1
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Jin J, Reichman DR. Hierarchical Framework for Predicting Entropies in Bottom-Up Coarse-Grained Models. J Phys Chem B 2024; 128:3182-3199. [PMID: 38507575 DOI: 10.1021/acs.jpcb.3c07624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/22/2024]
Abstract
The thermodynamic entropy of coarse-grained (CG) models stands as one of the most important properties for quantifying the missing information during the CG process and for establishing transferable (or extendible) CG interactions. However, performing additional CG simulations on top of model construction often leads to significant additional computational overhead. In this work, we propose a simple hierarchical framework for predicting the thermodynamic entropies of various molecular CG systems. Our approach employs a decomposition of the CG interactions, enabling the estimation of the CG partition function and thermodynamic properties a priori. Starting from the ideal gas description, we leverage classical perturbation theory to systematically incorporate simple yet essential interactions, ranging from the hard sphere model to the generalized van der Waals model. Additionally, we propose an alternative approach based on multiparticle correlation functions, allowing for systematic improvements through higher-order correlations. Numerical applications to molecular liquids validate the high fidelity of our approach, and our computational protocols demonstrate that a reduced model with simple energetics can reasonably estimate the thermodynamic entropy of CG models without performing any CG simulations. Overall, our findings present a systematic framework for estimating not only the entropy but also other thermodynamic properties of CG models, relying solely on information from the reference system.
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Affiliation(s)
- Jaehyeok Jin
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, United States
| | - David R Reichman
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, United States
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2
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Jin J, Hwang J, Voth GA. Gaussian representation of coarse-grained interactions of liquids: Theory, parametrization, and transferability. J Chem Phys 2023; 159:184105. [PMID: 37942867 DOI: 10.1063/5.0160567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 10/06/2023] [Indexed: 11/10/2023] Open
Abstract
Coarse-grained (CG) interactions determined via bottom-up methodologies can faithfully reproduce the structural correlations observed in fine-grained (atomistic resolution) systems, yet they can suffer from limited extensibility due to complex many-body correlations. As part of an ongoing effort to understand and improve the applicability of bottom-up CG models, we propose an alternative approach to address both accuracy and transferability. Our main idea draws from classical perturbation theory to partition the hard sphere repulsive term from effective CG interactions. We then introduce Gaussian basis functions corresponding to the system's characteristic length by linking these Gaussian sub-interactions to the local particle densities at each coordination shell. The remaining perturbative long-range interaction can be treated as a collective solvation interaction, which we show exhibits a Gaussian form derived from integral equation theories. By applying this numerical parametrization protocol to CG liquid systems, our microscopic theory elucidates the emergence of Gaussian interactions in common phenomenological CG models. To facilitate transferability for these reduced descriptions, we further infer equations of state to determine the sub-interaction parameter as a function of the system variables. The reduced models exhibit excellent transferability across the thermodynamic state points. Furthermore, we propose a new strategy to design the cross-interactions between distinct CG sites in liquid mixtures. This involves combining each Gaussian in the proper radial domain, yielding accurate CG potentials of mean force and structural correlations for multi-component systems. Overall, our findings establish a solid foundation for constructing transferable bottom-up CG models of liquids with enhanced extensibility.
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Affiliation(s)
- Jaehyeok Jin
- Department of Chemistry, Chicago Center for Theoretical Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, The University of Chicago, 5735 S. Ellis Ave., Chicago, Illinois 60637, USA
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, USA
| | - Jisung Hwang
- Department of Statistics, The University of Chicago, 5747 S. Ellis Ave., Chicago, Illinois 60637, USA
| | - Gregory A Voth
- Department of Chemistry, Chicago Center for Theoretical Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, The University of Chicago, 5735 S. Ellis Ave., Chicago, Illinois 60637, USA
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3
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Qian Y, Evans D, Mishra B, Fu Y, Liu ZH, Guo S, Johnson ME. Temporal control by cofactors prevents kinetic trapping in retroviral Gag lattice assembly. Biophys J 2023; 122:3173-3190. [PMID: 37393432 PMCID: PMC10432227 DOI: 10.1016/j.bpj.2023.06.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Revised: 06/21/2023] [Accepted: 06/27/2023] [Indexed: 07/03/2023] Open
Abstract
For retroviruses like HIV to proliferate, they must form virions shaped by the self-assembly of Gag polyproteins into a rigid lattice. This immature Gag lattice has been structurally characterized and reconstituted in vitro, revealing the sensitivity of lattice assembly to multiple cofactors. Due to this sensitivity, the energetic criterion for forming stable lattices is unknown, as are their corresponding rates. Here, we use a reaction-diffusion model designed from the cryo-ET structure of the immature Gag lattice to map a phase diagram of assembly outcomes controlled by experimentally constrained rates and free energies, over experimentally relevant timescales. We find that productive assembly of complete lattices in bulk solution is extraordinarily difficult due to the large size of this ∼3700 monomer complex. Multiple Gag lattices nucleate before growth can complete, resulting in loss of free monomers and frequent kinetic trapping. We therefore derive a time-dependent protocol to titrate or "activate" the Gag monomers slowly within the solution volume, mimicking the biological roles of cofactors. This general strategy works remarkably well, yielding productive growth of self-assembled lattices for multiple interaction strengths and binding rates. By comparing to the in vitro assembly kinetics, we can estimate bounds on rates of Gag binding to Gag and the cellular cofactor IP6. Our results show that Gag binding to IP6 can provide the additional time delay necessary to support smooth growth of the immature lattice with relatively fast assembly kinetics, mostly avoiding kinetic traps. Our work provides a foundation for predicting and disrupting formation of the immature Gag lattice via targeting specific protein-protein binding interactions.
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Affiliation(s)
- Yian Qian
- TC Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland
| | - Daniel Evans
- TC Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland
| | - Bhavya Mishra
- Department of Physics, and Center for Cellular and Biomolecular Machines, University of California, Merced, California
| | - Yiben Fu
- TC Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland
| | - Zixiu Hugh Liu
- TC Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland
| | - Sikao Guo
- TC Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland
| | - Margaret E Johnson
- TC Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland.
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4
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Lynch DL, Pavlova A, Fan Z, Gumbart JC. Understanding Virus Structure and Dynamics through Molecular Simulations. J Chem Theory Comput 2023. [PMID: 37192279 DOI: 10.1021/acs.jctc.3c00116] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Viral outbreaks remain a serious threat to human and animal populations and motivate the continued development of antiviral drugs and vaccines, which in turn benefits from a detailed understanding of both viral structure and dynamics. While great strides have been made in characterizing these systems experimentally, molecular simulations have proven to be an essential, complementary approach. In this work, we review the contributions of molecular simulations to the understanding of viral structure, functional dynamics, and processes related to the viral life cycle. Approaches ranging from coarse-grained to all-atom representations are discussed, including current efforts at modeling complete viral systems. Overall, this review demonstrates that computational virology plays an essential role in understanding these systems.
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Affiliation(s)
- Diane L Lynch
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Anna Pavlova
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Zixing Fan
- Interdisciplinary Bioengineering Graduate Program, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - James C Gumbart
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
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5
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Lei X, Gonçalves-Carneiro D, Zang TM, Bieniasz PD. Initiation of HIV-1 Gag lattice assembly is required for recognition of the viral genome packaging signal. eLife 2023; 12:e83548. [PMID: 36688533 PMCID: PMC9908077 DOI: 10.7554/elife.83548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Accepted: 01/20/2023] [Indexed: 01/24/2023] Open
Abstract
The encapsidation of HIV-1 gRNA into virions is enabled by the binding of the nucleocapsid (NC) domain of the HIV-1 Gag polyprotein to the structured viral RNA packaging signal (Ψ) at the 5' end of the viral genome. However, the subcellular location and oligomeric status of Gag during the initial Gag-Ψ encounter remain uncertain. Domains other than NC, such as capsid (CA), may therefore indirectly affect RNA recognition. To investigate the contribution of Gag domains to Ψ recognition in a cellular environment, we performed protein-protein crosslinking and protein-RNA crosslinking immunoprecipitation coupled with sequencing (CLIP-seq) experiments. We demonstrate that NC alone does not bind specifically to Ψ in living cells, whereas full-length Gag and a CANC subdomain bind to Ψ with high specificity. Perturbation of the Ψ RNA structure or NC zinc fingers affected CANC:Ψ binding specificity. Notably, CANC variants with substitutions that disrupt CA:CA dimer, trimer, or hexamer interfaces in the immature Gag lattice also affected RNA binding, and mutants that were unable to assemble a nascent Gag lattice were unable to specifically bind to Ψ. Artificially multimerized NC domains did not specifically bind Ψ. CA variants with substitutions in inositol phosphate coordinating residues that prevent CA hexamerization were also deficient in Ψ binding and second-site revertant mutants that restored CA assembly also restored specific binding to Ψ. Overall, these data indicate that the correct assembly of a nascent immature CA lattice is required for the specific interaction between Gag and Ψ in cells.
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Affiliation(s)
- Xiao Lei
- Laboratory of Retrovirology, Rockefeller UniversityNew YorkUnited States
| | | | - Trinity M Zang
- Laboratory of Retrovirology, Rockefeller UniversityNew YorkUnited States
- Howard Hughes Medical Institute, The Rockefeller UniversityNew York, New YorkUnited States
| | - Paul D Bieniasz
- Laboratory of Retrovirology, Rockefeller UniversityNew YorkUnited States
- Howard Hughes Medical Institute, The Rockefeller UniversityNew York, New YorkUnited States
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6
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Jin J, Schweizer KS, Voth GA. Understanding dynamics in coarse-grained models. I. Universal excess entropy scaling relationship. J Chem Phys 2023; 158:034103. [PMID: 36681649 DOI: 10.1063/5.0116299] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Coarse-grained (CG) models facilitate an efficient exploration of complex systems by reducing the unnecessary degrees of freedom of the fine-grained (FG) system while recapitulating major structural correlations. Unlike structural properties, assessing dynamic properties in CG modeling is often unfeasible due to the accelerated dynamics of the CG models, which allows for more efficient structural sampling. Therefore, the ultimate goal of the present series of articles is to establish a better correspondence between the FG and CG dynamics. To assess and compare dynamical properties in the FG and the corresponding CG models, we utilize the excess entropy scaling relationship. For Paper I of this series, we provide evidence that the FG and the corresponding CG counterpart follow the same universal scaling relationship. By carefully reviewing and examining the literature, we develop a new theory to calculate excess entropies for the FG and CG systems while accounting for entropy representability. We demonstrate that the excess entropy scaling idea can be readily applied to liquid water and methanol systems at both the FG and CG resolutions. For both liquids, we reveal that the scaling exponents remain unchanged from the coarse-graining process, indicating that the scaling behavior is universal for the same underlying molecular systems. Combining this finding with the concept of mapping entropy in CG models, we show that the missing entropy plays an important role in accelerating the CG dynamics.
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Affiliation(s)
- Jaehyeok Jin
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA
| | - Kenneth S Schweizer
- Department of Material Science, Department of Chemistry, Department of Chemical and Biomolecular Engineering, and Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801, USA
| | - 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, USA
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7
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Gupta M, Pak AJ, Voth GA. Critical mechanistic features of HIV-1 viral capsid assembly. SCIENCE ADVANCES 2023; 9:eadd7434. [PMID: 36608139 PMCID: PMC9821859 DOI: 10.1126/sciadv.add7434 10.1126/sciadv.add7434] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 12/08/2022] [Indexed: 11/04/2023]
Abstract
The maturation of HIV-1 capsid protein (CA) into a cone-shaped lattice capsid is critical for viral infectivity. CA can self-assemble into a range of capsid morphologies made of ~175 to 250 hexamers and 12 pentamers. The cellular polyanion inositol hexakisphosphate (IP6) has recently been demonstrated to facilitate conical capsid formation by coordinating a ring of arginine residues within the central cavity of capsid hexamers and pentamers. However, the kinetic interplay of events during IP6 and CA coassembly is unclear. In this work, we use coarse-grained molecular dynamics simulations to elucidate the molecular mechanism of capsid formation, including the role played by IP6. We show that IP6, in small quantities at first, promotes curvature generation by trapping pentameric defects in the growing lattice and shifts assembly behavior toward kinetically favored outcomes. Our analysis also suggests that IP6 can stabilize metastable capsid intermediates and can induce structural pleomorphism in mature capsids.
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Affiliation(s)
- Manish Gupta
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, IL 60637, USA
| | | | - Gregory A. Voth
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, IL 60637, USA
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8
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Gupta M, Pak AJ, Voth GA. Critical mechanistic features of HIV-1 viral capsid assembly. SCIENCE ADVANCES 2023; 9:eadd7434. [PMID: 36608139 PMCID: PMC9821859 DOI: 10.1126/sciadv.add7434+10.1126/sciadv.add7434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 12/08/2022] [Indexed: 01/21/2024]
Abstract
The maturation of HIV-1 capsid protein (CA) into a cone-shaped lattice capsid is critical for viral infectivity. CA can self-assemble into a range of capsid morphologies made of ~175 to 250 hexamers and 12 pentamers. The cellular polyanion inositol hexakisphosphate (IP6) has recently been demonstrated to facilitate conical capsid formation by coordinating a ring of arginine residues within the central cavity of capsid hexamers and pentamers. However, the kinetic interplay of events during IP6 and CA coassembly is unclear. In this work, we use coarse-grained molecular dynamics simulations to elucidate the molecular mechanism of capsid formation, including the role played by IP6. We show that IP6, in small quantities at first, promotes curvature generation by trapping pentameric defects in the growing lattice and shifts assembly behavior toward kinetically favored outcomes. Our analysis also suggests that IP6 can stabilize metastable capsid intermediates and can induce structural pleomorphism in mature capsids.
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Affiliation(s)
- Manish Gupta
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, IL 60637, USA
| | | | - Gregory A. Voth
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, IL 60637, USA
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9
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Gupta M, Pak AJ, Voth GA. Critical mechanistic features of HIV-1 viral capsid assembly. SCIENCE ADVANCES 2023; 9:eadd7434. [PMID: 36608139 PMCID: PMC9821859 DOI: 10.1126/sciadv.add7434] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 12/08/2022] [Indexed: 05/29/2023]
Abstract
The maturation of HIV-1 capsid protein (CA) into a cone-shaped lattice capsid is critical for viral infectivity. CA can self-assemble into a range of capsid morphologies made of ~175 to 250 hexamers and 12 pentamers. The cellular polyanion inositol hexakisphosphate (IP6) has recently been demonstrated to facilitate conical capsid formation by coordinating a ring of arginine residues within the central cavity of capsid hexamers and pentamers. However, the kinetic interplay of events during IP6 and CA coassembly is unclear. In this work, we use coarse-grained molecular dynamics simulations to elucidate the molecular mechanism of capsid formation, including the role played by IP6. We show that IP6, in small quantities at first, promotes curvature generation by trapping pentameric defects in the growing lattice and shifts assembly behavior toward kinetically favored outcomes. Our analysis also suggests that IP6 can stabilize metastable capsid intermediates and can induce structural pleomorphism in mature capsids.
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10
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Jana AK, May ER. Atomistic dynamics of a viral infection process: Release of membrane lytic peptides from a non-enveloped virus. SCIENCE ADVANCES 2021; 7:7/16/eabe1761. [PMID: 33853772 PMCID: PMC8046363 DOI: 10.1126/sciadv.abe1761] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 02/23/2021] [Indexed: 05/13/2023]
Abstract
Molecular simulations have played an instrumental role in uncovering the structural dynamics and physical properties of virus capsids. In this work, we move beyond equilibrium physicochemical characterization of a virus system to study a stage of the infection process that is required for viral proliferation. Despite many biochemical and functional studies, the molecular mechanism of host cell entry by non-enveloped viruses remains largely unresolved. Flock House virus (FHV) is a model system for non-enveloped viruses and is the subject of the current study. FHV infects through the acid-dependent endocytic pathway, where low pH triggers externalization of membrane-disrupting (γ) peptides from the capsid interior. Using all-atom equilibrium and enhanced sampling simulations, the mechanism and energetics of γ peptide liberation and the effect of pH on this process are investigated. Our computations agree with experimental findings and reveal nanoscopic details regarding the pH control mechanism, which are not readily accessible in experiments.
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Affiliation(s)
- Asis K Jana
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA
| | - Eric R May
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA.
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11
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Jin J, Pak AJ, Han Y, Voth GA. A new one-site coarse-grained model for water: Bottom-up many-body projected water (BUMPer). II. Temperature transferability and structural properties at low temperature. J Chem Phys 2021; 154:044105. [PMID: 33514078 PMCID: PMC7826166 DOI: 10.1063/5.0026652] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 12/14/2020] [Indexed: 11/14/2022] Open
Abstract
A number of studies have constructed coarse-grained (CG) models of water to understand its anomalous properties. Most of these properties emerge at low temperatures, and an accurate CG model needs to be applicable to these low-temperature ranges. However, direct use of CG models parameterized from other temperatures, e.g., room temperature, encounters a problem known as transferability, as the CG potential essentially follows the form of the many-body CG free energy function. Therefore, temperature-dependent changes to CG interactions must be accounted for. The collective behavior of water at low temperature is generally a many-body process, which often motivates the use of expensive many-body terms in the CG interactions. To surmount the aforementioned problems, we apply the Bottom-Up Many-Body Projected Water (BUMPer) CG model constructed from Paper I to study the low-temperature behavior of water. We report for the first time that the embedded three-body interaction enables BUMPer, despite its pairwise form, to capture the growth of ice at the ice/water interface with corroborating many-body correlations during the crystal growth. Furthermore, we propose temperature transferable BUMPer models that are indirectly constructed from the free energy decomposition scheme. Changes in CG interactions and corresponding structures are faithfully recapitulated by this framework. We further extend BUMPer to examine its ability to predict the structure, density, and diffusion anomalies by employing an alternative analysis based on structural correlations and pairwise potential forms to predict such anomalies. The presented analysis highlights the existence of these anomalies in the low-temperature regime and overcomes potential transferability problems.
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Affiliation(s)
- Jaehyeok Jin
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA
| | - Alexander J. Pak
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA
| | - Yining Han
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA
| | - 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, USA
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12
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Samsudin F, Gan SKE, Bond PJ. The impact of Gag non-cleavage site mutations on HIV-1 viral fitness from integrative modelling and simulations. Comput Struct Biotechnol J 2020; 19:330-342. [PMID: 33425260 PMCID: PMC7779841 DOI: 10.1016/j.csbj.2020.12.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 12/15/2020] [Accepted: 12/16/2020] [Indexed: 01/19/2023] Open
Abstract
The high mutation rate in retroviruses is one of the leading causes of drug resistance. In human immunodeficiency virus type-1 (HIV-1), synergistic mutations in its protease and the protease substrate - the Group-specific antigen (Gag) polyprotein - work together to confer drug resistance against protease inhibitors and compensate the mutations affecting viral fitness. Some Gag mutations can restore Gag-protease binding, yet most Gag-protease correlated mutations occur outside of the Gag cleavage site. To investigate the molecular basis for this, we now report multiscale modelling approaches to investigate various sequentially cleaved Gag products in the context of clinically relevant mutations that occur outside of the cleavage sites, including simulations of the largest Gag proteolytic product in its viral membrane-bound state. We found that some mutations, such as G123E and H219Q, involve direct interaction with cleavage site residues to influence their local environment, while certain mutations in the matrix domain lead to the enrichment of lipids important for Gag targeting and assembly. Collectively, our results reveal why non-cleavage site mutations have far-reaching implications outside of Gag proteolysis, with important consequences for drugging Gag maturation intermediates and tackling protease inhibitor resistance.
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Affiliation(s)
- Firdaus Samsudin
- Bioinformatics Institute (A*STAR), 30 Biopolis Street, #07-01 Matrix, Singapore 138671, Singapore
| | - Samuel Ken-En Gan
- Bioinformatics Institute (A*STAR), 30 Biopolis Street, #07-01 Matrix, Singapore 138671, Singapore
- Antibody & Product Development Lab – Large Molecule Innovation, Experimental Drug Development Centre (A*STAR), 138670 Singapore, Singapore
- p53 Laboratory (A*STAR), 138648 Singapore, Singapore
| | - Peter J. Bond
- Bioinformatics Institute (A*STAR), 30 Biopolis Street, #07-01 Matrix, Singapore 138671, Singapore
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
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13
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Valbuena A, Maity S, Mateu MG, Roos WH. Visualization of Single Molecules Building a Viral Capsid Protein Lattice through Stochastic Pathways. ACS NANO 2020; 14:8724-8734. [PMID: 32633498 PMCID: PMC7392527 DOI: 10.1021/acsnano.0c03207] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 06/26/2020] [Indexed: 05/20/2023]
Abstract
Direct visualization of pathways followed by single molecules while they spontaneously self-assemble into supramolecular biological machines may provide fundamental knowledge to guide molecular therapeutics and the bottom-up design of nanomaterials and nanodevices. Here, high-speed atomic force microscopy is used to visualize self-assembly of the bidimensional lattice of protein molecules that constitutes the framework of the mature human immunodeficiency virus capsid. By real-time imaging of the assembly reaction, individual transient intermediates and reaction pathways followed by single molecules could be revealed. As when assembling a jigsaw puzzle, the capsid protein lattice is randomly built. Lattice patches grow independently from separate nucleation events whereby individual molecules follow different paths. Protein subunits can be added individually, while others form oligomers before joining a lattice or are occasionally removed from the latter. Direct real-time imaging of supramolecular self-assembly has revealed a complex, chaotic process involving multiple routes followed by individual molecules that are inaccessible to bulk (averaging) techniques.
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Affiliation(s)
- Alejandro Valbuena
- Centro
de Biología Molecular “Severo Ochoa”, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
| | - Sourav Maity
- Moleculaire
Biofysica, Zernike Instituut, Rijksuniversiteit
Groningen, 9712 CP Groningen, The Netherlands
| | - Mauricio G. Mateu
- Centro
de Biología Molecular “Severo Ochoa”, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
| | - Wouter H. Roos
- Moleculaire
Biofysica, Zernike Instituut, Rijksuniversiteit
Groningen, 9712 CP Groningen, The Netherlands
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14
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Summers BJ, Digianantonio KM, Smaga SS, Huang PT, Zhou K, Gerber EE, Wang W, Xiong Y. Modular HIV-1 Capsid Assemblies Reveal Diverse Host-Capsid Recognition Mechanisms. Cell Host Microbe 2019; 26:203-216.e6. [PMID: 31415753 DOI: 10.1016/j.chom.2019.07.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2019] [Revised: 04/21/2019] [Accepted: 07/18/2019] [Indexed: 10/26/2022]
Abstract
The HIV-1 capsid is an ordered protein shell that houses the viral genome during early infection. Its expansive surface consists of an ordered and interfacing array of capsid protein hexamers and pentamers that are recognized by numerous cellular proteins. Many of these proteins recognize specific, assembled capsid interfaces not present in unassembled capsid subunits. We used protein-engineering tools to capture diverse capsid assembly intermediates. We built a repertoire of capsid assemblies (ranging from two to 42 capsid protein molecules) that recreate the various surfaces in infectious capsids. These assemblies reveal unique capsid-targeting mechanisms for each of the anti-HIV factors, TRIMCyp, MxB, and TRIM5α, linked to inhibition of virus uncoating and nuclear entry, as well as the HIV-1 cofactor FEZ1 that facilitates virus intracellular trafficking. This capsid assembly repertoire enables elucidation of capsid recognition modes by known capsid-interacting factors, identification of new capsid-interacting factors, and potentially, development of capsid-targeting therapeutics.
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Affiliation(s)
- Brady J Summers
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | | | - Sarah S Smaga
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Pei-Tzu Huang
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Kaifeng Zhou
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Eva E Gerber
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Wei Wang
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Yong Xiong
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA.
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15
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Wang B, Zhang J, Wu Y. A Multiscale Model for the Self-Assembly of Coat Proteins in Bacteriophage MS2. J Chem Inf Model 2019; 59:3899-3909. [PMID: 31411466 PMCID: PMC7273741 DOI: 10.1021/acs.jcim.9b00514] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The self-assembly of viral capsids is an essential step to the formation of infectious viruses. Elucidating the kinetic mechanisms of how a capsid or virus-like particle assembles could advance our knowledge about the viral lifecycle, as well as the general principles in self-assembly of biomaterials. However, current understanding of capsid assembly remains incomplete for many viruses due to the fact that the transient intermediates along the assembling pathways are experimentally difficult to be detected. In this paper, we constructed a new multiscale computational framework to simulate the self-assembly of virus-like particles. We applied our method to the coat proteins of bacteriophage MS2 as a specific model system. This virus-like particle of bacteriophage MS2 has a unique feature that its 90 sequence-identical dimers can be classified into two structurally various groups: one is the symmetric CC dimer, and the other is the asymmetric AB dimer. The homotypic interactions between AB dimers result in a 5-fold symmetric contact, while the heterotypic interactions between AB and CC dimers result in 6-fold symmetric contact. We found that the assembly can be described as a physical process of phase transition that is regulated by various factors such as concentration and specific stoichiometry between AB and CC dimers. Our simulations also demonstrate that heterotypic and homotypic interfaces play distinctive roles in modulating the assembling kinetics. The interaction between AB and CC dimers is much more dynamic than that between two AB dimers. We therefore suggest that the alternate growth of viral capsid through the heterotypic dimer interactions dominates the assembling pathways. This is, to the best of our knowledge, the first multiscale model to simulate the assembling process of coat proteins in bacteriophage MS2. The generality of this approach opens the door to its further applications in assembly of other viral capsids, virus-like particles, and novel drug delivery systems.
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Affiliation(s)
- Bo Wang
- Department of Systems and Computational Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10461
| | - Junjie Zhang
- Department of Biochemistry and Biophysics, Center for Phage Technology, Texas A&M University, College Station, TX 77843
| | - Yinghao Wu
- Department of Systems and Computational Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10461
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16
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Recent Advances in Coarse-Grained Models for Biomolecules and Their Applications. Int J Mol Sci 2019; 20:ijms20153774. [PMID: 31375023 PMCID: PMC6696403 DOI: 10.3390/ijms20153774] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 07/28/2019] [Accepted: 07/30/2019] [Indexed: 12/23/2022] Open
Abstract
Molecular dynamics simulations have emerged as a powerful tool to study biological systems at varied length and timescales. The conventional all-atom molecular dynamics simulations are being used by the wider scientific community in routine to capture the conformational dynamics and local motions. In addition, recent developments in coarse-grained models have opened the way to study the macromolecular complexes for time scales up to milliseconds. In this review, we have discussed the principle, applicability and recent development in coarse-grained models for biological systems. The potential of coarse-grained simulation has been reviewed through state-of-the-art examples of protein folding and structure prediction, self-assembly of complexes, membrane systems and carbohydrates fiber models. The multiscale simulation approaches have also been discussed in the context of their emerging role in unravelling hierarchical level information of biosystems. We conclude this review with the future scope of coarse-grained simulations as a constantly evolving tool to capture the dynamics of biosystems.
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17
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Pak AJ, Grime JMA, Yu A, Voth GA. Off-Pathway Assembly: A Broad-Spectrum Mechanism of Action for Drugs That Undermine Controlled HIV-1 Viral Capsid Formation. J Am Chem Soc 2019; 141:10214-10224. [PMID: 31244184 PMCID: PMC6739737 DOI: 10.1021/jacs.9b01413] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Indexed: 12/21/2022]
Abstract
The early and late stages of human immunodeficiency virus (HIV) replication are orchestrated by the capsid (CA) protein, which self-assembles into a conical protein shell during viral maturation. Small molecule drugs known as capsid inhibitors (CIs) impede the highly regulated activity of CA. Intriguingly, a few CIs, such as PF-3450074 (PF74) and GS-CA1, exhibit effects at multiple stages of the viral lifecycle at effective concentrations in the pM to nM regimes, while the majority of CIs target a single stage of the viral lifecycle and are effective at nM to μM concentrations. In this work, we use coarse-grained molecular dynamics simulations to elucidate the molecular mechanisms that enable CIs to have such curious broad-spectrum activity. Our quantitatively analyzed findings show that CIs can have a profound impact on the hierarchical self-assembly of CA by perturbing populations of small CA oligomers. The self-assembly process is accelerated by the emergence of alternative assembly pathways that favor the rapid incorporation of CA pentamers, and leads to increased structural pleomorphism in mature capsids. Two relevant phenotypes are observed: (1) eccentric capsid formation that may fail to encase the viral genome and (2) rapid disassembly of the capsid, which express at late and early stages of infection, respectively. Finally, our study emphasizes the importance of adopting a dynamical perspective on inhibitory mechanisms and provides a basis for the design of future therapeutics that are effective at low stoichiometric ratios of drug to protein.
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Affiliation(s)
- Alexander J. Pak
- Department of Chemistry, Institute for Biophysical Dynamics,
and James Franck Institute, The University
of Chicago, Chicago, Illinois 60637, United States
| | - John M. A. Grime
- Department of Chemistry, Institute for Biophysical Dynamics,
and James Franck Institute, The University
of Chicago, Chicago, Illinois 60637, United States
| | - Alvin Yu
- Department of Chemistry, Institute for Biophysical Dynamics,
and James Franck Institute, The University
of Chicago, Chicago, Illinois 60637, United States
| | - Gregory A. Voth
- Department of Chemistry, Institute for Biophysical Dynamics,
and James Franck Institute, The University
of Chicago, Chicago, Illinois 60637, United States
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18
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Goodsell DS, Jewett A, Olson AJ, Forli S. Integrative modeling of the HIV-1 ribonucleoprotein complex. PLoS Comput Biol 2019; 15:e1007150. [PMID: 31194731 PMCID: PMC6592547 DOI: 10.1371/journal.pcbi.1007150] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 06/25/2019] [Accepted: 05/31/2019] [Indexed: 12/22/2022] Open
Abstract
A coarse-grain computational method integrates biophysical and structural data to generate models of HIV-1 genomic RNA, nucleocapsid and integrase condensed into a mature ribonucleoprotein complex. Several hypotheses for the initial structure of the genomic RNA and oligomeric state of integrase are tested. In these models, integrase interaction captures features of the relative distribution of gRNA in the immature virion and increases the size of the RNP globule, and exclusion of nucleocapsid from regions with RNA secondary structure drives an asymmetric placement of the dimerized 5’UTR at the surface of the RNP globule. The genome of HIV-1 is composed of two strands of RNA that are packaged in the mature virion as a condensed ribonucleoprotein complex with nucleocapsid, integrase, and other proteins. We have generated models of the HIV-1 ribonucleoprotein that integrate experimental results from multiple structural and biophysical experiments, exploring several hypotheses about the state of the RNA before condensation, and the role of crosslinking by integrase. The models suggest that the 5’UTR, which shows extensive secondary structure, has a propensity to be placed on the surface of the condensed globule, due to reduced binding of nucleocapsid to double-stranded regions within the 5’UTR. This unexpected localization of the 5’UTR may have consequences for the subsequent structural transitions that occur during the process of reverse transcription.
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Affiliation(s)
- David S. Goodsell
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, United States of America
- Center for Integrative Proteomics Research, Rutgers State University, Piscataway, New Jersey, United States of America
- * E-mail:
| | - Andrew Jewett
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Arthur J. Olson
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Stefano Forli
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, United States of America
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19
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Jin J, Han Y, Voth GA. Coarse-graining involving virtual sites: Centers of symmetry coarse-graining. J Chem Phys 2019; 150:154103. [DOI: 10.1063/1.5067274] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Affiliation(s)
- Jaehyeok Jin
- Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, USA
| | - Yining Han
- Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, USA
| | - Gregory A. Voth
- Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, USA
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20
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Sharp ME, Vázquez FX, Wagner JW, Dannenhoffer-Lafage T, Voth GA. Multiconfigurational Coarse-Grained Molecular Dynamics. J Chem Theory Comput 2019; 15:3306-3315. [PMID: 30897328 PMCID: PMC6660024 DOI: 10.1021/acs.jctc.8b01133] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
![]()
Standard low resolution
coarse-grained modeling techniques have difficulty capturing multiple
configurations of protein systems. Here, we present a method for creating
accurate coarse-grained (CG) models with multiple configurations using
a linear combination of functions or “states”. Individual
CG models are created to capture the individual states, and the approximate
coupling between the two states is determined from an all-atom potential
of mean force. We show that the resulting multiconfiguration coarse-graining
(MCCG) method accurately captures the transition state as well as
the free energy between the two states. We have tested this method
on the folding of dodecaalanine, as well as the amphipathic helix
of endophilin.
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Affiliation(s)
- Morris E Sharp
- Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics , The University of Chicago , Chicago , Illinois 60637 , United States
| | - Francisco X Vázquez
- Department of Chemistry , St. John's University , Queens , New York 11439 , United States
| | - Jacob W Wagner
- Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics , The University of Chicago , Chicago , Illinois 60637 , United States
| | - Thomas Dannenhoffer-Lafage
- Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics , The University of Chicago , Chicago , Illinois 60637 , United States
| | - Gregory A Voth
- Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics , The University of Chicago , Chicago , Illinois 60637 , United States
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21
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Jefferys EE, Sansom MSP. Computational Virology: Molecular Simulations of Virus Dynamics and Interactions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1215:201-233. [DOI: 10.1007/978-3-030-14741-9_10] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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22
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Advances in coarse-grained modeling of macromolecular complexes. Curr Opin Struct Biol 2018; 52:119-126. [PMID: 30508766 DOI: 10.1016/j.sbi.2018.11.005] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 11/05/2018] [Accepted: 11/17/2018] [Indexed: 01/12/2023]
Abstract
Recent progress in coarse-grained (CG) molecular modeling and simulation has facilitated an influx of computational studies on biological macromolecules and their complexes. Given the large separation of length-scales and time-scales that dictate macromolecular biophysics, CG modeling and simulation are well-suited to bridge the microscopic and mesoscopic or macroscopic details observed from all-atom molecular simulations and experiments, respectively. In this review, we first summarize recent innovations in the development of CG models, which broadly include structure-based, knowledge-based, and dynamics-based approaches. We then discuss recent applications of different classes of CG models to explore various macromolecular complexes. Finally, we conclude with an outlook for the future in this ever-growing field of biomolecular modeling.
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23
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Johnson ME. Modeling the Self-Assembly of Protein Complexes through a Rigid-Body Rotational Reaction-Diffusion Algorithm. J Phys Chem B 2018; 122:11771-11783. [PMID: 30256109 DOI: 10.1021/acs.jpcb.8b08339] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The reaction-diffusion equations provide a powerful framework for modeling nonequilibrium, cell-scale dynamics over the long time scales that are inaccessible by traditional molecular modeling approaches. Single-particle reaction-diffusion offers the highest resolution technique for tracking such dynamics, but it has not been applied to the study of protein self-assembly due to its treatment of reactive species as single-point particles. Here, we develop a relatively simple but accurate approach for building rigid structure and rotation into single-particle reaction-diffusion methods, providing a rate-based method for studying protein self-assembly. Our simplifying assumption is that reactive collisions can be evaluated purely on the basis of the separations between the sites, and not their orientations. The challenge of evaluating reaction probabilities can then be performed using well-known equations based on translational diffusion in both 3D and 2D, by employing an effective diffusion constant we derive here. We show how our approach reproduces both the kinetics of association, which is altered by rotational diffusion, and the equilibrium of reversible association, which is not. Importantly, the macroscopic kinetics of association can be predicted on the basis of the microscopic parameters of our structurally resolved model, allowing for critical comparisons with theory and other rate-based simulations. We demonstrate this method for efficient, rate-based simulations of self-assembly of clathrin trimers, highlighting how formation of regular lattices impacts the kinetics of association.
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Affiliation(s)
- Margaret E Johnson
- TC Jenkins Department of Biophysics , The Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States
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24
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Sharma KK, Marzinek JK, Tantirimudalige SN, Bond PJ, Wohland T. Single-molecule studies of flavivirus envelope dynamics: Experiment and computation. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2018; 143:38-51. [PMID: 30223001 DOI: 10.1016/j.pbiomolbio.2018.09.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 09/06/2018] [Accepted: 09/11/2018] [Indexed: 12/11/2022]
Abstract
Flaviviruses are simple enveloped viruses exhibiting complex structural and functional heterogeneities. Decades of research have provided crucial basic insights, antiviral medication and moderately successful gene therapy trials. The most infectious particle is, however, not always the most abundant one in a population, questioning the utility of classic ensemble-averaging virology approaches. Indeed, viral replication is often not particularly efficient, prone to errors or containing parallel routes. Here, we review different single-molecule sensitive fluorescence methods that are employed to investigate flaviviruses. In particular, we review how (i) time-resolved Förster resonance energy transfer (trFRET) was applied to probe dengue envelope conformations; (ii) FRET-fluorescence correlation spectroscopy to investigate dengue envelope intrinsic dynamics and (iii) single particle tracking to follow the path of dengue viruses in cells. We also discuss how such methods may be supported by molecular dynamics (MD) simulations over a range of spatio-temporal scales, to provide complementary data on the structure and dynamics of flaviviral systems. We describe recent improvements in multiscale MD approaches that allowed the simulation of dengue particle envelopes in near-atomic resolution. We hope this review is an incentive for setting up and applying similar single-molecule studies and combine them with MD simulations to investigate structural dynamics of entire flavivirus particles over the nanosecond-to-millisecond time-scale and follow viruses during infection in cells over milliseconds to minutes.
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Affiliation(s)
- Kamal Kant Sharma
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
| | - Jan K Marzinek
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore; Bioinformatics Institute (A*STAR), 30 Biopolis Street, #07-01 Matrix, Singapore 138671, Singapore
| | - Sarala Neomi Tantirimudalige
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
| | - Peter J Bond
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore; Bioinformatics Institute (A*STAR), 30 Biopolis Street, #07-01 Matrix, Singapore 138671, Singapore.
| | - Thorsten Wohland
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore; Department of Chemistry, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore; Centre for Bioimaging Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117557, Singapore.
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25
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Hadden JA, Perilla JR, Schlicksup CJ, Venkatakrishnan B, Zlotnick A, Schulten K. All-atom molecular dynamics of the HBV capsid reveals insights into biological function and cryo-EM resolution limits. eLife 2018; 7:32478. [PMID: 29708495 PMCID: PMC5927769 DOI: 10.7554/elife.32478] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 04/05/2018] [Indexed: 12/11/2022] Open
Abstract
The hepatitis B virus capsid represents a promising therapeutic target. Experiments suggest the capsid must be flexible to function; however, capsid structure and dynamics have not been thoroughly characterized in the absence of icosahedral symmetry constraints. Here, all-atom molecular dynamics simulations are leveraged to investigate the capsid without symmetry bias, enabling study of capsid flexibility and its implications for biological function and cryo-EM resolution limits. Simulation results confirm flexibility and reveal a propensity for asymmetric distortion. The capsid’s influence on ionic species suggests a mechanism for modulating the display of cellular signals and implicates the capsid’s triangular pores as the location of signal exposure. A theoretical image reconstruction performed using simulated conformations indicates how capsid flexibility may limit the resolution of cryo-EM. Overall, the present work provides functional insight beyond what is accessible to experimental methods and raises important considerations regarding asymmetry in structural studies of icosahedral virus capsids.
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Affiliation(s)
- Jodi A Hadden
- Department of Chemistry and Biochemistry, University of Delaware, Newark, United States
| | - Juan R Perilla
- Department of Chemistry and Biochemistry, University of Delaware, Newark, United States
| | | | | | - Adam Zlotnick
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, United States
| | - Klaus Schulten
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, United States.,Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, United States
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26
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Tomasini MD, Johnson DS, Mincer JS, Simon SM. Modeling the dynamics and kinetics of HIV-1 Gag during viral assembly. PLoS One 2018; 13:e0196133. [PMID: 29677208 PMCID: PMC5909904 DOI: 10.1371/journal.pone.0196133] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 04/07/2018] [Indexed: 12/24/2022] Open
Abstract
We report a computational model for the assembly of HIV-1 Gag into immature viral particles at the plasma membrane. To reproduce experimental structural and kinetic properties of assembly, a process occurring on the order of minutes, a coarse-grained representation consisting of a single particle per Gag molecule is developed. The model uses information relating the functional interfaces implicated in Gag assembly, results from cryo electron-tomography, and biophysical measurements from fluorescence microscopy, such as the dynamics of Gag assembly at single virions. These experimental constraints eliminated many classes of potential interactions, and narrowed the model to a single interaction scheme with two non-equivalent interfaces acting to form Gags into a hexamer, and a third interface acting to link hexamers together. This model was able to form into a hexameric structure with correct lattice spacing and reproduced biologically relevant growth rates. We explored the effect of genomic RNA seeding punctum growth, finding that RNA may be a factor in locally concentrating Gags to initiate assembly. The simulation results infer that completion of assembly cannot be governed simply by Gag binding kinetics. However the addition of membrane curvature suggests that budding of the virion from the plasma membrane could factor into slowing incorporation of Gag at an assembly site resulting in virions of the same size and number of Gag molecules independent of Gag concentration or the time taken to complete assembly. To corroborate the results of our simulation model, we developed an analytic model for Gag assembly finding good agreement with the simulation results.
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Affiliation(s)
- Michael D. Tomasini
- Laboratory of Cellular Biophysics, Rockefeller University, New York, New York, United States of America
| | - Daniel S. Johnson
- Laboratory of Cellular Biophysics, Rockefeller University, New York, New York, United States of America
- Department of Physics and Astronomy, Hofstra University, 151 Hofstra University, Hempstead, New York, United States of America
| | - Joshua S. Mincer
- Laboratory of Cellular Biophysics, Rockefeller University, New York, New York, United States of America
- Department of Anesthesiology, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Sanford M. Simon
- Laboratory of Cellular Biophysics, Rockefeller University, New York, New York, United States of America
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27
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Bore SL, Milano G, Cascella M. Hybrid Particle-Field Model for Conformational Dynamics of Peptide Chains. J Chem Theory Comput 2018; 14:1120-1130. [DOI: 10.1021/acs.jctc.7b01160] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Sigbjørn Løland Bore
- Department
of Chemistry and Hylleraas Centre for Quantum Molecular Sciences, University of Oslo, P.O.
Box 1033 Blindern, 0315 Oslo, Norway
| | - Giuseppe Milano
- Department
of Organic Materials Science, University of Yamagata, 4-3-16 Jonan
Yonezawa, Yamagata-ken 992-8510, Japan
| | - Michele Cascella
- Department
of Chemistry and Hylleraas Centre for Quantum Molecular Sciences, University of Oslo, P.O.
Box 1033 Blindern, 0315 Oslo, Norway
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28
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Immature HIV-1 lattice assembly dynamics are regulated by scaffolding from nucleic acid and the plasma membrane. Proc Natl Acad Sci U S A 2017; 114:E10056-E10065. [PMID: 29114055 DOI: 10.1073/pnas.1706600114] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The packaging and budding of Gag polyprotein and viral RNA is a critical step in the HIV-1 life cycle. High-resolution structures of the Gag polyprotein have revealed that the capsid (CA) and spacer peptide 1 (SP1) domains contain important interfaces for Gag self-assembly. However, the molecular details of the multimerization process, especially in the presence of RNA and the cell membrane, have remained unclear. In this work, we investigate the mechanisms that work in concert between the polyproteins, RNA, and membrane to promote immature lattice growth. We develop a coarse-grained (CG) computational model that is derived from subnanometer resolution structural data. Our simulations recapitulate contiguous and hexameric lattice assembly driven only by weak anisotropic attractions at the helical CA-SP1 junction. Importantly, analysis from CG and single-particle tracking photoactivated localization (spt-PALM) trajectories indicates that viral RNA and the membrane are critical constituents that actively promote Gag multimerization through scaffolding, while overexpression of short competitor RNA can suppress assembly. We also find that the CA amino-terminal domain imparts intrinsic curvature to the Gag lattice. As a consequence, immature lattice growth appears to be coupled to the dynamics of spontaneous membrane deformation. Our findings elucidate a simple network of interactions that regulate the early stages of HIV-1 assembly and budding.
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29
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Huber RG, Marzinek JK, Holdbrook DA, Bond PJ. Multiscale molecular dynamics simulation approaches to the structure and dynamics of viruses. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017; 128:121-132. [DOI: 10.1016/j.pbiomolbio.2016.09.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 09/06/2016] [Accepted: 09/27/2016] [Indexed: 12/15/2022]
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30
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Biswal D, Kusalik PG. Molecular simulations of self-assembly processes in metal-organic frameworks: Model dependence. J Chem Phys 2017; 147:044702. [PMID: 28764378 DOI: 10.1063/1.4994700] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Molecular simulation is a powerful tool for investigating microscopic behavior in various chemical systems, where the use of suitable models is critical to successfully reproduce the structural and dynamic properties of the real systems of interest. In this context, molecular dynamics simulation studies of self-assembly processes in metal-organic frameworks (MOFs), a well-known class of porous materials with interesting chemical and physical properties, are relatively challenging, where a reasonably accurate representation of metal-ligand interactions is anticipated to play an important role. In the current study, we both investigate the performance of some existing models and introduce and test new models to help explore the self-assembly in an archetypal Zn-carboxylate MOF system. To this end, the behavior of six different Zn-ion models, three solvent models, and two ligand models was examined and validated against key experimental structural parameters. To explore longer time scale ordering events during MOF self-assembly via explicit solvent simulations, it is necessary to identify a suitable combination of simplified model components representing metal ions, organic ligands, and solvent molecules. It was observed that an extended cationic dummy atom (ECDA) Zn-ion model combined with an all-atom carboxylate ligand model and a simple dipolar solvent model can reproduce characteristic experimental structures for the archetypal MOF system. The successful use of these models in extensive sets of molecular simulations, which provide key insights into the self-assembly mechanism of this archetypal MOF system occurring during the early stages of this process, has been very recently reported.
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Affiliation(s)
- Debasmita Biswal
- Department of Chemistry, University of Calgary, 2500 University Dr. NW, Calgary, Alberta T2N 1N4, Canada
| | - Peter G Kusalik
- Department of Chemistry, University of Calgary, 2500 University Dr. NW, Calgary, Alberta T2N 1N4, Canada
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31
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Miyazaki Y, Miyake A, Doi N, Koma T, Uchiyama T, Adachi A, Nomaguchi M. Comparison of Biochemical Properties of HIV-1 and HIV-2 Capsid Proteins. Front Microbiol 2017; 8:1082. [PMID: 28659897 PMCID: PMC5469281 DOI: 10.3389/fmicb.2017.01082] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 05/29/2017] [Indexed: 01/08/2023] Open
Abstract
Timely disassembly of viral core composed of self-assembled capsid (CA) in infected host cells is crucial for retroviral replication. Extensive in vitro studies to date on the self-assembly/disassembly mechanism of human immunodeficiency virus type 1 (HIV-1) CA have revealed its core structure and amino acid residues essential for CA–CA intermolecular interaction. However, little is known about in vitro properties of HIV-2 CA. In this study, we comparatively analyzed the polymerization properties of bacterially expressed HIV-1 and HIV-2 CA proteins. Interestingly, a much higher concentration of NaCl was required for HIV-2 CA to self-assemble than that for HIV-1 CA, but once the polymerization started, the reaction proceeded more rapidly than that observed for HIV-1 CA. Analysis of a chimeric protein revealed that N-terminal domain (NTD) is responsible for this unique property of HIV-2 CA. To further study the molecular basis for different in vitro properties of HIV-1 and HIV-2 CA proteins, we determined thermal stabilities of HIV-1 and HIV-2 CA NTD proteins at several NaCl concentrations by fluorescent-based thermal shift assays. Experimental data obtained showed that HIV-2 CA NTD was structurally more stable than HIV-1 CA NTD. Taken together, our results imply that distinct in vitro polymerization abilities of the two CA proteins are related to their structural instability/stability, which is one of the decisive factors for viral replication potential. In addition, our assay system described here may be potentially useful for searching for anti-CA antivirals against HIV-1 and HIV-2.
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Affiliation(s)
- Yasuyuki Miyazaki
- Department of Microbiology and Cell Biology, Tokyo Metropolitan Institute of Medical ScienceTokyo, Japan
| | - Ariko Miyake
- Laboratory of Molecular Immunology and Infectious Disease, Joint Faculty of Veterinary Medicine, Yamaguchi UniversityYamaguchi, Japan
| | - Noya Doi
- Department of Microbiology, Tokushima University Graduate School of Medical SciencesTokushima, Japan
| | - Takaaki Koma
- Department of Microbiology, Tokushima University Graduate School of Medical SciencesTokushima, Japan
| | - Tsuneo Uchiyama
- Department of Microbiology, Tokushima University Graduate School of Medical SciencesTokushima, Japan
| | - Akio Adachi
- Department of Microbiology, Tokushima University Graduate School of Medical SciencesTokushima, Japan
| | - Masako Nomaguchi
- Department of Microbiology, Tokushima University Graduate School of Medical SciencesTokushima, Japan
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32
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Sha H, Zhu F. Parameter Optimization for Interaction between C-Terminal Domains of HIV-1 Capsid Protein. J Chem Inf Model 2017; 57:1134-1141. [PMID: 28426204 DOI: 10.1021/acs.jcim.7b00011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
HIV-1 capsid proteins (CAs) assemble into a capsid that encloses the viral RNA. The binding between a pair of C-terminal domains (CTDs) constitutes a major interface in both the CA dimers and the large CA assemblies. Here, we attempt to use a general residue-level coarse-grained model to describe the interaction between two isolated CTDs in Monte Carlo simulations. With the standard parameters that depend only on the residue types, the model predicts a much weaker binding in comparison to the experiments. Detailed analysis reveals that some Lennard-Jones parameters are not compatible with the experimental CTD dimer structure, thus resulting in an unfavorable interaction energy. To improve the model for the CTD binding, we introduce ad hoc modifications to a small number of Lennard-Jones parameters for some specific pairs of residues at the binding interface. Through a series of extensive Monte Carlo simulations, we identify the optimal parameters for the CTD-CTD interactions. With the refined model parameters, both the binding affinity (with a dissociation constant of 13 ± 2 μM) and the binding mode are in good agreement with the experimental data. This study demonstrates that the general interaction model based on the Lennard-Jones potential, with some modest adjustment of the parameters for key residues, could correctly reproduce the reversible protein binding, thus potentially applicable for simulating the thermodynamics of the CA assemblies.
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Affiliation(s)
- Hao Sha
- Department of Physics, Indiana University - Purdue University Indianapolis , 402 N. Blackford, LD 154, Indianapolis, Indiana 46202, United States
| | - Fangqiang Zhu
- Department of Physics, Indiana University - Purdue University Indianapolis , 402 N. Blackford, LD 154, Indianapolis, Indiana 46202, United States
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33
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Jeon J, Qiao X, Hung I, Mitra AK, Desfosses A, Huang D, Gor’kov PL, Craven RC, Kingston RL, Gan Z, Zhu F, Chen B. Structural Model of the Tubular Assembly of the Rous Sarcoma Virus Capsid Protein. J Am Chem Soc 2017; 139:2006-2013. [DOI: 10.1021/jacs.6b11939] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Jaekyun Jeon
- Department
of Physics, University of Central Florida, Orlando, Florida 32816, United States
| | - Xin Qiao
- Department
of Physics, University of Central Florida, Orlando, Florida 32816, United States
| | - Ivan Hung
- National
High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
| | - Alok K. Mitra
- School
of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Ambroise Desfosses
- School
of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Daniel Huang
- Department
of Physics, University of Central Florida, Orlando, Florida 32816, United States
| | - Peter L. Gor’kov
- National
High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
| | - Rebecca C. Craven
- Department
of Microbiology and Immunology, Penn State University College of Medicine, Hershey, Pennsylvania 17033, United States
| | - Richard L. Kingston
- School
of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Zhehong Gan
- National
High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
| | - Fangqiang Zhu
- Department
of Physics, Indiana University−Purdue University Indianapolis, Indianapolis, Indiana 46202, United States
| | - Bo Chen
- Department
of Physics, University of Central Florida, Orlando, Florida 32816, United States
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34
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Ning J, Erdemci-Tandogan G, Yufenyuy EL, Wagner J, Himes BA, Zhao G, Aiken C, Zandi R, Zhang P. In vitro protease cleavage and computer simulations reveal the HIV-1 capsid maturation pathway. Nat Commun 2016; 7:13689. [PMID: 27958264 PMCID: PMC5159922 DOI: 10.1038/ncomms13689] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 10/24/2016] [Indexed: 12/23/2022] Open
Abstract
HIV-1 virions assemble as immature particles containing Gag polyproteins that are processed by the viral protease into individual components, resulting in the formation of mature infectious particles. There are two competing models for the process of forming the mature HIV-1 core: the disassembly and de novo reassembly model and the non-diffusional displacive model. To study the maturation pathway, we simulate HIV-1 maturation in vitro by digesting immature particles and assembled virus-like particles with recombinant HIV-1 protease and monitor the process with biochemical assays and cryoEM structural analysis in parallel. Processing of Gag in vitro is accurate and efficient and results in both soluble capsid protein and conical or tubular capsid assemblies, seemingly converted from immature Gag particles. Computer simulations further reveal probable assembly pathways of HIV-1 capsid formation. Combining the experimental data and computer simulations, our results suggest a sequential combination of both displacive and disassembly/reassembly processes for HIV-1 maturation. Two competing models—disassembly/reassembly and displacive—have been proposed for how immature spherical HIV virions transform into mature particles with conical cores. Here the authors provide evidence that both disassembly/reassembly and displacive processes occur sequentially during the maturation process.
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Affiliation(s)
- Jiying Ning
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 5th Avenue, Pittsburgh, Pennsylvania 15260, USA.,Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260, USA
| | - Gonca Erdemci-Tandogan
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - Ernest L Yufenyuy
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
| | - Jef Wagner
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - Benjamin A Himes
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 5th Avenue, Pittsburgh, Pennsylvania 15260, USA
| | - Gongpu Zhao
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 5th Avenue, Pittsburgh, Pennsylvania 15260, USA.,Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260, USA
| | - Christopher Aiken
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260, USA.,Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
| | - Roya Zandi
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - Peijun Zhang
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 5th Avenue, Pittsburgh, Pennsylvania 15260, USA.,Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260, USA.,Division of Structural Biology, University of Oxford, The Henry Wellcome Building for Genomic Medicine, Headington, Oxford OX3 7BN, UK.,Electron Bio-Imaging Centre, Diamond Light Sources, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
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35
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Sadiq SK. Reaction-diffusion basis of retroviral infectivity. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2016; 374:rsta.2016.0148. [PMID: 27698042 PMCID: PMC5052732 DOI: 10.1098/rsta.2016.0148] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/22/2016] [Indexed: 05/27/2023]
Abstract
Retrovirus particle (virion) infectivity requires diffusion and clustering of multiple transmembrane envelope proteins (Env3) on the virion exterior, yet is triggered by protease-dependent degradation of a partially occluding, membrane-bound Gag polyprotein lattice on the virion interior. The physical mechanism underlying such coupling is unclear and only indirectly accessible via experiment. Modelling stands to provide insight but the required spatio-temporal range far exceeds current accessibility by all-atom or even coarse-grained molecular dynamics simulations. Nor do such approaches account for chemical reactions, while conversely, reaction kinetics approaches handle neither diffusion nor clustering. Here, a recently developed multiscale approach is considered that applies an ultra-coarse-graining scheme to treat entire proteins at near-single particle resolution, but which also couples chemical reactions with diffusion and interactions. A model is developed of Env3 molecules embedded in a truncated Gag lattice composed of membrane-bound matrix proteins linked to capsid subunits, with freely diffusing protease molecules. Simulations suggest that in the presence of Gag but in the absence of lateral lattice-forming interactions, Env3 diffuses comparably to Gag-absent Env3 Initial immobility of Env3 is conferred through lateral caging by matrix trimers vertically coupled to the underlying hexameric capsid layer. Gag cleavage by protease vertically decouples the matrix and capsid layers, induces both matrix and Env3 diffusion, and permits Env3 clustering. Spreading across the entire membrane surface reduces crowding, in turn, enhancing the effect and promoting infectivity.This article is part of the themed issue 'Multiscale modelling at the physics-chemistry-biology interface'.
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Affiliation(s)
- S Kashif Sadiq
- Infection Biology Unit, Universitat Pompeu Fabra, Barcelona Biomedical Research Park (PRBB), C/Doctor Aiguader 88, 08003 Barcelona, Spain Molecular and Cellular Modeling Group, Heidelberg Institute for Theoretical Studies (HITS), Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany
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36
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Chavent M, Duncan AL, Sansom MS. Molecular dynamics simulations of membrane proteins and their interactions: from nanoscale to mesoscale. Curr Opin Struct Biol 2016; 40:8-16. [PMID: 27341016 PMCID: PMC5404110 DOI: 10.1016/j.sbi.2016.06.007] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2016] [Revised: 06/06/2016] [Accepted: 06/07/2016] [Indexed: 11/21/2022]
Abstract
Molecular dynamics simulations provide a computational tool to probe membrane proteins and systems at length scales ranging from nanometers to close to a micrometer, and on microsecond timescales. All atom and coarse-grained simulations may be used to explore in detail the interactions of membrane proteins and specific lipids, yielding predictions of lipid binding sites in good agreement with available structural data. Building on the success of protein-lipid interaction simulations, larger scale simulations reveal crowding and clustering of proteins, resulting in slow and anomalous diffusional dynamics, within realistic models of cell membranes. Current methods allow near atomic resolution simulations of small membrane organelles, and of enveloped viruses to be performed, revealing key aspects of their structure and functionally important dynamics.
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Affiliation(s)
- Matthieu Chavent
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Anna L Duncan
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Mark Sp Sansom
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
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37
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Reddy T, Sansom MSP. Computational virology: From the inside out. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1858:1610-8. [PMID: 26874202 PMCID: PMC4884666 DOI: 10.1016/j.bbamem.2016.02.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 02/05/2016] [Accepted: 02/08/2016] [Indexed: 12/23/2022]
Abstract
Viruses typically pack their genetic material within a protein capsid. Enveloped viruses also have an outer membrane made up of a lipid bilayer and membrane-spanning glycoproteins. X-ray diffraction and cryoelectron microscopy provide high resolution static views of viral structure. Molecular dynamics (MD) simulations may be used to provide dynamic insights into the structures of viruses and their components. There have been a number of simulations of viral capsids and (in some cases) of the inner core of RNA or DNA packaged within them. These simulations have generally focussed on the structural integrity and stability of the capsid and/or on the influence of the nucleic acid core on capsid stability. More recently there have been a number of simulation studies of enveloped viruses, including HIV-1, influenza A, and dengue virus. These have addressed the dynamic behaviour of the capsid, the matrix, and/or of the outer envelope. Analysis of the dynamics of the lipid bilayer components of the envelopes of influenza A and of dengue virus reveals a degree of biophysical robustness, which may contribute to the stability of virus particles in different environments. Significant computational challenges need to be addressed to aid simulation of complex viruses and their membranes, including the need to integrate structural data from a range of sources to enable us to move towards simulations of intact virions. This article is part of a Special Issue entitled: Membrane Proteins edited by J.C. Gumbart and Sergei Noskov.
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Affiliation(s)
- Tyler Reddy
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
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38
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Smith GR, Xie L, Schwartz R. Modeling Effects of RNA on Capsid Assembly Pathways via Coarse-Grained Stochastic Simulation. PLoS One 2016; 11:e0156547. [PMID: 27244559 PMCID: PMC4887116 DOI: 10.1371/journal.pone.0156547] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2015] [Accepted: 05/16/2016] [Indexed: 12/02/2022] Open
Abstract
The environment of a living cell is vastly different from that of an in vitro reaction system, an issue that presents great challenges to the use of in vitro models, or computer simulations based on them, for understanding biochemistry in vivo. Virus capsids make an excellent model system for such questions because they typically have few distinct components, making them amenable to in vitro and modeling studies, yet their assembly can involve complex networks of possible reactions that cannot be resolved in detail by any current experimental technology. We previously fit kinetic simulation parameters to bulk in vitro assembly data to yield a close match between simulated and real data, and then used the simulations to study features of assembly that cannot be monitored experimentally. The present work seeks to project how assembly in these simulations fit to in vitro data would be altered by computationally adding features of the cellular environment to the system, specifically the presence of nucleic acid about which many capsids assemble. The major challenge of such work is computational: simulating fine-scale assembly pathways on the scale and in the parameter domains of real viruses is far too computationally costly to allow for explicit models of nucleic acid interaction. We bypass that limitation by applying analytical models of nucleic acid effects to adjust kinetic rate parameters learned from in vitro data to see how these adjustments, singly or in combination, might affect fine-scale assembly progress. The resulting simulations exhibit surprising behavioral complexity, with distinct effects often acting synergistically to drive efficient assembly and alter pathways relative to the in vitro model. The work demonstrates how computer simulations can help us understand how assembly might differ between the in vitro and in vivo environments and what features of the cellular environment account for these differences.
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Affiliation(s)
- Gregory R. Smith
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Lu Xie
- Joint Carnegie Mellon/University of Pittsburgh Ph.D. Program in Computational Biology, Pittsburgh, Pennsylvania, United States of America
- Computational Biology Department, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Russell Schwartz
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
- Computational Biology Department, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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39
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Grime JMA, Dama JF, Ganser-Pornillos BK, Woodward CL, Jensen GJ, Yeager M, Voth GA. Coarse-grained simulation reveals key features of HIV-1 capsid self-assembly. Nat Commun 2016; 7:11568. [PMID: 27174390 PMCID: PMC4869257 DOI: 10.1038/ncomms11568] [Citation(s) in RCA: 115] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 04/07/2016] [Indexed: 12/23/2022] Open
Abstract
The maturation of HIV-1 viral particles is essential for viral infectivity. During maturation, many copies of the capsid protein (CA) self-assemble into a capsid shell to enclose the viral RNA. The mechanistic details of the initiation and early stages of capsid assembly remain to be delineated. We present coarse-grained simulations of capsid assembly under various conditions, considering not only capsid lattice self-assembly but also the potential disassembly of capsid upon delivery to the cytoplasm of a target cell. The effects of CA concentration, molecular crowding, and the conformational variability of CA are described, with results indicating that capsid nucleation and growth is a multi-stage process requiring well-defined metastable intermediates. Generation of the mature capsid lattice is sensitive to local conditions, with relatively subtle changes in CA concentration and molecular crowding influencing self-assembly and the ensemble of structural morphologies. Significant morphological changes occur during the conversion of the immature HIV virion into a mature infectious form. Here the authors use coarse-grained molecular dynamics simulations to model HIV-1 capsid self-assembly and disassembly events that suggests several metastable capsid intermediates sensitive to local conditions.
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Affiliation(s)
- John M A Grime
- Department of Chemistry, Institute for Biophysical Dynamics, James Franck Institute, and Computation Institute, The University of Chicago, Chicago, Illinois 60637, USA
| | - James F Dama
- Department of Chemistry, Institute for Biophysical Dynamics, James Franck Institute, and Computation Institute, The University of Chicago, Chicago, Illinois 60637, USA
| | - Barbie K Ganser-Pornillos
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
| | - Cora L Woodward
- Division of Biology, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125, USA
| | - Grant J Jensen
- Division of Biology, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125, USA.,Howard Hughes Medical Institute, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125, USA
| | - Mark Yeager
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.,Center for Membrane Biology, Cardiovascular Research Center, and Division of Cardiovascular Medicine, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
| | - Gregory A Voth
- Department of Chemistry, Institute for Biophysical Dynamics, James Franck Institute, and Computation Institute, The University of Chicago, Chicago, Illinois 60637, USA
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40
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Abstract
The HIV genome materials are encaged by a proteinaceous shell called the capsid, constructed from ∼1000-1500 copies of the capsid proteins. Because its stability and integrity are critical to the normal life cycle and infectivity of the virus, the HIV capsid is a promising antiviral drug target. In this paper, we review the studies shaping our understanding of the structure and dynamics of the capsid proteins and various forms of their assemblies, as well as the assembly mechanism.
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Affiliation(s)
- Bo Chen
- Department of Physics, University of Central Florida , Orlando, Florida 32816, United States
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41
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Lu JX, Bayro MJ, Tycko R. Major Variations in HIV-1 Capsid Assembly Morphologies Involve Minor Variations in Molecular Structures of Structurally Ordered Protein Segments. J Biol Chem 2016; 291:13098-112. [PMID: 27129282 DOI: 10.1074/jbc.m116.720557] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2016] [Indexed: 12/13/2022] Open
Abstract
We present the results of solid state nuclear magnetic resonance (NMR) experiments on HIV-1 capsid protein (CA) assemblies with three different morphologies, namely wild-type CA (WT-CA) tubes with 35-60 nm diameters, planar sheets formed by the Arg(18)-Leu mutant (R18L-CA), and R18L-CA spheres with 20-100 nm diameters. The experiments are intended to elucidate molecular structural variations that underlie these variations in CA assembly morphology. We find that multidimensional solid state NMR spectra of (15)N,(13)C-labeled CA assemblies are remarkably similar for the three morphologies, with only small differences in (15)N and (13)C chemical shifts, no significant differences in NMR line widths, and few differences in the number of detectable NMR cross-peaks. Thus, the pronounced differences in morphology do not involve major differences in the conformations and identities of structurally ordered protein segments. Instead, morphological variations are attributable to variations in conformational distributions within disordered segments, which do not contribute to the solid state NMR spectra. Variations in solid state NMR signals from certain amino acid side chains are also observed, suggesting differences in the intermolecular dimerization interface between curved and planar CA lattices, as well as possible differences in intramolecular helix-helix packing.
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Affiliation(s)
- Jun-Xia Lu
- From the Laboratory of Chemical Physics, NIDKK, National Institutes of Health, Bethesda, Maryland 20892-0520
| | - Marvin J Bayro
- From the Laboratory of Chemical Physics, NIDKK, National Institutes of Health, Bethesda, Maryland 20892-0520
| | - Robert Tycko
- From the Laboratory of Chemical Physics, NIDKK, National Institutes of Health, Bethesda, Maryland 20892-0520
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42
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Hagan MF, Zandi R. Recent advances in coarse-grained modeling of virus assembly. Curr Opin Virol 2016; 18:36-43. [PMID: 27016708 DOI: 10.1016/j.coviro.2016.02.012] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 02/29/2016] [Indexed: 01/08/2023]
Affiliation(s)
- Michael F Hagan
- Martin Fisher School of Physics, Brandeis University, Waltham, MA 02453, USA.
| | - Roya Zandi
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA.
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43
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Sadre-Marandi F, Liu Y, Liu J, Tavener S, Zou X. Modeling HIV-1 viral capsid nucleation by dynamical systems. Math Biosci 2015; 270:95-105. [PMID: 26596714 DOI: 10.1016/j.mbs.2015.10.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 09/08/2015] [Accepted: 10/09/2015] [Indexed: 11/15/2022]
Abstract
There are two stages generally recognized in the viral capsid assembly: nucleation and elongation. This paper focuses on the nucleation stage and develops mathematical models for HIV-1 viral capsid nucleation based on six-species dynamical systems. The Particle Swarm Optimization (PSO) algorithm is used for parameter fitting to estimate the association and dissociation rates from biological experiment data. Numerical simulations of capsid protein (CA) multimer concentrations demonstrate a good agreement with experimental data. Sensitivity and elasticity analysis of CA multimer concentrations with respect to the association and dissociation rates further reveals the importance of CA trimer-of- dimers in the nucleation stage of viral capsid self- assembly.
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Affiliation(s)
- Farrah Sadre-Marandi
- Department of Mathematics, Colorado State University, Fort Collins, CO 80523-1874, USA.
| | - Yuewu Liu
- School of Mathematics and Statistics, Wuhan University, Wuhan 430072, Hubei, China.
| | - Jiangguo Liu
- Department of Mathematics, Colorado State University, Fort Collins, CO 80523-1874, USA.
| | - Simon Tavener
- Department of Mathematics, Colorado State University, Fort Collins, CO 80523-1874, USA.
| | - Xiufen Zou
- School of Mathematics and Statistics, Wuhan University, Wuhan 430072, Hubei, China.
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44
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Qiao X, Jeon J, Weber J, Zhu F, Chen B. Mechanism of polymorphism and curvature of HIV capsid assemblies probed by 3D simulations with a novel coarse grain model. Biochim Biophys Acta Gen Subj 2015; 1850:2353-67. [PMID: 26318016 DOI: 10.1016/j.bbagen.2015.08.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 08/17/2015] [Accepted: 08/19/2015] [Indexed: 12/11/2022]
Abstract
BACKGROUND During the maturation process, HIV capsid proteins self-assemble into polymorphic capsids. The strong polymorphism precludes high resolution structural characterization under in vivo conditions. In spite of the determination of structural models for various in vitro assemblies of HIV capsid proteins, the assembly mechanism is still not well-understood. METHODS We report 3D simulations of HIV capsid proteins by a novel coarse grain model that captures the backbone of the rigid segments in the protein accurately. The effects of protein dynamics on assembly are emulated by a static ensemble of subunits in conformations derived from molecular dynamics simulation. RESULTS We show that HIV capsid proteins robustly assemble into hexameric lattices in a range of conditions where trimers of dimeric subunits are the dominant oligomeric intermediates. Variations of hexameric lattice curvatures are observed in simulations with subunits of variable inter-domain orientations mimicking the conformation distribution in solution. Simulations with subunits based on pentameric structural models lead to assembly of sharp curved structures resembling the tips of authentic HIV capsids, along a distinct pathway populated by tetramers and pentamers with the characteristic quasi-equivalency of viral capsids. CONCLUSIONS Our results suggest that the polymorphism assembly is triggered by the inter-domain dynamics of HIV capsid proteins in solution. The assembly of highly curved structures arises from proteins in conformation with a highly specific inter-domain orientation. SIGNIFICANCE Our work proposes a mechanism of HIV capsid assembly based on available structural data, which can be readily verified. Our model can be applied to other large biomolecular assemblies.
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Affiliation(s)
- Xin Qiao
- Department of Physics, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816, USA
| | - Jaekyun Jeon
- Department of Physics, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816, USA
| | - Jeff Weber
- Department of Physics, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816, USA
| | - Fangqiang Zhu
- Department of Physics, Indiana University - Purdue University Indianapolis, IN, USA
| | - Bo Chen
- Department of Physics, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816, USA.
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45
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Affiliation(s)
- Fangqiang Zhu
- Department
of Physics, Indiana University - Purdue University, Indianapolis, Indiana 46202, United States
| | - Bo Chen
- Department
of Physics, University of Central Florida, Orlando, Florida 32816, United States
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46
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Molecular dynamics simulations of large macromolecular complexes. Curr Opin Struct Biol 2015; 31:64-74. [PMID: 25845770 DOI: 10.1016/j.sbi.2015.03.007] [Citation(s) in RCA: 264] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 03/13/2015] [Accepted: 03/16/2015] [Indexed: 12/11/2022]
Abstract
Connecting dynamics to structural data from diverse experimental sources, molecular dynamics simulations permit the exploration of biological phenomena in unparalleled detail. Advances in simulations are moving the atomic resolution descriptions of biological systems into the million-to-billion atom regime, in which numerous cell functions reside. In this opinion, we review the progress, driven by large-scale molecular dynamics simulations, in the study of viruses, ribosomes, bioenergetic systems, and other diverse applications. These examples highlight the utility of molecular dynamics simulations in the critical task of relating atomic detail to the function of supramolecular complexes, a task that cannot be achieved by smaller-scale simulations or existing experimental approaches alone.
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47
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Zhang L, Lua LHL, Middelberg APJ, Sun Y, Connors NK. Biomolecular engineering of virus-like particles aided by computational chemistry methods. Chem Soc Rev 2015; 44:8608-18. [DOI: 10.1039/c5cs00526d] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Multi-scale investigation of VLP self-assembly aided by computational methods is facilitating the design, redesign, and modification of functionalized VLPs.
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Affiliation(s)
- Lin Zhang
- Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of the Ministry of Education
- School of Chemical Engineering and Technology
- Tianjin University
- Tianjin 300072, People's Republic of China
| | - Linda H. L. Lua
- Protein Expression Facility
- The University of Queensland
- Brisbane, Australia
| | - Anton P. J. Middelberg
- Australian Institute for Bioengineering and Nanotechnology
- The University of Queensland
- Brisbane, Australia
| | - Yan Sun
- Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of the Ministry of Education
- School of Chemical Engineering and Technology
- Tianjin University
- Tianjin 300072, People's Republic of China
| | - Natalie K. Connors
- Australian Institute for Bioengineering and Nanotechnology
- The University of Queensland
- Brisbane, Australia
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48
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Abstract
Experimental evidence for in vivo capsid assembly suggests that capsid formation initiates from interactions between capsid (CA) proteins and lipids in the viral envelope. Various in vitro studies aiming to elucidate the detailed mechanisms of capsid self-assembly products have been carried out in conditions far removed from those, which would be encountered in a physiological environment. In this work we used lipid bilayers as a platform for studying the assembly of the CA protein with the rationale that the lipid-CA interactions play an important role in the nucleation of these structures. Observations using atomic force microscopy (AFM) have allowed a 'curling tadpole' mechanism to be suggested for the capsid self-assembly process. Stable dimeric CA proteins are able to move across the lipid bilayer to associate into trimers-of-dimers. These trimers form distinctly curved chains, which coil up to form larger features. As the feature grows additional trimers associate with the feature, giving a tadpole-like appearance. By comparing capsid assembly on mica, on single component lipid bilayers, and phase separated lipid bilayers, it was possible to determine the effect of lipid-protein interactions on capsid assembly.
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Affiliation(s)
- Penny Miles
- Chemical Engineering and Advanced Materials, Newcastle University, Newcastle Upon Tyne, NE1 7RU, UK.
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49
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Johnson GT, Goodsell DS, Autin L, Forli S, Sanner MF, Olson AJ. 3D molecular models of whole HIV-1 virions generated with cellPACK. Faraday Discuss 2014; 169:23-44. [PMID: 25253262 PMCID: PMC4569901 DOI: 10.1039/c4fd00017j] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 03/19/2014] [Indexed: 12/31/2022]
Abstract
As knowledge of individual biological processes grows, it becomes increasingly useful to frame new findings within their larger biological contexts in order to generate new systems-scale hypotheses. This report highlights two major iterations of a whole virus model of HIV-1, generated with the cellPACK software. cellPACK integrates structural and systems biology data with packing algorithms to assemble comprehensive 3D models of cell-scale structures in molecular detail. This report describes the biological data, modeling parameters and cellPACK methods used to specify and construct editable models for HIV-1. Anticipating that cellPACK interfaces under development will enable researchers from diverse backgrounds to critique and improve the biological models, we discuss how cellPACK can be used as a framework to unify different types of data across all scales of biology.
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50
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Smith GR, Xie L, Lee B, Schwartz R. Applying molecular crowding models to simulations of virus capsid assembly in vitro. Biophys J 2014; 106:310-20. [PMID: 24411263 DOI: 10.1016/j.bpj.2013.11.022] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Revised: 11/03/2013] [Accepted: 11/11/2013] [Indexed: 11/29/2022] Open
Abstract
Virus capsid assembly has been widely studied as a biophysical system, both for its biological and medical significance and as an important model for complex self-assembly processes. No current technology can monitor assembly in detail and what information we have on assembly kinetics comes exclusively from in vitro studies. There are many differences between the intracellular environment and that of an in vitro assembly assay, however, that might be expected to alter assembly pathways. Here, we explore one specific feature characteristic of the intracellular environment and known to have large effects on macromolecular assembly processes: molecular crowding. We combine prior particle simulation methods for estimating crowding effects with coarse-grained stochastic models of capsid assembly, using the crowding models to adjust kinetics of capsid simulations to examine possible effects of crowding on assembly pathways. Simulations suggest a striking difference depending on whether or not a system uses nucleation-limited assembly, with crowding tending to promote off-pathway growth in a nonnucleation-limited model but often enhancing assembly efficiency at high crowding levels even while impeding it at lower crowding levels in a nucleation-limited model. These models may help us understand how complicated assembly systems may have evolved to function with high efficiency and fidelity in the densely crowded environment of the cell.
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Affiliation(s)
- Gregory R Smith
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Lu Xie
- Joint Carnegie Mellon/University of Pittsburgh Ph.D. Program in Computational Biology, Carnegie Mellon University, Pittsburgh, Pennsylvania; Lane Center for Computational Biology, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Byoungkoo Lee
- Department of Mathematics and Statistics, Georgia State University, Atlanta, Georgia
| | - Russell Schwartz
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania; Lane Center for Computational Biology, Carnegie Mellon University, Pittsburgh, Pennsylvania.
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