI: 10.1002/ijch.199500039] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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20
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Zaitsev SY, Solovyeva DO, Nabiev I. Thin films and assemblies of photosensitive membrane proteins and colloidal nanocrystals for engineering of hybrid materials with advanced properties. Adv Colloid Interface Sci 2012; 183-184:14-29. [PMID: 22906866 DOI: 10.1016/j.cis.2012.07.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2012] [Revised: 07/15/2012] [Accepted: 07/24/2012] [Indexed: 11/16/2022]
Abstract
The development and study of nano-bio hybrid materials engineered from membrane proteins (the key functional elements of various biomembranes) and nanoheterostructures (inorganic colloidal nanoparticles, transparent electrodes, and films) is a rapidly growing field at the interface of materials and life sciences. The mainspring of the development of bioinspired materials and devices is the fact that biological evolution has solved many problems similar to those that humans are attempting to solve in the field of light-harvesting and energy-transferring inorganic compounds. Along this way, bioelectronics and biophotonics have shown considerable promise. A number of proteins have been explored in terms of bioelectronic device applications, but bacteriorhodopsin (bR, a photosensitive membrane protein from purple membranes of the bacterium Halobacterium salinarum) and bacterial photosynthetic reaction centres have received the most attention. The energy harvesting in plants has a maximum efficiency of 5%, whereas bR, in the absence of a specific light-harvesting system, allows bacteria to utilize only 0.1-0.5% of the solar light. Recent nano-bioengineering approaches employing colloidal semiconductor and metal nanoparticles conjugated with biosystems permit the enhancement of the light-harvesting capacity of photosensitive proteins, thus providing a strong impetus to protein-based device optimisation. Fabrication of ultrathin and highly oriented films from biological membranes and photosensitive proteins is the key task for prospective bioelectronic and biophotonic applications. In this review, the main advances in techniques of preparation of such films are analyzed. Comparison of the techniques for obtaining thin films leads to the conclusion that the homogeneity and orientation of biomembrane fragments or proteins in these films depend on the method of their fabrication and increase in the following order: electrophoretic sedimentation < Langmuir-Blodgett and Langmuir-Schaefer methods < self-assembly and layer-by-layer methods. The key advances in the techniques of preparation of the assemblies or complexes of colloidal nanocrystals with bR, purple membranes, or photosynthetic reaction centres are also reviewed. Approaches to the fabrication of the prototype photosensitive nano-bio hybrid materials with advanced photovoltaic, energy transfer, and optical switching properties and future prospects in this field are analyzed in the concluding part of the review.
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Affiliation(s)
- Sergei Yu Zaitsev
- Laboratory of Nano-Bioengineering, Moscow Engineering Physics Institute, 31 Kashirskoe sh., 115409 Moscow, Russian Federation.
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21
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Tian Y, Jiang L. Biomimetic photoelectric conversion systems based on artificial membranes. Sci China Chem 2011. [DOI: 10.1007/s11426-011-4229-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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22
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Abstract
Since its discovery, the light-gated cation channel Channelrhodopsin-2 (ChR2) has proven to be a long-sought tool for the noninvasive, light-activated control of neural cells in culture and in living animals. Although ChR2 is widely used in neurobiological applications, little is known about its molecular mechanism. In this work, the unitary conductance of ChR2 was determined for different cations, for example 40 fS at 200 mM NaCl and -60 mV, using noise analysis. The kinetics of the ion channel obtained by noise analysis is in excellent agreement with the photocurrent kinetics obtained by voltage-clamp and time-resolved spectroscopy. The inward rectification of the channel could be explained by the single channel parameters. ChR2 represents an ion channel with a 7 transmembrane helix motif, even though the sequence homology of its essential amino acids to those of the light-driven H(+) pump bacteriorhodopsin (bR) is high. Here, we also show that when ChR2 is expressed in electrofused giant HEK293 cells or reconstituted on planar lipid membranes, it can indeed act as an outwardly driven H(+) pump, demonstrating that ChR2 is bifunctional, and in-line with other microbial rhodopsins, a H(+) pump but with a leak that shows ion channel properties.
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23
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Abstract
Electrogenic events due to the activity of wild-type lactose permease from Escherichia coli (LacY) were investigated with proteoliposomes containing purified LacY adsorbed on a solid-supported membrane electrode. Downhill sugar/H(+) symport into the proteoliposomes generates transient currents. Studies at different lipid-to-protein ratios and at different pH values, as well as inactivation by N-ethylmaleimide, show that the currents are due specifically to the activity of LacY. From analysis of the currents under different conditions and comparison with biochemical data, it is suggested that the predominant electrogenic event in downhill sugar/H(+) symport is H(+) release. In contrast, LacY mutants Glu-325-->Ala and Cys-154-->Gly, which bind ligand normally, but are severely defective with respect to lactose/H(+) symport, exhibit only a small electrogenic event on addition of LacY-specific substrates, representing 6% of the total charge displacement of the wild-type. This activity is due either to substrate binding per se or to a conformational transition after substrate binding, and is not due to sugar/H(+) symport. We propose that turnover of LacY involves at least 2 electrogenic reactions: (i) a minor electrogenic step that occurs on sugar binding and is due to a conformational transition in LacY; and (ii) a major electrogenic step probably due to cytoplasmic release of H(+) during downhill sugar/H(+) symport, which is the limiting step for this mode of transport.
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Tóth-Boconádi R, Dér A, Fábián L, Taneva SG, Keszthelyi L. Excitation of the M Intermediates of Bacteriorhodopsin. Photochem Photobiol 2009; 85:609-13. [DOI: 10.1111/j.1751-1097.2008.00521.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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25
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Schulz P, Garcia-Celma JJ, Fendler K. SSM-based electrophysiology. Methods 2008; 46:97-103. [PMID: 18675360 DOI: 10.1016/j.ymeth.2008.07.002] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2008] [Revised: 06/12/2008] [Accepted: 07/02/2008] [Indexed: 10/21/2022] Open
Abstract
An assay technique for the electrical characterization of electrogenic transport proteins on solid supported membranes is presented. Membrane vesicles, proteoliposomes or membrane fragments containing the transporter are adsorbed to the solid supported membrane and are activated by providing a substrate or a ligand via a rapid solution exchange. This technique opens up new possibilities where conventional electrophysiology fails like transporters or ion channels from bacteria and from intracellular compartments. Its rugged design and potential for automation make it suitable for drug screening.
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Affiliation(s)
- Patrick Schulz
- Department of Biophysical Chemistry, Max Planck Institute of Biophysics, Max von Laue Str. 3, D-60438 Frankfurt/Main, Germany
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27
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Chapter 3 Pore-Suspending Membranes on Highly Ordered Porous Alumina and Porous Silicon Substrates: Preparation, Characterization, and Application. ACTA ACUST UNITED AC 2008. [DOI: 10.1016/s1554-4516(08)00003-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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28
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Bartolommei G, Tadini-Buoninsegni F, Moncelli MR, Guidelli R. Electrogenic steps of the SR Ca-ATPase enzymatic cycle and the effect of curcumin. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1778:405-13. [PMID: 18005661 DOI: 10.1016/j.bbamem.2007.10.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2007] [Revised: 10/10/2007] [Accepted: 10/17/2007] [Indexed: 11/18/2022]
Abstract
Sarcoplasmic reticulum (SR) vesicles were adsorbed on an octadecanethiol/phosphatidylcholine mixed bilayer anchored to a gold electrode, and the Ca-ATPase contained in the vesicles was activated by ATP concentration jumps in the presence of calcium ions. The resulting capacitive current transients are compared with those calculated on the basis of the enzymatic cycle of the calcium pump. This comparison provides information on the kinetics of the E(2)-E(1) conformational change and on its pH dependence. The alteration in the current transients following ATP concentration jumps in the presence of curcumin is examined. In particular, curcumin decreases the rate of slippage of the Ca-ATPase, and at concentrations above 10 microM reduces calcium transport by this pump.
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Affiliation(s)
- Gianluca Bartolommei
- Department of Chemistry, University of Florence, via della Lastruccia 3, 50019 Sesto Fiorentino (FI), Italy
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Tittor J, Oesterhelt D, Bamberg E. Bacteriorhodopsin mutants D85N, D85T and D85,96N as proton pumps. Biophys Chem 2007; 56:153-7. [PMID: 17023320 DOI: 10.1016/0301-4622(95)00027-u] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Proton translocation in the BR mutants D85N, D85T and D85,96N was studied by attachment of purple membranes to planar lipid bilayers. Pump currents in these mutants were measured via capacitive coupling and by use of the appropriate ionophores. All mutants have a reduced pK of their Schiff bases around 8-8.5 in common. At physiological pH, a mixture of chromophores absorbing at 410 nm (deprotonated form) and around 600 nm (protonated form) coexists. Excitation with continuous blue light induces in all three mutants an outwardly directed stationary pump current. These currents are enhanced upon addition of azide in D85N and D85,96N by a factor of 50, but no azide enhancement is observed in D85T. Yellow light alone induces transient inwardly directed currents in the mutants but additional blue light leads to a stationary current with the same direction. All the observed currents are carried by protons, so that the consecutive absorption of a yellow and a blue photon leads to inverted stationary photocurrents by the mutants, as observed with halorhodopsin (HR). A mechanistic model describing the inversion of proton pumping is discussed by the cis-trans, trans-cis isomerization of the retinal and the different proton accessibility of the Schiff base from the extracellular or the cytoplasmic side of the membrane.
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Affiliation(s)
- J Tittor
- Max-Planck-Institut für Biochemie, D-82152 Martinsried, Germany
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30
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Kalmbach R, Chizhov I, Schumacher MC, Friedrich T, Bamberg E, Engelhard M. Functional cell-free synthesis of a seven helix membrane protein: in situ insertion of bacteriorhodopsin into liposomes. J Mol Biol 2007; 371:639-48. [PMID: 17586523 DOI: 10.1016/j.jmb.2007.05.087] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2006] [Revised: 05/15/2007] [Accepted: 05/30/2007] [Indexed: 11/24/2022]
Abstract
The expression of membrane proteins for functional and structural studies or medicinal applications is still not very well established. Membrane-spanning proteins that mediate the information flow of the extracellular side with the interior of the cell are prime targets for drug development methods that would allow screening techniques or high throughput formats are of particular interest. Here we describe a systematic approach to the liposome-assisted cell-free synthesis of functional membrane proteins. We demonstrate the synthesis of bacteriorhodopsin (bR(cf)) in presence of small unilamellar liposomes. The yield of bR(cf) per volume cell culture is comparable to that of bacteriorhodopsin in its native host. The functional analysis of bR(cf) was performed directly using the cell-free reaction mixture. Photocycle measurements reveal kinetic data similar to that determined for bR in Halobacterium salinarum cell-envelope vesicles. The liposomes can be attached directly to black lipid membranes (BLM), which allows measuring light activated photocurrents in situ. The results reveal a functional proton pump with properties identical to those established for the native protein.
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Affiliation(s)
- Rolf Kalmbach
- Max-Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227 Dortmund, Germany
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31
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Tadini-Buoninsegni F, Bartolommei G, Moncelli MR, Guidelli R, Inesi G. Pre-steady state electrogenic events of Ca2+/H+ exchange and transport by the Ca2+-ATPase. J Biol Chem 2006; 281:37720-7. [PMID: 17032645 DOI: 10.1074/jbc.m606040200] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Native or recombinant SERCA (sarco(endo)plasmic reticulum Ca(2+) ATPase) was adsorbed on a solid supported membrane and then activated with Ca(2+) and ATP concentration jumps through rapid solution exchange. The resulting electrogenic events were recorded as electrical currents flowing along the external circuit. Current transients were observed following Ca(2+) jumps in the absence of ATP and following ATP jumps in the presence of Ca(2+). The related charge movements are attributed to Ca(2+) reaching its binding sites in the ground state of the enzyme (E(1)) and to its vectorial release from the enzyme phosphorylated by ATP (E(2)P). The Ca(2+) concentration and pH dependence as well as the time frames of the observed current transients are consistent with equilibrium and pre-steady state biochemical measurements of sequential steps within a single enzymatic cycle. Numerical integration of the current transients recorded at various pH values reveal partial charge compensation by H(+) in exchange for Ca(2+) at acidic (but not at alkaline) pH. Most interestingly, charge movements induced by Ca(2+) and ATP vary over different pH ranges, as the protonation probability of residues involved in Ca(2+)/H(+) exchange is lower in the E(1) than in the E(2)P state. Our single cycle measurements demonstrate that this difference contributes directly to the reduction of Ca(2+) affinity produced by ATP utilization and results in the countertransport of two Ca(2+) and two H(+) within each ATPase cycle at pH 7.0. The effects of site-directed mutations indicate that Glu-771 and Asp-800, within the Ca(2+) binding domain, are involved in the observed Ca(2+)/H(+) exchange.
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32
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Bartolommei G, Tadini-Buoninsegni F, Hua S, Moncelli MR, Inesi G, Guidelli R. Clotrimazole Inhibits the Ca2+-ATPase (SERCA) by Interfering with Ca2+ Binding and Favoring the E2 Conformation. J Biol Chem 2006; 281:9547-51. [PMID: 16452481 DOI: 10.1074/jbc.m510550200] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Clotrimazole (CLT) is an antimycotic imidazole derivative that is known to inhibit cytochrome P-450, ergosterol biosynthesis and proliferation of cells in culture, and to interfere with cellular Ca(2+) homeostasis. We found that CLT inhibits the Ca(2+)-ATPase of rabbit fast-twitch skeletal muscle (SERCA1), and we characterized in detail the effect of CLT on this calcium transport ATPase. We used biochemical methods for characterization of the ATPase and its partial reactions, and we also performed measurements of charge movements following adsorption of sarcoplasmic reticulum vesicles containing the ATPase onto a gold-supported biomimetic membrane. CLT inhibits Ca(2+)-ATPase and Ca(2+) transport with a K(I) of 35 mum. Ca(2+) binding in the absence of ATP and phosphoenzyme formation by the utilization of ATP in the presence of Ca(2+) are also inhibited within the same CLT concentration range. On the other hand, phosphoenzyme formation by utilization of P(i) in the absence of Ca(2+) is only minimally inhibited. It is concluded that CLT inhibits primarily Ca(2+) binding and, consequently, the Ca(2+)-dependent reactions of the SERCA cycle. It is suggested that CLT resides within the membrane-bound region of the transport ATPase, thereby interfering with binding and the conformational effects of the activating cation.
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Affiliation(s)
- Gianluca Bartolommei
- Department of Chemistry, University of Florence, 50019 Sesto Fiorentino, Florence, Italy
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33
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Koepsell H. Methodological aspects of purification and reconstitution of transport proteins from mammalian plasma membranes. Rev Physiol Biochem Pharmacol 2006; 104:65-137. [PMID: 2940665 DOI: 10.1007/bfb0031013] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Horn C, Steinem C. Photocurrents generated by bacteriorhodopsin adsorbed on nano-black lipid membranes. Biophys J 2005; 89:1046-54. [PMID: 15908580 PMCID: PMC1366590 DOI: 10.1529/biophysj.105.059550] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Purple membranes were adsorbed on freestanding lipid bilayers, termed nano-black lipid membranes (nano-BLMs), suspending the pores of porous alumina substrates with average pore diameters of 280 nm. Nano-BLMs were obtained by first coating the upper surface of the highly ordered porous alumina substrates with a thin gold layer followed by chemisorption of 1,2-dipalmitoyl-sn-glycero-3-phosphothioethanol and subsequent addition of a droplet of 1,2-diphytanoyl-sn-glycero-3-phosphocholine and octadecylamine dissolved in n-decane onto the hydrophobic submonolayer. By means of impedance spectroscopy, the quality of the nano-BLMs was verified. The electrical parameters confirm the formation of single lipid bilayers with high membrane resistances covering the porous matrix. Adsorption of purple membranes on the nano-BLMs was followed by recording the photocurrents generated by bacteriorhodopsin upon continuous light illumination. The membrane system exhibits a very high long-term stability with the advantage that not only transient but also stationary currents are recordable. By adding the proton ionophore carbonyl cyanide-m-chlorophenylhydrazone the conductivity of the nano-BLMs increases, resulting in a higher stationary current, which proves that proton conductance occurs across the nano-BLMs.
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Affiliation(s)
- Christian Horn
- Institut für Analytische Chemie, Chemo- und Biosensorik, Universität Regensburg, Germany
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35
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Zhou A, Wozniak A, Meyer-Lipp K, Nietschke M, Jung H, Fendler K. Charge translocation during cosubstrate binding in the Na+/proline transporter of E.coli. J Mol Biol 2004; 343:931-42. [PMID: 15476811 DOI: 10.1016/j.jmb.2004.09.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2004] [Revised: 09/02/2004] [Accepted: 09/02/2004] [Indexed: 10/26/2022]
Abstract
Charge translocation associated with the activity of the Na(+)/proline cotransporter PutP of Escherichia coli was analyzed for the first time. Using a rapid solution exchange technique combined with a solid-supported membrane (SSM), it was demonstrated that Na(+)and/or proline individually or together induce a displacement of charge. This was assigned to an electrogenic Na(+)and/or proline binding process at the cytoplasmic face of the enzyme with a rate constant of k>50s(-1) which preceeds the rate-limiting step. Based on the kinetic analysis of our electrical signals, the following characteristics are proposed for substrate binding in PutP. (1) Substrate binding is electrogenic not only for Na(+), but also for the uncharged cosubstrate proline. The charge displacement associated with the binding of both substrates is of comparable size and independent of the presence of the respective cosubstrate. (2) Both substrates can bind individually to the transporter. Under physiological conditions, an ordered binding mechanism prevails, while at sufficiently high concentrations, each substrate can bind in the absence of the other. (3) Both substrate binding sites interact cooperatively with each other by increasing the affinity and/or the speed of binding of the respective cosubstrate. (4) Proline binding proceeds in a two-step process: low affinity (approximately 1mM) electroneutral substrate binding followed by a nearly irreversible electrogenic conformational transition.
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Affiliation(s)
- A Zhou
- Max Planck Institut für Biophysik, Marie Curie Strasse 15, D-60439 Frankfurt/Main, Germany
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36
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Bartolommei G, Buoninsegni FT, Moncelli MR. Calcium transport by sarcoplasmic reticulum Ca-ATPase can be investigated on a solid-supported membrane. Bioelectrochemistry 2004; 63:157-60. [PMID: 15110266 DOI: 10.1016/j.bioelechem.2003.07.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2003] [Revised: 07/17/2003] [Accepted: 07/22/2003] [Indexed: 10/26/2022]
Abstract
Sarcoplasmic reticulum (SR) native vesicles incorporating Ca-ATPase are adsorbed on a solid-supported lipid membrane (SSM). Upon adsorption, the ion pumps are chemically activated by concentration jumps of ATP and the capacitive current transients generated by SR Ca-ATPase are measured under potentiostatic conditions. The Michaelis-Menten constant, K(M), for ATP is evaluated by varying the concentration of ATP in the activating solution. This preliminary result shows that ion transport by SR Ca-ATPase can be suitably investigated by a technique based on concentration jumps on an SSM.
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Affiliation(s)
- G Bartolommei
- Laboratory of Bioelectrochemistry, Chemistry Department, University of Florence, via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy
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37
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Tadini Buoninsegni F, Bartolommei G, Moncelli MR, Inesi G, Guidelli R. Time-resolved charge translocation by sarcoplasmic reticulum Ca-ATPase measured on a solid supported membrane. Biophys J 2004; 86:3671-86. [PMID: 15189864 PMCID: PMC1304269 DOI: 10.1529/biophysj.103.036608] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2003] [Accepted: 03/01/2004] [Indexed: 11/18/2022] Open
Abstract
Sarcoplasmic reticulum vesicles were adsorbed on an octadecanethiol/phosphatidylcholine mixed bilayer anchored to a gold electrode, and the Ca-ATPase contained in the vesicles was activated by ATP concentration jumps both in the absence and in the presence of K(+) ions and at different pH values. Ca(2+) concentration jumps in the absence of ATP were also carried out. The resulting capacitive current transients were analyzed together with the charge under the transients. The relaxation time constants of the current transients were interpreted on the basis of an equivalent circuit. The current transient after ATP concentration jumps and the charge after Ca(2+) concentration jumps in the absence of ATP exhibit almost the same dependence upon the Ca(2+) concentration, with a half-saturating value of approximately 1.5 microM. The pH dependence of the charge after Ca(2+) translocation demonstrates the occurrence of one H(+) per one Ca(2+) countertransport at pH 7 by direct charge-transfer measurements. The presence of K(+) decreases the magnitude of the current transients without altering their shape; this decrease is explained by K(+) binding to the cytoplasmic side of the pump in the E(1) conformation and being released to the same side during the E(1)-E(2) transition.
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38
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Tadini Buoninsegni F, Dolfi A, Guidelli R. Two Photobioelectrochemical Applications of Self-Assembled Films on Mercury. ACTA ACUST UNITED AC 2004. [DOI: 10.1135/cccc20040292] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The homogeneous, defect-free surface of a hanging mercury drop electrode was used to self-assemble films apt for the investigation of two photobioelectrochemical systems. Monolayers of straight-chain C12-C18alkane-1-thiols were anchored to a hanging mercury drop electrode and a film of chlorophyll was self-assembled on the top of them. The dependence of the photocurrents generated by illumination of the chlorophyll film with red light, on the thickness of the alkane-1-thiol monolayer and the applied potential is discussed. The photocurrents of purple membrane fragments, adsorbed on a mixed hexadecane-1-thiol/ dioleoylphosphatidylcholine bilayer self-assembled on mercury, were investigated in the presence of sodium perchlorate, chloride and acetate. The effect of the anions on the kinetics of the light-driven proton transport by bacteriorhodopsin has been determined.
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Tadini-Buoninsegni F, Nassi P, Nediani C, Dolfi A, Guidelli R. Investigation of Na(+),K(+)-ATPase on a solid supported membrane: the role of acylphosphatase on the ion transport mechanism. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1611:70-80. [PMID: 12659947 DOI: 10.1016/s0005-2736(02)00722-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Charge translocation by Na(+),K(+)-ATPase was investigated by adsorbing membrane fragments containing Na(+),K(+)-ATPase from pig kidney on a solid supported membrane (SSM). Upon adsorption, the ion pumps were activated by performing ATP concentration jumps at the surface of the SSM, and the capacitive current transients generated by Na(+),K(+)-ATPase were measured under potentiostatic conditions. To study the behavior of the ion pump under multiple turnover conditions, ATP concentration jump experiments were carried out in the presence of Na(+) and K(+) ions. Current transients induced by ATP concentration jumps were also recorded in the presence of the enzyme alpha-chymotrypsin. The effect of acylphosphatase (AcP), a cytosolic enzyme that may affect the functioning of Na(+),K(+)-ATPase by hydrolyzing its acylphosphorylated intermediate, was investigated by performing ATP concentration jumps both in the presence and in the absence of AcP. In the presence of Na(+) but not of K(+), the addition of AcP causes the charge translocated as a consequence of ATP concentration jumps to decrease by about 50% over the pH range from 6 to 7, and to increase by about 20% at pH 8. Conversely, no appreciable effect of pH upon the translocated charge is observed in the absence of AcP. The above behavior suggests that protons are involved in the AcP-catalyzed dephosphorylation of the acylphosphorylated intermediate of Na(+),K(+)-ATPase.
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40
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Friedrich T, Geibel S, Kalmbach R, Chizhov I, Ataka K, Heberle J, Engelhard M, Bamberg E. Proteorhodopsin is a light-driven proton pump with variable vectoriality. J Mol Biol 2002; 321:821-38. [PMID: 12206764 DOI: 10.1016/s0022-2836(02)00696-4] [Citation(s) in RCA: 190] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Proteorhodopsin, a homologue of archaeal bacteriorhodopsin (BR), belongs to a newly identified family of retinal proteins from marine bacteria, which could play an important role in the energy balance of the biosphere. We cloned the cDNA sequence of proteorhodopsin by chemical gene synthesis, expressed the protein in Escherichia coli cells, purified and reconstituted the protein in its functional active state. The photocycle characteristics were determined by time-resolved absorption and Fourier transform infrared (FT-IR) spectroscopy. The pH-dependence of the absorption spectrum indicates that the pK(a) of the primary acceptor of the Schiff base proton (Asp97) is 7.68. Generally, the photocycle of proteorhodopsin is similar to that of BR, although an L-like photocycle intermediate was not detectable. Whereas at pH>7 an M-like intermediate is formed upon illumination, at pH 5 no M-like intermediate could be detected. As the photocycle kinetics do not change between the acidic and alkaline state of proteorhodopsin, the only difference between these two forms is the protonation status of Asp97. This is corroborated by time-resolved FT-IR spectroscopy, which demonstrates that proton transfer from the retinal Schiff base to Asp97 is observed at alkaline pH, but the other vibrational changes are essentially pH-independent.After reconstitution into proteoliposomes, light-induced proton currents of proteorhodopsin were measured in a compound membrane system where proteoliposomes were adsorbed to planar lipid bilayers. Our results show that proteorhodopsin is a light-driven proton pump with characteristics similar to those of BR at alkaline pH. However, at acidic pH, the direction of proton pumping is inverted. Complementary experiments were carried out on proteorhodopsin expressed heterologously in Xenopus laevis oocytes under voltage clamp conditions. The following results were obtained. (1) At alkaline pH, proteorhodopsin mediates outwardly directed proton pumping like BR. (2) The direction of proton pumping can be inverted, when Asp97 is protonated. (3) The current can be inverted by changes of the polarity of the applied voltage. (4) The light intensity-dependence of the photocurrents leads to the conclusion that the alkaline form of proteorhodopsin shows efficient proton pumping after sequential excitation by two photons.
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Affiliation(s)
- Thomas Friedrich
- Max-Planck-Institute of Biophysics, Department of Biophysical Chemistry, Kennedyallee 70, D-60596 Frankfurt am Main, Germany
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41
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43
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Schmies G, Engelhard M, Wood PG, Nagel G, Bamberg E. Electrophysiological characterization of specific interactions between bacterial sensory rhodopsins and their transducers. Proc Natl Acad Sci U S A 2001; 98:1555-9. [PMID: 11171989 PMCID: PMC29295 DOI: 10.1073/pnas.98.4.1555] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The halobacterial phototaxis receptors sensory rhodopsin I and II (SRI, SRII) enable the bacteria to seek optimal light conditions for ion pumping by bacteriorhodopsin and/or halorhodopsin. The incoming signal is transferred across the plasma membrane by means of receptor-specific transducer proteins that bind tightly to their corresponding photoreceptors. To investigate the receptor/transducer interaction, advantage is taken of the observation that both SRI and SRII can function as proton pumps. SRI from Halobacterium salinarum, which triggers the positive phototaxis, the photophobic receptor SRII from Natronobacterium pharaonis (pSRII), as well as the mutant pSRII-F86D were expressed in Xenopus oocytes. Voltage-clamp studies confirm that SRI and pSRII function as light-driven, outwardly directed proton pumps with a much stronger voltage dependence than the ion pumps bacteriorhodopsin and halorhodopsin. Coexpression of SRI and pSRII-F86D with their corresponding transducers suppresses the proton transport, revealing a tight binding and specific interaction of the two proteins. These latter results may be exploited to further analyze the binding interaction of the photoreceptors with their downstream effectors.
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Affiliation(s)
- G Schmies
- Max-Planck-Institut für Molekulare Physiologie, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
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44
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Babes A, Fendler K. Na(+) transport, and the E(1)P-E(2)P conformational transition of the Na(+)/K(+)-ATPase. Biophys J 2000; 79:2557-71. [PMID: 11053130 PMCID: PMC1301138 DOI: 10.1016/s0006-3495(00)76496-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We have used admittance analysis together with the black lipid membrane technique to analyze electrogenic reactions within the Na(+) branch of the reaction cycle of the Na(+)/K(+)-ATPase. ATP release by flash photolysis of caged ATP induced changes in the admittance of the compound membrane system that are associated with partial reactions of the Na(+)/K(+)-ATPase. Frequency spectra and the Na(+) dependence of the capacitive signal are consistent with an electrogenic or electroneutral E(1)P <--> E(2)P conformational transition which is rate limiting for a faster electrogenic Na(+) dissociation reaction. We determine the relaxation rate of the rate-limiting reaction and the equilibrium constants for both reactions at pH 6.2-8.5. The relaxation rate has a maximum value at pH 7.4 (approximately 320 s(-1)), which drops to acidic (approximately 190 s(-1)) and basic (approximately 110 s(-1)) pH. The E(1)P <--> E(2)P equilibrium is approximately at a midpoint position at pH 6.2 (equilibrium constant approximately 0.8) but moves more to the E(1)P side at basic pH 8.5 (equilibrium constant approximately 0.4). The Na(+) affinity at the extracellular binding site decreases from approximately 900 mM at pH 6.2 to approximately 200 mM at pH 8.5. The results suggest that during Na(+) transport the free energy supplied by the hydrolysis of ATP is mainly used for the generation of a low-affinity extracellular Na(+) discharge site. Ionic strength and lyotropic anions both decrease the relaxation rate. However, while ionic strength does not change the position of the conformational equilibrium E(1)P <--> E(2)P, lyotropic anions shift it to E(1)P.
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Affiliation(s)
- A Babes
- Department of Physiology and Biophysics, Faculty of Biology, University of Bucharest, Bucharest, Romania
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45
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Schmies G, Lüttenberg B, Chizhov I, Engelhard M, Becker A, Bamberg E. Sensory rhodopsin II from the haloalkaliphilic natronobacterium pharaonis: light-activated proton transfer reactions. Biophys J 2000; 78:967-76. [PMID: 10653809 PMCID: PMC1300699 DOI: 10.1016/s0006-3495(00)76654-9] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
In the present work the light-activated proton transfer reactions of sensory rhodopsin II from Natronobacterium pharaonis (pSRII) and those of the channel-mutants D75N-pSRII and F86D-pSRII are investigated using flash photolysis and black lipid membrane (BLM) techniques. Whereas the photocycle of the F86D-pSRII mutant is quite similar to that of the wild-type protein, the photocycle of D75N-pSRII consists of only two intermediates. The addition of external proton donors such as azide, or in the case of F86D-pSRII, imidazole, accelerates the reprotonation of the Schiff base, but not the turnover. The electrical measurements prove that pSRII and F86D-pSRII can function as outwardly directed proton pumps, whereas the mutation in the extracellular channel (D75N-pSRII) leads to an inwardly directed transient current. The almost negligible size of the photostationary current is explained by the long-lasting photocycle of about a second. Although the M decay, but not the photocycle turnover, of pSRII and F86D-pSRII is accelerated by the addition of azide, the photostationary current is considerably increased. It is discussed that in a two-photon process a late intermediate (N- and/or O-like species) is photoconverted back to the original resting state; thereby the long photocycle is cut short, giving rise to the large increase of the photostationary current. The results presented in this work indicate that the function to generate ion gradients across membranes is a general property of archaeal rhodopsins.
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Affiliation(s)
- G Schmies
- Max-Planck-Institut für Molekulare Physiologie, D-44227 Dortmund, Germany
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46
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Kannt A, Pfitzner U, Ruitenberg M, Hellwig P, Ludwig B, Mäntele W, Fendler K, Michel H. Mutation of Arg-54 strongly influences heme composition and rate and directionality of electron transfer in Paracoccus denitrificans cytochrome c oxidase. J Biol Chem 1999; 274:37974-81. [PMID: 10608865 DOI: 10.1074/jbc.274.53.37974] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The effect of a single site mutation of Arg-54 to methionine in Paracoccus denitrificans cytochrome c oxidase was studied using a combination of optical spectroscopy, electrochemical and rapid kinetics techniques, and time-resolved measurements of electrical membrane potential. The mutation resulted in a blue-shift of the heme a alpha-band by 15 nm and partial occupation of the low-spin heme site by heme O. Additionally, there was a marked decrease in the midpoint potential of the low-spin heme, resulting in slow reduction of this heme species. A stopped-flow investigation of the reaction with ferrocytochrome c yielded a kinetic difference spectrum resembling that of heme a(3). This observation, and the absence of transient absorbance changes at the corresponding wavelength of the low-spin heme, suggests that, in the mutant enzyme, electron transfer from Cu(A) to the binuclear center may not occur via heme a but that instead direct electron transfer to the high-spin heme is the dominating process. This was supported by charge translocation measurements where Deltapsi generation was completely inhibited in the presence of KCN. Our results thus provide an example for how the interplay between protein and cofactors can modulate the functional properties of the enzyme complex.
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Affiliation(s)
- A Kannt
- Max-Planck-Institut für Biophysik, Abteilung Molekulare Membranbiologie, Heinrich-Hoffmann-Strasse 7, D-60528, Germany
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47
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Gropp T, Brustovetsky N, Klingenberg M, Müller V, Fendler K, Bamberg E. Kinetics of electrogenic transport by the ADP/ATP carrier. Biophys J 1999; 77:714-26. [PMID: 10423420 PMCID: PMC1300366 DOI: 10.1016/s0006-3495(99)76926-2] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
The electrogenic transport of ATP and ADP by the mitochondrial ADP/ATP carrier (AAC) was investigated by recording transient currents with two different techniques for performing concentration jump experiments: 1) the fast fluid injection method: AAC-containing proteoliposomes were adsorbed to a solid supported membrane (SSM), and the carrier was activated via ATP or ADP concentration jumps. 2) BLM (black lipid membrane) technique: proteoliposomes were adsorbed to a planar lipid bilayer, while the carrier was activated via the photolysis of caged ATP or caged ADP with a UV laser pulse. Two transport modes of the AAC were investigated, ATP(ex)-0(in) and ADP(ex)-0(in). Liposomes not loaded with nucleotides allowed half-cycles of the ADP/ATP exchange to be studied. Under these conditions the AAC transports ADP and ATP electrogenically. Mg(2+) inhibits the nucleotide transport, and the specific inhibitors carboxyatractylate (CAT) and bongkrekate (BKA) prevent the binding of the substrate. The evaluation of the transient currents yielded rate constants of 160 s(-1) for ATP and >/=400 s(-1) for ADP translocation. The function of the carrier is approximately symmetrical, i.e., the kinetic properties are similar in the inside-out and right-side-out orientations. The assumption from previous investigations, that the deprotonated nucleotides are exclusively transported by the AAC, is supported by further experimental evidence. In addition, caged ATP and caged ADP bind to the carrier with similar affinities as the free nucleotides. An inhibitory effect of anions (200-300 mM) was observed, which can be explained as a competitive effect at the binding site. The results are summarized in a transport model.
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Affiliation(s)
- T Gropp
- Max-Planck-Institut für Biophysik, 60596 Frankfurt, Germany
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48
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Pintschovius J, Fendler K. Charge translocation by the Na+/K+-ATPase investigated on solid supported membranes: rapid solution exchange with a new technique. Biophys J 1999; 76:814-26. [PMID: 9929483 PMCID: PMC1300083 DOI: 10.1016/s0006-3495(99)77245-0] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Adsorption of Na+/K+-ATPase containing membrane fragments from pig kidney to lipid membranes allows the detection of electrogenic events during the Na+/K+-ATPase reaction cycle with high sensitivity and time resolution. High stability preparations can be obtained using solid supported membranes (SSM) as carrier electrodes for the membrane fragments. The SSMs are prepared using an alkanethiol monolayer covalently linked to a gold surface on a glass substrate. The hydrophobic surface is covered with a lipid monolayer (SAM, self-assembled monolayer) to obtain a double layer system having electrical properties similar to those of unsupported bilayer membranes (BLM). As we have previously shown (, Biophys. J. 64:384-391), the Na+/K+-ATPase on a SSM can be activated by photolytic release of ATP from caged ATP. In this publication we show the first results of a new technique which allows rapid solution exchange at the membrane surface making use of the high mechanical stability of SSM preparations. Especially for substrates, which are not available as a caged substance-such as Na+ and K+-this technique is shown to be capable of yielding new results. The Na+/K+-ATPase was activated by rapid concentration jumps of ATP and Na+ (in the presence of ATP). A time resolution of up to 10 ms was obtained in these experiments. The aim of this paper is to present the new technique together with the first results obtained from the investigation of the Na+/K+-ATPase. A comparison with data taken from the literature shows considerable agreement with our experiments.
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Affiliation(s)
- J Pintschovius
- Max-Planck-Institut für Biophysik, D-60596 Frankfurt/Main, Germany
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49
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Kannt A, Soulimane T, Buse G, Becker A, Bamberg E, Michel H. Electrical current generation and proton pumping catalyzed by the ba3-type cytochrome c oxidase from Thermus thermophilus. FEBS Lett 1998; 434:17-22. [PMID: 9738443 DOI: 10.1016/s0014-5793(98)00942-9] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Several amino acid residues that have been shown to be essential for proton transfer in most cytochrome c oxidases are not conserved in the ba3-type cytochrome c oxidase from the thermophilic eubacterium Thermus thermophilus. So far, it has been unclear whether the Th. thermophilus ba3-type cytochrome c oxidase can nevertheless function as an electrogenic proton pump. In this study, we have combined charge translocation measurements on a lipid bilayer with two independent methods of proton pumping measurements to show that enzymatic turnover of the Th. thermophilus cytochrome c oxidase is indeed coupled to the generation of an electrocurrent and proton pumping across the membrane. In addition to a 'vectorial' consumption of 1.0 H+/e- for water formation, proton pumping with a stoichiometry of 0.4-0.5 H+/e- was observed. The implications of these findings for the mechanism of redox-coupled proton transfer in this unusual cytochrome c oxidase are discussed.
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Affiliation(s)
- A Kannt
- Max-Planck-Institut für Biophysik, Abteilung Molekulare Membranbiologie, Frankfurt/M., Germany
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50
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Ganea C, Tittor J, Bamberg E, Oesterhelt D. Chloride- and pH-dependent proton transport by BR mutant D85N. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1368:84-96. [PMID: 9459587 DOI: 10.1016/s0005-2736(97)00173-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Photocurrents from purple membrane suspensions of D85N BR mutant adsorbed to planar lipid membranes (BLM) were recorded under yellow (lambda > 515 nm), blue (360 nm < lambda < 420 nm) and white (lambda > 360 nm) light. The pH dependence of the transient and stationary currents was studied in the range from 4.5 to 10.5. The outwardly directed stationary currents in yellow and blue light indicate the presence of a proton pumping activity, dependent on the pH of the sample, in the same direction as in the wild-type. The inwardly directed currents in white light, due to an inverse proton translocation, in a two-photon process, show a pH dependence as well. The stationary currents in blue and white light are drastically increased in the presence of azide, but not in yellow light. The concentration dependence of the currents on azide indicates binding of azide to the protein. In the presence of 1 M sodium chloride, the stationary proton currents in yellow light show an increase by a factor of 25 at pH 5.5. On addition of 50 mM azide, the stationary current in yellow light decreases again, possibly by competition between azide and chloride for a common binding site. The observed transport modes are discussed in the framework of the recently published IST model for ion translocation by retinal proteins [U. Haupts et al., Biochemistry 36 (1997) 2-7].
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Affiliation(s)
- C Ganea
- Max-Planck-Institut für Biophysik, Frankfurt, Germany.
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