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Menon I, Sych T, Son Y, Morizumi T, Lee J, Ernst OP, Khelashvili G, Sezgin E, Levitz J, Menon AK. A cholesterol switch controls phospholipid scrambling by G protein-coupled receptors. J Biol Chem 2024; 300:105649. [PMID: 38237683 PMCID: PMC10874734 DOI: 10.1016/j.jbc.2024.105649] [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: 11/25/2023] [Revised: 01/04/2024] [Accepted: 01/07/2024] [Indexed: 01/30/2024] Open
Abstract
Class A G protein-coupled receptors (GPCRs), a superfamily of cell membrane signaling receptors, moonlight as constitutively active phospholipid scramblases. The plasma membrane of metazoan cells is replete with GPCRs yet has a strong resting trans-bilayer phospholipid asymmetry, with the signaling lipid phosphatidylserine confined to the cytoplasmic leaflet. To account for the persistence of this lipid asymmetry in the presence of GPCR scramblases, we hypothesized that GPCR-mediated lipid scrambling is regulated by cholesterol, a major constituent of the plasma membrane. We now present a technique whereby synthetic vesicles reconstituted with GPCRs can be supplemented with cholesterol to a level similar to that of the plasma membrane and show that the scramblase activity of two prototypical GPCRs, opsin and the β1-adrenergic receptor, is impaired upon cholesterol loading. Our data suggest that cholesterol acts as a switch, inhibiting scrambling above a receptor-specific threshold concentration to disable GPCR scramblases at the plasma membrane.
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Affiliation(s)
- Indu Menon
- Department of Biochemistry, Weill Cornell Medical College, New York, New York, USA
| | - Taras Sych
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden
| | - Yeeun Son
- Graduate program in Biochemistry, Cell and Molecular Biology, Weill Cornell Graduate School, New York, New York, USA; Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York, USA
| | - Takefumi Morizumi
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Joon Lee
- Department of Biochemistry, Weill Cornell Medical College, New York, New York, USA
| | - Oliver P Ernst
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada; Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - George Khelashvili
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, New York, USA; Institute of Computational Biomedicine, Weill Cornell Medical College, New York, New York, USA
| | - Erdinc Sezgin
- Graduate program in Biochemistry, Cell and Molecular Biology, Weill Cornell Graduate School, New York, New York, USA
| | - Joshua Levitz
- Department of Biochemistry, Weill Cornell Medical College, New York, New York, USA
| | - Anant K Menon
- Department of Biochemistry, Weill Cornell Medical College, New York, New York, USA.
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Menon I, Sych T, Son Y, Morizumi T, Lee J, Ernst OP, Khelashvili G, Sezgin E, Levitz J, Menon AK. A cholesterol switch controls phospholipid scrambling by G protein-coupled receptors. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.11.24.568580. [PMID: 38045315 PMCID: PMC10690279 DOI: 10.1101/2023.11.24.568580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Class A G protein-coupled receptors (GPCRs), a superfamily of cell membrane signaling receptors, moonlight as constitutively active phospholipid scramblases. The plasma membrane of metazoan cells is replete with GPCRs, yet has a strong resting trans-bilayer phospholipid asymmetry, with the signaling lipid phosphatidylserine confined to the cytoplasmic leaflet. To account for the persistence of this lipid asymmetry in the presence of GPCR scramblases, we hypothesized that GPCR-mediated lipid scrambling is regulated by cholesterol, a major constituent of the plasma membrane. We now present a technique whereby synthetic vesicles reconstituted with GPCRs can be supplemented with cholesterol to a level similar to that of the plasma membrane and show that the scramblase activity of two prototypical GPCRs, opsin and the β1-adrenergic receptor, is impaired upon cholesterol loading. Our data suggest that cholesterol acts as a switch, inhibiting scrambling above a receptor-specific threshold concentration to disable GPCR scramblases at the plasma membrane.
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Affiliation(s)
- Indu Menon
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065, USA
| | - Taras Sych
- Science for Life Laboratory, Department of Women’s and Children’s Health, Karolinska Institutet, 17165 Solna, Sweden
| | - Yeeun Son
- Graduate program in Biochemistry, Cell and Molecular Biology, Weill Cornell Graduate School, New York, NY 10065, USA
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Takefumi Morizumi
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada M5S 1A8
| | - Joon Lee
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065, USA
| | - Oliver P. Ernst
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada M5S 1A8
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada M5S 1A8
| | - George Khelashvili
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10065, USA
- Institute of Computational Biomedicine, Weill Cornell Medical College, New York, NY 10065, USA
| | - Erdinc Sezgin
- Graduate program in Biochemistry, Cell and Molecular Biology, Weill Cornell Graduate School, New York, NY 10065, USA
| | - Joshua Levitz
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065, USA
| | - Anant K. Menon
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065, USA
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Herrera SA, Günther Pomorski T. Reconstitution of ATP-dependent lipid transporters: gaining insight into molecular characteristics, regulation, and mechanisms. Biosci Rep 2023; 43:BSR20221268. [PMID: 37417269 PMCID: PMC10412526 DOI: 10.1042/bsr20221268] [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: 04/26/2023] [Revised: 06/30/2023] [Accepted: 07/06/2023] [Indexed: 07/08/2023] Open
Abstract
Lipid transporters play a crucial role in supporting essential cellular processes such as organelle assembly, vesicular trafficking, and lipid homeostasis by driving lipid transport across membranes. Cryo-electron microscopy has recently resolved the structures of several ATP-dependent lipid transporters, but functional characterization remains a major challenge. Although studies of detergent-purified proteins have advanced our understanding of these transporters, in vitro evidence for lipid transport is still limited to a few ATP-dependent lipid transporters. Reconstitution into model membranes, such as liposomes, is a suitable approach to study lipid transporters in vitro and to investigate their key molecular features. In this review, we discuss the current approaches for reconstituting ATP-driven lipid transporters into large liposomes and common techniques used to study lipid transport in proteoliposomes. We also highlight the existing knowledge on the regulatory mechanisms that modulate the activity of lipid transporters, and finally, we address the limitations of the current approaches and future perspectives in this field.
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Affiliation(s)
- Sara Abad Herrera
- Department of Molecular Biochemistry, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Bochum, Germany
| | - Thomas Günther Pomorski
- Department of Molecular Biochemistry, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Bochum, Germany
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
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Veit S, Paweletz LC, Günther Pomorski T. Determination of membrane protein orientation upon liposomal reconstitution down to the single vesicle level. Biol Chem 2023; 404:647-661. [PMID: 36857289 DOI: 10.1515/hsz-2022-0325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 02/07/2023] [Indexed: 03/02/2023]
Abstract
Reconstitution of membrane proteins into liposomal membranes represents a key technique in enabling functional analysis under well-defined conditions. In this review, we provide a brief introduction to selected methods that have been developed to determine membrane protein orientation after reconstitution in liposomes, including approaches based on proteolytic digestion with proteases, site-specific labeling, fluorescence quenching and activity assays. In addition, we briefly highlight new strategies based on single vesicle analysis to address the problem of sample heterogeneity.
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Affiliation(s)
- Sarina Veit
- Department of Molecular Biochemistry , Faculty of Chemistry and Biochemistry , NC 7/174, Ruhr University Bochum, Universitätsstraße 150, D-44780 Bochum, Germany
| | - Laura Charlotte Paweletz
- Department of Molecular Biochemistry , Faculty of Chemistry and Biochemistry , NC 7/174, Ruhr University Bochum, Universitätsstraße 150, D-44780 Bochum, Germany
| | - Thomas Günther Pomorski
- Department of Molecular Biochemistry , Faculty of Chemistry and Biochemistry , NC 7/174, Ruhr University Bochum, Universitätsstraße 150, D-44780 Bochum, Germany
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark
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