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Sebinelli HG, Syska C, Čopič A, Lenoir G. Established and emerging players in phospholipid scrambling: a structural perspective. Biochimie 2024:S0300-9084(24)00218-9. [PMID: 39304020 DOI: 10.1016/j.biochi.2024.09.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 09/16/2024] [Accepted: 09/17/2024] [Indexed: 09/22/2024]
Abstract
The maintenance of a diverse and non-homogeneous lipid composition in cell membranes is crucial for a multitude of cellular processes. One important example is transbilayer lipid asymmetry, which refers to a difference in lipid composition between the two leaflets of a cellular membrane. Transbilayer asymmetry is especially pronounced at the plasma membrane, where at resting state, negatively-charged phospholipids such as phosphatidylserine (PS) are almost exclusively restricted to the cytosolic leaflet, whereas sphingolipids are mostly found in the exoplasmic leaflet. Transbilayer movement of lipids is inherently slow, and for a fast cellular response, for example during apoptosis, transmembrane proteins termed scramblases facilitate the movement of polar/charged lipid headgroups through the membrane interior. In recent years, an expanding number of proteins from diverse families have been suggested to possess a lipid scramblase activity. Members of TMEM16 and XKR proteins have been implicated in blood clotting and apoptosis, whereas the scrambling activity of ATG9 and TMEM41B/VMP1 proteins contributes to the synthesis of autophagosomal membrane during autophagy. Structural studies, in vitro reconstitution of lipid scrambling, and molecular dynamics simulations have significantly advanced our understanding of the molecular mechanisms of lipid scrambling and helped delineate potential lipid transport pathways through the membrane. A number of examples also suggest that lipid scrambling activity can be combined with another activity, as is the case for TMEM16 proteins, which also function as ion channels, rhodopsin in the photoreceptor membrane, and possibly other G-protein coupled receptors.
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Affiliation(s)
- Heitor Gobbi Sebinelli
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell, Gif-sur-Yvette, France
| | - Camille Syska
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, 34293, Montpellier Cedex 05, France
| | - Alenka Čopič
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, 34293, Montpellier Cedex 05, France
| | - Guillaume Lenoir
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell, Gif-sur-Yvette, France.
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2
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Herrera SA, Justesen BH, Dieudonné T, Montigny C, Nissen P, Lenoir G, Günther Pomorski T. Direct evidence of lipid transport by the Drs2-Cdc50 flippase upon truncation of its terminal regions. Protein Sci 2023; 33:e4855. [PMID: 38063271 PMCID: PMC10895448 DOI: 10.1002/pro.4855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Revised: 11/15/2023] [Accepted: 12/02/2023] [Indexed: 02/27/2024]
Abstract
P4-ATPases in complex with Cdc50 subunits are lipid flippases that couple ATP hydrolysis with lipid transport to the cytoplasmic leaflet of membranes to create lipid asymmetry. Such vectorial transport has been shown to contribute to vesicle formation in the late secretory pathway. Some flippases are regulated by autoinhibitory regions that can be destabilized by protein kinase-mediated phosphorylation and possibly by binding of cytosolic proteins. In addition, the binding of lipids to flippases may also induce conformational changes required for the activity of these transporters. Here, we address the role of phosphatidylinositol-4-phosphate (PI4P) and the terminal autoinhibitory tails on the lipid flipping activity of the yeast lipid flippase Drs2-Cdc50. By functionally reconstituting the full-length and truncated forms of Drs2 in a 1:1 complex with the Cdc50 subunit, we provide compelling evidence that lipid flippase activity is exclusively detected for the truncated Drs2 variant and is dependent on the presence of the phosphoinositide PI4P. These findings highlight the critical role of phosphoinositides as lipid co-factors in the regulation of lipid transport by the Drs2-Cdc50 flippase.
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Affiliation(s)
- Sara Abad Herrera
- Department of Molecular Biochemistry, Faculty of Chemistry and BiochemistryRuhr University BochumBochumGermany
| | - Bo Højen Justesen
- Department of Molecular Biochemistry, Faculty of Chemistry and BiochemistryRuhr University BochumBochumGermany
| | - Thibaud Dieudonné
- Université Paris‐Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC)Gif‐sur‐YvetteFrance
- DANDRITE, Nordic EMBL Partnership for Molecular Medicine, Department of Molecular Biology and GeneticsAarhus UniversityAarhusDenmark
| | - Cédric Montigny
- Université Paris‐Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC)Gif‐sur‐YvetteFrance
| | - Poul Nissen
- DANDRITE, Nordic EMBL Partnership for Molecular Medicine, Department of Molecular Biology and GeneticsAarhus UniversityAarhusDenmark
| | - Guillaume Lenoir
- Université Paris‐Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC)Gif‐sur‐YvetteFrance
| | - Thomas Günther Pomorski
- Department of Molecular Biochemistry, Faculty of Chemistry and BiochemistryRuhr University BochumBochumGermany
- Department of Plant and Environmental SciencesUniversity of CopenhagenFrederiksbergDenmark
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3
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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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4
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Baum JF, Bredegaard L, Herrera SA, Pomorski TG. Visualizing NBD-lipid Uptake in Mammalian Cells by Confocal Microscopy. Bio Protoc 2023; 13:e4771. [PMID: 37456343 PMCID: PMC10338633 DOI: 10.21769/bioprotoc.4771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 04/11/2023] [Accepted: 06/04/2023] [Indexed: 07/18/2023] Open
Abstract
Eukaryotic cells use a series of membrane transporters to control the movement of lipids across their plasma membrane. Several tools and techniques have been developed to analyze the activity of these transporters in the plasma membrane of mammalian cells. Among them, assays based on fluorescence microscopy in combination with fluorescent lipid probes are particularly suitable, allowing visualization of lipid internalization in living cells. Here, we provide a step-by-step protocol for mammalian cell culture, lipid probe preparation, cell labeling, and confocal imaging to monitor lipid internalization by lipid flippases at the plasma membrane based on lipid probes carrying a fluorophore at a short-chain fatty acid. The protocol allows studying a wide range of mammalian cell lines, to test the impact of gene knockouts on lipid internalization at the plasma membrane and changes in lipid uptake during cell differentiation. Key features Visualization and quantification of lipid internalization by lipid flippases at the plasma membrane based on confocal microscopy. Assay is performed on living adherent mammalian cells in culture. The protocol can be easily modified to a wide variety of mammalian cell lines.
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Affiliation(s)
- Julia F. Baum
- 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
| | - Lasse Bredegaard
- 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
| | - 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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5
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Zhang H, Zhang Y, Xu P, Bai C. Exploring the Phospholipid Transport Mechanism of ATP8A1-CDC50. Biomedicines 2023; 11:biomedicines11020546. [PMID: 36831082 PMCID: PMC9953615 DOI: 10.3390/biomedicines11020546] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 02/09/2023] [Accepted: 02/10/2023] [Indexed: 02/16/2023] Open
Abstract
P4-ATPase translocates lipids from the exoplasmic to the cytosolic plasma membrane leaflet to maintain lipid asymmetry distribution in eukaryotic cells. P4-ATPase is associated with severe neurodegenerative and metabolic diseases such as neurological and motor disorders. Thus, it is important to understand its transport mechanism. However, even with progress in X-ray diffraction and cryo-electron microscopy techniques, it is difficult to obtain the dynamic information of the phospholipid transport process in detail. There are still some problems required to be resolved: (1) when does the lipid transport happen? (2) How do the key residues on the transmembrane helices contribute to the free energy of important states? In this work, we explore the phospholipid transport mechanism using a coarse-grained model and binding free energy calculations. We obtained the free energy landscape by coupling the protein conformational changes and the phospholipid transport event, taking ATP8A1-CDC50 (the typical subtype of P4-ATPase) as the research object. According to the results, we found that the phospholipid would bind to the ATP8A1-CDC50 at the early stage when ATP8A1-CDC50 changes from E2P to E2Pi-PL state. We also found that the electrostatic effects play crucial roles in the phospholipid transport process. The information obtained from this work could help us in designing novel drugs for P-type flippase disorders.
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Affiliation(s)
- Honghui Zhang
- Warshel Institute for Computational Biology, School of Life and Health Sciences, School of Medicine, The Chinese University of Hong Kong, Shenzhen 518172, China
| | - Yue Zhang
- Warshel Institute for Computational Biology, School of Life and Health Sciences, School of Medicine, The Chinese University of Hong Kong, Shenzhen 518172, China
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei 230026, China
| | - Peiyi Xu
- Warshel Institute for Computational Biology, School of Life and Health Sciences, School of Medicine, The Chinese University of Hong Kong, Shenzhen 518172, China
| | - Chen Bai
- Warshel Institute for Computational Biology, School of Life and Health Sciences, School of Medicine, The Chinese University of Hong Kong, Shenzhen 518172, China
- Chenzhu (MoMeD) Biotechnology Co., Ltd., Hangzhou 310005, China
- Correspondence:
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6
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Mathiassen PPM, Pomorski TG. A Fluorescence-based Assay for Measuring Phospholipid Scramblase Activity in Giant Unilamellar Vesicles. Bio Protoc 2022; 12:e4366. [PMID: 35434199 PMCID: PMC8983165 DOI: 10.21769/bioprotoc.4366] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Revised: 11/09/2021] [Accepted: 03/01/2022] [Indexed: 07/28/2023] Open
Abstract
Transbilayer movement of phospholipids in biological membranes is mediated by a diverse set of lipid transporters. Among them are scramblases that facilitate rapid bi-directional movement of lipids without metabolic energy input. In this protocol, we describe the incorporation of phospholipid scramblases into giant unilamellar vesicles (GUVs) formed from scramblase-containing large unilamellar vesicles by electroformation. We also describe how to analyze their activity using membrane-impermeant sodium dithionite, to bleach symmetrically incorporated fluorescent ATTO488-conjugated phospholipids. The fluorescence-based readout allows single vesicle tracking for a large number of settled/immobilized GUVs, and provides a well-defined experimental setup to directly characterize these lipid transporters at the molecular level. Graphic abstract: Giant unilamellar vesicles (GUVs) are formed by electroformation from large unilamellar vesicles (LUVs) containing phospholipid scramblases (purple) and trace amounts of a fluorescent lipid reporter (green). The scramblase activity is analyzed by a fluorescence-based assay of single GUVs, using the membrane-impermeant quencher dithionite. Sizes not to scale. Modified from Mathiassen et al. (2021).
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Affiliation(s)
- Patricia P. M. Mathiassen
- Department of Molecular Biochemistry, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, 44780, Bochum, Germany
| | - Thomas Günther Pomorski
- Department of Molecular Biochemistry, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, 44780, Bochum, Germany
- Department of Plant and Environmental Sciences, University of Copenhagen, 1871, Frederiksberg C, Denmark
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7
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Herrera SA, Grifell-Junyent M, Pomorski TG. NBD-lipid Uptake Assay for Mammalian Cell Lines. Bio Protoc 2022; 12:e4330. [PMID: 35340299 PMCID: PMC8899549 DOI: 10.21769/bioprotoc.4330] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 10/14/2021] [Accepted: 01/23/2022] [Indexed: 07/28/2023] Open
Abstract
All eukaryotic cells are equipped with transmembrane lipid transporters, which are key players in membrane lipid asymmetry, vesicular trafficking, and membrane fusion. The link between mutations in these transporters and disease in humans highlights their essential role in cell homeostasis. Yet, many key features of their activities, their substrate specificity, and their regulation remain to be elucidated. Here, we describe an optimized quantitative flow cytometry-based lipid uptake assay utilizing nitrobenzoxadiazolyl (NBD) fluorescent lipids to study lipid internalization in mammalian cell lines, which allows characterizing lipid transporter activities at the plasma membrane. This approach allows for a rapid analysis of large cell populations, thereby greatly reducing sampling variability. The protocol can be applied to study a wide range of mammalian cell lines, to test the impact of gene knockouts on lipid internalization at the plasma membrane, and to uncover the dynamics of lipid transport at the plasma membrane. Graphic abstract: Internalization of NBD-labeled lipids from the plasma membrane of CHO-K1 cells.
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Affiliation(s)
- Sara Abad Herrera
- Department of Molecular Biochemistry, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Bochum, Germany
| | - Marta Grifell-Junyent
- 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
| | - 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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8
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Egea PF. Mechanisms of Non-Vesicular Exchange of Lipids at Membrane Contact Sites: Of Shuttles, Tunnels and, Funnels. Front Cell Dev Biol 2021; 9:784367. [PMID: 34912813 PMCID: PMC8667587 DOI: 10.3389/fcell.2021.784367] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 11/08/2021] [Indexed: 11/13/2022] Open
Abstract
Eukaryotic cells are characterized by their exquisite compartmentalization resulting from a cornucopia of membrane-bound organelles. Each of these compartments hosts a flurry of biochemical reactions and supports biological functions such as genome storage, membrane protein and lipid biosynthesis/degradation and ATP synthesis, all essential to cellular life. Acting as hubs for the transfer of matter and signals between organelles and throughout the cell, membrane contacts sites (MCSs), sites of close apposition between membranes from different organelles, are essential to cellular homeostasis. One of the now well-acknowledged function of MCSs involves the non-vesicular trafficking of lipids; its characterization answered one long-standing question of eukaryotic cell biology revealing how some organelles receive and distribute their membrane lipids in absence of vesicular trafficking. The endoplasmic reticulum (ER) in synergy with the mitochondria, stands as the nexus for the biosynthesis and distribution of phospholipids (PLs) throughout the cell by contacting nearly all other organelle types. MCSs create and maintain lipid fluxes and gradients essential to the functional asymmetry and polarity of biological membranes throughout the cell. Membrane apposition is mediated by proteinaceous tethers some of which function as lipid transfer proteins (LTPs). We summarize here the current state of mechanistic knowledge of some of the major classes of LTPs and tethers based on the available atomic to near-atomic resolution structures of several "model" MCSs from yeast but also in Metazoans; we describe different models of lipid transfer at MCSs and analyze the determinants of their specificity and directionality. Each of these systems illustrate fundamental principles and mechanisms for the non-vesicular exchange of lipids between eukaryotic membrane-bound organelles essential to a wide range of cellular processes such as at PL biosynthesis and distribution, lipid storage, autophagy and organelle biogenesis.
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Affiliation(s)
- Pascal F Egea
- Department of Biological Chemistry, David Geffen School of Medicine, UCLA, Los Angeles, CA, United States
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9
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Lenoir G, D'Ambrosio JM, Dieudonné T, Čopič A. Transport Pathways That Contribute to the Cellular Distribution of Phosphatidylserine. Front Cell Dev Biol 2021; 9:737907. [PMID: 34540851 PMCID: PMC8440936 DOI: 10.3389/fcell.2021.737907] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 08/10/2021] [Indexed: 12/05/2022] Open
Abstract
Phosphatidylserine (PS) is a negatively charged phospholipid that displays a highly uneven distribution within cellular membranes, essential for establishment of cell polarity and other processes. In this review, we discuss how combined action of PS biosynthesis enzymes in the endoplasmic reticulum (ER), lipid transfer proteins (LTPs) acting within membrane contact sites (MCS) between the ER and other compartments, and lipid flippases and scramblases that mediate PS flip-flop between membrane leaflets controls the cellular distribution of PS. Enrichment of PS in specific compartments, in particular in the cytosolic leaflet of the plasma membrane (PM), requires input of energy, which can be supplied in the form of ATP or by phosphoinositides. Conversely, coupling between PS synthesis or degradation, PS flip-flop and PS transfer may enable PS transfer by passive flow. Such scenario is best documented by recent work on the formation of autophagosomes. The existence of lateral PS nanodomains, which is well-documented in the case of the PM and postulated for other compartments, can change the steepness or direction of PS gradients between compartments. Improvements in cellular imaging of lipids and membranes, lipidomic analysis of complex cellular samples, reconstitution of cellular lipid transport reactions and high-resolution structural data have greatly increased our understanding of cellular PS homeostasis. Our review also highlights how budding yeast has been instrumental for our understanding of the organization and transport of PS in cells.
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Affiliation(s)
- Guillaume Lenoir
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell, Gif-sur-Yvette, France
| | - Juan Martín D'Ambrosio
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, Montpellier, France
| | - Thibaud Dieudonné
- Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic EMBL Partnership for Molecular Medicine, Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Alenka Čopič
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, Montpellier, France
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10
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The transport mechanism of P4 ATPase lipid flippases. Biochem J 2021; 477:3769-3790. [PMID: 33045059 DOI: 10.1042/bcj20200249] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 09/02/2020] [Accepted: 09/16/2020] [Indexed: 12/18/2022]
Abstract
P4 ATPase lipid flippases are ATP-driven transporters that translocate specific lipids from the exoplasmic to the cytosolic leaflet of biological membranes, thus establishing a lipid gradient between the two leaflets that is essential for many cellular processes. While substrate specificity, subcellular and tissue-specific expression, and physiological functions have been assigned to a number of these transporters in several organisms, the mechanism of lipid transport has been a topic of intense debate in the field. The recent publication of a series of structural models based on X-ray crystallography and cryo-EM studies has provided the first glimpse into how P4 ATPases have adapted the transport mechanism used by the cation-pumping family members to accommodate a substrate that is at least an order of magnitude larger than cations.
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11
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Mishra SK, Gao YG, Zou X, Stephenson DJ, Malinina L, Hinchcliffe EH, Chalfant CE, Brown RE. Emerging roles for human glycolipid transfer protein superfamily members in the regulation of autophagy, inflammation, and cell death. Prog Lipid Res 2020; 78:101031. [PMID: 32339554 DOI: 10.1016/j.plipres.2020.101031] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 02/27/2020] [Accepted: 02/27/2020] [Indexed: 12/14/2022]
Abstract
Glycolipid transfer proteins (GLTPs) were first identified over three decades ago as ~24kDa, soluble, amphitropic proteins that specifically accelerate the intermembrane transfer of glycolipids. Upon discovery that GLTPs use a unique, all-α-helical, two-layer 'sandwich' architecture (GLTP-fold) to bind glycosphingolipids (GSLs), a new protein superfamily was born. Structure/function studies have provided exquisite insights defining features responsible for lipid headgroup selectivity and hydrophobic 'pocket' adaptability for accommodating hydrocarbon chains of differing length and unsaturation. In humans, evolutionarily-modified GLTP-folds have been identified with altered sphingolipid specificity, e. g. ceramide-1-phosphate transfer protein (CPTP), phosphatidylinositol 4-phosphate adaptor protein-2 (FAPP2) which harbors a GLTP-domain and GLTPD2. Despite the wealth of structural data (>40 Protein Data Bank deposits), insights into the in vivo functional roles of GLTP superfamily members have emerged slowly. In this review, recent advances are presented and discussed implicating human GLTP superfamily members as important regulators of: i) pro-inflammatory eicosanoid production associated with Group-IV cytoplasmic phospholipase A2; ii) autophagy and inflammasome assembly that drive surveillance cell release of interleukin-1β and interleukin-18 inflammatory cytokines; iii) cell cycle arrest and necroptosis induction in certain colon cancer cell lines. The effects exerted by GLTP superfamily members appear linked to their ability to regulate sphingolipid homeostasis by acting in either transporter and/or sensor capacities. These timely findings are opening new avenues for future cross-disciplinary, translational medical research involving GLTP-fold proteins in human health and disease. Such avenues include targeted regulation of specific GLTP superfamily members to alter sphingolipid levels as a therapeutic means for combating viral infection, neurodegenerative conditions and circumventing chemo-resistance during cancer treatment.
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Affiliation(s)
- Shrawan K Mishra
- Hormel Institute, University of Minnesota, Austin, MN 55912, USA
| | - Yong-Guang Gao
- Hormel Institute, University of Minnesota, Austin, MN 55912, USA
| | - Xianqiong Zou
- Hormel Institute, University of Minnesota, Austin, MN 55912, USA
| | - Daniel J Stephenson
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University Medical Center, Richmond, VA 23298-0614, USA; Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL 33620, USA
| | - Lucy Malinina
- Hormel Institute, University of Minnesota, Austin, MN 55912, USA
| | | | - Charles E Chalfant
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL 33620, USA; Research Service, James A. Haley Veterans Hospital, Tampa, FL 33612, USA; The Moffitt Cancer Center, Tampa, FL 33620, USA
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12
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Tone T, Nakayama K, Takatsu H, Shin HW. ATPase reaction cycle of P4-ATPases affects their transport from the endoplasmic reticulum. FEBS Lett 2019; 594:412-423. [PMID: 31571211 DOI: 10.1002/1873-3468.13629] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 09/09/2019] [Accepted: 09/11/2019] [Indexed: 12/18/2022]
Abstract
P4-ATPases belonging to the P-type ATPase superfamily mediate active transport of phospholipids across cellular membranes. Most P4-ATPases, except ATP9A and ATP9B proteins, form heteromeric complexes with CDC50 proteins, which are required for transport of P4-ATPases from the endoplasmic reticulum (ER) to their final destinations. P-type ATPases form autophosphorylated intermediates during the ATPase reaction cycle. However, the association of the catalytic cycle of P4-ATPases with their transport from the ER and their cellular localization has not been studied. Here, we show that transport of ATP9 and ATP11 proteins as well as that of ATP10A from the ER depends on the ATPase catalytic cycle, suggesting that conformational changes in P4-ATPases during the catalytic cycle are crucial for their transport from the ER.
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Affiliation(s)
- Takuya Tone
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Japan
| | - Kazuhisa Nakayama
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Japan
| | - Hiroyuki Takatsu
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Japan
| | - Hye-Won Shin
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Japan
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