1
|
Korshunova K, Kiuru J, Liekkinen J, Enkavi G, Vattulainen I, Bruininks BMH. Martini 3 OliGo̅mers: A Scalable Approach for Multimers and Fibrils in GROMACS. J Chem Theory Comput 2024; 20:7635-7645. [PMID: 39189419 PMCID: PMC11391574 DOI: 10.1021/acs.jctc.4c00677] [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: 08/28/2024]
Abstract
Martini 3 is a widely used coarse-grained simulation method for large-scale biomolecular simulations. It can be combined with a Go̅ model to realistically describe higher-order protein structures while allowing the folding and unfolding events. However, as of today, this method has largely been used only for individual monomers. In this article, we describe how the Go̅ model can be implemented within the framework of Martini 3 for a multimer system, taking into account both intramolecular and intermolecular interactions in an oligomeric protein system. We demonstrate the method by showing how it can be applied to both structural stability maintenance and assembly/disassembly of protein oligomers, using aquaporin tetramer, insulin dimer, and amyloid-β fibril as examples. We find that addition of intermolecular Go̅ potentials stabilizes the quaternary structure of proteins. The strength of the Go̅ potentials can be tuned so that the internal fluctuations of proteins match the behavior of atomistic simulation models, however, the results also show that the use of too strong intermolecular Go̅ potentials weakens the chemical specificity of oligomerization. The Martini-Go̅ model presented here enables the use of Go̅ potentials in oligomeric molecular systems in a computationally efficient and parallelizable manner, especially in the case of homopolymers, where the number of identical protein monomers is high. This paves the way for coarse-grained simulations of large protein complexes, such as viral protein capsids and prion fibrils, in complex biological environments.
Collapse
Affiliation(s)
- Ksenia Korshunova
- Department of Physics, University of Helsinki, FI-00014 Helsinki, Finland
| | - Julius Kiuru
- Department of Physics, University of Helsinki, FI-00014 Helsinki, Finland
| | - Juho Liekkinen
- Department of Physics, University of Helsinki, FI-00014 Helsinki, Finland
| | - Giray Enkavi
- Department of Physics, University of Helsinki, FI-00014 Helsinki, Finland
| | - Ilpo Vattulainen
- Department of Physics, University of Helsinki, FI-00014 Helsinki, Finland
| | - Bart M H Bruininks
- Department of Physics, University of Helsinki, FI-00014 Helsinki, Finland
| |
Collapse
|
2
|
Banerjee P, Monje-Galvan V, Voth GA. Cooperative Membrane Binding of HIV-1 Matrix Proteins. J Phys Chem B 2024; 128:2595-2606. [PMID: 38477117 PMCID: PMC10962350 DOI: 10.1021/acs.jpcb.3c06222] [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: 09/15/2023] [Revised: 02/24/2024] [Accepted: 02/27/2024] [Indexed: 03/14/2024]
Abstract
The HIV-1 assembly process begins with a newly synthesized Gag polyprotein being targeted to the inner leaflet of the plasma membrane of the infected cells to form immature viral particles. Gag-membrane interactions are mediated through the myristoylated (Myr) N-terminal matrix (MA) domain of Gag, which eventually multimerize on the membrane to form trimers and higher order oligomers. The study of the structure and dynamics of peripheral membrane proteins like MA has been challenging for both experimental and computational studies due to the complex transient dynamics of protein-membrane interactions. Although the roles of anionic phospholipids (PIP2, PS) and the Myr group in the membrane targeting and stable membrane binding of MA are now well-established, the cooperative interactions between the MA monomers and MA-membrane remain elusive in the context of viral assembly and release. Our present study focuses on the membrane binding dynamics of a higher order oligomeric structure of MA protein (a dimer of trimers), which has not been explored before. Employing time-lagged independent component analysis (tICA) to our microsecond-long trajectories, we investigate conformational changes of the matrix protein induced by membrane binding. Interestingly, the Myr switch of an MA monomer correlates with the conformational switch of adjacent monomers in the same trimer. Together, our findings suggest complex protein dynamics during the formation of the immature HIV-1 lattice; while MA trimerization facilitates Myr insertion, MA trimer-trimer interactions in the immature lattice can hinder the same.
Collapse
Affiliation(s)
- Puja Banerjee
- Department of Chemistry,
Chicago Center for Theoretical Chemistry, Institute for Biophysical
Dynamics, and James Franck Institute, The
University of Chicago, Chicago, Illinois 60637, United States
| | | | - Gregory A. Voth
- Department of Chemistry,
Chicago Center for Theoretical Chemistry, Institute for Biophysical
Dynamics, and James Franck Institute, The
University of Chicago, Chicago, Illinois 60637, United States
| |
Collapse
|
3
|
Banerjee P, Monje-Galvan V, Voth GA. Cooperative Membrane Binding of HIV-1 Matrix Proteins. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.22.559012. [PMID: 37790356 PMCID: PMC10542177 DOI: 10.1101/2023.09.22.559012] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
The HIV-1 assembly process begins with a newly synthesized Gag polyprotein being targeted to the inner leaflet of the plasma membrane of the infected cells to form immature viral particles. Gag-membrane interactions are mediated through the myristoylated(Myr) N-terminal matrix (MA) domain of Gag which eventually multimerize on the membrane to form trimers and higher-order oligomers. The study of the structure and dynamics of peripheral membrane proteins like MA has been challenging for both experimental and computational studies due to the complex dynamics of protein-membrane interactions. Although the roles of anionic phospholipids (PIP2, PS) and the Myr group in the membrane targeting and stable membrane binding of MA are now well-established, the cooperative interactions between MA monomers and MA-membrane still remain elusive. Our present study focuses on the membrane binding dynamics of a higher-order oligomeric structure of MA protein (a dimer of trimers), which has not been explored before. Employing time-lagged independent component analysis (tICA) to our microsecond-long trajectories, we investigate conformational changes of the matrix protein induced by membrane binding. Interestingly, the Myr switch of a MA monomer correlates with the conformational switch of adjacent monomers in the same trimer. Together, our findings suggest that MA trimerization facilitates Myr insertion, but MA trimer-trimer interactions in the lattice of immature HIV-1 particles can hinder the same. Additionally, local lipid density patterns of different lipid species provide a signature of the initial stage of lipid-domain formation upon membrane binding of the protein complex. TOC
Collapse
|
4
|
Abstract
A survey of protein databases indicates that the majority of enzymes exist in oligomeric forms, with about half of those found in the UniProt database being homodimeric. Understanding why many enzymes are in their dimeric form is imperative. Recent developments in experimental and computational techniques have allowed for a deeper comprehension of the cooperative interactions between the subunits of dimeric enzymes. This review aims to succinctly summarize these recent advancements by providing an overview of experimental and theoretical methods, as well as an understanding of cooperativity in substrate binding and the molecular mechanisms of cooperative catalysis within homodimeric enzymes. Focus is set upon the beneficial effects of dimerization and cooperative catalysis. These advancements not only provide essential case studies and theoretical support for comprehending dimeric enzyme catalysis but also serve as a foundation for designing highly efficient catalysts, such as dimeric organic catalysts. Moreover, these developments have significant implications for drug design, as exemplified by Paxlovid, which was designed for the homodimeric main protease of SARS-CoV-2.
Collapse
Affiliation(s)
- Ke-Wei Chen
- Lab of Computional Chemistry and Drug Design, State Key Laboratory of Chemical Oncogenomics, Peking University Shenzhen Graduate School, Shenzhen 518055, China
| | - Tian-Yu Sun
- Shenzhen Bay Laboratory, Shenzhen 518132, China
| | - Yun-Dong Wu
- Lab of Computional Chemistry and Drug Design, State Key Laboratory of Chemical Oncogenomics, Peking University Shenzhen Graduate School, Shenzhen 518055, China
- Shenzhen Bay Laboratory, Shenzhen 518132, China
| |
Collapse
|
5
|
Sedov I, Khaibrakhmanova D. Molecular Mechanisms of Inhibition of Protein Amyloid Fibril Formation: Evidence and Perspectives Based on Kinetic Models. Int J Mol Sci 2022; 23:13428. [PMID: 36362217 PMCID: PMC9657184 DOI: 10.3390/ijms232113428] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 10/29/2022] [Accepted: 10/31/2022] [Indexed: 11/06/2022] Open
Abstract
Inhibition of fibril formation is considered a possible treatment strategy for amyloid-related diseases. Understanding the molecular nature of inhibitor action is crucial for the design of drug candidates. In the present review, we describe the common kinetic models of fibril formation and classify known inhibitors by the mechanism of their interactions with the aggregating protein and its oligomers. This mechanism determines the step or steps of the aggregation process that become inhibited and the observed changes in kinetics and equilibrium of fibril formation. The results of numerous studies indicate that possible approaches to antiamyloid inhibitor discovery include the search for the strong binders of protein monomers, cappers blocking the ends of the growing fibril, or the species absorbing on the surface of oligomers preventing nucleation. Strongly binding inhibitors stabilizing the native state can be promising for the structured proteins while designing the drug candidates targeting disordered proteins is challenging.
Collapse
Affiliation(s)
- Igor Sedov
- Chemical Institute, Kazan Federal University, Kremlevskaya 18, 420008 Kazan, Russia
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 420111 Kazan, Russia
- Sirius University of Science and Technology, 1 Olympic Ave, 354340 Sochi, Russia
| | | |
Collapse
|
6
|
Maikawa CL, Nguyen LT, Mann JL, Appel EA. Formulation Excipients and Their Role in Insulin Stability and Association State in Formulation. Pharm Res 2022; 39:2721-2728. [PMID: 35978148 PMCID: PMC9633423 DOI: 10.1007/s11095-022-03367-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 08/10/2022] [Indexed: 10/15/2022]
Abstract
While excipients are often overlooked as the "inactive" ingredients in pharmaceutical formulations, they often play a critical role in protein stability and absorption kinetics. Recent work has identified an ultrafast absorbing insulin formulation that is the result of excipient modifications. Specifically, the insulin monomer can be isolated by replacing zinc and the phenolic preservative metacresol with phenoxyethanol as an antimicrobial agent and an amphiphilic acrylamide copolymer excipient for stability. A greater understanding is needed of the interplay between excipients, insulin association state, and stability in order to optimize this formulation. Here, we formulated insulin with different preservatives and stabilizing excipient concentrations using both insulin lispro and regular human insulin and assessed the insulin association states using analytical ultracentrifugation as well as formulation stability. We determined that phenoxyethanol is required to eliminate hexamers and promote a high monomer content even in a zinc-free lispro formulation. There is also a concentration dependent relationship between the concentration of polyacrylamide-based copolymer excipient and insulin stability, where a concentration greater than 0.1 g/mL copolymer is required for a mostly monomeric zinc-free lispro formulation to achieve stability exceeding that of Humalog in a stressed aging assay. Further, we determined that under the formulation conditions tested zinc-free regular human insulin remains primarily hexameric and is not at this time a promising candidate for rapid-acting formulations.
Collapse
Affiliation(s)
- Caitlin L Maikawa
- Department of Bioengineering, Stanford University, Stanford, 94305, USA
| | - Leslee T Nguyen
- Department of Biochemistry, Stanford University, Stanford, 94305, USA
| | - Joseph L Mann
- Department of Materials Science & Engineering, Stanford University, Stanford, 94305, USA
| | - Eric A Appel
- Department of Bioengineering, Stanford University, Stanford, 94305, USA. .,Department of Materials Science & Engineering, Stanford University, Stanford, 94305, USA. .,Department of Pediatrics (Endocrinology), Stanford University, Stanford, 94305, USA. .,ChEM-H Institute, Stanford University, Stanford, CA, 94305, USA. .,Woods Institute for the Environment, Stanford University, Stanford, CA, 94305, USA.
| |
Collapse
|
7
|
Counteractive Effects of Choline Geranate (CAGE) ILs and Ethanol on Insulin's Stability-A Leap Forward towards Oral Insulin Formulation. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27155031. [PMID: 35956982 PMCID: PMC9370287 DOI: 10.3390/molecules27155031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 07/29/2022] [Accepted: 08/05/2022] [Indexed: 12/02/2022]
Abstract
Choline geranate (CAGE) ionic liquids (ILs) stabilize insulin, thereby aiding its oral delivery, whereas ethanol (EtOH) affects its stability by disrupting the hydrophobic interactions. In this study, cognizance of the stabilization mechanism of insulin dimer in the presence of both CAGE ILs and EtOH mixtures is achieved through biased and unbiased molecular dynamics (MD) simulations. Here, two order parameters are employed to study the insulin dimer dissociation using well-tempered metadynamics (WT-MetaD). The stability of insulin is found to be strongly maintained until a 0.20 mole fraction of EtOH. Besides, higher concentrations of EtOH marginally affect the insulin stability. Moreover, geranate anions form a higher number of H-bonding interactions with water molecules, which aids insulin stabilization. Conversely, the addition of EtOH minimizes the water-mediated H-bonding interactions of geranate. Additionally, geranate traps the EtOH molecules, thereby preventing the interactions between insulin and EtOH. Furthermore, the free energy landscape (FEL) reveals the absence of dimer dissociation along with noticeable deviations in the distances R and the number of contacts Q. The dimerization free energy of insulin was calculated to be −16.1 kcal/mol at a 0.20 mole fraction of EtOH. Moreover, increments in mole fractions of EtOH effectuate a decrease in the insulin stability. Thus, the present study represents CAGE ILs as efficient insulin dimer stabilizes at low concentrations of EtOH.
Collapse
|
8
|
Mondal S, Cui Q. Coacervation of poly-electrolytes in the presence of lipid bilayers: mutual alteration of structure and morphology. Chem Sci 2022; 13:7933-7946. [PMID: 35865903 PMCID: PMC9258347 DOI: 10.1039/d2sc02013k] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 06/13/2022] [Indexed: 11/21/2022] Open
Abstract
Many intrinsically disordered peptides have been shown to undergo liquid-liquid phase separation and form complex coacervates, which play various regulatory roles in the cell. Recent experimental studies found that such phase separation processes may also occur at the lipid membrane surface and help organize biomolecules during signaling events; in some cases, phase separation of proteins at the membrane surface was also observed to lead to significant remodeling of the membrane morphology. The molecular mechanisms that govern the interactions between complex coacervates and lipid membranes and the impacts of such interactions on their structure and morphology, however, remain unclear. Here we study the coacervation of poly-glutamate (E30) and poly-lysine (K30) in the presence of lipid bilayers of different compositions. We carry out explicit-solvent coarse-grained molecular dynamics simulations by using the MARTINI (v3.0) force-field. We find that more than 20% anionic lipids are required for the coacervate to form stable contact with the bilayer. Upon wetting, the coacervate induces negative curvature to the bilayer and facilitates local lipid demixing, without any peptide insertion. The magnitude of negative curvature, extent of lipid demixing, and asphericity of the coacervate increase with the concentration of anionic lipids. Overall, we observe a decrease in the number of contacts among the polyelectrolytes as the droplet spreads over the bilayer. Therefore, unlike previous suggestions, interactions among polyelectrolytes do not constitute a driving force for the membrane bending upon wetting by the coacervate. Rather, analysis of interaction energy components suggests that bending of the membrane is favored by enhanced interactions between polyelectrolytes with lipids as well as with counterions. Kinetic studies reveal that, at the studied polyelectrolyte concentrations, the coacervate formation precedes bilayer wetting.
Collapse
Affiliation(s)
- Sayantan Mondal
- Department of Chemistry, Boston University 590 Commonwealth Avenue Boston MA 02215 USA (+1)-617-353-6189
| | - Qiang Cui
- Department of Chemistry, Boston University 590 Commonwealth Avenue Boston MA 02215 USA (+1)-617-353-6189
- Department of Physics, Boston University 590 Commonwealth Avenue Boston MA 02215 USA
- Department of Biomedical Engineering, Boston University 44 Cummington Mall Boston MA 02215 USA
| |
Collapse
|
9
|
Gorai B, Vashisth H. Progress in Simulation Studies of Insulin Structure and Function. Front Endocrinol (Lausanne) 2022; 13:908724. [PMID: 35795141 PMCID: PMC9252437 DOI: 10.3389/fendo.2022.908724] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 04/28/2022] [Indexed: 01/02/2023] Open
Abstract
Insulin is a peptide hormone known for chiefly regulating glucose level in blood among several other metabolic processes. Insulin remains the most effective drug for treating diabetes mellitus. Insulin is synthesized in the pancreatic β-cells where it exists in a compact hexameric architecture although its biologically active form is monomeric. Insulin exhibits a sequence of conformational variations during the transition from the hexamer state to its biologically-active monomer state. The structural transitions and the mechanism of action of insulin have been investigated using several experimental and computational methods. This review primarily highlights the contributions of molecular dynamics (MD) simulations in elucidating the atomic-level details of conformational dynamics in insulin, where the structure of the hormone has been probed as a monomer, dimer, and hexamer. The effect of solvent, pH, temperature, and pressure have been probed at the microscopic scale. Given the focus of this review on the structure of the hormone, simulation studies involving interactions between the hormone and its receptor are only briefly highlighted, and studies on other related peptides (e.g., insulin-like growth factors) are not discussed. However, the review highlights conformational dynamics underlying the activities of reported insulin analogs and mimetics. The future prospects for computational methods in developing promising synthetic insulin analogs are also briefly highlighted.
Collapse
Affiliation(s)
| | - Harish Vashisth
- Department of Chemical Engineering, University of New Hampshire, Durham, NH, United States
| |
Collapse
|
10
|
Töpfer K, Upadhyay M, Meuwly M. Quantitative molecular simulations. Phys Chem Chem Phys 2022; 24:12767-12786. [PMID: 35593769 PMCID: PMC9158373 DOI: 10.1039/d2cp01211a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Accepted: 04/30/2022] [Indexed: 11/21/2022]
Abstract
All-atom simulations can provide molecular-level insights into the dynamics of gas-phase, condensed-phase and surface processes. One important requirement is a sufficiently realistic and detailed description of the underlying intermolecular interactions. The present perspective provides an overview of the present status of quantitative atomistic simulations from colleagues' and our own efforts for gas- and solution-phase processes and for the dynamics on surfaces. Particular attention is paid to direct comparison with experiment. An outlook discusses present challenges and future extensions to bring such dynamics simulations even closer to reality.
Collapse
Affiliation(s)
- Kai Töpfer
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland.
| | - Meenu Upadhyay
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland.
| | - Markus Meuwly
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland.
| |
Collapse
|
11
|
Meuwly M. Atomistic Simulations for Reactions and Vibrational Spectroscopy in the Era of Machine Learning─ Quo Vadis?. J Phys Chem B 2022; 126:2155-2167. [PMID: 35286087 DOI: 10.1021/acs.jpcb.2c00212] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Atomistic simulations using accurate energy functions can provide molecular-level insight into functional motions of molecules in the gas and in the condensed phase. This Perspective delineates the present status of the field from the efforts of others and some of our own work and discusses open questions and future prospects. The combination of physics-based long-range representations using multipolar charge distributions and kernel representations for the bonded interactions is shown to provide realistic models for the exploration of the infrared spectroscopy of molecules in solution. For reactions, empirical models connecting dedicated energy functions for the reactant and product states allow statistically meaningful sampling of conformational space whereas machine-learned energy functions are superior in accuracy. The future combination of physics-based models with machine-learning techniques and integration into all-purpose molecular simulation software provides a unique opportunity to bring such dynamics simulations closer to reality.
Collapse
Affiliation(s)
- Markus Meuwly
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland
| |
Collapse
|
12
|
Chaudhary Y, Bhimalapuram P. Insulin aspart dimer dissociation in water. J Chem Phys 2022; 156:105106. [DOI: 10.1063/5.0078738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Yagya Chaudhary
- International Institute of Information Technology Hyderabad, India
| | - Prabhakar Bhimalapuram
- Center for Computational Natural Sciences and Bioinformatics, International Institute of Information Technology Hyderabad, India
| |
Collapse
|
13
|
Santra S, Jana M. Influence of Aqueous Arginine Solution on Regulating Conformational Stability and Hydration Properties of the Secondary Structural Segments of a Protein at Elevated Temperatures: A Molecular Dynamics Study. J Phys Chem B 2022; 126:1462-1476. [PMID: 35147426 DOI: 10.1021/acs.jpcb.1c09583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The effects of aqueous arginine solution on the conformational stability of the secondary structural segments of a globular protein, ubiquitin, and the structure and dynamics of the surrounding water and arginine were examined by performing atomistic molecular dynamics (MD) simulations. Attempts have been made to identify the osmolytic efficacy of arginine solution, and its influence in guiding the hydration properties of the protein at an elevated temperature of 450 K. The similar properties of the protein in pure water at elevated temperatures were computed and compared. Replica exchange MD simulation was performed to explore the arginine solution's sensitivity in stabilizing the protein conformations for a wide range of temperatures (300-450 K). It was observed that although all the helices and strands of the protein undergo unfolding at elevated temperature in pure water, they exhibited native-like conformational dynamics in the presence of arginine at both ambient and elevated temperatures. We find that the higher free energy barrier between the folded native and unfolded states of the protein primarily arises from the structural transformation of α-helix, relative to the strands. Our study revealed that the water structure around the secondary segments depends on the nature of amino acid compositions of the helices and strands. The reorientation of water dipoles around the helices and strands was found hindered due to the presence of arginine in the solution; such hindrance reduces the possibility of exchange of hydrogen bonds that formed between the secondary segments of protein and water (PW), and as a result, PW hydrogen bonds take longer time to relax than in pure water. On the other hand, the origin of slow relaxation of protein-arginine (PA) hydrogen bonds was identified to be due to the presence of different types of protein-bound arginine molecules, where arginine interacts with the secondary structural segments of the protein through multiple/bifurcated hydrogen bonds. These protein-bound arginine formed different kinds of bridged PA hydrogen bonds between amino acid residues of the same secondary segments or among multiple bonds and helped protein to conserve its native folded form firmly.
Collapse
Affiliation(s)
- Santanu Santra
- Molecular Simulation Laboratory, Department of Chemistry, National Institute of Technology, Rourkela 769008, India
| | - Madhurima Jana
- Molecular Simulation Laboratory, Department of Chemistry, National Institute of Technology, Rourkela 769008, India
| |
Collapse
|
14
|
Acharya S, Mondal S, Mukherjee S, Bagchi B. Rate of Insulin Dimer Dissociation: Interplay between Memory Effects and Higher Dimensionality. J Phys Chem B 2021; 125:9678-9691. [PMID: 34406771 DOI: 10.1021/acs.jpcb.1c03779] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We calculate the rate of dissociation of an insulin dimer into two monomers in water. The rate of this complex reaction is determined by multiple factors that are elucidated. By employing advanced sampling techniques, we first obtain the reaction free energy surface for the dimer dissociation as a function of two order parameters, namely, the distance between the center-of-mass of two monomers (R) and the number of cross-contacts (Q) among the backbone Cα atoms of two monomers. We then construct an orthogonal 2D reaction energy surface by introducing the reaction coordinate X to denote the minimum energy pathway and a conjugate coordinate Y that spans the orthogonal direction. The free energy landscape is rugged with multiple maxima and minima. We calculate the rate by employing not only the non-Markovian multidimensional rate theory but also several other theoretical approaches. The necessary reaction frequencies and the frictions are calculated from the time correlation function formalism. Our best estimate of the rate is 0.4 μs-1. Our study reveals interesting opposite influences of dimensionality and memory in determining the rate constant of the reaction. We gain interesting insights into the dimer dissociation process by looking directly at the trajectories obtained from molecular dynamics simulation.
Collapse
Affiliation(s)
- Subhajit Acharya
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, 560012 Karnataka, India
| | - Sayantan Mondal
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | - Saumyak Mukherjee
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, 560012 Karnataka, India
| | - Biman Bagchi
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, 560012 Karnataka, India
| |
Collapse
|
15
|
Mondal S, Mukherjee S, Acharya S, Bagchi B. Unfolding of Dynamical Events in the Early Stage of Insulin Dimer Dissociation. J Phys Chem B 2021; 125:7958-7966. [PMID: 34260242 DOI: 10.1021/acs.jpcb.1c03104] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The dissociation of an insulin dimer is an important biochemical event that could also serve as a prototype of dissociations in similar biomolecular assemblies. We use a recently developed multidimensional free energy landscape for insulin dimer dissociation to unearth the microscopic and mechanistic aspects of the initial stages of the process that could hold the key to understanding the stability and the rate. The following sequence of events occurs in the initial stages: (i) The backbone hydrogen bonds break partially at the antiparallel β-sheet junction, (ii) the two α-helices (chain B) move away from each other while several residues (chain A) move closer, and (iii) a flow of adjacent water molecules occurs into the junction region. Interestingly, the intermonomeric center-to-center distance does not increase, but the number of native contacts exhibits a sharp decrease. Subsequent steps involve further disengagement of hydrophobic groups. This process is slow because of an entropic bottleneck created by the existence of the large configuration space available in the native state (NS), which is inhabited by low-frequency conformational fluctuations. We carry out a density-of-states analyses in the dimer NS to unearth distinctive features not present in the monomers. These low-frequency modes are also responsible for a large entropic stabilization of the NS. Hydrophobic disengagement in the early stage leads to the formation of a twisted intermediate state which itself is a metastable minimum (IS-1). The subsequent progress leads to another dimeric complex (IS-2), which is on the dissociative pathway and characterized by a further decrease in the native contacts. The dissociation process provides insights into the workings of a biomolecular assembly.
Collapse
Affiliation(s)
- Sayantan Mondal
- Solid State and Structural Chemistry Unit, Indian Institute of Science, C. V. Raman Road, Bengaluru, Karnataka 560 012, India
| | - Saumyak Mukherjee
- Solid State and Structural Chemistry Unit, Indian Institute of Science, C. V. Raman Road, Bengaluru, Karnataka 560 012, India
| | - Subhajit Acharya
- Solid State and Structural Chemistry Unit, Indian Institute of Science, C. V. Raman Road, Bengaluru, Karnataka 560 012, India
| | - Biman Bagchi
- Solid State and Structural Chemistry Unit, Indian Institute of Science, C. V. Raman Road, Bengaluru, Karnataka 560 012, India
| |
Collapse
|
16
|
Kalayan J, Curtis RA, Warwicker J, Henchman RH. Thermodynamic Origin of Differential Excipient-Lysozyme Interactions. Front Mol Biosci 2021; 8:689400. [PMID: 34179093 PMCID: PMC8226134 DOI: 10.3389/fmolb.2021.689400] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 05/25/2021] [Indexed: 01/15/2023] Open
Abstract
Understanding the intricate interplay of interactions between proteins, excipients, ions and water is important to achieve the effective purification and stable formulation of protein therapeutics. The free energy of lysozyme interacting with two kinds of polyanionic excipients, citrate and tripolyphosphate, together with sodium chloride and TRIS-buffer, are analysed in multiple-walker metadynamics simulations to understand why tripolyphosphate causes lysozyme to precipitate but citrate does not. The resulting multiscale decomposition of energy and entropy components for water, sodium chloride, excipients and lysozyme reveals that lysozyme is more stabilised by the interaction of tripolyphosphate with basic residues. This is accompanied by more sodium ions being released into solution from tripolyphosphate than for citrate, whilst the latter instead has more water molecules released into solution. Even though lysozyme aggregation is not directly probed in this study, these different mechanisms are suspected to drive the cross-linking between lysozyme molecules with vacant basic residues, ultimately leading to precipitation.
Collapse
Affiliation(s)
- Jas Kalayan
- Manchester Institute of Biotechnology, The University of Manchester, Manchester, United Kingdom.,Department of Chemistry, The University of Manchester, Manchester, United Kingdom
| | - Robin A Curtis
- Manchester Institute of Biotechnology, The University of Manchester, Manchester, United Kingdom.,Departments of Chemical Engineering and Analytical Science, The University of Manchester, Manchester, United Kingdom
| | - Jim Warwicker
- Manchester Institute of Biotechnology, The University of Manchester, Manchester, United Kingdom.,Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
| | - Richard H Henchman
- Manchester Institute of Biotechnology, The University of Manchester, Manchester, United Kingdom.,Department of Chemistry, The University of Manchester, Manchester, United Kingdom.,Faculty of Medicine and Health, Sydney Medical School, The University of Sydney, Sydney, NSW, Australia
| |
Collapse
|
17
|
Hsu DJ, Leshchev D, Kosheleva I, Kohlstedt KL, Chen LX. Unfolding bovine α-lactalbumin with T-jump: Characterizing disordered intermediates via time-resolved x-ray solution scattering and molecular dynamics simulations. J Chem Phys 2021; 154:105101. [PMID: 33722011 PMCID: PMC7943248 DOI: 10.1063/5.0039194] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 02/04/2021] [Indexed: 02/07/2023] Open
Abstract
The protein folding process often proceeds through partially folded transient states. Therefore, a structural understanding of these disordered states is crucial for developing mechanistic models of the folding process. Characterization of unfolded states remains challenging due to their disordered nature, and incorporating multiple methods is necessary. Combining the time-resolved x-ray solution scattering (TRXSS) signal with molecular dynamics (MD), we are able to characterize transient partially folded states of bovine α-lactalbumin, a model system widely used for investigation of molten globule states, during its unfolding triggered by a temperature jump. We track the unfolding process between 20 µs and 70 ms and demonstrate that it passes through three distinct kinetic states. The scattering signals associated with these transient species are then analyzed with TRXSS constrained MD simulations to produce protein structures that are compatible with the input signals. Without utilizing any experimentally extracted kinetic information, the constrained MD simulation successfully drove the protein to an intermediate molten globule state; signals for two later disordered states are refined to terminal unfolded states. From our examination of the structural characteristics of these disordered states, we discuss the implications disordered states have on the folding process, especially on the folding pathway. Finally, we discuss the potential applications and limitations of this method.
Collapse
Affiliation(s)
- Darren J. Hsu
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
| | - Denis Leshchev
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
| | - Irina Kosheleva
- Center for Advanced Radiation Sources, The University of Chicago, Chicago, Illinois 60637, USA
| | - Kevin L. Kohlstedt
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
| | - Lin X. Chen
- Authors to whom correspondence should be addressed: and
| |
Collapse
|
18
|
Antoszewski A, Feng CJ, Vani BP, Thiede EH, Hong L, Weare J, Tokmakoff A, Dinner AR. Insulin Dissociates by Diverse Mechanisms of Coupled Unfolding and Unbinding. J Phys Chem B 2020; 124:5571-5587. [PMID: 32515958 PMCID: PMC7774804 DOI: 10.1021/acs.jpcb.0c03521] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The protein hormone insulin exists in various oligomeric forms, and a key step in binding its cellular receptor is dissociation of the dimer. This dissociation process and its corresponding association process have come to serve as paradigms of coupled (un)folding and (un)binding more generally. Despite its fundamental and practical importance, the mechanism of insulin dimer dissociation remains poorly understood. Here, we use molecular dynamics simulations, leveraging recent developments in umbrella sampling, to characterize the energetic and structural features of dissociation in unprecedented detail. We find that the dissociation is inherently multipathway with limiting behaviors corresponding to conformational selection and induced fit, the two prototypical mechanisms of coupled folding and binding. Along one limiting path, the dissociation leads to detachment of the C-terminal segment of the insulin B chain from the protein core, a feature believed to be essential for receptor binding. We simulate IR spectroscopy experiments to aid in interpreting current experiments and identify sites where isotopic labeling can be most effective for distinguishing the contributions of the limiting mechanisms.
Collapse
Affiliation(s)
- Adam Antoszewski
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - Chi-Jui Feng
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - Bodhi P Vani
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - Erik H Thiede
- Department of Computer Science, The University of Chicago, Chicago, Illinois 60637, United States
- Department of Statistics, The University of Chicago, Chicago, Illinois 60637, United States
| | - Lu Hong
- Graduate Program in Biophysical Sciences, The University of Chicago, Chicago, Illinois 60637, United States
| | - Jonathan Weare
- Courant Institute of Mathematical Sciences, New York University, New York, New York 10012, United States
| | - Andrei Tokmakoff
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
- James Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States
| | - Aaron R Dinner
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
- James Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States
| |
Collapse
|
19
|
Zhang XX, Tokmakoff A. Revealing the Dynamical Role of Co-solvents in the Coupled Folding and Dimerization of Insulin. J Phys Chem Lett 2020; 11:4353-4358. [PMID: 32401513 PMCID: PMC7850624 DOI: 10.1021/acs.jpclett.0c00982] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Solvent-protein interactions are important for protein biological functions, especially for a coupled folding and binding system such as insulin. By monitoring the change in the conformation of insulin dimers during dissociation with temperature-jump infrared spectroscopy, we show that co-solvents can significantly destabilize the dimers by perturbing their hydrophobic center. The transition from the native to intermediate dimer state is observed as the buried residues are exposed to solvents in the presence of 10% dimethyl sulfoxide and with α-helices unfolding when ethanol is present, which reduces the dissociation time dramatically to 50% and 20% of the value in a D2O solution, respectively. We propose a self-consistent analysis using complementary methods to resolve this coupled folding and binding process and obtain a much higher rate of monomer association than of intermediate folding. Our results demonstrate that the conformational changes are critical in dimer formation and strongly affected by co-solvents.
Collapse
Affiliation(s)
- Xin-Xing Zhang
- Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, The University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United States
| | - Andrei Tokmakoff
- Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, The University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United States
| |
Collapse
|
20
|
Dynamical control by water at a molecular level in protein dimer association and dissociation. Proc Natl Acad Sci U S A 2020; 117:2302-2308. [PMID: 31969453 DOI: 10.1073/pnas.1908379117] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Water, often termed as the "lubricant of life," is expected to play an active role in navigating protein dissociation-association reactions. In order to unearth the molecular details, we first compute the free-energy surface (FES) of insulin dimer dissociation employing metadynamics simulation, and then carry out analyses of insulin dimerization and dissociation using atomistic molecular-dynamics simulation in explicit water. We select two sets of initial configurations from 1) the dissociated state and 2) the transition state, and follow time evolution using several long trajectories (∼1-2 μs). During the process we not only monitor configuration of protein monomers, but also the properties of water. Although the equilibrium structural properties of water between the two monomers approach bulklike characteristics at a separation distance of ∼5 nm, the dynamics differ considerably. The complex association process is observed to be accompanied by several structural and dynamical changes of the system, such as large-scale correlated water density fluctuations, coupled conformational fluctuation of protein monomers, a dewettinglike transition with the change of intermonomeric distance RMM from ∼4 to ∼2 nm, orientation of monomers and hydrophobic hydration in the monomers. A quasistable, solvent-shared, protein monomer pair (SSPMP) forms at around 2 nm during association process which is a local free-energy minimum having ∼50-60% of native contacts. Simulations starting with arrangements sampled from the transition state (TS) of the dimer dissociation reveal that the final outcome depends on relative orientation of the backbone in the "hotspot" region.
Collapse
|
21
|
Maikawa CL, Smith AAA, Zou L, Meis CM, Mann JL, Webber MJ, Appel EA. Stable Monomeric Insulin Formulations Enabled by Supramolecular PEGylation of Insulin Analogues. ADVANCED THERAPEUTICS 2020; 3:1900094. [PMID: 32190729 PMCID: PMC7079736 DOI: 10.1002/adtp.201900094] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Indexed: 12/17/2022]
Abstract
Current "fast-acting" insulin analogues contain amino acid modifications meant to inhibit dimer formation and shift the equilibrium of association states toward the monomeric state. However, the insulin monomer is highly unstable and current formulation techniques require insulin to primarily exist as hexamers to prevent aggregation into inactive and immunogenic amyloids. Insulin formulation excipients have thus been traditionally selected to promote insulin association into the hexameric form to enhance formulation stability. This study exploits a novel excipient for the supramolecular PEGylation of insulin analogues, including aspart and lispro, to enhance the stability and maximize the prevalence of insulin monomers in formulation. Using multiple techniques, it is demonstrated that judicious choice of formulation excipients (tonicity agents and parenteral preservatives) enables insulin analogue formulations with 70-80% monomer and supramolecular PEGylation imbued stability under stressed aging for over 100 h without altering the insulin association state. Comparatively, commercial "fast-acting" formulations contain less than 1% monomer and remain stable for only 10 h under the same stressed aging conditions. This simple and effective formulation approach shows promise for next-generation ultrafast insulin formulations with a short duration of action that can reduce the risk of post-prandial hypoglycemia in the treatment of diabetes.
Collapse
Affiliation(s)
- Caitlin L Maikawa
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Anton A A Smith
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Lei Zou
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Catherine M Meis
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Joseph L Mann
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Matthew J Webber
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Eric A Appel
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| |
Collapse
|
22
|
Mukherjee S, Deshmukh AA, Mondal S, Gopal B, Bagchi B. Destabilization of Insulin Hexamer in Water–Ethanol Binary Mixture. J Phys Chem B 2019; 123:10365-10375. [DOI: 10.1021/acs.jpcb.9b07689] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Saumyak Mukherjee
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru 560012, India
| | - Ashish A. Deshmukh
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru 560012, India
| | - Sayantan Mondal
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru 560012, India
| | | | - Biman Bagchi
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru 560012, India
| |
Collapse
|