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Choudhuri I, Biswas A, Haldane A, Levy RM. Contingency and Entrenchment of Drug-Resistance Mutations in HIV Viral Proteins. J Phys Chem B 2022; 126:10622-10636. [PMID: 36493468 PMCID: PMC9841799 DOI: 10.1021/acs.jpcb.2c06123] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The ability of HIV-1 to rapidly mutate leads to antiretroviral therapy (ART) failure among infected patients. Drug-resistance mutations (DRMs), which cause a fitness penalty to intrinsic viral fitness, are compensated by accessory mutations with favorable epistatic interactions which cause an evolutionary trapping effect, but the kinetics of this overall process has not been well characterized. Here, using a Potts Hamiltonian model describing epistasis combined with kinetic Monte Carlo simulations of evolutionary trajectories, we explore how epistasis modulates the evolutionary dynamics of HIV DRMs. We show how the occurrence of a drug-resistance mutation is contingent on favorable epistatic interactions with many other residues of the sequence background and that subsequent mutations entrench DRMs. We measure the time-autocorrelation of fluctuations in the likelihood of DRMs due to epistatic coupling with the sequence background, which reveals the presence of two evolutionary processes controlling DRM kinetics with two distinct time scales. Further analysis of waiting times for the evolutionary trapping effect to reverse reveals that the sequences which entrench (trap) a DRM are responsible for the slower time scale. We also quantify the overall strength of epistatic effects on the evolutionary kinetics for different mutations and show these are much larger for DRM positions than polymorphic positions, and we also show that trapping of a DRM is often caused by the collective effect of many accessory mutations, rather than a few strongly coupled ones, suggesting the importance of multiresidue sequence variations in HIV evolution. The analysis presented here provides a framework to explore the kinetic pathways through which viral proteins like HIV evolve under drug-selection pressure.
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Affiliation(s)
| | | | - Allan Haldane
- Center for Biophysics and Computational Biology, Temple University, Philadelphia, Pennsylvania 19122, United States; Department of Physics, Temple University, Philadelphia, Pennsylvania 19122-6008, United States
| | - Ronald M. Levy
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States; Center for Biophysics and Computational Biology, Temple University, Philadelphia, Pennsylvania 19122, United States
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2
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Sun Q, Biswas A, Vijayan RSK, Craveur P, Forli S, Olson AJ, Castaner AE, Kirby KA, Sarafianos SG, Deng N, Levy R. Structure-based virtual screening workflow to identify antivirals targeting HIV-1 capsid. J Comput Aided Mol Des 2022; 36:193-203. [PMID: 35262811 PMCID: PMC8904208 DOI: 10.1007/s10822-022-00446-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 02/24/2022] [Indexed: 02/07/2023]
Abstract
We have identified novel HIV-1 capsid inhibitors targeting the PF74 binding site. Acting as the building block of the HIV-1 capsid core, the HIV-1 capsid protein plays an important role in the viral life cycle and is an attractive target for antiviral development. A structure-based virtual screening workflow for hit identification was employed, which includes docking 1.6 million commercially-available drug-like compounds from the ZINC database to the capsid dimer, followed by applying two absolute binding free energy (ABFE) filters on the 500 top-ranked molecules from docking. The first employs the Binding Energy Distribution Analysis Method (BEDAM) in implicit solvent. The top-ranked compounds are then refined using the Double Decoupling method in explicit solvent. Both docking and BEDAM refinement were carried out on the IBM World Community Grid as part of the FightAIDS@Home project. Using this virtual screening workflow, we identified 24 molecules with calculated binding free energies between − 6 and − 12 kcal/mol. We performed thermal shift assays on these molecules to examine their potential effects on the stability of HIV-1 capsid hexamer and found that two compounds, ZINC520357473 and ZINC4119064 increased the melting point of the latter by 14.8 °C and 33 °C, respectively. These results support the conclusion that the two ZINC compounds are primary hits targeting the capsid dimer interface. Our simulations also suggest that the two hit molecules may bind at the capsid dimer interface by occupying a new sub-pocket that has not been exploited by existing CA inhibitors. The possible causes for why other top-scored compounds suggested by ABFE filters failed to show measurable activity are discussed.
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Affiliation(s)
- Qinfang Sun
- Center for Biophysics and Computational Biology and Department of Chemistry, Temple University, Philadelphia, PA, 19122, USA
| | - Avik Biswas
- Center for Biophysics and Computational Biology and Department of Chemistry, Temple University, Philadelphia, PA, 19122, USA
| | - R S K Vijayan
- Institute for Applied Cancer Science, MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Pierrick Craveur
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Stefano Forli
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Arthur J Olson
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Andres Emanuelli Castaner
- Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30322, USA.,Children's Healthcare of Atlanta, Atlanta, GA, 30322, USA
| | - Karen A Kirby
- Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30322, USA.,Children's Healthcare of Atlanta, Atlanta, GA, 30322, USA
| | - Stefan G Sarafianos
- Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30322, USA.,Children's Healthcare of Atlanta, Atlanta, GA, 30322, USA
| | - Nanjie Deng
- Department of Chemistry and Physical Sciences, Pace University, New York, NY, 10038, USA.
| | - Ronald Levy
- Center for Biophysics and Computational Biology and Department of Chemistry, Temple University, Philadelphia, PA, 19122, USA
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3
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Sadiq SK, Muñiz Chicharro A, Friedrich P, Wade RC. Multiscale Approach for Computing Gated Ligand Binding from Molecular Dynamics and Brownian Dynamics Simulations. J Chem Theory Comput 2021; 17:7912-7929. [PMID: 34739248 DOI: 10.1021/acs.jctc.1c00673] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We develop an approach to characterize the effects of gating by a multiconformation protein consisting of macrostate conformations that are either accessible or inaccessible to ligand binding. We first construct a Markov state model of the apo-protein from atomistic molecular dynamics simulations from which we identify macrostates and their conformations, compute their relative macrostate populations and interchange kinetics, and structurally characterize them in terms of ligand accessibility. We insert the calculated first-order rate constants for conformational transitions into a multistate gating theory from which we derive a gating factor γ that quantifies the degree of conformational gating. Applied to HIV-1 protease, our approach yields a kinetic network of three accessible (semi-open, open, and wide-open) and two inaccessible (closed and a newly identified, "parted") macrostate conformations. The parted conformation sterically partitions the active site, suggesting a possible role in product release. We find that the binding kinetics of drugs and drug-like inhibitors to HIV-1 protease falls in the slow gating regime. However, because γ = 0.75, conformational gating only modestly slows ligand binding. Brownian dynamics simulations of the diffusional association of eight inhibitors to the protease─having a wide range of experimental association constants (∼104-1010 M-1 s-1)─yields gated rate constants in the range of ∼0.5-5.7 × 108 M-1 s-1. This indicates that, whereas the association rate of some inhibitors could be described by the model, for many inhibitors either subsequent conformational transitions or alternate binding mechanisms may be rate-limiting. For systems known to be modulated by conformational gating, the approach could be scaled computationally efficiently to screen association kinetics for a large number of ligands.
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Affiliation(s)
- S Kashif Sadiq
- Molecular and Cellular Modeling Group, Heidelberg Institute for Theoretical Studies (HITS), Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany.,Genome Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany.,Infection Biology Unit, Universitat Pompeu Fabra, Barcelona Biomedical Research Park (PRBB), C/Doctor Aiguader 88, 08003 Barcelona, Spain
| | - Abraham Muñiz Chicharro
- Molecular and Cellular Modeling Group, Heidelberg Institute for Theoretical Studies (HITS), Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany.,Faculty of Biosciences, Heidelberg University, Im Neuenheimer Feld 234, 69120 Heidelberg, Germany
| | - Patrick Friedrich
- Molecular and Cellular Modeling Group, Heidelberg Institute for Theoretical Studies (HITS), Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany
| | - Rebecca C Wade
- Molecular and Cellular Modeling Group, Heidelberg Institute for Theoretical Studies (HITS), Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany.,Center for Molecular Biology (ZMBH), DKFZ-ZMBH Alliance, Heidelberg University, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany.,Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University, Im Neuenheimer Feld 205, 69120 Heidelberg, Germany
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4
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Classification and Design of HIV-1 Integrase Inhibitors Based on Machine Learning. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2021; 2021:5559338. [PMID: 33868450 PMCID: PMC8035010 DOI: 10.1155/2021/5559338] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 03/02/2021] [Accepted: 03/09/2021] [Indexed: 11/17/2022]
Abstract
A key enzyme in human immunodeficiency virus type 1 (HIV-1) life cycle, integrase (IN) aids the integration of viral DNA into the host DNA, which has become an ideal target for the development of anti-HIV drugs. A total of 1785 potential HIV-1 IN inhibitors were collected from the databases of ChEMBL, Binding Database, DrugBank, and PubMed, as well as from 40 references. The database was divided into the training set and test set by random sampling. By exploring the correlation between molecular descriptors and inhibitory activity, it is found that the classification and specific activity data of inhibitors can be more accurately predicted by the combination of molecular descriptors and molecular fingerprints. The calculation of molecular fingerprint descriptor provides the additional substructure information to improve the prediction ability. Based on the training set, two machine learning methods, the recursive partition (RP) and naive Bayes (NB) models, were used to build the classifiers of HIV-1 IN inhibitors. Through the test set verification, the RP technique accurately predicted 82.5% inhibitors and 86.3% noninhibitors. The NB model predicted 88.3% inhibitors and 87.2% noninhibitors with correlation coefficient of 85.2%. The results show that the prediction performance of NB model is slightly better than that of RP, and the key molecular segments are also obtained. Additionally, CoMFA and CoMSIA models with good activity prediction ability both were constructed by exploring the structure-activity relationship, which is helpful for the design and optimization of HIV-1 IN inhibitors.
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5
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Peng C, Wang J, Shi Y, Xu Z, Zhu W. Increasing the Sampling Efficiency of Protein Conformational Change by Combining a Modified Replica Exchange Molecular Dynamics and Normal Mode Analysis. J Chem Theory Comput 2020; 17:13-28. [PMID: 33351613 DOI: 10.1021/acs.jctc.0c00592] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Understanding conformational change at an atomic level is significant when determining a protein functional mechanism. Replica exchange molecular dynamics (REMD) is a widely used enhanced sampling method to explore protein conformational space. However, REMD with an explicit solvent model requires huge computational resources, immensely limiting its application. In this study, a variation of parallel tempering metadynamics (PTMetaD) with the omission of solvent-solvent interactions in exchange attempts and the use of low-frequency modes calculated by normal-mode analysis (NMA) as collective variables (CVs), namely ossPTMetaD, is proposed with the aim to accelerate MD simulations simultaneously in temperature and geometrical spaces. For testing the performance of ossPTMetaD, five protein systems with diverse biological functions and motion patterns were selected, including large-scale domain motion (AdK), flap movement (HIV-1 protease and BACE1), and DFG-motif flip in kinases (p38α and c-Abl). The simulation results showed that ossPTMetaD requires much fewer numbers of replicas than temperature REMD (T-REMD) with a reduction of ∼70% to achieve a similar exchange ratio. Although it does not obey the detailed balance condition, ossPTMetaD provides consistent results with T-REMD and experimental data. The high accessibility of the large conformational change of protein systems by ossPTMetaD, especially in simulating the very challenging DFG-motif flip of protein kinases, demonstrated its high efficiency and robustness in the characterization of the large-scale protein conformational change pathway and associated free energy profile.
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Affiliation(s)
- Cheng Peng
- CAS Key Laboratory of Receptor Research; Drug Discovery and Design Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China.,University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing, 100049, China
| | - Jinan Wang
- CAS Key Laboratory of Receptor Research; Drug Discovery and Design Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China
| | - Yulong Shi
- CAS Key Laboratory of Receptor Research; Drug Discovery and Design Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China.,University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing, 100049, China
| | - Zhijian Xu
- CAS Key Laboratory of Receptor Research; Drug Discovery and Design Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China.,University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing, 100049, China
| | - Weiliang Zhu
- CAS Key Laboratory of Receptor Research; Drug Discovery and Design Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China.,Open Studio for Druggability Research of Marine Lead Compounds, Qingdao National Laboratory for Marine Science and Technology, 1 Wenhai Road, Aoshanwei, Jimo, Qingdao 266237, China.,University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing, 100049, China
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6
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Dogan B, Durdagi S. Drug Re-positioning Studies for Novel HIV-1 Inhibitors Using Binary QSAR Models and Multi-target-driven In Silico Studies. Mol Inform 2020; 40:e2000012. [PMID: 33405326 DOI: 10.1002/minf.202000012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 08/16/2020] [Indexed: 12/20/2022]
Abstract
Current antiretroviral therapies against HIV involve the usage of at least two drugs that target different stages of HIV life cycle. However, potential drug interactions and side effects pose a problem. A promising concept for complex disease treatment is 'one molecule-multiple target' approach to overcome undesired effects of multiple drugs. Additionally, it is beneficial to consider drug re-purposing due to the cost of taking a drug into the market. Taking these into account, here potential anti-HIV compounds are suggested by virtually screening small approved drug molecules and clinical candidates. Initially, binary QSAR models are used to predict the therapeutic activity of around 7900 compounds against HIV and to predict the toxicity of molecules with high therapeutic activities. Selected compounds are considered for molecular docking studies against two targets, HIV-1 protease enzyme, and chemokine co-receptor CCR5. The top docking poses for all 549 molecules are then subjected to short (1 ns) individual molecular dynamics (MD) simulations and they are ranked based on their calculated relative binding free energies. Finally, 25 molecules are selected for long (200 ns) MD simulations, and 5 molecules are suggested as promising multi-target HIV agents. The results of this study may open new avenues for the designing of new dual HIV-1 inhibitor scaffolds.
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Affiliation(s)
- Berna Dogan
- Computational Biology and Molecular Simulations Laboratory, Department of Biophysics, School of Medicine, Bahcesehir University, Istanbul, Turkey
| | - Serdar Durdagi
- Computational Biology and Molecular Simulations Laboratory, Department of Biophysics, School of Medicine, Bahcesehir University, Istanbul, Turkey
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7
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Sakae Y, Zhang BW, Levy RM, Deng N. Absolute Protein Binding Free Energy Simulations for Ligands with Multiple Poses, a Thermodynamic Path That Avoids Exhaustive Enumeration of the Poses. J Comput Chem 2020; 41:56-68. [PMID: 31621932 PMCID: PMC7140983 DOI: 10.1002/jcc.26078] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 08/07/2019] [Accepted: 08/31/2019] [Indexed: 12/28/2022]
Abstract
We propose a free energy calculation method for receptor-ligand binding, which have multiple binding poses that avoids exhaustive enumeration of the poses. For systems with multiple binding poses, the standard procedure is to enumerate orientations of the binding poses, restrain the ligand to each orientation, and then, calculate the binding free energies for each binding pose. In this study, we modify a part of the thermodynamic cycle in order to sample a broader conformational space of the ligand in the binding site. This modification leads to more accurate free energy calculation without performing separate free energy simulations for each binding pose. We applied our modification to simple model host-guest systems as a test, which have only two binding poses, by using a single decoupling method (SDM) in implicit solvent. The results showed that the binding free energies obtained from our method without knowing the two binding poses were in good agreement with the benchmark results obtained by explicit enumeration of the binding poses. Our method is applicable to other alchemical binding free energy calculation methods such as the double decoupling method (DDM) in explicit solvent. We performed a calculation for a protein-ligand system with explicit solvent using our modified thermodynamic path. The results of the free energy simulation along our modified path were in good agreement with the results of conventional DDM, which requires a separate binding free energy calculation for each of the binding poses of the example of phenol binding to T4 lysozyme in explicit solvent. © 2019 Wiley Periodicals, Inc.
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Affiliation(s)
- Yoshitake Sakae
- Center for Biophysics and Computational Biology, Temple University, Philadelphia, Pennsylvania, 19122
| | - Bin W Zhang
- Center for Biophysics and Computational Biology, Temple University, Philadelphia, Pennsylvania, 19122
| | - Ronald M Levy
- Center for Biophysics and Computational Biology, Temple University, Philadelphia, Pennsylvania, 19122
- Department of Chemistry, Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania, 19122
| | - Nanjie Deng
- Department of Chemistry and Physical Sciences, Pace University, New York, New York, 10038
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8
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Bacci M, Caflisch A, Vitalis A. On the removal of initial state bias from simulation data. J Chem Phys 2019; 150:104105. [PMID: 30876362 DOI: 10.1063/1.5063556] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Classical atomistic simulations of biomolecules play an increasingly important role in molecular life science. The structure of current computing architectures favors methods that run multiple trajectories at once without requiring extensive communication between them. Many advanced sampling strategies in the field fit this mold. These approaches often rely on an adaptive logic and create ensembles of comparatively short trajectories whose starting points are not distributed according to the correct Boltzmann weights. This type of bias is notoriously difficult to remove, and Markov state models (MSMs) are one of the few strategies available for recovering the correct kinetics and thermodynamics from these ensembles of trajectories. In this contribution, we analyze the performance of MSMs in the thermodynamic reweighting task for a hierarchical set of systems. We show that MSMs can be rigorous tools to recover the correct equilibrium distribution for systems of sufficiently low dimensionality. This is conditional upon not tampering with local flux imbalances found in the data. For a real-world application, we find that a pure likelihood-based inference of the transition matrix produces the best results. The removal of the bias is incomplete, however, and for this system, all tested MSMs are outperformed by an alternative albeit less general approach rooted in the ideas of statistical resampling. We conclude by formulating some recommendations for how to address the reweighting issue in practice.
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Affiliation(s)
- Marco Bacci
- University of Zurich, Department of Biochemistry, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Amedeo Caflisch
- University of Zurich, Department of Biochemistry, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Andreas Vitalis
- University of Zurich, Department of Biochemistry, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
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9
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Conformational and dynamical basis for cross-reactivity observed between anti HIV-1 protease antibody with protease and an epitope peptide from it. Int J Biol Macromol 2018; 118:1696-1707. [PMID: 29990556 DOI: 10.1016/j.ijbiomac.2018.07.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Revised: 07/03/2018] [Accepted: 07/04/2018] [Indexed: 11/23/2022]
Abstract
F11.2.32 is a monoclonal antibody raised against HIV-1 protease and it inhibits protease activity. While the structure of the epitope peptide in complex with the antibody is known, how protease interacts with the antibody is not known. In this study, we model the conformational features of the free and bound epitope peptide and protease-antibody interactions. We find through our simulations, that the free epitope peptide P36-46 samples conformations akin to the bound conformation of the peptide in complex with the Ab, with a β-turn conformation sampled by the 38LPGR41 sequence highlighting the role of inherent conformational preferences of the peptide. Further, to determine the interactions present between the protease and antibody, we docked the protease in its conformation observed in the crystal structure, onto the antibody and simulated the dynamics of the complex in explicit water. We have identified the key residues involved in hydrogen-bond interactions and salt-bridges in Ag-Ab complex and examined the role of CDR flexibility in binding different conformations of the same epitope sequence in peptide and protein antigens. Thus, our results provide the basis for understanding the cross-reactivity observed between the antibody with protease and the epitope peptide from it.
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10
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Hadden JA, Perilla JR. All-atom virus simulations. Curr Opin Virol 2018; 31:82-91. [PMID: 30181049 DOI: 10.1016/j.coviro.2018.08.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 08/04/2018] [Accepted: 08/13/2018] [Indexed: 12/11/2022]
Abstract
The constant threat of viral disease can be combated by the development of novel vaccines and therapeutics designed to disrupt key features of virus structure or infection cycle processes. Such development relies on high-resolution characterization of viruses and their dynamical behaviors, which are often challenging to obtain solely by experiment. In response, all-atom molecular dynamics simulations are widely leveraged to study the structural components of viruses, leading to some of the largest simulation endeavors undertaken to date. The present work reviews exemplary all-atom simulation work on viruses, as well as progress toward simulating entire virions.
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Affiliation(s)
- Jodi A Hadden
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States.
| | - Juan R Perilla
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States
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11
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Király P, Kiss DJ, Tóth G. Committor of elementary reactions on multistate systems. J Chem Phys 2018; 148:134107. [PMID: 29626886 DOI: 10.1063/1.5007032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In our study, we extend the committor concept on multi-minima systems, where more than one reaction may proceed, but the feasible data evaluation needs the projection onto partial reactions. The elementary reaction committor and the corresponding probability density of the reactive trajectories are defined and calculated on a three-hole two-dimensional model system explored by single-particle Langevin dynamics. We propose a method to visualize more elementary reaction committor functions or probability densities of reactive trajectories on a single plot that helps to identify the most important reaction channels and the nonreactive domains simultaneously. We suggest a weighting for the energy-committor plots that correctly shows the limits of both the minimal energy path and the average energy concepts. The methods also performed well on the analysis of molecular dynamics trajectories of 2-chlorobutane, where an elementary reaction committor, the probability densities, the potential energy/committor, and the free-energy/committor curves are presented.
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Affiliation(s)
- Péter Király
- Institute of Chemistry, Eötvös Loránd University, Pázmány s. 1/a, H-1117 Budapest, Hungary
| | - Dóra Judit Kiss
- Institute of Chemistry, Eötvös Loránd University, Pázmány s. 1/a, H-1117 Budapest, Hungary
| | - Gergely Tóth
- Institute of Chemistry, Eötvös Loránd University, Pázmány s. 1/a, H-1117 Budapest, Hungary
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12
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Affiliation(s)
- Brooke E. Husic
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Vijay S. Pande
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
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13
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Cao Y, Jiang X, Han W. Self-Assembly Pathways of β-Sheet-Rich Amyloid-β(1-40) Dimers: Markov State Model Analysis on Millisecond Hybrid-Resolution Simulations. J Chem Theory Comput 2017; 13:5731-5744. [PMID: 29019683 DOI: 10.1021/acs.jctc.7b00803] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Early oligomerization during amyloid-β (Aβ) aggregation is essential for Aβ neurotoxicity. Understanding how unstructured Aβs assemble into oligomers, especially those rich in β-sheets, is essential but remains challenging as the assembly process is too transient for experimental characterization and too slow for molecular dynamics simulations. So far, atomic simulations are limited only to studies of either oligomer structures or assembly pathways for short Aβ segments. To overcome the computational challenge, we combine in this study a hybrid-resolution model and adaptive sampling techniques to perform over 2.7 ms of simulations of formation of full-length Aβ40 dimers that are the earliest toxic oligomeric species. The Markov state model is further employed to characterize the transition pathways and associated kinetics. Our results show that for two major forms of β-sheet-rich structures reported experimentally, the corresponding assembly mechanisms are markedly different. Hairpin-containing structures are formed by direct binding of soluble Aβ in β-hairpin-like conformations. Formation of parallel, in-register structures resembling fibrils occurs ∼100-fold more slowly and involves a rapid encounter of Aβ in arbitrary conformations followed by a slow structural conversion. The structural conversion proceeds via diverse pathways but always requires transient unfolding of encounter complexes. We find that the transition kinetics could be affected differently by intra-/intermolecular interactions involving individual residues in a conformation-dependent manner. In particular, the interactions involving Aβ's N-terminal part promote the assembly into hairpin-containing structures but delay the formation of fibril-like structures, thus explaining puzzling observations reported previously regarding the roles of this region in the early assembly process.
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Affiliation(s)
- Yang Cao
- Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School , Shenzhen, 518055, China
| | - Xuehan Jiang
- Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School , Shenzhen, 518055, China
| | - Wei Han
- Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School , Shenzhen, 518055, China
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14
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Zhang BW, Deng N, Tan Z, Levy RM. Stratified UWHAM and Its Stochastic Approximation for Multicanonical Simulations Which Are Far from Equilibrium. J Chem Theory Comput 2017; 13:4660-4674. [PMID: 28902500 PMCID: PMC5897113 DOI: 10.1021/acs.jctc.7b00651] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We describe a new analysis tool called Stratified unbinned Weighted Histogram Analysis Method (Stratified-UWHAM), which can be used to compute free energies and expectations from a multicanonical ensemble when a subset of the parallel simulations is far from being equilibrated because of barriers between free energy basins which are only rarely (or never) crossed at some states. The Stratified-UWHAM equations can be obtained in the form of UWHAM equations but with an expanded set of states. We also provide a stochastic solver, Stratified RE-SWHAM, for Stratified-UWHAM to remove its computational bottleneck. Stratified-UWHAM and Stratified RE-SWHAM are applied to study three test topics: the free energy landscape of alanine dipeptide, the binding affinity of a host-guest binding complex, and path sampling for a two-dimensional double well potential. The examples show that when some of the parallel simulations are only locally equilibrated, the estimates of free energies and equilibrium distributions provided by the conventional UWHAM (or MBAR) solutions exhibit considerable biases, but the estimates provided by Stratified-UWHAM and Stratified RE-SWHAM agree with the benchmark very well. Lastly, we discuss features of the Stratified-UWHAM approach which is based on coarse-graining in relation to two other maximum likelihood-based methods which were proposed recently, that also coarse-grain the multicanonical data.
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15
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Ronsard L, Ganguli N, Singh VK, Mohankumar K, Rai T, Sridharan S, Pajaniradje S, Kumar B, Rai D, Chaudhuri S, Coumar MS, Ramachandran VG, Banerjea AC. Impact of Genetic Variations in HIV-1 Tat on LTR-Mediated Transcription via TAR RNA Interaction. Front Microbiol 2017; 8:706. [PMID: 28484443 PMCID: PMC5399533 DOI: 10.3389/fmicb.2017.00706] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 04/05/2017] [Indexed: 01/10/2023] Open
Abstract
HIV-1 evades host defense through mutations and recombination events, generating numerous variants in an infected patient. These variants with an undiminished virulence can multiply rapidly in order to progress to AIDS. One of the targets to intervene in HIV-1 replication is the trans-activator of transcription (Tat), a major regulatory protein that transactivates the long terminal repeat promoter through its interaction with trans-activation response (TAR) RNA. In this study, HIV-1 infected patients (n = 120) from North India revealed Ser46Phe (20%) and Ser61Arg (2%) mutations in the Tat variants with a strong interaction toward TAR leading to enhanced transactivation activities. Molecular dynamics simulation data verified that the variants with this mutation had a higher binding affinity for TAR than both the wild-type Tat and other variants that lacked Ser46Phe and Ser61Arg. Other mutations in Tat conferred varying affinities for TAR interaction leading to differential transactivation abilities. This is the first report from North India with a clinical validation of CD4 counts to demonstrate the influence of Tat genetic variations affecting the stability of Tat and its interaction with TAR. This study highlights the co-evolution pattern of Tat and predominant nucleotides for Tat activity, facilitating the identification of genetic determinants for the attenuation of viral gene expression.
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Affiliation(s)
- Larance Ronsard
- Laboratory of Virology, National Institute of ImmunologyDelhi, India.,Department of Microbiology, University College of Medical Sciences and Guru Teg Bahadur HospitalDelhi, India
| | - Nilanjana Ganguli
- Laboratory of Virology, National Institute of ImmunologyDelhi, India
| | - Vivek K Singh
- Centre for Bioinformatics, School of Life Sciences, Pondicherry UniversityPondicherry, India
| | - Kumaravel Mohankumar
- Department of Biochemistry and Molecular Biology, Pondicherry UniversityPondicherry, India.,Department of Veterinary Physiology and Pharmacology, Texas A&M University, College StationTX, USA
| | - Tripti Rai
- Department of Gastroenterology and Human Nutrition, All India Institute of Medical SciencesDelhi, India
| | - Subhashree Sridharan
- Department of Biochemistry and Molecular Biology, Pondicherry UniversityPondicherry, India.,Department of Symptom Research, The University of Texas MD Anderson Cancer Center, HoustonTX, USA
| | - Sankar Pajaniradje
- Department of Biochemistry and Molecular Biology, Pondicherry UniversityPondicherry, India
| | - Binod Kumar
- Department of Microbiology and Immunology, Rosalind Franklin University of Medicine and Science, ChicagoIL, USA
| | - Devesh Rai
- Department of Microbiology, All India Institute of Medical SciencesDelhi, India
| | - Suhnrita Chaudhuri
- Department of Neurological Surgery, Northwestern University, ChicagoIL, USA
| | - Mohane S Coumar
- Centre for Bioinformatics, School of Life Sciences, Pondicherry UniversityPondicherry, India
| | | | - Akhil C Banerjea
- Laboratory of Virology, National Institute of ImmunologyDelhi, India
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16
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Huang YMM, Raymundo MAV, Chen W, Chang CEA. Mechanism of the Association Pathways for a Pair of Fast and Slow Binding Ligands of HIV-1 Protease. Biochemistry 2017; 56:1311-1323. [PMID: 28060481 DOI: 10.1021/acs.biochem.6b01112] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Equilibrium constants, together with kinetic rate constants of binding, are key factors in the efficacy and safety of drug compounds, informing drug design. However, the association pathways of protein-ligand binding, which contribute to their kinetic behaviors, are little understood. In this work, we used unbiased all-atom molecular dynamics (MD) simulations with an explicit solvent model to study the association processes of protein-ligand binding. Using the HIV protease (HIVp)-xk263 and HIVp-ritonavir protein-ligand systems as cases, we observed that ligand association is a multistep process involving diffusion, localization, and conformational rearrangements of the protein, ligand, and water molecules. Moreover, these two ligands preferred different routes of binding, which reflect two well-known binding mechanisms: induced-fit and conformation selection models. Our study shows that xk263 has a stronger capacity for desolvating surrounding water molecules, thereby inducing a semiopen conformation of the HIVp flaps (induced-fit model). In contrast, the slow dehydration characteristic of ritonavir allows for gradual association with the binding pocket of HIVp when the protein's flap conformation is fully open (conformation selection model). By studying the mechanism of ligand association and understanding the role of solvent molecules during the binding event, we can obtain a different perspective on the mechanism of macromolecule recognition, providing insights into drug discovery.
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Affiliation(s)
- Yu-Ming M Huang
- Department of Chemistry, University of California, Riverside , Riverside, California 92521, United States
| | - Mark Anthony V Raymundo
- Department of Chemistry, University of California, Riverside , Riverside, California 92521, United States
| | - Wei Chen
- Department of Chemistry, University of California, Riverside , Riverside, California 92521, United States.,ChemConsulting LLC , Frederick, Maryland 21704, United States
| | - Chia-En A Chang
- Department of Chemistry, University of California, Riverside , Riverside, California 92521, United States
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17
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Yu Y, Wang J, Chen Z, Wang G, Shao Q, Shi J, Zhu W. Structural insights into HIV-1 protease flap opening processes and key intermediates. RSC Adv 2017. [DOI: 10.1039/c7ra09691g] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The study provided an integrated view of the transition pathway of the flap opening of HIV-1 protease using MD simulation.
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Affiliation(s)
- Yuqi Yu
- Drug Discovery and Design Center
- CAS Key Laboratory of Receptor Research
- Shanghai Institute of Materia Medica
- Chinese Academy of Sciences
- Shanghai
| | - Jinan Wang
- Drug Discovery and Design Center
- CAS Key Laboratory of Receptor Research
- Shanghai Institute of Materia Medica
- Chinese Academy of Sciences
- Shanghai
| | - Zhaoqiang Chen
- Drug Discovery and Design Center
- CAS Key Laboratory of Receptor Research
- Shanghai Institute of Materia Medica
- Chinese Academy of Sciences
- Shanghai
| | - Guimin Wang
- Drug Discovery and Design Center
- CAS Key Laboratory of Receptor Research
- Shanghai Institute of Materia Medica
- Chinese Academy of Sciences
- Shanghai
| | - Qiang Shao
- Drug Discovery and Design Center
- CAS Key Laboratory of Receptor Research
- Shanghai Institute of Materia Medica
- Chinese Academy of Sciences
- Shanghai
| | - Jiye Shi
- UCB Biopharma SPRL
- Chemin du Foriest
- Belgium
| | - Weiliang Zhu
- Drug Discovery and Design Center
- CAS Key Laboratory of Receptor Research
- Shanghai Institute of Materia Medica
- Chinese Academy of Sciences
- Shanghai
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18
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Meng XM, Hu WJ, Mu YG, Sheng XH. Effect of allosteric molecules on structure and drug affinity of HIV-1 protease by molecular dynamics simulations. J Mol Graph Model 2016; 70:153-162. [PMID: 27723563 DOI: 10.1016/j.jmgm.2016.09.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2016] [Revised: 09/24/2016] [Accepted: 09/27/2016] [Indexed: 11/16/2022]
Abstract
Recent experiments show that small molecules can bind onto the allosteric sites of HIV-1 protease (PR), which provides a starting point for developing allosteric inhibitors. However, the knowledge of the effect of such binding on the structural dynamics and binding free energy of the active site inhibitor and PR is still lacking. Here, we report 200ns long molecular dynamics simulation results to gain insight into the influences of two allosteric molecules (1H-indole-6-carboxylic acid, 1F1 and 2-methylcyclohexano, 4D9). The simulations demonstrate that both allosteric molecules change the PR conformation and stabilize the structures of PR and the inhibitor; the residues of the flaps are sensitive to the allosteric molecules and the flexibility of the residues is pronouncedly suppressed; the additions of the small molecules to the allosteric sites strengthen the binding affinities of 3TL-PR by about 12-15kal/mol in the binding free energy, which mainly arises from electrostatic term. Interestingly, it is found that the action mechanisms of 1F1 and 4D9 are different, the former behaviors like a doorman that keeps the inhibitor from escape and makes the flaps (door) partially open; the latter is like a wedge that expands the allosteric space and meanwhile closes the flaps. Our data provide a theoretical support for designing the allosteric inhibitor.
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Affiliation(s)
- Xian-Mei Meng
- School of Physics and Electronics, Shandong Normal University, Jinan 250014, China
| | - Wei-Jun Hu
- School of Physics and Electronics, Shandong Normal University, Jinan 250014, China.
| | - Yu-Guang Mu
- School of Biological Sciences, Nanyang Technological University, Singapore 639815, Singapore.
| | - Xie-Huang Sheng
- School of Chemistry, Shandong Normal University, Jinan 250014, China
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19
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Li Y, Li X, Dong Z. Exploration of gated ligand binding recognizes an allosteric site for blocking FABP4-protein interaction. Phys Chem Chem Phys 2016; 17:32257-67. [PMID: 26580122 DOI: 10.1039/c5cp04784f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Fatty acid binding protein 4 (FABP4), reversibly binding to fatty acids and other lipids with high affinities, is a potential target for treatment of cancers. The binding site of FABP4 is buried in an interior cavity and thereby ligand binding/unbinding is coupled with opening/closing of FABP4. It is a difficult task both experimentally and computationally to illuminate the entry or exit pathway, especially with the conformational gating. In this report we combine extensive computer simulations, clustering analysis, and the Markov state model to investigate the binding mechanism of FABP4 and troglitazone. Our simulations capture spontaneous binding and unbinding events as well as the conformational transition of FABP4 between the open and closed states. An allosteric binding site on the protein surface is recognized for the development of novel FABP4 inhibitors. The binding affinity is calculated and compared with the experimental value. The kinetic analysis suggests that ligand residence on the protein surface may delay the binding process. Overall, our results provide a comprehensive picture of ligand diffusion on the protein surface, ligand migration into the buried cavity, and the conformational change of FABP4 at an atomic level.
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Affiliation(s)
- Yan Li
- The Hormel Institute, University of Minnesota, Austin Minnesota 55912, USA.
| | - Xiang Li
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Zhengzhou University, 450001 Zhengzhou, Henan, China
| | - Zigang Dong
- The Hormel Institute, University of Minnesota, Austin Minnesota 55912, USA.
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20
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Meng Y, Shukla D, Pande VS, Roux B. Transition path theory analysis of c-Src kinase activation. Proc Natl Acad Sci U S A 2016; 113:9193-8. [PMID: 27482115 PMCID: PMC4995974 DOI: 10.1073/pnas.1602790113] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Nonreceptor tyrosine kinases of the Src family are large multidomain allosteric proteins that are crucial to cellular signaling pathways. In a previous study, we generated a Markov state model (MSM) to simulate the activation of c-Src catalytic domain, used as a prototypical tyrosine kinase. The long-time kinetics of transition predicted by the MSM was in agreement with experimental observations. In the present study, we apply the framework of transition path theory (TPT) to the previously constructed MSM to characterize the main features of the activation pathway. The analysis indicates that the activating transition, in which the activation loop first opens up followed by an inward rotation of the αC-helix, takes place via a dense set of intermediate microstates distributed within a fairly broad "transition tube" in a multidimensional conformational subspace connecting the two end-point conformations. Multiple microstates with negligible equilibrium probabilities carry a large transition flux associated with the activating transition, which explains why extensive conformational sampling is necessary to accurately determine the kinetics of activation. Our results suggest that the combination of MSM with TPT provides an effective framework to represent conformational transitions in complex biomolecular systems.
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Affiliation(s)
- Yilin Meng
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637
| | - Diwakar Shukla
- Department of Chemistry, Stanford University, Stanford, CA 94305; Simulation of Biological Structures NIH Center for Biomedical Computation, Stanford University, Stanford, CA 94305
| | - Vijay S Pande
- Department of Chemistry, Stanford University, Stanford, CA 94305; Simulation of Biological Structures NIH Center for Biomedical Computation, Stanford University, Stanford, CA 94305
| | - Benoît Roux
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637;
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21
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Deng N, Zhang BW, Levy RM. Connecting free energy surfaces in implicit and explicit solvent: an efficient method to compute conformational and solvation free energies. J Chem Theory Comput 2016; 11:2868-78. [PMID: 26236174 DOI: 10.1021/acs.jctc.5b00264] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The ability to accurately model solvent effects on free energy surfaces is important for understanding many biophysical processes including protein folding and misfolding, allosteric transitions, and protein–ligand binding. Although all-atom simulations in explicit solvent can provide an accurate model for biomolecules in solution, explicit solvent simulations are hampered by the slow equilibration on rugged landscapes containing multiple basins separated by barriers. In many cases, implicit solvent models can be used to significantly speed up the conformational sampling; however, implicit solvent simulations do not fully capture the effects of a molecular solvent, and this can lead to loss of accuracy in the estimated free energies. Here we introduce a new approach to compute free energy changes in which the molecular details of explicit solvent simulations are retained while also taking advantage of the speed of the implicit solvent simulations. In this approach, the slow equilibration in explicit solvent, due to the long waiting times before barrier crossing, is avoided by using a thermodynamic cycle which connects the free energy basins in implicit solvent and explicit solvent using a localized decoupling scheme. We test this method by computing conformational free energy differences and solvation free energies of the model system alanine dipeptide in water. The free energy changes between basins in explicit solvent calculated using fully explicit solvent paths agree with the corresponding free energy differences obtained using the implicit/explicit thermodynamic cycle to within 0.3 kcal/mol out of ∼3 kcal/mol at only ∼8% of the computational cost. We note that WHAM methods can be used to further improve the efficiency and accuracy of the implicit/explicit thermodynamic cycle.
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Affiliation(s)
- Nanjie Deng
- Center for Biophysics & Computational Biology and Institute for Computational Molecular Sciences Temple University, Philadelphia, Pennsylvania 19122, United States
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22
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Investigation of Structural Dynamics of Enzymes and Protonation States of Substrates Using Computational Tools. Catalysts 2016; 6. [PMID: 27885336 PMCID: PMC5119520 DOI: 10.3390/catal6060082] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
This review discusses the use of molecular modeling tools, together with existing experimental findings, to provide a complete atomic-level description of enzyme dynamics and function. We focus on functionally relevant conformational dynamics of enzymes and the protonation states of substrates. The conformational fluctuations of enzymes usually play a crucial role in substrate recognition and catalysis. Protein dynamics can be altered by a tiny change in a molecular system such as different protonation states of various intermediates or by a significant perturbation such as a ligand association. Here we review recent advances in applying atomistic molecular dynamics (MD) simulations to investigate allosteric and network regulation of tryptophan synthase (TRPS) and protonation states of its intermediates and catalysis. In addition, we review studies using quantum mechanics/molecular mechanics (QM/MM) methods to investigate the protonation states of catalytic residues of β-Ketoacyl ACP synthase I (KasA). We also discuss modeling of large-scale protein motions for HIV-1 protease with coarse-grained Brownian dynamics (BD) simulations.
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23
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Abstract
It is now common knowledge that enzymes are mobile entities relying on complex atomic-scale dynamics and coordinated conformational events for proper ligand recognition and catalysis. However, the exact role of protein dynamics in enzyme function remains either poorly understood or difficult to interpret. This mini-review intends to reconcile biophysical observations and biological significance by first describing a number of common experimental and computational methodologies employed to characterize atomic-scale residue motions on various timescales in enzymes, and second by illustrating how the knowledge of these motions can be used to describe the functional behavior of enzymes and even act upon it. Two biologically relevant examples will be highlighted, namely the HIV-1 protease and DNA polymerase β enzyme systems.
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24
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Mahanti M, Bhakat S, Nilsson UJ, Söderhjelm P. Flap Dynamics in Aspartic Proteases: A Computational Perspective. Chem Biol Drug Des 2016; 88:159-77. [PMID: 26872937 DOI: 10.1111/cbdd.12745] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Recent advances in biochemistry and drug design have placed proteases as one of the critical target groups for developing novel small-molecule inhibitors. Among all proteases, aspartic proteases have gained significant attention due to their role in HIV/AIDS, malaria, Alzheimer's disease, etc. The binding cleft is covered by one or two β-hairpins (flaps) which need to be opened before a ligand can bind. After binding, the flaps close to retain the ligand in the active site. Development of computational tools has improved our understanding of flap dynamics and its role in ligand recognition. In the past decade, several computational approaches, for example molecular dynamics (MD) simulations, coarse-grained simulations, replica-exchange molecular dynamics (REMD) and metadynamics, have been used to understand flap dynamics and conformational motions associated with flap movements. This review is intended to summarize the computational progress towards understanding the flap dynamics of proteases and to be a reference for future studies in this field.
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Affiliation(s)
- Mukul Mahanti
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, PO Box 124, SE-221 00, Lund, Sweden
| | - Soumendranath Bhakat
- Division of Biophysical Chemistry, Department of Chemistry, Lund University, PO Box 124, SE-22100, Lund, Sweden
| | - Ulf J Nilsson
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, PO Box 124, SE-221 00, Lund, Sweden
| | - Pär Söderhjelm
- Division of Biophysical Chemistry, Department of Chemistry, Lund University, PO Box 124, SE-22100, Lund, Sweden
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25
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Cheng Z, Hoffmann A. A stochastic spatio-temporal (SST) model to study cell-to-cell variability in HIV-1 infection. J Theor Biol 2016; 395:87-96. [PMID: 26860658 DOI: 10.1016/j.jtbi.2016.02.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 02/01/2016] [Accepted: 02/01/2016] [Indexed: 10/22/2022]
Abstract
Although HIV viremia in infected patients proceeds in a manner that may be accounted for by deterministic mathematical models, single virus-cell encounters following initial HIV exposure result in a variety of outcomes, only one of which results in a productive infection. The development of single molecule tracking techniques in living cells allows studies of intracellular transport of HIV, but it remains less clear what its impact may be on viral integration efficiency. Here, we present a stochastic intracellular mathematical model of HIV replication that incorporates microtubule transport of viral components. Using this model, we could study single round infections and observe how viruses entering cells reach one of three potential fates - degradation of the viral RNA genome, formation of LTR circles, or successful integration and establishment of a provirus. Our model predicts global trafficking properties, such as the probability and the mean time for a HIV viral particle to reach the nuclear pore. Interestingly, our model predicts that trafficking determines neither the probability or time of provirus establishment - instead, they are a function of vRNA degradation and reverse transcription reactions. Thus, our spatio-temporal model provides novel insights into the HIV infection process and may constitute a useful tool for the identification of promising drug targets.
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Affiliation(s)
- Zhang Cheng
- Department of Microbiology, Immunology, and Molecular Genetics (MIMG), and Institute for Quantitative and Computational Biosciences (QCB), UC, Los Angeles, CA 92093, United States.
| | - Alexander Hoffmann
- Department of Microbiology, Immunology, and Molecular Genetics (MIMG), and Institute for Quantitative and Computational Biosciences (QCB), UC, Los Angeles, CA 92093, United States.
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26
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Nakashima M, Ode H, Suzuki K, Fujino M, Maejima M, Kimura Y, Masaoka T, Hattori J, Matsuda M, Hachiya A, Yokomaku Y, Suzuki A, Watanabe N, Sugiura W, Iwatani Y. Unique Flap Conformation in an HIV-1 Protease with High-Level Darunavir Resistance. Front Microbiol 2016; 7:61. [PMID: 26870021 PMCID: PMC4737996 DOI: 10.3389/fmicb.2016.00061] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 01/14/2016] [Indexed: 11/13/2022] Open
Abstract
Darunavir (DRV) is one of the most powerful protease inhibitors (PIs) for treating human immunodeficiency virus type-1 (HIV-1) infection and presents a high genetic barrier to the generation of resistant viruses. However, DRV-resistant HIV-1 infrequently emerges from viruses exhibiting resistance to other protease inhibitors. To address this resistance, researchers have gathered genetic information on DRV resistance. In contrast, few structural insights into the mechanism underlying DRV resistance are available. To elucidate this mechanism, we determined the crystal structure of the ligand-free state of a protease with high-level DRV resistance and six DRV resistance-associated mutations (including I47V and I50V), which we generated by in vitro selection. This crystal structure showed a unique curling conformation at the flap regions that was not found in the previously reported ligand-free protease structures. Molecular dynamics simulations indicated that the curled flap conformation altered the flap dynamics. These results suggest that the preference for a unique flap conformation influences DRV binding. These results provide new structural insights into elucidating the molecular mechanism of DRV resistance and aid to develop PIs effective against DRV-resistant viruses.
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Affiliation(s)
- Masaaki Nakashima
- Department of Infectious Diseases and Immunology, Clinical Research Center, National Hospital Organization Nagoya Medical CenterNagoya, Japan; Department of Biotechnology, Nagoya University Graduate School of EngineeringNagoya, Japan
| | - Hirotaka Ode
- Department of Infectious Diseases and Immunology, Clinical Research Center, National Hospital Organization Nagoya Medical Center Nagoya, Japan
| | - Koji Suzuki
- Department of Infectious Diseases and Immunology, Clinical Research Center, National Hospital Organization Nagoya Medical CenterNagoya, Japan; Department of Biotechnology, Nagoya University Graduate School of EngineeringNagoya, Japan
| | - Masayuki Fujino
- AIDS Research Center, National Institute of Infectious Diseases Tokyo, Japan
| | - Masami Maejima
- Department of Infectious Diseases and Immunology, Clinical Research Center, National Hospital Organization Nagoya Medical Center Nagoya, Japan
| | - Yuki Kimura
- Department of Infectious Diseases and Immunology, Clinical Research Center, National Hospital Organization Nagoya Medical CenterNagoya, Japan; Department of Biotechnology, Nagoya University Graduate School of EngineeringNagoya, Japan
| | - Takashi Masaoka
- Department of Infectious Diseases and Immunology, Clinical Research Center, National Hospital Organization Nagoya Medical Center Nagoya, Japan
| | - Junko Hattori
- Department of Infectious Diseases and Immunology, Clinical Research Center, National Hospital Organization Nagoya Medical Center Nagoya, Japan
| | - Masakazu Matsuda
- Department of Infectious Diseases and Immunology, Clinical Research Center, National Hospital Organization Nagoya Medical Center Nagoya, Japan
| | - Atsuko Hachiya
- Department of Infectious Diseases and Immunology, Clinical Research Center, National Hospital Organization Nagoya Medical Center Nagoya, Japan
| | - Yoshiyuki Yokomaku
- Department of Infectious Diseases and Immunology, Clinical Research Center, National Hospital Organization Nagoya Medical Center Nagoya, Japan
| | - Atsuo Suzuki
- Department of Biotechnology, Nagoya University Graduate School of Engineering Nagoya, Japan
| | - Nobuhisa Watanabe
- Department of Biotechnology, Nagoya University Graduate School of EngineeringNagoya, Japan; Synchrotron Radiation Research Center, Nagoya UniversityNagoya, Japan
| | - Wataru Sugiura
- Department of Infectious Diseases and Immunology, Clinical Research Center, National Hospital Organization Nagoya Medical Center Nagoya, Japan
| | - Yasumasa Iwatani
- Department of Infectious Diseases and Immunology, Clinical Research Center, National Hospital Organization Nagoya Medical CenterNagoya, Japan; Department of AIDS Research, Nagoya University Graduate School of MedicineNagoya, Japan
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27
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Shao Q. Enhanced conformational sampling technique provides an energy landscape view of large-scale protein conformational transitions. Phys Chem Chem Phys 2016; 18:29170-29182. [DOI: 10.1039/c6cp05634b] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
A novel in silico approach (NMA–ITS) is introduced to rapidly and effectively sample the configuration space and give quantitative data for exploring the conformational changes of proteins.
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Affiliation(s)
- Qiang Shao
- Drug Discovery and Design Center
- CAS Key Laboratory of Receptor Research
- Shanghai Institute of Materia Medica
- Chinese Academy of Sciences
- Shanghai
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28
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Nam GM, Makarov DE. Extracting intrinsic dynamic parameters of biomolecular folding from single-molecule force spectroscopy experiments. Protein Sci 2015; 25:123-34. [PMID: 26088347 DOI: 10.1002/pro.2727] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 06/17/2015] [Accepted: 06/17/2015] [Indexed: 11/12/2022]
Abstract
Single-molecule studies in which a mechanical force is transmitted to the molecule of interest and the molecular extension or position is monitored as a function of time are versatile tools for probing the dynamics of protein folding, stepping of molecular motors, and other biomolecular processes involving activated barrier crossing. One complication in interpreting such studies, however, is the fact that the typical size of a force probe (e.g., a dielectric bead in optical tweezers or the atomic force microscope tip/cantilever assembly) is much larger than the molecule itself, and so the observed molecular motion is affected by the hydrodynamic drag on the probe. This presents the experimenter with a nontrivial task of deconvolving the intrinsic molecular parameters, such as the intrinsic free energy barrier and the effective diffusion coefficient exhibited while crossing the barrier from the experimental signal. Here we focus on the dynamical aspect of this task and show how the intrinsic diffusion coefficient along the molecular reaction coordinate can be inferred from single-molecule measurements of the rates of biomolecular folding and unfolding. We show that the feasibility of accomplishing this task is strongly dependent on the relationship between the intrinsic molecular elasticity and that of the linker connecting the molecule to the force probe and identify the optimal range of instrumental parameters allowing determination of instrument-free molecular dynamics.
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Affiliation(s)
- Gi-Moon Nam
- Department of Chemistry, University of Texas at Austin, Austin, Texas, 78712
| | - Dmitrii E Makarov
- Department of Chemistry, University of Texas at Austin, Austin, Texas, 78712.,Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, Texas, 78712
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29
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Banerjee R, Yan H, Cukier RI. Conformational Transition in Signal Transduction: Metastable States and Transition Pathways in the Activation of a Signaling Protein. J Phys Chem B 2015; 119:6591-602. [DOI: 10.1021/acs.jpcb.5b02582] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Rahul Banerjee
- Department of Chemistry and ‡Department of
Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, United States
| | - Honggao Yan
- Department of Chemistry and ‡Department of
Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, United States
| | - Robert I. Cukier
- Department of Chemistry and ‡Department of
Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, United States
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30
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Huang YMM, Kang M, Chang CEA. Switches of hydrogen bonds during ligand-protein association processes determine binding kinetics. J Mol Recognit 2015; 27:537-48. [PMID: 25042708 DOI: 10.1002/jmr.2377] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 03/22/2014] [Accepted: 03/24/2014] [Indexed: 11/05/2022]
Abstract
Revealing the processes of ligand-protein associations deepens our understanding of molecular recognition and binding kinetics. Hydrogen bonds (H-bonds) play a crucial role in optimizing ligand-protein interactions and ligand specificity. In addition to the formation of stable H-bonds in the final bound state, the formation of transient H-bonds during binding processes contributes binding kinetics that define a ligand as a fast or slow binder, which also affects drug action. However, the effect of forming the transient H-bonds on the kinetic properties is little understood. Guided by results from coarse-grained Brownian dynamics simulations, we used classical molecular dynamics simulations in an implicit solvent model and accelerated molecular dynamics simulations in explicit waters to show that the position and distribution of the H-bond donor or acceptor of a drug result in switching intermolecular and intramolecular H-bond pairs during ligand recognition processes. We studied two major types of HIV-1 protease ligands: a fast binder, xk263, and a slow binder, ritonavir. The slow association rate in ritonavir can be attributed to increased flexibility of ritonavir, which yields multistep transitions and stepwise entering patterns and the formation and breaking of complex H-bond pairs during the binding process. This model suggests the importance of conversions of spatiotemporal H-bonds during the association of ligands and proteins, which helps in designing inhibitors with preferred binding kinetics.
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Affiliation(s)
- Yu-ming M Huang
- Department of Chemistry, University of California, Riverside, CA, 92521, USA
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31
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Molecular dynamics, monte carlo simulations, and langevin dynamics: a computational review. BIOMED RESEARCH INTERNATIONAL 2015; 2015:183918. [PMID: 25785262 PMCID: PMC4345249 DOI: 10.1155/2015/183918] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 11/05/2014] [Indexed: 01/08/2023]
Abstract
Macromolecular structures, such as neuraminidases, hemagglutinins, and monoclonal antibodies, are not rigid entities. Rather, they are characterised by their flexibility, which is the result of the interaction and collective motion of their constituent atoms. This conformational diversity has a significant impact on their physicochemical and biological properties. Among these are their structural stability, the transport of ions through the M2 channel, drug resistance, macromolecular docking, binding energy, and rational epitope design. To assess these properties and to calculate the associated thermodynamical observables, the conformational space must be efficiently sampled and the dynamic of the constituent atoms must be simulated. This paper presents algorithms and techniques that address the abovementioned issues. To this end, a computational review of molecular dynamics, Monte Carlo simulations, Langevin dynamics, and free energy calculation is presented. The exposition is made from first principles to promote a better understanding of the potentialities, limitations, applications, and interrelations of these computational methods.
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32
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Deng N, Forli S, He P, Perryman A, Wickstrom L, Vijayan RSK, Tiefenbrunn T, Stout D, Gallicchio E, Olson AJ, Levy RM. Distinguishing binders from false positives by free energy calculations: fragment screening against the flap site of HIV protease. J Phys Chem B 2014; 119:976-88. [PMID: 25189630 PMCID: PMC4306491 DOI: 10.1021/jp506376z] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
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Molecular docking is a powerful tool
used in drug discovery and
structural biology for predicting the structures of ligand–receptor
complexes. However, the accuracy of docking calculations can be limited
by factors such as the neglect of protein reorganization in the scoring
function; as a result, ligand screening can produce a high rate of
false positive hits. Although absolute binding free energy methods
still have difficulty in accurately rank-ordering binders, we believe
that they can be fruitfully employed to distinguish binders from nonbinders
and reduce the false positive rate. Here we study a set of ligands
that dock favorably to a newly discovered, potentially allosteric
site on the flap of HIV-1 protease. Fragment binding to this site
stabilizes a closed form of protease, which could be exploited for
the design of allosteric inhibitors. Twenty-three top-ranked protein–ligand
complexes from AutoDock were subject to the free energy screening
using two methods, the recently developed binding energy analysis
method (BEDAM) and the standard double decoupling method (DDM). Free
energy calculations correctly identified most of the false positives
(≥83%) and recovered all the confirmed binders. The results
show a gap averaging ≥3.7 kcal/mol, separating the binders
and the false positives. We present a formula that decomposes the
binding free energy into contributions from the receptor conformational
macrostates, which provides insights into the roles of different binding
modes. Our binding free energy component analysis further suggests
that improving the treatment for the desolvation penalty associated
with the unfulfilled polar groups could reduce the rate of false positive
hits in docking. The current study demonstrates that the combination
of docking with free energy methods can be very useful for more accurate
ligand screening against valuable drug targets.
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Affiliation(s)
- Nanjie Deng
- Center for Biophysics & Computational Biology/ICMS, ‡Department of Chemistry, Temple University , Philadelphia, Pennsylvania19122, United States
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33
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Han W, Schulten K. Fibril elongation by Aβ(17-42): kinetic network analysis of hybrid-resolution molecular dynamics simulations. J Am Chem Soc 2014; 136:12450-60. [PMID: 25134066 PMCID: PMC4156860 DOI: 10.1021/ja507002p] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
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A critical step of β-amyloid
fibril formation is fibril elongation
in which amyloid-β monomers undergo structural transitions to
fibrillar structures upon their binding to fibril tips. The atomic
detail of the structural transitions remains poorly understood. Computational
characterization of the structural transitions is limited so far to
short Aβ segments (5–10 aa) owing to the long time scale
of Aβ fibril elongation. To overcome the computational time
scale limit, we combined a hybrid-resolution model with umbrella sampling
and replica exchange molecular dynamics and performed altogether ∼1.3
ms of molecular dynamics simulations of fibril elongation for Aβ17–42. Kinetic network analysis of biased simulations
resulted in a kinetic model that encompasses all Aβ segments
essential for fibril formation. The model not only reproduces key
properties of fibril elongation measured in experiments, including
Aβ binding affinity, activation enthalpy of Aβ structural
transitions and a large time scale gap (τlock/τdock = 103–104) between Aβ
binding and its structural transitions, but also reveals detailed
pathways involving structural transitions not seen before, namely,
fibril formation both in hydrophobic regions L17-A21 and G37-A42 preceding
fibril formation in hydrophilic region E22-A30. Moreover, the model
identifies as important kinetic intermediates strand–loop–strand
(SLS) structures of Aβ monomers, long suspected to be related
to fibril elongation. The kinetic model suggests further that fibril
elongation arises faster at the fibril tip with exposed L17-A21, rather
than at the other tip, explaining thereby unidirectional fibril growth
observed previously in experiments.
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Affiliation(s)
- Wei Han
- Beckman Institute, ‡Center for Biophysics and Computational Biology, and §Department of Physics, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
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34
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Ung PMU, Dunbar JB, Gestwicki JE, Carlson HA. An allosteric modulator of HIV-1 protease shows equipotent inhibition of wild-type and drug-resistant proteases. J Med Chem 2014; 57:6468-78. [PMID: 25062388 PMCID: PMC4136727 DOI: 10.1021/jm5008352] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
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NMR
and MD simulations have demonstrated that the flaps of HIV-1 protease
(HIV-1p) adopt a range of conformations that are coupled with its
enzymatic activity. Previously, a model was created for an allosteric
site located between the flap and the core of HIV-1p, called the Eye
site (Biopolymers2008, 89, 643−65218381626). Here, results from our first study were
combined with a ligand-based, lead-hopping method to identify a novel
compound (NIT). NIT inhibits HIV-1p, independent of the presence of
an active-site inhibitor such as pepstatin A. Assays showed that NIT
acts on an allosteric site other than the dimerization interface.
MD simulations of the ligand–protein complex show that NIT
stably binds in the Eye site and restricts the flaps. That bound state
of NIT is consistent with a crystal structure of similar fragments
bound in the Eye site (Chem.
Biol. Drug Des.2010, 75, 257−26820659109). Most importantly,
NIT is equally potent against wild-type and a multidrug-resistant
mutant of HIV-1p, which highlights the promise of allosteric inhibitors
circumventing existing clinical resistance.
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Affiliation(s)
- Peter M-U Ung
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan , 428 Church Street, Ann Arbor, Michigan 48109-1065, United States
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35
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Savol AJ, Chennubhotla CS. Quantifying the Sources of Kinetic Frustration in Folding Simulations of Small Proteins. J Chem Theory Comput 2014; 10:2964-2974. [PMID: 25136267 PMCID: PMC4132847 DOI: 10.1021/ct500361w] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Indexed: 11/28/2022]
Abstract
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Experiments
and atomistic simulations of polypeptides have revealed
structural intermediates that promote or inhibit conformational transitions
to the native state during folding. We invoke a concept of “kinetic
frustration” to quantify the prevalence and impact of these
behaviors on folding rates within a large set of atomistic simulation
data for 10 fast-folding proteins, where each protein’s conformational
space is represented as a Markov state model of conformational transitions.
Our graph theoretic approach addresses what conformational features
correlate with folding inhibition and therefore permits comparison
among features within a single protein network and also more generally
between proteins. Nonnative contacts and nonnative secondary structure
formation can thus be quantitatively implicated in inhibiting folding
for several of the tested peptides.
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Affiliation(s)
- Andrej J Savol
- Dept. of Computational and Systems Biology, School of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States ; Joint Carnegie Mellon University-University of Pittsburgh PhD Program in Computational Biology, Pittsburgh, Pennsylvania 15260, United States
| | - Chakra S Chennubhotla
- Dept. of Computational and Systems Biology, School of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
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Abstract
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The Crk adaptor proteins play a central
role as a molecular timer
for the formation of protein complexes including various growth and
differentiation factors. The loss of regulation of Crk results in
many kinds of cancers. A self-regulatory mechanism for Crk was recently
proposed, which involves domain–domain rearrangement. It is
initiated by a cis–trans isomerization of a specific proline
residue (Pro238 in chicken Crk II) and can be accelerated by Cyclophilin
A. To understand how the proline switch controls the autoinhibition
at the molecular level, we performed large-scale molecular dynamics
and metadynamics simulations in the context of short peptides and
multidomain constructs of chicken Crk II. We found that the equilibrium
and kinetic properties of the macrostates are regulated not only by
the local environments of specified prolines but also by the global
organization of multiple domains. We observe the two macrostates (cis
closed/autoinhibited and trans open/uninhibited) consistent with NMR
experiments and predict barriers. We also propose an intermediate
state, the trans closed state, which interestingly was reported to
be a prevalent state in human Crk II. The existence of this macrostate
suggests that the rate of switching off the autoinhibition by Cyp
A may be limited by the relaxation rate of this intermediate state.
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Affiliation(s)
- Junchao Xia
- Department of Chemistry and Chemical Biology, Rutgers, the State University of New Jersey , 610 Taylor Road, Piscataway, New Jersey 08854, United States
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37
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Activation pathway of Src kinase reveals intermediate states as targets for drug design. Nat Commun 2014; 5:3397. [PMID: 24584478 PMCID: PMC4465921 DOI: 10.1038/ncomms4397] [Citation(s) in RCA: 256] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Accepted: 02/06/2014] [Indexed: 12/18/2022] Open
Abstract
Unregulated activation of Src kinases leads to aberrant signaling, uncontrolled growth, and differentiation of cancerous cells. Reaching a complete mechanistic understanding of large scale conformational transformations underlying the activation of kinases could greatly help in the development of therapeutic drugs for the treatment of these pathologies. In principle, the nature of conformational transition could be modeled in silico via atomistic molecular dynamics simulations, although this is very challenging due to the long activation timescales. Here, we employ a computational paradigm that couples transition pathway techniques and Markov state model-based massively distributed simulations for mapping the conformational landscape of c-src tyrosine kinase. The computations provide the thermodynamics and kinetics of kinase activation for the first time, and help identify key structural intermediates. Furthermore, the presence of a novel allosteric site in an intermediate state of c-src that could be potentially utilized for drug design is predicted.
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38
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Virtual screening of integrase inhibitors by large scale binding free energy calculations: the SAMPL4 challenge. J Comput Aided Mol Des 2014; 28:475-90. [PMID: 24504704 DOI: 10.1007/s10822-014-9711-9] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2013] [Accepted: 01/16/2014] [Indexed: 10/25/2022]
Abstract
As part of the SAMPL4 blind challenge, filtered AutoDock Vina ligand docking predictions and large scale binding energy distribution analysis method binding free energy calculations have been applied to the virtual screening of a focused library of candidate binders to the LEDGF site of the HIV integrase protein. The computational protocol leveraged docking and high level atomistic models to improve enrichment. The enrichment factor of our blind predictions ranked best among all of the computational submissions, and second best overall. This work represents to our knowledge the first example of the application of an all-atom physics-based binding free energy model to large scale virtual screening. A total of 285 parallel Hamiltonian replica exchange molecular dynamics absolute protein-ligand binding free energy simulations were conducted starting from docked poses. The setup of the simulations was fully automated, calculations were distributed on multiple computing resources and were completed in a 6-weeks period. The accuracy of the docked poses and the inclusion of intramolecular strain and entropic losses in the binding free energy estimates were the major factors behind the success of the method. Lack of sufficient time and computing resources to investigate additional protonation states of the ligands was a major cause of mispredictions. The experiment demonstrated the applicability of binding free energy modeling to improve hit rates in challenging virtual screening of focused ligand libraries during lead optimization.
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39
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Deng NJ, Dai W, Levy RM. How kinetics within the unfolded state affects protein folding: an analysis based on markov state models and an ultra-long MD trajectory. J Phys Chem B 2013; 117:12787-99. [PMID: 23705683 DOI: 10.1021/jp401962k] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Understanding how kinetics in the unfolded state affects protein folding is a fundamentally important yet less well-understood issue. Here we employ three different models to analyze the unfolded landscape and folding kinetics of the miniprotein Trp-cage. The first is a 208 μs explicit solvent molecular dynamics (MD) simulation from D. E. Shaw Research containing tens of folding events. The second is a Markov state model (MSM-MD) constructed from the same ultralong MD simulation; MSM-MD can be used to generate thousands of folding events. The third is a Markov state model built from temperature replica exchange MD simulations in implicit solvent (MSM-REMD). All the models exhibit multiple folding pathways, and there is a good correspondence between the folding pathways from direct MD and those computed from the MSMs. The unfolded populations interconvert rapidly between extended and collapsed conformations on time scales ≤40 ns, compared with the folding time of ∼5 μs. The folding rates are independent of where the folding is initiated from within the unfolded ensemble. About 90% of the unfolded states are sampled within the first 40 μs of the ultralong MD trajectory, which on average explores ∼27% of the unfolded state ensemble between consecutive folding events. We clustered the folding pathways according to structural similarity into "tubes", and kinetically partitioned the unfolded state into populations that fold along different tubes. From our analysis of the simulations and a simple kinetic model, we find that, when the mixing within the unfolded state is comparable to or faster than folding, the folding waiting times for all the folding tubes are similar and the folding kinetics is essentially single exponential despite the presence of heterogeneous folding paths with nonuniform barriers. When the mixing is much slower than folding, different unfolded populations fold independently, leading to nonexponential kinetics. A kinetic partition of the Trp-cage unfolded state is constructed which reveals that different unfolded populations have almost the same probability to fold along any of the multiple folding paths. We are investigating whether the results for the kinetics in the unfolded state of the 20-residue Trp-cage is representative of larger single domain proteins.
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Affiliation(s)
- Nan-jie Deng
- BioMaPS Institute for Quantitative Biology and Department of Chemistry and Chemical Biology, Rutgers, the State University of New Jersey , Piscataway, New Jersey 08854, United States
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40
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Xia J, Deng NJ, Levy RM. NMR relaxation in proteins with fast internal motions and slow conformational exchange: model-free framework and Markov state simulations. J Phys Chem B 2013; 117:6625-34. [PMID: 23638941 DOI: 10.1021/jp400797y] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Calculating NMR relaxation effects for proteins with dynamics on multiple time scales generally requires very long trajectories based on conventional molecular dynamics simulations. In this report, we have built Markov state models from multiple MD trajectories and used the resulting MSM to capture the very fast internal motions of the protein within a free energy basin on a time scale up to hundreds of picoseconds and the more than 3 orders of magnitude slower conformational exchange between macrostates. To interpret the relaxation data, we derive new equations using the model-free framework which includes two slowly exchanging macrostates, each of which also exhibits fast local motions. Using simulations of HIV-1 protease as an example, we show how the populations of slowly exchanging conformational states as well as order parameters for the different states can be determined from the NMR relaxation data.
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Affiliation(s)
- Junchao Xia
- Department of Chemistry and Chemical Biology and BioMaPS Institute for Quantitative Biology, Rutgers, the State University of New Jersey, 610 Taylor Road, Piscataway, New Jersey 08854, USA
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41
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How conformational changes can affect catalysis, inhibition and drug resistance of enzymes with induced-fit binding mechanism such as the HIV-1 protease. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1834:867-73. [PMID: 23376188 DOI: 10.1016/j.bbapap.2013.01.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Revised: 01/21/2013] [Accepted: 01/24/2013] [Indexed: 11/21/2022]
Abstract
A central question is how the conformational changes of proteins affect their function and the inhibition of this function by drug molecules. Many enzymes change from an open to a closed conformation upon binding of substrate or inhibitor molecules. These conformational changes have been suggested to follow an induced-fit mechanism in which the molecules first bind in the open conformation in those cases where binding in the closed conformation appears to be sterically obstructed such as for the HIV-1 protease. In this article, we present a general model for the catalysis and inhibition of enzymes with induced-fit binding mechanism. We derive general expressions that specify how the overall catalytic rate of the enzymes depends on the rates for binding, for the conformational changes, and for the chemical reaction. Based on these expressions, we analyze the effect of mutations that mainly shift the conformational equilibrium on catalysis and inhibition. If the overall catalytic rate is limited by product unbinding, we find that mutations that destabilize the closed conformation relative to the open conformation increase the catalytic rate in the presence of inhibitors by a factor exp(ΔΔGC/RT) where ΔΔGC is the mutation-induced shift of the free-energy difference between the conformations. This increase in the catalytic rate due to changes in the conformational equilibrium is independent of the inhibitor molecule and, thus, may help to understand how non-active-site mutations can contribute to the multi-drug-resistance that has been observed for the HIV-1 protease. A comparison to experimental data for the non-active-site mutation L90M of the HIV-1 protease indicates that the mutation slightly destabilizes the closed conformation of the enzyme. This article is part of a Special Issue entitled: The emerging dynamic view of proteins: Protein plasticity in allostery, evolution and self-assembly.
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42
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Ramanathan A, Savol AJ, Agarwal PK, Chennubhotla CS. Event detection and sub-state discovery from biomolecular simulations using higher-order statistics: application to enzyme adenylate kinase. Proteins 2012; 80:2536-51. [PMID: 22733562 DOI: 10.1002/prot.24135] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Revised: 05/08/2012] [Accepted: 06/10/2012] [Indexed: 12/25/2022]
Abstract
Biomolecular simulations at millisecond and longer time-scales can provide vital insights into functional mechanisms. Because post-simulation analyses of such large trajectory datasets can be a limiting factor in obtaining biological insights, there is an emerging need to identify key dynamical events and relating these events to the biological function online, that is, as simulations are progressing. Recently, we have introduced a novel computational technique, quasi-anharmonic analysis (QAA) (Ramanathan et al., PLoS One 2011;6:e15827), for partitioning the conformational landscape into a hierarchy of functionally relevant sub-states. The unique capabilities of QAA are enabled by exploiting anharmonicity in the form of fourth-order statistics for characterizing atomic fluctuations. In this article, we extend QAA for analyzing long time-scale simulations online. In particular, we present HOST4MD--a higher-order statistical toolbox for molecular dynamics simulations, which (1) identifies key dynamical events as simulations are in progress, (2) explores potential sub-states, and (3) identifies conformational transitions that enable the protein to access those sub-states. We demonstrate HOST4MD on microsecond timescale simulations of the enzyme adenylate kinase in its apo state. HOST4MD identifies several conformational events in these simulations, revealing how the intrinsic coupling between the three subdomains (LID, CORE, and NMP) changes during the simulations. Further, it also identifies an inherent asymmetry in the opening/closing of the two binding sites. We anticipate that HOST4MD will provide a powerful and extensible framework for detecting biophysically relevant conformational coordinates from long time-scale simulations.
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Affiliation(s)
- Arvind Ramanathan
- Computational Biology Institute & Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA
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43
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Ode H, Nakashima M, Kitamura S, Sugiura W, Sato H. Molecular dynamics simulation in virus research. Front Microbiol 2012; 3:258. [PMID: 22833741 PMCID: PMC3400276 DOI: 10.3389/fmicb.2012.00258] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Accepted: 07/02/2012] [Indexed: 01/24/2023] Open
Abstract
Virus replication in the host proceeds by chains of interactions between viral and host proteins. The interactions are deeply influenced by host immune molecules and anti-viral compounds, as well as by mutations in viral proteins. To understand how these interactions proceed mechanically and how they are influenced by mutations, one needs to know the structures and dynamics of the proteins. Molecular dynamics (MD) simulation is a powerful computational method for delineating motions of proteins at an atomic-scale via theoretical and empirical principles in physical chemistry. Recent advances in the hardware and software for biomolecular simulation have rapidly improved the precision and performance of this technique. Consequently, MD simulation is quickly extending the range of applications in biology, helping to reveal unique features of protein structures that would be hard to obtain by experimental methods alone. In this review, we summarize the recent advances in MD simulations in the study of virus–host interactions and evolution, and present future perspectives on this technique.
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Affiliation(s)
- Hirotaka Ode
- Clinical Research Center, National Hospital Organization Nagoya Medical Center Nagoya, Aichi, Japan
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44
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Long D, Brüschweiler R. Structural and Entropic Allosteric Signal Transduction Strength via Correlated Motions. J Phys Chem Lett 2012; 3:1722-1726. [PMID: 26285736 DOI: 10.1021/jz300488e] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Allosteric signal transduction in biomacromolecules can play an essential role in their function. Internal motional correlations in proteins provide a possible communication mechanism, but the quantitative relationship between statistical correlations and allostery is unknown. Quantitative relationships between internal motional correlations and the efficiency of propagation of allosteric structural and entropic effects are introduced and validated against conformational ensembles obtained from molecular dynamics simulations. This framework can explain a range of phenomena, such as the occurrence of an allosteric entropy change in the absence of any noticeable structural change.
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Affiliation(s)
- Dong Long
- Department of Chemistry and Biochemistry and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306, United States
| | - Rafael Brüschweiler
- Department of Chemistry and Biochemistry and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306, United States
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45
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In Silico Strategies Toward Enzyme Function and Dynamics. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2012. [DOI: 10.1016/b978-0-12-398312-1.00009-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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46
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BURGER VIRGINIAM, RAMANATHAN ARVIND, SAVOL ANDREJJ, STANLEY CHRISTOPHERB, AGARWAL PRATULK, CHENNUBHOTLA CHAKRAS. Quasi-anharmonic analysis reveals intermediate states in the nuclear co-activator receptor binding domain ensemble. PACIFIC SYMPOSIUM ON BIOCOMPUTING. PACIFIC SYMPOSIUM ON BIOCOMPUTING 2012:70-81. [PMID: 22174264 PMCID: PMC6568261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The molten globule nuclear receptor co-activator binding domain (NCBD) of CREB binding protein (CBP) selectively recruits transcription co-activators (TCAs) during the formation of the transcription preinitiation complex. NCBD:TCA interactions have been implicated in several cancers, however, the mechanisms of NCBD:TCA recognition remain uncharacterized. NCBD:TCA intermolecular recognition has challenged traditional investigation as both NCBD and several of its corresponding TCAs are intrinsically disordered. Using 40μs of explicit solvent molecular dynamics simulations, we relate the conformational diversity of ligand-free NCBD to its bound configurations. We introduce two novel techniques to quantify the conformational heterogeneity of ligand-free NCBD, dihedral quasi-anharmonic analysis (dQAA) and hierarchical graph-based diffusive clustering. With this integrated approach we find that three of four ligand-bound states are natively accessible to the ligand-free NCBD simulations with root-mean squared deviation (RMSD) less than 2Å These conformations are accessible via diverse pathways while a rate-limiting barrier must be crossed in order to access the fourth bound state.
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Affiliation(s)
- VIRGINIA M. BURGER
- Joint Carnegie Mellon University-University of Pittsburgh Ph.D. Program in Computational Biology, Oak Ridge, Tennessee 37831, USA
- Department of Computational and Systems Biology, University of Pittsburgh, Pennsylvania 15260, USA
| | - ARVIND RAMANATHAN
- Computational Biology Institute and Computer Science and Mathematics Division, Oak Ridge, Tennessee 37831, USA
| | - ANDREJ J. SAVOL
- Joint Carnegie Mellon University-University of Pittsburgh Ph.D. Program in Computational Biology, Oak Ridge, Tennessee 37831, USA
- Department of Computational and Systems Biology, University of Pittsburgh, Pennsylvania 15260, USA
| | - CHRISTOPHER B. STANLEY
- Neutron Scattering Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - PRATUL K. AGARWAL
- Computational Biology Institute and Computer Science and Mathematics Division, Oak Ridge, Tennessee 37831, USA
| | - CHAKRA S. CHENNUBHOTLA
- Department of Computational and Systems Biology, University of Pittsburgh, Pennsylvania 15260, USA
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47
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Lapelosa M, Gallicchio E, Levy RM. Conformational Transitions and Convergence of Absolute Binding Free Energy Calculations. J Chem Theory Comput 2011; 8:47-60. [PMID: 22368530 DOI: 10.1021/ct200684b] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The Binding Energy Distribution Analysis Method (BEDAM) is employed to compute the standard binding free energies of a series of ligands to a FK506 binding protein (FKBP12) with implicit solvation. Binding free energy estimates are in reasonably good agreement with experimental affinities. The conformations of the complexes identified by the simulations are in good agreement with crystallographic data, which was not used to restrain ligand orientations. The BEDAM method is based on λ -hopping Hamiltonian parallel Replica Exchange (HREM) molecular dynamics conformational sampling, the OPLS-AA/AGBNP2 effective potential, and multi-state free energy estimators (MBAR). Achieving converged and accurate results depends on all of these elements of the calculation. Convergence of the binding free energy is tied to the level of convergence of binding energy distributions at critical intermediate states where bound and unbound states are at equilibrium, and where the rate of binding/unbinding conformational transitions is maximal. This finding mirrors similar observations in the context of order/disorder transitions as for example in protein folding. Insights concerning the physical mechanism of ligand binding and unbinding are obtained. Convergence for the largest FK506 ligand is achieved only after imposing strict conformational restraints, which however require accurate prior structural knowledge of the structure of the complex. The analytical AGBNP2 model is found to underestimate the magnitude of the hydrophobic driving force towards binding in these systems characterized by loosely packed protein-ligand binding interfaces. Rescoring of the binding energies using a numerical surface area model corrects this deficiency. This study illustrates the complex interplay between energy models, exploration of conformational space, and free energy estimators needed to obtain robust estimates from binding free energy calculations.
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Affiliation(s)
- Mauro Lapelosa
- BioMaPS Institute for Quantitative Biology and Department of Chemistry and Chemical Biology, Rutgers the State University of New Jersey, Piscataway, NJ 08854
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48
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Long D, Brüschweiler R. Atomistic Kinetic Model for Population Shift and Allostery in Biomolecules. J Am Chem Soc 2011; 133:18999-9005. [DOI: 10.1021/ja208813t] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Dong Long
- Department of Chemistry and Biochemistry and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306, United States
| | - Rafael Brüschweiler
- Department of Chemistry and Biochemistry and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306, United States
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49
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Deng NJ, Zhang P, Cieplak P, Lai L. Elucidating the energetics of entropically driven protein-ligand association: calculations of absolute binding free energy and entropy. J Phys Chem B 2011; 115:11902-10. [PMID: 21899337 DOI: 10.1021/jp204047b] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The binding of proteins and ligands is generally associated with the loss of translational, rotational, and conformational entropy. In many cases, however, the net entropy change due to binding is positive. To develop a deeper understanding of the energetics of entropically driven protein-ligand binding, we calculated the absolute binding free energies and binding entropies for two HIV-1 protease inhibitors Nelfinavir and Amprenavir using the double-decoupling method with molecular dynamics simulations in explicit solvent. For both ligands, the calculated absolute binding free energies are in general agreement with experiments. The statistical error in the computed ΔG(bind) due to convergence problem is estimated to be ≥2 kcal/mol. The decomposition of free energies indicates that, although the binding of Nelfinavir is driven by nonpolar interaction, Amprenavir binding benefits from both nonpolar and electrostatic interactions. The calculated absolute binding entropies show that (1) Nelfinavir binding is driven by large entropy change and (2) the entropy of Amprenavir binding is much less favorable compared with that of Nelfinavir. Both results are consistent with experiments. To obtain qualitative insights into the entropic effects, we decomposed the absolute binding entropy into different contributions based on the temperature dependence of free energies along different legs of the thermodynamic pathway. The results suggest that the favorable entropic contribution to binding is dominated by the ligand desolvation entropy. The entropy gain due to solvent release from binding site appears to be more than offset by the reduction of rotational and vibrational entropies upon binding.
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Affiliation(s)
- Nan-jie Deng
- BioMaPS Institute for Quantitative Biology and Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States.
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