1
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Qian L, Cai W, Xu D, Bao Y, Lu ZY, Cui S. Single-Molecule Studies Reveal That Water Is a Special Solvent for Amylose and Natural Cellulose. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b00179] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Lu Qian
- Key Laboratory of Advanced Technologies of Materials (Ministry of Education), Southwest Jiaotong University, Chengdu 610031, China
| | - Wanhao Cai
- Key Laboratory of Advanced Technologies of Materials (Ministry of Education), Southwest Jiaotong University, Chengdu 610031, China
| | - Duo Xu
- State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, China
| | - Yu Bao
- Key Laboratory of Advanced Technologies of Materials (Ministry of Education), Southwest Jiaotong University, Chengdu 610031, China
| | - Zhong-yuan Lu
- State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, China
| | - Shuxun Cui
- Key Laboratory of Advanced Technologies of Materials (Ministry of Education), Southwest Jiaotong University, Chengdu 610031, China
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2
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Zhang S, Qian H, Liu Z, Ju H, Lu Z, Zhang H, Chi L, Cui S. Towards Unveiling the Exact Molecular Structure of Amorphous Red Phosphorus by Single‐Molecule Studies. Angew Chem Int Ed Engl 2019; 58:1659-1663. [DOI: 10.1002/anie.201811152] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 11/11/2018] [Indexed: 11/09/2022]
Affiliation(s)
- Song Zhang
- Key Laboratory of Advanced Technologies of Materials, (Ministry of Education)Southwest Jiaotong University Chengdu 610031 China
| | - Hu‐jun Qian
- State Key Laboratory of Supramolecular Structure and MaterialsInstitute of Theoretical ChemistryJilin University Changchun 130023 China
| | - Zhonghua Liu
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & DevicesInstitute of Functional Nano & Soft Materials (FUNSOM)Soochow University Suzhou 215123 China
| | - Hongyu Ju
- Key Laboratory of Advanced Technologies of Materials, (Ministry of Education)Southwest Jiaotong University Chengdu 610031 China
| | - Zhong‐yuan Lu
- State Key Laboratory of Supramolecular Structure and MaterialsInstitute of Theoretical ChemistryJilin University Changchun 130023 China
| | - Haiming Zhang
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & DevicesInstitute of Functional Nano & Soft Materials (FUNSOM)Soochow University Suzhou 215123 China
| | - Lifeng Chi
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & DevicesInstitute of Functional Nano & Soft Materials (FUNSOM)Soochow University Suzhou 215123 China
| | - Shuxun Cui
- Key Laboratory of Advanced Technologies of Materials, (Ministry of Education)Southwest Jiaotong University Chengdu 610031 China
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3
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Zhang S, Qian H, Liu Z, Ju H, Lu Z, Zhang H, Chi L, Cui S. Towards Unveiling the Exact Molecular Structure of Amorphous Red Phosphorus by Single‐Molecule Studies. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201811152] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Song Zhang
- Key Laboratory of Advanced Technologies of Materials, (Ministry of Education)Southwest Jiaotong University Chengdu 610031 China
| | - Hu‐jun Qian
- State Key Laboratory of Supramolecular Structure and MaterialsInstitute of Theoretical ChemistryJilin University Changchun 130023 China
| | - Zhonghua Liu
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & DevicesInstitute of Functional Nano & Soft Materials (FUNSOM)Soochow University Suzhou 215123 China
| | - Hongyu Ju
- Key Laboratory of Advanced Technologies of Materials, (Ministry of Education)Southwest Jiaotong University Chengdu 610031 China
| | - Zhong‐yuan Lu
- State Key Laboratory of Supramolecular Structure and MaterialsInstitute of Theoretical ChemistryJilin University Changchun 130023 China
| | - Haiming Zhang
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & DevicesInstitute of Functional Nano & Soft Materials (FUNSOM)Soochow University Suzhou 215123 China
| | - Lifeng Chi
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & DevicesInstitute of Functional Nano & Soft Materials (FUNSOM)Soochow University Suzhou 215123 China
| | - Shuxun Cui
- Key Laboratory of Advanced Technologies of Materials, (Ministry of Education)Southwest Jiaotong University Chengdu 610031 China
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4
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Qian L, Bao Y, Duan W, Cui S. Effects of Water Content of the Mixed Solvent on the Single-Molecule Mechanics of Amylose. ACS Macro Lett 2018; 7:672-676. [PMID: 35632975 DOI: 10.1021/acsmacrolett.8b00375] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
It is generally recognized that water is deeply involved in the structures and functions of DNA and proteins. For polysaccharides, however, the role of water remains unclear. Due to the force-induced conformational transition of the sugar rings, a fingerprint plateau can be observed in the single-chain force-extension (F-E) curves of amylose and some other polysaccharides in aqueous solutions. In this study, the effects of water content of the mixed solvents on the fingerprint plateau of amylose are explored by single-molecule AFM. The experimental results obtained in a series of water/alcohol mixed solvents clearly show that both the appearance and the fingerprint plateau height in the F-E curves of amylose are dependent on the water content. Since water is a good solvent for amylose but alcohols are not, the higher water content of a mixed solvent corresponds to a better solvent quality. Thus, the observed results can be associated with the solvent quality to amylose. The present study implies that water is not only a solvent but also an active constituent in the amylose solution.
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Affiliation(s)
- Lu Qian
- Key Laboratory of Advanced Technologies of Materials (Ministry of Education), Southwest Jiaotong University, Chengdu 610031, China
| | - Yu Bao
- Key Laboratory of Advanced Technologies of Materials (Ministry of Education), Southwest Jiaotong University, Chengdu 610031, China
| | - Weili Duan
- Key Laboratory of Advanced Technologies of Materials (Ministry of Education), Southwest Jiaotong University, Chengdu 610031, China
| | - Shuxun Cui
- Key Laboratory of Advanced Technologies of Materials (Ministry of Education), Southwest Jiaotong University, Chengdu 610031, China
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5
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Salzman GS, Ackerman SD, Ding C, Koide A, Leon K, Luo R, Stoveken HM, Fernandez CG, Tall GG, Piao X, Monk KR, Koide S, Araç D. Structural Basis for Regulation of GPR56/ADGRG1 by Its Alternatively Spliced Extracellular Domains. Neuron 2017; 91:1292-1304. [PMID: 27657451 DOI: 10.1016/j.neuron.2016.08.022] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2016] [Revised: 06/15/2016] [Accepted: 07/25/2016] [Indexed: 11/18/2022]
Abstract
Adhesion G protein-coupled receptors (aGPCRs) play critical roles in diverse neurobiological processes including brain development, synaptogenesis, and myelination. aGPCRs have large alternatively spliced extracellular regions (ECRs) that likely mediate intercellular signaling; however, the precise roles of ECRs remain unclear. The aGPCR GPR56/ADGRG1 regulates both oligodendrocyte and cortical development. Accordingly, human GPR56 mutations cause myelination defects and brain malformations. Here, we determined the crystal structure of the GPR56 ECR, the first structure of any complete aGPCR ECR, in complex with an inverse-agonist monobody, revealing a GPCR-Autoproteolysis-Inducing domain and a previously unidentified domain that we term Pentraxin/Laminin/neurexin/sex-hormone-binding-globulin-Like (PLL). Strikingly, PLL domain deletion caused increased signaling and characterizes a GPR56 splice variant. Finally, we show that an evolutionarily conserved residue in the PLL domain is critical for oligodendrocyte development in vivo. Thus, our results suggest that the GPR56 ECR has unique and multifaceted regulatory functions, providing novel insights into aGPCR roles in neurobiology.
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Affiliation(s)
- Gabriel S Salzman
- Biophysical Sciences Program, The University of Chicago, Chicago, IL 60637, USA; Medical Scientist Training Program, The University of Chicago, Chicago, IL 60637, USA; Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Sarah D Ackerman
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Chen Ding
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Akiko Koide
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Katherine Leon
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Rong Luo
- Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Hannah M Stoveken
- Departments of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Celia G Fernandez
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Gregory G Tall
- Departments of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Xianhua Piao
- Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Kelly R Monk
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Shohei Koide
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA.
| | - Demet Araç
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA.
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6
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Reiner JE, Balijepalli A, Robertson JWF, Campbell J, Suehle J, Kasianowicz JJ. Disease Detection and Management via Single Nanopore-Based Sensors. Chem Rev 2012; 112:6431-51. [DOI: 10.1021/cr300381m] [Citation(s) in RCA: 195] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Joseph E. Reiner
- Department of Physics, Virginia
Commonwealth University, 701 W. Grace Street, Richmond, Virginia 23284,
United States
| | - Arvind Balijepalli
- Physical
Measurement Laboratory,
National Institute of Standards and Technology, Gaithersburg, Maryland
20899-8120, United States
- Laboratory of Computational Biology,
National Heart Lung and Blood Institute, Rockville, Maryland 20852,
United States
| | - Joseph W. F. Robertson
- Physical
Measurement Laboratory,
National Institute of Standards and Technology, Gaithersburg, Maryland
20899-8120, United States
| | - Jason Campbell
- Physical
Measurement Laboratory,
National Institute of Standards and Technology, Gaithersburg, Maryland
20899-8120, United States
| | - John Suehle
- Physical
Measurement Laboratory,
National Institute of Standards and Technology, Gaithersburg, Maryland
20899-8120, United States
| | - John J. Kasianowicz
- Physical
Measurement Laboratory,
National Institute of Standards and Technology, Gaithersburg, Maryland
20899-8120, United States
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7
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Abstract
We use single-molecule force clamp spectroscopy (SMFCS) to explore the reactivity of tris(2-carboxyethyl)phosphine (TCEP), 1, 4-dl-dithiothreitol (DTT) and hydrosulfide anion (HS(-)) on disulfide bonds within a mechanically stretched polypeptide. The single-bond level bimolecular nucleophilic substitution (S(N)2) events are recorded at a series of precisely controlled temperatures so that the Arrhenius kinetic parameters, that is, the height of the activation energy barrier (E(a)) and the attempting frequency (A) of the chemical reactions, can be determined. The values of A are typically at the order of 10(7) M(-1) s(-1), which is far lower than that predicted by the transition-state theory, in which A is given by k(B)T/h and around 10(12) M(-1) s(-1) at room temperature. Furthermore, E(a) is derived to be 30-40 kJ/mol, which can be lowered by ∼6-8% with every 100 pN mechanical force applied. The correlation of the A and E(a) with the molecular structures reveals that the relative magnitude of these two parameters cannot be simply judged from the size of the molecule or the nucleophilicity of the attacking atom. The comparison of the influences on the reaction rate induced by force and temperature indicates an equivalent accelerating effect by every 50 pN or 10 K increment, giving for the first time the relationship between mechanical and thermal effects on a single-molecule S(N)2 chemical reaction.
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Affiliation(s)
| | - Julio M. Fernández
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
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8
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Abstract
Single-molecule force-clamp spectroscopy offers a novel platform for mechanically denaturing proteins by applying a constant force to a polyprotein. A powerful emerging application of the technique is that, by introducing a disulfide bond in each protein module, the chemical kinetics of disulfide bond cleavage under different stretching forces can be probed at the single-bond level. Even at forces much lower than that which can rupture the chemical bond, the breaking of the S-S bond at the presence of various chemical reducing agents is significantly accelerated. Our previous work demonstrated that the rate of thiol/disulfide exchange reaction is force-dependent and well-described by an Arrhenius term of the form r = A(exp((FΔx(r) - E(a))/k(B)T)[nucleophile]). From Arrhenius fits to the force dependency of the reduction rate, we measured the bond elongation parameter, Δx(r), along the reaction coordinate to the transition state of the S(N)2 reaction cleaved by different nucleophiles and enzymes, never before observed by any other technique. For S-S cleavage by various reducing agents, obtaining the Δx(r) value can help depicting the energy landscapes and elucidating the mechanisms of the reactions at the single-molecule level. Small nucleophiles, such as 1,4-dl-dithiothreitol (DTT), tris(2-carboxyethyl)phosphine (TCEP), and l-cysteine, react with the S-S bond with monotonically increasing rates under the applied force, while thioredoxin enzymes exhibit both stretching-favored and -resistant reaction-rate regimes. These measurements demonstrate the power of the single-molecule force-clamp spectroscopy approach in providing unprecedented access to chemical reactions.
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9
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Serpe MJ, Kersey FR, Whitehead JR, Wilson SM, Clark RL, Craig SL. A Simple and Practical Spreadsheet-Based Method to Extract Single-Molecule Dissociation Kinetics from Variable Loading-Rate Force Spectroscopy Data. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2008; 112:19163-19167. [PMID: 20011580 PMCID: PMC2700757 DOI: 10.1021/jp806649a] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Affiliation(s)
- Michael J. Serpe
- Department of Chemistry, University of Rochester
- Center for Biologically Inspired Materials and Material Systems, University of Rochester
| | - Farrell R. Kersey
- Department of Chemistry, University of Rochester
- Center for Biologically Inspired Materials and Material Systems, University of Rochester
| | - Jason R. Whitehead
- Department of Chemistry, University of Rochester
- Center for Biologically Inspired Materials and Material Systems, University of Rochester
| | - Scott M. Wilson
- Department of Mechanical Engineering and Materials Science, University of Rochester
- Center for Biologically Inspired Materials and Material Systems, University of Rochester
| | - Robert L. Clark
- School of Engineering and Applied Sciences, University of Rochester
| | - Stephen L. Craig
- Department of Chemistry, University of Rochester
- Center for Biologically Inspired Materials and Material Systems, University of Rochester
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10
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Cao Y, Li H. Engineered elastomeric proteins with dual elasticity can be controlled by a molecular regulator. NATURE NANOTECHNOLOGY 2008; 3:512-516. [PMID: 18685641 DOI: 10.1038/nnano.2008.168] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2008] [Accepted: 05/23/2008] [Indexed: 05/26/2023]
Abstract
Elastomeric proteins are molecular springs that confer excellent mechanical properties to many biological tissues and biomaterials. Depending on the role performed by the tissue or biomaterial, elastomeric proteins can behave as molecular springs or shock absorbers. Here we combine single-molecule atomic force microscopy and protein engineering techniques to create elastomeric proteins that can switch between two distinct types of mechanical behaviour in response to the binding of a molecular regulator. The proteins are mechanically labile by design and behave as entropic springs with an elasticity that is governed by their configurational entropy. However, when a molecular regulator binds to the protein, it switches into a mechanically stable state and can act as a shock absorber. These engineered proteins effectively mimic and combine the two extreme forms of elastic behaviour found in natural elastomeric proteins, and thus represent a new type of smart nanomaterial that will find potential applications in nanomechanics and material sciences.
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11
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Valle F, Sandal M, Samorì B. The interplay between chemistry and mechanics in the transduction of a mechanical signal into a biochemical function. Phys Life Rev 2007. [DOI: 10.1016/j.plrev.2007.06.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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12
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Grandi F, Sandal M, Guarguaglini G, Capriotti E, Casadio R, Samorì B. Hierarchical mechanochemical switches in angiostatin. Chembiochem 2007; 7:1774-82. [PMID: 16991168 DOI: 10.1002/cbic.200600227] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
We wish to propose a novel mechanism by which the triggering of a biochemical signal can be controlled by the hierarchical coupling between a protein redox equilibrium and an external mechanical force. We have characterized this mechanochemical mechanism in angiostatin, and we have evidence that it can switch the access to partially unfolded structures of this protein. We have identified a metastable intermediate that is specifically accessible under thioredoxin-rich reducing conditions, like those met by angiostatin on the surface of a tumor cell. The structure of the same intermediate accounts for the unexplained antiangiogenic activity of angiostatin. These findings demonstrate a new link between redox biology and mechanically regulated processes.
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Affiliation(s)
- Fabio Grandi
- Department of Biochemistry, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
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13
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Ainavarapu SRK, Brujic J, Huang HH, Wiita AP, Lu H, Li L, Walther KA, Carrion-Vazquez M, Li H, Fernandez JM. Contour length and refolding rate of a small protein controlled by engineered disulfide bonds. Biophys J 2006; 92:225-33. [PMID: 17028145 PMCID: PMC1697845 DOI: 10.1529/biophysj.106.091561] [Citation(s) in RCA: 228] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The introduction of disulfide bonds into proteins creates additional mechanical barriers and limits the unfolded contour length (i.e., the maximal extension) measured by single-molecule force spectroscopy. Here, we engineer single disulfide bonds into four different locations of the human cardiac titin module (I27) to control the contour length while keeping the distance to the transition state unchanged. This enables the study of several biologically important parameters. First, we are able to precisely determine the end-to-end length of the transition state before unfolding (53 Angstrom), which is longer than the end-to-end length of the protein obtained from NMR spectroscopy (43 Angstrom). Second, the measured contour length per amino acid from five different methods (4.0 +/- 0.2 Angstrom) is longer than the end-to-end length obtained from the crystal structure (3.6 Angstrom). Our measurement of the contour length takes into account all the internal degrees of freedom of the polypeptide chain, whereas crystallography measures the end-to-end length within the "frozen" protein structure. Furthermore, the control of contour length and therefore the number of amino acids unraveled before reaching the disulfide bond (n) facilitates the test of the chain length dependence on the folding time (tau(F)). We find that both a power law scaling tau(F) lambda n(lambda) with lambda = 4.4, and an exponential scaling with n(0.6) fit the data range, in support of different protein-folding scenarios.
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14
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Wiita AP, Ainavarapu SRK, Huang HH, Fernandez JM. Force-dependent chemical kinetics of disulfide bond reduction observed with single-molecule techniques. Proc Natl Acad Sci U S A 2006; 103:7222-7. [PMID: 16645035 PMCID: PMC1464324 DOI: 10.1073/pnas.0511035103] [Citation(s) in RCA: 281] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The mechanism by which mechanical force regulates the kinetics of a chemical reaction is unknown. Here, we use single-molecule force-clamp spectroscopy and protein engineering to study the effect of force on the kinetics of thiol/disulfide exchange. Reduction of disulfide bonds through the thiol/disulfide exchange chemical reaction is crucial in regulating protein function and is known to occur in mechanically stressed proteins. We apply a constant stretching force to single engineered disulfide bonds and measure their rate of reduction by DTT. Although the reduction rate is linearly dependent on the concentration of DTT, it is exponentially dependent on the applied force, increasing 10-fold over a 300-pN range. This result predicts that the disulfide bond lengthens by 0.34 A at the transition state of the thiol/disulfide exchange reaction. Our work at the single bond level directly demonstrates that thiol/disulfide exchange in proteins is a force-dependent chemical reaction. Our findings suggest that mechanical force plays a role in disulfide reduction in vivo, a property that has never been explored by traditional biochemistry. Furthermore, our work also indicates that the kinetics of any chemical reaction that results in bond lengthening will be force-dependent.
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Affiliation(s)
- Arun P. Wiita
- *Department of Biological Sciences and
- Graduate Program in Neurobiology and Behavior, Columbia University, New York, NY 10027
| | | | | | - Julio M. Fernandez
- *Department of Biological Sciences and
- To whom correspondence should be addressed at:
Department of Biological Sciences, Columbia University, 1011 Fairchild Center, 1212 Amsterdam Avenue, MC 2449, New York, NY 10027. E-mail:
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15
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Sandal M, Grandi F, Samorì B. Single molecule force spectroscopy discovers mechanochemical switches in biology: The case of the disulfide bond. POLYMER 2006. [DOI: 10.1016/j.polymer.2005.12.084] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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16
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Cao Y, Lam C, Wang M, Li H. Nonmechanical Protein Can Have Significant Mechanical Stability. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200502623] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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17
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Cao Y, Lam C, Wang M, Li H. Nonmechanical Protein Can Have Significant Mechanical Stability. Angew Chem Int Ed Engl 2006; 45:642-5. [PMID: 16345105 DOI: 10.1002/anie.200502623] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Yi Cao
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, BC, Canada
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18
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Abstract
The use of chemically modified atomic force microscopy (AFM) probes allows us to measure the surface charges of supported planar lipid bilayers with high sensitivity through the force spectroscopy operation mode. By controlling the chemistry of the tip, we can perform a classical analytical chemistry titration where the titration agent is a weak acid (attached to the AFM tip) with the particularity of being performed in surface rather than in solution and, especially, at the nanometric scale. Thus, the AFM tip acts as a real "nanosensor". The approaching curves of the force plots reveal that electrostatic interactions between the tip and the supported membrane play a key role. Besides, the plot of the adhesion force (measured from the retracting curve of the force plots) versus pH displays a nonsigmoidal shape with a peak in the adhesion force attributed to high-energy hydrogen bonds. One of these peaks corresponds to the pKa of the surface under study and the other to the pKa of the titrating probe attached to the tip.
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Affiliation(s)
- Sergi Garcia-Manyes
- Department of Physical Chemistry, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain
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19
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Brockwell DJ, Beddard GS, Paci E, West DK, Olmsted PD, Smith DA, Radford SE. Mechanically unfolding the small, topologically simple protein L. Biophys J 2005; 89:506-19. [PMID: 15863479 PMCID: PMC1366550 DOI: 10.1529/biophysj.105.061465] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
beta-sheet proteins are generally more able to resist mechanical deformation than alpha-helical proteins. Experiments measuring the mechanical resistance of beta-sheet proteins extended by their termini led to the hypothesis that parallel, directly hydrogen-bonded terminal beta-strands provide the greatest mechanical strength. Here we test this hypothesis by measuring the mechanical properties of protein L, a domain with a topology predicted to be mechanically strong, but with no known mechanical function. A pentamer of this small, topologically simple protein is resistant to mechanical deformation over a wide range of extension rates. Molecular dynamics simulations show the energy landscape for protein L is highly restricted for mechanical unfolding and that this protein unfolds by the shearing apart of two structural units in a mechanism similar to that proposed for ubiquitin, which belongs to the same structural class as protein L, but unfolds at a significantly higher force. These data suggest that the mechanism of mechanical unfolding is conserved in proteins within the same fold family and demonstrate that although the topology and presence of a hydrogen-bonded clamp are of central importance in determining mechanical strength, hydrophobic interactions also play an important role in modulating the mechanical resistance of these similar proteins.
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Affiliation(s)
- David J Brockwell
- School of Biochemistry and Microbiology, Institute of Molecular Biophysics, Centre for Chemical Dynamics, University of Leeds, Leeds, United Kingdom.
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20
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Xue-Shun J, Yong-Min Z. Reductive Cleavage of the Carbon-sulfur Bond by Samarium/Cp2TiCl2 System for the Synthesis of Dialkyl Disulfides. CHINESE J CHEM 2005. [DOI: 10.1002/cjoc.200590303] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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21
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Bhasin N, Carl P, Harper S, Feng G, Lu H, Speicher DW, Discher DE. Chemistry on a single protein, vascular cell adhesion molecule-1, during forced unfolding. J Biol Chem 2004; 279:45865-74. [PMID: 15308645 DOI: 10.1074/jbc.m404103200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Proteins of many types experience tensile forces in their normal function, and vascular cell adhesion molecule-1 (VCAM-1) is typical in this. VCAM has seven Ig domains, and each has a disulfide bond (-S-S-) buried in its core that covalently stabilizes about half of each domain against unfolding. VCAM is extended here by single molecule atomic force microscopy in the presence or absence of reducing agents. In the absence of reducing agent, a sawtooth pattern of forced unfolding reveals an average period and total length consistent with disulfide locations in VCAM. With increasing reducing agent, accessible disulfides are specifically reduced (to SH); the average period for unfolding increases up to saturation together with additional metrics of unfolding. Steered molecular dynamics simulations of unfolding indeed show that the core disulfide bond is solvent-exposed in the very earliest stages of protein extension. Michaelis-Menten kinetics emerge with reduction catalyzed by force (tau(reduction) approximately 10(-4) s). The results establish single molecule reduction, one bond at a time, and show that mechanical forces can play a key role in modulating the redox state of cell adhesion proteins that are invariably stressed in cell adhesion.
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Affiliation(s)
- Nishant Bhasin
- Systems Biology and Polymer Engineering Laboratory, the Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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