101
|
Cornet SHV, Snel SJE, Schreuders FKG, van der Sman RGM, Beyrer M, van der Goot AJ. Thermo-mechanical processing of plant proteins using shear cell and high-moisture extrusion cooking. Crit Rev Food Sci Nutr 2021; 62:3264-3280. [PMID: 33406893 DOI: 10.1080/10408398.2020.1864618] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Consumption of plant-based meat analogues offers a way to reduce the environmental footprint of the human diet. High-moisture extrusion cooking (HMEC) and shear cell processing both rely on thermo-mechanical treatment of proteins to product fibrous meat-like products. However, the mechanisms underlying these processes are not well understood. In this review we discuss the effect of thermo-mechanical processing on the physicochemical properties and phase behavior of proteins and protein mixtures. The HMEC and shear cell processes are comparable in their basic unit operations, which are (1) mixing and hydration, (2) thermo-mechanical treatment, and (3) cooling. An often overlooked part of the extruder that could be crucial to fibrillation is the so-called breaker plate, which is situated between the barrel and die sections. We found a lack of consensus on the effect of heat on protein-protein interactions, and that the experimental tools to study protein-protein interactions are limited. The different mechanisms for structure formation proposed in literature all consider the deformation and alignment of the melt. However, the mechanisms differ in their underlying assumptions. Further investigation using novel and dedicated tools is required to fully understand these thermo-mechanical processes.
Collapse
Affiliation(s)
- Steven H V Cornet
- Food Process Engineering, Agrotechnology and Food Sciences Group, Wageningen University & Research, Wageningen, The Netherlands.,Food and Biobased Research, Wageningen University & Research, Wageningen, The Netherlands
| | - Silvia J E Snel
- Food Process Engineering, Agrotechnology and Food Sciences Group, Wageningen University & Research, Wageningen, The Netherlands.,Food Process Engineering, School of Engineering, Sion, The Netherlands
| | - Floor K G Schreuders
- Food Process Engineering, Agrotechnology and Food Sciences Group, Wageningen University & Research, Wageningen, The Netherlands
| | - Ruud G M van der Sman
- Food Process Engineering, Agrotechnology and Food Sciences Group, Wageningen University & Research, Wageningen, The Netherlands.,Food and Biobased Research, Wageningen University & Research, Wageningen, The Netherlands
| | - Michael Beyrer
- Food Process Engineering, School of Engineering, Sion, The Netherlands
| | - Atze Jan van der Goot
- Food Process Engineering, Agrotechnology and Food Sciences Group, Wageningen University & Research, Wageningen, The Netherlands
| |
Collapse
|
102
|
Dansuk KC, Keten S. Self-strengthening biphasic nanoparticle assemblies with intrinsic catch bonds. Nat Commun 2021; 12:85. [PMID: 33397979 PMCID: PMC7782701 DOI: 10.1038/s41467-020-20344-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 11/23/2020] [Indexed: 01/06/2023] Open
Abstract
Protein-ligand complexes with catch bonds exhibit prolonged lifetimes when subject to tensile force, which is a desirable yet elusive attribute for man-made nanoparticle interfaces and assemblies. Most designs proposed so far rely on macromolecular linkers with complicated folds rather than particles exhibiting simple dynamic shapes. Here, we establish a scissor-type X-shaped particle design for achieving intrinsic catch bonding ability with tunable force-enhanced lifetimes under thermal excitations. Molecular dynamics simulations are carried out to illustrate equilibrium self-assembly and force-enhanced bond lifetime of dimers and fibers facilitated by secondary interactions that form under tensile force. The non-monotonic force dependence of the fiber breaking kinetics is well-estimated by an analytical model. Our design concepts for shape-changing particles illuminates a path towards novel nanoparticle or colloidal assemblies that have the passive ability to tune the strength of their interfaces with applied force, setting the stage for self-assembling materials with novel mechanical functions and rheological properties.
Collapse
Affiliation(s)
- Kerim C Dansuk
- Department of Mechanical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Sinan Keten
- Department of Mechanical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA.
- Department of Civil & Environmental Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA.
| |
Collapse
|
103
|
Zhai H, Zhang W, Wang L, Putnis CV. Dynamic force spectroscopy for quantifying single-molecule organo–mineral interactions. CrystEngComm 2021. [DOI: 10.1039/d0ce00949k] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Organo–mineral interactions have long been the focus in the fields of biomineralization and geomineralization, since such interactions not only modulate the dynamics of crystal nucleation and growth but may also change crystal phases, morphologies, and structures.
Collapse
Affiliation(s)
- Hang Zhai
- College of Resources and Environment
- Huazhong Agricultural University
- Wuhan 430070
- China
- Department of Plant and Environmental Sciences
| | - Wenjun Zhang
- College of Resources and Environment
- Huazhong Agricultural University
- Wuhan 430070
- China
| | - Lijun Wang
- College of Resources and Environment
- Huazhong Agricultural University
- Wuhan 430070
- China
| | - Christine V. Putnis
- Institut für Mineralogie
- University of Münster
- 48149 Münster
- Germany
- School of Molecular and Life Science
| |
Collapse
|
104
|
Mathelié-Guinlet M, Viela F, Pietrocola G, Speziale P, Dufrêne YF. Nanonewton forces between Staphylococcus aureus surface protein IsdB and vitronectin. NANOSCALE ADVANCES 2020; 2:5728-5736. [PMID: 36133863 PMCID: PMC9419033 DOI: 10.1039/d0na00636j] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Accepted: 10/16/2020] [Indexed: 06/16/2023]
Abstract
Single-molecule experiments have recently revealed that the interaction between staphylococcal surface proteins and their ligands can be extremely strong, equivalent to the strength of covalent bonds. Here, we report on the unusually high binding strength between Staphylococcus aureus iron-regulated surface determinant B (IsdB) and vitronectin (Vn), an essential human blood protein known to interact with bacterial pathogens. The IsdB-Vn interaction is dramatically strengthened by mechanical tension, with forces up to 2000 pN at a loading rate of 105 pN s-1. In line with this, flow experiments show that IsdB-mediated bacterial adhesion to Vn is enhanced by fluid shear stress. The stress-dependent binding of IsdB to Vn is likely to play a role in promoting bacterial adhesion to human cells under fluid shear stress conditions.
Collapse
Affiliation(s)
- Marion Mathelié-Guinlet
- Louvain Institute of Biomolecular Science and Technology, UCLouvain Croix du Sud, 4-5, bte L7.07.07 B-1348 Louvain-la-Neuve Belgium
| | - Felipe Viela
- Louvain Institute of Biomolecular Science and Technology, UCLouvain Croix du Sud, 4-5, bte L7.07.07 B-1348 Louvain-la-Neuve Belgium
| | - Giampiero Pietrocola
- Department of Molecular Medicine, Unit of Biochemistry, University of Pavia Viale Taramelli 3/b 27100 Pavia Italy
| | - Pietro Speziale
- Department of Molecular Medicine, Unit of Biochemistry, University of Pavia Viale Taramelli 3/b 27100 Pavia Italy
| | - Yves F Dufrêne
- Louvain Institute of Biomolecular Science and Technology, UCLouvain Croix du Sud, 4-5, bte L7.07.07 B-1348 Louvain-la-Neuve Belgium
- Walloon Excellence in Life Sciences and Biotechnology (WELBIO) B-1300 Wavre Belgium
| |
Collapse
|
105
|
Mathelié-Guinlet M, Viela F, Alfeo MJ, Pietrocola G, Speziale P, Dufrêne YF. Single-Molecule Analysis Demonstrates Stress-Enhanced Binding between Staphylococcus aureus Surface Protein IsdB and Host Cell Integrins. NANO LETTERS 2020; 20:8919-8925. [PMID: 33237786 DOI: 10.1021/acs.nanolett.0c04015] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Binding of Staphylococcus aureus surface proteins to endothelial cell integrins plays essential roles in host cell adhesion and invasion, eventually leading to life-threatening diseases. The staphylococcal protein IsdB binds to β3-containing integrins through a mechanism that has never been thoroughly investigated. Here, we identify and characterize at the nanoscale a previously undescribed stress-dependent adhesion between IsdB and integrin αVβ3. The strength of single IsdB-αVβ3 interactions is moderate (∼100 pN) under low stress, but it increases dramatically under high stress (∼1000-2000 pN) to exceed the forces traditionally reported for the binding between integrins and Arg-Gly-Asp (RGD) sequences. We suggest a mechanism where high mechanical stress induces conformational changes in the integrin from a low-affinity, weak binding state to a high-affinity, strong binding state. This single-molecule study highlights that direct adhesin-integrin interactions represent potential targets to fight staphylococcal infections.
Collapse
Affiliation(s)
- Marion Mathelié-Guinlet
- Louvain Institute of Biomolecular Science and Technology, UCLouvain, Croix du Sud, 4-5, bte L7.07.07, B-1348 Louvain-la-Neuve, Belgium
| | - Felipe Viela
- Louvain Institute of Biomolecular Science and Technology, UCLouvain, Croix du Sud, 4-5, bte L7.07.07, B-1348 Louvain-la-Neuve, Belgium
| | - Mariangela Jessica Alfeo
- Department of Molecular Medicine, Unit of Biochemistry, University of Pavia, Viale Taramelli 3/b, 27100 Pavia, Italy
| | - Giampiero Pietrocola
- Department of Molecular Medicine, Unit of Biochemistry, University of Pavia, Viale Taramelli 3/b, 27100 Pavia, Italy
| | - Pietro Speziale
- Department of Molecular Medicine, Unit of Biochemistry, University of Pavia, Viale Taramelli 3/b, 27100 Pavia, Italy
| | - Yves F Dufrêne
- Louvain Institute of Biomolecular Science and Technology, UCLouvain, Croix du Sud, 4-5, bte L7.07.07, B-1348 Louvain-la-Neuve, Belgium
| |
Collapse
|
106
|
Martínez‐Tong DE, Pomposo JA, Verde‐Sesto E. Triggering Forces at the Nanoscale: Technologies for Single‐Chain Mechanical Activation and Manipulation. Macromol Rapid Commun 2020; 42:e2000654. [DOI: 10.1002/marc.202000654] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 11/14/2020] [Indexed: 01/05/2023]
Affiliation(s)
- Daniel E. Martínez‐Tong
- Departamento de Polímeros y Materiales Avanzados: Física, Química y Tecnología University of the Basque Country (UPV/EHU) P. Manuel Lardizábal 3 Donostia‐San Sebastián 20018 Spain
- Centro de Física de Materiales (UPV/EHU‐CSIC) P. Manuel Lardizábal 5 San Sebastián 20018 Spain
| | - José A. Pomposo
- Departamento de Polímeros y Materiales Avanzados: Física, Química y Tecnología University of the Basque Country (UPV/EHU) P. Manuel Lardizábal 3 Donostia‐San Sebastián 20018 Spain
- Centro de Física de Materiales (CFM) (CSIC‐UPV/EHU)—Materials Physics Center (MPC) Paseo Manuel de Lardizábal 5 Donostia‐San Sebastián 20018 Spain
- IKERBASQUE—Basque Foundation for Science Plaza Euskadi 5 Bilbao 48009 Spain
| | - Ester Verde‐Sesto
- Centro de Física de Materiales (CFM) (CSIC‐UPV/EHU)—Materials Physics Center (MPC) Paseo Manuel de Lardizábal 5 Donostia‐San Sebastián 20018 Spain
| |
Collapse
|
107
|
Abstract
Mechanical forces and mechanical energy are prevalent in living cells. This may be because mechanical forces and mechanical energy preceded chemical energy at life’s origins. Mechanical energy is more readily available in nonliving systems than the various forms of chemical energy used by living systems. Two possible prebiotic environments that might have provided mechanical energy are hot pools that experience wet/dry cycles and mica sheets as they move, open and shut, as heat pumps or in response to water movements.
Collapse
|
108
|
Li J, Li H. Single molecule force spectroscopy reveals that a two-coordinate ferric site is critical for the folding of holo-rubredoxin. NANOSCALE 2020; 12:22564-22573. [PMID: 33169779 DOI: 10.1039/d0nr06275h] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Metalloproteins play important roles in a wide range of biological processes. The folding process of metalloproteins is complex due to the synergistic effects of the folding of their polypeptide chains and the incorporation of metal cofactors. The folding mechanism of the simplest iron-sulfur protein rubredoxin, which contains one ferric ion coordinated by four cysteinyl sulfurs, is revealed using optical tweezers for the first time. The folding of the rubredoxin polypeptide chain is rapid and robust, while the reconstitution of the iron-sulfur center is greatly dependent upon the coordination state of the ferric ion on the unfolded polypeptide chain. If the ferric ion is coordinated by two neighboring cysteines, rubredoxin can readily fold with the iron-sulfur center fully reconstituted. However, if the ferric ion is only mono-coordinated, rubredoxin can fold but the iron-sulfur center is not reconstituted. Our results suggested that the folding of holo-rubredoxin follows a novel binding-folding-reconstitution mechanism, which is distinct from the folding mechanisms proposed for the folding of metalloproteins. Our study highlights the critical importance of the two-coordinate ferric site in the folding of holo-rubredoxin, which may have some important implications to our understanding of the folding mechanism of more complex metalloproteins in vivo.
Collapse
Affiliation(s)
- Jiayu Li
- Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1, Canada.
| | | |
Collapse
|
109
|
Force-clamp spectroscopy identifies a catch bond mechanism in a Gram-positive pathogen. Nat Commun 2020; 11:5431. [PMID: 33110079 PMCID: PMC7591895 DOI: 10.1038/s41467-020-19216-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 10/01/2020] [Indexed: 01/17/2023] Open
Abstract
Physical forces have profound effects on cellular behavior, physiology, and disease. Perhaps the most intruiguing and fascinating example is the formation of catch-bonds that strengthen cellular adhesion under shear stresses. Today mannose-binding by the Escherichia coli FimH adhesin remains one of the rare microbial catch-bond thoroughly characterized at the molecular level. Here we provide a quantitative demonstration of a catch-bond in living Gram-positive pathogens using force-clamp spectroscopy. We show that the dock, lock, and latch interaction between staphylococcal surface protein SpsD and fibrinogen is strong, and exhibits an unusual catch-slip transition. The bond lifetime first grows with force, but ultimately decreases to behave as a slip bond beyond a critical force (~1 nN) that is orders of magnitude higher than for previously investigated complexes. This catch-bond, never reported for a staphylococcal adhesin, provides the pathogen with a mechanism to tightly control its adhesive function during colonization and infection.
Collapse
|
110
|
Vayne C, Nguyen TH, Rollin J, Charuel N, Poupon A, Pouplard C, Normann N, Gruel Y, Greinacher A. Characterization of New Monoclonal PF4-Specific Antibodies as Useful Tools for Studies on Typical and Autoimmune Heparin-Induced Thrombocytopenia. Thromb Haemost 2020; 121:322-331. [PMID: 33086397 DOI: 10.1055/s-0040-1717078] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Heparin-induced thrombocytopenia (HIT) is typically caused by platelet-activating immunoglobulin G (IgG) antibodies (Abs) against platelet factor 4 (PF4) complexed with heparin (H). Much less frequent "autoimmune" HIT is distinguished from typical HIT by platelet activation without heparin and the presence of both anti-PF4/H and anti-PF4 IgG. We developed three murine monoclonal anti-PF4 Abs with a human Fc-part, 1E12, 1C12, and 2E1, resembling autoimmune HIT Abs. OBJECTIVES To characterize 1E12, 1C12, and 2E1 in comparison to the heparin-dependent monoclonal anti-PF4/H Abs 5B9 and KKO, and polyclonal Abs from patients with typical HIT (group-2) and autoimmune HIT (group-3). METHODS Interactions of Abs with PF4 and PF4/H were studied by enzyme-linked-immunosorbent assay, single-molecule force spectroscopy, isothermal titration calorimetry, and dynamic light scattering. Serotonin release assay and heparin-induced platelet activation assay were used to assess platelet activation. The binding sites of monoclonal Abs on PF4 were predicted in silico (MAbTope method). RESULTS 1C12, 1E12, and 2E1 displayed higher affinity for PF4/H complexes than 5B9 and KKO, comparable to human group-3 Abs. Only 1C12, 1E12, 2E1, and group-3 Abs formed large complexes with native PF4, and activated platelets without heparin. The predicted binding sites of 1C12, 1E12, and 2E1 on PF4 differed from those of KKO and 5B9, but were close to each other. 2E1 exhibited unique bivalent binding, involving its antigen recognition site to PF4 and charge-dependent interactions with heparin. CONCLUSION 1C12, 1E12, and 2E1 are tools for studying the pathophysiology of autoimmune HIT. 2E1 provides evidence for a new binding mechanism of HIT Abs.
Collapse
Affiliation(s)
- Caroline Vayne
- EA7501 GICC, University of Tours, Tours, France.,Department of Haemostasis, Regional University Hospital Centre Tours, Tours, France
| | - Thi-Huong Nguyen
- Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, Greifswald, Germany.,Institute for Bioprocessing and Analytical Measurement Techniques, Heilbad Heiligenstadt, Germany
| | - Jérôme Rollin
- EA7501 GICC, University of Tours, Tours, France.,Department of Haemostasis, Regional University Hospital Centre Tours, Tours, France
| | | | - Anne Poupon
- PRC, INRA, CNRS, University of Tours, Nouzilly, France.,MAbSilico SAS, Nouzilly, France
| | - Claire Pouplard
- EA7501 GICC, University of Tours, Tours, France.,Department of Haemostasis, Regional University Hospital Centre Tours, Tours, France
| | - Nicole Normann
- Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, Greifswald, Germany
| | - Yves Gruel
- EA7501 GICC, University of Tours, Tours, France.,Department of Haemostasis, Regional University Hospital Centre Tours, Tours, France
| | - Andreas Greinacher
- Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, Greifswald, Germany
| |
Collapse
|
111
|
Wang H, Li H. Mechanically tightening, untying and retying a protein trefoil knot by single-molecule force spectroscopy. Chem Sci 2020; 11:12512-12521. [PMID: 34123232 PMCID: PMC8162576 DOI: 10.1039/d0sc02796k] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Knotted conformation is one of the most surprising topological features found in proteins, and understanding the folding mechanism of such knotted proteins remains a challenge. Here, we used optical tweezers (OT) to investigate the mechanical unfolding and folding behavior of a knotted protein Escherichia coli tRNA (guanosine-1) methyltransferase (TrmD). We found that when stretched from its N- and C-termini, TrmD can be mechanically unfolded and stretched into a tightened trefoil knot, which is composed of ca. 17 residues. Stretching of the unfolded TrmD involved a compaction process of the trefoil knot at low forces. The unfolding pathways of the TrmD were bifurcated, involving two-state and three-state pathways. Upon relaxation, the tightened trefoil knot loosened up first, leading to the expansion of the knot, and the unfolded TrmD can then fold back to its native state efficiently. By using an engineered truncation TrmD variant, we stretched TrmD along a pulling direction to allow us to mechanically unfold TrmD and untie the trefoil knot. We found that the folding of TrmD from its unfolded polypeptide without the knot is significantly slower. The knotting is the rate-limiting step of the folding of TrmD. Our results highlighted the critical importance of the knot conformation for the folding and stability of TrmD, offering a new perspective to understand the role of the trefoil knot in the biological function of TrmD. Optical tweezers are used to stretch a knotted protein along different directions to probe its unfolding–folding behaviors, and the conformational change of its knot structure. ![]()
Collapse
Affiliation(s)
- Han Wang
- Department of Chemistry, University of British Columbia Vancouver BC V6T 1Z1 Canada
| | - Hongbin Li
- Department of Chemistry, University of British Columbia Vancouver BC V6T 1Z1 Canada
| |
Collapse
|
112
|
Schäfer K, Diezemann G. Force-dependent folding pathways in mechanically interlocked calixarene dimers via atomistic force quench simulations. Mol Phys 2020. [DOI: 10.1080/00268976.2020.1743886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Ken Schäfer
- Institut für Physikalische Chemie, Universität Mainz, Mainz, Germany
| | - Gregor Diezemann
- Institut für Physikalische Chemie, Universität Mainz, Mainz, Germany
| |
Collapse
|
113
|
Cai PC, Krajina BA, Spakowitz AJ. Brachiation of a polymer chain in the presence of a dynamic network. Phys Rev E 2020; 102:020501. [PMID: 32942387 DOI: 10.1103/physreve.102.020501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 07/08/2020] [Indexed: 11/07/2022]
Abstract
The viscoelastic behavior of a physically crosslinked gel involves a spectrum of molecular relaxation processes, which at the single-chain level involve the chain undergoing transient hand-to-hand motion through the network. We develop a self-consistent theory for describing transiently associating polymer solutions that captures these complex dynamics. A single polymer chain transiently binds to a viscoelastic background that represents the polymer network formed by surrounding polymer chains. The viscoelastic background is described in the equation of motion as a memory kernel, which is self-consistently determined based on the predicted rheological behavior from the chain itself. The solution to the memory kernel is translated into rheological predictions of the complex modulus over a wide range of frequencies to capture the time-dependent behavior of a physical gel. Using the loss tangent predictions, a phase diagram is shown for the sol-gel transition of polymers with dynamic association affinities. This theory provides a predictive, molecular-level framework for the design of associating gels and supramolecular assemblies with targeted rheological properties.
Collapse
Affiliation(s)
- Pamela C Cai
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA
| | - Brad A Krajina
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA
| | - Andrew J Spakowitz
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA.,Department of Materials Science, Stanford University, Stanford, California 94305, USA.,Department of Applied Physics, Stanford University, Stanford, California 94305, USA.,Biophysics Program, Stanford University, Stanford, California 94305, USA
| |
Collapse
|
114
|
Daniel D, Florida Y, Lay CL, Koh XQ, Sng A, Tomczak N. Quantifying Surface Wetting Properties Using Droplet Probe Atomic Force Microscopy. ACS APPLIED MATERIALS & INTERFACES 2020; 12:42386-42392. [PMID: 32799518 DOI: 10.1021/acsami.0c12123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The functional properties of a surface, such as its anti-fogging or anti-fouling performance, are influenced by its wettability. To quantify surface wettability, the most common approach is to measure the contact angles of a liquid droplet on the surface. While well established and relatively easy to perform, contact angle measurements were developed to describe macroscopic wetting properties and are difficult to perform for submillimetric droplets. Moreover, they cannot spatially resolve surface heterogeneities that can contribute to surface fouling. To address these shortcomings, we report on using an atomic force microscopy technique to quantitatively measure the interaction forces between a microdroplet and a surface with piconewton force resolution. We show how our technique can be used to spatially map topographical and chemical heterogeneities with micron resolution.
Collapse
Affiliation(s)
- Dan Daniel
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, 138634 Singapore
| | - Yunita Florida
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, 138634 Singapore
| | - Chee Leng Lay
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, 138634 Singapore
| | - Xue Qi Koh
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, 138634 Singapore
| | - Anqi Sng
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, 138634 Singapore
| | - Nikodem Tomczak
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, 138634 Singapore
| |
Collapse
|
115
|
Xu XP, Pokutta S, Torres M, Swift MF, Hanein D, Volkmann N, Weis WI. Structural basis of αE-catenin-F-actin catch bond behavior. eLife 2020; 9:e60878. [PMID: 32915141 PMCID: PMC7588230 DOI: 10.7554/elife.60878] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 09/09/2020] [Indexed: 11/13/2022] Open
Abstract
Cell-cell and cell-matrix junctions transmit mechanical forces during tissue morphogenesis and homeostasis. α-Catenin links cell-cell adhesion complexes to the actin cytoskeleton, and mechanical load strengthens its binding to F-actin in a direction-sensitive manner. Specifically, optical trap experiments revealed that force promotes a transition between weak and strong actin-bound states. Here, we describe the cryo-electron microscopy structure of the F-actin-bound αE-catenin actin-binding domain, which in solution forms a five-helix bundle. In the actin-bound structure, the first helix of the bundle dissociates and the remaining four helices and connecting loops rearrange to form the interface with actin. Deletion of the first helix produces strong actin binding in the absence of force, suggesting that the actin-bound structure corresponds to the strong state. Our analysis explains how mechanical force applied to αE-catenin or its homolog vinculin favors the strongly bound state, and the dependence of catch bond strength on the direction of applied force.
Collapse
Affiliation(s)
| | - Sabine Pokutta
- Departments of Structural Biology and Molecular & Cellular Physiology, Stanford University School of MedicineStanfordUnited States
| | - Megan Torres
- Departments of Structural Biology and Molecular & Cellular Physiology, Stanford University School of MedicineStanfordUnited States
| | | | - Dorit Hanein
- Scintillon InstituteSan DiegoUnited States
- Department of Structural Biology and Chemistry, Pasteur InstituteParisFrance
| | - Niels Volkmann
- Scintillon InstituteSan DiegoUnited States
- Department of Structural Biology and Chemistry, Pasteur InstituteParisFrance
| | - William I Weis
- Departments of Structural Biology and Molecular & Cellular Physiology, Stanford University School of MedicineStanfordUnited States
| |
Collapse
|
116
|
Wang H, Shen B, Song Y, Lee M, Zhang W. Nanomechanical Properties of a Supramolecular Helix Stabilized by Non-Covalent Interactions. Macromol Rapid Commun 2020; 41:e2000453. [PMID: 32902027 DOI: 10.1002/marc.202000453] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 08/30/2020] [Indexed: 11/06/2022]
Abstract
Supramolecular helices have unique properties and many potential applications, such as chiral separation and asymmetric catalysis. Mechanical property (stability) of the supramolecular helix plays important roles in their functions. Due to the limitation of detection method, it is quite challenging to investigate nanomechanical properties of individual supramolecular helices stabilized by pure supramolecular interactions. Here atomic force microscopy (AFM)-based single molecule force spectroscopy (SMFS) is used to study the nanomechanical properties of a thermal-responsive supramolecular helix. The unwinding force plateau is observed in the force-extension curve, and the rupture force of the helix is dependent on the loading rate. In addition, the force-induced unwinding process is reversible and there is almost no energy dissipation in the process. Furthermore, the result of thermal shape-fluctuation analysis shows that the persistence length of the supramolecular helix is about 222 nm, which is much larger than helical structure formed by double-stranded DNA (dsDNA). However, because of its unique backbone structure, the supramolecular helix exhibits higher dynamic flexibility during force-induced deformation, since the persistence length determined from the stretching experiment is much smaller (1.1 nm).
Collapse
Affiliation(s)
- Huijie Wang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Bowen Shen
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Yu Song
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Myongsoo Lee
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Wenke Zhang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| |
Collapse
|
117
|
Directed manipulation of membrane proteins by fluorescent magnetic nanoparticles. Nat Commun 2020; 11:4259. [PMID: 32848156 PMCID: PMC7450064 DOI: 10.1038/s41467-020-18087-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 08/04/2020] [Indexed: 01/19/2023] Open
Abstract
The plasma membrane is the interface through which cells interact with their environment. Membrane proteins are embedded in the lipid bilayer of the plasma membrane and their function in this context is often linked to their specific location and dynamics within the membrane. However, few methods are available to manipulate membrane protein location at the single-molecule level. Here, we use fluorescent magnetic nanoparticles (FMNPs) to track membrane molecules and to control their movement. FMNPs allow single-particle tracking (SPT) at 10 nm and 5 ms spatiotemporal resolution, and using a magnetic needle, we pull membrane components laterally with femtonewton-range forces. In this way, we drag membrane proteins over the surface of living cells. Doing so, we detect barriers which we could localize to the submembrane actin cytoskeleton by super-resolution microscopy. We present here a versatile approach to probe membrane processes in live cells via the magnetic control of membrane protein motion. Membrane proteins are embedded in the lipid bilayer of the plasma membrane and their function in this context is often linked to their specific location and dynamics within the membrane. Here authors report the use of fluorescent magnetic nanoparticles to track membrane molecules and to manipulate their movement and pull membrane components laterally through the membrane with femtonewton-range forces.
Collapse
|
118
|
Kurus NN, Dultsev FN, Golyshev VM, Nekrasov DV, Pyshnyi DV, Lomzov AA. A QCM-based rupture event scanning technique as a simple and reliable approach to study the kinetics of DNA duplex dissociation. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2020; 12:3771-3777. [PMID: 32716423 DOI: 10.1039/d0ay00613k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Rupture Event Scanning (REVS) is applied for the first time within an approach based on dynamic force spectroscopy. Using model DNA duplexes containing 20 pairs of oligonucleotides including those containing single mismatches, we demonstrated the possibility of reliable determination of the kinetic parameters of dissociation of biomolecular complexes: barrier positions, the rate constants of dissociation, and the lifetime of complexes. Within this approach, mechanical dissociation of DNA duplexes occurs according to a mechanism similar to unzipping. It is shown that this process takes place by overcoming a single energy barrier. In the case where a mismatch is located at the farthest duplex end from the QCM surface, a substantial decrease in the position of the barrier between the bound and unbound states is observed. We suppose that this is due to the formation of an initiation complex containing 3-4 pairs of bases, and this is sufficient for starting duplex unzipping.
Collapse
Affiliation(s)
- N N Kurus
- Rzhanov Institute of Semiconductor Physics SB, RAS, 630090, Russia.
| | | | | | | | | | | |
Collapse
|
119
|
Qin J, Zhang M, Guan Y, Li C, Ma X, Rankl C, Tang J. Investigation of the interaction between MeCP2 methyl-CpG binding domain and methylated DNA by single molecule force spectroscopy. Anal Chim Acta 2020; 1124:52-59. [PMID: 32534675 DOI: 10.1016/j.aca.2020.05.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 05/07/2020] [Accepted: 05/11/2020] [Indexed: 11/19/2022]
Abstract
MeCP2 is an essential transcriptional repressor that mediates transcriptional inhibition by binding to methylated DNA. The binding specificity of MeCP2 protein to methylated DNA was considered to depend on its methyl-CpG binding domain (MBD). In this study, we used atomic force microscope based single-molecular force spectroscopy to investigate the interaction of MeCP2 MBD and methylated DNA. The specific interaction forces of the MeCP2 MBD-methylated DNA complexes were measured for the first time. The dynamics was also investigated by measuring the unbinding force of the complex at different loading rates. In addition, the distribution of unbinding forces and binding probabilities of MeCP2 MBD and different DNA were studied at the same loading rate. It was found that MeCP2 MBD had weak interaction with hemi-methylated and unmethylated DNA compared to methylated DNA. This work revealed the binding characteristics of MeCP2 MBD and methylated DNA at the single-molecule level. It provides a new idea for exploring the molecular mechanism of MeCP2 in regulating methylation signals.
Collapse
Affiliation(s)
- Juan Qin
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, PR China; University of Science and Technology of China, Hefei, 230026, PR China
| | - Miaomiao Zhang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, PR China; University of Science and Technology of China, Hefei, 230026, PR China
| | - Yanxue Guan
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, PR China; University of Science and Technology of China, Hefei, 230026, PR China
| | - Chen Li
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, PR China; University of Science and Technology of China, Hefei, 230026, PR China
| | - Xingxing Ma
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, PR China; University of Science and Technology of China, Hefei, 230026, PR China
| | - Christian Rankl
- RECENDT Research Center for Non Destructive Testing GmbH, Science Park 2/2.OG, Altenberger Straße 69, 4040 Linz, Austria
| | - Jilin Tang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, PR China; University of Science and Technology of China, Hefei, 230026, PR China.
| |
Collapse
|
120
|
Schiavone M, Sieczkowski N, Castex M, Trevisiol E, Dague E, François JM. AFM dendritips functionalized with molecular probes specific to cell wall polysaccharides as a tool to investigate cell surface structure and organization. Cell Surf 2020; 5:100027. [PMID: 32743143 PMCID: PMC7389267 DOI: 10.1016/j.tcsw.2019.100027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 05/13/2019] [Accepted: 06/14/2019] [Indexed: 12/13/2022] Open
Abstract
Functionalisation of AFM dendritips with conA, WGA and anti-β-1,3/β-1, 6-glucan antibodies. Cell wall polysaccharides were immobilized on epoxy-activated glass slides. Specific binding of immobilized polysaccharides to functionalized dendritips. Functionalized dendritips used as a new tool to probe yeast cell surface.
The yeast cell wall is composed of mannoproteins, β-1,3/β-1, 6-glucans and chitin. Each of these components has technological properties that are relevant for industrial and medical applications. To address issues related to cell wall structure and alteration in response to stress or conditioning processes, AFM dendritips were functionalized with biomolecules that are specific for each of the wall components, which was wheat germ agglutinin (WGA) for chitin, concanavalin A (ConA) for mannans and anti-β-1,3/anti-β-1,6-glucan antibodies for β-1,3/β-1,6-glucans. Binding specificity of these biomolecules were validated using penta-N-acetylchitopentaose, α-mannans, laminarin (short β-1,3-glucan chain) and gentiobiose (2 glucose units linked in β 1→6) immobilized on epoxy glass slides. Dynamic force spectroscopy was employed to obtain kinetic and thermodynamic information on the intermolecular interaction of the binary complexes using the model of Friddle-Noy-de Yoreo. Using this model, transition state distance xt, dissociate rate koff and the lowest force (feq) required to break the intermolecular bond of the complexes were approximated. These functionalized dendritips were then used to probe the yeast cell surface treated with a bacterial protease. As expected, this treatment, which removed the outer layer of the cell wall, gave accessibility to the inner layer composed of β-glucans. Likewise, bud scars were nicely localized using AFM dendritip bearing the WGA probe. To conclude, these functionalized AFM dendritips constitute a new toolbox that can be used to investigate cell surface structure and organization in response to a wide arrays of cultures and process conditions.
Collapse
Affiliation(s)
- Marion Schiavone
- LISBP, UMR INSA-CNRS 5504 & INRA 792, F-31077 Toulouse, France.,Lallemand SAS, 19, rue des briquetiers, 31702 Blagnac, France
| | | | - Mathieu Castex
- Lallemand SAS, 19, rue des briquetiers, 31702 Blagnac, France
| | | | - Etienne Dague
- CNRS, LAAS, 7 avenue du colonel Roche, F-31400 Toulouse, France
| | | |
Collapse
|
121
|
Protein mechanics probed using simple molecular models. Biochim Biophys Acta Gen Subj 2020; 1864:129613. [DOI: 10.1016/j.bbagen.2020.129613] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 03/06/2020] [Accepted: 04/08/2020] [Indexed: 01/14/2023]
|
122
|
Biomechanical Characterization of SARS-CoV-2 Spike RBD and Human ACE2 Protein-Protein Interaction. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2020. [PMID: 32766576 DOI: 10.1101/2020.07.31.230730] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The current COVID-19 pandemic has already had a devastating impact across the world. SARS-CoV-2 (the virus causing COVID-19) is known to use its surface spike (S) protein's receptor binding domain (RBD) to interact with the angiotensin-converting enzyme 2 (ACE2) receptor expressed on many human cell types. The RBD-ACE2 interaction is a crucial step to mediate the host cell entry of SARS-CoV-2. Recent studies indicate that the ACE2 interaction with the SARS-CoV-2 S protein has higher affinity than its binding with the structurally identical S protein of SARS-CoV-1, the virus causing the 2002-2004 SARS epidemic. However, the biophysical mechanism behind such binding affinity difference is unclear. This study utilizes a combined single-molecule force spectroscopy and steered molecular dynamics (SMD) simulation approach to quantify the specific interactions between CoV-2 or CoV-1 RBD and ACE2. Depending on the loading rates, the unbinding forces between CoV-2 RBD and ACE2 range from 70 to 110 pN, and are 30-50% higher than those of CoV-1 RBD and ACE2 under similar loading rates. SMD results indicate that CoV-2 RBD interacts with the N-linked glycan on Asn90 of ACE2. This interaction is mostly absent in the CoV-1 RBD-ACE2 complex. During the SMD simulations, the extra RBD-N-glycan interaction contributes to a greater force and prolonged interaction lifetime. The observation is confirmed by our experimental force spectroscopy study. After the removal of N-linked glycans on ACE2, its mechanical binding strength with CoV-2 RBD decreases to a similar level of the CoV-1 RBD-ACE2 interaction. Together, the study uncovers the mechanism behind the difference in ACE2 binding between SARS-CoV-2 and SARS-CoV-1, and could aid in the development of new strategies to block SARS-CoV-2 entry.
Collapse
|
123
|
Suma A, Coronel L, Bussi G, Micheletti C. Directional translocation resistance of Zika xrRNA. Nat Commun 2020; 11:3749. [PMID: 32719310 PMCID: PMC7385498 DOI: 10.1038/s41467-020-17508-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 06/29/2020] [Indexed: 12/14/2022] Open
Abstract
xrRNAs from flaviviruses survive in host cells because of their exceptional dichotomic response to the unfolding action of different enzymes. They can be unwound, and hence copied, by replicases, and yet can resist degradation by exonucleases. How the same stretch of xrRNA can encode such diverse responses is an open question. Here, by using atomistic models and translocation simulations, we uncover an elaborate and directional mechanism for how stress propagates when the two xrRNA ends, [Formula: see text] and [Formula: see text], are driven through a pore. Pulling the [Formula: see text] end, as done by replicases, elicits a progressive unfolding; pulling the [Formula: see text] end, as done by exonucleases, triggers a counterintuitive molecular tightening. Thus, in what appears to be a remarkable instance of intra-molecular tensegrity, the very pulling of the [Formula: see text] end is what boosts resistance to translocation and consequently to degradation. The uncovered mechanistic principle might be co-opted to design molecular meta-materials.
Collapse
Affiliation(s)
- Antonio Suma
- Dipartimento di Fisica, Università di Bari and INFN Sezione di Bari, via Amendola 173, 70126, Bari, Italy
- Institute for Computational Molecular Science (ICMS), Temple University, 19122, Philadelphia, PA, Italy
| | - Lucia Coronel
- Physics Area, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Via Bonomea 265, 34136, Trieste, Italy
| | - Giovanni Bussi
- Physics Area, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Via Bonomea 265, 34136, Trieste, Italy
| | - Cristian Micheletti
- Physics Area, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Via Bonomea 265, 34136, Trieste, Italy.
| |
Collapse
|
124
|
Deneke N, Rencheck ML, Davis CS. An engineer's introduction to mechanophores. SOFT MATTER 2020; 16:6230-6252. [PMID: 32567642 DOI: 10.1039/d0sm00465k] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Mechanophores (MPs) are a class of stimuli-responsive materials that are of increasing interest to engineers due to their potential applications as stress sensors. These mechanically responsive molecules change color or become fluorescent upon application of a mechanical stimulus as they undergo a chemical reaction when a load is applied. By incorporating MPs such as spirolactam, spiropyran, or dianthracene into a material system, the real-time stress distribution of the matrix can be directly observed through a visual response, ideal for damage and failure sensing applications. A wide array of applications that require continuous structural health monitoring could benefit from MPs including flexible electronics, protective coatings, and polymer matrix composites. However, there are significant technical challenges preventing MP implementation in industry. Effective strategies to quantitatively calibrate the photo response of the MP with applied stress magnitudes must be developed. Additionally, environmental conditions, including temperature, humidity, and ultraviolet light exposure can potentially impact the performance of MPs. By addressing these limitations, engineers can work to move MPs from the synthetic chemistry bench to the field. This review aims to highlight recent progress in MP research, discuss barriers to implementation, and provide an outlook on the future of MPs, specifically focused on polymeric material systems. Although the focus is on engineering MPs for bulk materials, a brief overview of mechanochemistry will be discussed followed by methods for activation and quantification of MP photo response (concentrating specifically on fluorescently active species). Finally, current challenges and future directions in MP research will be addressed.
Collapse
Affiliation(s)
- Naomi Deneke
- School of Materials Engineering, Purdue University, West Lafayette, Indiana 47906, USA.
| | - Mitchell L Rencheck
- School of Materials Engineering, Purdue University, West Lafayette, Indiana 47906, USA.
| | - Chelsea S Davis
- School of Materials Engineering, Purdue University, West Lafayette, Indiana 47906, USA.
| |
Collapse
|
125
|
The Molecular Complex between Staphylococcal Adhesin SpsD and Fibronectin Sustains Mechanical Forces in the Nanonewton Range. mBio 2020; 11:mBio.00371-20. [PMID: 32636242 PMCID: PMC7343985 DOI: 10.1128/mbio.00371-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The bacterial pathogen Staphylococcus pseudintermedius is involved in canine otitis externa and pyoderma as well as in surgical wound and urinary tract infections. Invasion of canine epithelial cells is promoted by S. pseudintermedius fibronectin (Fn)-binding proteins SpsD and SpsL through molecular interactions that are currently unknown. By means of single-molecule experiments, we discover that both adhesins have distinct molecular mechanisms for binding to Fn. We show that the SpsD-Fn interaction has a strength equivalent to that of a covalent bond (∼1.5 to 1.8 nN), which is an order of magnitude stronger than the binding force of classical receptor-ligand complexes. We suggest that this extreme mechanostability originates from the β-sheet organization of a tandem β-zipper. Upon binding to FnI modules, the intrinsically disordered binding sequences of SpsD would shift into an ordered structure by forming additional β-strands along triple peptide β-sheets in the Fn molecule. Dynamic force measurements reveal an unexpected behavior, i.e., that strong bonds are activated by mechanical tension as observed with catch bonds. By contrast, the SpsL-Fn interaction involves multiple weak bonds (∼0.2 nN) that rupture sequentially under force. Together with the recently described dock, lock, and latch complex, the ultrastrong interaction unraveled here is among the strongest noncovalent biological interaction measured to date. Our findings may find applications for the identification of inhibitory compounds to treat infections triggered by pathogens engaged in tandem β-zipper interactions.IMPORTANCE Binding of Staphylococcus pseudintermedius surface proteins SpsD and SpsL to fibronectin (Fn) plays a critical role in the invasion of canine epithelial cells. Here, we discover that both adhesins have different mechanisms for binding to Fn. The force required to separate SpsD from Fn is extremely strong, consistent with the unusual β-sheet organization of a high-affinity tandem β-zipper. By contrast, unbinding of the SpsL-Fn complex involves the sequential rupture of single weak bonds. Our findings may be of biological relevance as SpsD and SpsL are likely to play complementary roles during invasion. While the SpsD β-zipper supports strong bacterial adhesion and triggers invasion, the weak SpsL interaction would favor fast detachment, enabling the pathogen to colonize new sites.
Collapse
|
126
|
Chowdhury D, Ghanti D. Soft mechano-chemistry of molecular hubs in mitotic spindle: biomechanics and mechanical proofreading at microtubule ends. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:284001. [PMID: 32133984 DOI: 10.1088/1361-648x/ab7cc5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A microtubule (MT) is a long stiff tube-shaped filament formed by a hierarchical organization of a large number of tubulin protein molecules. These filaments constitute a major structural component of the scaffold of a multi-component macromolecular machine called mitotic spindle. The plus ends of the MTs are tethered to some specific binding partners by molecular tethers while those of some others are crosslinked by crosslinking molecules. Because of the non-covalent binding involved in the tethering and crosslinking, the attachments formed are intrinsically 'soft'. These attachments are transient because these can get ruptured spontaneously by thermal fluctuations. By implementing in silico the standard protocols of in vitro molecular force spectroscopy, we compute the lifetimes of simple theoretical models of these attachments. The mean lifetime is essentially a mean first-passage time. The stability of cross-linked antiparallel MTs is shown to decrease monotonically with increasing tension, a characteristic of all 'slip-bonds'. This is in sharp contrast to the nonmonotonic variation of the mean lifetime with tension, a mechanical fingerprint of 'catch-bonds', displayed by the MTs tethered to two distinct binding partners. We mention plausible functional implications of these observations in the context of mechanical proofreading.
Collapse
|
127
|
Angioletti-Uberti S. On the interpretation of kinetics and thermodynamics probed by single-molecule experiments. Colloid Polym Sci 2020. [DOI: 10.1007/s00396-020-04662-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AbstractSingle-molecule pulling experiments are widely used to extract both thermodynamic and kinetic data on ligand-receptor pairs, typically by fitting different models to the probability distribution of rupture forces of the corresponding bond. Here, a theoretical model is presented that shows how a measurement of the number of binding and unbinding events as a function of the observation time can also give access to both the binding (kon) and the unbinding (koff) rates of bonds, which combined provide a well-defined bond free-energy ΔGbond. The connection between ΔGbond and the ligand-receptor binding constant measured by typical binding essays is critically discussed. The role played by the molecular construct used to tether ligands and receptors to a surface is considered, highlighting the various approximations necessary to derive general expressions that connect its structure to its contribution, termed ΔGcnf, to the bond free-energy. In this way, the validity and the assumptions underpinning widely employed formulas and experimental protocols used to extract binding constants from single-molecule experiments are assessed. Finally, the role of ΔGcnf in processes mediated by ligand-receptor binding is briefly considered, and an experiment to unambiguously measure this quantity proposed.
Collapse
|
128
|
Llorente García I, Marsh M. A biophysical perspective on receptor-mediated virus entry with a focus on HIV. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2020; 1862:183158. [PMID: 31863725 PMCID: PMC7156917 DOI: 10.1016/j.bbamem.2019.183158] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 12/12/2019] [Accepted: 12/13/2019] [Indexed: 12/14/2022]
Abstract
As part of their entry and infection strategy, viruses interact with specific receptor molecules expressed on the surface of target cells. The efficiency and kinetics of the virus-receptor interactions required for a virus to productively infect a cell is determined by the biophysical properties of the receptors, which are in turn influenced by the receptors' plasma membrane (PM) environments. Currently, little is known about the biophysical properties of these receptor molecules or their engagement during virus binding and entry. Here we review virus-receptor interactions focusing on the human immunodeficiency virus type 1 (HIV), the etiological agent of acquired immunodeficiency syndrome (AIDS), as a model system. HIV is one of the best characterised enveloped viruses, with the identity, roles and structure of the key molecules required for infection well established. We review current knowledge of receptor-mediated HIV entry, addressing the properties of the HIV cell-surface receptors, the techniques used to measure these properties, and the macromolecular interactions and events required for virus entry. We discuss some of the key biophysical principles underlying receptor-mediated virus entry and attempt to interpret the available data in the context of biophysical mechanisms. We also highlight crucial outstanding questions and consider how new tools might be applied to advance understanding of the biophysical properties of viral receptors and the dynamic events leading to virus entry.
Collapse
Affiliation(s)
| | - Mark Marsh
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
| |
Collapse
|
129
|
Liu Y, Vancso GJ. Polymer single chain imaging, molecular forces, and nanoscale processes by Atomic Force Microscopy: The ultimate proof of the macromolecular hypothesis. Prog Polym Sci 2020. [DOI: 10.1016/j.progpolymsci.2020.101232] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
|
130
|
Lansakara TI, Morris HS, Singh P, Kohen A, Tivanski AV. Rigid Double-Stranded DNA Linkers for Single Molecule Enzyme-Drug Interaction Measurements Using Molecular Recognition Force Spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:4174-4183. [PMID: 32233509 DOI: 10.1021/acs.langmuir.9b03495] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Single-molecule studies can reveal the distribution of states and interactions between ligand-enzyme complexes not accessible for most studies that measure a large ensemble average response of many molecules. Furthermore, in some biological applications, the information regarding the outliers, not the average of measured properties, can be more important. The high spatial and force resolution provided by atomic force microscopy (AFM) under physiological conditions has been utilized in this study to quantify the force-distance relations of enzyme-drug interactions. Different immobilization techniques of the protein to a surface and the drug to AFM tip were quantitatively compared to improve the accuracy and precision of the measurement. Protein that is directly bound to the surface, forming a monolayer, was compared to enzyme molecules bound to the surface with rigid double-stranded (ds) DNA spacers. These surfaces immobilization techniques were studied with the drug bound directly to the AFM tip and drug bound via flexible poly(ethylene glycol) and rigid dsDNA linkers. The activity of the enzyme was found to be not significantly altered by immobilization methods relative to its activity in solution. The findings indicate that the approach for studying drug-enzyme interaction based on rigid dsDNA linker on the surface and either flexible or rigid linker on the tip affords straightforward, highly specific, reproducible, and accurate force measurements with a potential for single-molecule level studies. The method could facilitate in-depth examination of a broad spectrum of biological targets and potential drugs.
Collapse
Affiliation(s)
| | - Holly S Morris
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Priyanka Singh
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Amnon Kohen
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Alexei V Tivanski
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| |
Collapse
|
131
|
Mechanical Energy before Chemical Energy at the Origins of Life? SCI 2020. [DOI: 10.3390/sci2020019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Mechanical forces and mechanical energy are prevalent in living cells. This may be because mechanical forces and mechanical energy preceded chemical energy at life’s origins. Mechanical energy is more readily available in non-living systems than the various forms of chemical energy used by living systems. Two possible prebiotic environments that might have provided mechanical energy are hot pools that experience wet/dry cycles and mica sheets as they move, open and shut, as heat pumps or in response to water movements.
Collapse
|
132
|
Imaging and Force Spectroscopy of Single Transmembrane Proteins with the Atomic Force Microscope. Methods Mol Biol 2020. [PMID: 31218616 DOI: 10.1007/978-1-4939-9512-7_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
The atomic force microscope (AFM) has opened avenues and provided opportunities to investigate biological soft matter and processes ranging from nanometer (nm) to millimeter (mm). The high temporal (millisecond) and spatial (nanometer) resolutions of the AFM are suited for studying many biological processes in their native conditions. The AFM cantilever-aptly termed as a "lab on a tip"-can be used as an imaging tool as well as a handle to manipulate single bonds and proteins. Recent examples have convincingly established AFM as a tool to study the mechanical properties and monitor processes of single proteins and cells with high sensitivity, thus affording insight into important mechanistic details. This chapter specifically focuses on practical and analytical protocols of single-molecule AFM methodologies related to high-resolution imaging and single-molecule force spectroscopy of transmembrane proteins in a lipid bilayer (reconstituted or native). Both these techniques are operator oriented, and require specialized working knowledge of the instrument, theory and practical skills.
Collapse
|
133
|
Landuzzi F, Viader-Godoy X, Cleri F, Pastor I, Ritort F. Detection of single DNA mismatches by force spectroscopy in short DNA hairpins. J Chem Phys 2020; 152:074204. [PMID: 32087630 DOI: 10.1063/1.5139284] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Identification of defective DNA structures is a difficult task, since small differences in base-pair bonding are hidden in the local structural variability of a generally random base-pair sequence. Defects, such as base mismatches, missing bases, crosslinks, and so on, occur in DNA with high frequency and must be efficiently identified and repaired to avoid dire consequences such as genetic mutations. Here, we focus on the detection of base mismatches, which is local deviations from the ideal Watson-Crick pairing rule, which may typically originate from DNA replication process, foreign chemical attack, or ionizing radiation. Experimental detection of a mismatch defect demands the ability to measure slight deviations in the free energy and molecular structure. We introduce different mismatches in short DNA hairpins (10 or 20 base pairs plus a 4-base loop) sandwiched between dsDNA handles to be used in single-molecule force spectroscopy with optical tweezers. We perform both hopping and force-pulling experiments to measure the excess free energies and deduce the characteristic kinetic signatures of the mismatch from the force-distance curves. All-atom molecular dynamics simulations lend support to the detailed interpretation of the experimental data. Such measurements, at the lowest sensitivity limits of this experimental technique, demonstrate the capability of identifying the presence of mismatches in a random complementary dsDNA sequence and provide lower bounds for the ability to distinguish different structural defects.
Collapse
Affiliation(s)
- F Landuzzi
- Department of Physics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, Japan
| | - X Viader-Godoy
- Small Biosystems Lab., Univ. de Barcelona, Diagonal 647, 08028 Barcelona, Spain
| | - F Cleri
- I.E.M.N. (UMR Cnrs 8520), 59652 Villeneuve d'Ascq, France
| | - I Pastor
- Small Biosystems Lab., Univ. de Barcelona, Diagonal 647, 08028 Barcelona, Spain
| | - F Ritort
- Small Biosystems Lab., Univ. de Barcelona, Diagonal 647, 08028 Barcelona, Spain
| |
Collapse
|
134
|
Kluger C, Braun L, Sedlak SM, Pippig DA, Bauer MS, Miller K, Milles LF, Gaub HE, Vogel V. Different Vinculin Binding Sites Use the Same Mechanism to Regulate Directional Force Transduction. Biophys J 2020; 118:1344-1356. [PMID: 32109366 PMCID: PMC7091509 DOI: 10.1016/j.bpj.2019.12.042] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 12/17/2019] [Accepted: 12/30/2019] [Indexed: 12/18/2022] Open
Abstract
Vinculin is a universal adaptor protein that transiently reinforces the mechanical stability of adhesion complexes. It stabilizes mechanical connections that cells establish between the actomyosin cytoskeleton and the extracellular matrix via integrins or to neighboring cells via cadherins, yet little is known regarding its mechanical design. Vinculin binding sites (VBSs) from different nonhomologous actin-binding proteins use conserved helical motifs to associate with the vinculin head domain. We studied the mechanical stability of such complexes by pulling VBS peptides derived from talin, α-actinin, and Shigella IpaA out of the vinculin head domain. Experimental data from atomic force microscopy single-molecule force spectroscopy and steered molecular dynamics (SMD) simulations both revealed greater mechanical stability of the complex for shear-like than for zipper-like pulling configurations. This suggests that reinforcement occurs along preferential force directions, thus stabilizing those cytoskeletal filament architectures that result in shear-like pulling geometries. Large force-induced conformational changes in the vinculin head domain, as well as protein-specific fine-tuning of the VBS sequence, including sequence inversion, allow for an even more nuanced force response.
Collapse
Affiliation(s)
- Carleen Kluger
- Lehrstuhl für Angewandte Physik and Center for NanoScience, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Lukas Braun
- Laboratory of Applied Mechanobiology, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
| | - Steffen M Sedlak
- Lehrstuhl für Angewandte Physik and Center for NanoScience, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Diana A Pippig
- Lehrstuhl für Angewandte Physik and Center for NanoScience, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Magnus S Bauer
- Lehrstuhl für Angewandte Physik and Center for NanoScience, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Ken Miller
- Lehrstuhl für Angewandte Physik and Center for NanoScience, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Lukas F Milles
- Lehrstuhl für Angewandte Physik and Center for NanoScience, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Hermann E Gaub
- Lehrstuhl für Angewandte Physik and Center for NanoScience, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Viola Vogel
- Laboratory of Applied Mechanobiology, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland.
| |
Collapse
|
135
|
Stratigaki M, Göstl R. Methods for Exerting and Sensing Force in Polymer Materials Using Mechanophores. Chempluschem 2020; 85:1095-1103. [PMID: 31958366 DOI: 10.1002/cplu.201900737] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 01/17/2020] [Indexed: 11/08/2022]
Abstract
In recent years, polymer mechanochemistry has evolved as a methodology to provide insights into the action-reaction relationships of polymers and polymer-based materials and composites in terms of macroscopic force application (stress) and subsequent deformation (strain) through a mechanophore-assisted coupling of mechanical and chemical phenomena. The perplexity of the process, however, from the viewpoint of mechanophore activation via a molecular-scaled disruption of the structure that yields a macroscopically detectable optical signal, renders this otherwise rapidly evolving field challenging. Motivated by this, we highlight here recent advancements of polymer mechanochemistry with particular focus on the establishment of methodologies for the efficient activation and quantification of mechanophores and anticipate to aptly pinpoint unresolved matters and limitations of the respective approaches, thus highlighting possible developments.
Collapse
Affiliation(s)
- Maria Stratigaki
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056, Aachen, Germany
| | - Robert Göstl
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056, Aachen, Germany
| |
Collapse
|
136
|
Abstract
Mechanical forces and mechanical energy are prevalent in living cells. This may be because mechanical forces and mechanical energy preceded chemical energy at life’s origins. Mechanical energy is more readily available in non-living systems than the various forms of chemical energy used by living systems. Two possible prebiotic environments that might have provided mechanical energy are hot pools that experience wet/dry cycles and mica sheets as they move, open and shut, as heat pumps or in response to water movements.
Collapse
|
137
|
Hasegawa Y, Harashima T, Jono Y, Seki T, Kiguchi M, Nishino T. Kinetic investigation of a chemical process in single-molecule junction. Chem Commun (Camb) 2020; 56:309-312. [DOI: 10.1039/c9cc08383a] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Herein, we report on the kinetic investigation for the breakdown of single-molecule junctions.
Collapse
Affiliation(s)
- Yusuke Hasegawa
- Department of Chemistry
- School of Science
- Tokyo Institute of Technology
- Tokyo 152-8551
- Japan
| | - Takanori Harashima
- Department of Chemistry
- School of Science
- Tokyo Institute of Technology
- Tokyo 152-8551
- Japan
| | - Yuki Jono
- Department of Chemistry
- School of Science
- Tokyo Institute of Technology
- Tokyo 152-8551
- Japan
| | - Takumi Seki
- Department of Chemistry
- School of Science
- Tokyo Institute of Technology
- Tokyo 152-8551
- Japan
| | - Manabu Kiguchi
- Department of Chemistry
- School of Science
- Tokyo Institute of Technology
- Tokyo 152-8551
- Japan
| | - Tomoaki Nishino
- Department of Chemistry
- School of Science
- Tokyo Institute of Technology
- Tokyo 152-8551
- Japan
| |
Collapse
|
138
|
Wang H, Gao X, Li H. Single Molecule Force Spectroscopy Reveals the Mechanical Design Governing the Efficient Translocation of the Bacterial Toxin Protein RTX. J Am Chem Soc 2019; 141:20498-20506. [DOI: 10.1021/jacs.9b11281] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Han Wang
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Xiaoqing Gao
- State Key Laboratory of Precision Measuring Technology and Instruments School of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin, 300072, P. R. China
| | - Hongbin Li
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| |
Collapse
|
139
|
Estimation of Forces on Actin Filaments in Living Muscle from X-ray Diffraction Patterns and Mechanical Data. Int J Mol Sci 2019; 20:ijms20236044. [PMID: 31801239 PMCID: PMC6928692 DOI: 10.3390/ijms20236044] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2019] [Revised: 11/12/2019] [Accepted: 11/26/2019] [Indexed: 11/17/2022] Open
Abstract
Many biological processes are triggered or driven by mechanical forces in the cytoskeletal network, but these transducing forces have rarely been assessed. Striated muscle, with its well-organized structure provides an opportunity to assess intracellular forces using small-angle X-ray fiber diffraction. We present a new methodology using Monte Carlo simulations of muscle contraction in an explicit 3D sarcomere lattice to predict the fiber deformations and length changes along thin filaments during contraction. Comparison of predicted diffraction patterns to experimental meridional X-ray reflection profiles allows assessment of the stepwise changes in intermonomer spacings and forces in the myofilaments within living muscle cells. These changes along the filament length reflect the effect of forces from randomly attached crossbridges. This approach enables correlation of the molecular events, such as the current number of attached crossbridges and the distributions of crossbridge forces to macroscopic measurements of force and length changes during muscle contraction. In addition, assessments of fluctuations in local forces in the myofilaments may reveal how variations in the filament forces acting on signaling proteins in the sarcomere M-bands and Z-discs modulate gene expression, protein synthesis and degradation, and as well to mechanisms of adaptation of muscle in response to changes in mechanical loading.
Collapse
|
140
|
Lim YB, Thingna J, Kong F, Dao M, Cao J, Lim CT. Temperature-Induced Catch-Slip to Slip Bond Transit in Plasmodium falciparum-Infected Erythrocytes. Biophys J 2019; 118:105-116. [PMID: 31813540 DOI: 10.1016/j.bpj.2019.11.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 10/26/2019] [Accepted: 11/12/2019] [Indexed: 11/28/2022] Open
Abstract
Plasmodium falciparum malaria-infected red blood cells (IRBCs), or erythrocytes, avoid splenic clearance by adhering to host endothelium. Upregulation of endothelial receptors intercellular adhesion molecule-1 (ICAM-1) and cluster of differentiation 36 (CD36) are associated with severe disease pathology. Most in vitro studies of IRBCs interacting with these molecules were conducted at room temperature. However, as IRBCs are exposed to temperature variations between 37°C (body temperature) and 41°C (febrile temperature) in the host, it is important to understand IRBC-receptor interactions at these physiologically relevant temperatures. Here, we probe IRBC interactions against ICAM-1 and CD36 at 37 and 41°C. Single bond force-clamp spectroscopy is used to determine the bond dissociation rates and hence, unravel the nature of the IRBC-receptor interaction. The association rates are also extracted from a multiple bond flow assay using a cellular stochastic model. Surprisingly, IRBC-ICAM-1 bond transits from a catch-slip bond at 37°C toward a slip bond at 41°C. Moreover, binding affinities of both IRBC-ICAM-1 and IRBC-CD36 decrease as the temperature rises from 37 to 41°C. This study highlights the significance of examining receptor-ligand interactions at physiologically relevant temperatures and reveals biophysical insight into the temperature dependence of P. falciparum malaria cytoadherent bonds.
Collapse
Affiliation(s)
- Ying Bena Lim
- Department of Biomedical Engineering, National University of Singapore, Singapore; Singapore-Massachusetts Institute of Technology Alliance for Research and Technology Centre, Infectious Diseases IRG, Singapore
| | - Juzar Thingna
- Singapore-Massachusetts Institute of Technology Alliance for Research and Technology Centre, Infectious Diseases IRG, Singapore; Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts; Center for Theoretical Physics of Complex Systems, Institute for Basic Science, Daejeon, Republic of Korea
| | - Fang Kong
- Singapore-Massachusetts Institute of Technology Alliance for Research and Technology Centre, Infectious Diseases IRG, Singapore; School of Biological Science, Nanyang Technological University, Singapore
| | - Ming Dao
- Singapore-Massachusetts Institute of Technology Alliance for Research and Technology Centre, Infectious Diseases IRG, Singapore; School of Biological Science, Nanyang Technological University, Singapore; Department of Material Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Jianshu Cao
- Singapore-Massachusetts Institute of Technology Alliance for Research and Technology Centre, Infectious Diseases IRG, Singapore; Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts.
| | - Chwee Teck Lim
- Department of Biomedical Engineering, National University of Singapore, Singapore; Singapore-Massachusetts Institute of Technology Alliance for Research and Technology Centre, Infectious Diseases IRG, Singapore; Institute for Health Innovation and Technology (iHealthtech), National University of Singapore, Singapore.
| |
Collapse
|
141
|
Galvez-Martinez S, Escamilla-Roa E, Zorzano MP, Mateo-Marti E. Defects on a pyrite(100) surface produce chemical evolution of glycine under inert conditions: experimental and theoretical approaches. Phys Chem Chem Phys 2019; 21:24535-24542. [PMID: 31663552 DOI: 10.1039/c9cp03577j] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The presence of non-stoichiometric sites on the pyrite(100) surface makes it a suitable substrate for driving the chemical evolution of the amino acid glycine over time, even under inert conditions. Spectroscopic molecular fingerprints prove a transition process from a zwitterionic species to an anionic species over time on the monosulfide enriched surface. By combining experimental and theoretical approaches, we propose a surface mechanism where the interaction between the amino acid species and the surface will be driven by the quenching of the surface states at Fe sites and favoured by sulfur vacancies. This study demonstrates the potential capability of pyrite to act as a surface catalyst.
Collapse
Affiliation(s)
- Santos Galvez-Martinez
- Centro de Astrobiología (CSIC-INTA), Ctra. Ajalvir, Km. 4, 28850 Torrejón de Ardoz, Madrid, Spain.
| | | | | | | |
Collapse
|
142
|
Pohl A, Berger F, Sullan RMA, Valverde-Tercedor C, Freindl K, Spiridis N, Lefèvre CT, Menguy N, Klumpp S, Blank KG, Faivre D. Decoding Biomineralization: Interaction of a Mad10-Derived Peptide with Magnetite Thin Films. NANO LETTERS 2019; 19:8207-8215. [PMID: 31565946 DOI: 10.1021/acs.nanolett.9b03560] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Protein-surface interactions play a pivotal role in processes as diverse as biomineralization, biofouling, and the cellular response to medical implants. In biomineralization processes, biomacromolecules control mineral deposition and architecture via complex and often unknown mechanisms. For studying these mechanisms, the formation of magnetite nanoparticles in magnetotactic bacteria has become an excellent model system. Most interestingly, nanoparticle morphologies have been discovered that defy crystallographic rules (e.g., in the species Desulfamplus magnetovallimortis strain BW-1). In certain conditions, this strain mineralizes bullet-shaped magnetite nanoparticles, which exhibit defined (111) crystal faces and are elongated along the [100] direction. We hypothesize that surface-specific protein interactions break the nanoparticle symmetry, inhibiting the growth of certain crystal faces and thereby favoring the growth of others. Screening the genome of BW-1, we identified Mad10 (Magnetosome-associated deep-branching) as a potential magnetite-binding protein. Using atomic force microscope (AFM)-based single-molecule force spectroscopy, we show that a Mad10-derived peptide, which represents the most conserved region of Mad10, binds strongly to (100)- and (111)-oriented single-crystalline magnetite thin films. The peptide-magnetite interaction is thus material- but not crystal-face-specific. It is characterized by broad rupture force distributions that do not depend on the retraction speed of the AFM cantilever. To account for these experimental findings, we introduce a three-state model that incorporates fast rebinding. The model suggests that the peptide-surface interaction is strong in the absence of load, which is a direct result of this fast rebinding process. Overall, our study sheds light on the kinetic nature of peptide-surface interactions and introduces a new magnetite-binding peptide with potential use as a functional coating for magnetite nanoparticles in biotechnological and biomedical applications.
Collapse
Affiliation(s)
- Anna Pohl
- Department of Biomaterials , Max Planck Institute of Colloids and Interfaces , Am Mühlenberg 1 , 14476 Potsdam , Germany
- Mechano(bio)chemistry , Max Planck Institute of Colloids and Interfaces , Am Mühlenberg 1 , 14476 Potsdam , Germany
| | - Florian Berger
- Laboratory of Sensory Neuroscience , The Rockefeller University , 1230 York Avenue , New York 10065 , United States
| | - Ruby M A Sullan
- Mechano(bio)chemistry , Max Planck Institute of Colloids and Interfaces , Am Mühlenberg 1 , 14476 Potsdam , Germany
| | - Carmen Valverde-Tercedor
- Department of Biomaterials , Max Planck Institute of Colloids and Interfaces , Am Mühlenberg 1 , 14476 Potsdam , Germany
| | - Kinga Freindl
- Jerzy Haber Institute of Catalysis and Surface Chemistry , Polish Academy of Sciences , Niezapominajek 8 , 30-239 Krakow , Poland
| | - Nika Spiridis
- Jerzy Haber Institute of Catalysis and Surface Chemistry , Polish Academy of Sciences , Niezapominajek 8 , 30-239 Krakow , Poland
| | | | - Nicolas Menguy
- Sorbonne Université , UMR CNRS 7590, IRD. MNHN, Institut de Minéralogie, Physique des Matériaux et Cosmochimie - IMPMC , 4 Place Jussieu , 75005 Paris , France
| | - Stefan Klumpp
- Department of Theory & Bio-Systems , Max Planck Institute of Colloids and Interfaces , Am Mühlenberg 1 , 14476 Potsdam , Germany
- Institute for the Dynamics of Complex Systems , University of Göttingen , Friedrich Hund Platz 1 , 37077 Göttingen , Germany
| | - Kerstin G Blank
- Mechano(bio)chemistry , Max Planck Institute of Colloids and Interfaces , Am Mühlenberg 1 , 14476 Potsdam , Germany
| | - Damien Faivre
- Department of Biomaterials , Max Planck Institute of Colloids and Interfaces , Am Mühlenberg 1 , 14476 Potsdam , Germany
- Aix-Marseille Université , CEA, CNRS, BIAM, 13108 Saint Paul lez Durance , France
| |
Collapse
|
143
|
Kostrz D, Wayment-Steele HK, Wang JL, Follenfant M, Pande VS, Strick TR, Gosse C. A modular DNA scaffold to study protein-protein interactions at single-molecule resolution. NATURE NANOTECHNOLOGY 2019; 14:988-993. [PMID: 31548690 DOI: 10.1038/s41565-019-0542-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Accepted: 08/06/2019] [Indexed: 06/10/2023]
Abstract
The residence time of a drug on its target has been suggested as a more pertinent metric of therapeutic efficacy than the traditionally used affinity constant. Here, we introduce junctured-DNA tweezers as a generic platform that enables real-time observation, at the single-molecule level, of biomolecular interactions. This tool corresponds to a double-strand DNA scaffold that can be nanomanipulated and on which proteins of interest can be engrafted thanks to widely used genetic tagging strategies. Thus, junctured-DNA tweezers allow a straightforward and robust access to single-molecule force spectroscopy in drug discovery, and more generally in biophysics. Proof-of-principle experiments are provided for the rapamycin-mediated association between FKBP12 and FRB, a system relevant in both medicine and chemical biology. Individual interactions were monitored under a range of applied forces and temperatures, yielding after analysis the characteristic features of the energy profile along the dissociation landscape.
Collapse
Affiliation(s)
- Dorota Kostrz
- Ecole Normale Supérieure, Institut de Biologie de l'Ecole Normale Supérieure (IBENS) CNRS, INSERM, PSL Research University, Paris, France
- Laboratoire de Photonique et de Nanostructures, LPN-CNRS, Marcoussis, France
| | | | - Jing L Wang
- Institut Jacques Monod, CNRS, Université Paris Diderot, Université de Paris, Paris, France
| | - Maryne Follenfant
- Ecole Normale Supérieure, Institut de Biologie de l'Ecole Normale Supérieure (IBENS) CNRS, INSERM, PSL Research University, Paris, France
| | - Vijay S Pande
- Department of Bioengineering, Stanford University, Stanford, USA
| | - Terence R Strick
- Ecole Normale Supérieure, Institut de Biologie de l'Ecole Normale Supérieure (IBENS) CNRS, INSERM, PSL Research University, Paris, France.
- Institut Jacques Monod, CNRS, Université Paris Diderot, Université de Paris, Paris, France.
- Programme Equipe Labellisée, Ligue Nationale Contre le Cancer, Paris, France.
| | - Charlie Gosse
- Ecole Normale Supérieure, Institut de Biologie de l'Ecole Normale Supérieure (IBENS) CNRS, INSERM, PSL Research University, Paris, France.
- Laboratoire de Photonique et de Nanostructures, LPN-CNRS, Marcoussis, France.
| |
Collapse
|
144
|
Ma X, Gosai A, Shrotriya P. Resolving electrical stimulus triggered molecular binding and force modulation upon thrombin-aptamer biointerface. J Colloid Interface Sci 2019; 559:1-12. [PMID: 31605780 DOI: 10.1016/j.jcis.2019.09.080] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 08/28/2019] [Accepted: 09/21/2019] [Indexed: 11/15/2022]
Abstract
Experimental and computational approaches are utilized to investigate the influence of electrostatic fields on the binding force between human coagulation protein thrombin and its DNA aptamer. The thiolated aptamer was deposited onto gold substrate located in a liquid cell filled with binding buffer, then the thrombin-functionalized atomic force microscopy (AFM) probe was repeatedly brought into contact with the aptamer-coated surface under applied electrical potentials of -100, 0, and 100 mV respectively. Force drops during the pull-off process were measured to determine the unbinding forces between thrombin and aptamer in a range of loading rates spanning from ~3 × 102 to ~1 × 104 pN/s. The results from experiments showed that both of the binding strength and propensity of the complex are drastically diminished under positive electrode potential, whereas there is no influence on the molecular binding from negative electrode potential. We also used a theoretical analysis to explain the nature of electrostatic potential and field inside the aptamer-thrombin layer, which in turn could quantify the influence of the electrostatically repulsive force on a thrombin molecule that promotes dissociation from the aptamer due to positive electrode potential, and achieve good agreement with the experimental results. The study confirms the feasibility of electrostatic modulation upon the binding interaction between thrombin and aptamer, and implicates an underlying application perspective upon nanoscale manipulation of the stimuli responsive biointerface.
Collapse
Affiliation(s)
- Xiao Ma
- Department of Mechanical Engineering, Iowa State University, Ames, IA 50011, USA; Department of Biomedical Engineering, New York University, Brooklyn, NY 11201, USA.
| | - Agnivo Gosai
- Department of Mechanical Engineering, Iowa State University, Ames, IA 50011, USA
| | - Pranav Shrotriya
- Department of Mechanical Engineering, Iowa State University, Ames, IA 50011, USA.
| |
Collapse
|
145
|
Wang Z, Jumper JM, Freed KF, Sosnick TR. On the Interpretation of Force-Induced Unfolding Studies of Membrane Proteins Using Fast Simulations. Biophys J 2019; 117:1429-1441. [PMID: 31587831 DOI: 10.1016/j.bpj.2019.09.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Revised: 08/25/2019] [Accepted: 09/12/2019] [Indexed: 11/25/2022] Open
Abstract
Single-molecule force spectroscopy has proven extremely beneficial in elucidating folding pathways for membrane proteins. Here, we simulate these measurements, conducting hundreds of unfolding trajectories using our fast Upside algorithm for slow enough speeds to reproduce key experimental features that may be missed using all-atom methods. The speed also enables us to determine the logarithmic dependence of pulling velocities on the rupture levels to better compare to experimental values. For simulations of atomic force microscope measurements in which force is applied vertically to the C-terminus of bacteriorhodopsin, we reproduce the major experimental features including even the back-and-forth unfolding of single helical turns. When pulling laterally on GlpG to mimic the experiment, we observe quite different behavior depending on the stiffness of the spring. With a soft spring, as used in the experimental studies with magnetic tweezers, the force remains nearly constant after the initial unfolding event, and a few pathways and a high degree of cooperativity are observed in both the experiment and simulation. With a stiff spring, however, the force drops to near zero after each major unfolding event, and numerous intermediates are observed along a wide variety of pathways. Hence, the mode of force application significantly alters the perception of the folding landscape, including the number of intermediates and the degree of folding cooperativity, important issues that should be considered when designing experiments and interpreting unfolding data.
Collapse
Affiliation(s)
- Zongan Wang
- Department of Chemistry, James Franck Institute, The University of Chicago, Chicago, Illinois; Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois
| | - John M Jumper
- Department of Chemistry, James Franck Institute, The University of Chicago, Chicago, Illinois; Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois
| | - Karl F Freed
- Department of Chemistry, James Franck Institute, The University of Chicago, Chicago, Illinois.
| | - Tobin R Sosnick
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois; Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois.
| |
Collapse
|
146
|
Ouyang W, Ramakrishna SN, Rossi A, Urbakh M, Spencer ND, Arcifa A. Load and Velocity Dependence of Friction Mediated by Dynamics of Interfacial Contacts. PHYSICAL REVIEW LETTERS 2019; 123:116102. [PMID: 31573261 DOI: 10.1103/physrevlett.123.116102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Revised: 06/19/2019] [Indexed: 06/10/2023]
Abstract
Studying the frictional properties of interfaces with dynamic chemical bonds advances understanding of the mechanism underlying rate and state laws, and offers new pathways for the rational control of frictional response. In this work, we revisit the load dependence of interfacial chemical-bond-induced (ICBI) friction experimentally and find that the velocity dependence of friction can be reversed by changing the normal load. We propose a theoretical model, whose analytical solution allows us to interpret the experimental data on timescales and length scales that are relevant to experimental conditions. Our work provides a promising avenue for exploring the dynamics of ICBI friction.
Collapse
Affiliation(s)
- Wengen Ouyang
- School of Chemistry and The Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 69978, Israel
| | - Shivaprakash N Ramakrishna
- Laboratory for Surface Science and Technology, Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 5,CH-8093 Zurich, Switzerland
| | - Antonella Rossi
- Laboratory for Surface Science and Technology, Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 5,CH-8093 Zurich, Switzerland
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, Cittadella Universitaria di Monserrato, I-09100 Cagliari, Italy
| | - Michael Urbakh
- School of Chemistry and The Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 69978, Israel
| | - Nicholas D Spencer
- Laboratory for Surface Science and Technology, Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 5,CH-8093 Zurich, Switzerland
| | - Andrea Arcifa
- Laboratory for Surface Science and Technology, Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 5,CH-8093 Zurich, Switzerland
| |
Collapse
|
147
|
Li D, Ji B. Protein conformational transitions coupling with ligand interactions: Simulations from molecules to medicine. MEDICINE IN NOVEL TECHNOLOGY AND DEVICES 2019. [DOI: 10.1016/j.medntd.2019.100026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
|
148
|
Broken force dispersal network in tip-links by the mutations at the Ca 2+-binding residues induces hearing-loss. Biochem J 2019; 476:2411-2425. [PMID: 31399498 PMCID: PMC6717114 DOI: 10.1042/bcj20190453] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 08/07/2019] [Accepted: 08/09/2019] [Indexed: 12/26/2022]
Abstract
Tip-link as force-sensor in hearing conveys the mechanical force originating from sound to ion-channels while maintaining the integrity of the entire sensory assembly in the inner ear. This delicate balance between structure and function of tip-links is regulated by Ca2+-ions present in endolymph. Mutations at the Ca2+-binding sites of tip-links often lead to congenital deafness, sometimes syndromic defects impairing vision along with hearing. Although such mutations are already identified, it is still not clear how the mutants alter the structure-function properties of the force-sensors associated with diseases. With an aim to decipher the differences in force-conveying properties of the force-sensors in molecular details, we identified the conformational variability of mutant and wild-type tip-links at the single-molecule level using FRET at the endolymphatic Ca2+ concentrations and subsequently measured the force-responsive behavior using single-molecule force spectroscopy with an Atomic Force Microscope (AFM). AFM allowed us to mimic the high and wide range of force ramps (103-106 pN s-1) as experienced in the inner ear. We performed in silico network analysis to learn that alterations in the conformations of the mutants interrupt the natural force-propagation paths through the sensors and make the mutant tip-links vulnerable to input forces from sound stimuli. We also demonstrated that a Ca2+ rich environment can restore the force-response of the mutant tip-links which may eventually facilitate the designing of better therapeutic strategies to the hearing loss.
Collapse
|
149
|
McCauley MJ, Huo R, Becker N, Holte MN, Muthurajan UM, Rouzina I, Luger K, Maher LJ, Israeloff NE, Williams MC. Single and double box HMGB proteins differentially destabilize nucleosomes. Nucleic Acids Res 2019; 47:666-678. [PMID: 30445475 PMCID: PMC6344895 DOI: 10.1093/nar/gky1119] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 10/23/2018] [Indexed: 01/21/2023] Open
Abstract
Nucleosome disruption plays a key role in many nuclear processes including transcription, DNA repair and recombination. Here we combine atomic force microscopy (AFM) and optical tweezers (OT) experiments to show that high mobility group B (HMGB) proteins strongly disrupt nucleosomes, revealing a new mechanism for regulation of chromatin accessibility. We find that both the double box yeast Hmo1 and the single box yeast Nhp6A display strong binding preferences for nucleosomes over linker DNA, and both HMGB proteins destabilize and unwind DNA from the H2A–H2B dimers. However, unlike Nhp6A, Hmo1 also releases half of the DNA held by the (H3–H4)2 tetramer. This difference in nucleosome destabilization may explain why Nhp6A and Hmo1 function at different genomic sites. Hmo1 is enriched at highly transcribed ribosomal genes, known to be depleted of histones. In contrast, Nhp6A is found across euchromatin, pointing to a significant difference in cellular function.
Collapse
Affiliation(s)
| | - Ran Huo
- Department of Physics, Northeastern University, Boston, MA, USA
| | - Nicole Becker
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine and Science, Rochester, MN, USA
| | - Molly Nelson Holte
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine and Science, Rochester, MN, USA
| | - Uma M Muthurajan
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO, USA
| | - Ioulia Rouzina
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH, USA
| | - Karolin Luger
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO, USA.,Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - L James Maher
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine and Science, Rochester, MN, USA
| | | | - Mark C Williams
- Department of Physics, Northeastern University, Boston, MA, USA
| |
Collapse
|
150
|
Mechanical Energy before Chemical Energy at the Origins of Life? SCI 2019. [DOI: 10.3390/sci1020050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Forces and mechanical energy are prevalent in living cells. This may be because forces and mechanical energy preceded chemical energy at life’s origins. Mechanical energy is more readily available in non-living systems than the various other forms of energy used by living systems. Two possible prebiotic environments that might have provided mechanical energy are hot pools that experience wet/dry cycles and mica sheets as they move, open and shut, as heat pumps or in response to water movements.
Collapse
|