1
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James A, Nayar D. Contrasting behavior of urea in strengthening and weakening confinement effects on polymer collapse. J Chem Phys 2024; 161:164904. [PMID: 39440764 DOI: 10.1063/5.0227153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2024] [Accepted: 10/07/2024] [Indexed: 10/25/2024] Open
Abstract
Biomolecules inhabit a crowded living cell that is packed with high concentrations of cosolutes and macromolecules that result in restricted, confined volumes for biomolecular dynamics. To understand the impact of crowding on the biomolecular structure, the combined effects of the cosolutes (such as urea) and confinement need to be accounted for. This study involves examining these effects on the collapse equilibria of three model 32-mer polymers, which are simplified models of hydrophobic, charge-neutral, and uncharged hydrophilic polymers, using molecular dynamics simulations. The introduction of confinement promotes the collapse of all three polymers. Interestingly, addition of urea weakens the collapse of the confined hydrophobic polymer, leading to non-additive effects, whereas for the hydrophilic polymers, urea enhances the confinement effects by enhancing polymer collapse (or decreasing the polymer unfolding), thereby exhibiting an additive effect. The unfavorable dehydration energy opposes collapse in the confined hydrophobic and charge-neutral polymers under the influence of urea. However, the collapse is driven mainly by the favorable change in polymer-solvent entropy. The confined hydrophilic polymer, which tends to unfold in bulk water, is seen to have reduced unfolding in the presence of urea due to the stabilizing of the collapsed state by urea via cohesive bridging interactions. Therefore, there is a complex balance of competing factors, such as polymer chemistry and polymer-water and polymer-cosolute interactions, beyond volume exclusion effects, which determine the collapse equilibria under confinement. The results have implications to understand the altering of the free energy landscape of proteins in the confined living cell environment.
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Affiliation(s)
- Alen James
- Department of Physics, Indian Institute of Science Education and Research Tirupati, Tirupati, Andhra Pradesh 517619, India
| | - Divya Nayar
- Department of Materials Science and Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
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2
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Zhu B, Zhang C, Wang J, Jia C, Lu T, Dai L, Chen T. Scaling Laws for Protein Folding under Confinement. J Phys Chem Lett 2024; 15:10138-10145. [PMID: 39340464 DOI: 10.1021/acs.jpclett.4c02098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/30/2024]
Abstract
Spatial confinement significantly affects protein folding. Without the confinement provided by chaperones, many proteins cannot fold correctly. However, the quantitative effect of confinement on protein folding remains elusive. In this study, we observed scaling laws between the variation in folding transition temperature and the size of confinement, (Tf - Tfbulk)/Tfbulk ∼ L-ν. The scaling exponent v is significantly influenced by both the protein's topology and folding cooperativity. Specifically, for a given protein, v can decrease as the folding cooperativity of the model increases, primarily due to the heightened sensitivity of the unfolded state energy to changes in cage size. For proteins with diverse topologies, variations in topological complexity influence scaling exponents in multiple ways. Notably, v exhibits a clear positive correlation with contact order and the proportion of nonlocal contacts, as this complexity significantly enhances the sensitivity of entropy loss in the unfolded state. Furthermore, we developed a novel scaling argument yielding 5/3 ≤ ν ≤ 10/3, consistent with the simulation results.
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Affiliation(s)
- Bin Zhu
- College of Chemistry and Materials Science, Northwest University, Xi'an, 710127, China
| | - Chenxi Zhang
- College of Chemistry and Materials Science, Northwest University, Xi'an, 710127, China
| | - Jiwei Wang
- College of Chemistry and Materials Science, Northwest University, Xi'an, 710127, China
| | - Chuandong Jia
- College of Chemistry and Materials Science, Northwest University, Xi'an, 710127, China
| | - Teng Lu
- Computer Network Information Center, Chinese Academy of Sciences, Beijing 100083, China
| | - Liang Dai
- Department of Physics, City University of Hong Kong, Hong Kong 999077, China
- Shenzhen Research Institute, City University of Hong Kong, Shenzhen 518057, P. R. China
| | - Tao Chen
- College of Chemistry and Materials Science, Northwest University, Xi'an, 710127, China
- Key Laboratory of Polymer Processing Engineering (South China University of Technology), Ministry of Education, Guangzhou 510641, China
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3
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Bajpai S, Petkov BK, Tong M, Abreu CRA, Nair NN, Tuckerman ME. An interoperable implementation of collective-variable based enhanced sampling methods in extended phase space within the OpenMM package. J Comput Chem 2023; 44:2166-2183. [PMID: 37464902 DOI: 10.1002/jcc.27182] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 05/30/2023] [Accepted: 06/06/2023] [Indexed: 07/20/2023]
Abstract
Collective variable (CV)-based enhanced sampling techniques are widely used today for accelerating barrier-crossing events in molecular simulations. A class of these methods, which includes temperature accelerated molecular dynamics (TAMD)/driven-adiabatic free energy dynamics (d-AFED), unified free energy dynamics (UFED), and temperature accelerated sliced sampling (TASS), uses an extended variable formalism to achieve quick exploration of conformational space. These techniques are powerful, as they enhance the sampling of a large number of CVs simultaneously compared to other techniques. Extended variables are kept at a much higher temperature than the physical temperature by ensuring adiabatic separation between the extended and physical subsystems and employing rigorous thermostatting. In this work, we present a computational platform to perform extended phase space enhanced sampling simulations using the open-source molecular dynamics engine OpenMM. The implementation allows users to have interoperability of sampling techniques, as well as employ state-of-the-art thermostats and multiple time-stepping. This work also presents protocols for determining the critical parameters and procedures for reconstructing high-dimensional free energy surfaces. As a demonstration, we present simulation results on the high dimensional conformational landscapes of the alanine tripeptide in vacuo, tetra-N-methylglycine (tetra-sarcosine) peptoid in implicit solvent, and the Trp-cage mini protein in explicit water.
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Affiliation(s)
- Shitanshu Bajpai
- Department of Chemistry, Indian Institute of Technology Kanpur (IITK), Kanpur, India
| | - Brian K Petkov
- Department of Chemistry, New York University (NYU), New York, New York, USA
| | - Muchen Tong
- Department of Chemistry, New York University (NYU), New York, New York, USA
| | - Charlles R A Abreu
- Chemical Engineering Department, Escola de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Nisanth N Nair
- Department of Chemistry, Indian Institute of Technology Kanpur (IITK), Kanpur, India
| | - Mark E Tuckerman
- Department of Chemistry, New York University (NYU), New York, New York, USA
- Courant Institute of Mathematical Sciences, New York University (NYU), New York, New York, USA
- NYU-ECNU Center for Computational Chemistry at NYU Shanghai, Shanghai, China
- Simons Center for Computational Physical Chemistry, New York University, New York, New York, USA
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4
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Maruyama Y, Igarashi R, Ushiku Y, Mitsutake A. Analysis of Protein Folding Simulation with Moving Root Mean Square Deviation. J Chem Inf Model 2023; 63:1529-1541. [PMID: 36821519 PMCID: PMC10015464 DOI: 10.1021/acs.jcim.2c01444] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
We apply moving root-mean-square deviation (mRMSD), which does not require a reference structure, as a method for analyzing protein dynamics. This method can be used to calculate the root-mean-square deviation (RMSD) of structure between two specified time points and to analyze protein dynamics behavior through time series analysis. We applied this method to the Trp-cage trajectory calculated by the Anton supercomputer and found that it shows regions of stable states as well as the conventional RMSD. In addition, we extracted a characteristic structure in which the side chains of Asp1 and Arg16 form hydrogen bonds near the most stable structure of the Trp-cage. We also determined that ≥20 ns is an appropriate time interval to investigate protein dynamics using mRMSD. Applying this method to NuG2 protein, we found that mRMSD can be used to detect regions of metastable states in addition to the stable state. This method can be applied to molecular dynamics simulations of proteins whose stable structures are unknown.
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Affiliation(s)
- Yutaka Maruyama
- OMRON SINIC X Corporation, Tokyo 113-0033, Japan.,Department of Physics, School of Science and Technology, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki-shi, Kanagawa 214-8571, Japan
| | - Ryo Igarashi
- OMRON SINIC X Corporation, Tokyo 113-0033, Japan
| | | | - Ayori Mitsutake
- Department of Physics, School of Science and Technology, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki-shi, Kanagawa 214-8571, Japan
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5
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Kapakayala AB, Nair NN. Boosting the conformational sampling by combining replica exchange with solute tempering and well-sliced metadynamics. J Comput Chem 2021; 42:2233-2240. [PMID: 34585768 DOI: 10.1002/jcc.26752] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 08/30/2021] [Accepted: 09/12/2021] [Indexed: 01/22/2023]
Abstract
Methods that combine collective variable (CV) based enhanced sampling and global tempering approaches are used in speeding-up the conformational sampling and free energy calculation of large and soft systems with a plethora of energy minima. In this paper, a new method of this kind is proposed in which the well-sliced metadynamics approach (WSMTD) is united with replica exchange with solute tempering (REST2) method. WSMTD employs a divide-and-conquer strategy wherein high-dimensional slices of a free energy surface are independently sampled and combined. The method enables one to accomplish a controlled exploration of the CV-space with a restraining bias as in umbrella sampling, and enhance-sampling of one or more orthogonal CVs using a metadynamics like bias. The new hybrid method proposed here enables boosting the sampling of more slow degrees of freedom in WSMTD simulations, without the need to specify associated CVs, through a replica exchange scheme within the framework of REST2. The high-dimensional slices of the probability distributions of CVs computed from the united WSMTD and REST2 simulations are subsequently combined using the weighted histogram analysis method to obtain the free energy surface. We show that the new method proposed here is accurate, improves the conformational sampling, and achieves quick convergence in free energy estimates. We demonstrate this by computing the conformational free energy landscapes of solvated alanine tripeptide and Trp-cage mini protein in explicit water.
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Affiliation(s)
- Anji Babu Kapakayala
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, India.,School of Pharmacy and Biomedical Sciences, Curtin University, Perth, Australia
| | - Nisanth N Nair
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, India
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6
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Pal S, Roy R, Paul S. Potential of a Natural Deep Eutectic Solvent, Glyceline, in the Thermal Stability of the Trp-Cage Mini-protein. J Phys Chem B 2020; 124:7598-7610. [DOI: 10.1021/acs.jpcb.0c03501] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Saikat Pal
- Department of Chemistry, Indian Institute of Technology, Guwahati, Assam 781039, India
| | - Rituparna Roy
- Department of Chemistry, Indian Institute of Technology, Guwahati, Assam 781039, India
| | - Sandip Paul
- Department of Chemistry, Indian Institute of Technology, Guwahati, Assam 781039, India
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7
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Especial J, Nunes A, Rey A, Faísca PF. Hydrophobic confinement modulates thermal stability and assists knotting in the folding of tangled proteins. Phys Chem Chem Phys 2019; 21:11764-11775. [PMID: 31114834 DOI: 10.1039/c9cp01701a] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
There is growing support for the idea that the in vivo folding process of knotted proteins is assisted by chaperonins, but the mechanism of chaperonin assisted folding remains elusive. Here, we conduct extensive Monte Carlo simulations of lattice and off-lattice models to explore the effects of confinement and hydrophobic intermolecular interactions with the chaperonin cage in the folding and knotting processes. We find that moderate to high protein-cavity interactions (which are likely to be established in the beginning of the chaperonin working cycle) cause an energetic destabilization of the protein that overcomes the entropic stabilization driven by excluded volume, and leads to a decrease of the melting temperature relative to bulk conditions. Moreover, mild-to-moderate hydrophobic interactions with the cavity (which would be established later in the cycle) lead to a significant enhancement of knotting probability in relation to bulk conditions while simultaneously moderating the effect of steric confinement in the enhancement of thermal stability. Our results thus indicate that the chaperonin may be able to assist knotting without simultaneously thermally stabilizing potential misfolded states to a point that would hamper productive folding thus compromising its functional role.
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Affiliation(s)
- João Especial
- Departamento de Física, Universidade de Lisboa, Campo Grande, Ed. C8, 1749-016 Lisboa, Portugal.
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8
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Cai Z, Zhang Y. Hydrophobicity-driven unfolding of Trp-cage encapsulated between graphene sheets. Colloids Surf B Biointerfaces 2018; 168:103-108. [PMID: 29627125 DOI: 10.1016/j.colsurfb.2018.03.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 03/23/2018] [Accepted: 03/24/2018] [Indexed: 11/17/2022]
Abstract
Understanding the interaction between proteins and graphene not only helps elucidate the behaviors of proteins in confined geometries, but is also imperative to the development of a plethora of graphene-based biotechnologies, such as the graphene liquid cell transmission electron microscopy. To discuss the overall geometrical-thermal effects on proteins, we performed molecular dynamics simulations of hydrated Trp-cage miniprotein sandwiched between two graphene sheets and in the bulk environment at the temperatures below and above its unfolding temperature. The structural fluctuations of Trp-cage were characterized using the backbone root mean square displacement and the radius of gyration, from which the free energy landscape of Trp-cage was further constructed. We observed that at both temperatures the confined protein became adsorbed to the graphene surfaces and exhibited unfolded structures. Residue-specific analyses clearly showed the preference for the graphene to interact with the hydrophobic regions of Trp-cage. These results suggested that the conformation space accessible to the protein results from the competition between the thermodynamic driving forces and the geometrical restraints. While confinement usually tends to restrict the conformation of proteins by volume exclusion, it may also induce the unfolding of proteins by hydrophobic interactions.
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Affiliation(s)
- Zhikun Cai
- Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Yang Zhang
- Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
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9
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Cheng C, Wu J, Liu G, Shi S, Chen T. Effects of Non-native Interactions on Frustrated Proteins Folding under Confinement. J Phys Chem B 2018; 122:7654-7667. [DOI: 10.1021/acs.jpcb.8b04147] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Chenqian Cheng
- Key Laboratory of Synthetic and Natural Functional Molecular Chemistry of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi’an 710127, P. R. China
| | - Jing Wu
- Key Laboratory of Synthetic and Natural Functional Molecular Chemistry of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi’an 710127, P. R. China
| | - Gaoyuan Liu
- Key Laboratory of Synthetic and Natural Functional Molecular Chemistry of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi’an 710127, P. R. China
| | - Suqing Shi
- Key Laboratory of Synthetic and Natural Functional Molecular Chemistry of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi’an 710127, P. R. China
| | - Tao Chen
- Key Laboratory of Synthetic and Natural Functional Molecular Chemistry of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi’an 710127, P. R. China
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10
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Van Meervelt V, Soskine M, Singh S, Schuurman-Wolters GK, Wijma HJ, Poolman B, Maglia G. Real-Time Conformational Changes and Controlled Orientation of Native Proteins Inside a Protein Nanoreactor. J Am Chem Soc 2017; 139:18640-18646. [PMID: 29206456 PMCID: PMC6150693 DOI: 10.1021/jacs.7b10106] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
![]()
Protein conformations play crucial
roles in most, if not all, biological
processes. Here we show that the current carried through a nanopore
by ions allows monitoring conformational changes of single and native
substrate-binding domains (SBD) of an ATP-Binding Cassette importer
in real-time. Comparison with single-molecule Förster Resonance
Energy Transfer and ensemble measurements revealed that proteins trapped
inside the nanopore have bulk-like properties. Two ligand-free and
two ligand-bound conformations of SBD proteins were inferred and their
kinetic constants were determined. Remarkably, internalized proteins
aligned with the applied voltage bias, and their orientation could
be controlled by the addition of a single charge to the protein surface.
Nanopores can thus be used to immobilize proteins on a surface with
a specific orientation, and will be employed as nanoreactors for single-molecule
studies of native proteins. Moreover, nanopores with internal protein
adaptors might find further practical applications in multianalyte
sensing devices.
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Affiliation(s)
- Veerle Van Meervelt
- Department of Chemistry, University of Leuven , Leuven B-3001, Belgium.,Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen , Groningen 9747 AG, The Netherlands
| | - Misha Soskine
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen , Groningen 9747 AG, The Netherlands
| | - Shubham Singh
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen , Groningen 9747 AG, The Netherlands
| | - Gea K Schuurman-Wolters
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen , Groningen 9747 AG, The Netherlands
| | - Hein J Wijma
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen , Groningen 9747 AG, The Netherlands
| | - Bert Poolman
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen , Groningen 9747 AG, The Netherlands
| | - Giovanni Maglia
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen , Groningen 9747 AG, The Netherlands
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11
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Andryushchenko VA, Chekmarev SF. Temperature evolution of Trp-cage folding pathways: An analysis by dividing the probability flux field into stream tubes. J Biol Phys 2017; 43:565-583. [PMID: 28983809 DOI: 10.1007/s10867-017-9470-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 09/01/2017] [Indexed: 11/25/2022] Open
Abstract
Owing to its small size and very fast folding rate, the Trp-cage miniprotein has become a benchmark system to study protein folding. Two folding pathways were found to be characteristic of this protein: pathway I, in which the hydrophobic collapse precedes the formation of α-helix, and pathway II, in which the events occur in the reverse order. At the same time, the relative contribution of these pathways at different temperatures as well as the nature of transition from one pathway to the other remain unclear. To gain insight into this issue, we employ a recently proposed hydrodynamic description of protein folding, in which the process of folding is considered as a motion of a "folding fluid" (Chekmarev et al., Phys. Rev. Lett. 100(1), 018107 2008). Using molecular dynamics simulations, we determine the field of probability fluxes of transitions in a space of collective variables and divide it into stream tubes. Each tube contains a definite fraction of the total folding flow and can be associated with a certain pathway. Specifically, three temperatures were considered, T = 285K, T = 315K, and T = 325K. We have found that as the temperature increases, the contribution of pathway I, which is approximately 90% of the total folding flow at T = 285K, decreases to approximately 10% at T = 325K, i.e., pathway II becomes dominant. At T = 315K, both pathways contribute approximately equally. All these temperatures are found below the calculated melting point, which suggests that the Trp-cage folding mechanism is determined by kinetic factors rather than thermodynamics.
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Affiliation(s)
- Vladimir A Andryushchenko
- Institute of Thermophysics, SB RAS, 630090, Novosibirsk, Russia
- Department of Physics, Novosibirsk State University, 630090, Novosibirsk, Russia
| | - Sergei F Chekmarev
- Institute of Thermophysics, SB RAS, 630090, Novosibirsk, Russia.
- Department of Physics, Novosibirsk State University, 630090, Novosibirsk, Russia.
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12
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Sprenger KG, Pfaendtner J. Strong Electrostatic Interactions Lead to Entropically Favorable Binding of Peptides to Charged Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:5690-5701. [PMID: 27181161 DOI: 10.1021/acs.langmuir.6b01296] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Thermodynamic analyses can provide key insights into the origins of protein self-assembly on surfaces, protein function, and protein stability. However, obtaining quantitative measurements of thermodynamic observables from unbiased classical simulations of peptide or protein adsorption is challenging because of sampling limitations brought on by strong biomolecule/surface binding forces as well as time scale limitations. We used the parallel tempering metadynamics in the well-tempered ensemble (PTMetaD-WTE) enhanced sampling method to study the adsorption behavior and thermodynamics of several explicitly solvated model peptide adsorption systems, providing new molecular-level insight into the biomolecule adsorption process. Specifically studied were peptides LKα14 and LKβ15 and trpcage miniprotein adsorbing onto a charged, hydrophilic self-assembled monolayer surface functionalized with a carboxylic acid/carboxylate headgroup and a neutral, hydrophobic methyl-terminated self-assembled monolayer surface. Binding free energies were calculated as a function of temperature for each system and decomposed into their respective energetic and entropic contributions. We investigated how specific interfacial features such as peptide/surface electrostatic interactions and surface-bound ion content affect the thermodynamic landscape of adsorption and lead to differences in surface-bound conformations of the peptides. Results show that upon adsorption to the charged surface, configurational entropy gains of the released solvent molecules dominate the configurational entropy losses of the bound peptide. This behavior leads to an apparent increase in overall system entropy upon binding and therefore to the surprising and seemingly nonphysical result of an apparent increased binding free energy at elevated temperatures. Opposite effects and conclusions are found for the neutral surface. Additional simulations demonstrate that by adjusting the ionic strength of the solution, results that show the expected physical behavior, i.e., peptide binding strength that decreases with increasing temperature or is independent of temperature altogether, can be recovered on the charged surface. On the basis of this analysis, an overall free energy for the entire thermodynamic cycle for peptide adsorption on charged surfaces is constructed and validated with independent simulations.
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Affiliation(s)
- K G Sprenger
- Department of Chemical Engineering, University of Washington , Seattle, Washington 98195-1750, United States
| | - Jim Pfaendtner
- Department of Chemical Engineering, University of Washington , Seattle, Washington 98195-1750, United States
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13
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Levine ZA, DeNardis NI, Vernier PT. Phospholipid and Hydrocarbon Interactions with a Charged Electrode Interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:2808-2819. [PMID: 26927605 DOI: 10.1021/acs.langmuir.5b04090] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Using a combination of molecular dynamics simulations and experiments we examined the interactions of alkanes and phospholipids at charged interfaces in order to understand how interfacial charge densities affect the association of these two representative molecules with electrodes. Consistent with theory and experiment, these model systems reveal interfacial associations mediated through a combination of Coulombic and van der Waals forces. van der Waals forces, in particular, mediate rapid binding of decane to neutral electrodes. No decane binding was observed at high surface charge densities because of interfacial water polarization, which screens hydrophobic attractions. The positively charged choline moiety of the phospholipid palmitoyloleoylphosphatidylcholine (POPC) is primarily responsible for POPC attraction by a moderately negatively charged electrode. The hydrocarbon tails of POPC interact with the hydrophobic electrode interface similarly to decane. Previously reported electrochemical results confirm these findings by demonstrating bipolar displacement currents from PC vesicles adhering to moderately negatively charged interfaces, originating from the choline interactions observed in simulations. At more negatively charged interfaces, choline-to-surface binding was stronger. In both simulations and experiments the maximal interaction of anionic PS occurs with a positively charged interface, provided that the electrostatic forces outweigh local Lennard-Jones interactions. Direct comparisons between the binding affinities measured in experiments and those obtained in simulations reveal previously unobserved atomic interactions that facilitate lipid vesicle adhesion to charged interfaces. Moreover, the implementation of a charged interface in molecular dynamics simulations provides an alternative method for the generation of large electric fields across phospholipid bilayers, especially for systems with periodic boundary conditions, and may be useful for simulations of membrane electropermeabilization.
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Affiliation(s)
| | - Nadica Ivošević DeNardis
- Division for Marine and Environmental Research, Ruđer Bošković Institute , 10000 Zagreb, Croatia
| | - P Thomas Vernier
- Frank Reidy Research Center for Bioelectrics, Old Dominion University , Norfolk, Virginia 23508, United States
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14
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Zhang H, Lv Y, Tan T, van der Spoel D. Atomistic Simulation of Protein Encapsulation in Metal–Organic Frameworks. J Phys Chem B 2016; 120:477-84. [DOI: 10.1021/acs.jpcb.5b10437] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Haiyang Zhang
- Beijing
Key Lab of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Box 53, 100029 Beijing, China
- Department
of Biological Science and Engineering, School of Chemistry and Biological
Engineering, University of Science and Technology Beijing, 100083 Beijing, China
| | - Yongqin Lv
- Beijing
Key Lab of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Box 53, 100029 Beijing, China
| | - Tianwei Tan
- Beijing
Key Lab of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Box 53, 100029 Beijing, China
| | - David van der Spoel
- Uppsala
Center for Computational Chemistry, Science for Life Laboratory, Department
of Cell and Molecular Biology, Uppsala University, Husargatan 3, Box
596, SE-75124 Uppsala, Sweden
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15
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Gupta M, Nayar D, Chakravarty C, Bandyopadhyay S. Comparison of hydration behavior and conformational preferences of the Trp-cage mini-protein in different rigid-body water models. Phys Chem Chem Phys 2016; 18:32796-32813. [DOI: 10.1039/c6cp04634g] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Trp-cage unfolds at different temperatures in different water models revealing the sensitivity of conformational order metrics to the choice of water models.
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Affiliation(s)
- Madhulika Gupta
- Department of Chemistry
- Indian Institute of Technology-Delhi
- New Delhi 110016
- India
| | - Divya Nayar
- Department of Chemistry
- Indian Institute of Technology-Delhi
- New Delhi 110016
- India
| | | | - Sanjoy Bandyopadhyay
- Molecular Modeling Laboratory
- Department of Chemistry
- Indian Institute of Technology
- Kharagpur 721302
- India
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16
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A hydrodynamic view of the first-passage folding of Trp-cage miniprotein. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2015; 45:229-43. [PMID: 26559408 DOI: 10.1007/s00249-015-1089-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 09/27/2015] [Accepted: 10/09/2015] [Indexed: 12/11/2022]
Abstract
We study folding of Trp-cage miniprotein in the conditions when the native state of the protein is stable and unfolding events are improbable, which corresponds to physiological conditions. Using molecular dynamics simulations with an implicit solvent model, an ensemble of folding trajectories from unfolded (practically extended) states of the protein to the native state was generated. To get insight into the folding kinetics, the free energy surface and kinetic network projected on this surface were constructed. This, "conventional" analysis of the folding reaction was followed by a recently proposed hydrodynamic description of protein folding (Chekmarev et al. in Phys Rev Lett 100(1):018107, 2008), in which the process of the first-passage folding is viewed as a stationary flow of a folding "fluid" from the unfolded to native state. This approach is conceptually different from the previously used approaches and thus allows an alternative view of the folding dynamics and kinetics of Trp-cage, the conclusions about which are very diverse. In agreement with most previous studies, we observed two characteristic folding pathways: in one pathway (I), the collapse of the hydrophobic core precedes the formation of the [Formula: see text]-helix, and in the other pathway (II), these events occur in the reverse order. We found that although pathway II is complicated by a repeated partial protein unfolding, it contributes to the total folding flow as little as ≈10%, so that the folding kinetics remain essentially single-exponential.
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17
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Zang T, Yu L, Zhang C, Ma J. Parallel continuous simulated tempering and its applications in large-scale molecular simulations. J Chem Phys 2015; 141:044113. [PMID: 25084887 DOI: 10.1063/1.4890038] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
In this paper, we introduce a parallel continuous simulated tempering (PCST) method for enhanced sampling in studying large complex systems. It mainly inherits the continuous simulated tempering (CST) method in our previous studies [C. Zhang and J. Ma, J. Chem. Phys. 130, 194112 (2009); C. Zhang and J. Ma, J. Chem. Phys. 132, 244101 (2010)], while adopts the spirit of parallel tempering (PT), or replica exchange method, by employing multiple copies with different temperature distributions. Differing from conventional PT methods, despite the large stride of total temperature range, the PCST method requires very few copies of simulations, typically 2-3 copies, yet it is still capable of maintaining a high rate of exchange between neighboring copies. Furthermore, in PCST method, the size of the system does not dramatically affect the number of copy needed because the exchange rate is independent of total potential energy, thus providing an enormous advantage over conventional PT methods in studying very large systems. The sampling efficiency of PCST was tested in two-dimensional Ising model, Lennard-Jones liquid and all-atom folding simulation of a small globular protein trp-cage in explicit solvent. The results demonstrate that the PCST method significantly improves sampling efficiency compared with other methods and it is particularly effective in simulating systems with long relaxation time or correlation time. We expect the PCST method to be a good alternative to parallel tempering methods in simulating large systems such as phase transition and dynamics of macromolecules in explicit solvent.
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Affiliation(s)
- Tianwu Zang
- Applied Physics Program and Department of Bioengineering, Rice University, Houston, Texas 77005, USA
| | - Linglin Yu
- Applied Physics Program and Department of Bioengineering, Rice University, Houston, Texas 77005, USA
| | - Chong Zhang
- Applied Physics Program and Department of Bioengineering, Rice University, Houston, Texas 77005, USA
| | - Jianpeng Ma
- Applied Physics Program and Department of Bioengineering, Rice University, Houston, Texas 77005, USA
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18
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Affiliation(s)
- Zachary A. Levine
- Department
of Physics, University of California Santa Barbara, Santa Barbara, California 93106, United States
- Department
of Chemistry and Biochemistry, University of California Santa Barbara, Santa
Barbara, California 93106, United States
| | - Sean A. Fischer
- Department
of Chemical Engineering, University of Washington, Seattle, Washington 98105, United States
| | - Joan-Emma Shea
- Department
of Physics, University of California Santa Barbara, Santa Barbara, California 93106, United States
- Department
of Chemistry and Biochemistry, University of California Santa Barbara, Santa
Barbara, California 93106, United States
| | - Jim Pfaendtner
- Department
of Chemical Engineering, University of Washington, Seattle, Washington 98105, United States
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19
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English CA, García AE. Charged Termini on the Trp-Cage Roughen the Folding Energy Landscape. J Phys Chem B 2015; 119:7874-81. [DOI: 10.1021/acs.jpcb.5b02040] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Charles A. English
- Department of Physics and Astronomy and The Center for
Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Angel E. García
- Department of Physics and Astronomy and The Center for
Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
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20
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Yu Y, Wang J, Liu J, Ling D, Xia J. Functional assembly of protein fragments induced by spatial confinement. PLoS One 2015; 10:e0122101. [PMID: 25875003 PMCID: PMC4398348 DOI: 10.1371/journal.pone.0122101] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 02/17/2015] [Indexed: 02/05/2023] Open
Abstract
Natural proteins are often confined within their local microenvironments, such as three-dimensional confinement in organelles or two-dimensional confinement in lipid rafts on cytoplasmic membrane. Spatial confinement restricts proteins' entropic freedom, forces their lateral interaction, and induces new properties that the same proteins lack at the soluble state. So far, the phenomenon of environment-induced protein functional alteration still lacks a full illustration. We demonstrate here that engineered protein fragments, although being non-functional in solution, can be re-assembled within the nanometer space to give the full activity of the whole protein. Specific interaction between hexahistidine-tag (His-tag) and NiO surface immobilizes protein fragments on NiO nanoparticles to form a self-assembled protein "corona" on the particles inside the nanopores of mesoporous silica. Site-specific assembly forces a shoulder-by-shoulder orientation and promotes fragment-fragment interaction; this interaction together with spatial confinement of the mesopores results in functional re-assembly of the protein half fragments. To our surprise, a single half fragment of luciferase (non-catalytic in solution) exhibited luciferase activity when immobilized on NiO in the mesopores, in the absence of the complimentary half. This shows for the first time that spatial confinement can induce the folding of a half fragment, reconstitute the enzyme active site, and re-gain the catalytic capability of the whole protein. Our work thereby highlights the under-documented notion that aside from the chemical composition such as primary sequence, physical environment of a protein also determines its function.
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Affiliation(s)
- Yongsheng Yu
- Department of Chemistry, Center of Novel Biomaterials, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Jianpeng Wang
- Department of Chemistry, Center of Novel Biomaterials, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Jiahui Liu
- Department of Chemistry, Center of Novel Biomaterials, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Daishun Ling
- Institute of Pharmaceutics, College of Pharmaceutical Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, China
| | - Jiang Xia
- Department of Chemistry, Center of Novel Biomaterials, The Chinese University of Hong Kong, Shatin, Hong Kong, China
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21
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Ni R, Kleijn JM, Abeln S, Cohen Stuart MA, Bolhuis PG. Competition between surface adsorption and folding of fibril-forming polypeptides. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:022711. [PMID: 25768535 DOI: 10.1103/physreve.91.022711] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Indexed: 06/04/2023]
Abstract
Self-assembly of polypeptides into fibrillar structures can be initiated by planar surfaces that interact favorably with certain residues. Using a coarse-grained model, we systematically studied the folding and adsorption behavior of a β-roll forming polypeptide. We find that there are two different folding pathways depending on the temperature: (i) at low temperature, the polypeptide folds in solution into a β-roll before adsorbing onto the attractive surface; (ii) at higher temperature, the polypeptide first adsorbs in a disordered state and folds while on the surface. The folding temperature increases with increasing attraction as the folded β-roll is stabilized by the surface. Surprisingly, further increasing the attraction lowers the folding temperature again, as strong attraction also stabilizes the adsorbed disordered state, which competes with folding of the polypeptide. Our results suggest that to enhance the folding, one should use a weakly attractive surface. They also explain the recent experimental observation of the nonmonotonic effect of charge on the fibril formation on an oppositely charged surface [C. Charbonneau et al., ACS Nano 8, 2328 (2014)].
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Affiliation(s)
- Ran Ni
- Van 't Hoff Institute for Molecular Sciences, Universiteit van Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
- Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, 6703 HB Wageningen, The Netherlands
| | - J Mieke Kleijn
- Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, 6703 HB Wageningen, The Netherlands
| | - Sanne Abeln
- Centre for Integrative Bioinformatics (IBIVU), Vrije Universiteit, De Boelelaan 1081A, 1081 HV Amsterdam, The Netherlands
| | - Martien A Cohen Stuart
- Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, 6703 HB Wageningen, The Netherlands
| | - Peter G Bolhuis
- Van 't Hoff Institute for Molecular Sciences, Universiteit van Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
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22
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Peter EK, Agarwal M, Kim B, Pivkin IV, Shea JE. How water layers on graphene affect folding and adsorption of TrpZip2. J Chem Phys 2014; 141:22D511. [DOI: 10.1063/1.4896984] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Emanuel K. Peter
- Insitute of Computational Science, Faculty of Informatics, University of Lugano, Switzerland
- Department of Chemistry and Biochemistry and Department of Physics, University of California Santa Barbara, California 93106, USA
| | - Mrigya Agarwal
- Insitute of Computational Science, Faculty of Informatics, University of Lugano, Switzerland
| | - BongKeun Kim
- Department of Chemistry and Biochemistry and Department of Physics, University of California Santa Barbara, California 93106, USA
| | - Igor V. Pivkin
- Insitute of Computational Science, Faculty of Informatics, University of Lugano, Switzerland
| | - Joan-Emma Shea
- Department of Chemistry and Biochemistry and Department of Physics, University of California Santa Barbara, California 93106, USA
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23
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Vaitheeswaran S, Thirumalai D. Entropy and enthalpy of interaction between amino acid side chains in nanopores. J Chem Phys 2014; 141:22D523. [PMID: 25494794 DOI: 10.1063/1.4901204] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Understanding the stabilities of proteins in nanopores requires a quantitative description of confinement induced interactions between amino acid side chains. We use molecular dynamics simulations to study the nature of interactions between the side chain pairs ALA-PHE, SER-ASN, and LYS-GLU in bulk water and in water-filled nanopores. The temperature dependence of the bulk solvent potentials of mean force and the interaction free energies in cylindrical and spherical nanopores is used to identify the corresponding entropic and enthalpic components. The entropically stabilized hydrophobic interaction between ALA and PHE in bulk water is enthalpically dominated upon confinement depending on the relative orientations between the side chains. In the case of SER-ASN, hydrogen bonded configurations that are similar in bulk water are thermodynamically distinct in a cylindrical pore, thus making rotamer distributions different from those in the bulk. Remarkably, salt bridge formation between LYS-GLU is stabilized by entropy in contrast to the bulk. Implications of our findings for confinement-induced alterations in protein stability are briefly outlined.
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Affiliation(s)
- S Vaitheeswaran
- Biophysics Program, Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742, USA
| | - D Thirumalai
- Biophysics Program, Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742, USA
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24
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Combined effect of confinement and affinity of crowded environment on conformation switching of adenylate kinase. J Mol Model 2014; 20:2530. [DOI: 10.1007/s00894-014-2530-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2014] [Accepted: 11/12/2014] [Indexed: 01/25/2023]
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25
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Du W, Bolhuis PG. Sampling the equilibrium kinetic network of Trp-cage in explicit solvent. J Chem Phys 2014; 140:195102. [PMID: 24852564 DOI: 10.1063/1.4874299] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We employed the single replica multiple state transition interface sampling (MSTIS) approach to sample the kinetic (un)folding network of Trp-cage mini-protein in explicit water. Cluster analysis yielded 14 important metastable states in the network. The MSTIS simulation thus resulted in a full 14 × 14 rate matrix. Analysis of the kinetic rate matrix indicates the presence of a near native intermediate state characterized by a fully formed alpha helix, a slightly disordered proline tail, a broken salt-bridge, and a rotated arginine residue. This intermediate was also found in recent IR experiments. Moreover, the predicted rate constants and timescales are in agreement with previous experiments and simulations.
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Affiliation(s)
- Weina Du
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, PO Box 94157, 1090 GD Amsterdam, The Netherlands
| | - Peter G Bolhuis
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, PO Box 94157, 1090 GD Amsterdam, The Netherlands
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26
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Zeiler RN, Bolhuis PG. Exposure of thiol groups in the heat-induced denaturation of β-lactoglobulin. MOLECULAR SIMULATION 2014. [DOI: 10.1080/08927022.2014.926547] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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27
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Singh P, Sarkar SK, Bandyopadhyay P. Wang-Landau density of states based study of the folding-unfolding transition in the mini-protein Trp-cage (TC5b). J Chem Phys 2014; 141:015103. [DOI: 10.1063/1.4885726] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Affiliation(s)
- Priya Singh
- School of Physical Sciences, Jawaharlal Nehru University, New Delhi - 110 067, India
| | - Subir K. Sarkar
- School of Physical Sciences, Jawaharlal Nehru University, New Delhi - 110 067, India
| | - Pradipta Bandyopadhyay
- School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi - 110 067, India
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28
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Mou L, Jia X, Gao Y, Li Y, Zhang JZH, Mei Y. Folding simulation of Trp-cage utilizing a new AMBER compatible force field with coupled main chain torsions. JOURNAL OF THEORETICAL & COMPUTATIONAL CHEMISTRY 2014. [DOI: 10.1142/s0219633614500266] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A newly developed AMBER compatible force field with coupled backbone torsion potential terms (AMBER032D) is utilized in a folding simulation of a mini-protein Trp-cage. Through replica exchange and direct molecular dynamics (MD) simulations, a multi-step folding mechanism with a synergetic folding of the hydrophobic core (HPC) and the α-helix in the final stage is suggested. The native structure has the lowest free energy and the melting temperature predicted from the specific heat capacity Cvis only 12 K higher than the experimental measurement. This study, together with our previous study, shows that AMBER032Dis an accurate force field that can be used for protein folding simulations.
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Affiliation(s)
- Lirong Mou
- Institute for Advanced Interdisciplinary Research, East China Normal University, Shanghai 200062, P. R. China
| | - Xiangyu Jia
- Center for Laser and Computational Biophysics, State Key Laboratory of Precision Spectroscopy and Department of Physics, Institute of Theoretical and Computational Science, East China Normal University, Shanghai 200062, P. R. China
| | - Ya Gao
- Center for Laser and Computational Biophysics, State Key Laboratory of Precision Spectroscopy and Department of Physics, Institute of Theoretical and Computational Science, East China Normal University, Shanghai 200062, P. R. China
| | - Yongxiu Li
- Center for Laser and Computational Biophysics, State Key Laboratory of Precision Spectroscopy and Department of Physics, Institute of Theoretical and Computational Science, East China Normal University, Shanghai 200062, P. R. China
| | - John Z. H. Zhang
- Center for Laser and Computational Biophysics, State Key Laboratory of Precision Spectroscopy and Department of Physics, Institute of Theoretical and Computational Science, East China Normal University, Shanghai 200062, P. R. China
- NYU-ECNU Center for Computational Chemistry at NYU Shanghai, Shanghai 200062, P. R. China
| | - Ye Mei
- Center for Laser and Computational Biophysics, State Key Laboratory of Precision Spectroscopy and Department of Physics, Institute of Theoretical and Computational Science, East China Normal University, Shanghai 200062, P. R. China
- NYU-ECNU Center for Computational Chemistry at NYU Shanghai, Shanghai 200062, P. R. China
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29
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Sirur A, Knott M, Best RB. Effect of interactions with the chaperonin cavity on protein folding and misfolding. Phys Chem Chem Phys 2014; 16:6358-66. [PMID: 24077053 PMCID: PMC4577569 DOI: 10.1039/c3cp52872c] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Recent experimental and computational results have suggested that attractive interactions between a chaperonin and an enclosed substrate can have an important effect on the protein folding rate: it appears that folding may even be slower inside the cavity than under unconfined conditions, in contrast to what we would expect from excluded volume effects on the unfolded state. Here we examine systematically the dependence of the protein stability and folding rate on the strength of such attractive interactions between the chaperonin and substrate, by using molecular simulations of model protein systems in an idealised attractive cavity. Interestingly, we find a maximum in stability, and a rate which indeed slows down at high attraction strengths. We have developed a simple phenomenological model which can explain the variations in folding rate and stability due to differing effects on the free energies of the unfolded state, folded state, and transition state; changes in the diffusion coefficient along the folding coordinate are relatively small, at least for our simplified model. In order to investigate a possible role for these attractive interactions in folding, we have studied a recently developed model for misfolding in multidomain proteins. We find that, while encapsulation in repulsive cavities greatly increases the fraction of misfolded protein, sufficiently strong attractive protein-cavity interactions can strongly reduce the fraction of proteins reaching misfolded traps.
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Affiliation(s)
- Anshul Sirur
- Cambridge University, Department of Chemistry, Lensfield Road Cambridge CB2 1EW, United Kingdom
| | - Michael Knott
- Cambridge University, Department of Chemistry, Lensfield Road Cambridge CB2 1EW, United Kingdom
| | - Robert B. Best
- Cambridge University, Department of Chemistry, Lensfield Road Cambridge CB2 1EW, United Kingdom
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0520, United States
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30
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Piana S, Klepeis JL, Shaw DE. Assessing the accuracy of physical models used in protein-folding simulations: quantitative evidence from long molecular dynamics simulations. Curr Opin Struct Biol 2014; 24:98-105. [DOI: 10.1016/j.sbi.2013.12.006] [Citation(s) in RCA: 294] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 12/19/2013] [Accepted: 12/20/2013] [Indexed: 01/15/2023]
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31
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Meuzelaar H, Marino KA, Huerta-Viga A, Panman MR, Smeenk LEJ, Kettelarij AJ, van Maarseveen JH, Timmerman P, Bolhuis PG, Woutersen S. Folding dynamics of the Trp-cage miniprotein: evidence for a native-like intermediate from combined time-resolved vibrational spectroscopy and molecular dynamics simulations. J Phys Chem B 2013; 117:11490-501. [PMID: 24050152 DOI: 10.1021/jp404714c] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Trp-cage is a synthetic 20-residue miniprotein which folds rapidly and spontaneously to a well-defined globular structure more typical of larger proteins. Due to its small size and fast folding, it is an ideal model system for experimental and theoretical investigations of protein folding mechanisms. However, Trp-cage's exact folding mechanism is still a matter of debate. Here we investigate Trp-cage's relaxation dynamics in the amide I' spectral region (1530-1700 cm(-1)) using time-resolved infrared spectroscopy. Residue-specific information was obtained by incorporating an isotopic label ((13)C═(18)O) into the amide carbonyl group of residue Gly11, thereby spectrally isolating an individual 310-helical residue. The folding-unfolding equilibrium is perturbed using a nanosecond temperature-jump (T-jump), and the subsequent re-equilibration is probed by observing the time-dependent vibrational response in the amide I' region. We observe bimodal relaxation kinetics with time constants of 100 ± 10 and 770 ± 40 ns at 322 K, suggesting that the folding involves an intermediate state, the character of which can be determined from the time- and frequency-resolved data. We find that the relaxation dynamics close to the melting temperature involve fast fluctuations in the polyproline II region, whereas the slower process can be attributed to conformational rearrangements due to the global (un)folding transition of the protein. Combined analysis of our T-jump data and molecular dynamics simulations indicates that the formation of a well-defined α-helix precedes the rapid formation of the hydrophobic cage structure, implying a native-like folding intermediate, that mainly differs from the folded conformation in the orientation of the C-terminal polyproline II helix relative to the N-terminal part of the backbone. We find that the main free-energy barrier is positioned between the folding intermediate and the unfolded state ensemble, and that it involves the formation of the α-helix, the 310-helix, and the Asp9-Arg16 salt bridge. Our results suggest that at low temperature (T ≪ Tm) a folding path via formation of α-helical contacts followed by hydrophobic clustering becomes more important.
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Affiliation(s)
- Heleen Meuzelaar
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam , Science Park 904, 1098 XH Amsterdam, The Netherlands
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32
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Mashaghi A, Kramer G, Lamb DC, Mayer MP, Tans SJ. Chaperone Action at the Single-Molecule Level. Chem Rev 2013; 114:660-76. [DOI: 10.1021/cr400326k] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Alireza Mashaghi
- AMOLF Institute, Science Park
104, 1098 XG Amsterdam, The Netherlands
| | - Günter Kramer
- Zentrum
für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Allianz, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Don C. Lamb
- Physical
Chemistry, Department of Chemistry, Munich Center for Integrated Protein
Science (CiPSM) and Center for Nanoscience, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, Gerhard-Ertl-Building, 81377 Munich, Germany
| | - Matthias P. Mayer
- Zentrum
für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Allianz, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Sander J. Tans
- AMOLF Institute, Science Park
104, 1098 XG Amsterdam, The Netherlands
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33
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Sirur A, Best RB. Effects of interactions with the GroEL cavity on protein folding rates. Biophys J 2013; 104:1098-106. [PMID: 23473493 DOI: 10.1016/j.bpj.2013.01.034] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 01/09/2013] [Accepted: 01/14/2013] [Indexed: 10/27/2022] Open
Abstract
Encapsulation of proteins in chaperonins is an important mechanism by which the cell prevents the accumulation of misfolded species in the cytosol. However, results from theory and simulation for repulsive cavities appear to be inconsistent with recent experimental results showing, if anything, a slowdown in folding rate for encapsulated Rhodanese. We study the folding of Rhodanese in GroEL, using coarse-grained molecular simulations of the complete system including chaperonin and substrate protein. We find that, by approximating the substrate:GroEL interactions as repulsive, we obtain a strong acceleration in rate of between one and two orders of magnitude; a similar result is obtained by representing the chaperonin as a simple spherical cavity. Remarkably, however, we find that using a carefully parameterized, sequence-based potential to capture specific residue-residue interactions between Rhodanese and the GroEL cavity walls induces a very strong reduction of the folding rates. The effect of the interactions is large enough to completely offset the effects of confinement, such that folding in some cases can be even slower than that of the unconfined protein. The origin of the slowdown appears to be stabilization--relative to repulsive confinement--of the unfolded state through binding to the cavity walls, rather than a reduction of the diffusion coefficient along the folding coordinate.
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Affiliation(s)
- Anshul Sirur
- University of Cambridge, Department of Chemistry, Cambridge, United Kingdom
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34
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Deighan M, Pfaendtner J. Exhaustively sampling peptide adsorption with metadynamics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:7999-8009. [PMID: 23706011 DOI: 10.1021/la4010664] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Simulating the adsorption of a peptide or protein and obtaining quantitative estimates of thermodynamic observables remains challenging for many reasons. One reason is the dearth of molecular scale experimental data available for validating such computational models. We also lack simulation methodologies that effectively address the dual challenges of simulating protein adsorption: overcoming strong surface binding and sampling conformational changes. Unbiased classical simulations do not address either of these challenges. Previous attempts that apply enhanced sampling generally focus on only one of the two issues, leaving the other to chance or brute force computing. To improve our ability to accurately resolve adsorbed protein orientation and conformational states, we have applied the Parallel Tempering Metadynamics in the Well-Tempered Ensemble (PTMetaD-WTE) method to several explicitly solvated protein/surface systems. We simulated the adsorption behavior of two peptides, LKα14 and LKβ15, onto two self-assembled monolayer (SAM) surfaces with carboxyl and methyl terminal functionalities. PTMetaD-WTE proved effective at achieving rapid convergence of the simulations, whose results elucidated different aspects of peptide adsorption including: binding free energies, side chain orientations, and preferred conformations. We investigated how specific molecular features of the surface/protein interface change the shape of the multidimensional peptide binding free energy landscape. Additionally, we compared our enhanced sampling technique with umbrella sampling and also evaluated three commonly used molecular dynamics force fields.
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Affiliation(s)
- Michael Deighan
- Department of Chemical Engineering, University of Washington, Seattle, Washington 98195, USA
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