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Weakly HMJ, Keller SL. Coupling liquid phases in 3D condensates and 2D membranes: Successes, challenges, and tools. Biophys J 2024; 123:1329-1341. [PMID: 38160256 PMCID: PMC11163299 DOI: 10.1016/j.bpj.2023.12.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 12/05/2023] [Accepted: 12/26/2023] [Indexed: 01/03/2024] Open
Abstract
This review describes the major experimental challenges researchers meet when attempting to couple phase separation between membranes and condensates. Although it is well known that phase separation in a 2D membrane could affect molecules capable of forming a 3D condensate (and vice versa), few researchers have quantified the effects to date. The scarcity of these measurements is not due to a lack of intense interest or effort in the field. Rather, it reflects significant experimental challenges in manipulating coupled membranes and condensates to yield quantitative values. These challenges transcend many molecular details, which means they impact a wide range of systems. This review highlights recent exciting successes in the field, and it lays out a comprehensive list of tools that address potential pitfalls for researchers who are considering coupling membranes with condensates.
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Affiliation(s)
- Heidi M J Weakly
- Department of Chemistry, University of Washington - Seattle, Seattle, Washington
| | - Sarah L Keller
- Department of Chemistry, University of Washington - Seattle, Seattle, Washington.
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2
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Nehls C, Schröder M, Haubenthal T, Haas A, Gutsmann T. The mechanistic basis of the membrane-permeabilizing activities of the virulence-associated protein A (VapA) from Rhodococcus equi. Mol Microbiol 2024; 121:578-592. [PMID: 38308564 DOI: 10.1111/mmi.15233] [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: 06/20/2023] [Revised: 01/12/2024] [Accepted: 01/17/2024] [Indexed: 02/05/2024]
Abstract
Pathogenic Rhodococcus equi release the virulence-associated protein A (VapA) within macrophage phagosomes. VapA permeabilizes phagosome and lysosome membranes and reduces acidification of both compartments. Using biophysical techniques, we found that VapA interacts with model membranes in four steps: (i) binding, change of mechanical properties, (ii) formation of specific membrane domains, (iii) permeabilization within the domains, and (iv) pH-specific transformation of domains. Biosensor data revealed that VapA binds to membranes in one step at pH 6.5 and in two steps at pH 4.5 and decreases membrane fluidity. The integration of VapA into lipid monolayers was only significant at lateral pressures <20 mN m-1 indicating preferential incorporation into membrane regions with reduced integrity. Atomic force microscopy of lipid mono- and bilayers showed that VapA increased the surface heterogeneity of liquid disordered domains. Furthermore, VapA led to the formation of a new microstructured domain type and, at pH 4.5, to the formation of 5 nm high domains. VapA binding, its integration and lipid domain formation depended on lipid composition, pH, protein concentration and lateral membrane pressure. VapA-mediated permeabilization is clearly distinct from that caused by classical microbial pore formers and is a key contribution to the multiplication of Rhodococcus equi in phagosomes.
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Affiliation(s)
- Christian Nehls
- Division of Biophysics, Research Center Borstel - Leibniz Lung Center, Borstel, Germany
- Centre for Structural Systems Biology (CSSB), Hamburg, Germany
- Kiel Nano, Surface and Interface Science KiNSIS, Kiel University, Kiel, Germany
| | - Marcel Schröder
- Division of Biophysics, Research Center Borstel - Leibniz Lung Center, Borstel, Germany
| | | | - Albert Haas
- Cell Biology Institute, University of Bonn, Bonn, Germany
| | - Thomas Gutsmann
- Division of Biophysics, Research Center Borstel - Leibniz Lung Center, Borstel, Germany
- Centre for Structural Systems Biology (CSSB), Hamburg, Germany
- Kiel Nano, Surface and Interface Science KiNSIS, Kiel University, Kiel, Germany
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3
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Hegaard FV, Klenow MB, Simonsen AC. Lens Nucleation and Droplet Budding in a Membrane Model for Lipid Droplet Biogenesis. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:9247-9256. [PMID: 35849366 DOI: 10.1021/acs.langmuir.2c01014] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Lipid droplet biogenesis comprises the emergence of cytosolic lipid droplets with a typical diameter 0.1-5 μm via synthesis of fat in the endoplasmatic reticulum, the formation of membrane-embedded lenses, and the eventual budding of lenses into solution as droplets. Lipid droplets in cells are increasingly being viewed as highly dynamic organelles with multiple functions in cell physiology. However, the mechanism of droplet formation in cells remains poorly understood, partly because their formation involves the rapid transformation of transient lipid structures that are difficult to capture. Thus, the development of controlled experimental systems that model lipid biogenesis is highly relevant for an enhanced mechanistic understanding. Here we prepare and characterize triolein (TO) lenses in a multilamellar spin-coated phosphatidylcholine (POPC) film and determine the lens nucleation threshold to 0.25-0.5% TO. The TO lens shapes are characterized by atomic force microscopy (AFM) including their mean cap angle ⟨α⟩ = 27.3° and base radius ⟨a⟩ = 152.7 nm. A cross-correlation analysis of corresponding AFM and fluorescence images confirms that TO is localized to lenses. Hydration of the lipid/lens film induces the gel to fluid membrane phase transition and makes the lenses more mobile. The budding of free droplets into solution from membrane lenses is detected by observing a change in motion from confined wiggling to ballistic motion of droplets in solution. The results confirm that droplet budding can occur spontaneously without being facilitated by proteins. The developed model system provides a controlled platform for testing mechanisms of lipid droplet biogenesis in vitro and addressing questions related to lens formation and droplet budding by quantitative image analysis.
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Affiliation(s)
- Frederik Viktor Hegaard
- Department of Physics, Chemistry and Pharmacy (FKF), PhyLife - Physical LifeScience, University of Southern Denmark (SDU), Campusvej 55, 5230 Odense M, Denmark
| | - Martin Berg Klenow
- Department of Physics, Chemistry and Pharmacy (FKF), PhyLife - Physical LifeScience, University of Southern Denmark (SDU), Campusvej 55, 5230 Odense M, Denmark
| | - Adam Cohen Simonsen
- Department of Physics, Chemistry and Pharmacy (FKF), PhyLife - Physical LifeScience, University of Southern Denmark (SDU), Campusvej 55, 5230 Odense M, Denmark
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4
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Socrier L, Bail C, Ackermann E, Beresowski AK, Ahadi S, Werz DB, Steinem C. The Interaction of Gb 3 Glycosphingolipids with ld and lo Phase Lipids in Lipid Monolayers Is a Function of Their Fatty Acids. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:5874-5882. [PMID: 35439015 DOI: 10.1021/acs.langmuir.2c00497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The glycosphingolipid Gb3 is a specific receptor of the bacterial Shiga toxin (STx). Binding of STx to Gb3 is a prerequisite for its internalization into the host cells, and the ceramide's fatty acid of Gb3 has been shown to influence STx binding. In in vitro studies on liquid ordered (lo)/liquid disordered (ld) coexisting artificial membranes, Shiga toxin B (STxB) binds solely to lo domains, thus harboring Gb3 concomitant with an observed lipid redistribution process. These findings raise the question of how the molecular structure of the fatty acid of Gb3 influences the interaction of Gb3 with the different lipids preferentially either found in the lo phase, namely, sphingomyelin and cholesterol, or in the ld phase. We addressed this question by using a series of synthetically available and unlabeled Gb3 glycosphingolipids carrying different long chain C24 fatty acids (saturated, monounsaturated, and α-hydroxylated). In conjunction with surface tension experiments on Langmuir monolayers, we quantified the excess of free energy of mixing of the different Gb3 species in monolayers composed of either sphingomyelin or cholesterol or composed of a fluid phase lipid (DOPC). From a calculation of the total free energy of mixing, we conclude that mixing of the saturated Gb3 species with the ld lipid DOPC is energetically less favorable than all other combinations, while the unsaturated species mix equally well with the lo phase lipids sphingomyelin and cholesterol and the ld phase lipid DOPC. Furthermore, we found that STxB partially penetrates in mixed lipid monolayers (DOPC/sphingomyelin/cholesterol) containing the Gb3 sphingolipid with a saturated or a monounsaturated C24 fatty acid. The maximum insertion pressure, as a measure for protein insertion, is >30 mN/m for both Gb3 molecules and is not significantly different for the two Gb3 species.
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Affiliation(s)
- Larissa Socrier
- Max-Planck-Institute for Dynamics and Self-Organization, Am Fassberg 17, 37077 Göttingen, Germany
- Institute of Organic and Biomolecular Chemistry, Georg-August-Universität, Tammannstraße 2, 37077 Göttingen, Germany
| | - Céline Bail
- Institute of Organic and Biomolecular Chemistry, Georg-August-Universität, Tammannstraße 2, 37077 Göttingen, Germany
| | - Elena Ackermann
- Institute of Organic and Biomolecular Chemistry, Georg-August-Universität, Tammannstraße 2, 37077 Göttingen, Germany
| | - Ann-Kathrin Beresowski
- Institute of Organic and Biomolecular Chemistry, Georg-August-Universität, Tammannstraße 2, 37077 Göttingen, Germany
| | - Somayeh Ahadi
- Institute of Organic Chemistry, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany
| | - Daniel B Werz
- Institute of Organic Chemistry, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany
| | - Claudia Steinem
- Max-Planck-Institute for Dynamics and Self-Organization, Am Fassberg 17, 37077 Göttingen, Germany
- Institute of Organic and Biomolecular Chemistry, Georg-August-Universität, Tammannstraße 2, 37077 Göttingen, Germany
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5
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Nadeem A, Berg A, Pace H, Alam A, Toh E, Ådén J, Zlatkov N, Myint SL, Persson K, Gröbner G, Sjöstedt A, Bally M, Barandun J, Uhlin BE, Wai SN. Protein-lipid interaction at low pH induces oligomerization of the MakA cytotoxin from Vibrio cholerae. eLife 2022; 11:73439. [PMID: 35131030 PMCID: PMC8824476 DOI: 10.7554/elife.73439] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Accepted: 01/19/2022] [Indexed: 12/29/2022] Open
Abstract
The α-pore-forming toxins (α-PFTs) from pathogenic bacteria damage host cell membranes by pore formation. We demonstrate a remarkable, hitherto unknown mechanism by an α-PFT protein from Vibrio cholerae. As part of the MakA/B/E tripartite toxin, MakA is involved in membrane pore formation similar to other α-PFTs. In contrast, MakA in isolation induces tube-like structures in acidic endosomal compartments of epithelial cells in vitro. The present study unravels the dynamics of tubular growth, which occurs in a pH-, lipid-, and concentration-dependent manner. Within acidified organelle lumens or when incubated with cells in acidic media, MakA forms oligomers and remodels membranes into high-curvature tubes leading to loss of membrane integrity. A 3.7 Å cryo-electron microscopy structure of MakA filaments reveals a unique protein-lipid superstructure. MakA forms a pinecone-like spiral with a central cavity and a thin annular lipid bilayer embedded between the MakA transmembrane helices in its active α-PFT conformation. Our study provides insights into a novel tubulation mechanism of an α-PFT protein and a new mode of action by a secreted bacterial toxin.
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Affiliation(s)
- Aftab Nadeem
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
| | - Alexandra Berg
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden.,Science for Life Laboratory (SciLifeLab), Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Hudson Pace
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,Department of Clinical Microbiology, Umeå University, Umeå, Sweden.,Wallenberg Centre for Molecular Medicine, Umeå University, Umeå, Sweden
| | - Athar Alam
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden.,Department of Clinical Microbiology, Umeå University, Umeå, Sweden
| | - Eric Toh
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
| | - Jörgen Ådén
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,Department of Chemistry, Umeå University, Umeå, Sweden
| | - Nikola Zlatkov
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
| | - Si Lhyam Myint
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
| | - Karina Persson
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,Department of Chemistry, Umeå University, Umeå, Sweden
| | - Gerhard Gröbner
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,Department of Chemistry, Umeå University, Umeå, Sweden
| | - Anders Sjöstedt
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden.,Department of Clinical Microbiology, Umeå University, Umeå, Sweden
| | - Marta Bally
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,Department of Clinical Microbiology, Umeå University, Umeå, Sweden.,Wallenberg Centre for Molecular Medicine, Umeå University, Umeå, Sweden
| | - Jonas Barandun
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
| | - Bernt Eric Uhlin
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
| | - Sun Nyunt Wai
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
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6
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Ho JCS, Su WC, Chun Wang X, Parikh AN, Liedberg B. Nonequilibrium Self-Organization of Lipids into Hierarchically Ordered and Compositionally Graded Cylindrical Smectics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:1045-1056. [PMID: 35020400 DOI: 10.1021/acs.langmuir.1c02576] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
When a dry mass of certain amphiphiles encounters water, a spectacular interfacial instability ensues: It gives rise to the formation of ensembles of fingerlike tubular protrusions called myelin figures─tens of micrometers wide and tens to hundreds of micrometers long─representing a novel class of nonequilibrium higher-order self-organization. Here, we report that when phase-separating mixtures of unsaturated lipid, cholesterol, and sphingomyelin are hydrated, the resulting myelins break symmetry and couple their compositional degrees of freedom with the extended myelinic morphology: They produce complementary, interlamellar radial gradients of concentrations of cholesterol (and sphingomyelin) and unsaturated lipid, which stands in stark contrast to interlamellar, lateral phase separation in equilibrated morphologies. Furthermore, the corresponding gradients of molecule-specific chemistries (i.e., cholesterol extraction by methyl-β-cyclodextrin and GM1 binding by cholera toxin) produce unusual morphologies comprising compositionally graded vesicles and buckled tubes. We propose that kinetic differences in the information processing of hydration characteristics of individual molecules while expending energy dictate this novel behavior of lipid mixtures undergoing hydration.
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Affiliation(s)
- James C S Ho
- Centre for Biomimetic Sensor Science, Nanyang Technological University, 50 Nanyang Drive, 637553 Singapore
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore
| | | | - Xuan Chun Wang
- Centre for Biomimetic Sensor Science, Nanyang Technological University, 50 Nanyang Drive, 637553 Singapore
| | - Atul N Parikh
- Centre for Biomimetic Sensor Science, Nanyang Technological University, 50 Nanyang Drive, 637553 Singapore
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore
| | - Bo Liedberg
- Centre for Biomimetic Sensor Science, Nanyang Technological University, 50 Nanyang Drive, 637553 Singapore
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore
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7
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Pezeshkian W, Shillcock JC, Ipsen JH. Computational Approaches to Explore Bacterial Toxin Entry into the Host Cell. Toxins (Basel) 2021; 13:toxins13070449. [PMID: 34203472 PMCID: PMC8309782 DOI: 10.3390/toxins13070449] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 06/18/2021] [Accepted: 06/23/2021] [Indexed: 01/13/2023] Open
Abstract
Many bacteria secrete toxic protein complexes that modify and disrupt essential processes in the infected cell that can lead to cell death. To conduct their action, these toxins often need to cross the cell membrane and reach a specific substrate inside the cell. The investigation of these protein complexes is essential not only for understanding their biological functions but also for the rational design of targeted drug delivery vehicles that must navigate across the cell membrane to deliver their therapeutic payload. Despite the immense advances in experimental techniques, the investigations of the toxin entry mechanism have remained challenging. Computer simulations are robust complementary tools that allow for the exploration of biological processes in exceptional detail. In this review, we first highlight the strength of computational methods, with a special focus on all-atom molecular dynamics, coarse-grained, and mesoscopic models, for exploring different stages of the toxin protein entry mechanism. We then summarize recent developments that are significantly advancing our understanding, notably of the glycolipid–lectin (GL-Lect) endocytosis of bacterial Shiga and cholera toxins. The methods discussed here are also applicable to the design of membrane-penetrating nanoparticles and the study of the phenomenon of protein phase separation at the surface of the membrane. Finally, we discuss other likely routes for future development.
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Affiliation(s)
- Weria Pezeshkian
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, 9712 Groningen, The Netherlands
- Correspondence:
| | - Julian C. Shillcock
- Blue Brain Project, Laboratory of Molecular and Chemical Biology of Neurodegeneration, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland;
| | - John H. Ipsen
- MEMPHYS/PhyLife, Department of Physics, Chemistry and Pharmacy (FKF), University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark;
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8
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Uusitalo M, Klenow MB, Laulumaa S, Blakeley MP, Simonsen AC, Ruskamo S, Kursula P. Human myelin protein P2: from crystallography to time-lapse membrane imaging and neuropathy-associated variants. FEBS J 2021; 288:6716-6735. [PMID: 34138518 DOI: 10.1111/febs.16079] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 06/10/2021] [Accepted: 06/16/2021] [Indexed: 12/11/2022]
Abstract
Peripheral myelin protein 2 (P2) is a fatty acid-binding protein expressed in vertebrate peripheral nervous system myelin, as well as in human astrocytes. Suggested functions of P2 include membrane stacking and lipid transport. Mutations in the PMP2 gene, encoding P2, are associated with Charcot-Marie-Tooth disease (CMT). Recent studies have revealed three novel PMP2 mutations in CMT patients. To shed light on the structure and function of these P2 variants, we used X-ray and neutron crystallography, small-angle X-ray scattering, circular dichroism spectroscopy, computer simulations and lipid binding assays. The crystal and solution structures of the I50del, M114T and V115A variants of P2 showed minor differences to the wild-type protein, whereas their thermal stability was reduced. Vesicle aggregation assays revealed no change in membrane stacking characteristics, while the variants showed altered fatty acid binding. Time-lapse imaging of lipid bilayers indicated formation of double-membrane structures induced by P2, which could be related to its function in stacking of two myelin membrane surfaces in vivo. In order to better understand the links between structure, dynamics and function, the crystal structure of perdeuterated P2 was refined from room temperature data using neutrons and X-rays, and the results were compared to simulations and cryocooled crystal structures. Our data indicate similar properties for all known human P2 CMT variants; while crystal structures are nearly identical, thermal stability and function of CMT variants are impaired. Our data provide new insights into the structure-function relationships and dynamics of P2 in health and disease.
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Affiliation(s)
- Maiju Uusitalo
- Faculty of Biochemistry and Molecular Medicine & Biocenter Oulu, University of Oulu, Finland
| | - Martin Berg Klenow
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense, Denmark
| | - Saara Laulumaa
- Faculty of Biochemistry and Molecular Medicine & Biocenter Oulu, University of Oulu, Finland.,European Spallation Source, Lund, Sweden
| | | | - Adam Cohen Simonsen
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense, Denmark
| | - Salla Ruskamo
- Faculty of Biochemistry and Molecular Medicine & Biocenter Oulu, University of Oulu, Finland
| | - Petri Kursula
- Faculty of Biochemistry and Molecular Medicine & Biocenter Oulu, University of Oulu, Finland.,Department of Biomedicine, University of Bergen, Norway
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9
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Berg Klenow M, Iversen C, Wendelboe Lund F, Mularski A, Busk Heitmann AS, Dias C, Nylandsted J, Simonsen AC. Annexins A1 and A2 Accumulate and Are Immobilized at Cross-Linked Membrane-Membrane Interfaces. Biochemistry 2021; 60:1248-1259. [PMID: 33861586 DOI: 10.1021/acs.biochem.1c00126] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Rapid membrane repair is required to ensure cell survival after rupture of the plasma membrane. The annexin family of proteins is involved in plasma membrane repair (PMR) and is activated by the influx of Ca2+ from the extracellular medium at the site of injury. Annexins A1 and A2 (ANXA1 and ANXA2, respectively) are structurally similar and bind to negatively charged phosphatidylserine (PS) to induce membrane cross-linking and to promote fusion, which are both essential processes that occur during membrane repair. The degree of annexin accumulation and the annexin mobility at cross-linked membranes are important aspects of ANXA1 and ANXA2 function in repair. Here, we quantify ANXA1- and ANXA2-induced membrane cross-linking between giant unilamellar vesicles (GUVs). Time-lapse measurements show that ANXA1 and ANXA2 can induce membrane cross-linking on a time scale compatible with PMR. Cross-linked membrane-membrane interfaces between the GUVs persist in time without fusion, and quantification of confocal microscopy images demonstrates that ANXA1, ANXA2, and, to a lesser extent, PS lipids accumulate at the double membrane interface. Fluorescence recovery after photobleaching shows that the annexins are fully immobilized at the double membrane interface, whereas PS lipids display a 75% decrease in mobility. In addition, the complete immobilization of annexins between two membranes indicates a high degree of network formation between annexins, suggesting that membrane cross-linking is mainly driven by protein-protein interactions.
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Affiliation(s)
- Martin Berg Klenow
- Department of Physics, Chemistry and Pharmacy (FKF), University of Southern Denmark (SDU), Campusvej 55, 5230 Odense M, Denmark
| | - Christoffer Iversen
- Department of Physics, Chemistry and Pharmacy (FKF), University of Southern Denmark (SDU), Campusvej 55, 5230 Odense M, Denmark
| | - Frederik Wendelboe Lund
- Department of Physics, Chemistry and Pharmacy (FKF), University of Southern Denmark (SDU), Campusvej 55, 5230 Odense M, Denmark
| | - Anna Mularski
- Department of Physics, Chemistry and Pharmacy (FKF), University of Southern Denmark (SDU), Campusvej 55, 5230 Odense M, Denmark
| | - Anne Sofie Busk Heitmann
- Membrane Integrity, Danish Cancer Society Research Center, Strandboulevarden 49, 2100 Copenhagen Ø, Denmark
| | - Catarina Dias
- Membrane Integrity, Danish Cancer Society Research Center, Strandboulevarden 49, 2100 Copenhagen Ø, Denmark
| | - Jesper Nylandsted
- Membrane Integrity, Danish Cancer Society Research Center, Strandboulevarden 49, 2100 Copenhagen Ø, Denmark.,Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3C, DK-2200 Copenhagen N, Denmark
| | - Adam Cohen Simonsen
- Department of Physics, Chemistry and Pharmacy (FKF), University of Southern Denmark (SDU), Campusvej 55, 5230 Odense M, Denmark
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