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Rajput SS, Singh SB, Subramanyam D, Patil S. Soft glassy rheology of single cells with pathogenic protein aggregates. SOFT MATTER 2024; 20:6266-6274. [PMID: 39054893 DOI: 10.1039/d4sm00595c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/27/2024]
Abstract
A correlation between the mechanical properties of cells and various diseases has been emerging in recent years. Atomic force microscopy (AFM) has been widely used to measure a single cell's apparent Young's modulus by treating it as a fully elastic object. More recently, quantitative characterization of the complete viscoelasticity of single cells has become possible. We performed AFM-based nano-indentation experiments on hemocytes isolated from third instar larvae to determine their viscoelasticity and found that live hemocytes, like many other cells, follow a scale-free power-law rheology (PLR) akin to soft glasses. Further, we examined the changes in the rheological response of hemocytes in the presence of pathogenic protein aggregates known to cause neurodegenerative diseases such as Huntington's disorder and amyotrophic lateral sclerosis. Our results show that cells lose their fluidity and appear more solid-like in the presence of certain aggregates, in a manner correlated to actin reorganization. More solid-like cells also display reduced intracellular transport through clathrin-mediated endocytosis (CME). However, the cell's rheology remains largely unaffected and is similar to that of wild-type (WT) hemocytes, if aggregates do not perturb the actin organization and CME. Moreover, the fluid-like nature was significantly recovered when actin organization was rescued by overexpressing specific actin interacting proteins or chaperones. Our study, for the first time, underscores a direct correlation between parameters governing glassy dynamics, actin organization and CME.
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Affiliation(s)
- Shatruhan Singh Rajput
- Department of Physics, Indian Institute of Science Education and Research, Pune 411008, India
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
| | - Surya Bansi Singh
- National Centre for Cell Science, SP Pune University Campus, Pune 411007, India.
- SP Pune University, Pune 411007, India
| | - Deepa Subramanyam
- National Centre for Cell Science, SP Pune University Campus, Pune 411007, India.
| | - Shivprasad Patil
- Department of Physics, Indian Institute of Science Education and Research, Pune 411008, India.
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2
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Hu J, Wang Z, Jiang D, Gao M, Dong L, Liu M, Song Z. pH-induced changes in IgE molecules measured by atomic force microscopy. Microsc Res Tech 2024. [PMID: 39044615 DOI: 10.1002/jemt.24660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 06/23/2024] [Accepted: 07/09/2024] [Indexed: 07/25/2024]
Abstract
The environment surrounding proteins is tightly linked to its dynamics, which can significantly influence the conformation of proteins. This study focused on the effect of pH conditions on the ultrastructure of Immunoglobulin E (IgE) molecules. Herein, the morphology, height, and area of IgE molecules incubated at different pH were imaged by atomic force microscopy (AFM), and the law of IgE changes induced by pH value was explored. The experiment results indicated that the morphology, height and area of IgE molecules are pH dependent and highly sensitive. In particular, IgE molecules were more likely to present small-sized ellipsoids under acidic conditions, while IgE molecules tend to aggregate into large-sized flower-like structures under alkaline conditions. In addition, it was found that the height of IgE first decreased and then increased with the increase of pH, while the area of IgE increased with the increase of pH. This work provides valuable information for further study of IgE, and the methodological approach used in this study is expected to developed into AFM to investigate the changes of IgE molecules mediated by other physical and chemical factors. RESEARCH HIGHLIGHTS: The ultrastructure of IgE molecules is pH dependent and highly sensitive. IgE molecules were tend to present small-sized ellipsoids under acidic pH. Alkaline pH drives IgE self-assembly into flower-like aggregates.
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Affiliation(s)
- Jing Hu
- School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun, China
- Centre for Opto/Bio-Nano Measurement and Manufacturing, Zhongshan Institute of Changchun University of Science and Technology, Zhongshan, China
- Ministry of Education Key Laboratory for Cross-Scale Micro and Nano Manufacturing, Changchun University of Science and Technology, Changchun, China
- International Research Centre for Nano Handling and Manufacturing of China, Changchun University of Science and Technology, Changchun, China
| | - Zuobin Wang
- Centre for Opto/Bio-Nano Measurement and Manufacturing, Zhongshan Institute of Changchun University of Science and Technology, Zhongshan, China
- Ministry of Education Key Laboratory for Cross-Scale Micro and Nano Manufacturing, Changchun University of Science and Technology, Changchun, China
- International Research Centre for Nano Handling and Manufacturing of China, Changchun University of Science and Technology, Changchun, China
- JR3CN & IRAC, University of Bedfordshire, Luton, UK
| | - Dayong Jiang
- School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun, China
| | - Mingyan Gao
- Centre for Opto/Bio-Nano Measurement and Manufacturing, Zhongshan Institute of Changchun University of Science and Technology, Zhongshan, China
| | - Litong Dong
- Centre for Opto/Bio-Nano Measurement and Manufacturing, Zhongshan Institute of Changchun University of Science and Technology, Zhongshan, China
- Ministry of Education Key Laboratory for Cross-Scale Micro and Nano Manufacturing, Changchun University of Science and Technology, Changchun, China
- International Research Centre for Nano Handling and Manufacturing of China, Changchun University of Science and Technology, Changchun, China
| | - Mengnan Liu
- Centre for Opto/Bio-Nano Measurement and Manufacturing, Zhongshan Institute of Changchun University of Science and Technology, Zhongshan, China
- Ministry of Education Key Laboratory for Cross-Scale Micro and Nano Manufacturing, Changchun University of Science and Technology, Changchun, China
- International Research Centre for Nano Handling and Manufacturing of China, Changchun University of Science and Technology, Changchun, China
| | - Zhengxun Song
- Centre for Opto/Bio-Nano Measurement and Manufacturing, Zhongshan Institute of Changchun University of Science and Technology, Zhongshan, China
- Ministry of Education Key Laboratory for Cross-Scale Micro and Nano Manufacturing, Changchun University of Science and Technology, Changchun, China
- International Research Centre for Nano Handling and Manufacturing of China, Changchun University of Science and Technology, Changchun, China
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Świątek A, Kuczera K, Szoszkiewicz R. Effects of Proline on Internal Friction in Simulated Folding Dynamics of Several Alanine-Based α-Helical Peptides. J Phys Chem B 2024; 128:3856-3869. [PMID: 38606880 PMCID: PMC11056985 DOI: 10.1021/acs.jpcb.4c00623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 03/13/2024] [Accepted: 04/01/2024] [Indexed: 04/13/2024]
Abstract
We have studied in silico the effect of proline, a model cosolvent, on local and global friction coefficients in (un)folding of several typical alanine-based α-helical peptides. Local friction is related to dwell times of a single, ensemble-averaged hydrogen bond (HB) within each peptide. Global friction is related to energy dissipated in a series of configurational changes of each peptide experienced by increasing the number of HBs during folding. Both of these approaches are important in relation to future atomic force microscopic-based measurements of internal friction via force-clamp single-molecule force spectroscopy. Molecular dynamics (MD) simulations for six peptides, namely, ALA5, ALA8, ALA15, ALA21, (AAQAA)3, and H2N-GN(AAQAA)2G-COONH2, have been conducted at 2 and 5 M proline solutions in water. Using previously obtained MD data for these peptides in pure water as well as upgraded theoretical models, we obtained variations of local and global internal friction coefficients as a function of solution viscosity. The results showed the substantial role of proline in stabilizing the folded state and slowing the overall folding dynamics. Consequently, larger friction coefficients were obtained at larger viscosities. The local and global internal friction, i.e., respective, friction coefficients approximated to zero viscosity, was also obtained. The evolution of friction coefficients with viscosity was weakly dependent on the number of concurrent folding pathways but was rather dominated by a stabilizing effect of proline on the folded states. Obtained values of local and global internal friction showed qualitatively similar results and a clear dependency on the structure of the studied peptide.
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Affiliation(s)
- Adam Świątek
- Faculty of Chemistry,
Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Krzysztof Kuczera
- Department
of Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
- Department of Molecular Biosciences, The
University of Kansas, Lawrence, Kansas 66045, United States
| | - Robert Szoszkiewicz
- Faculty of Chemistry,
Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland
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4
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Wosztyl A, Kuczera K, Szoszkiewicz R. Analytical Approaches for Deriving Friction Coefficients for Selected α-Helical Peptides Based Entirely on Molecular Dynamics Simulations. J Phys Chem B 2022; 126:8901-8912. [PMID: 36300354 PMCID: PMC9661531 DOI: 10.1021/acs.jpcb.2c03076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
In this paper we derive analytically from molecular dynamics (MD) simulations the friction coefficients related to conformational transitions within several model peptides with α-helical structures. We study a series of alanine peptides with various length from ALA5 to ALA21 as well as their two derivatives, the (AAQAA)3 peptide and a 13-residue KR1 peptide that is a derivative of the (AAQAA)2 peptide with the formula GN(AAQAA)2G. We use two kinds of approaches to derive their friction coefficients. In the local approach, friction associated with fluctuations of single hydrogen bonds are studied. In the second approach, friction coefficients associated with a folding transitions within the studied peptides are obtained. In both cases, the respective friction coefficients differentiated very well the subtle structural changes between studied peptides and compared favorably to experimentally available data.
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Affiliation(s)
- Aleksandra Wosztyl
- Faculty
of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02-089Warsaw, Poland
| | - Krzysztof Kuczera
- Department
of Chemistry, The University of Kansas, Lawrence, Kansas66045, United States,Department
of Molecular Biosciences, The University
of Kansas, Lawrence, Kansas66045, United States,
| | - Robert Szoszkiewicz
- Faculty
of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02-089Warsaw, Poland,
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Deopa SPS, Rajput SS, Kumar A, Patil S. Direct and Simultaneous Measurement of the Stiffness and Internal Friction of a Single Folded Protein. J Phys Chem Lett 2022; 13:9473-9479. [PMID: 36198174 DOI: 10.1021/acs.jpclett.2c02257] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The nanomechanical response of a folded single protein, the natural nanomachine responsible for myriad biological processes, provides insight into its function. The conformational flexibility of a folded state, characterized by its viscoelasticity, allows proteins to adopt different shapes to perform their function. Despite efforts, its direct measurement has not been possible so far. We present a direct and simultaneous measurement of the stiffness and internal friction of the folded domains of the protein titin using a special interferometer based atomic force microscope. We analyzed the data by carefully separating different contributions affecting the response of the experimental probe to obtain the folded state's viscoelasticity. Above ∼95 pN of force, the individual immunoglobulins of titin transition from an elastic solid-like native state to a soft viscoelastic intermediate.
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Affiliation(s)
- Surya Pratap S Deopa
- Department of Physics, Indian Institute of Science Education & Research, Pune411008, Maharashtra, India
| | - Shatruhan Singh Rajput
- Department of Physics, Indian Institute of Science Education & Research, Pune411008, Maharashtra, India
| | - Aadarsh Kumar
- Department of Physics, Indian Institute of Science Education & Research, Pune411008, Maharashtra, India
| | - Shivprasad Patil
- Department of Physics, Indian Institute of Science Education & Research, Pune411008, Maharashtra, India
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Ahlawat V, Deopa SPS, Patil S. Quantitative Elasticity of Flexible Polymer Chains Using Interferometer-Based AFM. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:526. [PMID: 35159871 PMCID: PMC8839736 DOI: 10.3390/nano12030526] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 01/19/2022] [Accepted: 01/27/2022] [Indexed: 12/04/2022]
Abstract
We estimate the elasticity of single polymer chains using atomic force microscope (AFM)-based oscillatory experiments. An accurate estimate of elasticity using AFM is limited by assumptions in describing the dynamics of an oscillating cantilever. Here, we use a home-built fiber-interferometry-based detection system that allows a simple and universal point-mass description of cantilever oscillations. By oscillating the cantilever base and detecting changes in cantilever oscillations with an interferometer, we extracted stiffness versus extension profiles for polymers. For polyethylene glycol (PEG) in a good solvent, stiffness-extension data showed significant deviation from conventional force-extension curves (FECs) measured in constant velocity pulling experiments. Furthermore, modeling stiffness data with an entropic worm-like chain (WLC) model yielded a persistence length of (0.5 ± 0.2 nm) compared to anomaly low value (0.12 nm ± 0.01) in conventional pulling experiments. This value also matched well with equilibrium measurements performed using magnetic tweezers. In contrast, polystyrene (PS) in a poor solvent, like water, showed no deviation between the two experiments. However, the stiffness profile for PS in good solvent (8M Urea) showed significant deviation from conventional force-extension curves. We obtained a persistence length of (0.8 ± 0.2 nm) compared to (0.22 nm ± 0.01) in pulling experiments. Our unambiguous measurements using interferometer yield physically acceptable values of persistence length. It validates the WLC model in good solvents but suggests caution for its use in poor solvents.
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Affiliation(s)
| | | | - Shivprasad Patil
- Department of Physics, Indian Institute of Science Education and Research (IISER) Pune, Pashan Road, Pune 411008, India; (V.A.); (S.P.S.D.)
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Rajput SS, Deopa SPS, Ajith VJ, Kamerkar SC, Patil S. Validity of point-mass model in off-resonance dynamic atomic force microscopy. NANOTECHNOLOGY 2021; 32:405702. [PMID: 34144547 DOI: 10.1088/1361-6528/ac0cb1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Accepted: 06/18/2021] [Indexed: 06/12/2023]
Abstract
The quantitative measurement of viscoelasticity of nano-scale entities is an important goal of nanotechnology research and there is considerable progress with advent of dynamic atomic force microscopy. The hydrodynamics of cantilever, the force sensor in AFM measurements, plays a pivotal role in quantitative estimates of nano-scale viscoelasticity. The point-mass (PM) model, wherein the AFM cantilever is approximated as a point-mass with mass-less spring is widely used in dynamic AFM analysis and its validity, particularly in liquid environments, is debated. It is suggested that the cantilever must be treated as a continuous rectangular beam to obtain accurate estimates of nano-scale viscoelasticity of materials it is probing. Here, we derived equations, which relate stiffness and damping coefficient of the material under investigation to measured parameters, by approximating cantilever as a point-mass and also considering the full geometric details. These equations are derived for both tip-excited as well as base-excited cantilevers. We have performed off-resonance dynamic atomic force spectroscopy on a single protein molecule to investigate the validity of widely used PM model. We performed measurements with AFMs equipped with different cantilever excitation methods as well as detection schemes to measure cantilever response. The data was analyzed using both, continuous beam model and the PM model. We found that both models yield same results when the experiments are performed in truly off-resonance regime with small amplitudes and the cantilever stiffness is much higher than the interaction stiffness. Our findings suggest that a simple PM approximation based model is adequate to describe the dynamics, provided care is taken while performing experiments so that the approximations used in these models are valid.
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Affiliation(s)
- Shatruhan Singh Rajput
- Department of Physics, Indian Institute of Science Education and Research Pune, Dr Homi Bhabha Road, Pashan, Pune 411008, India
| | - Surya Pratap S Deopa
- Department of Physics, Indian Institute of Science Education and Research Pune, Dr Homi Bhabha Road, Pashan, Pune 411008, India
| | - V J Ajith
- Department of Physics, Indian Institute of Science Education and Research Pune, Dr Homi Bhabha Road, Pashan, Pune 411008, India
| | - Sukrut C Kamerkar
- Department of Biology, Indian Institute of Science Education and Research Pune, Dr Homi Bhabha Road, Pashan, Pune 411008, India
| | - Shivprasad Patil
- Department of Physics, Indian Institute of Science Education and Research Pune, Dr Homi Bhabha Road, Pashan, Pune 411008, India
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