Lise Arleth

IT University of Copenhagen, København, Capital Region, Denmark

Are you Lise Arleth?

Claim your profile

Publications (65)213.99 Total impact

  • [Show abstract] [Hide abstract]
    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. Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.
    Biophysical Journal 07/2015; 109(2):308-18. DOI:10.1016/j.bpj.2015.06.032 · 3.97 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Water based inks would be a strong advantage for large scale production of organic photovoltaics. Formation of water dispersible nanoparticles produced by the Landfester method is a promising route to achieve such inks. We provide new insights into key ink properties for poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) nanoparticles such as internal structure and crystallinity of the dispersed nanoparticles and the previously unreported drastic changes that occur when the ink is cast into a film. We observe through Transmission Electron Microscopy (TEM) and small angle X-ray scattering (SAXS) that the nanoparticles in dispersion are spherical with nano domains of P3HT – partly crystalline. When wet processed and dried into films the nanoparticles lose their spherical shape and become flattened to oblate shapes with a large aspect ratio. Most particles are observed to have a diameter 13 times of the particle height. After casting to a film the crystal domains adopt a preferred orientation with the majority of the nano crystals (68%) with face-on orientation to the substrate. We propose that low substrate surface energy is responsible for particle deformation and texturing.
    07/2015; DOI:10.1039/C5TA04980F
  • [Show abstract] [Hide abstract]
    ABSTRACT: De novo design and chemical synthesis of proteins and of other artificial structures, which mimic them, is a central strategy for understanding protein folding and for accessing proteins with novel functions. We have previously described carbohydrates as templates for the assembly of artificial proteins, so called carboproteins. The hypothesis is that the template pre-organizes the secondary structure elements and directs the formation of a tertiary structure, thus achieving structural economy in the combination of peptide, linker, and template. We speculate that the structural information from the template could facilitate protein folding. Here we report the design and synthesis of 3-helix bundle carboproteins on deoxy-hexopyranosides. The carboproteins were analyzed by CD, AUC, SAXS, and NMR, which revealed the formation of the first compact, and folded monomeric carboprotein distinctly different to a molten globule. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    ChemBioChem 07/2015; DOI:10.1002/cbic.201500285 · 3.09 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: 64Cu radiolabelled nanodiscs based on the 11 α-helix MSP1E3D1 protein and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine lipids were, for the first time, followed in vivo by positron emission tomography for evaluating the biodistribution of nanodiscs. A cancer tumor bearing mouse model was used for the investigations, and it was found that the approximately 13 nm nanodiscs, due to their size, permeate deeply into cancer tissue. This makes them promising candidates for both drug delivery purposes and as advanced imaging agents. For the radiolabelling, a simple approach for 64Cu radiolabelling of proteins via a chelating agent, DOTA, was developed. The reaction was performed at sufficiently mild conditions to be compatible with labelling of the protein part of a lipid-protein particle while fully conserving the particle structure including the amphipathic protein fold.
    PLoS ONE 07/2015; 10(7):e0129310. DOI:10.1371/journal.pone.0129310 · 3.23 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: PICK1 is a neuronal scaffolding protein containing a PDZ domain and an auto-inhibited BAR domain. BAR domains are membrane-sculpting protein modules generating membrane curvature and promoting membrane fission. Previous data suggest that BAR domains are organized in lattice-like arrangements when stabilizing membranes but little is known about structural organization of BAR domains in solution. Through a small-angle X-ray scattering (SAXS) analysis, we determine the structure of dimeric and tetrameric complexes of PICK1 in solution. SAXS and biochemical data reveal a strong propensity of PICK1 to form higher-order structures, and SAXS analysis suggests an offset, parallel mode of BAR-BAR oligomerization. Furthermore, unlike accessory domains in other BAR domain proteins, the positioning of the PDZ domains is flexible, enabling PICK1 to perform long-range, dynamic scaffolding of membrane-associated proteins. Together with functional data, these structural findings are compatible with a model in which oligomerization governs auto-inhibition of BAR domain function. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Structure 06/2015; 23(7). DOI:10.1016/j.str.2015.04.020 · 5.62 Impact Factor
  • [Show abstract] [Hide abstract]
    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.
    Journal of Applied Crystallography 12/2014; 47(6). DOI:10.1107/S1600576714024017 · 3.72 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The high flux at European Spallation Source (ESS) will allow for performing experiments with relatively small beam-sizes while maintaining a high intensity of the incoming beam. The pulsed nature of the source makes the facility optimal for time-of-flight small-angle neutron scattering (ToF-SANS). We find that a relatively compact SANS instrument becomes the optimal choice in order to obtain the widest possible q -range in a single setting and the best possible exploitation of the neutrons in each pulse and hence obtaining the highest possible flux at the sample position. The instrument proposed in the present article is optimised for performing fast measurements of small scattering volumes, typically down to 2×2×2 mm3, while covering a broad q -range from about 0.005 1/Å to 0.5 1/Å in a single instrument setting. This q -range corresponds to that available at a typical good BioSAXS instrument and is relevant for a wide set of biomacromolecular samples. A central advantage of covering the whole q -range in a single setting is that each sample has to be loaded only once. This makes it convenient to use the fully automated high-throughput flow-through sample changers commonly applied at modern synchrotron BioSAXS-facilities. The central drawback of choosing a very compact instrument is that the resolution in terms of δλ/λδλ/λ obtained with the short wavelength neutrons becomes worse than what is usually the standard at state-of-the-art SANS instruments. Our McStas based simulations of the instrument performance for a set of characteristic biomacromolecular samples show that the resulting smearing effects still have relatively minor effects on the obtained data and can be compensated for in the data analysis. However, in cases where a better resolution is required in combination with the large simultaneous q-range characteristic of the instrument, we show that this can be obtained by inserting a set of choppers.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 11/2014; 764:133–141. DOI:10.1016/j.nima.2014.06.084 · 1.22 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Phosphatidylcholine (PC) is a major component of eukaryotic cell membranes and one of the most commonly used phospholipids for reconstitution of membrane proteins into carrier systems such as lipid vesicles, micelles and nanodiscs. Selectively deuterated versions of this lipid have many applications, especially in structural studies using techniques such as NMR, neutron reflectivity and small-angle neutron scattering. Here we present a comprehensive study of selective deuteration of phosphatidylcholine through biosynthesis in a genetically modified strain of Escherichia coli. By carefully tuning the deuteration level in E. coli growth media and varying the deuteration of supplemented carbon sources, we show that it is possible to achieve a controlled deuteration for three distinct parts of the PC lipid molecule, namely the (a) lipid head group, (b) glycerol backbone and (c) fatty acyl tail. This biosynthetic approach paves the way for the synthesis of specifically deuterated, physiologically relevant phospholipid species which remain difficult to obtain through standard chemical synthesis.
    Applied Microbiology and Biotechnology 10/2014; 99(1). DOI:10.1007/s00253-014-6082-z · 3.34 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The thermodynamics and structural properties of flexible and rigid nonionic water/oil/surfactant microemulsions have been investigated using a two level-cut Gaussian random field method based on the Helfrich formalism. Ternary stability diagrams and scattering spectra have been calculated for different surfactant rigidities and spontaneous curvatures. A more important contribution of the Gaussian elastic constants compared to the bending one is observed on the ternary stability diagrams. Furthermore, influence of the spontaneous curvature of the surfactant points out a displacement of the instability domains which corresponds to the difference between the spontaneous and effective curvatures. We enlighten that a continuous transition from a connected water in oil droplets to a frustrated locally lamellar (oil in water in oil droplets) microstructure is found to occur when increasing the temperature for an oil-rich microemulsion. This continuous transition translated in a shift in the scattering functions, points out that the phase inversion phenomenon occurs by a coalescence of the water droplets.
    The Journal of Chemical Physics 04/2014; 140(16):164711. DOI:10.1063/1.4873357 · 2.95 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Structural studies of membrane proteins remain a great experimental challenge. Functional reconstitution into artificial nanoscale bilayer disc carriers that mimic the native bilayer environment allows the handling of membrane proteins in solution. This enables the use of small-angle scattering techniques for fast and reliable structural analysis. The difficulty with this approach is that the carrier discs contribute to the measured scattering intensity in a highly nontrivial fashion, making subsequent data analysis challenging. Here, an elegant solution to circumvent the intrinsic complexity brought about by the presence of the carrier disc is presented. In combination with small-angle neutron scattering (SANS) and the D 2 O/H 2 O-based solvent contrast-variation method, it is demonstrated that it is possible to prepare specifically deuterated carriers that become invisible to neutrons in 100% D 2 O at the length scales relevant to SANS. These `stealth' carrier discs may be used as a general platform for low-resolution structural studies of membrane proteins using well established data-analysis tools originally developed for soluble proteins.
    Acta Crystallographica Section D Biological Crystallography 02/2014; 70(Pt 2):317-328. DOI:10.1107/S1399004713027466 · 2.67 Impact Factor
  • [Show abstract] [Hide abstract]
    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.
    Acta Crystallographica Section D Biological Crystallography 02/2014; 70(Pt 2):371-383. DOI:10.1107/S1399004713028344 · 2.67 Impact Factor
  • [Show abstract] [Hide abstract]
    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.
    Soft Matter 01/2014; 10(5):738-52. DOI:10.1039/c3sm51727f · 4.03 Impact Factor
  • [Show abstract] [Hide abstract]
    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 or via the 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.
    Journal of Applied Crystallography 12/2013; 46(6):1894-1898. DOI:10.1107/S0021889813026022 · 3.72 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In most temperate bacteriophages, regulation of the choice of lysogenic or lytic life cycle is controlled by a CI repressor protein. Inhibition of transcription is dependent on a helix-turn-helix motif, often located in the N-terminal domain (NTD), which binds to specific DNA sequences (operator sites). Here the crystal structure of the NTD of the CI repressor from phage TP901-1 has been determined at 1.6 Å resolution, and at 2.6 Å resolution in complex with a 9 bp double-stranded DNA fragment that constitutes a half-site of the OL operator. This N-terminal construct, comprising residues 2-74 of the CI repressor, is monomeric in solution as shown by nuclear magnetic resonance (NMR), small angle X-ray scattering, and gel filtration and is monomeric in the crystal structures. The binding interface between the NTD and the half-site in the crystal is very similar to the interface that can be mapped by NMR in solution with a full palindromic site. The interactions seen in the complexes (in the crystal and in solution) explain the observed affinity for the OR site that is lower than that for the OL site and the specificity for the recognized DNA sequence in comparison to that for other repressors. Compared with many well-studied phage repressor systems, the NTD from TP901-1 CI has a longer extended scaffolding helix that, interestingly, is strongly conserved in putative repressors of Gram-positive pathogens. On the basis of sequence comparisons, we suggest that these bacteria also possess repressor/antirepressor systems similar to that found in phage TP901-1.
    Biochemistry 09/2013; 52(39). DOI:10.1021/bi400439y · 3.02 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: α-Helical coiled coil structures, which are noncovalently associated heptad repeat peptide sequences, are ubiquitous in nature. Similar amphipathic repeat sequences have also been found in helix-containing proteins and have played a central role in de novo design of proteins. In addition, they are promising tools for the construction of nanomaterials. Small-angle X-ray scattering (SAXS) has emerged as a new biophysical technique for elucidation of protein topology. Here, we describe a systematic study of the self-assembly of a small ensemble of coiled coil sequences using SAXS and analytical ultracentrifugation (AUC), which was correlated with molecular dynamics simulations. Our results show that even minor sequence changes have an effect on the folding topology and the self-assembly and that these differences can be observed by a combination of AUC, SAXS, and circular dichroism spectroscopy. A small difference in these methods was observed, as SAXS for one peptide and revealed the presence of a population of longer aggregates, which was not observed by AUC. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd.
    Journal of Peptide Science 05/2013; 19(5). DOI:10.1002/psc.2497 · 1.55 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: COMPLETE AUTHOR LIST PLEASE ACCESS ESS, the European Spallation Source, will be a major user facility at which researchers from academia and industry will investigate scientific questions using neutron beams. Neutron methods provide insights about the molecular building blocks of matter not available by other means. They are used for both basic and applied research. ESS will be a slow neutron source of unparallelled power and scientific performance. It will deliver its first protons to a solid, rotating tungsten target in 2019, which will in turn generate neutrons for delivery to an initial suite of seven neutron scattering research instruments. ESS will reach its full design specifications in 2025, with a suite of 22 research instruments. The publication of the Technical Design Report in 2013 represents an important milestone for the ESS project, marking its readiness to move forward with construction activities. This executive overview provides a brief summary of the key insights and findings of the Technical Design Report.
    04/2013; , ISBN: 978-91-980173-2-8
  • [Show abstract] [Hide abstract]
    ABSTRACT: The swelling behaviour of water-oil microemulsions - considering a surfactant layer between oil and water - has been studied using a two level-cuts Gaussian random field approach based on the Helfrich formalism. Microstructures and scattering properties of microemulsions have been calculated for different amounts of oil (and water) for flexible and rigid microemulsions. When the stiffness, the spontaneous curvature of the interfacial film, and the surface to volume ratio of the immiscible fluids are varied, the microemulsion topology and morphology change in order to minimize the microemulsion free energy. Our simulations point out a change in the microemulsion morphology as a function of the surfactant film rigidity and the composition of oil, water and the surfactant. Locally lamellar structures are found for rigid microemulsions, whereas for more flexible ones, the connected-droplet and/or bicontinuous structures are preferred. Furthermore, we show that the microemulsion swelling versus the volume fraction gives a specific signature of the microemulsion microstructure. This allows for discriminating between different types of microemulsions: flexible, frustrated and unfrustrated (close to bi-liquid foams), and connected structures as molten hexagonal and cubic phases. The universal swelling behaviour is compared to different analytic expressions of Disordered Open Connected (DOC) models for the microemulsion swelling versus the volume fraction.
    Physical Chemistry Chemical Physics 04/2013; 15(19). DOI:10.1039/c3cp43981j · 4.49 Impact Factor
  • International Conference on Neutron Scattering - ICNS 2013; 01/2013
  • Source
    Acta Crystallographica Section A Foundations of Crystallography 08/2012; 68(a1):s171-s171. DOI:10.1107/S0108767312096699 · 2.31 Impact Factor
  • Acta Crystallographica Section A Foundations of Crystallography 08/2012; 68(a1):s159-s159. DOI:10.1107/S0108767312096948 · 2.31 Impact Factor

Publication Stats

866 Citations
213.99 Total Impact Points


  • 2008–2015
    • IT University of Copenhagen
      København, Capital Region, Denmark
  • 2010
    • University of California, San Francisco
      San Francisco, California, United States
  • 1997–2009
    • Roskilde University
      • Department of Science, Systems and Models (NSM)
      Roskilde, Zealand, Denmark
  • 2004–2005
    • Los Alamos National Laboratory
      • Los Alamos Neutron Science Center
      Лос-Аламос, California, United States