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Development of an automated system to measure ion channel currents using a surface-modified gold probe. Sci Rep 2021; 11:17934. [PMID: 34504175 PMCID: PMC8429628 DOI: 10.1038/s41598-021-97237-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 08/18/2021] [Indexed: 11/08/2022] Open
Abstract
Artificial lipid bilayer single-channel recording technique has been employed to determine the biophysical and pharmacological properties of various ion channels. However, its measurement efficiency is very low, as it requires two time-consuming processes: preparation of lipid bilayer membranes and incorporation of ion channels into the membranes. In order to address these problems, we previously developed a technique based on hydrophilically modified gold probes on which are immobilized ion channels that can be promptly incorporated into the bilayer membrane at the same time as the membrane is formed on the probes' hydrophilic area. Here, we improved further this technique by optimizing the gold probe and developed an automated channel current measurement system. We found that use of probes with rounded tips enhanced the efficiency of channel current measurements, and introducing a hydrophobic area on the probe surface, beside the hydrophilic one, further increased measurement efficiency by boosting membrane stability. Moreover, we developed an automated measurement system using the optimized probes; it enabled us to automatically measure channel currents and analyze the effects of a blocker on channel activity. Our study will contribute to the development of high-throughput devices to identify drug candidates affecting ion channel activity.
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Hirano M, Yamamoto D, Asakura M, Hayakawa T, Mise S, Matsumoto A, Ide T. A Lipid Bilayer Formed on a Hydrogel Bead for Single Ion Channel Recordings. MICROMACHINES 2020; 11:mi11121070. [PMID: 33271761 PMCID: PMC7759777 DOI: 10.3390/mi11121070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 11/28/2020] [Accepted: 11/29/2020] [Indexed: 02/05/2023]
Abstract
Ion channel proteins play important roles in various cell functions, making them attractive drug targets. Artificial lipid bilayer recording is a technique used to measure the ion transport activities of channel proteins with high sensitivity and accuracy. However, the measurement efficiency is low. In order to improve the efficiency, we developed a method that allows us to form bilayers on a hydrogel bead and record channel currents promptly. We tested our system by measuring the activities of various types of channels, including gramicidin, alamethicin, α-hemolysin, a voltage-dependent anion channel 1 (VDAC1), a voltage- and calcium-activated large conductance potassium channel (BK channel), and a potassium channel from Streptomyces lividans (KcsA channel). We confirmed the ability for enhanced measurement efficiency and measurement system miniaturizion.
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Affiliation(s)
- Minako Hirano
- Bio Photonics Laboratory, The Graduate School for the Creation of New Photonics Industries, Shizuoka 431-1202, Japan;
| | - Daiki Yamamoto
- Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University, Okayama 700-8530, Japan; (D.Y.); (M.A.); (T.H.)
| | - Mami Asakura
- Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University, Okayama 700-8530, Japan; (D.Y.); (M.A.); (T.H.)
| | - Tohru Hayakawa
- Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University, Okayama 700-8530, Japan; (D.Y.); (M.A.); (T.H.)
| | - Shintaro Mise
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan; (S.M.); (A.M.)
| | - Akinobu Matsumoto
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan; (S.M.); (A.M.)
| | - Toru Ide
- Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University, Okayama 700-8530, Japan; (D.Y.); (M.A.); (T.H.)
- Correspondence: ; Tel.: +81-86-251-8203
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Okuno D, Hirano M, Yokota H, Onishi Y, Ichinose J, Ide T. A Simple Method for Ion Channel Recordings Using Fine Gold Electrode. ANAL SCI 2018; 32:1353-1357. [PMID: 27941267 DOI: 10.2116/analsci.32.1353] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The artificial bilayer single-channel recording technique is commonly used to observe detailed pharmacological properties of various ion channel proteins. It permits easy control of the solution and membrane lipid composition, and is also compatible with pharmacological screening devices. However, its use is limited due to low measurement efficiency. Here, we develop a novel artificial bilayer single-channel recording technique in which bilayers are made and channels are reconstituted into the membranes by contacting a gold electrode to the lipid-solution interface. Using this technique, we measured the single-channel currents of two channel-forming peptides, gramicidin and alamethicin, and a channel-forming protein, α-hemolysin. This technique requires only one action, allowing the technique to potentially be combined with high-throughput screening devices.
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Affiliation(s)
- Daichi Okuno
- Laboratory for Cell Dynamics Observation, Quantitative Biology Center, Riken
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Okuno D, Hirano M, Yokota H, Ichinose J, Kira T, Hijiya T, Uozumi C, Yamakami M, Ide T. A gold nano-electrode for single ion channel recordings. NANOSCALE 2018; 10:4036-4040. [PMID: 29431813 DOI: 10.1039/c7nr08098k] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The artificial bilayer single channel recording technique is commonly used to observe the detailed physiological properties of various ion channel proteins. It permits easy control of the solution and membrane lipid composition, and is also compatible with pharmacological screening devices. However, its use is limited due to low measurement efficiency. Here, we developed a novel artificial bilayer single channel recording technique in which solubilized ion channel proteins immobilized on a gold nano-electrode are directly incorporated into a lipid bilayer at the same time as the bilayer is formed at the tip of it on coming in contact with an aqueous-oil interface. Using this technique, we measured the single channel currents of several types of channels including KcsA, MthK, hBK and P2X4. This technique requires only one action to simultaneously form the bilayers and reconstitute the channels into the membranes. This simplicity greatly increases the measurement efficiency and allows the technique to potentially be combined with high-throughput screening devices.
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Affiliation(s)
- Daichi Okuno
- Laboratory for Cell Dynamics Observation, Quantitative Biology Center, Riken, 6-2-3 Furue-dai Suita, Osaka 565-0874, Japan
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Affiliation(s)
- Toshihisa Osaki
- Artificial Cell
Membrane
Systems Group, Kanagawa Academy of Science and Technology, 3-2-1
Sakado, Takatsu, 213-0012 Kawasaki, Japan
- Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro, 153-8505 Tokyo, Japan
| | - Shoji Takeuchi
- Artificial Cell
Membrane
Systems Group, Kanagawa Academy of Science and Technology, 3-2-1
Sakado, Takatsu, 213-0012 Kawasaki, Japan
- Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro, 153-8505 Tokyo, Japan
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Hirano-Iwata A, Ishinari Y, Yamamoto H, Niwano M. Micro- and Nano-Technologies for Lipid Bilayer-Based Ion-Channel Functional Assays. Chem Asian J 2015; 10:1266-74. [DOI: 10.1002/asia.201403391] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Indexed: 11/06/2022]
Affiliation(s)
- Ayumi Hirano-Iwata
- CREST (Japan) Science and Technology Agency (JST); 4-1-8 Honcho Kawaguchi Saitama 332-0012 Japan
- Graduate School of Biomedical Engineering; Tohoku University; 6-6 Aoba Aramaki, Aoba-ku Sendai 980-8579 Japan
| | - Yutaka Ishinari
- CREST (Japan) Science and Technology Agency (JST); 4-1-8 Honcho Kawaguchi Saitama 332-0012 Japan
- Graduate School of Biomedical Engineering; Tohoku University; 6-6 Aoba Aramaki, Aoba-ku Sendai 980-8579 Japan
| | - Hideaki Yamamoto
- Graduate School of Biomedical Engineering; Tohoku University; 6-6 Aoba Aramaki, Aoba-ku Sendai 980-8579 Japan
- Frontier Research Institute for Interdisciplinary Sciences; Tohoku University; 6-3 Aoba Aramaki, Aoba-ku Sendai 980-8578 Japan
| | - Michio Niwano
- Graduate School of Biomedical Engineering; Tohoku University; 6-6 Aoba Aramaki, Aoba-ku Sendai 980-8579 Japan
- Laboratory for Nanoelectronics and Spintronics; Research Institute of Electrical Communication; Tohoku University; 6-6 Aoba Aramaki, Aoba-ku Sendai 980-8579 Japan
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Kitta M, Ide T, Hirano M, Tanaka H, Yanagida T, Kawai T. Direct manipulation of a single potassium channel gate with an atomic force microscope probe. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2011; 7:2379-2383. [PMID: 21656673 DOI: 10.1002/smll.201002337] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2010] [Revised: 02/21/2011] [Indexed: 05/30/2023]
Abstract
Ion channels are membrane proteins that regulate cell functions by controlling the ion permeability of cell membranes. An ion channel contains an ion-selective pore that permeates ions and a sensor that senses a specific stimulus such as ligand binding to regulate the permeability. The detailed molecular mechanisms of this regulation, or gating, are unknown. Gating is thought to occur from conformational changes in the sensor domain in response to the stimulus, which results in opening the gate to permit ion conduction. Using an atomic force microscope and artificial bilayer system, a mechanical stimulus is applied to a potassium channel, and its gating is monitored in real time. The channel-open probability increases greatly when pushing the cytoplasmic domain toward the membrane. This result shows that a mechanical stimulus at the cytoplasmic domain causes changes in the gating and is the first to show direct evidence of coupling between conformational changes in the cytoplasmic domain and channel gating. This novel technology has the potential to be a powerful tool for investigating the activation dynamics in channel proteins.
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Affiliation(s)
- Mitsunori Kitta
- The Institute of Scientific and Industrial Research (ISIR-Sanken), Osaka University, 1-8 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
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Banerjee S, Nimigean CM. Non-vesicular transfer of membrane proteins from nanoparticles to lipid bilayers. ACTA ACUST UNITED AC 2011; 137:217-23. [PMID: 21282400 PMCID: PMC3032376 DOI: 10.1085/jgp.201010558] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Discoidal lipoproteins are a novel class of nanoparticles for studying membrane proteins (MPs) in a soluble, native lipid environment, using assays that have not been traditionally applied to transmembrane proteins. Here, we report the successful delivery of an ion channel from these particles, called nanoscale apolipoprotein-bound bilayers (NABBs), to a distinct, continuous lipid bilayer that will allow both ensemble assays, made possible by the soluble NABB platform, and single-molecule assays, to be performed from the same biochemical preparation. We optimized the incorporation and verified the homogeneity of NABBs containing a prototypical potassium channel, KcsA. We also evaluated the transfer of KcsA from the NABBs to lipid bilayers using single-channel electrophysiology and found that the functional properties of the channel remained intact. NABBs containing KcsA were stable, homogeneous, and able to spontaneously deliver the channel to black lipid membranes without measurably affecting the electrical properties of the bilayer. Our results are the first to demonstrate the transfer of a MP from NABBs to a different lipid bilayer without involving vesicle fusion.
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Affiliation(s)
- Sourabh Banerjee
- Department of Anesthesiology and Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10021, USA
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