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Galvagnion C, Barclay A, Makasewicz K, Marlet FR, Moulin M, Devos JM, Linse S, Martel A, Porcar L, Sparr E, Pedersen MC, Roosen-Runge F, Arleth L, Buell AK. Structural characterisation of α-synuclein-membrane interactions and the resulting aggregation using small angle scattering. Phys Chem Chem Phys 2024; 26:10998-11013. [PMID: 38526443 DOI: 10.1039/d3cp05928f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/26/2024]
Abstract
The presence of amyloid fibrils is a hallmark of several neurodegenerative diseases. Some amyloidogenic proteins, such as α-synuclein and amyloid β, interact with lipids, and this interaction can strongly favour the formation of amyloid fibrils. In particular the primary nucleation step, i.e. the de novo formation of amyloid fibrils, has been shown to be accelerated by lipids. However, the exact mechanism of this acceleration is still mostly unclear. Here we use a range of scattering methods, such as dynamic light scattering (DLS) and small angle X-ray and neutron scattering (SAXS and SANS) to obtain structural information on the binding of α-synuclein to model membranes formed from negatively charged lipids and their co-assembly into amyloid fibrils. We find that the model membranes take an active role in the reaction. The binding of α synuclein to the model membranes immediately induces a major structural change in the lipid assembly, which leads to a break-up into small and mostly disc- or rod-like lipid-protein particles. This transition can be reversed by temperature changes or proteolytic protein removal. Incubation of the small lipid-α-synuclein particles for several hours, however, leads to amyloid fibril formation, whereby the lipids are incorporated into the amyloid fibrils.
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Affiliation(s)
- Céline Galvagnion
- Department of Drug Design and Pharmacology, University of Copenhagen, 2100 Copenhagen, Denmark.
| | - Abigail Barclay
- Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Katarzyna Makasewicz
- Division of Physical Chemistry, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, SE-22100, Lund, Sweden
| | | | - Martine Moulin
- Institut Laue-Langevin, 71 avenue des Martyrs, 38042 Grenoble, France
| | - Juliette M Devos
- Institut Laue-Langevin, 71 avenue des Martyrs, 38042 Grenoble, France
| | - Sara Linse
- Department of Biochemistry and Structural Biology, Lund University, SE22100 Lund, Sweden
| | - Anne Martel
- Institut Laue-Langevin, 71 avenue des Martyrs, 38042 Grenoble, France
| | - Lionel Porcar
- Institut Laue-Langevin, 71 avenue des Martyrs, 38042 Grenoble, France
| | - Emma Sparr
- Division of Physical Chemistry, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, SE-22100, Lund, Sweden
| | | | - Felix Roosen-Runge
- Division of Physical Chemistry, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, SE-22100, Lund, Sweden
- Department of Biomedical Sciences and Biofilms Research Center for Biointerfaces, Malmö University, Malmö, Sweden
| | - Lise Arleth
- Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Alexander K Buell
- Department of Biotechnology and Biomedicine, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.
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2
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Larsen AH, Brookes E, Pedersen MC, Kirkensgaard JJK. Shape2SAS: a web application to simulate small-angle scattering data and pair distance distributions from user-defined shapes. J Appl Crystallogr 2023; 56:1287-1294. [PMID: 37555217 PMCID: PMC10405587 DOI: 10.1107/s1600576723005848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 07/03/2023] [Indexed: 08/10/2023] Open
Abstract
Shape2SAS is a web application that allows researchers and students to build intuition about and understanding of small-angle scattering. It is available at https://somo.chem.utk.edu/shape2sas. The user defines a model of arbitrary shape by combining geometrical subunits, and Shape2SAS then calculates and displays the scattering intensity and the pair distance distribution, as well as a visualization of the user-defined shape. Simulated data with realistic noise are also generated. Here, it is demonstrated how Shape2SAS can calculate and display the different scattering patterns for various geometrical shapes, such as spheres and cylinders. It is also shown how the effect of structure factors can be visualized. Finally, it is indicated how multi-contrast particles can readily be generated, and how the calculated scattering may be used to validate and visualize analytical models generated in analysis software for fitting small-angle scattering data.
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Affiliation(s)
| | | | | | - Jacob Judas Kain Kirkensgaard
- Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
- Department of Food Science, University of Copenhagen, Copenhagen, Denmark
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3
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Barclay A, Kragelund BB, Arleth L, Pedersen MC. Modeling of flexible membrane-bound biomolecular complexes for solution small-angle scattering. J Colloid Interface Sci 2023; 635:611-621. [PMID: 36634513 DOI: 10.1016/j.jcis.2022.12.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 11/18/2022] [Accepted: 12/06/2022] [Indexed: 12/14/2022]
Abstract
Recent advances in protein expression protocols, sample handling, and experimental set up of small-angle scattering experiments have allowed users of the technique to structurally investigate biomolecules of growing complexity and structural disorder. Notable examples include intrinsically disordered proteins, multi-domain proteins and membrane proteins in suitable carrier systems. Here, we outline a modeling scheme for calculating the scattering profiles from such complex samples. This kind of modeling is necessary for structural information to be refined from the corresponding data. The scheme bases itself on a hybrid of classical form factor based modeling and the well-known spherical harmonics-based formulation of small-angle scattering amplitudes. Our framework can account for flexible domains alongside other structurally elaborate components of the molecular system in question. We demonstrate the utility of this modeling scheme through a recent example of a structural model of the growth hormone receptor membrane protein in a phospholipid bilayer nanodisc which is refined against experimental SAXS data. Additionally we investigate how the scattering profiles from the complex would appear under different scattering contrasts. For each contrast situation we discuss what structural information is contained and the related consequences for modeling of the data.
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Affiliation(s)
- Abigail Barclay
- Condensed Matter Physics, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, Copenhagen 2100, Denmark.
| | - Birthe B Kragelund
- Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, Copenhagen 2200, Denmark.
| | - Lise Arleth
- Condensed Matter Physics, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, Copenhagen 2100, Denmark.
| | - Martin Cramer Pedersen
- Condensed Matter Physics, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, Copenhagen 2100, Denmark.
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4
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Pedersen MC, Hyde ST, Ramsden S, Kirkensgaard JJK. Mapping hyperbolic order in curved materials. Soft Matter 2023; 19:1586-1595. [PMID: 36749349 DOI: 10.1039/d2sm01403c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Nature employs an impressive range of topologically complex ordered nanostructures that occur in various forms in both natural and synthetic materials. A particular class of these exhibits negative curvature and forms periodic saddle-shaped surfaces in three dimensions. Unlike pattern formation on flat or positively curved surfaces like spherical systems, the understanding of patterning on such surfaces is highly complicated due to the structures being intrinsically intertwined in three dimensions. We present a new method for visualisation and analysis of patterns on triply periodic negatively curved surfaces by mapping to two-dimensional hyperbolic space analogous to spherical projections in cartography thus effectively creating a more accessible "hyperbolic map" of the pattern. Specifically, we exemplify the method via the simplest triply periodic minimal surfaces: the Primitive, Diamond, and Gyroid in their universal cover along with decorations from a soft materials, whose structures involve decorations of soft matter on negatively curved surfaces, not necessarily minimal.
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Affiliation(s)
| | | | - Stuart Ramsden
- National Computational Infrastructure (NCI) Vizlab, Australian National University, Australia
| | - Jacob J K Kirkensgaard
- Niels Bohr Institute, University of Copenhagen, Denmark.
- Department of Food Science, University of Copenhagen, Denmark
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5
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Johansen NT, Tidemand FG, Pedersen MC, Arleth L. Travel light: Essential packing for membrane proteins with an active lifestyle. Biochimie 2023; 205:3-26. [PMID: 35963461 DOI: 10.1016/j.biochi.2022.07.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 06/29/2022] [Accepted: 07/23/2022] [Indexed: 11/02/2022]
Abstract
We review the considerable progress during the recent decade in the endeavours of designing, optimising, and utilising carrier particle systems for structural and functional studies of membrane proteins in near-native environments. New and improved systems are constantly emerging, novel studies push the perceived limits of a given carrier system, and specific carrier systems consolidate and entrench themselves as the system of choice for particular classes of target membrane protein systems. This review covers the most frequently used carrier systems for such studies and emphasises similarities and differences between these systems as well as current trends and future directions for the field. Particular interest is devoted to the biophysical properties and membrane mimicking ability of each system and the manner in which this may impact an embedded membrane protein and an eventual structural or functional study.
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Affiliation(s)
- Nicolai Tidemand Johansen
- Section for Transport Biology, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, Frederiksberg C, 1871, Denmark.
| | - Frederik Grønbæk Tidemand
- Section for Transport Biology, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, Frederiksberg C, 1871, Denmark
| | - Martin Cramer Pedersen
- Condensed Matter Physics, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, Copenhagen E, 2100, Denmark
| | - Lise Arleth
- Condensed Matter Physics, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, Copenhagen E, 2100, Denmark
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6
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Larsen AH, Brookes E, Pedersen MC, Kirkensgaard JJK. Shape2SAS -- a web application to simulate small-angle scattering data and pair distance distributions from user-defined shapes. ArXiv 2023:arXiv:2301.04976v1. [PMID: 36713243 PMCID: PMC9882588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Shape2SAS is a web application that allows researchers and students to build intuition and understanding of small-angle scattering. It is available at https://somo.chem.utk.edu/shape2sas. The user defines a model of arbitrary shape by combining geometrical subunits, and Shape2SAS then calculates and displays the scattering intensity, the pair distance distribution as well as a visualization of the user-defined shape. Simulated data with realistic noise are also generated. We demonstrate how Shape2SAS can calculate and display the different scattering patterns for various geometrical shapes, such as spheres and cylinders. We also demonstrate how the effect of structure factors can be visualized. Finally, we show how multi-contrast particles can readily be generated, and how the calculated scattering may be used to validate and visualize analytical models generated in analysis software for fitting small-angle scattering data.
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Affiliation(s)
| | | | | | - Jacob Judas Kain Kirkensgaard
- University of Copenhagen, Niels Bohr Institute, Copenhagen, Denmark
- University of Copenhagen, Department of Food Science, Copenhagen, Denmark
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7
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Tidemand FG, Blemmer S, Johansen NT, Arleth L, Pedersen MC. Non-ionic detergent assists formation of supercharged nanodiscs and insertion of membrane proteins. Biochim Biophys Acta Biomembr 2022; 1864:183884. [PMID: 35182589 DOI: 10.1016/j.bbamem.2022.183884] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 01/18/2022] [Accepted: 02/01/2022] [Indexed: 12/12/2022]
Abstract
Nanodiscs are used to stabilize membrane proteins in a lipid environment and enable investigations of the function and structure of these. Membrane proteins are often only available in small amounts, and thus the stability and ease of use of the nanodiscs are essential. We have recently explored circularizing and supercharging membrane scaffolding proteins (MSPs) for nanodisc formation and found increased temporal stability at elevated temperatures. In the present study, we investigate six different supercharged MSPs and their ability to form nanodiscs: three covalently circularized and the three non-circularized, linear versions. Using standard reconstitution protocols using cholate as the reconstitution detergent, we found that two of the linear constructs formed multiple lipid-protein species, whereas adding n-Dodecyl-B-D-maltoside (DDM) with the cholate in the reconstitution gave rise to single-species nanodisc formation for these MSPs. For all MSPs, the formed nanodiscs were analyzed by small-angle X-ray scattering (SAXS), which showed similar structures for each MSP, respectively, suggesting that the structures of the formed nanodiscs are independent of the initial DDM content, as long as cholate is present. Lastly, we incorporated the membrane protein proteorhodopsin into the supercharged nanodiscs and observed a considerable increase in incorporation yield with the addition of DDM. For the three circularized MSPs, a single major species appeared in the size exclusion chromatography (SEC) chromatogram, suggesting monodisperse nanodiscs with proteorhodopsin incorporated, which is in strong contrast to the samples without DDM showing almost no incorporation and high polydispersity.
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Affiliation(s)
- Frederik G Tidemand
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Sara Blemmer
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Nicolai T Johansen
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark; Section for Transport Biology, Department of Plant and Environmental Sciences, University of Copenhagen, 1871 Frederiksberg C, Denmark
| | - Lise Arleth
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Martin Cramer Pedersen
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark.
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8
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Barclay A, Tidemand Johansen N, Tidemand FG, Arleth L, Pedersen MC. Global fitting of multiple data frames from SEC–SAXS to investigate the structure of next-generation nanodiscs. Acta Crystallogr D Struct Biol 2022; 78:483-493. [PMID: 35362471 PMCID: PMC8972807 DOI: 10.1107/s2059798322001838] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 02/16/2022] [Indexed: 11/10/2022]
Abstract
The combination of online size-exclusion chromatography and small-angle X-ray scattering (SEC–SAXS) is rapidly becoming a key technique for structural investigations of elaborate biophysical samples in solution. Here, a novel model-refinement strategy centred around the technique is outlined and its utility is demonstrated by analysing data series from several SEC–SAXS experiments on phospholipid bilayer nanodiscs. Using this method, a single model was globally refined against many frames from the same data series, thereby capturing the frame-to-frame tendencies of the irradiated sample. These are compared with models refined in the traditional manner, in which refinement is based on the average profile of a set of consecutive frames from the same data series without an in-depth comparison of individual frames. This is considered to be an attractive model-refinement scheme as it considerably lowers the total number of parameters refined from the data series, produces tendencies that are automatically consistent between frames, and utilizes a considerably larger portion of the recorded data than is often performed in such experiments. Additionally, a method is outlined for correcting a measured UV absorption signal by accounting for potential peak broadening by the experimental setup.
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9
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Johansen NT, Bonaccorsi M, Bengtsen T, Larsen AH, Tidemand FG, Pedersen MC, Huda P, Berndtsson J, Darwish T, Yepuri NR, Martel A, Pomorski TG, Bertarello A, Sansom MS, Rapp M, Crehuet R, Schubeis T, Lindorff-Larsen K, Pintacuda G, Arleth L. Mg 2+-dependent conformational equilibria in CorA and an integrated view on transport regulation. eLife 2022; 11:71887. [PMID: 35129435 PMCID: PMC8865849 DOI: 10.7554/elife.71887] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 02/04/2022] [Indexed: 11/13/2022] Open
Abstract
The CorA family of proteins regulates the homeostasis of divalent metal ions in many bacteria, archaea, and eukaryotic mitochondria, making it an important target in the investigation of the mechanisms of transport and its functional regulation. Although numerous structures of open and closed channels are now available for the CorA family, the mechanism of the transport regulation remains elusive. Here, we investigated the conformational distribution and associated dynamic behaviour of the pentameric Mg2+ channel CorA at room temperature using small-angle neutron scattering (SANS) in combination with molecular dynamics (MD) simulations and solid-state nuclear magnetic resonance spectroscopy (NMR). We find that neither the Mg2+-bound closed structure nor the Mg2+-free open forms are sufficient to explain the average conformation of CorA. Our data support the presence of conformational equilibria between multiple states, and we further find a variation in the behaviour of the backbone dynamics with and without Mg2+. We propose that CorA must be in a dynamic equilibrium between different non-conducting states, both symmetric and asymmetric, regardless of bound Mg2+ but that conducting states become more populated in Mg2+-free conditions. These properties are regulated by backbone dynamics and are key to understanding the functional regulation of CorA.
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Affiliation(s)
| | - Marta Bonaccorsi
- Centre de RMN à Très hauts Champs de Lyon, UMR 5280, CNRS, University of Lyon, Villeurbanne, France
| | - Tone Bengtsen
- Department of Biology, University of Copenhagen, Copenhagen N, Denmark
| | - Andreas Haahr Larsen
- Condensed Matter Physics, Niels Bohr Institute, University of Copenhagen, Copenhagen E, Denmark
| | | | - Martin Cramer Pedersen
- Condensed Matter Physics, Niels Bohr Institute, University of Copenhagen, Copenhagen E, Denmark
| | - Pie Huda
- Australian Institute for Bioengineering and Nanotechnology, University of Queensland, Brisbane, Australia
| | - Jens Berndtsson
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Tamim Darwish
- National Deuteration Facility, Australian Nuclear Science and Technology Organization, Lucas Heights, Australia
| | - Nageshewar Rao Yepuri
- National Deuteration Facility, Australian Nuclear Science and Technology Organization, Lucas Heights, Australia
| | | | - Thomas Günther Pomorski
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Andrea Bertarello
- Centre de RMN à Très hauts Champs de Lyon, UMR 5280, CNRS, University of Lyon, Villeurbanne, France
| | - Mark Sp Sansom
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Mikaela Rapp
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Ramon Crehuet
- Department of Biology, University of Copenhagen, Copenhagen N, Denmark
| | - Tobias Schubeis
- Centre de RMN à Très hauts Champs de Lyon, UMR 5280, CNRS, University of Lyon, Villeurbanne, France
| | | | - Guido Pintacuda
- Centre de RMN à Très hauts Champs de Lyon, UMR 5280, CNRS, University of Lyon, Villeurbanne, France
| | - Lise Arleth
- Condensed Matter Physics, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
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10
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Pedersen MC, Robins V, Hyde ST. The intrinsic group-subgroup structures of the Diamond and Gyroid minimal surfaces in their conventional unit cells. Acta Crystallogr A Found Adv 2022; 78:56-58. [PMID: 34967329 DOI: 10.1107/s2053273321012936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 12/06/2021] [Indexed: 11/10/2022] Open
Abstract
The intrinsic, hyperbolic crystallography of the Diamond and Gyroid minimal surfaces in their conventional unit cells is introduced and analysed. Tables are constructed of symmetry subgroups commensurate with the translational symmetries of the surfaces as well as group-subgroup lattice graphs.
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Affiliation(s)
| | - Vanessa Robins
- Research School of Physics, Australian National University, Australia
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11
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Larsen AH, Pedersen MC. Experimental noise in small-angle scattering can be assessed using the Bayesian indirect Fourier transformation. J Appl Crystallogr 2021. [DOI: 10.1107/s1600576721006877] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Small-angle X-ray and neutron scattering are widely used to investigate soft matter and biophysical systems. The experimental errors are essential when assessing how well a hypothesized model fits the data. Likewise, they are important when weights are assigned to multiple data sets used to refine the same model. Therefore, it is problematic when experimental errors are over- or underestimated. A method is presented, using Bayesian indirect Fourier transformation for small-angle scattering data, to assess whether or not a given small-angle scattering data set has over- or underestimated experimental errors. The method is effective on both simulated and experimental data, and can be used to assess and rescale the errors accordingly. Even if the estimated experimental errors are appropriate, it is ambiguous whether or not a model fits sufficiently well, as the `true' reduced χ2 of the data is not necessarily unity. This is particularly relevant for approaches where overfitting is an inherent challenge, such as reweighting of a simulated molecular dynamics trajectory against small-angle scattering data or ab initio modelling. Using the outlined method, it is shown that one can determine what reduced χ2 to aim for when fitting a model against small-angle scattering data. The method is easily accessible via the web interface BayesApp.
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12
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Pedersen MC, Kirkensgaard JJK, Hyde ST. Behind the curve: generating and analysing nets and tessellations on periodic minimal surfaces in their universal covering space. Acta Crystallogr A Found Adv 2021. [DOI: 10.1107/s0108767321094241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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13
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Johansen NT, Luchini A, Tidemand FG, Orioli S, Martel A, Porcar L, Arleth L, Pedersen MC. Structural and Biophysical Properties of Supercharged and Circularized Nanodiscs. Langmuir 2021; 37:6681-6690. [PMID: 34038130 DOI: 10.1021/acs.langmuir.1c00560] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Nanodiscs based on membrane scaffold proteins (MSPs) and phospholipids are used as membrane mimics to stabilize membrane proteins in solution for structural and functional studies. Combining small-angle X-ray scattering (SAXS), differential scanning calorimetry (DSC), and time-resolved small-angle neutron scattering (TR-SANS), we characterized the structure and lipid bilayer properties of five different nanodiscs made with dimyristoylphosphatidylcholine and different MSPs varying in size, charge, and circularization. Our SAXS modeling showed that the structural parameters of the embedded lipids are all similar, irrespective of the MSP properties. DSC showed that the lipid packing is not homogeneous in the nanodiscs and that a 20 Å wide boundary layer of lipids with perturbed packing is located close to the MSP, while the packing of central lipids is tighter than in large unilamellar vesicles. Finally, TR-SANS showed that lipid exchange rates in nanodiscs decrease with increasing nanodisc size and are lower for the nanodiscs made with supercharged MSPs compared to conventional nanodiscs. Altogether, the results provide a thorough biophysical understanding of the nanodisc as a model membrane system, which is important in order to carry out and interpret experiments on membrane proteins embedded in such systems.
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Affiliation(s)
- Nicolai Tidemand Johansen
- Structural Biophysics Group, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen E, Denmark
| | - Alessandra Luchini
- Structural Biophysics Group, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen E, Denmark
| | - Frederik Grønbæk Tidemand
- Structural Biophysics Group, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen E, Denmark
| | - Simone Orioli
- Structural Biophysics Group, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen E, Denmark
- Structural Biology and NMR Laboratory and Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Anne Martel
- Institut Laue Langevin, 38000 Grenoble, France
| | | | - Lise Arleth
- Structural Biophysics Group, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen E, Denmark
| | - Martin Cramer Pedersen
- Structural Biophysics Group, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen E, Denmark
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14
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Kassem N, Araya-Secchi R, Bugge K, Barclay A, Steinocher H, Khondker A, Wang Y, Lenard AJ, Bürck J, Sahin C, Ulrich AS, Landreh M, Pedersen MC, Rheinstädter MC, Pedersen PA, Lindorff-Larsen K, Arleth L, Kragelund BB. Order and disorder-An integrative structure of the full-length human growth hormone receptor. Sci Adv 2021; 7:7/27/eabh3805. [PMID: 34193419 PMCID: PMC8245047 DOI: 10.1126/sciadv.abh3805] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 05/18/2021] [Indexed: 05/13/2023]
Abstract
Because of its small size (70 kilodalton) and large content of structural disorder (>50%), the human growth hormone receptor (hGHR) falls between the cracks of conventional high-resolution structural biology methods. Here, we study the structure of the full-length hGHR in nanodiscs with small-angle x-ray scattering (SAXS) as the foundation. We develop an approach that combines SAXS, x-ray diffraction, and NMR spectroscopy data obtained on individual domains and integrate these through molecular dynamics simulations to interpret SAXS data on the full-length hGHR in nanodiscs. The hGHR domains reorient freely, resulting in a broad structural ensemble, emphasizing the need to take an ensemble view on signaling of relevance to disease states. The structure provides the first experimental model of any full-length cytokine receptor in a lipid membrane and exemplifies how integrating experimental data from several techniques computationally may access structures of membrane proteins with long, disordered regions, a widespread phenomenon in biology.
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Affiliation(s)
- Noah Kassem
- Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Ole Maaløes vej 5, 2200 Copenhagen N, Denmark
| | - Raul Araya-Secchi
- X-ray and Neutron Science, The Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - Katrine Bugge
- Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Ole Maaløes vej 5, 2200 Copenhagen N, Denmark
| | - Abigail Barclay
- X-ray and Neutron Science, The Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - Helena Steinocher
- Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Ole Maaløes vej 5, 2200 Copenhagen N, Denmark
| | - Adree Khondker
- Department of Physics and Astronomy, McMaster University, Hamilton, ON, Canada
| | - Yong Wang
- Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Ole Maaløes vej 5, 2200 Copenhagen N, Denmark
| | - Aneta J Lenard
- Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Ole Maaløes vej 5, 2200 Copenhagen N, Denmark
| | - Jochen Bürck
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology (KIT), POB 3640, 76021 Karlsruhe, Germany
| | - Cagla Sahin
- Department of Microbiology, Tumor, and Cell Biology, Karolinska Institutet, Stockholm 171 65, Sweden
| | - Anne S Ulrich
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology (KIT), POB 3640, 76021 Karlsruhe, Germany
| | - Michael Landreh
- Department of Microbiology, Tumor, and Cell Biology, Karolinska Institutet, Stockholm 171 65, Sweden
| | - Martin Cramer Pedersen
- X-ray and Neutron Science, The Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | | | - Per Amstrup Pedersen
- Department of Biology, University of Copenhagen, Universitetsparken 13, DK-2100 Copenhagen, Denmark
| | - Kresten Lindorff-Larsen
- Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Ole Maaløes vej 5, 2200 Copenhagen N, Denmark.
| | - Lise Arleth
- X-ray and Neutron Science, The Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.
| | - Birthe B Kragelund
- Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Ole Maaløes vej 5, 2200 Copenhagen N, Denmark.
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15
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Geisler R, Pedersen MC, Preisig N, Hannappel Y, Prévost S, Dattani R, Arleth L, Hellweg T. Aescin - a natural soap for the formation of lipid nanodiscs with tunable size. Soft Matter 2021; 17:1888-1900. [PMID: 33410858 DOI: 10.1039/d0sm02043e] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The saponin β-aescin from the seed extract of the horse chestnut tree Aesculus hippocastanum has demonstrated a beneficial role in clinical therapy which is in part related to its strong interaction with biological membranes. In this context the present work investigates the self-assembly of nm-sized discoidal lipid nanoparticles composed of β-aescin and the phospholipid 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). The discoidal lipid nanoparticles reassemble from small discs into larger discs, ribbons and finally stacks of sheets upon heating from gel-phase to fluid phase DMPC. The morphological transition of the lipid nano-particles is mainly triggered by the phospholipid phase state change. The final morphology depends on the phospholipid-to-saponin ratio and the actual temperature. The study is conducted by small-angle X-ray scattering (SAXS) and transmission (TEM) and freeze fracture electron microscopy (FFEM) are used to cover larger length scales. Two different models, representing a disc and ribbon-like shape are applied to the SAXS data, evaluating possible geometries and molecular mixing of the nano-particles. The stacked sheets are analysed by the Caillé theory.
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Affiliation(s)
- Ramsia Geisler
- Physical and Biophysical Chemistry, Bielefeld University, Universitätsstr. 25, 33615 Bielefeld, Germany.
| | - Martin Cramer Pedersen
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Natalie Preisig
- Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Yvonne Hannappel
- Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Sylvain Prévost
- ESRF-The European Synchrotron, 71, Avenue des Martyrs, 38000 Grenoble Cedex 9, France
| | - Rajeev Dattani
- ESRF-The European Synchrotron, 71, Avenue des Martyrs, 38000 Grenoble Cedex 9, France
| | - Lise Arleth
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Thomas Hellweg
- Physical and Biophysical Chemistry, Bielefeld University, Universitätsstr. 25, 33615 Bielefeld, Germany.
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16
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Abstract
We enumerate trivalent reticulations of two- and three-periodic hyperbolic surfaces by equal-sided
n
-gonal faces, (
n
, 3), where
n
= 7, 8, 9, 10, 12. These are the simplest hyperbolic generalizations of the planar graphene net, (6, 3) and dodecahedrane, (5, 3). The enumeration proceeds by deleting isometries of regular reticulations of two-dimensional hyperbolic space until the (
n
, 3) nets can be embedded in euclidean three-space via periodic hyperbolic surfaces. Those nets are then symmetrized in euclidean space retaining their net topology, leading to explicit crystallographic net embeddings whose edges are as equal as possible, affording candidtae patterns for graphitic schwarzites. The resulting schwarzites are the most symmetric examples. More than one hundred topologically distinct nets are described, most of which are novel.
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Affiliation(s)
- Stephen T. Hyde
- School of Chemistry, University of Sydney, New South Wales 2006, Australia
- Department of Applied Mathematics, Research School of Physics, Australian National University, ACT 2601, Australia
| | - Martin Cramer Pedersen
- Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
- Department of Applied Mathematics, Research School of Physics, Australian National University, ACT 2601, Australia
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17
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Cramer Pedersen M, Robins V, Mortensen K, Kirkensgaard JJK. Evolution of local motifs and topological proximity in self-assembled quasi-crystalline phases. Proc Math Phys Eng Sci 2020; 476:20200170. [PMID: 33071571 PMCID: PMC7544332 DOI: 10.1098/rspa.2020.0170] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 08/04/2020] [Indexed: 12/30/2023] Open
Abstract
Using methods from the field of topological data analysis, we investigate the self-assembly and emergence of three-dimensional quasi-crystalline structures in a single-component colloidal system. Combining molecular dynamics and persistent homology, we analyse the time evolution of persistence diagrams and particular local structural motifs. Our analysis reveals the formation and dissipation of specific particle constellations in these trajectories, and shows that the persistence diagrams are sensitive to nucleation and convergence to a final structure. Identification of local motifs allows quantification of the similarities between the final structures in a topological sense. This analysis reveals a continuous variation with density between crystalline clathrate, quasi-crystalline, and disordered phases quantified by 'topological proximity', a visualization of the Wasserstein distances between persistence diagrams. From a topological perspective, there is a subtle, but direct connection between quasi-crystalline, crystalline and disordered states. Our results demonstrate that topological data analysis provides detailed insights into molecular self-assembly.
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Affiliation(s)
| | - Vanessa Robins
- Department of Applied Mathematics, Australian National University, Canberra, Australia
| | - Kell Mortensen
- Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - Jacob J. K. Kirkensgaard
- Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
- Department of Food Science, University of Copenhagen, Copenhagen, Denmark
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18
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Geisler R, Pedersen MC, Hannappel Y, Schweins R, Prévost S, Dattani R, Arleth L, Hellweg T. Aescin-Induced Conversion of Gel-Phase Lipid Membranes into Bicelle-like Lipid Nanoparticles. Langmuir 2019; 35:16244-16255. [PMID: 31618036 DOI: 10.1021/acs.langmuir.9b02077] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Mixtures of the phospholipid 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and the saponin β-aescin spontaneously form monodisperse, bilayered discoidal micelles (also known as "bicelles" or "nanodisks") in aqueous solution. Such bicelles form below the melting temperature of DMPC when the phospholipids are in the rigid Lβ' state and are precursors of spontaneously formed vesicles. The aescin concentration must be far above the cmcaescin (≈0.3-0.4 mM). It was found that the shape and size of the bicelles are tunable by composition. High amounts of aescin decrease the size of the bicelles from diameters of ∼300 Å at 7 mol % to ∼120 Å at 30 mol % β-aescin. The structures are scrutinized by complementary small-angle X-ray and neutron scattering experiments. The scattering curves are subsequently analyzed by a model-independent (indirect Fourier transform analysis) and a model-based approach where bicelles are described as polydisperse bilayer disks encircled by a β-aescin rim. Moreover, the monomodal distribution and low polydispersity of the samples were confirmed by photon correlation spectroscopy. The discoidal structures were visualized by transmission electron microscopy.
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Affiliation(s)
| | - Martin Cramer Pedersen
- Niels Bohr Institute , University of Copenhagen , Universitetsparken 5 , 2100 Copenhagen , Denmark
| | | | - Ralf Schweins
- Institut Laue-Langevin , DS/LSS, 71 Avenue des Martyrs , 38042 Grenoble Cedex 9 , France
| | - Sylvain Prévost
- ESRF-The European Synchrotron , 71 Avenue des Martyrs , 38043 Grenoble Cedex 9 , France
| | - Rajeev Dattani
- ESRF-The European Synchrotron , 71 Avenue des Martyrs , 38043 Grenoble Cedex 9 , France
| | - Lise Arleth
- Niels Bohr Institute , University of Copenhagen , Universitetsparken 5 , 2100 Copenhagen , Denmark
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19
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Pedersen MC, Wang Y, Tidemand FG, Martel A, Lindorff-Larsen K, Arleth L. PSX, Protein–Solvent Exchange: software for calculation of deuterium-exchange effects in small-angle neutron scattering measurements from protein coordinates. J Appl Crystallogr 2019. [DOI: 10.1107/s1600576719012469] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Recent developments in neutron scattering instrumentation and sample handling have enabled studies of more complex biological samples and measurements at shorter exposure times. The experiments are typically conducted in D2O-based buffers to emphasize or diminish scattering from a particular component or to minimize background noise in the experiment. To extract most information from such experiments it is thus desirable to determine accurate estimates of how and when closely bound hydrogen atoms from the biomolecule exchange with the deuterium in the solvent. This article introduces and documents software, PSX, for exploring the effect of hydrogen–deuterium exchange for proteins solubilized in D2O as well as the underlying bioinformatical models. The software aims to be generally applicable for any atomistic structure of a protein and its surrounding environment, and thus captures effects of both heterogenous exchange rates throughout the protein structure and varying the experimental conditions such as pH and temperature. The paper concludes with examples of applications and estimates of the effect in typical scenarios emerging in small-angle neutron scattering on biological macromolecules in solution. The analysis presented here suggests that the common assumption of 90% exchange is in many cases an overestimate with the rapid sample handling systems currently available, which leads to fitting and calibration issues when analysing the data. Source code for the presented software is available from an online repository in which it is published under version 3 of the GNU publishing licence.
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20
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Johansen NT, Tidemand FG, Nguyen TTTN, Rand KD, Pedersen MC, Arleth L. Circularized and solubility‐enhanced
MSP
s facilitate simple and high‐yield production of stable nanodiscs for studies of membrane proteins in solution. FEBS J 2019; 286:1734-1751. [DOI: 10.1111/febs.14766] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 12/10/2018] [Accepted: 01/22/2019] [Indexed: 01/13/2023]
Affiliation(s)
| | | | - Tam T. T. N. Nguyen
- Protein Analysis Group Department of Pharmacy University of Copenhagen Denmark
| | - Kasper Dyrberg Rand
- Protein Analysis Group Department of Pharmacy University of Copenhagen Denmark
| | | | - Lise Arleth
- Structural Biophysics Niels Bohr Institute University of Copenhagen Denmark
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21
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Johansen NT, Pedersen MC, Porcar L, Martel A, Arleth L. Introducing SEC–SANS for studies of complex self-organized biological systems. Acta Crystallogr D Struct Biol 2018; 74:1178-1191. [DOI: 10.1107/s2059798318007180] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 05/14/2018] [Indexed: 01/11/2023]
Abstract
Small-angle neutron scattering (SANS) is maturing as a method for studying complex biological structures. Owing to the intrinsic ability of the technique to discern between 1H- and 2H-labelled particles, it is especially useful for contrast-variation studies of biological systems containing multiple components. SANS is complementary to small-angle X-ray scattering (SAXS), in which similar contrast variation is not easily performed but in which data with superior counting statistics are more easily obtained. Obtaining small-angle scattering (SAS) data on monodisperse complex biological structures is often challenging owing to sample degradation and/or aggregation. This problem is enhanced in the D2O-based buffers that are typically used in SANS. In SAXS, such problems are solved using an online size-exclusion chromatography (SEC) setup. In the present work, the feasibility of SEC–SANS was investigated using a series of complex and difficult samples of membrane proteins embedded in nanodisc particles that consist of both phospholipid and protein components. It is demonstrated that SEC–SANS provides data of sufficient signal-to-noise ratio for these systems, while at the same time circumventing aggregation. By combining SEC–SANS and SEC–SAXS data, an optimized basis for refining structural models of the investigated structures is obtained.
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22
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Pedersen MC, Delgado-Friedrichs O, Hyde ST. Surface embeddings of the Klein and the Möbius-Kantor graphs. Acta Crystallogr A Found Adv 2018; 74:223-232. [PMID: 29724968 DOI: 10.1107/s2053273318002036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 02/02/2018] [Indexed: 11/10/2022]
Abstract
This paper describes an invariant representation for finite graphs embedded on orientable tori of arbitrary genus, with working examples of embeddings of the Möbius-Kantor graph on the torus, the genus-2 bitorus and the genus-3 tritorus, as well as the two-dimensional, 7-valent Klein graph on the tritorus (and its dual: the 3-valent Klein graph). The genus-2 and -3 embeddings describe quotient graphs of 2- and 3-periodic reticulations of hyperbolic surfaces. This invariant is used to identify infinite nets related to the Möbius-Kantor and 7-valent Klein graphs.
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Affiliation(s)
- Martin Cramer Pedersen
- Department of Applied Mathematics, Research School of Physics and Engineering, Australian National University, Canberra ACT 2601, Australia
| | - Olaf Delgado-Friedrichs
- Department of Applied Mathematics, Research School of Physics and Engineering, Australian National University, Canberra ACT 2601, Australia
| | - Stephen T Hyde
- Department of Applied Mathematics, Research School of Physics and Engineering, Australian National University, Canberra ACT 2601, Australia
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23
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Midtgaard SR, Darwish TA, Pedersen MC, Huda P, Larsen AH, Jensen GV, Kynde SAR, Skar‐Gislinge N, Nielsen AJZ, Olesen C, Blaise M, Dorosz JJ, Thorsen TS, Venskutonytė R, Krintel C, Møller JV, Frielinghaus H, Gilbert EP, Martel A, Kastrup JS, Jensen PE, Nissen P, Arleth L. Invisible detergents for structure determination of membrane proteins by small‐angle neutron scattering. FEBS J 2017; 285:357-371. [DOI: 10.1111/febs.14345] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 10/20/2017] [Accepted: 11/21/2017] [Indexed: 12/23/2022]
Affiliation(s)
- Søren Roi Midtgaard
- Structural Biophysics X‐ray and Neutron Science The Niels Bohr Institute University of Copenhagen Denmark
| | - Tamim A. Darwish
- National Deuteration Facility Australian Nuclear Science and Technology Organization Lucas Heights Australia
| | - Martin Cramer Pedersen
- Structural Biophysics X‐ray and Neutron Science The Niels Bohr Institute University of Copenhagen Denmark
- Department of Applied Mathematics Research School of Physics and Engineering Australian National University Canberra Australia
| | - Pie Huda
- Structural Biophysics X‐ray and Neutron Science The Niels Bohr Institute University of Copenhagen Denmark
| | - Andreas Haahr Larsen
- Structural Biophysics X‐ray and Neutron Science The Niels Bohr Institute University of Copenhagen Denmark
| | - Grethe Vestergaard Jensen
- Structural Biophysics X‐ray and Neutron Science The Niels Bohr Institute University of Copenhagen Denmark
| | | | - Nicholas Skar‐Gislinge
- Structural Biophysics X‐ray and Neutron Science The Niels Bohr Institute University of Copenhagen Denmark
| | | | - Claus Olesen
- Department of Biomedicine Aarhus University Denmark
| | - Mickael Blaise
- Institut de Recherche en Infectiologie de Montpellier CNRS Université de Montpellier France
- Centre for Carbohydrate Recognition and Signaling Department of Molecular Biology Aarhus University Denmark
| | - Jerzy Józef Dorosz
- Department of Drug Design and Pharmacology Faculty of Health and Medical Sciences University of Copenhagen Denmark
| | - Thor Seneca Thorsen
- Department of Drug Design and Pharmacology Faculty of Health and Medical Sciences University of Copenhagen Denmark
| | - Raminta Venskutonytė
- Department of Drug Design and Pharmacology Faculty of Health and Medical Sciences University of Copenhagen Denmark
| | - Christian Krintel
- Department of Drug Design and Pharmacology Faculty of Health and Medical Sciences University of Copenhagen Denmark
| | - Jesper V. Møller
- Department of Biomedicine Aarhus University Denmark
- Department of Molecular Biology and Genetics Centre for Membrane Pumps in Cells and Disease – PUMPkin Danish National Research Foundation Aarhus University Denmark
| | | | - Elliot Paul Gilbert
- Australian Centre for Neutron Scattering Australian Nuclear Science and Technology Organization Lucas Heights Australia
| | | | - Jette Sandholm Kastrup
- Department of Drug Design and Pharmacology Faculty of Health and Medical Sciences University of Copenhagen Denmark
| | - Poul Erik Jensen
- Copenhagen Plant Science Center University of Copenhagen Denmark
| | - Poul Nissen
- Department of Molecular Biology and Genetics Centre for Membrane Pumps in Cells and Disease – PUMPkin Danish National Research Foundation Aarhus University Denmark
- DANDRITE Nordic‐EMBL Partnership for Molecular Medicine Aarhus University Denmark
| | - Lise Arleth
- Structural Biophysics X‐ray and Neutron Science The Niels Bohr Institute University of Copenhagen Denmark
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24
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Hyde ST, Cramer Pedersen M. Three-dimensional Euclidean crystallography and hyperbolic orbifolds. Acta Crystallogr A Found Adv 2017. [DOI: 10.1107/s2053273317094293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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25
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Pedersen MC, Hyde ST. Hyperbolic crystallography of two-periodic surfaces and associated structures. Acta Crystallogr A Found Adv 2017; 73:124-134. [PMID: 28248661 DOI: 10.1107/s2053273316019112] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 12/01/2016] [Indexed: 11/10/2022]
Abstract
This paper describes the families of the simplest, two-periodic constant mean curvature surfaces, the genus-two HCB and SQL surfaces, and their isometries. All the discrete groups that contain the translations of the genus-two surfaces embedded in Euclidean three-space modulo the translation lattice are derived and enumerated. Using this information, the subgroup lattice graphs are constructed, which contain all of the group-subgroup relations of the aforementioned quotient groups. The resulting groups represent the two-dimensional representations of subperiodic layer groups with square and hexagonal supergroups, allowing exhaustive enumeration of tilings and associated patterns on these surfaces. Two examples are given: a two-periodic [3,7]-tiling with hyperbolic orbifold symbol {\sf {2223}} and a {\sf {22222}} surface decoration.
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Affiliation(s)
- Martin Cramer Pedersen
- Department of Applied Mathematics, Research School of Physics and Engineering, Australian National University, Canberra ACT 2601, Australia
| | - Stephen T Hyde
- Department of Applied Mathematics, Research School of Physics and Engineering, Australian National University, Canberra ACT 2601, Australia
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26
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Abstract
Structural and functional aspects of high-density lipoproteins have been studied for over half a century. Due to the plasticity of this highly complex system, new aspects continue to be discovered. Here, we present a structural study of the human Apolipoprotein A1 (ApoA1) and investigate the role of its N-terminal domain, the so-called globular domain of ApoA1, in discoidal complexes with phospholipids and increasing amounts of cholesterol. Using a combination of solution-based small-angle x-ray scattering (SAXS) and molecular constrained data modeling, we show that the ApoA1-1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)-based particles are disk shaped with an elliptical cross section and composed by a central lipid bilayer surrounded by two stabilizing ApoA1 proteins. This structure is very similar to the particles formed in the so-called nanodisc system, which is based on N-terminal truncated ApoA1 protein. Although it is commonly agreed that the nanodisc is plain disk shaped, several more advanced structures have been proposed for the full-length ApoA1 in combination with POPC and cholesterol. This prompted us to make a detailed comparative study of the ApoA1 and nanodisc systems upon cholesterol uptake. Based on the presented SAXS analysis it is found that the N-terminal domains of ApoA1-POPC-cholesterol particles are not globular but instead an integrated part of the protein belt stabilizing the particles. Upon incorporation of increasing amounts of cholesterol, the presence of the N-terminal domain allows the bilayer thickness to increase while maintaining an overall flat bilayer structure. This is contrasted by the energetically more strained and less favorable lens shape required to fit the SAXS data from the N-terminal truncated nanodisc system upon cholesterol incorporation. This suggests that the N-terminal domain of ApoA1 actively participates in the stabilization of the ApoA1-POPC-cholesterol discoidal particle and allows for a more optimal lipid packing upon cholesterol uptake.
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Affiliation(s)
- Søren Roi Midtgaard
- X-Ray and Neutron Science, Niels Bohr Institute, University of Copenhagen, Denmark.
| | | | - Lise Arleth
- X-Ray and Neutron Science, Niels Bohr Institute, University of Copenhagen, Denmark
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27
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Abstract
Small-angle X-ray and neutron scattering have become increasingly popular owing to improvements in instrumentation and developments in data analysis, sample handling and sample preparation. For some time, it has been suggested that a more systematic approach to the quantification of the information content in small-angle scattering data would allow for a more optimal experiment planning and a more reliable data analysis. In the present article, it is shown how ray-tracing techniques in combination with a statistically rigorous data analysis provide an appropriate platform for such a systematic quantification of the information content in scattering data. As examples of applications, it is shown how the exposure time at different instrumental settings or contrast situations can be optimally prioritized in an experiment. Also, the gain in information by combining small-angle X-ray and neutron scattering is assessed. While solution small-angle scattering data of proteins and protein–lipid complexes are used as examples in the present case study, the approach is generalizable to a wide range of other samples and experimental techniques. The source code for the algorithms and ray-tracing components developed for this study has been made available on-line.
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28
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Midtgaard SR, Pedersen MC, Kirkensgaard JJK, Sørensen KK, Mortensen K, Jensen KJ, Arleth L. Self-assembling peptides form nanodiscs that stabilize membrane proteins. Soft Matter 2014; 10:738-752. [PMID: 24651399 DOI: 10.1039/c3sm51727f] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
New methods to handle membrane bound proteins, e.g. G-protein coupled receptors (GPCRs), are highly desirable. Recently, apoliprotein A1 (ApoA1) based lipoprotein particles have emerged as a new platform for studying membrane proteins, and it has been shown that they can self-assemble in combination with phospholipids to form discoidal shaped particles that can stabilize membrane proteins. In the present study, we have investigated an ApoA1 mimetic peptide with respect to its solution structure when in complex with phospholipids. This was achieved using a powerful combination of small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) supported by coarse-grained molecular dynamics simulations. The detailed structure of the discs was determined in unprecedented detail and it was found that they adopt a discoidal structure very similar to the ApoA1 based nanodiscs. We furthermore show that, like the ApoA1 and derived nanodiscs, these peptide discs can accommodate and stabilize a membrane protein. Finally, we exploit their dynamic properties and show that the 18A discs may be used for transferring membrane proteins and associated phospholipids directly and gently into phospholipid nanodiscs.
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29
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Kynde SAR, Skar-Gislinge N, Pedersen MC, Midtgaard SR, Simonsen JB, Schweins R, Mortensen K, Arleth L. Small-angle scattering gives direct structural information about a membrane protein inside a lipid environment. ACTA ACUST UNITED AC 2014; 70:371-83. [PMID: 24531471 DOI: 10.1107/s1399004713028344] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 10/15/2013] [Indexed: 12/11/2022]
Abstract
Monomeric bacteriorhodopsin (bR) reconstituted into POPC/POPG-containing nanodiscs was investigated by combined small-angle neutron and X-ray scattering. A novel hybrid approach to small-angle scattering data analysis was developed. In combination, these provided direct structural insight into membrane-protein localization in the nanodisc and into the protein-lipid interactions. It was found that bR is laterally decentred in the plane of the disc and is slightly tilted in the phospholipid bilayer. The thickness of the bilayer is reduced in response to the incorporation of bR. The observed tilt of bR is in good accordance with previously performed theoretical predictions and computer simulations based on the bR crystal structure. The result is a significant and essential step on the way to developing a general small-angle scattering-based method for determining the low-resolution structures of membrane proteins in physiologically relevant environments.
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Affiliation(s)
- Søren A R Kynde
- Structural Biophysics, Niels Bohr Institute, Faculty of Science, University of Copenhagen, Denmark
| | - Nicholas Skar-Gislinge
- Structural Biophysics, Niels Bohr Institute, Faculty of Science, University of Copenhagen, Denmark
| | - Martin Cramer Pedersen
- Structural Biophysics, Niels Bohr Institute, Faculty of Science, University of Copenhagen, Denmark
| | - Søren Roi Midtgaard
- Structural Biophysics, Niels Bohr Institute, Faculty of Science, University of Copenhagen, Denmark
| | - Jens Baek Simonsen
- Structural Biophysics, Niels Bohr Institute, Faculty of Science, University of Copenhagen, Denmark
| | | | - Kell Mortensen
- Structural Biophysics, Niels Bohr Institute, Faculty of Science, University of Copenhagen, Denmark
| | - Lise Arleth
- Structural Biophysics, Niels Bohr Institute, Faculty of Science, University of Copenhagen, Denmark
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30
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Abstract
A software framework for analysis of small-angle scattering data is presented. On the basis of molecular constraints and prior knowledge of the chemical composition of the sample, the software is capable of simultaneously fitting small-angle X-ray and neutron scattering data to analytical or semi-analytical models of biomacromolecules. The software features various fitting routines along with the possibility of incorporating instrumental resolution effects on the fit. Finally, trust region estimation, based on the profile likelihood strategy, is implemented. The algorithms and models are written in C, whereas the user interface is written in Python. Parallelization is implemented using the OpenMP extensions to C. The source code is available for free upon request orviathe associated code repository. The software runs on Linux, Windows and OSX and is available as an open-source initiative published under the General Publishing License.
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31
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Pedersen MC. You should have the privilege of dying once...and then return a year later. Dent Econ 1968; 58:27-30 passim. [PMID: 5242379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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