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Dong F, Lojko P, Bazzone A, Bernhard F, Borodina I. Transporter function characterization via continuous-exchange cell-free synthesis and solid supported membrane-based electrophysiology. Bioelectrochemistry 2024; 159:108732. [PMID: 38810322 DOI: 10.1016/j.bioelechem.2024.108732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 05/02/2024] [Accepted: 05/13/2024] [Indexed: 05/31/2024]
Abstract
Functional characterization of transporters is impeded by the high cost and technical challenges of current transporter assays. Thus, in this work, we developed a new characterization workflow that combines cell-free protein synthesis (CFPS) and solid supported membrane-based electrophysiology (SSME). For this, membrane protein synthesis was accomplished in a continuous exchange cell-free system (CECF) in the presence of nanodiscs. The resulting transporters expressed in nanodiscs were incorporated into proteoliposomes and assayed in the presence of different substrates using the surface electrogenic event reader. As a proof of concept, we validated this workflow to express and characterize five diverse transporters: the drug/H+-coupled antiporters EmrE and SugE, the lactose permease LacY, the Na+/H+ antiporter NhaA from Escherichia coli, and the mitochondrial carrier AAC2 from Saccharomyces cerevisiae. For all transporters kinetic parameters, such as KM, IMAX, and pH dependency, were evaluated. This robust and expedite workflow (e.g., can be executed within only five workdays) offers a convenient direct functional assessment of transporter protein activity and has the ability to facilitate applications of transporters in medical and biotechnological research.
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Affiliation(s)
- Fang Dong
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Denmark
| | - Pawel Lojko
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Denmark
| | | | - Frank Bernhard
- Institute of Biophysical Chemistry, Centre for Biomolecular Magnetic Resonance, J.W. Goethe-University, Frankfurt am Main, Germany
| | - Irina Borodina
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Denmark.
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Körner A, Bazzone A, Wichert M, Barthmes M, Dondapati SK, Fertig N, Kubick S. Unraveling the kinetics and pharmacology of human PepT1 using solid supported membrane-based electrophysiology. Bioelectrochemistry 2024; 155:108573. [PMID: 37748262 DOI: 10.1016/j.bioelechem.2023.108573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 09/14/2023] [Accepted: 09/15/2023] [Indexed: 09/27/2023]
Abstract
The human Peptide Transporter 1 (hPepT1) is known for its broad substrate specificity and its ability to transport (pro-)drugs. Here, we present an in-depth comprehensive study of hPepT1 and its interactions with various substrates via solid supported membrane-based electrophysiology (SSME). Using hPepT1-containing vesicles, we could not identify any peptide induced pre-steady-state currents, indicating that the recorded peak currents reflect steady-state transport. Electrogenic co-transport of H+/glycylglycine (GlyGly) was observed across a pH range of 5.0 to 9.0. The pH dependence is described by a bell-shaped activity curve and two pK values. KM and relative Vmax values of various canonical and non-canonical peptide substrates were contextualized with current mechanistic understandings of hPepT1. Finally, specific inhibition was observed for various inhibitors in a high throughput format, and IC50 values are reported. Taken together, these findings contribute to promoting the design and analysis of pharmacologically relevant substances.
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Affiliation(s)
- Alexander Körner
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg 13, 14476 Potsdam, Germany; Institute of Biotechnology, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany
| | - Andre Bazzone
- Nanion Technologies GmbH, Ganghoferstr. 70a, 80339 Munich, Germany
| | - Maximilian Wichert
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg 13, 14476 Potsdam, Germany; Freie Universität Berlin, Institute of Chemistry and Biochemistry - Biochemistry, 14195 Berlin, Germany
| | - Maria Barthmes
- Nanion Technologies GmbH, Ganghoferstr. 70a, 80339 Munich, Germany
| | - Srujan Kumar Dondapati
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg 13, 14476 Potsdam, Germany.
| | - Niels Fertig
- Nanion Technologies GmbH, Ganghoferstr. 70a, 80339 Munich, Germany
| | - Stefan Kubick
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg 13, 14476 Potsdam, Germany; Freie Universität Berlin, Institute of Chemistry and Biochemistry - Biochemistry, 14195 Berlin, Germany; Faculty of Health Sciences, Joint Faculty of the Brandenburg University of Technology Cottbus - Senftenberg, The Brandenburg Medical School Theodor Fontane and the University of Potsdam, Germany
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Bazzone A, Barthmes M, George C, Brinkwirth N, Zerlotti R, Prinz V, Cole K, Friis S, Dickson A, Rice S, Lim J, Fern Toh M, Mohammadi M, Pau D, Stone DJ, Renger JJ, Fertig N. A Comparative Study on the Lysosomal Cation Channel TMEM175 Using Automated Whole-Cell Patch-Clamp, Lysosomal Patch-Clamp, and Solid Supported Membrane-Based Electrophysiology: Functional Characterization and High-Throughput Screening Assay Development. Int J Mol Sci 2023; 24:12788. [PMID: 37628970 PMCID: PMC10454728 DOI: 10.3390/ijms241612788] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 08/09/2023] [Accepted: 08/12/2023] [Indexed: 08/27/2023] Open
Abstract
The lysosomal cation channel TMEM175 is a Parkinson's disease-related protein and a promising drug target. Unlike whole-cell automated patch-clamp (APC), lysosomal patch-clamp (LPC) facilitates physiological conditions, but is not yet suitable for high-throughput screening (HTS) applications. Here, we apply solid supported membrane-based electrophysiology (SSME), which enables both direct access to lysosomes and high-throughput electrophysiological recordings. In SSME, ion translocation mediated by TMEM175 is stimulated using a concentration gradient at a resting potential of 0 mV. The concentration-dependent K+ response exhibited an I/c curve with two distinct slopes, indicating the existence of two conducting states. We measured H+ fluxes with a permeability ratio of PH/PK = 48,500, which matches literature findings from patch-clamp studies, validating the SSME approach. Additionally, TMEM175 displayed a high pH dependence. Decreasing cytosolic pH inhibited both K+ and H+ conductivity of TMEM175. Conversely, lysosomal pH and pH gradients did not have major effects on TMEM175. Finally, we developed HTS assays for drug screening and evaluated tool compounds (4-AP, Zn as inhibitors; DCPIB, arachidonic acid, SC-79 as enhancers) using SSME and APC. Additionally, we recorded EC50 data for eight blinded TMEM175 enhancers and compared the results across all three assay technologies, including LPC, discussing their advantages and disadvantages.
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Affiliation(s)
- Andre Bazzone
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
| | - Maria Barthmes
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
| | - Cecilia George
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
| | - Nina Brinkwirth
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
| | - Rocco Zerlotti
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
- RIGeL-Regensburg International Graduate School of Life Sciences, University of Regensburg, 93053 Regensburg, Germany
| | - Valentin Prinz
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
| | - Kim Cole
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
| | - Søren Friis
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
| | - Alexander Dickson
- SB Drug Discovery, West of Scotland Science Park, Glasgow G20 0XA, UK; (A.D.); (S.R.)
| | - Simon Rice
- SB Drug Discovery, West of Scotland Science Park, Glasgow G20 0XA, UK; (A.D.); (S.R.)
| | - Jongwon Lim
- Cerevel Therapeutics, 222 Jacobs St, Cambridge, MA 02141, USA; (J.L.); (M.F.T.); (D.J.S.); (J.J.R.)
| | - May Fern Toh
- Cerevel Therapeutics, 222 Jacobs St, Cambridge, MA 02141, USA; (J.L.); (M.F.T.); (D.J.S.); (J.J.R.)
| | | | - Davide Pau
- SB Drug Discovery, West of Scotland Science Park, Glasgow G20 0XA, UK; (A.D.); (S.R.)
| | - David J. Stone
- Cerevel Therapeutics, 222 Jacobs St, Cambridge, MA 02141, USA; (J.L.); (M.F.T.); (D.J.S.); (J.J.R.)
| | - John J. Renger
- Cerevel Therapeutics, 222 Jacobs St, Cambridge, MA 02141, USA; (J.L.); (M.F.T.); (D.J.S.); (J.J.R.)
| | - Niels Fertig
- Nanion Technologies, Ganghoferstr. 70a, 80339 Munich, Germany (V.P.); (S.F.)
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Pommereau A, Licher T, Bärenz F. Solid-Supported Membrane (SSM)-Based Electrophysiology Assays Using Surface Electrogenic Event Reader Technology (SURFE²R) in Early Drug Discovery. Curr Protoc 2023; 3:e650. [PMID: 36912603 DOI: 10.1002/cpz1.650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2023]
Abstract
This article presents detailed descriptions of procedures and troubleshooting tips for solid-supported membrane (SSM)-based electrophysiology assays (SURFE²R) to measure electrogenic solute carrier transporter proteins (SLCs) and assess the effects of compounds that modulate their activity. SURFE²R allows the use of the standard 96-well format, making it an ideal platform for tertiary assays in a drug-discovery campaign. The assays are performed with cell-line-derived membrane fractions or proteoliposomes containing the transporter of interest. Three main protocols are described for the isolation of membrane fractions from cell culture and the generation of proteoliposomes containing the transporter of interest. Additionally, detailed protocols for SURFE²R single concentration and dose-response experiments are included to measure the potencies of test compounds in stimulating or inhibiting transporter function (EC50 or IC50 values, respectively) and kinetic functional assays to calculate apparent affinity (kM ) and maximal velocity (Vmax ) of substrate uptake. © 2023 Sanofi. Current Protocols published by Wiley Periodicals LLC. PROTOCOL GROUP 1: Sample preparation for SSM-based electrophysiology assays Support Protocol 1: Production of cell batches Support Protocol 2: Simple isolation of cell membranes Alternate Protocol 1: Isolation of cell membranes with sucrose gradient pre-purification Support Protocol 3: Production and isolation of liposomes Support Protocol 4: Preparation of sensor with isolated cell membranes Alternate Protocol 2: Preparation of sensor with isolated proteoliposomes PROTOCOL GROUP 2: Determination of assay parameters for SSM-based electrophysiology assay Support Protocol 5: Assay with stable buffer Alternate Protocol 3: Assay with ion gradient Support Protocol 6: Determination of membrane/liposome concentration Support Protocol 7: Determination of substrate dependency kM PROTOCOL GROUP 3: Determination of advanced assay parameters for SSM-based electrophysiology assays Support Protocol 8: Assessment of ion concentration dependency Support Protocol 9: Assessment of pH dependency Support Protocol 10: Assessment of DMSO dependency Support Protocol 11: Assessment of signal stability with multiple activations PROTOCOL GROUP 4: Compound testing through SSM-based electrophysiology assays using SURFE²R apparatus Support Protocol 12: Assessment of signal specificity of a published inhibitor or unknown compound(s) Support Protocol 13: Compound wash-out Support Protocol 14: Statistical analysis.
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Affiliation(s)
- Antje Pommereau
- Sanofi, Integrated Drug Discovery, Industriepark Hoechst, Frankfurt am Main, Germany
| | - Thomas Licher
- Sanofi, Integrated Drug Discovery, Industriepark Hoechst, Frankfurt am Main, Germany
| | - Felix Bärenz
- Sanofi, Integrated Drug Discovery, Industriepark Hoechst, Frankfurt am Main, Germany
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Bazzone A, Zerlotti R, Barthmes M, Fertig N. Functional characterization of SGLT1 using SSM-based electrophysiology: Kinetics of sugar binding and translocation. Front Physiol 2023; 14:1058583. [PMID: 36824475 PMCID: PMC9941201 DOI: 10.3389/fphys.2023.1058583] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 01/17/2023] [Indexed: 02/10/2023] Open
Abstract
Beside the ongoing efforts to determine structural information, detailed functional studies on transporters are essential to entirely understand the underlying transport mechanisms. We recently found that solid supported membrane-based electrophysiology (SSME) enables the measurement of both sugar binding and transport in the Na+/sugar cotransporter SGLT1 (Bazzone et al, 2022a). Here, we continued with a detailed kinetic characterization of SGLT1 using SSME, determining KM and KD app for different sugars, kobs values for sugar-induced conformational transitions and the effects of Na+, Li+, H+ and Cl- on sugar binding and transport. We found that the sugar-induced pre-steady-state (PSS) charge translocation varies with the bound ion (Na+, Li+, H+ or Cl-), but not with the sugar species, indicating that the conformational state upon sugar binding depends on the ion. Rate constants for the sugar-induced conformational transitions upon binding to the Na+-bound carrier range from 208 s-1 for D-glucose to 95 s-1 for 3-OMG. In the absence of Na+, rate constants are decreased, but all sugars bind to the empty carrier. From the steady-state transport current, we found a sequence for sugar specificity (Vmax/KM): D-glucose > MDG > D-galactose > 3-OMG > D-xylose. While KM differs 160-fold across tested substrates and plays a major role in substrate specificity, Vmax only varies by a factor of 1.9. Interestingly, D-glucose has the lowest Vmax across all tested substrates, indicating a rate limiting step in the sugar translocation pathway following the fast sugar-induced electrogenic conformational transition. SGLT1 specificity for D-glucose is achieved by optimizing two ratios: the sugar affinity of the empty carrier for D-glucose is similarly low as for all tested sugars (KD,K app = 210 mM). Affinity for D-glucose increases 14-fold (KD,Na app = 15 mM) in the presence of sodium as a result of cooperativity. Apparent affinity for D-glucose during transport increases 8-fold (KM = 1.9 mM) compared to KD,Na app due to optimized kinetics. In contrast, KM and KD app values for 3-OMG and D-xylose are of similar magnitude. Based on our findings we propose an 11-state kinetic model, introducing a random binding order and intermediate states corresponding to the electrogenic transitions detected via SSME upon substrate binding.
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Affiliation(s)
- Andre Bazzone
- Nanion Technologies GmbH, Munich, Germany,*Correspondence: Andre Bazzone,
| | - Rocco Zerlotti
- Nanion Technologies GmbH, Munich, Germany,Department of Structural Biology, Faculty of Biology and Pre-Clinics, Institute of Biochemistry, Genetics and Microbiology, University of Regensburg, Regensburg, Germany
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Dvorak V, Wiedmer T, Ingles-Prieto A, Altermatt P, Batoulis H, Bärenz F, Bender E, Digles D, Dürrenberger F, Heitman LH, IJzerman AP, Kell DB, Kickinger S, Körzö D, Leippe P, Licher T, Manolova V, Rizzetto R, Sassone F, Scarabottolo L, Schlessinger A, Schneider V, Sijben HJ, Steck AL, Sundström H, Tremolada S, Wilhelm M, Wright Muelas M, Zindel D, Steppan CM, Superti-Furga G. An Overview of Cell-Based Assay Platforms for the Solute Carrier Family of Transporters. Front Pharmacol 2021; 12:722889. [PMID: 34447313 PMCID: PMC8383457 DOI: 10.3389/fphar.2021.722889] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 07/19/2021] [Indexed: 12/12/2022] Open
Abstract
The solute carrier (SLC) superfamily represents the biggest family of transporters with important roles in health and disease. Despite being attractive and druggable targets, the majority of SLCs remains understudied. One major hurdle in research on SLCs is the lack of tools, such as cell-based assays to investigate their biological role and for drug discovery. Another challenge is the disperse and anecdotal information on assay strategies that are suitable for SLCs. This review provides a comprehensive overview of state-of-the-art cellular assay technologies for SLC research and discusses relevant SLC characteristics enabling the choice of an optimal assay technology. The Innovative Medicines Initiative consortium RESOLUTE intends to accelerate research on SLCs by providing the scientific community with high-quality reagents, assay technologies and data sets, and to ultimately unlock SLCs for drug discovery.
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Affiliation(s)
- Vojtech Dvorak
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Tabea Wiedmer
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Alvaro Ingles-Prieto
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | | | - Helena Batoulis
- Drug Discovery Sciences–Lead Discovery, Bayer Pharmaceuticals, Wuppertal, Germany
| | - Felix Bärenz
- Sanofi-Aventis Deutschland GmbH, Frankfurt am Main, Germany
| | - Eckhard Bender
- Drug Discovery Sciences–Lead Discovery, Bayer Pharmaceuticals, Wuppertal, Germany
| | - Daniela Digles
- Department of Pharmaceutical Sciences, University of Vienna, Vienna, Austria
| | | | - Laura H. Heitman
- Division of Drug Discovery and Safety, LACDR, Leiden University, Leiden, Netherlands
| | - Adriaan P. IJzerman
- Division of Drug Discovery and Safety, LACDR, Leiden University, Leiden, Netherlands
| | - Douglas B. Kell
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, United Kingdom
- Novo Nordisk Foundation Centre for Biosustainability, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Stefanie Kickinger
- Department of Pharmaceutical Sciences, University of Vienna, Vienna, Austria
| | - Daniel Körzö
- Department of Pharmaceutical Sciences, University of Vienna, Vienna, Austria
| | - Philipp Leippe
- Department of Chemical Biology, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Thomas Licher
- Sanofi-Aventis Deutschland GmbH, Frankfurt am Main, Germany
| | | | | | | | | | - Avner Schlessinger
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Vanessa Schneider
- Department of Pharmaceutical Sciences, University of Vienna, Vienna, Austria
| | - Hubert J. Sijben
- Division of Drug Discovery and Safety, LACDR, Leiden University, Leiden, Netherlands
| | | | | | | | | | - Marina Wright Muelas
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Diana Zindel
- Drug Discovery Sciences–Lead Discovery, Bayer Pharmaceuticals, Wuppertal, Germany
| | - Claire M. Steppan
- Pfizer Worldwide Research, Development and Medical, Groton, MA, United States
| | - Giulio Superti-Furga
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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