1
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Litschel T, Kelley CF, Cheng X, Babl L, Mizuno N, Case LB, Schwille P. Membrane-induced 2D phase separation of the focal adhesion protein talin. Nat Commun 2024; 15:4986. [PMID: 38862544 PMCID: PMC11166923 DOI: 10.1038/s41467-024-49222-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 05/22/2024] [Indexed: 06/13/2024] Open
Abstract
Focal adhesions form liquid-like assemblies around activated integrin receptors at the plasma membrane. How they achieve their flexible properties is not well understood. Here, we use recombinant focal adhesion proteins to reconstitute the core structural machinery in vitro. We observe liquid-liquid phase separation of the core focal adhesion proteins talin and vinculin for a spectrum of conditions and interaction partners. Intriguingly, we show that binding to PI(4,5)P2-containing membranes triggers phase separation of these proteins on the membrane surface, which in turn induces the enrichment of integrin in the clusters. We suggest a mechanism by which 2-dimensional biomolecular condensates assemble on membranes from soluble proteins in the cytoplasm: lipid-binding triggers protein activation and thus, liquid-liquid phase separation of these membrane-bound proteins. This could explain how early focal adhesions maintain a structured and force-resistant organization into the cytoplasm, while still being highly dynamic and able to quickly assemble and disassemble.
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Affiliation(s)
- Thomas Litschel
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Martinsried, Germany.
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA.
| | - Charlotte F Kelley
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Xiaohang Cheng
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Leon Babl
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Naoko Mizuno
- Department of Structural Cell Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
- Laboratory of Structural Cell Biology, National Institutes of Health, Bethesda, MD, USA
| | - Lindsay B Case
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Petra Schwille
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Martinsried, Germany.
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2
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Picas L, André-Arpin C, Comunale F, Bousquet H, Tsai FC, Rico F, Maiuri P, Pernier J, Bodin S, Nicot AS, Laporte J, Bassereau P, Goud B, Gauthier-Rouvière C, Miserey S. BIN1 regulates actin-membrane interactions during IRSp53-dependent filopodia formation. Commun Biol 2024; 7:549. [PMID: 38724689 PMCID: PMC11082164 DOI: 10.1038/s42003-024-06168-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 04/09/2024] [Indexed: 05/12/2024] Open
Abstract
Amphiphysin 2 (BIN1) is a membrane and actin remodeling protein mutated in congenital and adult centronuclear myopathies. Here, we report an unexpected function of this N-BAR domain protein BIN1 in filopodia formation. We demonstrated that BIN1 expression is necessary and sufficient to induce filopodia formation. BIN1 is present at the base of forming filopodia and all along filopodia, where it colocalizes with F-actin. We identify that BIN1-mediated filopodia formation requires IRSp53, which allows its localization at negatively-curved membrane topologies. Our results show that BIN1 bundles actin in vitro. Finally, we identify that BIN1 regulates the membrane-to-cortex architecture and functions as a molecular platform to recruit actin-binding proteins, dynamin and ezrin, to promote filopodia formation.
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Affiliation(s)
- Laura Picas
- Institut de Recherche en Infectiologie de Montpellier (IRIM), University of Montpellier, CNRS UMR 9004, Montpellier, France.
| | - Charlotte André-Arpin
- Institut de Recherche en Infectiologie de Montpellier (IRIM), University of Montpellier, CNRS UMR 9004, Montpellier, France
| | - Franck Comunale
- CRBM, University of Montpellier, CNRS UMR 5237, Montpellier, France
| | - Hugo Bousquet
- Institut Curie, CNRS UMR 144, PSL Research University, Paris, France
| | - Feng-Ching Tsai
- Institut Curie, CNRS UMR 168, PSL Research University, Paris, France
| | - Félix Rico
- Aix-Marseille Université, U1325 INSERM, DyNaMo, Turing center for living systems, Marseille, France
| | - Paolo Maiuri
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università degli Studi di Napoli Federico II, Naples, Italy
| | - Julien Pernier
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Stéphane Bodin
- CRBM, University of Montpellier, CNRS UMR 5237, Montpellier, France
| | - Anne-Sophie Nicot
- Grenoble Alpes University, INSERM U1216, Grenoble Institut Neurosciences, Grenoble, France
| | - Jocelyn Laporte
- Department of Translational Medicine, IGBMC, U1258, UMR7104 Strasbourg University, Collège de France, Illkirch, France
| | | | - Bruno Goud
- Institut Curie, CNRS UMR 144, PSL Research University, Paris, France
| | | | - Stéphanie Miserey
- Institut Curie, CNRS UMR 144, PSL Research University, Paris, France.
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3
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Narayan KB, Baeyens L, James HP, Swain A, Baumgart T. Fluorescence imaging of lamellipodin-mediated biomolecular condensates on solid supported lipid bilayer membranes. Methods Enzymol 2024; 700:33-48. [PMID: 38971606 DOI: 10.1016/bs.mie.2024.04.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/08/2024]
Abstract
Biomolecular condensates play a major role in numerous cellular processes, including several that occur on the surface of lipid bilayer membranes. There is increasing evidence that cellular membrane trafficking phenomena, including the internalization of the plasma membrane through endocytosis, are mediated by multivalent protein-protein interactions that can lead to phase separation. We have recently found that proteins involved in the clathrin-independent endocytic pathway named Fast Endophilin Mediated Endocytosis can undergo liquid-liquid phase separation (LLPS) in solution and on lipid bilayer membranes. Here, the protein solution concentrations required for phase separation to be observed are significantly smaller compared to those required for phase separation in solution. LLPS is challenging to systematically characterize in cellular systems in general, and on biological membranes in particular. Model membrane approaches are more suitable for this purpose as they allow for precise control over the nature and amount of the components present in a mixture. Here we describe a method that enables the imaging of LLPS domain formation on solid supported lipid bilayers. These allow for facile imaging, provide long-term stability, and avoid clustering of vesicles and vesicle-attached features (such as buds and tethers) in the presence of multi-valent membrane interacting proteins.
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Affiliation(s)
- Karthik B Narayan
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA
| | - Laura Baeyens
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA
| | - Honey Priya James
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA
| | - Aparna Swain
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA
| | - Tobias Baumgart
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA.
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4
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Liebe NL, Mey I, Vuong L, Shikho F, Geil B, Janshoff A, Steinem C. Bioinspired Membrane Interfaces: Controlling Actomyosin Architecture and Contractility. ACS APPLIED MATERIALS & INTERFACES 2023; 15:11586-11598. [PMID: 36848241 PMCID: PMC9999349 DOI: 10.1021/acsami.3c00061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 02/16/2023] [Indexed: 06/18/2023]
Abstract
The creation of biologically inspired artificial lipid bilayers on planar supports provides a unique platform to study membrane-confined processes in a well-controlled setting. At the plasma membrane of mammalian cells, the linkage of the filamentous (F)-actin network is of pivotal importance leading to cell-specific and dynamic F-actin architectures, which are essential for the cell's shape, mechanical resilience, and biological function. These networks are established through the coordinated action of diverse actin-binding proteins and the presence of the plasma membrane. Here, we established phosphatidylinositol-4,5-bisphosphate (PtdIns[4,5]P2)-doped supported planar lipid bilayers to which contractile actomyosin networks were bound via the membrane-actin linker ezrin. This membrane system, amenable to high-resolution fluorescence microscopy, enabled us to analyze the connectivity and contractility of the actomyosin network. We found that the network architecture and dynamics are not only a function of the PtdIns[4,5]P2 concentration but also depend on the presence of negatively charged phosphatidylserine (PS). PS drives the attached network into a regime, where low but physiologically relevant connectivity to the membrane results in strong contractility of the actomyosin network, emphasizing the importance of the lipid composition of the membrane interface.
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Affiliation(s)
- Nils L. Liebe
- Institut
für Organische und Biomolekulare Chemie, Georg-August Universität, Tammannstr. 2, Göttingen 37077, Germany
| | - Ingo Mey
- Institut
für Organische und Biomolekulare Chemie, Georg-August Universität, Tammannstr. 2, Göttingen 37077, Germany
| | - Loan Vuong
- Institut
für Organische und Biomolekulare Chemie, Georg-August Universität, Tammannstr. 2, Göttingen 37077, Germany
| | - Fadi Shikho
- Institut
für Organische und Biomolekulare Chemie, Georg-August Universität, Tammannstr. 2, Göttingen 37077, Germany
| | - Burkhard Geil
- Institut
für Physikalische Chemie, Georg-August
Universität, Tammannstr. 6, Göttingen 37077, Germany
| | - Andreas Janshoff
- Institut
für Physikalische Chemie, Georg-August
Universität, Tammannstr. 6, Göttingen 37077, Germany
| | - Claudia Steinem
- Institut
für Organische und Biomolekulare Chemie, Georg-August Universität, Tammannstr. 2, Göttingen 37077, Germany
- Max-Planck-Institut
für Dynamik und Selbstorganisation, Am Fassberg 17, Göttingen 37077, Germany
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5
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Santamaria A, Carrascosa-Tejedor J, Guzmán E, Zaccai NR, Maestro A. Unravelling the orientation of the inositol-biphosphate ring and its dependence on phosphatidylinositol 4,5-bisphosphate cluster formation in model membranes. J Colloid Interface Sci 2023; 629:785-795. [PMID: 36195018 DOI: 10.1016/j.jcis.2022.09.095] [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: 06/06/2022] [Revised: 09/03/2022] [Accepted: 09/18/2022] [Indexed: 10/14/2022]
Abstract
HYPOTHESIS Inositol phospholipids are well known to form clusters in the cytoplasmic leaflet of the plasma membrane that are responsible for the interaction and recruitment of proteins involved in key biological processes like endocytosis, ion channel activation and secondary messenger production. Although their phosphorylated inositol ring headgroup plays an important role in protein binding, its orientation with respect to the plane of the membrane and its lateral packing density has not been previously described experimentally. EXPERIMENTS Here, we study phosphatidylinositol 4,5-bisphosphate (PIP2) planar model membranes in the form of Langmuir monolayers by surface pressure-area isotherms, Brewster angle microscopy and neutron reflectometry to elucidate the relation between lateral (in-plane) and perpendicular (out-of-plane) molecular organization of PIP2. FINDINGS Different surface areas were explored through monolayer compression, allowing us to correlate the formation of transient PIP2 clusters with the change in orientation of the inositol-biphosphate headgroup, which was experimentally determined by neutron reflectometry.
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Affiliation(s)
- Andreas Santamaria
- Large Scale Structures Group, Institut Laue-Langevin, 71 Avenue des Martyrs, 38042 Grenoble, Cedex 9, France; Departamento de Química-Física, Facultad de Ciencias Químicas, Universidad Complutense, Ciudad Universitaria s/n, 28040 Madrid, Spain
| | - Javier Carrascosa-Tejedor
- Large Scale Structures Group, Institut Laue-Langevin, 71 Avenue des Martyrs, 38042 Grenoble, Cedex 9, France; Division of Pharmacy and Optometry, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Eduardo Guzmán
- Departamento de Química-Física, Facultad de Ciencias Químicas, Universidad Complutense, Ciudad Universitaria s/n, 28040 Madrid, Spain; Instituto Pluridisciplinar, Universidad Complutense de Madrid, Paseo Juan XXIII 1, 28040 Madrid, Spain.
| | - Nathan R Zaccai
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB22 7QQ, United Kingdom.
| | - Armando Maestro
- Centro de Fı́sica de Materiales (CSIC, UPV/EHU) - Materials Physics Center MPC, Paseo Manuel de Lardizabal 5, E-20018 San Sebastián, Spain; IKERBASQUE-Basque Foundation for Science, Plaza Euskadi 5, Bilbao 48009, Spain.
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6
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Kumar M, Singh A, Del Secco B, Baranov MV, van den Bogaart G, Sacanna S, Thutupalli S. Assembling anisotropic colloids using curvature-mediated lipid sorting. SOFT MATTER 2022; 18:1757-1766. [PMID: 35072193 DOI: 10.1039/d1sm01517f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The use of colloid supported lipid bilayers (CSLBs) for assembling colloidal structures has been of recent interest. Here, we use multi-component lipid bilayer membranes formed around anisotropic colloids and show that the curvature anisotropy of the colloids drives a sorting of the lipids in the membrane along the colloids. We then exploit this curvature-sensitive lipid sorting to create "shape-anisotropic patchy colloids" - specifically, we use colloids with six rods sticking out of a central cubic core, "hexapods", for this purpose and demonstrate that membrane patches self-assemble at the tip of each of the six colloidal rods. The membrane patches are rendered sticky using biotinylated lipids in complement with a biotin-binding streptavidin protein. Finally, using these "shape-anisotropic patchy colloids", we demonstrate the directed assembly of colloidal links, paving the way for the creation of heterogeneous and flexible colloidal structures.
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Affiliation(s)
- Manoj Kumar
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India.
| | - Anupam Singh
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India.
| | - Benedetta Del Secco
- Molecular Design Institute, Department of Chemistry, New York University, New York, NY, USA
| | - Maksim V Baranov
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, The Netherlands
| | - Geert van den Bogaart
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, The Netherlands
| | - Stefano Sacanna
- Molecular Design Institute, Department of Chemistry, New York University, New York, NY, USA
| | - Shashi Thutupalli
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India.
- International Centre for Theoretical Sciences, Tata Institute of Fundamental Research, Bangalore, India
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7
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El Alaoui F, Casuso I, Sanchez-Fuentes D, Arpin-Andre C, Rathar R, Baecker V, Castro A, Lorca T, Viaud J, Vassilopoulos S, Carretero-Genevrier A, Picas L. Structural organization and dynamics of FCHo2 docking on membranes. eLife 2022; 11:e73156. [PMID: 35044298 PMCID: PMC8798043 DOI: 10.7554/elife.73156] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 01/18/2022] [Indexed: 11/24/2022] Open
Abstract
Clathrin-mediated endocytosis (CME) is a central trafficking pathway in eukaryotic cells regulated by phosphoinositides. The plasma membrane phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2) plays an instrumental role in driving CME initiation. The F-BAR domain-only protein 1 and 2 complex (FCHo1/2) is among the early proteins that reach the plasma membrane, but the exact mechanisms triggering its recruitment remain elusive. Here, we show the molecular dynamics of FCHo2 self-assembly on membranes by combining minimal reconstituted in vitro and cellular systems. Our results indicate that PI(4,5)P2 domains assist FCHo2 docking at specific membrane regions, where it self-assembles into ring-like-shaped protein patches. We show that the binding of FCHo2 on cellular membranes promotes PI(4,5)P2 clustering at the boundary of cargo receptors and that this accumulation enhances clathrin assembly. Thus, our results provide a mechanistic framework that could explain the recruitment of early PI(4,5)P2-interacting proteins at endocytic sites.
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Affiliation(s)
- Fatima El Alaoui
- Institut de Recherche en Infectiologie de Montpellier (IRIM), CNRS UMR 9004, Université de MontpellierMontpellierFrance
| | | | - David Sanchez-Fuentes
- Institut d'Électronique et des Systèmes (IES), CNRS UMR 5214, Université de MontpellierMontpellierFrance
| | - Charlotte Arpin-Andre
- Institut de Recherche en Infectiologie de Montpellier (IRIM), CNRS UMR 9004, Université de MontpellierMontpellierFrance
| | - Raissa Rathar
- Institut d'Électronique et des Systèmes (IES), CNRS UMR 5214, Université de MontpellierMontpellierFrance
| | - Volker Baecker
- Montpellier Ressources Imagerie, BioCampus Montpellier, CNRS, INSERM, Université de MontpellierMontpellierFrance
| | - Anna Castro
- Centre de Biologie Cellulaire de Montpellier (CRBM), CNRS UMR UMR 5237, Université de MontpellierMontpellierFrance
| | - Thierry Lorca
- Centre de Biologie Cellulaire de Montpellier (CRBM), CNRS UMR UMR 5237, Université de MontpellierMontpellierFrance
| | - Julien Viaud
- INSERM UMR1297, Institute of Metabolic and Cardiovascular Diseases (I2MC), University of Toulouse, Paul Sabatier UniversityToulouseFrance
| | - Stéphane Vassilopoulos
- Sorbonne Université, INSERM, Institute of Myology, Centre of Research in Myology, UMRS 974ParisFrance
| | - Adrian Carretero-Genevrier
- Institut d'Électronique et des Systèmes (IES), CNRS UMR 5214, Université de MontpellierMontpellierFrance
| | - Laura Picas
- Institut de Recherche en Infectiologie de Montpellier (IRIM), CNRS UMR 9004, Université de MontpellierMontpellierFrance
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8
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Azouz M, Feuillie C, Lafleur M, Molinari M, Lecomte S. Interaction of Tau construct K18 with model lipid membranes. NANOSCALE ADVANCES 2021; 3:4244-4253. [PMID: 36132846 PMCID: PMC9417262 DOI: 10.1039/d1na00055a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 06/16/2021] [Indexed: 06/12/2023]
Abstract
One of the hallmarks of Alzheimer's disease (AD) is the formation of neurofibrillary tangles, resulting from the aggregation of the tubulin associated unit protein (Tau), which holds a vital role in maintaining neuron integrity in a healthy brain. The development of such aggregates and their deposition in the brain seem to correlate with the onset of neurodegeneration processes. The misfolding and subsequent aggregation of the protein into paired helical filaments that further form the tangles, lead to dysfunction of the protein with neuronal loss and cognitive decline. The aggregation of the protein then seems to be a causative factor of the neurodegeneration associated with AD. The hypothesis of an involvement of the membrane in modulating the misfolding and assembly of Tau into paired helical filaments attracts increasing interests. To provide more insight about how lipids can modulate the interactions with Tau, we have conducted a comprehensive Atomic Force Microscopy (AFM) study involving supported lipid bilayers of controlled compositions with the Tau microtubule-binding construct K18. Particularly, the effects of zwitterionic and negatively charged phospholipids on the interaction have been investigated. Deleterious solubilization effects have been evidenced on fluid zwitterionic membranes as well as an inability of K18 to fragment gel phases. The role of negative lipids in the aggregation of the peptide and the particular ability of phosphatidylinositol-4,5-bisphosphate (PIP2) in inducing K18 fibrillization on membranes are also reported.
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Affiliation(s)
- Mehdi Azouz
- Institute of Chemistry and Biology of Membranes and Nano-Objects, CNRS, Université de Bordeaux, INP Bordeaux, UMR5248 allée Geoffroy Saint Hilaire 33600 Pessac France
- Department of Chemistry, Université de Montréal Succursale Centre-Ville Montréal C.P. 6128 Québec Canada H3C 3J7
| | - Cécile Feuillie
- Institute of Chemistry and Biology of Membranes and Nano-Objects, CNRS, Université de Bordeaux, INP Bordeaux, UMR5248 allée Geoffroy Saint Hilaire 33600 Pessac France
| | - Michel Lafleur
- Department of Chemistry, Université de Montréal Succursale Centre-Ville Montréal C.P. 6128 Québec Canada H3C 3J7
| | - Michaël Molinari
- Institute of Chemistry and Biology of Membranes and Nano-Objects, CNRS, Université de Bordeaux, INP Bordeaux, UMR5248 allée Geoffroy Saint Hilaire 33600 Pessac France
| | - Sophie Lecomte
- Institute of Chemistry and Biology of Membranes and Nano-Objects, CNRS, Université de Bordeaux, INP Bordeaux, UMR5248 allée Geoffroy Saint Hilaire 33600 Pessac France
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9
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Szuba A, Bano F, Castro-Linares G, Iv F, Mavrakis M, Richter RP, Bertin A, Koenderink GH. Membrane binding controls ordered self-assembly of animal septins. eLife 2021; 10:63349. [PMID: 33847563 PMCID: PMC8099429 DOI: 10.7554/elife.63349] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 04/12/2021] [Indexed: 12/23/2022] Open
Abstract
Septins are conserved cytoskeletal proteins that regulate cell cortex mechanics. The mechanisms of their interactions with the plasma membrane remain poorly understood. Here, we show by cell-free reconstitution that binding to flat lipid membranes requires electrostatic interactions of septins with anionic lipids and promotes the ordered self-assembly of fly septins into filamentous meshworks. Transmission electron microscopy reveals that both fly and mammalian septin hexamers form arrays of single and paired filaments. Atomic force microscopy and quartz crystal microbalance demonstrate that the fly filaments form mechanically rigid, 12- to 18-nm thick, double layers of septins. By contrast, C-terminally truncated septin mutants form 4-nm thin monolayers, indicating that stacking requires the C-terminal coiled coils on DSep2 and Pnut subunits. Our work shows that membrane binding is required for fly septins to form ordered arrays of single and paired filaments and provides new insights into the mechanisms by which septins may regulate cell surface mechanics.
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Affiliation(s)
- Agata Szuba
- AMOLF, Department of Living Matter, Biological Soft Matter group, Amsterdam, Netherlands
| | - Fouzia Bano
- School of Biomedical Sciences, Faculty of Biological Sciences, Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom.,School of Physics and Astronomy, Faculty of Engineering and Physical Sciences, University of Leeds, Leeds, United Kingdom.,Bragg Centre for Materials Research, University of Leeds, Leeds, United Kingdom
| | - Gerard Castro-Linares
- AMOLF, Department of Living Matter, Biological Soft Matter group, Amsterdam, Netherlands.,Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, Netherlands
| | - Francois Iv
- Institut Fresnel, CNRS, Aix-Marseille Univ, Centrale Marseille, Marseille, France
| | - Manos Mavrakis
- Institut Fresnel, CNRS, Aix-Marseille Univ, Centrale Marseille, Marseille, France
| | - Ralf P Richter
- School of Biomedical Sciences, Faculty of Biological Sciences, Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom.,School of Physics and Astronomy, Faculty of Engineering and Physical Sciences, University of Leeds, Leeds, United Kingdom.,Bragg Centre for Materials Research, University of Leeds, Leeds, United Kingdom
| | - Aurélie Bertin
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, Paris, France.,Sorbonne Université, Paris, France
| | - Gijsje H Koenderink
- AMOLF, Department of Living Matter, Biological Soft Matter group, Amsterdam, Netherlands.,Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, Netherlands
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10
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Characterization of Protein-Phospholipid/Membrane Interactions Using a "Membrane-on-a-Chip" Microfluidic System. Methods Mol Biol 2021. [PMID: 33481237 DOI: 10.1007/978-1-0716-1142-5_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
It is now clear that organelles of a mammalian cell can be distinguished by phospholipid profiles, both as ratios of common phospholipids and by the absence or presence of certain phospholipids. Organelle-specific phospholipids can be used to provide a specific shape and fluidity to the membrane and/or used to recruit and/or traffic proteins to the appropriate subcellular location and to restrict protein function to this location. Studying the interactions of proteins with specific phospholipids using soluble derivatives in isolation does not always provide useful information because the context in which the headgroups are presented almost always matters. Our laboratory has shown this circumstance to be the case for a viral protein binding to phosphoinositides in solution and in membranes. The system we have developed to study protein-phospholipid interactions in the context of a membrane benefits from the creation of tailored membranes in a channel of a microfluidic device, with a fluorescent lipid in the membrane serving as an indirect reporter of protein binding. This system is amenable to the study of myriad interactions occurring at a membrane surface as long as a net change in surface charge occurs in response to the binding event of interest.
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11
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Sun S, Liu C, Rodriguez Melendez D, Yang T, Cremer PS. Immobilization of Phosphatidylinositides Revealed by Bilayer Leaflet Decoupling. J Am Chem Soc 2020; 142:13003-13010. [DOI: 10.1021/jacs.0c03800] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Simou Sun
- Department of Chemistry, Penn State University, University Park, Pennsylvania 16802, United States
| | - Chang Liu
- Department of Chemistry, Penn State University, University Park, Pennsylvania 16802, United States
| | - Danixa Rodriguez Melendez
- Department of Chemistry, University of Puerto Rico at Cayey, Cayey, Puerto Rico 00737, United States
| | - Tinglu Yang
- Department of Chemistry, Penn State University, University Park, Pennsylvania 16802, United States
| | - Paul S. Cremer
- Department of Chemistry, Penn State University, University Park, Pennsylvania 16802, United States
- Department of Biochemistry and Molecular Biology, Penn State University, University Park, Pennsylvania 16802, United States
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12
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Kelley CF, Litschel T, Schumacher S, Dedden D, Schwille P, Mizuno N. Phosphoinositides regulate force-independent interactions between talin, vinculin, and actin. eLife 2020; 9:e56110. [PMID: 32657269 PMCID: PMC7384861 DOI: 10.7554/elife.56110] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 07/10/2020] [Indexed: 12/25/2022] Open
Abstract
Focal adhesions (FA) are large macromolecular assemblies which help transmit mechanical forces and regulatory signals between the extracellular matrix and an interacting cell. Two key proteins talin and vinculin connecting integrin to actomyosin networks in the cell. Both proteins bind to F-actin and each other, providing a foundation for network formation within FAs. However, the underlying mechanisms regulating their engagement remain unclear. Here, we report on the results of in vitro reconstitution of talin-vinculin-actin assemblies using synthetic membrane systems. We find that neither talin nor vinculin alone recruit actin filaments to the membrane. In contrast, phosphoinositide-rich membranes recruit and activate talin, and the membrane-bound talin then activates vinculin. Together, the two proteins then link actin to the membrane. Encapsulation of these components within vesicles reorganized actin into higher-order networks. Notably, these observations were made in the absence of applied force, whereby we infer that the initial assembly stage of FAs is force independent. Our findings demonstrate that the local membrane composition plays a key role in controlling the stepwise recruitment, activation, and engagement of proteins within FAs.
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Affiliation(s)
- Charlotte F Kelley
- Max Planck Institute of Biochemistry, Department of Structural Cell BiologyMartinsriedGermany
| | - Thomas Litschel
- Max Planck Institute of Biochemistry, Department of Cellular and Molecular BiophysicsMartinsriedGermany
| | - Stephanie Schumacher
- Max Planck Institute of Biochemistry, Department of Structural Cell BiologyMartinsriedGermany
| | - Dirk Dedden
- Max Planck Institute of Biochemistry, Department of Structural Cell BiologyMartinsriedGermany
| | - Petra Schwille
- Max Planck Institute of Biochemistry, Department of Cellular and Molecular BiophysicsMartinsriedGermany
| | - Naoko Mizuno
- Max Planck Institute of Biochemistry, Department of Structural Cell BiologyMartinsriedGermany
- Laboratory of Structural Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of HealthBethesdaUnited States
- National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of HealthBethesdaUnited States
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13
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Schäfer J, Nehls J, Schön M, Mey I, Steinem C. Leaflet-Dependent Distribution of PtdIns[4,5]P 2 in Supported Model Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:1320-1328. [PMID: 31951413 DOI: 10.1021/acs.langmuir.9b03793] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Supported planar lipid bilayers (SLBs) prepared by spreading of unilamellar vesicles on hydrophilic substrates such as silicon dioxide are frequently used to investigate lipid-protein interactions by means of surface-sensitive methods. In recent years, the receptor lipid phosphatidylinositol-4,5-bisphosphate (PtdIns[4,5]P2) became particularly important as a significant number of proteins bind to this lipid at the inner leaflet of the plasma membrane. Here, we investigated how the lipid PtdIns[4,5]P2 distributes between the two leaflets of an SLB on SiO2 surfaces. We prepared SLBs on SiO2 by spreading small unilamellar vesicles and quantified the adsorption of PtdIns[4,5]P2 binding proteins providing information about the accessibility of PtdIns[4,5]P2. We compared protein binding to PtdIns[4,5]P2 in SLBs with that in lipid monolayers on a 1,1,1-trimethyl-N-(trimethylsilyl)silanamine-functionalized SiO2 surface using reflectometric interference spectroscopy and atomic force microscopy. Our results clearly demonstrate that the accessibility of PtdIns[4,5]P2 for protein binding is reduced in SLBs compared to that in supported hybrid membranes, which is discussed in terms of PtdIns[4,5]P2 distribution in the two leaflets of SLBs.
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Affiliation(s)
- Jonas Schäfer
- Institute of Organic and Biomolecular Chemistry , University of Göttingen , Tammannstrasse 2 , 37077 Göttingen , Germany
| | - Jessica Nehls
- Institute of Organic and Biomolecular Chemistry , University of Göttingen , Tammannstrasse 2 , 37077 Göttingen , Germany
| | - Markus Schön
- Institute of Organic and Biomolecular Chemistry , University of Göttingen , Tammannstrasse 2 , 37077 Göttingen , Germany
| | - Ingo Mey
- Institute of Organic and Biomolecular Chemistry , University of Göttingen , Tammannstrasse 2 , 37077 Göttingen , Germany
| | - Claudia Steinem
- Institute of Organic and Biomolecular Chemistry , University of Göttingen , Tammannstrasse 2 , 37077 Göttingen , Germany
- Max Planck Institute for Dynamics and Self-Organization , Am Fassberg 17 , 37077 Göttingen , Germany
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14
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Abstract
The protein-mediated formation of membrane contacts is a crucial event in many cellular processes ranging from the establishment of organelle contacts to the docking of vesicles to a target membrane. Annexins are Ca2+ regulated membrane-binding proteins implicated in providing such membrane contacts; however, the molecular basis of membrane bridging by annexins is not fully understood. We addressed this central question using annexin A2 (AnxA2) that functions in secretory vesicle exocytosis possibly by providing membrane bridges. By quantitatively analyzing membrane contact formation using a novel assay based on quartz crystal microbalance recordings, we show that monomeric AnxA2 can bridge membrane surfaces Ca2+ dependently. However, this activity depends on an oxidative crosslink involving a cysteine residue in the N-terminal domain and thus formation of disulfide-linked dimers. Alkylated AnxA2 in which this cysteine residue has been modified and AnxA2 mutants lacking the N-terminal domain are not capable of bridging membrane surfaces. In contrast, a heterotetrameric complex comprising two membrane binding AnxA2 subunits linked by a S100A10 dimer can provide membrane contacts irrespective of oxidation status. Thus, monomeric AnxA2 only contains one lipid binding site and AnxA2-mediated linking of membrane surfaces under non-oxidative intracellular conditions most likely requires AnxA2-S100 complex formation.
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15
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Tsai FC, Bertin A, Bousquet H, Manzi J, Senju Y, Tsai MC, Picas L, Miserey-Lenkei S, Lappalainen P, Lemichez E, Coudrier E, Bassereau P. Ezrin enrichment on curved membranes requires a specific conformation or interaction with a curvature-sensitive partner. eLife 2018; 7:37262. [PMID: 30234483 PMCID: PMC6167055 DOI: 10.7554/elife.37262] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 09/14/2018] [Indexed: 01/12/2023] Open
Abstract
One challenge in cell biology is to decipher the biophysical mechanisms governing protein enrichment on curved membranes and the resulting membrane deformation. The ERM protein ezrin is abundant and associated with cellular membranes that are flat, positively or negatively curved. Using in vitro and cell biology approaches, we assess mechanisms of ezrin’s enrichment on curved membranes. We evidence that wild-type ezrin (ezrinWT) and its phosphomimetic mutant T567D (ezrinTD) do not deform membranes but self-assemble anti-parallelly, zipping adjacent membranes. EzrinTD’s specific conformation reduces intermolecular interactions, allows binding to actin filaments, which reduces membrane tethering, and promotes ezrin binding to positively-curved membranes. While neither ezrinTD nor ezrinWT senses negative curvature alone, we demonstrate that interacting with curvature-sensing I-BAR-domain proteins facilitates ezrin enrichment in negatively-curved membrane protrusions. Overall, our work demonstrates that ezrin can tether membranes, or be targeted to curved membranes, depending on conformations and interactions with actin and curvature-sensing binding partners.
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Affiliation(s)
- Feng-Ching Tsai
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France.,Sorbonne Université, Paris, France
| | - Aurelie Bertin
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France.,Sorbonne Université, Paris, France
| | - Hugo Bousquet
- Sorbonne Université, Paris, France.,Compartimentation et dynamique cellulaire, Institut Curie, PSL Research University, CNRS UMR144, Paris, France
| | - John Manzi
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France.,Sorbonne Université, Paris, France
| | - Yosuke Senju
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Meng-Chen Tsai
- Université Côte d'Azur, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne, France.,Département de Microbiologie, Unité des Toxines Bactériennes, Université Paris Descartes, Institut Pasteur, Paris, France
| | - Laura Picas
- Institut de Recherche en Infectiologie de Montpellier (IRIM), CNRS UMR 9004, Montpellier, France
| | - Stephanie Miserey-Lenkei
- Sorbonne Université, Paris, France.,Compartimentation et dynamique cellulaire, Institut Curie, PSL Research University, CNRS UMR144, Paris, France
| | - Pekka Lappalainen
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Emmanuel Lemichez
- Département de Microbiologie, Unité des Toxines Bactériennes, Université Paris Descartes, Institut Pasteur, Paris, France
| | - Evelyne Coudrier
- Sorbonne Université, Paris, France.,Compartimentation et dynamique cellulaire, Institut Curie, PSL Research University, CNRS UMR144, Paris, France
| | - Patricia Bassereau
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France.,Sorbonne Université, Paris, France
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16
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Beber A, Alqabandi M, Prévost C, Viars F, Lévy D, Bassereau P, Bertin A, Mangenot S. Septin‐based readout of PI(4,5)P2 incorporation into membranes of giant unilamellar vesicles. Cytoskeleton (Hoboken) 2018; 76:92-103. [DOI: 10.1002/cm.21480] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 07/05/2018] [Accepted: 07/10/2018] [Indexed: 01/27/2023]
Affiliation(s)
- Alexandre Beber
- Laboratoire Physico Chimie CurieInstitut Curie, PSL Research University Paris France
- Sorbonne Université Paris France
| | - Maryam Alqabandi
- Laboratoire Physico Chimie CurieInstitut Curie, PSL Research University Paris France
- Sorbonne Université Paris France
| | - Coline Prévost
- Laboratoire Physico Chimie CurieInstitut Curie, PSL Research University Paris France
- Sorbonne Université Paris France
| | - Fanny Viars
- Institut des maladies métaboliques et cardiovasculairesUMR1048, Inserm/Université Paul Sabatier Toulouse France
| | - Daniel Lévy
- Laboratoire Physico Chimie CurieInstitut Curie, PSL Research University Paris France
- Sorbonne Université Paris France
| | - Patricia Bassereau
- Laboratoire Physico Chimie CurieInstitut Curie, PSL Research University Paris France
- Sorbonne Université Paris France
| | - Aurélie Bertin
- Laboratoire Physico Chimie CurieInstitut Curie, PSL Research University Paris France
- Sorbonne Université Paris France
| | - Stéphanie Mangenot
- Laboratoire Physico Chimie CurieInstitut Curie, PSL Research University Paris France
- Sorbonne Université Paris France
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17
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Schön M, Mey I, Steinem C. Influence of cross-linkers on ezrin-bound minimal actin cortices. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2018; 144:91-101. [PMID: 30093083 DOI: 10.1016/j.pbiomolbio.2018.07.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 07/13/2018] [Accepted: 07/31/2018] [Indexed: 12/21/2022]
Abstract
The actin cortex is a thin network coupled to the plasma membrane of cells, responsible for e.g., cell shape, motility, growth and division. Several model systems for minimal actin cortices (MACs) have been discussed in literature trying to mimic the complex interplay of membrane and actin. We recapitulate on different types of MACs using either three dimensional droplet interfaces or lipid bilayers to which F-actin networks are attached to or planar lipid bilayers with bound actin networks. Binding of the network to the membrane interface significantly influences its properties as well as its dynamics. This in turn also influences, how cross-linkers as well as myosin motors act on the network. Here, we describe the coupling of a filamentous actin network to a model membrane via the protein ezrin, a member of the ezrin-radixin-moesin family, which forms a direct linkage between the plasma membrane and the cortical web. Ezrin binding to the membrane is achieved by the lipid PtdIns(4,5)P2, while attachment to F-actin is mediated via the C-terminal domain of the protein leading to a two dimensional arrangement of actin filaments on the membrane. Addition of cross-linkers such as fascin and α-actinin influences the architecture of the actin network, which we have investigated by means of fluorescence microscopy. The results are discussed in terms of the dynamics of the filaments on the membrane surface.
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Affiliation(s)
- Markus Schön
- Georg-August Universität Göttingen, Institut für Organische und Biomolekulare Chemie, Tammannstr. 2, 37077, Göttingen, Germany
| | - Ingo Mey
- Georg-August Universität Göttingen, Institut für Organische und Biomolekulare Chemie, Tammannstr. 2, 37077, Göttingen, Germany.
| | - Claudia Steinem
- Georg-August Universität Göttingen, Institut für Organische und Biomolekulare Chemie, Tammannstr. 2, 37077, Göttingen, Germany.
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18
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Nöding H, Schön M, Reinermann C, Dörrer N, Kürschner A, Geil B, Mey I, Heussinger C, Janshoff A, Steinem C. Rheology of Membrane-Attached Minimal Actin Cortices. J Phys Chem B 2018; 122:4537-4545. [DOI: 10.1021/acs.jpcb.7b11491] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Helen Nöding
- Institut für Physikalische Chemie, Georg August Universität Göttingen, Tammannstr. 6, 37077 Göttingen, Germany
| | - Markus Schön
- Institut für Organische und Biomolekulare Chemie, Georg August Universität Göttingen, Tammannstr. 2, 37077 Göttingen, Germany
| | - Corinna Reinermann
- Institut für Organische und Biomolekulare Chemie, Georg August Universität Göttingen, Tammannstr. 2, 37077 Göttingen, Germany
| | - Nils Dörrer
- Institut für Physikalische Chemie, Georg August Universität Göttingen, Tammannstr. 6, 37077 Göttingen, Germany
| | - Aileen Kürschner
- Institut für Organische und Biomolekulare Chemie, Georg August Universität Göttingen, Tammannstr. 2, 37077 Göttingen, Germany
| | - Burkhard Geil
- Institut für Physikalische Chemie, Georg August Universität Göttingen, Tammannstr. 6, 37077 Göttingen, Germany
| | - Ingo Mey
- Institut für Organische und Biomolekulare Chemie, Georg August Universität Göttingen, Tammannstr. 2, 37077 Göttingen, Germany
| | - Claus Heussinger
- Institut für Theoretische Physik, Georg August Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Andreas Janshoff
- Institut für Physikalische Chemie, Georg August Universität Göttingen, Tammannstr. 6, 37077 Göttingen, Germany
| | - Claudia Steinem
- Institut für Organische und Biomolekulare Chemie, Georg August Universität Göttingen, Tammannstr. 2, 37077 Göttingen, Germany
- Max-Planck Institute for Dynamics and Self-Organization, Am Faßberg 17, 37077 Göttingen, Germany
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19
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Lubart Q, Vitet H, Dalonneau F, Le Roy A, Kowalski M, Lourdin M, Ebel C, Weidenhaupt M, Picart C. Role of Phosphorylation in Moesin Interactions with PIP 2-Containing Biomimetic Membranes. Biophys J 2018; 114:98-112. [PMID: 29320700 PMCID: PMC5912500 DOI: 10.1016/j.bpj.2017.10.041] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 10/08/2017] [Accepted: 10/17/2017] [Indexed: 12/26/2022] Open
Abstract
Moesin, a protein of the ezrin, radixin, and moesin family, which links the plasma membrane to the cytoskeleton, is involved in multiple physiological and pathological processes, including viral budding and infection. Its interaction with the plasma membrane occurs via a key phosphoinositide, the phosphatidyl(4,5)inositol-bisphosphate (PIP2), and phosphorylation of residue T558, which has been shown to contribute, in cellulo, to a conformationally open protein. We study the impact of a double phosphomimetic mutation of moesin (T235D, T558D), which mimics the phosphorylation state of the protein, on protein/PIP2/microtubule interactions. Analytical ultracentrifugation in the micromolar range showed moesin in the monomer and dimer forms, with wild-type (WT) moesin containing a slightly larger fraction (∼30%) of dimers than DD moesin (10-20%). Only DD moesin was responsive to PIP2 in its micellar form. Quantitative cosedimentation assays using large unilamellar vesicles and quartz crystal microbalance on supported lipid bilayers containing PIP2 reveal a specific cooperative interaction for DD moesin with an ability to bind two PIP2 molecules simultaneously, whereas WT moesin was able to bind only one. In addition, DD moesin could subsequently interact with microtubules, whereas WT moesin was unable to do so. Altogether, our results point to an important role of these two phosphorylation sites in the opening of moesin: since DD moesin is intrinsically in a more open conformation than WT moesin, this intermolecular interaction is reinforced by its binding to PIP2. We also highlight important differences between moesin and ezrin, which appear to be finely regulated and to exhibit distinct molecular behaviors.
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Affiliation(s)
- Quentin Lubart
- CNRS UMR 5628 (LMGP), University Grenoble Alpes, CEA, CNRS, Grenoble, France; Institut National Polytechnique de Grenoble, University Grenoble Alpes, CEA, CNRS, Grenoble, France
| | - Helene Vitet
- CNRS UMR 5628 (LMGP), University Grenoble Alpes, CEA, CNRS, Grenoble, France; Institut National Polytechnique de Grenoble, University Grenoble Alpes, CEA, CNRS, Grenoble, France
| | - Fabien Dalonneau
- CNRS UMR 5628 (LMGP), University Grenoble Alpes, CEA, CNRS, Grenoble, France; Institut National Polytechnique de Grenoble, University Grenoble Alpes, CEA, CNRS, Grenoble, France
| | - Aline Le Roy
- Institut de Biologie Structurale (IBS), University Grenoble Alpes, CEA, CNRS, Grenoble, France
| | - Mathieu Kowalski
- CNRS UMR 5628 (LMGP), University Grenoble Alpes, CEA, CNRS, Grenoble, France; Institut National Polytechnique de Grenoble, University Grenoble Alpes, CEA, CNRS, Grenoble, France
| | - Morgane Lourdin
- CNRS UMR 5628 (LMGP), University Grenoble Alpes, CEA, CNRS, Grenoble, France; Institut National Polytechnique de Grenoble, University Grenoble Alpes, CEA, CNRS, Grenoble, France
| | - Christine Ebel
- Institut de Biologie Structurale (IBS), University Grenoble Alpes, CEA, CNRS, Grenoble, France
| | - Marianne Weidenhaupt
- CNRS UMR 5628 (LMGP), University Grenoble Alpes, CEA, CNRS, Grenoble, France; Institut National Polytechnique de Grenoble, University Grenoble Alpes, CEA, CNRS, Grenoble, France
| | - Catherine Picart
- CNRS UMR 5628 (LMGP), University Grenoble Alpes, CEA, CNRS, Grenoble, France; Institut National Polytechnique de Grenoble, University Grenoble Alpes, CEA, CNRS, Grenoble, France.
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20
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Neumann BM, Kenney D, Wen Q, Gericke A. Microfluidic device as a facile in vitro tool to generate and investigate lipid gradients. Chem Phys Lipids 2017; 210:109-121. [PMID: 29102758 DOI: 10.1016/j.chemphyslip.2017.10.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 10/05/2017] [Accepted: 10/23/2017] [Indexed: 01/13/2023]
Abstract
This work describes a method that utilizes a microfluidic gradient generator to develop lateral lipid gradients in supported lipid bilayers (SLB). The new methodology provides freedom of choice with respect to the lipid composition of the SLB. In addition, the device has the ability to create a protein or bivalent cation gradient in the aqueous phase above the lipid bilayer which can elicit a gradient specific response in the SLB. To highlight these features we demonstrate that we can create a phosphoinositide gradient on various length scales, ranging from 2mm to 50μm. We further show that a Ca2+ gradient in the aqueous phase above the SLB causes anionic lipid clustering mirroring the cation gradient. We demonstrate this effect for mixed phosphatidylcholine/phosphatidylinositol-4,5-bisphosphate bilayers and fora mixed phosphatidylcholine/phosphatidylserine bilayers. The biomimetic platform can be combined with a Total Internal Reflection Fluorescence (TIRF) microscopy setup, which allows for the convenient observation of the time evolution of the gradient and the interaction of ligands with the lipid bilayer. The method provides unprecedented access to study the dynamics and mechanics of protein-lipid interactions on membranes with micron level gradients, mimicking plasma membrane gradients observed in organisms such as Dictyostelium discodeum and neutrophils.
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Affiliation(s)
- Brittany M Neumann
- Worcester Polytechnic Institute, Department of Chemistry and Biochemistry, USA
| | - Devin Kenney
- Bridgewater State University, Department of Chemical Sciences, USA
| | - Qi Wen
- Worcester Polytechnic Institute, Department of Physics, USA
| | - Arne Gericke
- Worcester Polytechnic Institute, Department of Chemistry and Biochemistry, USA.
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21
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Shengjuler D, Sun S, Cremer PS, Cameron CE. PIP-on-a-chip: A Label-free Study of Protein-phosphoinositide Interactions. J Vis Exp 2017:55869. [PMID: 28784961 PMCID: PMC5613778 DOI: 10.3791/55869] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Numerous cellular proteins interact with membrane surfaces to affect essential cellular processes. These interactions can be directed towards a specific lipid component within a membrane, as in the case of phosphoinositides (PIPs), to ensure specific subcellular localization and/or activation. PIPs and cellular PIP-binding domains have been studied extensively to better understand their role in cellular physiology. We applied a pH modulation assay on supported lipid bilayers (SLBs) as a tool to study protein-PIP interactions. In these studies, pH sensitive ortho-Sulforhodamine B conjugated phosphatidylethanolamine is used to detect protein-PIP interactions. Upon binding of a protein to a PIP-containing membrane surface, the interfacial potential is modulated (i.e. change in local pH), shifting the protonation state of the probe. A case study of the successful usage of the pH modulation assay is presented by using phospholipase C delta1 Pleckstrin Homology (PLC-δ1 PH) domain and phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) interaction as an example. The apparent dissociation constant (Kd,app) for this interaction was 0.39 ± 0.05 µM, similar to Kd,app values obtained by others. As previously observed, the PLC-δ1 PH domain is PI(4,5)P2 specific, shows weaker binding towards phosphatidylinositol 4-phosphate, and no binding to pure phosphatidylcholine SLBs. The PIP-on-a-chip assay is advantageous over traditional PIP-binding assays, including but not limited to low sample volume and no ligand/receptor labeling requirements, the ability to test high- and low-affinity membrane interactions with both small and large molecules, and improved signal to noise ratio. Accordingly, the usage of the PIP-on-a-chip approach will facilitate the elucidation of mechanisms of a wide range of membrane interactions. Furthermore, this method could potentially be used in identifying therapeutics that modulate protein's capacity to interact with membranes.
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Affiliation(s)
- Djoshkun Shengjuler
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University;
| | - Simou Sun
- Department of Chemistry, The Pennsylvania State University
| | - Paul S Cremer
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University; Department of Chemistry, The Pennsylvania State University;
| | - Craig E Cameron
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University;
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22
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Shabardina V, Kramer C, Gerdes B, Braunger J, Cordes A, Schäfer J, Mey I, Grill D, Gerke V, Steinem C. Mode of Ezrin-Membrane Interaction as a Function of PIP2 Binding and Pseudophosphorylation. Biophys J 2017; 110:2710-2719. [PMID: 27332129 DOI: 10.1016/j.bpj.2016.05.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 04/14/2016] [Accepted: 05/05/2016] [Indexed: 12/28/2022] Open
Abstract
Ezrin, a protein of the ezrin, radixin, moesin (ERM) family, provides a regulated linkage between the plasma membrane and the cytoskeleton. The hallmark of this linkage is the activation of ezrin by phosphatidylinositol-4,5-bisphosphate (PIP2) binding and a threonine phosphorylation at position 567. To analyze the influence of these activating factors on the organization of ezrin on lipid membranes and the proposed concomitant oligomer-monomer transition, we made use of supported lipid bilayers in conjunction with atomic force microscopy and fluorescence microscopy. Bilayers doped with either PIP2 as the natural receptor lipid of ezrin or a Ni-nitrilotriacetic acid-equipped lipid to bind the proteins via their His6-tags to the lipid membrane were used to bind two different ezrin variants: ezrin wild-type and ezrin T567D mimicking the phosphorylated state. Using a combination of reflectometric interference spectroscopy, atomic force microscopy, and Förster resonance energy transfer experiments, we show that only the ezrin T567D mutant, upon binding to PIP2-containing bilayers, undergoes a remarkable conformational change, which we attribute to an opening of the conformation resulting in monomeric protein on the lipid bilayer.
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Affiliation(s)
- Victoria Shabardina
- Institute of Medical Biochemistry and Center for Molecular Biology of Inflammation, University of Münster, Münster, Germany
| | - Corinna Kramer
- Institute of Organic and Biomolecular Chemistry, University of Göttingen, Göttingen, Germany
| | - Benjamin Gerdes
- Institute of Organic and Biomolecular Chemistry, University of Göttingen, Göttingen, Germany
| | - Julia Braunger
- Institute of Organic and Biomolecular Chemistry, University of Göttingen, Göttingen, Germany
| | - Andrea Cordes
- Institute of Organic and Biomolecular Chemistry, University of Göttingen, Göttingen, Germany
| | - Jonas Schäfer
- Institute of Organic and Biomolecular Chemistry, University of Göttingen, Göttingen, Germany
| | - Ingo Mey
- Institute of Organic and Biomolecular Chemistry, University of Göttingen, Göttingen, Germany
| | - David Grill
- Institute of Medical Biochemistry and Center for Molecular Biology of Inflammation, University of Münster, Münster, Germany
| | - Volker Gerke
- Institute of Medical Biochemistry and Center for Molecular Biology of Inflammation, University of Münster, Münster, Germany.
| | - Claudia Steinem
- Institute of Organic and Biomolecular Chemistry, University of Göttingen, Göttingen, Germany; Göttingen Center for Molecular Biosciences, Göttingen, Germany.
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23
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Tabaei SR, Guo F, Rutaganira FU, Vafaei S, Choong I, Shokat KM, Glenn JS, Cho NJ. Multistep Compositional Remodeling of Supported Lipid Membranes by Interfacially Active Phosphatidylinositol Kinases. Anal Chem 2016; 88:5042-5. [PMID: 27118725 PMCID: PMC5291064 DOI: 10.1021/acs.analchem.6b01293] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The multienzyme catalytic phosphorylation of phosphatidylinositol (PI) in a supported lipid membrane platform is demonstrated for the first time. One-step treatment with PI 4-kinase IIIβ (PI4Kβ) yielded PI 4-phosphate (PI4P), while a multistep enzymatic cascade of PI4Kβ followed by PIP 5-kinase produced PI-4,5-bisphosphate (PI(4,5)P2 or PIP2). By employing quartz crystal microbalance with dissipation monitoring, we were able to track membrane association of kinase enzymes for the first time as well as detect PI4P and PI(4,5)P2 generation based on subsequent antibody binding to the supported lipid bilayers. Pharmacologic inhibition of PI4Kβ by a small molecule inhibitor was also quantitatively assessed, yielding an EC50 value that agrees well with conventional biochemical readout. Taken together, the development of a PI-containing supported membrane platform coupled with surface-sensitive measurement techniques for kinase studies opens the door to exploring the rich biochemistry and pharmacological targeting of membrane-associated phosphoinositides.
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Affiliation(s)
- Seyed R. Tabaei
- School of Materials Science and Engineering and Centre for Biomimetic Sensor Science, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore
| | - Feng Guo
- Departments of Medicine, Division of Gastroenterology and Hepatology, and Microbiology & Immunology, Stanford University School of Medicine, Stanford, California 94305, United States
| | - Florentine U. Rutaganira
- Howard Hughes Medical Institute, Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, California 94158-2280, United States
| | - Setareh Vafaei
- School of Materials Science and Engineering and Centre for Biomimetic Sensor Science, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore
| | - Ingrid Choong
- Departments of Medicine, Division of Gastroenterology and Hepatology, and Microbiology & Immunology, Stanford University School of Medicine, Stanford, California 94305, United States
| | - Kevan M. Shokat
- Howard Hughes Medical Institute, Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, California 94158-2280, United States
| | - Jeffrey S. Glenn
- Departments of Medicine, Division of Gastroenterology and Hepatology, and Microbiology & Immunology, Stanford University School of Medicine, Stanford, California 94305, United States
- Palo Alto Veterans Administration Medical Center, Palo Alto, California 94304, United States
| | - Nam-Joon Cho
- School of Materials Science and Engineering and Centre for Biomimetic Sensor Science, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore
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24
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Abstract
Vertebrate myosin-IC (Myo1c) is a type-1 myosin that links cell membranes to the cytoskeleton via its actin-binding motor domain and its phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2)-binding tail domain. While it is known that Myo1c bound to PtdIns(4,5)P2 in fluid-lipid bilayers can propel actin filaments in an unloaded motility assay, its ability to develop forces against external load on actin while bound to fluid bilayers has not been explored. Using optical tweezers, we measured the diffusion coefficient of single membrane-bound Myo1c molecules by force-relaxation experiments, and the ability of ensembles of membrane-bound Myo1c molecules to develop and sustain forces. To interpret our results, we developed a computational model that recapitulates the basic features of our experimental ensemble data and suggests that Myo1c ensembles can generate forces parallel to lipid bilayers, with larger forces achieved when the myosin works away from the plane of the membrane or when anchored to slowly diffusing regions.
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25
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Shi X, Kohram M, Zhuang X, Smith AW. Interactions and Translational Dynamics of Phosphatidylinositol Bisphosphate (PIP2) Lipids in Asymmetric Lipid Bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:1732-1741. [PMID: 26829708 DOI: 10.1021/acs.langmuir.5b02814] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Phosphatidylinositol phosphate (PIP) lipids are critical to many cell signaling pathways, in part by acting as molecular beacons that recruit peripheral membrane proteins to specific locations within the plasma membrane. Understanding the biophysics of PIP-protein interactions is critical to developing a chemically detailed model of cell communication. Resolving such interactions is challenging, even in model membrane systems, because of the difficulty in preparing PIP-containing membranes with high fluidity and integrity. Here we report on a simple, vesicle-based protocol for preparing asymmetric supported lipid bilayers in which fluorescent PIP lipid analogues are found only on the top leaflet of the supported membrane facing the bulk solution. With this asymmetric distribution of lipids between the leaflets, the fluorescent signal from the PIP lipid analogue reports directly on interactions between the peripheral molecules and the top leaflet of the membrane. Asymmetric PIP-containing bilayers are an ideal platform to investigate the interaction of PIP with peripheral membrane proteins using fluorescence-based imaging approaches. We demonstrate their usefulness here with a combined fluorescence correlation spectroscopy and single particle tracking study of the interaction between PIP2 lipids and a polycationic polymer, quaternized polyvinylpyridine (QPVP). With this approach we are able to quantify the microscopic features of the mobility coupling between PIP2 lipids and polybasic QPVP. With single particle tracking we observe individual PIP2 lipids switch from Brownian to intermittent motion as they become transiently trapped by QPVP.
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Affiliation(s)
| | | | - Xiaodong Zhuang
- Institute of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University , 315 Jiangong Building, 800 Dongchuan Road, Shanghai 200240, China
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26
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Ludolphs M, Schneeberger D, Soykan T, Schäfer J, Papadopoulos T, Brose N, Schindelin H, Steinem C. Specificity of Collybistin-Phosphoinositide Interactions: IMPACT OF THE INDIVIDUAL PROTEIN DOMAINS. J Biol Chem 2015; 291:244-54. [PMID: 26546675 DOI: 10.1074/jbc.m115.673400] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Indexed: 01/01/2023] Open
Abstract
The regulatory protein collybistin (CB) recruits the receptor-scaffolding protein gephyrin to mammalian inhibitory glycinergic and GABAergic postsynaptic membranes in nerve cells. CB is tethered to the membrane via phosphoinositides. We developed an in vitro assay based on solid-supported 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine membranes doped with different phosphoinositides on silicon/silicon dioxide substrates to quantify the binding of various CB2 constructs using reflectometric interference spectroscopy. Based on adsorption isotherms, we obtained dissociation constants and binding capacities of the membranes. Our results show that full-length CB2 harboring the N-terminal Src homology 3 (SH3) domain (CB2SH3+) adopts a closed and autoinhibited conformation that largely prevents membrane binding. This autoinhibition is relieved upon introduction of the W24A/E262A mutation, which conformationally "opens" CB2SH3+ and allows the pleckstrin homology domain to properly bind lipids depending on the phosphoinositide species with a preference for phosphatidylinositol 3-monophosphate and phosphatidylinositol 4-monophosphate. This type of membrane tethering under the control of the release of the SH3 domain of CB is essential for regulating gephyrin clustering.
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Affiliation(s)
- Michaela Ludolphs
- From the Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany
| | - Daniela Schneeberger
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Josef-Schneider-Strasse 2, 97080 Würzburg, Germany
| | - Tolga Soykan
- Department of Molecular Neurobiology, Max Planck Institute for Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany, and
| | - Jonas Schäfer
- From the Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany
| | - Theofilos Papadopoulos
- Universitätsmedizin Göttingen, Department of Molecular Biology, Humboldtallee 23, 37073 Göttingen, Germany
| | - Nils Brose
- Department of Molecular Neurobiology, Max Planck Institute for Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany, and
| | - Hermann Schindelin
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Josef-Schneider-Strasse 2, 97080 Würzburg, Germany
| | - Claudia Steinem
- From the Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany,
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27
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Drücker P, Pejic M, Grill D, Galla HJ, Gerke V. Cooperative binding of annexin A2 to cholesterol- and phosphatidylinositol-4,5-bisphosphate-containing bilayers. Biophys J 2015; 107:2070-81. [PMID: 25418092 DOI: 10.1016/j.bpj.2014.08.027] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 08/14/2014] [Accepted: 08/27/2014] [Indexed: 10/24/2022] Open
Abstract
Biological membranes are organized into dynamic microdomains that serve as sites for signal transduction and membrane trafficking. The formation and expansion of these microdomains are driven by intrinsic properties of membrane lipids and integral as well as membrane-associated proteins. Annexin A2 (AnxA2) is a peripherally associated membrane protein that can support microdomain formation in a Ca(2+)-dependent manner and has been implicated in membrane transport processes. Here, we performed a quantitative analysis of the binding of AnxA2 to solid supported membranes containing the annexin binding lipids phosphatidylinositol-4,5-bisphosphate and phosphatidylserine in different compositions. We show that the binding is of high specificity and affinity with dissociation constants ranging between 22.1 and 32.2 nM. We also analyzed binding parameters of a heterotetrameric complex of AnxA2 with its S100A10 protein ligand and show that this complex has a higher affinity for the same membranes with Kd values of 12 to 16.4 nM. Interestingly, binding of the monomeric AnxA2 and the AnxA2-S100A10 complex are characterized by positive cooperativity. This cooperative binding is mediated by the conserved C-terminal annexin core domain of the protein and requires the presence of cholesterol. Together our results reveal for the first time, to our knowledge, that AnxA2 and its derivatives bind cooperatively to membranes containing cholesterol, phosphatidylserine, and/or phosphatidylinositol-4,5-bisphosphate, thus providing a mechanistic model for the lipid clustering activity of AnxA2.
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Affiliation(s)
- Patrick Drücker
- Institute of Biochemistry, University of Muenster, Muenster, Germany
| | - Milena Pejic
- Institute of Medical Biochemistry, ZMBE, University of Muenster, Muenster, Germany
| | - David Grill
- Institute of Medical Biochemistry, ZMBE, University of Muenster, Muenster, Germany
| | | | - Volker Gerke
- Institute of Medical Biochemistry, ZMBE, University of Muenster, Muenster, Germany.
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28
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Harishchandra RK, Neumann BM, Gericke A, Ross AH. Biophysical methods for the characterization of PTEN/lipid bilayer interactions. Methods 2015; 77-78:125-35. [PMID: 25697761 PMCID: PMC4388815 DOI: 10.1016/j.ymeth.2015.02.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Revised: 02/09/2015] [Accepted: 02/10/2015] [Indexed: 12/22/2022] Open
Abstract
PTEN, a tumor suppressor protein that dephosphorylates phosphoinositides at the 3-position of the inositol ring, is a cytosolic protein that needs to associate with the plasma membrane or other subcellular membranes to exert its lipid phosphatase function. Upon membrane association PTEN interacts with at least three different lipid entities: An anionic lipid that is present in sufficiently high concentration to create a negative potential that allows PTEN to interact electrostatically with the membrane, phosphatidylinositol-4,5-bisphosphate, which interacts with PTEN's N-terminal end and the substrate, usually phosphatidylinositol-3,4,5-trisphosphate. Many parameters influence PTEN's interaction with the lipid bilayer, for example, the lateral organization of the lipids or the presence of other chemical species like cholesterol or other lipids. To investigate systematically the different steps of PTEN's complex binding mechanism and to explore its dynamic behavior in the membrane bound state, in vitro methods need to be employed that allow for a systematic variation of the experimental conditions. In this review we survey a variety of methods that can be used to assess PTEN lipid binding affinity, the dynamics of its membrane association as well as its dynamic behavior in the membrane bound state.
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Affiliation(s)
- Rakesh K Harishchandra
- Worcester Polytechnic Institute, Department of Chemistry and Biochemistry, Worcester, MA 01605, USA
| | - Brittany M Neumann
- Worcester Polytechnic Institute, Department of Chemistry and Biochemistry, Worcester, MA 01605, USA
| | - Arne Gericke
- Worcester Polytechnic Institute, Department of Chemistry and Biochemistry, Worcester, MA 01605, USA
| | - Alonzo H Ross
- University of Massachusetts Medical School, Department of Biochemistry and Molecular Pharmacology, Worcester, MA 01605, USA.
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29
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Shi X, Li X, Kaliszewski MJ, Zhuang X, Smith AW. Tuning the mobility coupling of quaternized polyvinylpyridine and anionic phospholipids in supported lipid bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:1784-1791. [PMID: 25599116 DOI: 10.1021/la504241w] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Binding of biomacromolecules to anionic lipids in the plasma membrane is a common motif in many cell signaling pathways. Previous work has shown that macromolecules with cationic sequences can form nanodomains with sequestered anionic lipids, which alters the lateral distribution and mobility of the membrane lipids. Such sequestration is believed to result from the formation of a lipid-macromolecule complex. To date, however, the molecular structure and dynamics of the lipid-polymer interface are poorly understood. We have investigated the behavior of polycationic quaternized polyvinylpyridine (QPVP) on supported lipid bilayers doped with phosphatidylserine (PS) or phosphatidylinositol phosphate (PIP) lipids using time-resolved fluorescence microscopy, including pulsed interleaved excitation fluorescence cross-correlation spectroscopy (PIE-FCCS). PIE-FCCS is a dual-color fluorescence spectroscopy that translates fluctuations in fluorescence signal into a measurement of diffusion and colocalization. By labeling the polymer and lipids, we investigated the adsorption-induced translational mobility of lipids and systematically studied the influence of lipid charge density and solution ionic strength. Our results show that alteration of anionic lipid lateral mobility is dependent on the net charge of the lipid headgroup and is modulated by the ionic strength of the solution, indicating that electrostatic interactions drive the decrease in lateral mobility of anionic lipids by adsorbed QPVP. At physiological salt concentration we observe that the lipid lateral mobility is weakly influenced by QPVP and that there is no evidence of stable lipid-polymer complexes.
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Affiliation(s)
- Xiaojun Shi
- Department of Chemistry, The University of Akron , 190 Buchtel Common, Akron, Ohio 44325-3601, United States
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30
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Drücker P, Grill D, Gerke V, Galla HJ. Formation and characterization of supported lipid bilayers containing phosphatidylinositol-4,5-bisphosphate and cholesterol as functional surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:14877-14886. [PMID: 25415330 DOI: 10.1021/la503203a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Solid-supported lipid bilayers (SLBs) mimicking a biological membrane are commonly used to investigate lipid-lipid or lipid-protein interactions. Simple binary or ternary lipid systems are well established, whereas more complex model membranes containing biologically important signaling lipids such as phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2) and cholesterol have not been extensively described yet. Here we report the generation of such bilayers and their relevant biophysical properties and in particular the accessibility of PI(4,5)P2 for protein binding. Ternary mixtures of POPC with 20% cholesterol and either 3 or 5 mol % dioleoyl-phosphatidylinositol-4,5-bisphosphate were probed by employing the quartz crystal microbalance and atomic force microscopy. We show that these mixtures form homogeneous solid-supported bilayers that exhibit no intrinsic phase separation and are characterized by long-term stability (>8 h). Bilayers were formed in a pH-dependent manner and were characterized by the accessibility of PI(4,5)P2 on the SLB surface as shown by the interaction with the PI(4,5)P2 binding domain of the cortical membrane-cytoskeleton linker protein ezrin. A time-dependent reduction of PI(4,5)P2 levels in the upper leaflet of SLBs was observed, which could be effectively inhibited by the incorporation of a negatively charged lipid such as phosphatidylserine. Furthermore, quartz crystal microbalance measurements revealed that cholesterol affects bilayer adsorption to the solid support.
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Affiliation(s)
- Patrick Drücker
- Institute of Biochemistry and ‡Institute of Medical Biochemistry, ZMBE, University of Münster , D-48149 Münster, Germany
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31
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Drücker P, Gerke V, Galla HJ. Importance of phospholipid bilayer integrity in the analysis of protein-lipid interactions. Biochem Biophys Res Commun 2014; 453:143-7. [PMID: 25264195 DOI: 10.1016/j.bbrc.2014.09.079] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 09/18/2014] [Indexed: 11/29/2022]
Abstract
The integrity of supported phospholipid bilayer membranes is of crucial importance for the investigation of lipid-protein interactions. Therefore we recorded the formation of supported membranes on SiO2 and mica by quartz crystal microbalance and controlled the integrity by atomic force microscopy. This study aims to analyze how membrane defects affect protein-lipid interactions. The experiments focused on a lipid mixture of POPC/DOPC/Chol/POPS/PI(4,5)P2 (37:20:20:20:3) and the binding of the peripheral membrane associated protein annexin A2. We found that formation of a continuous undisturbed bilayer is an indispensable precondition for a reliable determination and quantification of lipid-protein-interactions. If membrane defects were present, protein adsorption causes membrane disruption and lipid detachment on a support thus leading to false determination of binding constants. Our results obtained for PI(4,5)P2 and cholesterol containing supported membranes yield new knowledge to construct functional surfaces that may cover nanoporous substrates, form free standing membranes or may be used for lab-on-a-chip applications.
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Affiliation(s)
- Patrick Drücker
- Institute of Biochemistry, University of Münster, Wilhelm-Klemm-Str. 2, D-48149 Münster, Germany
| | - Volker Gerke
- Institute of Medical Biochemistry, ZMBE, University of Münster, Von-Esmarch-Str. 56, D-48149 Münster, Germany
| | - Hans-Joachim Galla
- Institute of Biochemistry, University of Münster, Wilhelm-Klemm-Str. 2, D-48149 Münster, Germany.
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32
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Slochower DR, Wang YH, Tourdot RW, Radhakrishnan R, Janmey PA. Counterion-mediated pattern formation in membranes containing anionic lipids. Adv Colloid Interface Sci 2014; 208:177-88. [PMID: 24556233 DOI: 10.1016/j.cis.2014.01.016] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 01/21/2014] [Accepted: 01/22/2014] [Indexed: 01/05/2023]
Abstract
Most lipid components of cell membranes are either neutral, like cholesterol, or zwitterionic, like phosphatidylcholine and sphingomyelin. Very few lipids, such as sphingosine, are cationic at physiological pH. These generally interact only transiently with the lipid bilayer, and their synthetic analogs are often designed to destabilize the membrane for drug or DNA delivery. However, anionic lipids are common in both eukaryotic and prokaryotic cell membranes. The net charge per anionic phospholipid ranges from -1 for the most abundant anionic lipids such as phosphatidylserine, to near -7 for phosphatidylinositol 3,4,5 trisphosphate, although the effective charge depends on many environmental factors. Anionic phospholipids and other negatively charged lipids such as lipopolysaccharides are not randomly distributed in the lipid bilayer, but are highly restricted to specific leaflets of the bilayer and to regions near transmembrane proteins or other organized structures within the plane of the membrane. This review highlights some recent evidence that counterions, in the form of monovalent or divalent metal ions, polyamines, or cationic protein domains, have a large influence on the lateral distribution of anionic lipids within the membrane, and that lateral demixing of anionic lipids has effects on membrane curvature and protein function that are important for biological control.
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Affiliation(s)
- David R Slochower
- Graduate Group in Biochemistry and Molecular Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Yu-Hsiu Wang
- Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Richard W Tourdot
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ravi Radhakrishnan
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Paul A Janmey
- Graduate Group in Biochemistry and Molecular Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Departments of Physiology and Physics, University of Pennsylvania, Philadelphia, PA 19104, USA
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33
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Jiang Z, Redfern RE, Isler Y, Ross AH, Gericke A. Cholesterol stabilizes fluid phosphoinositide domains. Chem Phys Lipids 2014; 182:52-61. [PMID: 24556334 DOI: 10.1016/j.chemphyslip.2014.02.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 02/06/2014] [Accepted: 02/07/2014] [Indexed: 11/19/2022]
Abstract
Local accumulation of phosphoinositides (PIPs) is an important factor for a broad range of cellular events including membrane trafficking and cell signaling. The negatively charged phosphoinositide headgroups can interact with cations or cationic proteins and this electrostatic interaction has been identified as the main phosphoinositide clustering mechanism. However, an increasing number of reports show that phosphoinositide-mediated signaling events are at least in some cases cholesterol dependent, suggesting other possible contributors to the segregation of phosphoinositides. Using fluorescence microscopy on giant unilamellar vesicles and monolayers at the air/water interface, we present data showing that cholesterol stabilizes fluid phosphoinositide-enriched phases. The interaction with cholesterol is observed for all investigated phosphoinositides (PI(4)P, PI(3,4)P2, PI(3,5)P2, PI(4,5)P2 and PI(3,4,5)P3) as well as phosphatidylinositol. We find that cholesterol is present in the phosphoinositide-enriched phase and that the resulting phase is fluid. Cholesterol derivatives modified at the hydroxyl group (cholestenone, cholesteryl ethyl ether) do not promote formation of phosphoinositide domains, suggesting an instrumental role of the cholesterol hydroxyl group in the observed cholesterol/phosphoinositide interaction. This leads to the hypothesis that cholesterol participates in an intermolecular hydrogen bond network formed among the phosphoinositide lipids. We had previously reported that the intra- and intermolecular hydrogen bond network between the phosphoinositide lipids leads to a reduction of the charge density at the phosphoinositide phosphomonoester groups (Kooijman et al., 2009). We believe that cholesterol acts as a spacer between the phosphoinositide lipids, thereby reducing the electrostatic repulsion, while participating in the hydrogen bond network, leading to its further stabilization. To illustrate the effect of phosphoinositide segregation on protein binding, we show that binding of the tumor suppressor protein PTEN to PI(5)P and PI(4,5)P2 is enhanced in the presence of cholesterol. These results provide new insights into how phosphoinositides mediate important cellular events.
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Affiliation(s)
- Zhiping Jiang
- Laboratory of Molecular Biophysics, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, United States
| | - Roberta E Redfern
- ProMedica Research Department, ProMedica Health System, Toledo, OH 43606, United States
| | - Yasmin Isler
- Academic Health Center BioRepository, ProMedica Health System, Toledo, OH 43606, United States
| | - Alonzo H Ross
- University of Massachusetts Medical School, Worcester, MA 01605, United States
| | - Arne Gericke
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA 01609, United States.
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34
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Graber ZT, Gericke A, Kooijman EE. Phosphatidylinositol-4,5-bisphosphate ionization in the presence of cholesterol, calcium or magnesium ions. Chem Phys Lipids 2013; 182:62-72. [PMID: 24309195 DOI: 10.1016/j.chemphyslip.2013.11.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Accepted: 11/13/2013] [Indexed: 10/26/2022]
Abstract
Phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2) is an important signaling lipid and plays a crucial role in a wide variety of cellular processes by interacting with protein targets and localizing proteins at the plasma membrane. These interactions are strongly influenced by the lateral distribution of PI(4,5)P2 as well as its ionization state. The characterization of the PI(4,5)P2 ionization state provides important information about how PI(4,5)P2 interacts with other membrane resident or associated chemical species. In this study we have used solid-state MAS (31)P NMR to investigate the interactions of PI(4,5)P2 with potential cluster promoting agents, divalent cations and cholesterol. Both Ca(2+) and cholesterol were found previously to promote formation of local PI(4,5)P2 clusters in vitro. The NMR approach allows us to probe independently the ionization state of PI(4,5)P2 two phosphomonoester groups. We investigated mixed phosphatidylcholine (PC)/PI(4,5)P2 multilamellar vesicles in the presence of micro and millimolar concentrations of Ca(2+) and Mg(2+). We found that both cations lead to an increased downfield chemical shift of the PI(4,5)P2 phosphomonoester peaks, indicating an increased ionization in the presence of the divalent cations. Ca(2+) has a much larger effect on PI(4,5)P2 as compared to Mg(2+) at similar concentrations. Physiological concentrations of Ca(2+) are significantly lower than those found for Mg(2+) and the comparison of the PI(4,5)P2 ionization in the presence of Ca(2+) and Mg(2+) at physiological concentrations resulted in similar charges of the phosphomonoester groups for both cations. PI(4,5)P2 was also examined with vesicles containing cholesterol since cholesterol has been shown to promote PI(4,5)P2 clustering. In the presence of 40 mol% cholesterol, the PI(4,5)P2 phosphomonoester (31)P NMR peaks shifted slightly downfield, indicating a small increase in charge. Previously published data suggest that PI(4,5)P2 is capable of forming an intra- and intermolecular hydrogen bond network, which leads to a reduction of the charge at the phosphomonoester groups through dissipation of the charge across the bilayer/water interface. We hypothesize that cholesterol participates in this intermolecular hydrogen bond network, resulting in a stabilization of PI(4,5)P2 enriched domains due an increased spacing between the PI(4,5)P2 headgroup. We also examined the cumulative effects of cholesterol combined with the divalent cations, phosphatidylethanolamine (PE), and phosphatidylinositol (PI), separately. The combination of cholesterol and divalent cations results in an additive effect on PI(4,5)P2 ionization, while the effect of cholesterol on PI(4,5)P2 ionization is reduced in the presence of PE or PI.
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Affiliation(s)
- Zachary T Graber
- Kent State University, Department of Chemistry and Biochemistry, PO Box 5190, Kent, OH 44242, USA
| | - Arne Gericke
- Worcester Polytechnic Institute, Department of Chemistry and Biochemistry, 100 Institute Road, Worcester, MA 01605, USA
| | - Edgar E Kooijman
- Kent State University, Department of Biological Sciences, PO Box 5190, Kent, OH 44242, USA.
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