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Rangl M, Schmandt N, Perozo E, Scheuring S. Real time dynamics of Gating-Related conformational changes in CorA. eLife 2019; 8:47322. [PMID: 31774394 PMCID: PMC6927688 DOI: 10.7554/elife.47322] [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] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 11/26/2019] [Indexed: 01/01/2023] Open
Abstract
CorA, a divalent-selective channel in the metal ion transport superfamily, is the major Mg2+-influx pathway in prokaryotes. CorA structures in closed (Mg2+-bound), and open (Mg2+-free) states, together with functional data showed that Mg2+-influx inhibits further Mg2+-uptake completing a regulatory feedback loop. While the closed state structure is a symmetric pentamer, the open state displayed unexpected asymmetric architectures. Using high-speed atomic force microscopy (HS-AFM), we explored the Mg2+-dependent gating transition of single CorA channels: HS-AFM movies during Mg2+-depletion experiments revealed the channel’s transition from a stable Mg2+-bound state over a highly mobile and dynamic state with fluctuating subunits to asymmetric structures with varying degree of protrusion heights from the membrane. Our data shows that at Mg2+-concentration below Kd, CorA adopts a dynamic (putatively open) state of multiple conformations that imply structural rearrangements through hinge-bending in TM1. We discuss how these structural dynamics define the functional behavior of this ligand-dependent channel.
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Affiliation(s)
- Martina Rangl
- Department of Anesthesiology, Weill Cornell Medical College, New York, United States.,Department of Physiology and Biophysics, Weill Cornell Medical College, New York, United States
| | - Nicolaus Schmandt
- Department of Biochemistry and Molecular Biophysics, The University of Chicago, Chicago, United States
| | - Eduardo Perozo
- Department of Biochemistry and Molecular Biophysics, The University of Chicago, Chicago, United States
| | - Simon Scheuring
- Department of Anesthesiology, Weill Cornell Medical College, New York, United States.,Department of Physiology and Biophysics, Weill Cornell Medical College, New York, United States
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2
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Rangl M, Miyagi A, Kowal J, Stahlberg H, Nimigean CM, Scheuring S. Real-time visualization of conformational changes within single MloK1 cyclic nucleotide-modulated channels. Nat Commun 2016; 7:12789. [PMID: 27647260 PMCID: PMC5034309 DOI: 10.1038/ncomms12789] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 08/01/2016] [Indexed: 01/11/2023] Open
Abstract
Eukaryotic cyclic nucleotide-modulated (CNM) ion channels perform various physiological roles by opening in response to cyclic nucleotides binding to a specialized cyclic nucleotide-binding domain. Despite progress in structure-function analysis, the conformational rearrangements underlying the gating of these channels are still unknown. Here, we image ligand-induced conformational changes in single CNM channels from Mesorhizobium loti (MloK1) in real-time, using high-speed atomic force microscopy. In the presence of cAMP, most channels are in a stable conformation, but a few molecules dynamically switch back and forth (blink) between at least two conformations with different heights. Upon cAMP depletion, more channels start blinking, with blinking heights increasing over time, suggestive of slow, progressive loss of ligands from the tetramer. We propose that during gating, MloK1 transitions from a set of mobile conformations in the absence to a stable conformation in the presence of ligand and that these conformations are central for gating the pore.
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Affiliation(s)
- Martina Rangl
- INSERM U1006, Aix-Marseille Université, Parc Scientifique et Technologique de Luminy, 163 Avenue de Luminy, Marseille 13009, France
| | - Atsushi Miyagi
- INSERM U1006, Aix-Marseille Université, Parc Scientifique et Technologique de Luminy, 163 Avenue de Luminy, Marseille 13009, France
| | - Julia Kowal
- Center for Cellular Imaging and NanoAnalytics, Biozentrum, University of Basel, Mattenstrasse 26, Basel CH-4058, Switzerland
| | - Henning Stahlberg
- Center for Cellular Imaging and NanoAnalytics, Biozentrum, University of Basel, Mattenstrasse 26, Basel CH-4058, Switzerland
| | - Crina M Nimigean
- INSERM U1006, Aix-Marseille Université, Parc Scientifique et Technologique de Luminy, 163 Avenue de Luminy, Marseille 13009, France.,Departments of Anesthesiology, Physiology and Biophysics, and Biochemistry, Weill Cornell Medical College, 1300 York Avenue, New York, New York 10065, USA
| | - Simon Scheuring
- INSERM U1006, Aix-Marseille Université, Parc Scientifique et Technologique de Luminy, 163 Avenue de Luminy, Marseille 13009, France
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Miyagi A, Chipot C, Rangl M, Scheuring S. High-speed atomic force microscopy shows that annexin V stabilizes membranes on the second timescale. Nat Nanotechnol 2016; 11:783-90. [PMID: 27271964 DOI: 10.1038/nnano.2016.89] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 04/26/2016] [Indexed: 05/24/2023]
Abstract
Annexins are abundant cytoplasmic proteins that can bind to negatively charged phospholipids in a Ca(2+)-dependent manner, and are known to play a role in the storage of Ca(2+) and membrane healing. Little is known, however, about the dynamic processes of protein-Ca(2+)-membrane assembly and disassembly. Here we show that high-speed atomic force microscopy (HS-AFM) can be used to repeatedly induce and disrupt annexin assemblies and study their structure, dynamics and interactions. Our HS-AFM set-up is adapted for such biological applications through the integration of a pumping system for buffer exchange and a pulsed laser system for uncaging caged compounds. We find that biochemically identical annexins (annexin V) display different effective Ca(2+) and membrane affinities depending on the assembly location, providing a wide Ca(2+) buffering regime while maintaining membrane stabilization. We also show that annexin is membrane-recruited and forms stable supramolecular assemblies within ∼5 s in conditions that are comparable to a membrane lesion in a cell. Molecular dynamics simulations provide atomic detail of the role played by Ca(2+) in the reversible binding of annexin to the membrane surface.
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Affiliation(s)
- Atsushi Miyagi
- U1006 INSERM, Université Aix-Marseille, Parc Scientifique et Technologique de Luminy, 163 avenue de Luminy, 13009 Marseille, France
| | - Christophe Chipot
- Laboratoire International Associé Centre National de la Recherche Scientifique et University of Illinois at Urbana-Champaign, UMR 7565, Université de Lorraine, BP 70239, 54506 Vandœuvre-lès-Nancy cedex, France
- Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801, USA
| | - Martina Rangl
- U1006 INSERM, Université Aix-Marseille, Parc Scientifique et Technologique de Luminy, 163 avenue de Luminy, 13009 Marseille, France
| | - Simon Scheuring
- U1006 INSERM, Université Aix-Marseille, Parc Scientifique et Technologique de Luminy, 163 avenue de Luminy, 13009 Marseille, France
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Kowal J, Chami M, Baumgartner P, Arheit M, Chiu PL, Rangl M, Scheuring S, Schröder GF, Nimigean CM, Stahlberg H. Ligand-induced structural changes in the cyclic nucleotide-modulated potassium channel MloK1. Nat Commun 2015; 5:3106. [PMID: 24469021 PMCID: PMC4086158 DOI: 10.1038/ncomms4106] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Accepted: 12/13/2013] [Indexed: 12/25/2022] Open
Abstract
Cyclic nucleotide-modulated ion channels are important for signal transduction and pacemaking in eukaryotes. The molecular determinants of ligand gating in these channels are still unknown, mainly because of a lack of direct structural information. Here we report ligand-induced conformational changes in full-length MloK1, a cyclic nucleotide-modulated potassium channel from the bacterium Mesorhizobium loti, analysed by electron crystallography and atomic force microscopy. Upon cAMP binding, the cyclic nucleotide-binding domains move vertically towards the membrane, and directly contact the S1–S4 voltage sensor domains. This is accompanied by a significant shift and tilt of the voltage sensor domain helices. In both states, the inner pore-lining helices are in an ‘open’ conformation. We propose a mechanism in which ligand binding can favour pore opening via a direct interaction between the cyclic nucleotide-binding domains and voltage sensors. This offers a simple mechanistic hypothesis for the coupling between ligand gating and voltage sensing in eukaryotic HCN channels. The molecular determinants underlying ligand gating of cyclic nucleotide-modulated ion channels remain unclear. Kowal et al. determine the conformational changes underlying cAMP binding to the bacterial channel MloK1, and propose a mechanism for coupling of ligand gating and voltage sensing in eukaryotic HCN channels.
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Affiliation(s)
- Julia Kowal
- Center for Cellular Imaging and NanoAnalytics, Biozentrum, University of Basel, Mattenstrasse 26, CH-4058 Basel, Switzerland
| | - Mohamed Chami
- Center for Cellular Imaging and NanoAnalytics, Biozentrum, University of Basel, Mattenstrasse 26, CH-4058 Basel, Switzerland
| | - Paul Baumgartner
- Center for Cellular Imaging and NanoAnalytics, Biozentrum, University of Basel, Mattenstrasse 26, CH-4058 Basel, Switzerland
| | - Marcel Arheit
- Center for Cellular Imaging and NanoAnalytics, Biozentrum, University of Basel, Mattenstrasse 26, CH-4058 Basel, Switzerland
| | | | - Martina Rangl
- U1006 INSERM, Aix-Marseille Université, Parc Scientifique et Technologique de Luminy, 163 Avenue de Luminy, 13009 Marseille, France
| | - Simon Scheuring
- U1006 INSERM, Aix-Marseille Université, Parc Scientifique et Technologique de Luminy, 163 Avenue de Luminy, 13009 Marseille, France
| | - Gunnar F Schröder
- 1] Forschungszentrum Jülich, Institute of Complex Systems, ICS-6: Structural Biochemistry, 52425 Jülich, Germany [2] Department of Physics, Heinrich-Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Crina M Nimigean
- Departments of Anesthesiology, Physiology and Biophysics, and Biochemistry, Weill Cornell Medical College, 1300 York Ave, New York, New York 10065, USA
| | - Henning Stahlberg
- Center for Cellular Imaging and NanoAnalytics, Biozentrum, University of Basel, Mattenstrasse 26, CH-4058 Basel, Switzerland
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Rangl M, Leitner M, Riihimäki T, Lehtonen S, Hytönen VP, Gruber HJ, Kulomaa M, Hinterdorfer P, Ebner A. Investigating the binding behaviour of two avidin-based testosterone binders using molecular recognition force spectroscopy. J Mol Recognit 2014; 27:92-7. [DOI: 10.1002/jmr.2337] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 10/18/2013] [Accepted: 10/22/2013] [Indexed: 01/18/2023]
Affiliation(s)
- Martina Rangl
- Institute of Biophysics; Johannes Kepler University Linz; Gruberstrasse 40 4020 Linz Austria
| | - Michael Leitner
- Institute of Biophysics; Johannes Kepler University Linz; Gruberstrasse 40 4020 Linz Austria
| | - Tiina Riihimäki
- Institute of Biomedical Technology; University of Tampere and Tampere University Hospital; Biokatu 6 33520 Tampere Finland
| | - Soili Lehtonen
- Institute of Biomedical Technology; University of Tampere and Tampere University Hospital; Biokatu 6 33520 Tampere Finland
| | - Vesa P. Hytönen
- Institute of Biomedical Technology; University of Tampere and Tampere University Hospital; Biokatu 6 33520 Tampere Finland
- Fimlab Laboratories; Biokatu 4 33520 Tampere Finland
| | - Hermann J. Gruber
- Institute of Biophysics; Johannes Kepler University Linz; Gruberstrasse 40 4020 Linz Austria
| | - Markku Kulomaa
- Institute of Biomedical Technology; University of Tampere and Tampere University Hospital; Biokatu 6 33520 Tampere Finland
| | - Peter Hinterdorfer
- Institute of Biophysics; Johannes Kepler University Linz; Gruberstrasse 40 4020 Linz Austria
- Center for Advanced Bioanalysis; Gruberstrasse 40 4020 Linz Austria
| | - Andreas Ebner
- Institute of Biophysics; Johannes Kepler University Linz; Gruberstrasse 40 4020 Linz Austria
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Rangl M, Ebner A, Yamada J, Rankl C, Tampé R, Gruber HJ, Rexach M, Hinterdorfer P. Single-Molecule Analysis of the Recognition Forces Underlying Nucleo-Cytoplasmic Transport. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201305359] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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7
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Rangl M, Ebner A, Yamada J, Rankl C, Tampé R, Gruber HJ, Rexach M, Hinterdorfer P. Single-molecule analysis of the recognition forces underlying nucleo-cytoplasmic transport. Angew Chem Int Ed Engl 2013; 52:10356-9. [PMID: 24038953 DOI: 10.1002/anie.201305359] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Indexed: 01/13/2023]
Affiliation(s)
- Martina Rangl
- Institute for Biophysics, Johannes Kepler University Linz, Gruberstr. 40, 4020 Linz (Austria)
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Leitner M, Fantner GE, Fantner EJ, Ivanova K, Ivanov T, Rangelow I, Ebner A, Rangl M, Tang J, Hinterdorfer P. Increased imaging speed and force sensitivity for bio-applications with small cantilevers using a conventional AFM setup. Micron 2012; 43:1399-407. [PMID: 22721963 PMCID: PMC3430863 DOI: 10.1016/j.micron.2012.05.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Revised: 05/15/2012] [Accepted: 05/15/2012] [Indexed: 11/27/2022]
Abstract
In this study, we demonstrate the increased performance in speed and sensitivity achieved by the use of small AFM cantilevers on a standard AFM system. For this, small rectangular silicon oxynitride cantilevers were utilized to arrive at faster atomic force microscopy (AFM) imaging times and more sensitive molecular recognition force spectroscopy (MRFS) experiments. The cantilevers we used had lengths between 13 and 46 μm, a width of about 11 μm, and a thickness between 150 and 600 nm. They were coated with chromium and gold on the backside for a better laser reflection. We characterized these small cantilevers through their frequency spectrum and with electron microscopy. Due to their small size and high resonance frequency we were able to increase the imaging speed by a factor of 10 without any loss in resolution for images from several μm scansize down to the nanometer scale. This was shown on bacterial surface layers (s-layer) with tapping mode under aqueous, near physiological conditions and on nuclear membranes in contact mode in ambient environment. In addition, we showed that single molecular forces can be measured with an up to 5 times higher force sensitivity in comparison to conventional cantilevers with similar spring constants.
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Affiliation(s)
- Michael Leitner
- Institute of Biophysics, Johannes Kepler University, A-4020 Linz, Austria
| | - Georg E. Fantner
- École Polytechnique Fédéral de Lausanne, Laboratoire de bio- et nano-instrumentation, CH-1015 Lausanne, Switzerland
| | - Ernest J. Fantner
- SCL-Sensortech, Tech Gate Vienna, Science and Technology Park, A-1220 Wien, Austria
| | - Katerina Ivanova
- SCL-Sensortech, Tech Gate Vienna, Science and Technology Park, A-1220 Wien, Austria
| | - Tzvetan Ivanov
- Fachgebiet für Mikro- und nanoelektronische Systeme, Fakultät für Elektrotechnik und Informationstechnik, TU Ilmenau, D-98693 Ilmenau, Germany
| | - Ivo Rangelow
- Fachgebiet für Mikro- und nanoelektronische Systeme, Fakultät für Elektrotechnik und Informationstechnik, TU Ilmenau, D-98693 Ilmenau, Germany
| | - Andreas Ebner
- Institute of Biophysics, Johannes Kepler University, A-4020 Linz, Austria
| | - Martina Rangl
- Institute of Biophysics, Johannes Kepler University, A-4020 Linz, Austria
| | - Jilin Tang
- Chinese Academy of Science, Chang Chun Institute of Applied Chemistry, 130021 Changchun, China
| | - Peter Hinterdorfer
- Institute of Biophysics, Johannes Kepler University, A-4020 Linz, Austria
- Center for Advanced Bioanalysis (CBL), A-4020 Linz, Austria
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9
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Rangl M, Ebner A, Yamada J, Rexach M, Hinterdorfer P. Single-Molecule Analysis of the Recognition Forces Underlying Nucleo-Cytoplasmic Transport. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.087] [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: 10/14/2022] Open
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10
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Riihimäki TA, Hiltunen S, Rangl M, Nordlund HR, Määttä JAE, Ebner A, Hinterdorfer P, Kulomaa MS, Takkinen K, Hytönen VP. Modification of the loops in the ligand-binding site turns avidin into a steroid-binding protein. BMC Biotechnol 2011; 11:64. [PMID: 21658230 PMCID: PMC3201017 DOI: 10.1186/1472-6750-11-64] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Accepted: 06/09/2011] [Indexed: 01/20/2023] Open
Abstract
Background Engineered proteins, with non-immunoglobulin scaffolds, have become an important alternative to antibodies in many biotechnical and therapeutic applications. When compared to antibodies, tailored proteins may provide advantageous properties such as a smaller size or a more stable structure. Results Avidin is a widely used protein in biomedicine and biotechnology. To tailor the binding properties of avidin, we have designed a sequence-randomized avidin library with mutagenesis focused at the loop area of the binding site. Selection from the generated library led to the isolation of a steroid-binding avidin mutant (sbAvd-1) showing micromolar affinity towards testosterone (Kd ~ 9 μM). Furthermore, a gene library based on the sbAvd-1 gene was created by randomizing the loop area between β-strands 3 and 4. Phage display selection from this library led to the isolation of a steroid-binding protein with significantly decreased biotin binding affinity compared to sbAvd-1. Importantly, differential scanning calorimetry and analytical gel-filtration revealed that the high stability and the tetrameric structure were preserved in these engineered avidins. Conclusions The high stability and structural properties of avidin make it an attractive molecule for the engineering of novel receptors. This methodology may allow the use of avidin as a universal scaffold in the development of novel receptors for small molecules.
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Affiliation(s)
- Tiina A Riihimäki
- Institute of Biomedical Technology, University of Tampere and Tampere University Hospital, FI-33520 Tampere, Finland
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Oliveira H, Rangl M, Ebner A, Mayer B, Hinterdorfer P, Pêgo AP. Molecular recognition force spectroscopy: a new tool to tailor targeted nanoparticles. Small 2011; 7:1236-1241. [PMID: 21456083 DOI: 10.1002/smll.201002074] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Indexed: 05/30/2023]
Abstract
The density of targeting moieties in a nanoparticle-based gene-delivery system has been shown to play a fundamental role in its vectoring performance. Here, molecular recognition force spectroscopy is proposed as a novel screening tool to optimize the density of targeting moieties of functionalized nanoparticles towards attaining cell-specific interaction. By tailoring the nanoparticle formulation, the unbinding event probability between nanoparticles tethered to an atomic force microscopy tip and neuronal cells is directly correlated to the nanoparticle gene-vectoring capacity. Additionally, new insights into protein-receptor interaction are revealed. This novel approach opens new avenues in the field of nanomedicine.
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Affiliation(s)
- Hugo Oliveira
- INEB-Instituto de Engenharia Biomédica, Divisão de Biomateriais, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal
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12
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Lamprecht C, Liashkovich I, Neves V, Danzberger J, Heister E, Rangl M, Coley HM, McFadden J, Flahaut E, Gruber HJ, Hinterdorfer P, Kienberger F, Ebner A. AFM imaging of functionalized carbon nanotubes on biological membranes. Nanotechnology 2009; 20:434001. [PMID: 19801758 DOI: 10.1088/0957-4484/20/43/434001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Multifunctional carbon nanotubes are promising for biomedical applications as their nano-size, together with their physical stability, gives access into the cell and various cellular compartments including the nucleus. However, the direct and label-free detection of carbon nanotube uptake into cells is a challenging task. The atomic force microscope (AFM) is capable of resolving details of cellular surfaces at the nanometer scale and thus allows following of the docking of carbon nanotubes to biological membranes. Here we present topographical AFM images of non-covalently functionalized single walled (SWNT) and double walled carbon nanotubes (DWNT) immobilized on different biological membranes, such as plasma membranes and nuclear envelopes, as well as on a monolayer of avidin molecules. We were able to visualize DWNT on the nuclear membrane while at the same time resolving individual nuclear pore complexes. Furthermore, we succeeded in localizing individual SWNT at the border of incubated cells and in identifying bundles of DWNT on cell surfaces by AFM imaging.
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Affiliation(s)
- C Lamprecht
- Institute of Biophysics, J Kepler University, Linz, Austria
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Rangl M, Nevo R, Liashkovich I, Shahin V, Reich Z, Ebner A, Hinterdorfer P. Inside Cover: Stable, Non-Destructive Immobilization of Native Nuclear Membranes to Micro-Structured PDMS for Single-Molecule Force Spectroscopy (ChemPhysChem 9-10/2009). Chemphyschem 2009. [DOI: 10.1002/cphc.200990035] [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: 11/09/2022]
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14
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Rangl M, Nevo R, Liashkovich I, Shahin V, Reich Z, Ebner A, Hinterdorfer P. Stable, non-destructive immobilization of native nuclear membranes to micro-structured PDMS for single-molecule force spectroscopy. Chemphyschem 2009; 10:1553-8. [PMID: 19507204 PMCID: PMC3013320 DOI: 10.1002/cphc.200900219] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2009] [Indexed: 11/08/2022]
Abstract
In eukaryotic cells the nucleus is separated from the cytoplasm by a double-membraned nuclear envelope (NE). Exchange of molecules between the two compartments is mediated by nuclear pore complexes (NPCs) that are embedded in the NE membranes. The translocation of molecules such as proteins and RNAs through the nuclear membrane is executed by transport shuttling factors (karyopherines). They thereby dock to particular binding sites located all over the NPC, the so-called phenylalanine-glycin nucleoporines (FG Nups). Molecular recognition force spectroscopy (MRFS) allows investigations of the binding at the single-molecule level. Therefore the AFM tip carries a ligand for example, a particular karyopherin whereas the nuclear membrane with its receptors is mounted on a surface. Hence, one of the first requirements to study the nucleocytoplasmatic transport mechanism using MRFS is the development of an optimized membrane preparation that preserves structure and function of the NPCs. In this study we present a stable non-destructive preparation method of Xenopus laevis nuclear envelopes. We use micro-structured polydimethylsiloxane (PDMS) that provides an ideal platform for immobilization and biological integrity due to its elastic, chemical and mechanical properties. It is a solid basis for studying molecular recognition, transport interactions, and translocation processes through the NPC. As a first recognition system we investigate the interaction between an important transport shuttling factor, importin beta, and its binding sites on the NPC, the FG-domains.
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Affiliation(s)
- Martina Rangl
- Institute for Biophysics, Johannes Kepler University of Linz, Altenbergerstr. 69, 4040 Linz (Austria)
| | - Reinat Nevo
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100 (Israel)
| | - Ivan Liashkovich
- Department of Physiology, University of Münster, Robert-Koch-str. 27b, 48149 Münster (Germany)
| | - Victor Shahin
- Department of Physiology, University of Münster, Robert-Koch-str. 27b, 48149 Münster (Germany)
| | - Ziv Reich
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100 (Israel)
| | - Andreas Ebner
- Institute for Biophysics, Johannes Kepler University of Linz, Altenbergerstr. 69, 4040 Linz (Austria)
| | - Peter Hinterdorfer
- Institute for Biophysics, Johannes Kepler University of Linz, Altenbergerstr. 69, 4040 Linz (Austria)
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