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Neumann J, Rose-Sperling D, Hellmich UA. Diverse relations between ABC transporters and lipids: An overview. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1859:605-618. [PMID: 27693344 DOI: 10.1016/j.bbamem.2016.09.023] [Citation(s) in RCA: 103] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 09/24/2016] [Accepted: 09/26/2016] [Indexed: 12/19/2022]
Abstract
It was first discovered in 1992 that P-glycoprotein (Pgp, ABCB1), an ATP binding cassette (ABC) transporter, can transport phospholipids such as phosphatidylcholine, -ethanolamine and -serine as well as glucosylceramide and glycosphingolipids. Subsequently, many other ABC transporters were identified to act as lipid transporters. For substrate transport by ABC transporters, typically a classic, alternating access model with an ATP-dependent conformational switch between a high and a low affinity substrate binding site is evoked. Transport of small hydrophilic substrates can easily be imagined this way, as the molecule can in principle enter and exit the transporter in the same orientation. Lipids on the other hand need to undergo a 180° degree turn as they translocate from one membrane leaflet to the other. Lipids and lipidated molecules are highly diverse, so there may be various ways how to achieve their flipping and flopping. Nonetheless, an increase in biophysical, biochemical and structural data is beginning to shed some light on specific aspects of lipid transport by ABC transporters. In addition, there is now abundant evidence that lipids affect ABC transporter conformation, dynamics as well as transport and ATPase activity in general. In this review, we will discuss different ways in which lipids and ABC transporters interact and how lipid translocation may be achieved with a focus on the techniques used to investigate these processes. This article is part of a Special Issue entitled: Lipid order/lipid defects and lipid-control of protein activity edited by Dirk Schneider.
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Affiliation(s)
- Jennifer Neumann
- Institute of Pharmacy and Biochemistry, Johannes Gutenberg University Mainz, Johann-Joachim-Becher-Weg 30, 55128 Mainz, Germany
| | - Dania Rose-Sperling
- Institute of Pharmacy and Biochemistry, Johannes Gutenberg University Mainz, Johann-Joachim-Becher-Weg 30, 55128 Mainz, Germany
| | - Ute A Hellmich
- Institute of Pharmacy and Biochemistry, Johannes Gutenberg University Mainz, Johann-Joachim-Becher-Weg 30, 55128 Mainz, Germany.
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52
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Directed evolution of a sphingomyelin flippase reveals mechanism of substrate backbone discrimination by a P4-ATPase. Proc Natl Acad Sci U S A 2016; 113:E4460-6. [PMID: 27432949 DOI: 10.1073/pnas.1525730113] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Phospholipid flippases in the type IV P-type ATPase (P4-ATPases) family establish membrane asymmetry and play critical roles in vesicular transport, cell polarity, signal transduction, and neurologic development. All characterized P4-ATPases flip glycerophospholipids across the bilayer to the cytosolic leaflet of the membrane, but how these enzymes distinguish glycerophospholipids from sphingolipids is not known. We used a directed evolution approach to examine the molecular mechanisms through which P4-ATPases discriminate substrate backbone. A mutagenesis screen in the yeast Saccharomyces cerevisiae has identified several gain-of-function mutations in the P4-ATPase Dnf1 that facilitate the transport of a novel lipid substrate, sphingomyelin. We found that a highly conserved asparagine (N220) in the first transmembrane segment is a key enforcer of glycerophospholipid selection, and specific substitutions at this site allow transport of sphingomyelin.
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53
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Takar M, Wu Y, Graham TR. The Essential Neo1 Protein from Budding Yeast Plays a Role in Establishing Aminophospholipid Asymmetry of the Plasma Membrane. J Biol Chem 2016; 291:15727-39. [PMID: 27235400 DOI: 10.1074/jbc.m115.686253] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Indexed: 11/06/2022] Open
Abstract
Eukaryotic organisms typically express multiple type IV P-type ATPases (P4-ATPases), which establish plasma membrane asymmetry by flipping specific phospholipids from the exofacial to the cytosolic leaflet. Saccharomyces cerevisiae, for example, expresses five P4-ATPases, including Neo1, Drs2, Dnf1, Dnf2, and Dnf3. Neo1 is thought to be a phospholipid flippase, although there is currently no experimental evidence that Neo1 catalyzes this activity or helps establish membrane asymmetry. Here, we use temperature-conditional alleles (neo1(ts)) to test whether Neo1 deficiency leads to loss of plasma membrane asymmetry. Wild-type (WT) yeast normally restrict most of the phosphatidylserine (PS) and phosphatidylethanolamine (PE) to the inner cytosolic leaflet of the plasma membrane. However, the neo1-1(ts) and neo1-2(ts) mutants display a loss of PS and PE asymmetry at permissive growth temperatures as measured by hypersensitivity to pore-forming toxins that target PS (papuamide A) or PE (duramycin) exposed in the extracellular leaflet. When shifted to a semi-permissive growth temperature, the neo1-1(ts) mutant became extremely hypersensitive to duramycin, although the sensitivity to papuamide A was unchanged, indicating preferential exposure of PE. This loss of asymmetry occurs despite the presence of other flippases that flip PS and/or PE. Even when overexpressed, Drs2 and Dnf1 were unable to correct the loss of asymmetry caused by neo1(ts) However, modest overexpression of Neo1 weakly suppressed loss of membrane asymmetry caused by drs2Δ with a more significant correction of PE asymmetry than PS. These results indicate that Neo1 plays an important role in establishing PS and PE plasma membrane asymmetry in budding yeast.
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Affiliation(s)
- Mehmet Takar
- From the Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235
| | - Yuantai Wu
- From the Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235
| | - Todd R Graham
- From the Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235
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54
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Botella C, Sautron E, Boudiere L, Michaud M, Dubots E, Yamaryo-Botté Y, Albrieux C, Marechal E, Block MA, Jouhet J. ALA10, a Phospholipid Flippase, Controls FAD2/FAD3 Desaturation of Phosphatidylcholine in the ER and Affects Chloroplast Lipid Composition in Arabidopsis thaliana. PLANT PHYSIOLOGY 2016; 170:1300-14. [PMID: 26620528 PMCID: PMC4775126 DOI: 10.1104/pp.15.01557] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 11/29/2015] [Indexed: 05/18/2023]
Abstract
The biogenesis of photosynthetic membranes relies on galactoglycerolipids, which are synthesized via pathways that are dispatched over several cell compartments. This membrane biogenesis requires both trafficking of lipid intermediates and a tight homeostatic regulation. In this work, we address the role of ALA10 (for aminophospholipid ATPase), a P4-type ATPase, in a process counteracting the monogalactosyldiacylglycerol (MGDG) shortage in Arabidopsis (Arabidopsis thaliana) leaves. ALA10 can interact with protein partners, ALIS1 (for ALA-interacting subunit1) or ALIS5, leading to differential endomembrane localizations of the interacting proteins, close to the plasma membrane with ALIS1 or to chloroplasts with ALIS5. ALA10 interacts also with FATTY ACID DESATURASE2 (FAD2), and modification of ALA10 expression affects phosphatidylcholine (PC) fatty acyl desaturation by disturbing the balance between FAD2 and FAD3 activities. Modulation of ALA10 expression downstream impacts the fatty acyl composition of chloroplast PC. ALA10 expression also enhances leaf growth and improves the MGDG-PC ratio, possibly through MGDG SYNTHASE1 (MGD1) activation by phosphatidic acid. The positive effect of ALA10 on leaf development is significant in conditions such as upon treatment of plants with Galvestine-1, an inhibitor of MGDG synthases, or when plants are grown at chilling temperature.
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Affiliation(s)
- César Botella
- Laboratoire de Physiologie Cellulaire et Végétale, Unité Mixte Recherche 5168, Centre National Recherche Scientifique, Université Grenoble-Alpes, Institut National de la Recherche Agronomique, Commissariat à l'Energie Atomique et Energies Alternatives, Institut de Recherches en Technologies et Sciences pour le Vivant, F-38054 Grenoble, France
| | - Emeline Sautron
- Laboratoire de Physiologie Cellulaire et Végétale, Unité Mixte Recherche 5168, Centre National Recherche Scientifique, Université Grenoble-Alpes, Institut National de la Recherche Agronomique, Commissariat à l'Energie Atomique et Energies Alternatives, Institut de Recherches en Technologies et Sciences pour le Vivant, F-38054 Grenoble, France
| | - Laurence Boudiere
- Laboratoire de Physiologie Cellulaire et Végétale, Unité Mixte Recherche 5168, Centre National Recherche Scientifique, Université Grenoble-Alpes, Institut National de la Recherche Agronomique, Commissariat à l'Energie Atomique et Energies Alternatives, Institut de Recherches en Technologies et Sciences pour le Vivant, F-38054 Grenoble, France
| | - Morgane Michaud
- Laboratoire de Physiologie Cellulaire et Végétale, Unité Mixte Recherche 5168, Centre National Recherche Scientifique, Université Grenoble-Alpes, Institut National de la Recherche Agronomique, Commissariat à l'Energie Atomique et Energies Alternatives, Institut de Recherches en Technologies et Sciences pour le Vivant, F-38054 Grenoble, France
| | - Emmanuelle Dubots
- Laboratoire de Physiologie Cellulaire et Végétale, Unité Mixte Recherche 5168, Centre National Recherche Scientifique, Université Grenoble-Alpes, Institut National de la Recherche Agronomique, Commissariat à l'Energie Atomique et Energies Alternatives, Institut de Recherches en Technologies et Sciences pour le Vivant, F-38054 Grenoble, France
| | - Yoshiki Yamaryo-Botté
- Laboratoire de Physiologie Cellulaire et Végétale, Unité Mixte Recherche 5168, Centre National Recherche Scientifique, Université Grenoble-Alpes, Institut National de la Recherche Agronomique, Commissariat à l'Energie Atomique et Energies Alternatives, Institut de Recherches en Technologies et Sciences pour le Vivant, F-38054 Grenoble, France
| | - Catherine Albrieux
- Laboratoire de Physiologie Cellulaire et Végétale, Unité Mixte Recherche 5168, Centre National Recherche Scientifique, Université Grenoble-Alpes, Institut National de la Recherche Agronomique, Commissariat à l'Energie Atomique et Energies Alternatives, Institut de Recherches en Technologies et Sciences pour le Vivant, F-38054 Grenoble, France
| | - Eric Marechal
- Laboratoire de Physiologie Cellulaire et Végétale, Unité Mixte Recherche 5168, Centre National Recherche Scientifique, Université Grenoble-Alpes, Institut National de la Recherche Agronomique, Commissariat à l'Energie Atomique et Energies Alternatives, Institut de Recherches en Technologies et Sciences pour le Vivant, F-38054 Grenoble, France
| | - Maryse A Block
- Laboratoire de Physiologie Cellulaire et Végétale, Unité Mixte Recherche 5168, Centre National Recherche Scientifique, Université Grenoble-Alpes, Institut National de la Recherche Agronomique, Commissariat à l'Energie Atomique et Energies Alternatives, Institut de Recherches en Technologies et Sciences pour le Vivant, F-38054 Grenoble, France
| | - Juliette Jouhet
- Laboratoire de Physiologie Cellulaire et Végétale, Unité Mixte Recherche 5168, Centre National Recherche Scientifique, Université Grenoble-Alpes, Institut National de la Recherche Agronomique, Commissariat à l'Energie Atomique et Energies Alternatives, Institut de Recherches en Technologies et Sciences pour le Vivant, F-38054 Grenoble, France
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55
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Andersen JP, Vestergaard AL, Mikkelsen SA, Mogensen LS, Chalat M, Molday RS. P4-ATPases as Phospholipid Flippases-Structure, Function, and Enigmas. Front Physiol 2016; 7:275. [PMID: 27458383 PMCID: PMC4937031 DOI: 10.3389/fphys.2016.00275] [Citation(s) in RCA: 208] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2016] [Accepted: 06/20/2016] [Indexed: 01/26/2023] Open
Abstract
P4-ATPases comprise a family of P-type ATPases that actively transport or flip phospholipids across cell membranes. This generates and maintains membrane lipid asymmetry, a property essential for a wide variety of cellular processes such as vesicle budding and trafficking, cell signaling, blood coagulation, apoptosis, bile and cholesterol homeostasis, and neuronal cell survival. Some P4-ATPases transport phosphatidylserine and phosphatidylethanolamine across the plasma membrane or intracellular membranes whereas other P4-ATPases are specific for phosphatidylcholine. The importance of P4-ATPases is highlighted by the finding that genetic defects in two P4-ATPases ATP8A2 and ATP8B1 are associated with severe human disorders. Recent studies have provided insight into how P4-ATPases translocate phospholipids across membranes. P4-ATPases form a phosphorylated intermediate at the aspartate of the P-type ATPase signature sequence, and dephosphorylation is activated by the lipid substrate being flipped from the exoplasmic to the cytoplasmic leaflet similar to the activation of dephosphorylation of Na(+)/K(+)-ATPase by exoplasmic K(+). How the phospholipid is translocated can be understood in terms of a peripheral hydrophobic gate pathway between transmembrane helices M1, M3, M4, and M6. This pathway, which partially overlaps with the suggested pathway for migration of Ca(2+) in the opposite direction in the Ca(2+)-ATPase, is wider than the latter, thereby accommodating the phospholipid head group. The head group is propelled along against its concentration gradient with the hydrocarbon chains projecting out into the lipid phase by movement of an isoleucine located at the position corresponding to an ion binding glutamate in the Ca(2+)- and Na(+)/K(+)-ATPases. Hence, the P4-ATPase mechanism is quite similar to the mechanism of these ion pumps, where the glutamate translocates the ions by moving like a pump rod. The accessory subunit CDC50 may be located in close association with the exoplasmic entrance of the suggested pathway, and possibly promotes the binding of the lipid substrate. This review focuses on properties of mammalian and yeast P4-ATPases for which most mechanistic insight is available. However, the structure, function and enigmas associated with mammalian and yeast P4-ATPases most likely extend to P4-ATPases of plants and other organisms.
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Affiliation(s)
| | | | | | | | - Madhavan Chalat
- Department of Biochemistry and Molecular Biology, University of British ColumbiaVancouver, BC, Canada
| | - Robert S. Molday
- Department of Biochemistry and Molecular Biology, University of British ColumbiaVancouver, BC, Canada
- *Correspondence: Robert S. Molday
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56
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Montigny C, Lyons J, Champeil P, Nissen P, Lenoir G. On the molecular mechanism of flippase- and scramblase-mediated phospholipid transport. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1861:767-783. [PMID: 26747647 DOI: 10.1016/j.bbalip.2015.12.020] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 12/20/2015] [Accepted: 12/28/2015] [Indexed: 11/20/2022]
Abstract
Phospholipid flippases are key regulators of transbilayer lipid asymmetry in eukaryotic cell membranes, critical to many trafficking and signaling pathways. P4-ATPases, in particular, are responsible for the uphill transport of phospholipids from the exoplasmic to the cytosolic leaflet of the plasma membrane, as well as membranes of the late secretory/endocytic pathways, thereby establishing transbilayer asymmetry. Recent studies combining cell biology and biochemical approaches have improved our understanding of the path taken by lipids through P4-ATPases. Additionally, identification of several protein families catalyzing phospholipid 'scrambling', i.e. disruption of phospholipid asymmetry through energy-independent bi-directional phospholipid transport, as well as the recent report of the structure of such a scramblase, opens the way to a deeper characterization of their mechanism of action. Here, we discuss the molecular nature of the mechanism by which lipids may 'flip' across membranes, with an emphasis on active lipid transport catalyzed by P4-ATPases. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon.
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Affiliation(s)
- Cédric Montigny
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Joseph Lyons
- DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, and PUMPkin, Danish National Research Foundation, Aarhus University, Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, 8000 Aarhus C, Denmark
| | - Philippe Champeil
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Poul Nissen
- DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, and PUMPkin, Danish National Research Foundation, Aarhus University, Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, 8000 Aarhus C, Denmark
| | - Guillaume Lenoir
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France.
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57
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Specific mutations in mammalian P4-ATPase ATP8A2 catalytic subunit entail differential glycosylation of the accessory CDC50A subunit. FEBS Lett 2015; 589:3908-14. [PMID: 26592152 DOI: 10.1016/j.febslet.2015.11.031] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 11/16/2015] [Accepted: 11/16/2015] [Indexed: 12/21/2022]
Abstract
P4-ATPases, or flippases, translocate phospholipids between the two leaflets of eukaryotic biological membranes. They are essential to the physiologically crucial phospholipid asymmetry and involved in severe diseases, but their molecular structure and mechanism are still unresolved. Here, we show that in an extensive mutational alanine screening of the mammalian flippase ATP8A2 catalytic subunit, five mutations stand out by leading to reduced glycosylation of the accessory subunit CDC50A. These mutations may disturb the interaction between the subunits.
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58
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Hankins HM, Sere YY, Diab NS, Menon AK, Graham TR. Phosphatidylserine translocation at the yeast trans-Golgi network regulates protein sorting into exocytic vesicles. Mol Biol Cell 2015; 26:4674-85. [PMID: 26466678 PMCID: PMC4678023 DOI: 10.1091/mbc.e15-07-0487] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 10/06/2015] [Indexed: 11/16/2022] Open
Abstract
Protein sorting into exocytic vesicles at the yeast trans-Golgi network is believed to be mediated by their coalescence with specific lipids, but how this event is regulated is poorly understood. It is shown that phosphatidylserine flip by Drs2 is required for efficient sorting of the plasma membrane proteins Pma1 and Can1 into exocytic vesicles. Sorting of plasma membrane proteins into exocytic vesicles at the yeast trans-Golgi network (TGN) is believed to be mediated by their coalescence with specific lipids, but how these membrane-remodeling events are regulated is poorly understood. Here we show that the ATP-dependent phospholipid flippase Drs2 is required for efficient segregation of cargo into exocytic vesicles. The plasma membrane proteins Pma1 and Can1 are missorted from the TGN to the vacuole in drs2∆ cells. We also used a combination of flippase mutants that either gain or lose the ability to flip phosphatidylserine (PS) to determine that PS flip by Drs2 is its critical function in this sorting event. The primary role of PS flip at the TGN appears to be to control the oxysterol-binding protein homologue Kes1/Osh4 and regulate ergosterol subcellular distribution. Deletion of KES1 suppresses plasma membrane–missorting defects and the accumulation of intracellular ergosterol in drs2 mutants. We propose that PS flip is part of a homeostatic mechanism that controls sterol loading and lateral segregation of protein and lipid domains at the TGN.
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Affiliation(s)
- Hannah M Hankins
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235
| | - Yves Y Sere
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065
| | - Nicholas S Diab
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235
| | - Anant K Menon
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065
| | - Todd R Graham
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235
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59
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Segawa K, Nagata S. An Apoptotic 'Eat Me' Signal: Phosphatidylserine Exposure. Trends Cell Biol 2015; 25:639-650. [PMID: 26437594 DOI: 10.1016/j.tcb.2015.08.003] [Citation(s) in RCA: 491] [Impact Index Per Article: 54.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 08/08/2015] [Accepted: 08/17/2015] [Indexed: 12/19/2022]
Abstract
Apoptosis and the clearance of apoptotic cells are essential processes in animal development and homeostasis. For apoptotic cells to be cleared, they must display an 'eat me' signal, most likely phosphatidylserine (PtdSer) exposure, which prompts phagocytes to engulf the cells. PtdSer, which is recognized by several different systems, is normally confined to the cytoplasmic leaflet of the plasma membrane by a 'flippase'; apoptosis activates a 'scramblase' that quickly exposes PtdSer on the cell surface. The molecules that flip and scramble phospholipids at the plasma membrane have recently been identified. Here we discuss recent findings regarding the molecular mechanisms of apoptotic PtdSer exposure and the clearance of apoptotic cells.
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Affiliation(s)
- Katsumori Segawa
- Laboratory of Biochemistry and Immunology, WPI Immunology Frontier Research Center, Osaka University, 3-1 Yamada-oka, Suita 565-0871, Japan
| | - Shigekazu Nagata
- Laboratory of Biochemistry and Immunology, WPI Immunology Frontier Research Center, Osaka University, 3-1 Yamada-oka, Suita 565-0871, Japan.
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60
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Korneenko TV, Pestov NB, Okkelman IA, Modyanov NN, Shakhparonov MI. [P4-ATP-ase Atp8b1/FIC1: structural properties and (patho)physiological functions]. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2015; 41:3-12. [PMID: 26050466 DOI: 10.1134/s1068162015010070] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
P4-ATP-ases comprise an interesting family among P-type ATP-ases, since they are thought to play a major role in the transfer of phospholipids such as phosphatydylserine from the outer leaflet to the inner leaflet. Isoforms of P4-ATP-ases are partially interchangeable but peculiarities of tissue-specific expression of their genes, intracellular localization of proteins, as well as regulatory pathways lead to the fact that, on the organismal level, serious pathologies may develop in the presence of structural abnormalities in certain isoforms. Among P4-ATP-ases a special place is occupied by ATP8B1, for which several mutations are known that lead to serious hereditary diseases: two forms of congenital cholestasis (PFIC1 or Byler disease and benign recurrent intrahepatic cholestasis) with extraliver symptoms such as sensorineural hearing loss. The physiological function of the Atp8b1/FIC1 protein is known in general outline: it is responsible for transport of certain phospholipids (phosphatydylserine, cardiolipin) for the outer monolayer of the plasma membrane to the inner one. It is well known that perturbation of membrane asymmetry, caused by the lack of Atp8B1 activity, leads to death of hairy cells of the inner ear, dysfunction of bile acid transport in liver-cells that causes cirrhosis. It is also probable that insufficient activity of Atp8b1/FIC1 increases susceptibility to bacterial pneumonia.Regulatory pathways of Atp8b1/FIC1 activity in vivo remain to be insufficiently studied and this opens novel perspectives for research in this field that may allow better understanding of molecular processes behind the development of certain pathologies and to reveal novel therapeutical targets.
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61
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Yu K, Whitlock JM, Lee K, Ortlund EA, Yuan Cui Y, Hartzell HC. Identification of a lipid scrambling domain in ANO6/TMEM16F. eLife 2015; 4:e06901. [PMID: 26057829 PMCID: PMC4477620 DOI: 10.7554/elife.06901] [Citation(s) in RCA: 138] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Accepted: 06/08/2015] [Indexed: 12/22/2022] Open
Abstract
Phospholipid scrambling (PLS) is a ubiquitous cellular mechanism involving the regulated bidirectional transport of phospholipids down their concentration gradient between membrane leaflets. ANO6/TMEM16F has been shown to be essential for Ca(2+)-dependent PLS, but controversy surrounds whether ANO6 is a phospholipid scramblase or an ion channel like other ANO/TMEM16 family members. Combining patch clamp recording with measurement of PLS, we show that ANO6 elicits robust Ca(2+)-dependent PLS coinciding with ionic currents that are explained by ionic leak during phospholipid translocation. By analyzing ANO1-ANO6 chimeric proteins, we identify a domain in ANO6 necessary for PLS and sufficient to confer this function on ANO1, which normally does not scramble. Homology modeling shows that the scramblase domain forms an unusual hydrophilic cleft that faces the lipid bilayer and may function to facilitate translocation of phospholipid between membrane leaflets. These findings provide a mechanistic framework for understanding PLS and how ANO6 functions in this process.
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Affiliation(s)
- Kuai Yu
- Department of Cell Biology, Emory University School of Medicine, Atlanta, United States
| | - Jarred M Whitlock
- Department of Cell Biology, Emory University School of Medicine, Atlanta, United States
| | - Kyleen Lee
- Department of Cell Biology, Emory University School of Medicine, Atlanta, United States
| | - Eric A Ortlund
- Department of Cell Biology, Emory University School of Medicine, Atlanta, United States
- Department of Biochemistry, Emory University School of Medicine, Atlanta, United States
| | - Yuan Yuan Cui
- Department of Cell Biology, Emory University School of Medicine, Atlanta, United States
| | - H Criss Hartzell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, United States
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62
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Substrate trajectory through phospholipid-transporting P4-ATPases. Biochem Soc Trans 2015; 42:1367-71. [PMID: 25233416 DOI: 10.1042/bst20140137] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A difference in the lipid composition between the two leaflets of the same membrane is a relatively simple instance of lipid compositional heterogeneity. The large activation energy barrier for transbilayer movement for some (but not all) membrane lipids creates a regime governed by active transport processes. An early step in eukaryote evolution was the development of a capacity for generating transbilayer compositional heterogeneity far from equilibrium by directly tapping energy from the ATP pool. The mechanism of the P-type ATPases that create lipid asymmetry is well understood in terms of ATP hydrolysis, but the trajectory taken by the phospholipid substrate through the enzyme is a matter of current active research. There are currently three different models for this trajectory, all with support by mutation/activity measurements and analogies with known atomic structures.
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63
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Naito T, Takatsu H, Miyano R, Takada N, Nakayama K, Shin HW. Phospholipid Flippase ATP10A Translocates Phosphatidylcholine and Is Involved in Plasma Membrane Dynamics. J Biol Chem 2015; 290:15004-17. [PMID: 25947375 DOI: 10.1074/jbc.m115.655191] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2015] [Indexed: 11/06/2022] Open
Abstract
We showed previously that ATP11A and ATP11C have flippase activity toward aminophospholipids (phosphatidylserine (PS) and phosphatidylethanolamine (PE)) and ATP8B1 and that ATP8B2 have flippase activity toward phosphatidylcholine (PC) (Takatsu, H., Tanaka, G., Segawa, K., Suzuki, J., Nagata, S., Nakayama, K., and Shin, H. W. (2014) J. Biol. Chem. 289, 33543-33556). Here, we show that the localization of class 5 P4-ATPases to the plasma membrane (ATP10A and ATP10D) and late endosomes (ATP10B) requires an interaction with CDC50A. Moreover, exogenous expression of ATP10A, but not its ATPase-deficient mutant ATP10A(E203Q), dramatically increased PC flipping but not flipping of PS or PE. Depletion of CDC50A caused ATP10A to be retained at the endoplasmic reticulum instead of being delivered to the plasma membrane and abrogated the increased PC flipping activity observed by expression of ATP10A. These results demonstrate that ATP10A is delivered to the plasma membrane via its interaction with CDC50A and, specifically, flips PC at the plasma membrane. Importantly, expression of ATP10A, but not ATP10A(E203Q), dramatically altered the cell shape and decreased cell size. In addition, expression of ATP10A, but not ATP10A(E203Q), delayed cell adhesion and cell spreading onto the extracellular matrix. These results suggest that enhanced PC flipping activity due to exogenous ATP10A expression alters the lipid composition at the plasma membrane, which may in turn cause a delay in cell spreading and a change in cell morphology.
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Affiliation(s)
| | | | | | - Naoto Takada
- the Faculty of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
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Panatala R, Hennrich H, Holthuis JCM. Inner workings and biological impact of phospholipid flippases. J Cell Sci 2015; 128:2021-32. [PMID: 25918123 DOI: 10.1242/jcs.102715] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The plasma membrane, trans-Golgi network and endosomal system of eukaryotic cells are populated with flippases that hydrolyze ATP to help establish asymmetric phospholipid distributions across the bilayer. Upholding phospholipid asymmetry is vital to a host of cellular processes, including membrane homeostasis, vesicle biogenesis, cell signaling, morphogenesis and migration. Consequently, defining the identity of flippases and their biological impact has been the subject of intense investigations. Recent work has revealed a remarkable degree of kinship between flippases and cation pumps. In this Commentary, we review emerging insights into how flippases work, how their activity is controlled according to cellular demands, and how disrupting flippase activity causes system failure of membrane function, culminating in membrane trafficking defects, aberrant signaling and disease.
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Affiliation(s)
- Radhakrishnan Panatala
- Department of Membrane Enzymology, Bijvoet Center and Institute of Biomembranes, Utrecht University, 3584 Utrecht, The Netherlands Molecular Cell Biology Division, University of Osnabrück, 49076 Osnabrück, Germany
| | - Hanka Hennrich
- Department of Membrane Enzymology, Bijvoet Center and Institute of Biomembranes, Utrecht University, 3584 Utrecht, The Netherlands
| | - Joost C M Holthuis
- Department of Membrane Enzymology, Bijvoet Center and Institute of Biomembranes, Utrecht University, 3584 Utrecht, The Netherlands Molecular Cell Biology Division, University of Osnabrück, 49076 Osnabrück, Germany
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65
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P4-ATPases: lipid flippases in cell membranes. Pflugers Arch 2015; 466:1227-40. [PMID: 24077738 PMCID: PMC4062807 DOI: 10.1007/s00424-013-1363-4] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Revised: 09/11/2013] [Accepted: 09/11/2013] [Indexed: 12/13/2022]
Abstract
Cellular membranes, notably eukaryotic plasma membranes, are equipped with special proteins that actively translocate lipids from one leaflet to the other and thereby help generate membrane lipid asymmetry. Among these ATP-driven transporters, the P4 subfamily of P-type ATPases (P4-ATPases) comprises lipid flippases that catalyze the translocation of phospholipids from the exoplasmic to the cytosolic leaflet of cell membranes. While initially characterized as aminophospholipid translocases, recent studies of individual P4-ATPase family members from fungi, plants, and animals show that P4-ATPases differ in their substrate specificities and mediate transport of a broader range of lipid substrates, including lysophospholipids and synthetic alkylphospholipids. At the same time, the cellular processes known to be directly or indirectly affected by this class of transporters have expanded to include the regulation of membrane traffic, cytoskeletal dynamics, cell division, lipid metabolism, and lipid signaling. In this review, we will summarize the basic features of P4-ATPases and the physiological implications of their lipid transport activity in the cell.
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McDowell SC, López-Marqués RL, Cohen T, Brown E, Rosenberg A, Palmgren MG, Harper JF. Loss of the Arabidopsis thaliana P4-ATPases ALA6 and ALA7 impairs pollen fitness and alters the pollen tube plasma membrane. FRONTIERS IN PLANT SCIENCE 2015; 6:197. [PMID: 25954280 PMCID: PMC4404812 DOI: 10.3389/fpls.2015.00197] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 03/12/2015] [Indexed: 05/19/2023]
Abstract
Members of the P4 subfamily of P-type ATPases are thought to create and maintain lipid asymmetry in biological membranes by flipping specific lipids between membrane leaflets. In Arabidopsis, 7 of the 12 Aminophospholipid ATPase (ALA) family members are expressed in pollen. Here we show that double knockout of ALA6 and ALA7 (ala6/7) results in siliques with a ~2-fold reduction in seed set with a high frequency of empty seed positions near the bottom. Seed set was reduced to near zero when plants were grown under a hot/cold temperature stress. Reciprocal crosses indicate that the ala6/7 reproductive deficiencies are due to a defect related to pollen transmission. In-vitro growth assays provide evidence that ala6/7 pollen tubes are short and slow, with ~2-fold reductions in both maximal growth rate and overall length relative to wild-type. Outcrosses show that when ala6/7 pollen are in competition with wild-type pollen, they have a near 0% success rate in fertilizing ovules near the bottom of the pistil, consistent with ala6/7 pollen having short and slow growth defects. The ala6/7 phenotypes were rescued by the expression of either an ALA6-YFP or GFP-ALA6 fusion protein, which showed localization to both the plasma membrane and highly-mobile endomembrane structures. A mass spectrometry analysis of mature pollen grains revealed significant differences between ala6/7 and wild-type, both in the relative abundance of lipid classes and in the average number of double bonds present in acyl side chains. A change in the properties of the ala6/7 plasma membrane was also indicated by a ~10-fold reduction of labeling by lipophilic FM-dyes relative to wild-type. Together, these results indicate that ALA6 and ALA7 provide redundant activities that function to directly or indirectly change the distribution and abundance of lipids in pollen, and support a model in which ALA6 and ALA7 are critical for pollen fitness under normal and temperature-stress conditions.
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Affiliation(s)
- Stephen C. McDowell
- Department of Biochemistry and Molecular Biology, University of NevadaReno, NV, USA
| | - Rosa L. López-Marqués
- Centre for Membrane Pumps in Cells and Disease, Department of Plant and Environmental Sciences, University of Copenhagen, Danish National Research FoundationFrederiksberg, Denmark
| | - Taylor Cohen
- Department of Biochemistry and Molecular Biology, University of NevadaReno, NV, USA
| | - Elizabeth Brown
- Department of Biochemistry and Molecular Biology, University of NevadaReno, NV, USA
| | - Alexa Rosenberg
- Department of Biochemistry and Molecular Biology, University of NevadaReno, NV, USA
| | - Michael G. Palmgren
- Centre for Membrane Pumps in Cells and Disease, Department of Plant and Environmental Sciences, University of Copenhagen, Danish National Research FoundationFrederiksberg, Denmark
| | - Jeffrey F. Harper
- Department of Biochemistry and Molecular Biology, University of NevadaReno, NV, USA
- *Correspondence: Jeffrey F. Harper, Department of Biochemistry and Molecular Biology, University of Nevada, 1664 N. Virginia St - MS330, Reno, NV 89557, USA
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Azouaoui H, Montigny C, Ash MR, Fijalkowski F, Jacquot A, Grønberg C, López-Marqués RL, Palmgren MG, Garrigos M, le Maire M, Decottignies P, Gourdon P, Nissen P, Champeil P, Lenoir G. A high-yield co-expression system for the purification of an intact Drs2p-Cdc50p lipid flippase complex, critically dependent on and stabilized by phosphatidylinositol-4-phosphate. PLoS One 2014; 9:e112176. [PMID: 25393116 PMCID: PMC4230938 DOI: 10.1371/journal.pone.0112176] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 10/13/2014] [Indexed: 01/01/2023] Open
Abstract
P-type ATPases from the P4 subfamily (P4-ATPases) are energy-dependent transporters, which are thought to establish lipid asymmetry in eukaryotic cell membranes. Together with their Cdc50 accessory subunits, P4-ATPases couple ATP hydrolysis to lipid transport from the exoplasmic to the cytoplasmic leaflet of plasma membranes, late Golgi membranes, and endosomes. To gain insights into the structure and function of these important membrane pumps, robust protocols for expression and purification are required. In this report, we present a procedure for high-yield co-expression of a yeast flippase, the Drs2p-Cdc50p complex. After recovery of yeast membranes expressing both proteins, efficient purification was achieved in a single step by affinity chromatography on streptavidin beads, yielding ∼1–2 mg purified Drs2p-Cdc50p complex per liter of culture. Importantly, the procedure enabled us to recover a fraction that mainly contained a 1∶1 complex, which was assessed by size-exclusion chromatography and mass spectrometry. The functional properties of the purified complex were examined, including the dependence of its catalytic cycle on specific lipids. The dephosphorylation rate was stimulated in the simultaneous presence of the transported substrate, phosphatidylserine (PS), and the regulatory lipid phosphatidylinositol-4-phosphate (PI4P), a phosphoinositide that plays critical roles in membrane trafficking events from the trans-Golgi network (TGN). Likewise, overall ATP hydrolysis by the complex was critically dependent on the simultaneous presence of PI4P and PS. We also identified a prominent role for PI4P in stabilization of the Drs2p-Cdc50p complex towards temperature- or C12E8-induced irreversible inactivation. These results indicate that the Drs2p-Cdc50p complex remains functional after affinity purification and that PI4P as a cofactor tightly controls its stability and catalytic activity. This work offers appealing perspectives for detailed structural and functional characterization of the Drs2p-Cdc50p lipid transport mechanism.
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Affiliation(s)
- Hassina Azouaoui
- Univ Paris-Sud, UMR 8221, Orsay, France
- CEA, iBiTec-S (Institut de Biologie et de Technologies de Saclay), SBSM (Service de Bioénergétique, Biologie Structurale et Mécanismes), Laboratoire des Protéines Membranaires, Gif-sur-Yvette, France
- CNRS, UMR 8221, Gif-sur-Yvette, France
| | - Cédric Montigny
- Univ Paris-Sud, UMR 8221, Orsay, France
- CEA, iBiTec-S (Institut de Biologie et de Technologies de Saclay), SBSM (Service de Bioénergétique, Biologie Structurale et Mécanismes), Laboratoire des Protéines Membranaires, Gif-sur-Yvette, France
- CNRS, UMR 8221, Gif-sur-Yvette, France
| | - Miriam-Rose Ash
- Centre for Membrane Pumps in Cells and Disease – PUMPKIN, Danish National Research Foundation, Aarhus, Denmark
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Frank Fijalkowski
- Centre for Membrane Pumps in Cells and Disease – PUMPKIN, Danish National Research Foundation, Aarhus, Denmark
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Aurore Jacquot
- Univ Paris-Sud, UMR 8221, Orsay, France
- CEA, iBiTec-S (Institut de Biologie et de Technologies de Saclay), SBSM (Service de Bioénergétique, Biologie Structurale et Mécanismes), Laboratoire des Protéines Membranaires, Gif-sur-Yvette, France
- CNRS, UMR 8221, Gif-sur-Yvette, France
| | - Christina Grønberg
- Centre for Membrane Pumps in Cells and Disease – PUMPKIN, Danish National Research Foundation, Aarhus, Denmark
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Rosa L. López-Marqués
- Centre for Membrane Pumps in Cells and Disease – PUMPKIN, Danish National Research Foundation, Aarhus, Denmark
- Department of Plant and Environmental Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Michael G. Palmgren
- Centre for Membrane Pumps in Cells and Disease – PUMPKIN, Danish National Research Foundation, Aarhus, Denmark
- Department of Plant and Environmental Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Manuel Garrigos
- Univ Paris-Sud, UMR 8221, Orsay, France
- CEA, iBiTec-S (Institut de Biologie et de Technologies de Saclay), SBSM (Service de Bioénergétique, Biologie Structurale et Mécanismes), Laboratoire des Protéines Membranaires, Gif-sur-Yvette, France
- CNRS, UMR 8221, Gif-sur-Yvette, France
| | - Marc le Maire
- Univ Paris-Sud, UMR 8221, Orsay, France
- CEA, iBiTec-S (Institut de Biologie et de Technologies de Saclay), SBSM (Service de Bioénergétique, Biologie Structurale et Mécanismes), Laboratoire des Protéines Membranaires, Gif-sur-Yvette, France
- CNRS, UMR 8221, Gif-sur-Yvette, France
| | - Paulette Decottignies
- CNRS, Institut de Biochimie et Biophysique Moléculaire et Cellulaire, UMR 8619, Orsay, France
- Univ Paris-Sud, Orsay, France
| | - Pontus Gourdon
- Centre for Membrane Pumps in Cells and Disease – PUMPKIN, Danish National Research Foundation, Aarhus, Denmark
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Poul Nissen
- Centre for Membrane Pumps in Cells and Disease – PUMPKIN, Danish National Research Foundation, Aarhus, Denmark
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Philippe Champeil
- Univ Paris-Sud, UMR 8221, Orsay, France
- CEA, iBiTec-S (Institut de Biologie et de Technologies de Saclay), SBSM (Service de Bioénergétique, Biologie Structurale et Mécanismes), Laboratoire des Protéines Membranaires, Gif-sur-Yvette, France
- CNRS, UMR 8221, Gif-sur-Yvette, France
| | - Guillaume Lenoir
- Univ Paris-Sud, UMR 8221, Orsay, France
- CEA, iBiTec-S (Institut de Biologie et de Technologies de Saclay), SBSM (Service de Bioénergétique, Biologie Structurale et Mécanismes), Laboratoire des Protéines Membranaires, Gif-sur-Yvette, France
- CNRS, UMR 8221, Gif-sur-Yvette, France
- * E-mail:
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Hankins HM, Baldridge RD, Xu P, Graham TR. Role of flippases, scramblases and transfer proteins in phosphatidylserine subcellular distribution. Traffic 2014; 16:35-47. [PMID: 25284293 DOI: 10.1111/tra.12233] [Citation(s) in RCA: 194] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 09/29/2014] [Accepted: 09/30/2014] [Indexed: 12/11/2022]
Abstract
It is well known that lipids are heterogeneously distributed throughout the cell. Most lipid species are synthesized in the endoplasmic reticulum (ER) and then distributed to different cellular locations in order to create the distinct membrane compositions observed in eukaryotes. However, the mechanisms by which specific lipid species are trafficked to and maintained in specific areas of the cell are poorly understood and constitute an active area of research. Of particular interest is the distribution of phosphatidylserine (PS), an anionic lipid that is enriched in the cytosolic leaflet of the plasma membrane. PS transport occurs by both vesicular and non-vesicular routes, with members of the oxysterol-binding protein family (Osh6 and Osh7) recently implicated in the latter route. In addition, the flippase activity of P4-ATPases helps build PS membrane asymmetry by preferentially translocating PS to the cytosolic leaflet. This asymmetric PS distribution can be used as a signaling device by the regulated activation of scramblases, which rapidly expose PS on the extracellular leaflet and play important roles in blood clotting and apoptosis. This review will discuss recent advances made in the study of phospholipid flippases, scramblases and PS-specific lipid transfer proteins, as well as how these proteins contribute to subcellular PS distribution.
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Affiliation(s)
- Hannah M Hankins
- Department of Biological Sciences, Vanderbilt University Medical Center, Nashville, TN, 37235, USA
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Aberuyi N, Rahgozar S, Moafi A. The role of ATP-binding cassette transporter A2 in childhood acute lymphoblastic leukemia multidrug resistance. IRANIAN JOURNAL OF PEDIATRIC HEMATOLOGY AND ONCOLOGY 2014; 4:118-26. [PMID: 25254091 PMCID: PMC4173032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 08/07/2014] [Indexed: 11/17/2022]
Abstract
Acute lymphoblastic leukemia (ALL) is one of the most prevalent hematologic malignancies in children. Although the cure rate of ALL has improved over the past decades, the most important reason for ALL treatment failure is multidrug resistance (MDR) phenomenon. The current study aims to explain the mechanisms involved in multidrug resistance of childhood ALL, and introduces ATP-binding cassette transporterA2 (ABCA2) as an ABC transporter gene which may have a high impact on MDR. Benefiting from articles published inreputable journals from1994 to date and experiments newly performed by our group, a comprehensive review is written about ABCA2 and its role in MDR regarding childhood ALL. ABCA2 transports drugs from the cytoplasm into the lysosomal compartment, where they may become degraded and exported from the cell. The aforementioned mechanism may contribute to MDR. It has been reported that ABCA2 may induce resistance to mitoxantrone, estrogen derivatives and estramustine. It is resistant to the aforementioned compounds. Furthermore, the overexpression ofABCA2 in methotrexate, vinblastine and/or doxorubicin treated Jurkat cells are observed in several publications. The recent study of our group showsthatthe overexpression ofABCA2 gene in children with ALL increases the risk of MDR by 15 times. ABCA2 is the second identified member of the ABCA; ABC transporters' subfamily. ABCA2 gene expression profile is suggested to be an unfavorable prognostic factor in ALL treatment. Better understanding of the MDR mechanisms and the factors involved may improve the therapeutic outcome of ALL by modifying the treatment protocols.
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Affiliation(s)
- N Aberuyi
- Division of Cell and Molecular Biology, Department of Biology, Faculty of Science, University of Isfahan, Iran
| | - S Rahgozar
- Division of Cell and Molecular Biology, Department of Biology, Faculty of Science, University of Isfahan, Iran
| | - A Moafi
- Department of Paediatric-Oncology, SayedolShohada Hospital, Isfahan University of Medical Sciences, Isfahan, Iran
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70
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Hurlock AK, Roston RL, Wang K, Benning C. Lipid trafficking in plant cells. Traffic 2014; 15:915-32. [PMID: 24931800 DOI: 10.1111/tra.12187] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 06/12/2014] [Accepted: 06/12/2014] [Indexed: 12/29/2022]
Abstract
Plant cells contain unique organelles such as chloroplasts with an extensive photosynthetic membrane. In addition, specialized epidermal cells produce an extracellular cuticle composed primarily of lipids, and storage cells accumulate large amounts of storage lipids. As lipid assembly is associated only with discrete membranes or organelles, there is a need for extensive lipid trafficking within plant cells, more so in specialized cells and sometimes also in response to changing environmental conditions such as phosphate deprivation. Because of the complexity of plant lipid metabolism and the inherent recalcitrance of membrane lipid transporters, the mechanisms of lipid transport within plant cells are not yet fully understood. Recently, several new proteins have been implicated in different aspects of plant lipid trafficking. While these proteins provide only first insights into limited aspects of lipid transport phenomena in plant cells, they represent exciting opportunities for further studies.
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Affiliation(s)
- Anna K Hurlock
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA; Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA
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71
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van Veen S, Sørensen DM, Holemans T, Holen HW, Palmgren MG, Vangheluwe P. Cellular function and pathological role of ATP13A2 and related P-type transport ATPases in Parkinson's disease and other neurological disorders. Front Mol Neurosci 2014; 7:48. [PMID: 24904274 PMCID: PMC4033846 DOI: 10.3389/fnmol.2014.00048] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 05/05/2014] [Indexed: 12/14/2022] Open
Abstract
Mutations in ATP13A2 lead to Kufor-Rakeb syndrome, a parkinsonism with dementia. ATP13A2 belongs to the P-type transport ATPases, a large family of primary active transporters that exert vital cellular functions. However, the cellular function and transported substrate of ATP13A2 remain unknown. To discuss the role of ATP13A2 in neurodegeneration, we first provide a short description of the architecture and transport mechanism of P-type transport ATPases. Then, we briefly highlight key P-type ATPases involved in neuronal disorders such as the copper transporters ATP7A (Menkes disease), ATP7B (Wilson disease), the Na(+)/K(+)-ATPases ATP1A2 (familial hemiplegic migraine) and ATP1A3 (rapid-onset dystonia parkinsonism). Finally, we review the recent literature of ATP13A2 and discuss ATP13A2's putative cellular function in the light of what is known concerning the functions of other, better-studied P-type ATPases. We critically review the available data concerning the role of ATP13A2 in heavy metal transport and propose a possible alternative hypothesis that ATP13A2 might be a flippase. As a flippase, ATP13A2 may transport an organic molecule, such as a lipid or a peptide, from one membrane leaflet to the other. A flippase might control local lipid dynamics during vesicle formation and membrane fusion events.
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Affiliation(s)
- Sarah van Veen
- Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, KU Leuven Leuven, Belgium
| | - Danny M Sørensen
- Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, KU Leuven Leuven, Belgium
| | - Tine Holemans
- Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, KU Leuven Leuven, Belgium
| | - Henrik W Holen
- Department of Plant and Environmental Sciences, Centre for Membrane Pumps in Cells and Disease - PUMPkin, University of Copenhagen Frederiksberg, Denmark
| | - Michael G Palmgren
- Department of Plant and Environmental Sciences, Centre for Membrane Pumps in Cells and Disease - PUMPkin, University of Copenhagen Frederiksberg, Denmark
| | - Peter Vangheluwe
- Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, KU Leuven Leuven, Belgium
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Structure and mechanism of ATP-dependent phospholipid transporters. Biochim Biophys Acta Gen Subj 2014; 1850:461-75. [PMID: 24746984 DOI: 10.1016/j.bbagen.2014.04.008] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2014] [Revised: 04/04/2014] [Accepted: 04/07/2014] [Indexed: 01/09/2023]
Abstract
BACKGROUND ATP-binding cassette (ABC) transporters and P4-ATPases are two large and seemingly unrelated families of primary active pumps involved in moving phospholipids from one leaflet of a biological membrane to the other. SCOPE OF REVIEW This review aims to identify common mechanistic features in the way phospholipid flipping is carried out by two evolutionarily unrelated families of transporters. MAJOR CONCLUSIONS Both protein families hydrolyze ATP, although they employ different mechanisms to use it, and have a comparable size with twelve transmembrane segments in the functional unit. Further, despite differences in overall architecture, both appear to operate by an alternating access mechanism and during transport they might allow access of phospholipids to the internal part of the transmembrane domain. The latter feature is obvious for ABC transporters, but phospholipids and other hydrophobic molecules have also been found embedded in P-type ATPase crystal structures. Taken together, in two diverse groups of pumps, nature appears to have evolved quite similar ways of flipping phospholipids. GENERAL SIGNIFICANCE Our understanding of the structural basis for phospholipid flipping is still limited but it seems plausible that a general mechanism for phospholipid flipping exists in nature. This article is part of a Special Issue entitled Structural biochemistry and biophysics of membrane proteins.
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73
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Critical roles of isoleucine-364 and adjacent residues in a hydrophobic gate control of phospholipid transport by the mammalian P4-ATPase ATP8A2. Proc Natl Acad Sci U S A 2014; 111:E1334-43. [PMID: 24706822 DOI: 10.1073/pnas.1321165111] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
P4-ATPases (flippases) translocate specific phospholipids such as phosphatidylserine from the exoplasmic leaflet of the cell membrane to the cytosolic leaflet, upholding an essential membrane asymmetry. The mechanism of flipping this giant substrate has remained an enigma. We have investigated the importance of amino acid residues in transmembrane segment M4 of mammalian P4-ATPase ATP8A2 by mutagenesis. In the related ion pumps Na(+),K(+)-ATPase and Ca(2+)-ATPase, M4 moves during the enzyme cycle, carrying along the ion bound to a glutamate. In ATP8A2, the corresponding residue is an isoleucine, which recently was found mutated in patients with cerebellar ataxia, mental retardation, and dysequilibrium syndrome. Our analyses of the lipid substrate concentration dependence of the overall and partial reactions of the enzyme cycle in mutants indicate that, during the transport across the membrane, the phosphatidylserine head group passes near isoleucine-364 (I364) and that I364 is critical to the release of the transported lipid into the cytosolic leaflet. Another M4 residue, N359, is involved in recognition of the lipid substrate on the exoplasmic side. Our functional studies are supported by structural homology modeling and molecular dynamics simulations, suggesting that I364 and adjacent hydrophobic residues function as a hydrophobic gate that separates the entry and exit sites of the lipid and directs sequential formation and annihilation of water-filled cavities, thereby enabling transport of the hydrophilic phospholipid head group in a groove outlined by the transmembrane segments M1, M2, M4, and M6, with the hydrocarbon chains following passively, still in the membrane lipid phase.
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Zhou X, Sebastian TT, Graham TR. Auto-inhibition of Drs2p, a yeast phospholipid flippase, by its carboxyl-terminal tail. J Biol Chem 2013; 288:31807-15. [PMID: 24045945 DOI: 10.1074/jbc.m113.481986] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Drs2p, a yeast type IV P-type ATPase (P4-ATPase), or flippase, couples ATP hydrolysis to phosphatidylserine translocation and the establishment of membrane asymmetry. A previous study has shown that affinity-purified Drs2p, possessing an N-terminal tandem affinity purification tag (TAPN-Drs2), retains ATPase and translocase activity, but Drs2p purified using a C-terminal tag (Drs2-TAPC) was inactive. In this study, we show that the ATPase activity of N-terminally purified Drs2p associates primarily with a proteolyzed form of Drs2p lacking the C-terminal cytosolic tail. Truncation of most of the Drs2p C-terminal tail sequence activates its ATPase activity by ∼4-fold. These observations are consistent with the hypothesis that the C-terminal tail of Drs2p is auto-inhibitory to Drs2p activity. Phosphatidylinositol 4-phosphate (PI(4)P) has been shown to positively regulate Drs2p activity in isolated Golgi membranes through interaction with the C-terminal tail. In proteoliposomes reconstituted with purified, N-terminally TAP-tagged Drs2p, both ATPase and flippase activity were significantly higher in the presence of PI(4)P. In contrast, PI(4)P had no significant effect on the activity of a truncated form of Drs2p, which lacked the C-terminal tail. This work provides the first direct evidence, in a purified system, that a phospholipid flippase is subject to auto-inhibition by its C-terminal tail, which can be relieved by a phosphoinositide to stimulate flippase activity.
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Affiliation(s)
- Xiaoming Zhou
- From the Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235
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Xu P, Baldridge RD, Chi RJ, Burd CG, Graham TR. Phosphatidylserine flipping enhances membrane curvature and negative charge required for vesicular transport. ACTA ACUST UNITED AC 2013; 202:875-86. [PMID: 24019533 PMCID: PMC3776346 DOI: 10.1083/jcb.201305094] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The Drs2 flippase increases membrane curvature and anionic phospholipid composition of the membrane by flipping phosphatidylserine, which is critical for vesicular transport between the trans-Golgi network and early endosomes. Vesicle-mediated protein transport between organelles of the secretory and endocytic pathways is strongly influenced by the composition and organization of membrane lipids. In budding yeast, protein transport between the trans-Golgi network (TGN) and early endosome (EE) requires Drs2, a phospholipid translocase in the type IV P-type ATPase family. However, downstream effectors of Drs2 and specific phospholipid substrate requirements for protein transport in this pathway are unknown. Here, we show that the Arf GTPase-activating protein (ArfGAP) Gcs1 is a Drs2 effector that requires a variant of the ArfGAP lipid packing sensor (+ALPS) motif for localization to TGN/EE membranes. Drs2 increases membrane curvature and anionic phospholipid composition of the cytosolic leaflet, both of which are sensed by the +ALPS motif. Using mutant forms of Drs2 and the related protein Dnf1, which alter their ability to recognize phosphatidylserine, we show that translocation of this substrate to the cytosolic leaflet is essential for +ALPS binding and vesicular transport between the EE and the TGN.
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Affiliation(s)
- Peng Xu
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235
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Baldridge RD, Xu P, Graham TR. Type IV P-type ATPases distinguish mono- versus diacyl phosphatidylserine using a cytofacial exit gate in the membrane domain. J Biol Chem 2013; 288:19516-27. [PMID: 23709217 PMCID: PMC3707653 DOI: 10.1074/jbc.m113.476911] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 05/09/2013] [Indexed: 12/22/2022] Open
Abstract
Type IV P-type ATPases (P4-ATPases) use the energy from ATP to "flip" phospholipid across a lipid bilayer, facilitating membrane trafficking events and maintaining the characteristic plasma membrane phospholipid asymmetry. Preferred translocation substrates for the budding yeast P4-ATPases Dnf1 and Dnf2 include lysophosphatidylcholine, lysophosphatidylethanolamine, derivatives of phosphatidylcholine and phosphatidylethanolamine containing a 7-nitro-2-1,3-benzoxadiazol-4-yl (NBD) group on the sn-2 C6 position, and were presumed to include phosphatidylcholine and phosphatidylethanolamine species with two intact acyl chains. We previously identified several mutations in Dnf1 transmembrane (TM) segments 1 through 4 that greatly enhance recognition and transport of NBD phosphatidylserine (NBD-PS). Here we show that most of these Dnf1 mutants cannot flip diacylated PS to the cytosolic leaflet to establish PS asymmetry. However, mutation of a highly conserved asparagine (Asn-550) in TM3 allowed Dnf1 to restore plasma membrane PS asymmetry in a strain deficient for the P4-ATPase Drs2, the primary PS flippase. Moreover, Dnf1 N550 mutants could replace the Drs2 requirement for growth at low temperature. A screen for additional Dnf1 mutants capable of replacing Drs2 function identified substitutions of TM1 and 2 residues, within a region called the exit gate, that permit recognition of dually acylated PS. These TM1, 2, and 3 residues coordinate with the "proline + 4" residue within TM4 to determine substrate preference at the exit gate. Moreover, residues from Atp8a1, a mammalian ortholog of Drs2, in these positions allow PS recognition by Dnf1. These studies indicate that Dnf1 poorly recognizes diacylated phospholipid and define key substitutions enabling recognition of endogenous PS.
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Affiliation(s)
- Ryan D. Baldridge
- From the Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235
| | - Peng Xu
- From the Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235
| | - Todd R. Graham
- From the Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235
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van der Mark VA, Elferink RPJO, Paulusma CC. P4 ATPases: flippases in health and disease. Int J Mol Sci 2013; 14:7897-922. [PMID: 23579954 PMCID: PMC3645723 DOI: 10.3390/ijms14047897] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 03/28/2013] [Accepted: 04/07/2013] [Indexed: 12/26/2022] Open
Abstract
P4 ATPases catalyze the translocation of phospholipids from the exoplasmic to the cytosolic leaflet of biological membranes, a process termed “lipid flipping”. Accumulating evidence obtained in lower eukaryotes points to an important role for P4 ATPases in vesicular protein trafficking. The human genome encodes fourteen P4 ATPases (fifteen in mouse) of which the cellular and physiological functions are slowly emerging. Thus far, deficiencies of at least two P4 ATPases, ATP8B1 and ATP8A2, are the cause of severe human disease. However, various mouse models and in vitro studies are contributing to our understanding of the cellular and physiological functions of P4-ATPases. This review summarizes current knowledge on the basic function of these phospholipid translocating proteins, their proposed action in intracellular vesicle transport and their physiological role.
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Affiliation(s)
- Vincent A van der Mark
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, Meibergdreef 69-71, 1105 BK Amsterdam, The Netherlands.
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