1
|
Bayer J, Becker J, Liu X, Gritsch L, Daiber E, Korn N, Oesterhelt F, Fraunholz M, Weber A, Wolz C. Differential survival of Staphylococcal species in macrophages. Mol Microbiol 2024; 121:470-480. [PMID: 37898563 DOI: 10.1111/mmi.15184] [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] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 09/05/2023] [Accepted: 10/02/2023] [Indexed: 10/30/2023]
Abstract
Staphylococcus aureus is considered an extracellular pathogen, yet the bacterium is able to survive within and escape from host cells. An agr/sae mutant of strain USA300 is unable to escape from macrophages but can replicate and survive within. We questioned whether such "non-toxic" S. aureus resembles the less pathogenic coagulase-negative Staphylococcal (CoNS) species like S. epidermidis, S. carnosus, S. lugdunensis, S. capitis, S. warneri, or S. pettenkoferi. We show that the CoNS are more efficiently killed in macrophage-like THP-1 cells or in human primary macrophages. Mutations in katA, copL, the regulatory system graRS, or sigB did not impact bacterial survival in THP-1 cells. Deletion of the superoxide dismutases impaired S. aureus survival in primary macrophages but not in THP-1 cells. However, expression of the S. aureus-specific sodM in S. epidermidis was not sufficient to protect this species from being killed. Thus, at least in those cells, better bacterial survival of S. aureus could not be linked to higher protection from ROS. However, "non-toxic" S. aureus was found to be insensitive to pH, whereas most CoNS were protected when phagosomal acidification was inhibited. Thus, species differences are at least partially linked to differences in sensitivity to acidification.
Collapse
Affiliation(s)
- Janina Bayer
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
- Cluster of Excellence EXC 2124 "Controlling Microbes to Fight Infections", University of Tübingen, Tübingen, Germany
| | - Janna Becker
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
- Cluster of Excellence EXC 2124 "Controlling Microbes to Fight Infections", University of Tübingen, Tübingen, Germany
| | - Xiao Liu
- Cluster of Excellence EXC 2124 "Controlling Microbes to Fight Infections", University of Tübingen, Tübingen, Germany
- Institute of Immunology, Department of Innate Immunity, University of Tübingen, Tübingen, Germany
| | - Lisa Gritsch
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
- Cluster of Excellence EXC 2124 "Controlling Microbes to Fight Infections", University of Tübingen, Tübingen, Germany
| | - Ellen Daiber
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
- Cluster of Excellence EXC 2124 "Controlling Microbes to Fight Infections", University of Tübingen, Tübingen, Germany
| | - Natalya Korn
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
- Cluster of Excellence EXC 2124 "Controlling Microbes to Fight Infections", University of Tübingen, Tübingen, Germany
| | - Filipp Oesterhelt
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
- Cluster of Excellence EXC 2124 "Controlling Microbes to Fight Infections", University of Tübingen, Tübingen, Germany
| | - Martin Fraunholz
- Department of Microbiology, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Alexander Weber
- Cluster of Excellence EXC 2124 "Controlling Microbes to Fight Infections", University of Tübingen, Tübingen, Germany
- Institute of Immunology, Department of Innate Immunity, University of Tübingen, Tübingen, Germany
| | - Christiane Wolz
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
- Cluster of Excellence EXC 2124 "Controlling Microbes to Fight Infections", University of Tübingen, Tübingen, Germany
| |
Collapse
|
2
|
Zhang L, Esquembre LA, Xia SN, Oesterhelt F, Hughes CC, Brötz-Oesterhelt H, Teufel R. Correction to "The Antibacterial Synnepyrroles from Human-associated Nocardiopsis sp. Show Protonophore Activity and Disrupt the Bacterial Cytoplasmic Membrane". ACS Chem Biol 2023; 18:1905. [PMID: 37440371 DOI: 10.1021/acschembio.3c00388] [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: 07/15/2023]
|
3
|
Zhang L, Esquembre LA, Xia SN, Oesterhelt F, Hughes CC, Brötz-Oesterhelt H, Teufel R. Antibacterial Synnepyrroles from Human-Associated Nocardiopsis sp. Show Protonophore Activity and Disrupt the Bacterial Cytoplasmic Membrane. ACS Chem Biol 2022; 17:2836-2848. [PMID: 36179367 DOI: 10.1021/acschembio.2c00460] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Actinobacteria have traditionally been an important source of bioactive natural products, although many genera remain poorly explored. Here, we report a group of distinctive pyrrole-containing natural products, named synnepyrroles, from Nocardiopsis synnemataformans. Detailed structural characterization by mass spectrometry and nuclear magnetic resonance (NMR) spectroscopy combined with isotope-labeling experiments revealed their molecular structures and biosynthetic precursors acetate, propionate, aspartate, and (for branched analogues) valine. The biosynthetic data points toward an unusual pathway for pyrrole formation via condensation of aspartate with diverse fatty acids that give rise to a unique pyrrole-3,4-dicarboxylate core and variable linear or terminally branched alkyl side chains. In addition, the bioactivity and mode of action of synnepyrrole A were characterized in Bacillus subtilis. Orienting assessment of the phenotype of synnepyrrole A-treated bacteria by high-resolution microscopy suggested the cytoplasmic membrane as the target structure. Further characterization of the membrane effects demonstrated dissipation of the membrane potential and intracellular acidification indicative of protonophore activity. At slightly higher concentrations, synnepyrrole A compromised the barrier function of the cytoplasmic membrane, allowing the passage of otherwise membrane-impermeable dye molecules.
Collapse
Affiliation(s)
- Lei Zhang
- Faculty of Biology, University of Freiburg, Schänzlestrasse 1, 79104 Freiburg, Germany
| | - Lidia Alejo Esquembre
- Department of Microbial Bioactive Compounds, Interfaculty Institute for Microbiology and Infection Medicine, University of Tübingen, 72076 Tübingen, Germany
| | - Shu-Ning Xia
- Department of Microbial Bioactive Compounds, Interfaculty Institute for Microbiology and Infection Medicine, University of Tübingen, 72076 Tübingen, Germany
| | - Filipp Oesterhelt
- Department of Microbial Bioactive Compounds, Interfaculty Institute for Microbiology and Infection Medicine, University of Tübingen, 72076 Tübingen, Germany
| | - Chambers C Hughes
- Department of Microbial Bioactive Compounds, Interfaculty Institute for Microbiology and Infection Medicine, University of Tübingen, 72076 Tübingen, Germany.,Cluster of Excellence EXC 2124: Controlling Microbes to Fight Infection, University of Tübingen, 72076 Tübingen, Germany.,German Center for Infection Research, Partner Site Tübingen, 72076 Tübingen, Germany
| | - Heike Brötz-Oesterhelt
- Department of Microbial Bioactive Compounds, Interfaculty Institute for Microbiology and Infection Medicine, University of Tübingen, 72076 Tübingen, Germany.,Cluster of Excellence EXC 2124: Controlling Microbes to Fight Infection, University of Tübingen, 72076 Tübingen, Germany.,German Center for Infection Research, Partner Site Tübingen, 72076 Tübingen, Germany
| | - Robin Teufel
- Pharmaceutical Biology, Department of Pharmaceutical Sciences, Klingelbergstrasse 50, University of Basel, 4056 Basel, Switzerland
| |
Collapse
|
4
|
Mendes SS, Marques J, Mesterházy E, Straetener J, Arts M, Pissarro T, Reginold J, Berscheid A, Bornikoel J, Kluj RM, Mayer C, Oesterhelt F, Friães S, Royo B, Schneider T, Brötz-Oesterhelt H, Romão CC, Saraiva LM. Synergetic Antimicrobial Activity and Mechanism of Clotrimazole-Linked CO-Releasing Molecules. ACS Bio Med Chem Au 2022; 2:419-436. [PMID: 35996473 PMCID: PMC9389576 DOI: 10.1021/acsbiomedchemau.2c00007] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
![]()
Several metal-based
carbon monoxide-releasing molecules (CORMs)
are active CO donors with established antibacterial activity. Among
them, CORM conjugates with azole antibiotics of type [Mn(CO)3(2,2′-bipyridyl)(azole)]+ display important synergies
against several microbes. We carried out a structure–activity
relationship study based upon the lead structure of [Mn(CO)3(Bpy)(Ctz)]+ by producing clotrimazole (Ctz) conjugates
with varying metal and ligands. We concluded that the nature of the
bidentate ligand strongly influences the bactericidal activity, with
the substitution of bipyridyl by small bicyclic ligands leading to
highly active clotrimazole conjugates. On the contrary, the metal
did not influence the activity. We found that conjugate [Re(CO)3(Bpy)(Ctz)]+ is more than the sum of its parts:
while precursor [Re(CO)3(Bpy)Br] has no antibacterial activity
and clotrimazole shows only moderate minimal inhibitory concentrations,
the potency of [Re(CO)3(Bpy)(Ctz)]+ is one order
of magnitude higher than that of clotrimazole, and the spectrum of
bacterial target species includes Gram-positive and Gram-negative
bacteria. The addition of [Re(CO)3(Bpy)(Ctz)]+ to Staphylococcus aureus causes a
general impact on the membrane topology, has inhibitory effects on
peptidoglycan biosynthesis, and affects energy functions. The mechanism
of action of this kind of CORM conjugates involves a sequence of events
initiated by membrane insertion, followed by membrane disorganization,
inhibition of peptidoglycan synthesis, CO release, and break down
of the membrane potential. These results suggest that conjugation
of CORMs to known antibiotics may produce useful structures with synergistic
effects that increase the conjugate’s activity relative to
that of the antibiotic alone.
Collapse
Affiliation(s)
- Sofia S Mendes
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Avenida da República (EAN), 2780-157 Oeiras, Portugal
| | - Joana Marques
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Avenida da República (EAN), 2780-157 Oeiras, Portugal
| | - Edit Mesterházy
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Avenida da República (EAN), 2780-157 Oeiras, Portugal
| | - Jan Straetener
- Interfaculty Institute of Microbiology and Infection Medicine, Dept. of Microbial Bioactive Compounds, Cluster of Excellence Controlling Microbes to Fight Infection. University of Tuebingen, Auf der Morgenstelle 28, 72070 Tuebingen, Germany
| | - Melina Arts
- Institute for Pharmaceutical Microbiology, University of Bonn, University Clinic Bonn, Meckenheimer Allee 168, 53115 Bonn, Germany
| | - Teresa Pissarro
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Avenida da República (EAN), 2780-157 Oeiras, Portugal
| | - Jorgina Reginold
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Avenida da República (EAN), 2780-157 Oeiras, Portugal
| | - Anne Berscheid
- Interfaculty Institute of Microbiology and Infection Medicine, Dept. of Microbial Bioactive Compounds, Cluster of Excellence Controlling Microbes to Fight Infection. University of Tuebingen, Auf der Morgenstelle 28, 72070 Tuebingen, Germany
| | - Jan Bornikoel
- Interfaculty Institute of Microbiology and Infection Medicine, Dept. of Microbial Bioactive Compounds, Cluster of Excellence Controlling Microbes to Fight Infection. University of Tuebingen, Auf der Morgenstelle 28, 72070 Tuebingen, Germany
| | - Robert M Kluj
- Institute of Microbiology and Infection Medicine, Dept. of Organismic Interactions, University of Tuebingen, Auf der Morgenstelle 28, 72070 Tuebingen, Germany
| | - Christoph Mayer
- Institute of Microbiology and Infection Medicine, Dept. of Organismic Interactions, University of Tuebingen, Auf der Morgenstelle 28, 72070 Tuebingen, Germany
| | - Filipp Oesterhelt
- Interfaculty Institute of Microbiology and Infection Medicine, Dept. of Microbial Bioactive Compounds, Cluster of Excellence Controlling Microbes to Fight Infection. University of Tuebingen, Auf der Morgenstelle 28, 72070 Tuebingen, Germany
| | - Sofia Friães
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Avenida da República (EAN), 2780-157 Oeiras, Portugal
| | - Beatriz Royo
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Avenida da República (EAN), 2780-157 Oeiras, Portugal
| | - Tanja Schneider
- Institute for Pharmaceutical Microbiology, University of Bonn, University Clinic Bonn, Meckenheimer Allee 168, 53115 Bonn, Germany
| | - Heike Brötz-Oesterhelt
- Interfaculty Institute of Microbiology and Infection Medicine, Dept. of Microbial Bioactive Compounds, Cluster of Excellence Controlling Microbes to Fight Infection. University of Tuebingen, Auf der Morgenstelle 28, 72070 Tuebingen, Germany
| | - Carlos C Romão
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Avenida da República (EAN), 2780-157 Oeiras, Portugal
| | - Lígia M Saraiva
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Avenida da República (EAN), 2780-157 Oeiras, Portugal
| |
Collapse
|
5
|
Thoma L, Vollmer B, Oesterhelt F, Muth G. Live-cell imaging of Streptomyces conjugation. Int J Med Microbiol 2019; 309:338-343. [PMID: 31175019 DOI: 10.1016/j.ijmm.2019.05.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 05/06/2019] [Accepted: 05/26/2019] [Indexed: 11/19/2022] Open
Abstract
Time-lapse imaging of conjugative plasmid transfer in Streptomyces revealed intriguing insights into the unique two-step conjugation process of this Gram+ mycelial soil bacterium. Differentially labelling of donor and recipient strains with distinct fluorescent proteins allowed the visualization of plasmid transfer in living mycelium. In nearly all observed matings, plasmid transfer occurred when donor and recipient hyphae made intimate contact at the lateral walls. Plasmid transfer does not involve a complete fusion of donor and recipient hyphae, but depends on a pore formed by the FtsK-like DNA translocase TraB. Following the initial transfer at the contact site of donor and recipient, the plasmids spread within the recipient mycelium by invading neighboring compartments, separated by cross walls. Intra-mycelial plasmid spreading depends on a septal cross wall localized multi-protein DNA translocation apparatus consisting of TraB and several Spd proteins and is abolished in a spd mutant. The ability to spread within the recipient mycelium is a crucial adaptation to the mycelial life style of Streptomyces, potentiating the efficiency of plasmid transfer.
Collapse
Affiliation(s)
- L Thoma
- Interfakultäres Institut für Mikrobiologie und Infektionsmedizin Tübingen IMIT, Mikrobiologie/Biotechnologie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 28, 72076, Tuebingen, Germany
| | - B Vollmer
- Interfakultäres Institut für Mikrobiologie und Infektionsmedizin Tübingen IMIT, Mikrobiologie/Biotechnologie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 28, 72076, Tuebingen, Germany
| | - F Oesterhelt
- Interfakultäres Institut für Mikrobiologie und Infektionsmedizin Tübingen IMIT, Mikrobielle Wirkstoffe, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 28, 72076, Tübingen, Germany
| | - G Muth
- Interfakultäres Institut für Mikrobiologie und Infektionsmedizin Tübingen IMIT, Mikrobiologie/Biotechnologie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 28, 72076, Tuebingen, Germany.
| |
Collapse
|
6
|
Bronder AM, Bieker A, Elter S, Etzkorn M, Häussinger D, Oesterhelt F. Oriented Membrane Protein Reconstitution into Tethered Lipid Membranes for AFM Force Spectroscopy. Biophys J 2017; 111:1925-1934. [PMID: 27806274 DOI: 10.1016/j.bpj.2016.08.051] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Revised: 08/21/2016] [Accepted: 08/22/2016] [Indexed: 12/11/2022] Open
Abstract
Membrane proteins act as a central interface between the extracellular environment and the intracellular response and as such represent one of the most important classes of drug targets. The characterization of the molecular properties of integral membrane proteins, such as topology and interdomain interaction, is key to a fundamental understanding of their function. Atomic force microscopy (AFM) and force spectroscopy have the intrinsic capabilities of investigating these properties in a near-native setting. However, atomic force spectroscopy of membrane proteins is traditionally carried out in a crystalline setup. Alternatively, model membrane systems, such as tethered bilayer membranes, have been developed for surface-dependent techniques. While these setups can provide a more native environment, data analysis may be complicated by the normally found statistical orientation of the reconstituted protein in the model membrane. We have developed a model membrane system that enables the study of membrane proteins in a defined orientation by single-molecule force spectroscopy. Our approach is demonstrated using cell-free expressed bacteriorhodopsin coupled to a quartz glass surface in a defined orientation through a protein anchor and reconstituted inside an artificial membrane system. This approach offers an effective way to study membrane proteins in a planar lipid bilayer. It can be easily transferred to all membrane proteins that possess a suitable tag and can be reconstituted into a lipid bilayer. In this respect, we anticipate that this technique may contribute important information on structure, topology, and intra- and intermolecular interactions of other seven-transmembrane helical receptors.
Collapse
Affiliation(s)
- Anna M Bronder
- Institut für Physikalische Biologie, Heinrich-Heine-Universität, Düsseldorf, Germany.
| | - Adeline Bieker
- Institut für Physikalische Biologie, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Shantha Elter
- Institut für Physikalische Biologie, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Manuel Etzkorn
- Institut für Physikalische Biologie, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Dieter Häussinger
- Clinic for Gastroenterology, Hepatology and Infectiology, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Filipp Oesterhelt
- Institut für Physikalische Biologie, Heinrich-Heine-Universität, Düsseldorf, Germany; Department for Microbial Bioactive Compounds, Interfaculty Institute for Microbiology and Infection Medicine, University of Tuebingen, Tuebingen, Germany
| |
Collapse
|
7
|
von Rybinski W, Jabnoun M, van Megen J, Oesterhelt F, Seidel C. Structures of adsorption layers of surfactant mixtures on nonpolar solid surfaces. Colloid Polym Sci 2015. [DOI: 10.1007/s00396-015-3774-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
8
|
Brener O, Dunkelmann T, Gremer L, van Groen T, Mirecka EA, Kadish I, Willuweit A, Kutzsche J, Jürgens D, Rudolph S, Tusche M, Bongen P, Pietruszka J, Oesterhelt F, Langen KJ, Demuth HU, Janssen A, Hoyer W, Funke SA, Nagel-Steger L, Willbold D. QIAD assay for quantitating a compound's efficacy in elimination of toxic Aβ oligomers. Sci Rep 2015; 5:13222. [PMID: 26394756 PMCID: PMC4585794 DOI: 10.1038/srep13222] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [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: 05/07/2015] [Accepted: 07/21/2015] [Indexed: 02/07/2023] Open
Abstract
Strong evidence exists for a central role of amyloid β-protein (Aβ) oligomers in the pathogenesis of Alzheimer’s disease. We have developed a fast, reliable and robust in vitro assay, termed QIAD, to quantify the effect of any compound on the Aβ aggregate size distribution. Applying QIAD, we studied the effect of homotaurine, scyllo-inositol, EGCG, the benzofuran derivative KMS88009, ZAβ3W, the D-enantiomeric peptide D3 and its tandem version D3D3 on Aβ aggregation. The predictive power of the assay for in vivo efficacy is demonstrated by comparing the oligomer elimination efficiency of D3 and D3D3 with their treatment effects in animal models of Alzheimer´s disease.
Collapse
Affiliation(s)
- Oleksandr Brener
- Institute of Complex Systems, Structural Biochemistry (ICS-6), Research Centre Jülich, 52425 Jülich, Germany.,Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany
| | - Tina Dunkelmann
- Institute of Complex Systems, Structural Biochemistry (ICS-6), Research Centre Jülich, 52425 Jülich, Germany
| | - Lothar Gremer
- Institute of Complex Systems, Structural Biochemistry (ICS-6), Research Centre Jülich, 52425 Jülich, Germany.,Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany
| | - Thomas van Groen
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Ewa A Mirecka
- Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany
| | - Inga Kadish
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Antje Willuweit
- Institute of Neuroscience and Medicine (INM-4), Research Centre Jülich (FZJ), 52425 Jülich, Germany
| | - Janine Kutzsche
- Institute of Complex Systems, Structural Biochemistry (ICS-6), Research Centre Jülich, 52425 Jülich, Germany
| | - Dagmar Jürgens
- Institute of Complex Systems, Structural Biochemistry (ICS-6), Research Centre Jülich, 52425 Jülich, Germany
| | - Stephan Rudolph
- Institute of Complex Systems, Structural Biochemistry (ICS-6), Research Centre Jülich, 52425 Jülich, Germany
| | - Markus Tusche
- Institute of Complex Systems, Structural Biochemistry (ICS-6), Research Centre Jülich, 52425 Jülich, Germany
| | - Patrick Bongen
- Institute for Bioorganic Chemistry, Heinrich-Heine-Universität Düsseldorf, 52426 Jülich, Germany
| | - Jörg Pietruszka
- Institute for Bioorganic Chemistry, Heinrich-Heine-Universität Düsseldorf, 52426 Jülich, Germany.,Institut für Bio- und Geowissenschaften: Biotechnologie (IBG-1), Forschungszentrum Jülich, 52428 Jülich, Germany
| | - Filipp Oesterhelt
- Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany
| | - Karl-Josef Langen
- Institute of Neuroscience and Medicine (INM-4), Research Centre Jülich (FZJ), 52425 Jülich, Germany
| | - Hans-Ulrich Demuth
- Fraunhofer Institute for Cell Therapy and Immunology, Dep. Molecular Drug Biochemistry and Therapy, 06120 Halle, Germany
| | - Arnold Janssen
- Institute of Mathematics, Lehrstuhl für Statistik und Wahrscheinlichkeitstheorie, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany
| | - Wolfgang Hoyer
- Institute of Complex Systems, Structural Biochemistry (ICS-6), Research Centre Jülich, 52425 Jülich, Germany.,Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany
| | - Susanne A Funke
- Institute of Complex Systems, Structural Biochemistry (ICS-6), Research Centre Jülich, 52425 Jülich, Germany.,Bioanalytik, Hochschule für Angewandte Wissenschaften, Coburg, Germany
| | - Luitgard Nagel-Steger
- Institute of Complex Systems, Structural Biochemistry (ICS-6), Research Centre Jülich, 52425 Jülich, Germany.,Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany
| | - Dieter Willbold
- Institute of Complex Systems, Structural Biochemistry (ICS-6), Research Centre Jülich, 52425 Jülich, Germany.,Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany
| |
Collapse
|
9
|
Mirecka EA, Gremer L, Schiefer S, Oesterhelt F, Stoldt M, Willbold D, Hoyer W. Engineered aggregation inhibitor fusion for production of highly amyloidogenic human islet amyloid polypeptide. J Biotechnol 2014; 191:221-7. [DOI: 10.1016/j.jbiotec.2014.06.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 05/27/2014] [Accepted: 06/04/2014] [Indexed: 01/14/2023]
|
10
|
Bronder A, Roychoudhury A, Häussinger D, Oesterhelt F. Atomic force measurements on the specifically orientated membrane protein TGR5 reconstituted inside a tethered bilayer lipid membrane. Eur J Med Res 2014. [PMCID: PMC4118435 DOI: 10.1186/2047-783x-19-s1-s11] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
11
|
Roychoudhury A, Bieker A, Häussinger D, Oesterhelt F. Membrane protein stability depends on the concentration of compatible solutes--a single molecule force spectroscopic study. Biol Chem 2014; 394:1465-74. [PMID: 24021596 DOI: 10.1515/hsz-2013-0173] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Accepted: 09/04/2013] [Indexed: 11/15/2022]
Abstract
Compatible solutes are small, uncharged, zwitter ionic, osmotically active molecules produced and accumulated by microorganisms inside their cell to counteract different kinds of environmental stress. They enhance protein stability without interfering with the metabolic pathways even at molar concentrations. In this paper, we report the stabilizing effects of compatible solutes, ectoine, betaine and taurine on membrane protein bacteriorhodopsin at different concentrations. Using atomic force microscopy based single molecule force spectroscopy the impact of the osmolytes was quantified by measuring the forces required to pull the protein out of the membrane and the change in the persistence lengths of the unfolded polypeptide chain. Increase in unfolding forces were observed, indicating the strengthening of intramolecular interactions, which are vital for protein stability. The decrease in persistence lengths was recorded and showed increasing tendencies of the polypeptide strand to coil up. Interestingly, it was revealed that these molecules have different stabilizing effects on protein unfolding at different concentrations. The results show that the unfolding of single protein provides insight to the structure-dynamic relationship between the protein and compatible solute molecules at sub-nanometer scale. This also helps to understand the molecular mechanism involved in protein stabilization by organic osmolytes.
Collapse
|
12
|
Arslan Z, Wurm R, Brener O, Ellinger P, Nagel-Steger L, Oesterhelt F, Schmitt L, Willbold D, Wagner R, Gohlke H, Smits SHJ, Pul U. Double-strand DNA end-binding and sliding of the toroidal CRISPR-associated protein Csn2. Nucleic Acids Res 2013; 41:6347-59. [PMID: 23625968 PMCID: PMC3695520 DOI: 10.1093/nar/gkt315] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [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] [Indexed: 12/26/2022] Open
Abstract
The adaptive immunity of bacteria against foreign nucleic acids, mediated by CRISPR (clustered regularly interspaced short palindromic repeats), relies on the specific incorporation of short pieces of the invading foreign DNA into a special genomic locus, termed CRISPR array. The stored sequences (spacers) are subsequently used in the form of small RNAs (crRNAs) to interfere with the target nucleic acid. We explored the DNA-binding mechanism of the immunization protein Csn2 from the human pathogen Streptococcus agalactiae using different biochemical techniques, atomic force microscopic imaging and molecular dynamics simulations. The results demonstrate that the ring-shaped Csn2 tetramer binds DNA ends through its central hole and slides inward, likely by a screw motion along the helical path of the enclosed DNA. The presented data indicate an accessory function of Csn2 during integration of exogenous DNA by end-joining.
Collapse
Affiliation(s)
- Zihni Arslan
- Institut für Physikalische Biologie, Heinrich-Heine-Universität, Universitätsstr. 1, 40225 Düsseldorf, Germany
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Roychoudhury A, Haussinger D, Oesterhelt F. Effect of the compatible solute ectoine on the stability of the membrane proteins. Protein Pept Lett 2012; 19:791-4. [PMID: 22702895 DOI: 10.2174/092986612801619570] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 03/02/2012] [Accepted: 03/02/2012] [Indexed: 11/22/2022]
Abstract
Mechanical single molecule techniques offer exciting possibilities for investigating protein folding and stability in native environments at sub-nanometer resolutions. Compatible solutes show osmotic activity which even at molar concentrations do not interfere with cell metabolism. They are known to protect proteins against external stress like temperature, high salt concentrations and dehydrating conditions. We studied the impact of the compatible solute ectoine (1M) on membrane proteins by analyzing the mechanical properties of Bacteriorhodopsin (BR) in its presence and absence by single molecule force spectroscopy. The unfolding experiments on BR revealed that ectoine decreases the persistence length of its polypeptide chain thereby increasing its tendency to coil up. In addition, we found higher unfolding forces indicating strengthening of those intra molecular interactions which are crucial for stability. This shows that force spectroscopy is well suited to study the effect of compatible solutes to stabilize membrane proteins against unfolding. In addition, it may lead to a better understanding of their detailed mechanism of action.
Collapse
Affiliation(s)
- Arpita Roychoudhury
- Institute for Physical Biology, Universitatsstr. 1; Geb. 26.12.U1.78, Heinrich Heine University, 40225 Dusseldorf, Germany.
| | | | | |
Collapse
|
14
|
|
15
|
Abstract
Scanning probe microscopy-based techniques can address and manipulate individual molecules. This makes it possible to use them for building nanostructures by assembling single molecules. Recently the formation of surface structures by positioning single molecules with the Atomic Force Microscope (AFM) was demonstrated on an irreversible delivery process. This inherits the drawback, that the transfer has to occur between differently functionalized surfaces and allows no proofreading of the built structures. Here we demonstrate a procedure for directed deposition of single DNA molecules, which intrinsically allows a reversible positioning. This method uses specific interactions between complementary DNA oligonucleotides for symmetric coupling of the transport molecules to the support and AFM tip, respectively. Thus, it allows for a simple "drag-and-drop" procedure, which relies on the statistical breakage of the molecular interaction under a force load. In addition, the delivery of the transport molecules was observed in real-time by single-molecule fluorescence microscopy.
Collapse
Affiliation(s)
- Richard Janissen
- Institute of Molecular Physical Chemistry, Heinrich-Heine University, Universitätsstrasse 1, 40225 Düsseldorf, Germany
| | | |
Collapse
|
16
|
Oberbarnscheidt L, Janissen R, Oesterhelt F. Direct and model free calculation of force-dependent dissociation rates from force spectroscopic data. Biophys J 2010; 97:L19-21. [PMID: 19883578 DOI: 10.1016/j.bpj.2009.08.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2008] [Revised: 07/31/2009] [Accepted: 08/03/2009] [Indexed: 11/27/2022] Open
Abstract
Force spectroscopy allows testing the free energy landscapes of molecular interactions. Usually, the dependency of the most probable rupture force on the force rate or the shape of the rupture force histogram is fitted with different models that contain approximations and basic assumptions. We present a simple and model free approach to extract the force-dependent dissociation rates directly from the force curve data. Simulations show that the dissociation rates at any force are given directly by the ratio of the number of detected rupture events to the time this force was acting on the bond. To calculate these total times of acting forces, all force curve data points of all curves measured are taken into account, which significantly increases the amount of information which is considered for data analysis compared to other methods. Moreover, by providing force-dependent dissociation rates this method allows direct testing and validating of any energy landscape model.
Collapse
Affiliation(s)
- Leoni Oberbarnscheidt
- Institute of Molecular Physical Chemistry, Heinrich-Heine University, Düsseldorf, Germany
| | | | | |
Collapse
|
17
|
Oberbarnscheidt L, Janissen R, Martell S, Engelhard M, Oesterhelt F. Single-Molecule Force Spectroscopy Measures Structural Changes Induced by Light Activation and Transducer Binding in Sensory Rhodopsin II. J Mol Biol 2009; 394:383-90. [DOI: 10.1016/j.jmb.2009.07.083] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Revised: 07/27/2009] [Accepted: 07/28/2009] [Indexed: 11/16/2022]
|
18
|
Oesterhelt F. Direct and Model Free Calculation of Force Dependent Dissociation Rates and Free Energy Barriers from Force Spectroscopic Data. Biophys J 2009. [DOI: 10.1016/j.bpj.2008.12.3400] [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: 10/21/2022] Open
|
19
|
Oberbarnscheidt L, Martell S, Engelhard M, Oesterhelt F. Atomic Force Spectroscopy Measures Light Activation And Transducer Binding Induced Structural Changes In The Sensory Rhodopsin II. Biophys J 2009. [DOI: 10.1016/j.bpj.2008.12.2930] [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: 11/25/2022] Open
|
20
|
Cisneros DA, Oberbarnscheidt L, Pannier A, Klare JP, Helenius J, Engelhard M, Oesterhelt F, Muller DJ. Transducer Binding Establishes Localized Interactions to Tune Sensory Rhodopsin II. Structure 2008; 16:1206-13. [DOI: 10.1016/j.str.2008.04.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2008] [Revised: 04/11/2008] [Accepted: 04/11/2008] [Indexed: 12/13/2022]
|
21
|
Kudryavtsev V, Felekyan S, Woźniak AK, König M, Sandhagen C, Kühnemuth R, Seidel CAM, Oesterhelt F. Monitoring dynamic systems with multiparameter fluorescence imaging. Anal Bioanal Chem 2006; 387:71-82. [PMID: 17160654 DOI: 10.1007/s00216-006-0917-0] [Citation(s) in RCA: 32] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2006] [Revised: 10/05/2006] [Accepted: 10/09/2006] [Indexed: 10/23/2022]
Abstract
A new general strategy based on the use of multiparameter fluorescence detection (MFD) to register and quantitatively analyse fluorescence images is introduced. Multiparameter fluorescence imaging (MFDi) uses pulsed excitation, time-correlated single-photon counting and a special pixel clock to simultaneously monitor the changes in the eight-dimensional fluorescence information (fundamental anisotropy, fluorescence lifetime, fluorescence intensity, time, excitation spectrum, fluorescence spectrum, fluorescence quantum yield, distance between fluorophores) in real time. The three spatial coordinates are also stored. The most statistically efficient techniques known from single-molecule spectroscopy are used to estimate fluorescence parameters of interest for all pixels, not just for the regions of interest. Their statistical significance is judged from a stack of two-dimensional histograms. In this way, specific pixels can be selected for subsequent pixel-based subensemble analysis in order to improve the statistical accuracy of the parameters estimated. MFDi avoids the need for sequential measurements, because the registered data allow one to perform many analysis techniques, such as fluorescence-intensity distribution analysis (FIDA) and fluorescence correlation spectroscopy (FCS), in an off-line mode. The limitations of FCS for counting molecules and monitoring dynamics are discussed. To demonstrate the ability of our technique, we analysed two systems: (i) interactions of the fluorescent dye Rhodamine 110 inside and outside of a glutathione sepharose bead, and (ii) microtubule dynamics in live yeast cells of Schizosaccharomyces pombe using a fusion protein of Green Fluorescent Protein (GFP) with Minichromosome Altered Loss Protein 3 (Mal3), which is involved in the dynamic cycle of polymerising and depolymerising microtubules.
Collapse
Affiliation(s)
- Volodymyr Kudryavtsev
- Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstrasse 1, 40225, Düsseldorf, Germany
| | | | | | | | | | | | | | | |
Collapse
|
22
|
Woźniak AK, Nottrott S, Kühn-Hölsken E, Schröder GF, Grubmüller H, Lührmann R, Seidel CAM, Oesterhelt F. Detecting protein-induced folding of the U4 snRNA kink-turn by single-molecule multiparameter FRET measurements. RNA 2005; 11:1545-54. [PMID: 16199764 PMCID: PMC1370838 DOI: 10.1261/rna.2950605] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The kink-turn (k-turn), a new RNA structural motif found in the spliceosome and the ribosome, serves as a specific protein recognition element and as a structural building block. While the structure of the spliceosomal U4 snRNA k-turn/15.5K complex is known from a crystal structure, it is unclear whether the k-turn also exists in this folded conformation in the free U4 snRNA. Thus, we investigated the U4 snRNA k-turn by single-molecule FRET measurements in the absence and presence of the 15.5K protein and its dependence on the Na(+) and Mg(2+) ion concentration. We show that the unfolded U4 snRNA k-turn introduces a kink of 85 degrees +/- 15 degrees in an RNA double helix. While Na(+) and Mg(2+) ions induce this more open conformation of the k-turn, binding of the 15.5K protein was found to induce the tightly kinked conformation in the RNA that increases the kink to 52 degrees +/- 15 degrees . By comparison of the measured FRET distances with a computer-modeled structure, we show that this strong kink is due to the k-turn motif adopting its folded conformation. Thus, in the free U4 snRNA, the k-turn exists only in an unfolded conformation, and its folding is induced by binding of the 15.5K protein.
Collapse
Affiliation(s)
- Anna K Woźniak
- Heinrich-Heine-Universität Düsseldorf, Institut für molekulare Physikalische Chemie, 40225 Düsseldorf, Germany
| | | | | | | | | | | | | | | |
Collapse
|
23
|
Blank K, Mai T, Gilbert I, Schiffmann S, Rankl J, Zivin R, Tackney C, Nicolaus T, Spinnler K, Oesterhelt F, Benoit M, Clausen-Schaumann H, Gaub HE. A force-based protein biochip. Proc Natl Acad Sci U S A 2003; 100:11356-60. [PMID: 12975526 PMCID: PMC208761 DOI: 10.1073/pnas.1934928100] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [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: 11/18/2022] Open
Abstract
A parallel assay for the quantification of single-molecule binding forces was developed based on differential unbinding force measurements where ligand-receptor interactions are compared with the unzipping forces of DNA hybrids. Using the DNA zippers as molecular force sensors, the efficient discrimination between specific and nonspecific interactions was demonstrated for small molecules binding to specific receptors, as well as for protein-protein interactions on protein arrays. Finally, an antibody sandwich assay with different capture antibodies on one chip surface and with the detection antibodies linked to a congruent surface via the DNA zippers was used to capture and quantify a recombinant hepatitis C antigen from solution. In this case, the DNA zippers enable not only discrimination between specific and nonspecific binding, but also allow for the local application of detection antibodies, thereby eliminating false-positive results caused by cross-reactive antibodies and nonspecific binding.
Collapse
Affiliation(s)
- K Blank
- nanotype, Lochhamer Schlag 12, 82166 Gräfelfing, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Müller DJ, Kessler M, Oesterhelt F, Möller C, Oesterhelt D, Gaub H. Stability of bacteriorhodopsin alpha-helices and loops analyzed by single-molecule force spectroscopy. Biophys J 2002; 83:3578-88. [PMID: 12496125 PMCID: PMC1302433 DOI: 10.1016/s0006-3495(02)75358-7] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.3] [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: 11/21/2022] Open
Abstract
The combination of high-resolution atomic force microscopy imaging and single-molecule force spectroscopy allows the identification, selection, and mechanical investigation of individual proteins. In a recent paper we had used this technique to unfold and extract single bacteriorhodopsins (BRs) from native purple membrane patches. We show that subsets of the unfolding spectra can be classified and grouped to reveal detailed insight into the individualism of the unfolding pathways. We have further developed this technique and analysis to report here on the influence of pH effects and local mutations on the stability of individual structural elements of BR against mechanical unfolding. We found that, although the seven transmembrane alpha-helices predominantly unfold in pairs, each of the helices may also unfold individually and in some cases even only partially. Additionally, intermittent states in the unfolding process were found, which are associated with the stretching of the extracellular loops connecting the alpha-helices. This suggests that polypeptide loops potentially act as a barrier to unfolding and contribute significantly to the structural stability of BR. Chemical removal of the Schiff base, the covalent linkage of the photoactive retinal to the helix G, resulted in a predominantly two-step unfolding of this helix. It is concluded that the covalent linkage of the retinal to helix G stabilizes the structure of BR. Trapping mutant D96N in the M state of the proton pumping photocycle did not affect the unfolding barriers of BR.
Collapse
Affiliation(s)
- Daniel J Müller
- Max-Planck-Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany.
| | | | | | | | | | | |
Collapse
|
25
|
Abstract
Atomic force microscopy (AFM) allows the observation of surface structures of purple membrane (PM) in buffer solution with subnanometer resolution. This offers the possibility to classify the major conformations of the native bacteriorhodopsin (BR) surfaces and to map the variability of individual polypeptide loops connecting transmembrane alpha-helices of BR. The position, the variability and the flexibility of these loops depend on the packing arrangement of BR molecules in the lipid bilayer with significant differences observed between the trigonal and orthorhombic crystal forms. Cleavage of the Schiff base bond leads to a disassembly of the trigonal PM crystal, which is restored by regenerating the bleached PM. The combination of single molecule AFM imaging and single molecule force-spectroscopy provides an unique insight into the interactions between individual BR molecules and the PM, and between secondary structure elements within BR.
Collapse
Affiliation(s)
- D J Müller
- M.E. Müller-Institute for Structural Biology, Biozentrum, University of Basel, Klingelkbergstr. 70, CH-4056 Basel, Switzerland.
| | | | | | | | | | | | | |
Collapse
|
26
|
Abstract
Atomic force microscopy and single-molecule force spectroscopy were combined to image and manipulate purple membrane patches from Halobacterium salinarum. Individual bacteriorhodopsin molecules were first localized and then extracted from the membrane; the remaining vacancies were imaged again. Anchoring forces between 100 and 200 piconewtons for the different helices were found. Upon extraction, the helices were found to unfold. The force spectra revealed the individuality of the unfolding pathways. Helices G and F as well as helices E and D always unfolded pairwise, whereas helices B and C occasionally unfolded one after the other. Experiments with cleaved loops revealed the origin of the individuality: stabilization of helix B by neighboring helices.
Collapse
Affiliation(s)
- F Oesterhelt
- CeNS and Lehrstuhl für angewandte Physik, Ludwig Maximilians-Universität München, Amalienstrasse 54, 80799 München, Germany
| | | | | | | | | | | |
Collapse
|
27
|
Abstract
Single-molecule atomic force microscopy (AFM) was used to investigate the mechanical properties of titin, the giant sarcomeric protein of striated muscle. Individual titin molecules were repeatedly stretched, and the applied force was recorded as a function of the elongation. At large extensions, the restoring force exhibited a sawtoothlike pattern, with a periodicity that varied between 25 and 28 nanometers. Measurements of recombinant titin immunoglobulin segments of two different lengths exhibited the same pattern and allowed attribution of the discontinuities to the unfolding of individual immunoglobulin domains. The forces required to unfold individual domains ranged from 150 to 300 piconewtons and depended on the pulling speed. Upon relaxation, refolding of immunoglobulin domains was observed.
Collapse
Affiliation(s)
- M Rief
- Lehrstuhl für Angewandte Physik, München, Germany
| | | | | | | | | |
Collapse
|
28
|
Abstract
Recent developments in piconewton instrumentation allow the manipulation of single molecules and measurements of intermolecular as well as intramolecular forces. Dextran filaments linked to a gold surface were probed with the atomic force microscope tip by vertical stretching. At low forces the deformation of dextran was found to be dominated by entropic forces and can be described by the Langevin function with a 6 angstrom Kuhn length. At elevated forces the strand elongation was governed by a twist of bond angles. At higher forces the dextran filaments underwent a distinct conformational change. The polymer stiffened and the segment elasticity was dominated by the bending of bond angles. The conformational change was found to be reversible and was corroborated by molecular dynamics calculations.
Collapse
Affiliation(s)
- M Rief
- M. Rief, F. Oesterhelt, H. E. Gaub, Lehrstuhl fur Angewandte Physik, Ludwig-Maximilians-Universitat, 80799 Munchen, Germany. B. Heymann, Theoretische Biophysik, Institut fur Medizinische Optik, Ludwig-Maximilians-Universitat 80333 Munchen, Germany
| | | | | | | |
Collapse
|