151
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Artikis E, Brooks CL. Modeling pH-Dependent NMR Chemical Shift Perturbations in Peptides. Biophys J 2019; 117:258-268. [PMID: 31255294 DOI: 10.1016/j.bpj.2019.06.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 04/20/2019] [Accepted: 06/03/2019] [Indexed: 11/29/2022] Open
Abstract
Modeling the pH dependence of protein and peptide chemical shifts outside the range of physiological values (6.5-7) is key to understanding structure-function relationships of these systems. These capabilities are largely not available in current chemical shift prediction software. In this study, we utilize a combination of molecular dynamics and quantum mechanics to investigate the through-space and through-bond contributions of protonation-dependent chemical shift perturbations (CSPs) in model tripeptides. By altering the protonation state of the titratable group in the tripeptides, we observe a notable difference in the conformational ensembles and attendantly compute significant CSPs for all nuclei near the site of protonation. We thus demonstrate the ability to recapitulate experimental pH-dependent CSPs with good agreement (R = 0.85, 0.99, and 0.98 for 13C, 15N, and 1H, respectively). Broadly, we provide the groundwork for incorporating pH effects into empirical and semiempirical chemical shift predictors.
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Affiliation(s)
| | - Charles L Brooks
- Biophysics Program, University of Michigan, Ann Arbor, Michigan; Department of Chemistry, University of Michigan, Ann Arbor, Michigan.
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152
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Proctor EA, Mowrey DD, Dokholyan NV. β-Methylamino-L-alanine substitution of serine in SOD1 suggests a direct role in ALS etiology. PLoS Comput Biol 2019; 15:e1007225. [PMID: 31323035 PMCID: PMC6668853 DOI: 10.1371/journal.pcbi.1007225] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 07/31/2019] [Accepted: 06/27/2019] [Indexed: 12/12/2022] Open
Abstract
Exposure to the environmental toxin β-methylamino-L-alanine (BMAA) is linked to amyotrophic lateral sclerosis (ALS), but its disease-promoting mechanism remains unknown. We propose that incorporation of BMAA into the ALS-linked protein Cu,Zn superoxide dismutase (SOD1) upon translation promotes protein misfolding and aggregation, which has been linked to ALS onset and progression. Using molecular simulation and predictive energetic computation, we demonstrate that substituting any serine with BMAA in SOD1 results in structural destabilization and aberrant dynamics, promoting neurotoxic SOD1 aggregation. We propose that translational incorporation of BMAA into SOD1 is directly responsible for its toxicity in neurodegeneration, and BMAA modification of SOD1 may serve as a biomarker of ALS.
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Affiliation(s)
- Elizabeth A. Proctor
- Departments of Neurosurgery, Pharmacology, and Biomedical Engineering, The Pennsylvania State University, Hershey, Pennsylvania, United States of America
| | - David D. Mowrey
- Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Nikolay V. Dokholyan
- Departments of Pharmacology, Biochemistry & Molecular Biology, Chemistry, and Biomedical Engineering, The Pennsylvania State University, Hershey, Pennsylvania, United States of America
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153
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Olson MA, Legler PM, Zabetakis D, Turner KB, Anderson GP, Goldman ER. Sequence Tolerance of a Single-Domain Antibody with a High Thermal Stability: Comparison of Computational and Experimental Fitness Profiles. ACS OMEGA 2019; 4:10444-10454. [PMID: 31460140 PMCID: PMC6648363 DOI: 10.1021/acsomega.9b00730] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 05/09/2019] [Indexed: 06/10/2023]
Abstract
The sequence fitness of a llama single-domain antibody with an unusually high thermal stability is explored by a combined computational and experimental study. Starting with the X-ray crystallographic structure, RosettaBackrub simulations were applied to model sequence-structure tolerance profiles and identify key substitution sites. From the model calculations, an experimental site-directed mutagenesis was used to produce a panel of mutants, and their melting temperatures were determined by thermal denaturation. The results reveal a sequence fitness of an excess stability of approximately 12 °C, a value taken from a decrease in the melting temperature of an electrostatic charge-reversal substitution in the CRD3 without a deleterious effect on the binding affinity to the antigen. The tolerance for the disruption of antigen recognition without loss in the thermal stability was demonstrated by the introduction of a proline in place of a tyrosine in the CDR2, producing a mutant that eliminated binding. To further assist the sequence design and the selection of engineered single-domain antibodies, an assessment of different computational strategies is provided of their accuracy in the detection of substitution "hot spots" in the sequence tolerance landscape.
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Affiliation(s)
- Mark A. Olson
- Systems
and Structural Biology Division, USAMRIID, Frederick, Maryland 21702, United States
| | - Patricia M. Legler
- Center
for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, District of Columbia 20375, United States
| | - Daniel Zabetakis
- Center
for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, District of Columbia 20375, United States
| | - Kendrick B. Turner
- Center
for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, District of Columbia 20375, United States
| | - George P. Anderson
- Center
for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, District of Columbia 20375, United States
| | - Ellen R. Goldman
- Center
for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, District of Columbia 20375, United States
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154
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Heo L, Arbour CF, Feig M. Driven to near-experimental accuracy by refinement via molecular dynamics simulations. Proteins 2019; 87:1263-1275. [PMID: 31197841 DOI: 10.1002/prot.25759] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Revised: 06/01/2019] [Accepted: 06/07/2019] [Indexed: 12/17/2022]
Abstract
Protein model refinement has been an essential part of successful protein structure prediction. Molecular dynamics simulation-based refinement methods have shown consistent improvement of protein models. There had been progress in the extent of refinement for a few years since the idea of ensemble averaging of sampled conformations emerged. There was little progress in CASP12 because conformational sampling was not sufficiently diverse due to harmonic restraints. During CASP13, a new refinement method was tested that achieved significant improvements over CASP12. The new method intended to address previous bottlenecks in the refinement problem by introducing new features. Flat-bottom harmonic restraints replaced harmonic restraints, sampling was performed iteratively, and a new scoring function and selection criteria were used. The new protocol expanded conformational sampling at reduced computational costs. In addition to overall improvements, some models were refined significantly to near-experimental accuracy.
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Affiliation(s)
- Lim Heo
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan
| | - Collin F Arbour
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan
| | - Michael Feig
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan
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155
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Schott-Verdugo S, Müller L, Classen E, Gohlke H, Groth G. Structural Model of the ETR1 Ethylene Receptor Transmembrane Sensor Domain. Sci Rep 2019; 9:8869. [PMID: 31222090 PMCID: PMC6586836 DOI: 10.1038/s41598-019-45189-w] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 06/03/2019] [Indexed: 01/14/2023] Open
Abstract
The structure, mechanism of action and copper stoichiometry of the transmembrane sensor domain of the plant ethylene receptor ETR1 and homologs have remained elusive, hampering the understanding on how the perception of the plant hormone ethylene is transformed into a downstream signal. We generated the first structural model of the transmembrane sensor domain of ETR1 by integrating ab initio structure prediction and coevolutionary information. To refine and independently validate the model, we determined protein-related copper stoichiometries on purified receptor preparations and explored the helix arrangement by tryptophan scanning mutagenesis. All-atom molecular dynamics simulations of the dimeric model reveal how ethylene can bind proximal to the copper ions in the receptor, illustrating the initial stages of the ethylene perception process.
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Affiliation(s)
- Stephan Schott-Verdugo
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- Centro de Bioinformática y Simulación Molecular (CBSM), Facultad de Ingeniería, Universidad de Talca, Talca, Chile
| | - Lena Müller
- Institute of Biochemical Plant Physiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Elisa Classen
- Institute of Biochemical Plant Physiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- Institute of Hydraulic Engineering and Water Resources Management, RWTH Aachen University, Aachen, Germany
| | - Holger Gohlke
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.
- John von Neumann Institute for Computing (NIC), Jülich Supercomputing Centre (JSC) & Institute for Complex Systems - Structural Biochemistry (ICS 6), Forschungszentrum Jülich GmbH, Jülich, Germany.
- Bioeconomy Science Center, Forschungszentrum Jülich GmbH, Jülich, Germany.
| | - Georg Groth
- Institute of Biochemical Plant Physiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.
- Bioeconomy Science Center, Forschungszentrum Jülich GmbH, Jülich, Germany.
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156
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Wong ETC, Gsponer J. Predicting Protein-Protein Interfaces that Bind Intrinsically Disordered Protein Regions. J Mol Biol 2019; 431:3157-3178. [PMID: 31207240 DOI: 10.1016/j.jmb.2019.06.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 06/01/2019] [Accepted: 06/04/2019] [Indexed: 12/18/2022]
Abstract
A long-standing goal in biology is the complete annotation of function and structure on all protein-protein interactions, a large fraction of which is mediated by intrinsically disordered protein regions (IDRs). However, knowledge derived from experimental structures of such protein complexes is disproportionately small due, in part, to challenges in studying interactions of IDRs. Here, we introduce IDRBind, a computational method that by combining gradient boosted trees and conditional random field models predicts binding sites of IDRs with performance approaching state-of-the-art globular interface predictions, making it suitable for proteome-wide applications. Although designed and trained with a focus on molecular recognition features, which are long interaction-mediating-elements in IDRs, IDRBind also predicts the binding sites of short peptides more accurately than existing specialized predictors. Consistent with IDRBind's specificity, a comparison of protein interface categories uncovered uniform trends in multiple physicochemical properties, positioning molecular recognition feature interfaces between peptide and globular interfaces.
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Affiliation(s)
- Eric T C Wong
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada; Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - Jörg Gsponer
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada; Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada.
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157
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Muller MP, Jiang T, Sun C, Lihan M, Pant S, Mahinthichaichan P, Trifan A, Tajkhorshid E. Characterization of Lipid-Protein Interactions and Lipid-Mediated Modulation of Membrane Protein Function through Molecular Simulation. Chem Rev 2019; 119:6086-6161. [PMID: 30978005 PMCID: PMC6506392 DOI: 10.1021/acs.chemrev.8b00608] [Citation(s) in RCA: 153] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The cellular membrane constitutes one of the most fundamental compartments of a living cell, where key processes such as selective transport of material and exchange of information between the cell and its environment are mediated by proteins that are closely associated with the membrane. The heterogeneity of lipid composition of biological membranes and the effect of lipid molecules on the structure, dynamics, and function of membrane proteins are now widely recognized. Characterization of these functionally important lipid-protein interactions with experimental techniques is however still prohibitively challenging. Molecular dynamics (MD) simulations offer a powerful complementary approach with sufficient temporal and spatial resolutions to gain atomic-level structural information and energetics on lipid-protein interactions. In this review, we aim to provide a broad survey of MD simulations focusing on exploring lipid-protein interactions and characterizing lipid-modulated protein structure and dynamics that have been successful in providing novel insight into the mechanism of membrane protein function.
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Affiliation(s)
- Melanie P. Muller
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- College of Medicine
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Tao Jiang
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Chang Sun
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Muyun Lihan
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Shashank Pant
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Paween Mahinthichaichan
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Anda Trifan
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Emad Tajkhorshid
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- College of Medicine
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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158
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Shao Q, Zhu W. Ligand binding effects on the activation of the EGFR extracellular domain. Phys Chem Chem Phys 2019; 21:8141-8151. [PMID: 30933195 DOI: 10.1039/c8cp07496h] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The epidermal growth factor receptor (EGFR) is one of the most common target proteins in anti-cancer therapy. The binding of the EGF ligand to the EGFR extracellular domain (EGFR-ECD) promotes its inactive-to-active conformational transition (activation) but the relevant detailed mechanism remains elusive still. Here, the structural characterization and energetics of the EGFR-ECD conformational transition with and without the binding of the EGF are quantitatively explored using an innovative enhanced sampling MD simulation method. Intriguingly, the EGF offers hydrophobic interactions (e.g., EGF residues of Tyr44 and Leu47) and electrostatic interactions (e.g., the EGF residues of Glu5, Asp11, Asp17, and Arg41) to play a dominant role in dragging domain III to close the ligand binding domain gap. Subsequently, the correlation between domains III and II is enhanced through salt-bridges among Glu376, Arg403, and Arg405 from domain III and Glu293, Glu295, and Arg300 from domain II. Finally, the structural bending of domain II is regulated to facilitate the disengagement of domain II from domain IV. In this regard, the functional conformational transition of EGFR-ECD is a consequence of the cooperative motion of protein domains driven by the EGF ligand binding. The present study shows a detailed scenario of the EGF induced activation of EGFR-ECD and provides valuable information for drug discovery targeting the EGFR.
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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, 555 Zuchongzhi Road, Shanghai, 201203, China.
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159
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Robertson MJ, Qian Y, Robinson MC, Tirado-Rives J, Jorgensen WL. Development and Testing of the OPLS-AA/M Force Field for RNA. J Chem Theory Comput 2019; 15:2734-2742. [PMID: 30807148 PMCID: PMC6585454 DOI: 10.1021/acs.jctc.9b00054] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Significant improvements have been made to the OPLS-AA force field for modeling RNA. New torsional potentials were optimized based on density functional theory (DFT) scans at the ωB97X-D/6-311++G(d,p) level for potential energy surfaces of the backbone α and γ dihedral angles. In combination with previously reported improvements for the sugar puckering and glycosidic torsion terms, the new force field was validated through diverse molecular dynamics simulations for RNAs in aqueous solution. Results for dinucleotides and tetranucleotides revealed both accurate reproduction of 3 J couplings from NMR and the avoidance of several unphysical states observed with other force fields. Simulations of larger systems with noncanonical motifs showed significant structural improvements over the previous OPLS-AA parameters. The new force field, OPLS-AA/M, is expected to perform competitively with other recent RNA force fields and to be compatible with OPLS-AA models for proteins and small molecules.
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Affiliation(s)
- Michael J. Robertson
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Yue Qian
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Matthew C. Robinson
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Julian Tirado-Rives
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - William L. Jorgensen
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
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160
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Brocke SA, Degen A, MacKerell AD, Dutagaci B, Feig M. Prediction of Membrane Permeation of Drug Molecules by Combining an Implicit Membrane Model with Machine Learning. J Chem Inf Model 2019; 59:1147-1162. [PMID: 30540459 PMCID: PMC6433486 DOI: 10.1021/acs.jcim.8b00648] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Lipid membrane permeation of drug molecules was investigated with Heterogeneous Dielectric Generalized Born (HDGB)-based models using solubility-diffusion theory and machine learning. Free energy profiles were obtained for neutral molecules by the standard HDGB and Dynamic HDGB (DHDGB) to account for the membrane deformation upon insertion of drugs. We also obtained hybrid free energy profiles where the neutralization of charged molecules was taken into account upon membrane insertion. The evaluation of the predictions was done against experimental permeability coefficients from Parallel Artificial Membrane Permeability Assays (PAMPA), and effects of partial charge sets, CGenFF, AM1-BCC, and OPLS, on the performance of the predictions were discussed. (D)HDGB-based models improved the predictions over the two-state implicit membrane models, and partial charge sets seemed to have a strong impact on the predictions. Machine learning increased the accuracy of the predictions, although it could not outperform the physics-based approach in terms of correlations.
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Affiliation(s)
- Stephanie A. Brocke
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, USA
| | - Alexandra Degen
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, USA
| | - Alexander D. MacKerell
- Department of Pharmaceutical Sciences, University of Maryland, School of Pharmacy, Baltimore, Maryland 21201, USA
- University of Maryland Computer-Aided Drug Design Center, Baltimore, Maryland 21201, USA
| | - Bercem Dutagaci
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, USA
| | - Michael Feig
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, USA
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161
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Albertolle ME, Song HD, Wilkey CJ, Segrest JP, Guengerich FP. Glutamine-451 Confers Sensitivity to Oxidative Inhibition and Heme-Thiolate Sulfenylation of Cytochrome P450 4B1. Chem Res Toxicol 2019; 32:484-492. [PMID: 30701961 PMCID: PMC7279892 DOI: 10.1021/acs.chemrestox.8b00353] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Human cytochrome P450 (P450) family 4 enzymes are involved in the metabolism of fatty acids and the bioactivation of carcinogenic arylamines and toxic natural products, e.g., 4-ipomeanol. These and other drug-metabolizing P450s are redox sensitive, showing a loss of activity resulting from preincubation with H2O2 and recovery with mild reducing agents [Albertolle, M. W., et al. (2017) J. Biol. Chem. 292, 11230-11242]. The inhibition is due to sulfenylation of the heme-thiolate ligand, as determined by chemopreoteomics and spectroscopy. This phenomenon may have implications for chemical toxicity and observed disease-drug interactions, in which the decreased metabolism of P450 substrates occurs in patients with inflammatory diseases (e.g., influenza and autoimmunity). Human P450 1A2 was determined to be redox insensitive. To determine the mechanism underlying the differential redox sensitivity, molecular dynamics (MD) simulations were employed using the crystal structure of rabbit P450 4B1 (Protein Data Bank entry 5T6Q ). In simulating either the thiolate (Cys-S-) or the sulfenic acid (Cys-SOH) at the heme ligation site, MD revealed Gln-451 in either an "open" or "closed" conformation, respectively, between the cytosol and heme-thiolate cysteine. Mutation to either an isosteric leucine (Q451L) or glutamate (Q451E) abrogated the redox sensitivity, suggesting that this "open" conformation allows for reduction of the sulfenic acid and religation of the thiolate to the heme iron. In summary, MD simulations suggest that Gln-451 in P450 4B1 adopts conformations that may stabilize and protect the heme-thiolate sulfenic acid; mutating this residue destabilizes the interaction, producing a redox insensitive enzyme.
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Affiliation(s)
- Matthew E. Albertolle
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, United States
| | - Hyun D. Song
- Department of Medicine, Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232-6300, United States
| | - Clayton J. Wilkey
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, United States
| | - Jere P. Segrest
- Department of Medicine, Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232-6300, United States
| | - F. Peter Guengerich
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, United States
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162
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Lee YV, Choi SB, Wahab HA, Lim TS, Choong YS. Applications of Ensemble Docking in Potential Inhibitor Screening for Mycobacterium tuberculosis Isocitrate Lyase Using a Local Plant Database. J Chem Inf Model 2019; 59:2487-2495. [PMID: 30840452 DOI: 10.1021/acs.jcim.8b00963] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Isocitrate lyase (ICL) is a persistent factor for the survival of dormant stage Mycobacterium tuberculosis (MTB), thus a potential drug target for tuberculosis treatment. In this work, ensemble docking approach was used to screen for potential inhibitors of ICL. The ensemble conformations of ICL active site were obtained from molecular dynamics simulation on three dimer form systems, namely the apo ICL, ICL in complex with metabolites (glyoxylate and succinate), and ICL in complex with substrate (isocitrate). Together with the ensemble conformations and the X-ray crystal structures, 22 structures were used for the screening against Malaysian Natural Compound Database (NADI). The top 10 compounds for each ensemble conformation were selected. The number of compounds was then further narrowed down to 22 compounds that were within the Lipinski's Rule of Five for drug-likeliness and were also docked into more than one ensemble conformation. Theses 22 compounds were furthered evaluate using whole cell assay. Some compounds were not commercially available; therefore, plant crude extracts were used for the whole cell assay. Compared to itaconate (the known inhibitor of ICL), crude extracts from Manilkara zapota, Morinda citrifolia, Vitex negundo, and Momordica charantia showed some inhibition activity. The MIC/MBC value were 12.5/25, 12.5/25, 0.78/1.6, and 0.39/1.6 mg/mL, respectively. This work could serve as a preliminary study in order to narrow the scope for high throughput screening in the future.
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Affiliation(s)
- Yie-Vern Lee
- Institute for Research in Molecular Medicine (INFORMM) , Universiti Sains Malaysia , 11800 Minden , Penang , Malaysia
| | - Sy Bing Choi
- School of Data Science , Perdana University , 43400 Sri Kembangan , Selangor , Malaysia
| | - Habibah A Wahab
- Pharmaceutical Design and Simulation Laboratory, School of Pharmaceutical Sciences , Universiti Sains Malaysia , 11800 Minden , Penang , Malaysia
| | - Theam Soon Lim
- Institute for Research in Molecular Medicine (INFORMM) , Universiti Sains Malaysia , 11800 Minden , Penang , Malaysia.,Analytical Biochemistry Research Centre , Universiti Sains Malaysia , 11800 Minden , Penang , Malaysia
| | - Yee Siew Choong
- Institute for Research in Molecular Medicine (INFORMM) , Universiti Sains Malaysia , 11800 Minden , Penang , Malaysia
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163
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Duan H, Liu X, Zhuo W, Meng J, Gu J, Sun X, Zuo K, Luo Q, Luo Y, Tang D, Shi H, Cao S, Hu J. 3D-QSAR and molecular recognition of Klebsiella pneumoniae NDM-1 inhibitors. MOLECULAR SIMULATION 2019. [DOI: 10.1080/08927022.2019.1579327] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Huaichuan Duan
- College of Pharmacy and Biological Engineering, Sichuan Industrial Institute of Antibiotics, Key Laboratory of Medicinal and Edible Plants Resources Development of Sichuan Education Department, Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Chengdu University, Chengdu, People’s Republic of China
| | - Xinyu Liu
- Laboratory of tumor targeted and immune therapy, Clinical Research Center for Breast, State Key Laboratory of Biotherapy, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu, People’s Republic of China
| | - Wei Zhuo
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, People’s Republic of China
| | - Jian Meng
- Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu, People’s Republic of China
| | - Jinke Gu
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, People’s Republic of China
| | - Xin Sun
- College of Pharmacy and Biological Engineering, Sichuan Industrial Institute of Antibiotics, Key Laboratory of Medicinal and Edible Plants Resources Development of Sichuan Education Department, Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Chengdu University, Chengdu, People’s Republic of China
| | - Ke Zuo
- College of Pharmacy and Biological Engineering, Sichuan Industrial Institute of Antibiotics, Key Laboratory of Medicinal and Edible Plants Resources Development of Sichuan Education Department, Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Chengdu University, Chengdu, People’s Republic of China
| | - Qing Luo
- College of Pharmacy and Biological Engineering, Sichuan Industrial Institute of Antibiotics, Key Laboratory of Medicinal and Edible Plants Resources Development of Sichuan Education Department, Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Chengdu University, Chengdu, People’s Republic of China
| | - Yafei Luo
- International Academy of Targeted Therapeutics and Innovation, Chongqing University of Arts and Sciences, Chongqing, People’s Republic of China
| | - Dianyong Tang
- International Academy of Targeted Therapeutics and Innovation, Chongqing University of Arts and Sciences, Chongqing, People’s Republic of China
| | - Hubing Shi
- Laboratory of tumor targeted and immune therapy, Clinical Research Center for Breast, State Key Laboratory of Biotherapy, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu, People’s Republic of China
| | - Shenghua Cao
- Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu, People’s Republic of China
| | - Jianping Hu
- College of Pharmacy and Biological Engineering, Sichuan Industrial Institute of Antibiotics, Key Laboratory of Medicinal and Edible Plants Resources Development of Sichuan Education Department, Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Chengdu University, Chengdu, People’s Republic of China
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164
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Ozsvar J, Tarakanova A, Wang R, Buehler MJ, Weiss AS. Allysine modifications perturb tropoelastin structure and mobility on a local and global scale. Matrix Biol Plus 2019; 2:100002. [PMID: 33543005 PMCID: PMC7852328 DOI: 10.1016/j.mbplus.2019.03.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 03/10/2019] [Accepted: 03/10/2019] [Indexed: 11/20/2022] Open
Abstract
Elastin provides elastic tissues with resilience through stretch and recoil cycles, and is primarily made of its extensively cross-linked monomer, tropoelastin. Here, we leverage the recently published full atomistic model of tropoelastin to assess how allysine modifications, which are essential to cross-linking, contribute to the dynamics and structural changes that occur in tropoelastin in the context of elastin assembly. We used replica exchange molecular dynamics to generate structural ensembles of allysine containing tropoelastin. We conducted principal component analysis on these ensembles and found that the molecule departs from the canonical structural ensemble. Furthermore, we showed that, while the canonical scissors-twist movement was retained, new movements emerged that deviated from those of the wild type protein, providing evidence for the involvement of a variety of molecular motions in elastin assembly. Additionally, we highlighted secondary structural changes and linked these perturbations to the longevity of specific salt bridges. We propose a model where allysines in tropoelastin contribute to hierarchical elastin assembly through global and local perturbations to molecular structure and dynamics. converting lysine to allysine by lysyl oxidases is needed to generate crosslinks between tropoelastin molecules in order to make elastin structural changes in the intact tropoelastin molecule ensue where modified tropoelastin molecules structurally depart from the canonical ensemble new molecular motions deviate from those of unmodified tropoelastin persistence times of specific salt bridges contribute to these perturbations allysines in tropoelastin contribute to hierarchical elastin assembly through global and local perturbations to molecular structure and dynamics
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Key Words
- 5ALK, tropoelastin containing 5 allysine residues
- ALK353, tropoelastin containing allysine at residue 353
- ALK353, tropoelastin containing allysine at residue 507
- ALL, allysine aldol
- ANM, anisotropic network model
- Assembly
- ECM, extracellular matrix
- Elastin
- LNL, lysinonorleucine
- MD, molecular dynamics
- Molecular dynamics
- NMA, normal mode analysis
- PCA, principal component analysis
- REMD, replica exchange molecular dynamics
- RMSD, root mean square deviation
- Replica exchange molecular dynamics
- SASA, solvent accessible surface area
- WT, wild type tropoelastin
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Affiliation(s)
- Jazmin Ozsvar
- Charles Perkins Centre, the University of Sydney, 2006 Sydney, NSW, Australia.,School of Life and Environmental Sciences, The University of Sydney, 2006 Sydney, NSW, Australia.,Cell Therapy Manufacturing Cooperative Research Centre, Adelaide, 5000, SA, Australia
| | - Anna Tarakanova
- Laboratory for Atomistic and Molecular Mechanics (LAMM), Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Richard Wang
- Charles Perkins Centre, the University of Sydney, 2006 Sydney, NSW, Australia.,School of Life and Environmental Sciences, The University of Sydney, 2006 Sydney, NSW, Australia
| | - Markus J Buehler
- Laboratory for Atomistic and Molecular Mechanics (LAMM), Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Anthony S Weiss
- Charles Perkins Centre, the University of Sydney, 2006 Sydney, NSW, Australia.,School of Life and Environmental Sciences, The University of Sydney, 2006 Sydney, NSW, Australia.,Cell Therapy Manufacturing Cooperative Research Centre, Adelaide, 5000, SA, Australia.,Bosch Institute, The University of Sydney, 2006 Sydney, NSW, Australia.,Sydney Nano Institute, The University of Sydney, 2006 Sydney, NSW, Australia
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165
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Aytenfisu AH, Simon R, MacKerell AD. Impact of branching on the conformational heterogeneity of the lipopolysaccharide from Klebsiella pneumoniae: Implications for vaccine design. Carbohydr Res 2019; 475:39-47. [PMID: 30818097 DOI: 10.1016/j.carres.2019.02.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 02/09/2019] [Accepted: 02/13/2019] [Indexed: 02/08/2023]
Abstract
Resistance of Klebsiella pneumoniae (KP) to antibiotics has motivated the development of an efficacious KP human vaccine that would not be subject to antibiotic resistance. Klebsiella lipopolysaccharide (LPS) associated O polysaccharide (OPS) types have provoked broad interest as a vaccine antigen as there are only 4 that predominate worldwide (O1, O2a, O3, O5). Klebsiella O1 and O2 OPS are polygalactans that share a common D-Gal-I structure, for which a variant D-Gal-III was recently discovered. To understand the potential impact of this variability on antigenicity, a detailed molecular picture of the conformational differences associated with the addition of the D-Gal-III (1 → 4)-α-Galp branch is presented using enhanced-sampling molecular dynamics simulations. In D-Gal-I two major conformational states are observed while the presence of the 1 → 4 branch in D-Gal-III resulted in only a single dominant extended state. Stabilization of the more folded states in D-Gal-I is due to a O4-H⋯O2 hydrogen bond in the linear backbone that cannot occur in D-Gal-III as the O4 is in the Galp(1 → 4)Galp glycosidic linkage. The impact of branching in D-Gal-III also significantly decreases the accessibility of the monosaccharides in the linear backbone region of D-Gal-I, while the accessibility of the terminal D-Gal-II region of the OPS is not substantially altered. The present results suggest that a vaccine that targets both the D-Gal-I and D-Gal-III LPS can be developed by using D-Gal-III as the antigen combined with cross-reactivity experiments using the Gal-II polysaccharide to assure that this region of the LPS is the primary epitope of the antigen.
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Affiliation(s)
- Asaminew H Aytenfisu
- University of Maryland Computer-Aided Drug Design Center, Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD, 21201, United States
| | - Raphael Simon
- Center for Vaccine Development, Institute for Global Health, School of Medicine, University of Maryland, Baltimore, MD, 21201, United States
| | - Alexander D MacKerell
- University of Maryland Computer-Aided Drug Design Center, Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD, 21201, United States.
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166
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Ariza Márquez YV, Briceño I, Aristizábal F, Niño LF, Yosa Reyes J. Dynamic Effects of CYP2D6 Genetic Variants in a Set of Poor Metaboliser Patients with Infiltrating Ductal Cancer Under Treatment with Tamoxifen. Sci Rep 2019; 9:2521. [PMID: 30792473 PMCID: PMC6385267 DOI: 10.1038/s41598-018-38340-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 12/19/2018] [Indexed: 12/28/2022] Open
Abstract
Breast cancer is a group of multigenic diseases. It is the most common cancer diagnosed among women worldwide and is often treated with tamoxifen. Tamoxifen is catalysed by cytochrome P450 2D6 (CYP2D6), and inter-individual variations in the enzyme due to single nucleotide polymorphisms (SNPs) could alter enzyme activity. We evaluated SNPs in patients from Colombia in South America who were receiving tamoxifen treatment for breast cancer. Allelic diversity in the CYP2D6 gene was found in the studied population, with two patients displaying the poor-metaboliser phenotype. Molecular dynamics and trajectory analyses were performed for CYP2D6 from these two patients, comparing it with the common allelic form (CYP2D6*1). Although we found no significant structural change in the protein, its dynamics differ significantly from those of CYP2D6*1, the effect of such differential dynamics resulting in an inefficient enzyme with serious implications for tamoxifen-treated patients, increasing the risk of disease relapse and ineffective treatment.
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MESH Headings
- Adult
- Aged
- Aged, 80 and over
- Antineoplastic Agents, Hormonal/administration & dosage
- Antineoplastic Agents, Hormonal/metabolism
- Breast Neoplasms/drug therapy
- Breast Neoplasms/genetics
- Breast Neoplasms/metabolism
- Breast Neoplasms/pathology
- Carcinoma, Ductal/drug therapy
- Carcinoma, Ductal/genetics
- Carcinoma, Ductal/metabolism
- Carcinoma, Ductal/pathology
- Chemotherapy, Adjuvant
- Cytochrome P-450 CYP2D6/genetics
- Cytochrome P-450 CYP2D6/metabolism
- Female
- Genotype
- Humans
- Inactivation, Metabolic/genetics
- Middle Aged
- Pharmacogenomic Variants/genetics
- Phenotype
- Polymorphism, Single Nucleotide/genetics
- Tamoxifen/administration & dosage
- Tamoxifen/adverse effects
- Tamoxifen/metabolism
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Affiliation(s)
- Yeimy Viviana Ariza Márquez
- Universidad Nacional de Colombia, Instituto de Biotecnología IBUN, Departamento de Farmacia, Bogota, 111321, Colombia
| | - Ignacio Briceño
- Universidad de la Sabana, Facultad de Medicina, Bogota, 140013, Colombia
- Pontificia Universidad Javeriana, Facultad de Medicina, Instituto de Genética Humana IGH, Bogota, 110231, Colombia
| | - Fabio Aristizábal
- Universidad Nacional de Colombia, Instituto de Biotecnología IBUN, Departamento de Farmacia, Bogota, 111321, Colombia
| | - Luis Fernando Niño
- Universidad Nacional de Colombia, Facultad de Ingeniería, Departamento de Ingeniería de Sistemas e Industrial, Bogota, 111321, Colombia
| | - Juvenal Yosa Reyes
- Universidad Simón Bolivar, Facultad de Ciencias Básicas y Biomédicas, Laboratorio de Simulación Molecular y Bioinformática, Barranquilla, 080002, Colombia.
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167
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Paquet-Côté PA, Fillion M, Provencher MÈ, Otis F, Dionne J, Cardinal S, Collignon B, Bürck J, Lagüe P, Ulrich AS, Auger M, Voyer N. Crown ether modified peptide interactions with model membranes‡. Supramol Chem 2019. [DOI: 10.1080/10610278.2019.1574349] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
| | - Matthieu Fillion
- Département de chimie, PROTEO, CERMA and CQMF, Université Laval, Québec, Canada
| | | | - François Otis
- Département de chimie and PROTEO, Université Laval, Québec, Canada
| | - Justine Dionne
- Département de chimie, PROTEO, CERMA and CQMF, Université Laval, Québec, Canada
| | | | - Barbara Collignon
- Département de biochimie, de microbiologie et de bio-informatique and PROTEO, Université Laval, Québec, Canada
| | - Jochen Bürck
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Patrick Lagüe
- Département de biochimie, de microbiologie et de bio-informatique and PROTEO, Université Laval, Québec, Canada
| | - Anne S. Ulrich
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Michèle Auger
- Département de chimie, PROTEO, CERMA and CQMF, Université Laval, Québec, Canada
| | - Normand Voyer
- Département de chimie and PROTEO, Université Laval, Québec, Canada
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168
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Yasuda S, Hayashi T, Kajiwara Y, Murata T, Kinoshita M. Analyses based on statistical thermodynamics for large difference between thermophilic rhodopsin and xanthorhodopsin in terms of thermostability. J Chem Phys 2019; 150:055101. [DOI: 10.1063/1.5082217] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Satoshi Yasuda
- Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage, Chiba 263-8522, Japan
- Molecular Chirality Research Center, Chiba University, 1-33 Yayoi-cho, Inage, Chiba 263-8522, Japan
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Tomohiko Hayashi
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Yuta Kajiwara
- Graduate School of Energy Science, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Takeshi Murata
- Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage, Chiba 263-8522, Japan
- Molecular Chirality Research Center, Chiba University, 1-33 Yayoi-cho, Inage, Chiba 263-8522, Japan
| | - Masahiro Kinoshita
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
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169
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Agrawal P, Singh H, Srivastava HK, Singh S, Kishore G, Raghava GPS. Benchmarking of different molecular docking methods for protein-peptide docking. BMC Bioinformatics 2019; 19:426. [PMID: 30717654 PMCID: PMC7394329 DOI: 10.1186/s12859-018-2449-y] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 10/29/2018] [Indexed: 11/10/2022] Open
Abstract
Background Molecular docking studies on protein-peptide interactions are a challenging and time-consuming task because peptides are generally more flexible than proteins and tend to adopt numerous conformations. There are several benchmarking studies on protein-protein, protein-ligand and nucleic acid-ligand docking interactions. However, a series of docking methods is not rigorously validated for protein-peptide complexes in the literature. Considering the importance and wide application of peptide docking, we describe benchmarking of 6 docking methods on 133 protein-peptide complexes having peptide length between 9 to 15 residues. The performance of docking methods was evaluated using CAPRI parameters like FNAT, I-RMSD, L-RMSD. Result Firstly, we performed blind docking and evaluate the performance of the top docking pose of each method. It was observed that FRODOCK performed better than other methods with average L-RMSD of 12.46 Å. The performance of all methods improved significantly for their best docking pose and achieved highest average L-RMSD of 3.72 Å in case of FRODOCK. Similarly, we performed re-docking and evaluated the performance of the top and best docking pose of each method. We achieved the best performance in case of ZDOCK with average L-RMSD 8.60 Å and 2.88 Å for the top and best docking pose respectively. Methods were also evaluated on 40 protein-peptide complexes used in the previous benchmarking study, where peptide have length up to 5 residues. In case of best docking pose, we achieved the highest average L-RMSD of 4.45 Å and 2.09 Å for the blind docking using FRODOCK and re-docking using AutoDock Vina respectively. Conclusion The study shows that FRODOCK performed best in case of blind docking and ZDOCK in case of re-docking. There is a need to improve the ranking of docking pose generated by different methods, as the present ranking scheme is not satisfactory. To facilitate the scientific community for calculating CAPRI parameters between native and docked complexes, we developed a web-based service named PPDbench (http://webs.iiitd.edu.in/raghava/ppdbench/). Electronic supplementary material The online version of this article (10.1186/s12859-018-2449-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Piyush Agrawal
- Center for Computation Biology, Indraprastha Institute of Information Technology, Okhla Phase III, New Delhi, 110020, India.,CSIR-Institute of Microbial Technology, Sector 39A, Chandigarh, India
| | - Harinder Singh
- CSIR-Institute of Microbial Technology, Sector 39A, Chandigarh, India
| | | | - Sandeep Singh
- CSIR-Institute of Microbial Technology, Sector 39A, Chandigarh, India
| | - Gaurav Kishore
- CSIR-Institute of Microbial Technology, Sector 39A, Chandigarh, India
| | - Gajendra P S Raghava
- Center for Computation Biology, Indraprastha Institute of Information Technology, Okhla Phase III, New Delhi, 110020, India. .,CSIR-Institute of Microbial Technology, Sector 39A, Chandigarh, India.
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170
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Lin Y, Im H, Diem LT, Ham S. Characterizing the structural and thermodynamic properties of Aβ42 and Aβ40. Biochem Biophys Res Commun 2019; 510:442-448. [PMID: 30722990 DOI: 10.1016/j.bbrc.2019.01.124] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 01/28/2019] [Indexed: 01/20/2023]
Abstract
The self-assembly of amyloid-beta (Aβ) proteins in aqueous extracellular environments is implicated in Alzheimer's disease. Among several alloforms of Aβ proteins differing in sequence length, the 42- and 40-residue forms (Aβ42 and Aβ40) are the most abundant ones in the human body. Although the only difference is the additional I41A42 residues in the C-terminus, Aβ42 exhibits more aggregation tendency and stronger neurotoxicity than Aβ40. Here, we investigate the molecular factors that confer more aggregation potential to Aβ42 than to Aβ40 based on molecular dynamics simulations combined with solvation thermodynamic analyses. It is observed that the most salient structural feature of Aβ42 relative to Aβ40 is the more enhanced β-sheet forming tendency, in particular in the C-terminal region. While such a structural characteristic of Aβ42 will certainly serve to facilitate the formation of aggregate species rich in β-sheet structure, we also detect its interesting thermodynamic consequence. Indeed, we find from the decomposition analysis that the C-terminal region substantially increases the solvation free energy (i.e., overall "hydrophobicity") of Aβ42, which is caused by the dehydration of the backbone moieties showing the enhanced tendency of forming the β-structure. Together with the two additional hydrophobic residues (I41A42), this leads to the higher solvation free energy of Aβ42, implying the larger water-mediated attraction toward the self-assembly. Thus, our computational results provide structural and thermodynamic grounds on why Aβ42 has more aggregation propensity than Aβ40 in aqueous environments.
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Affiliation(s)
- Yuxi Lin
- Department of Chemistry, The Research Institute of Natural Sciences, Sookmyung Women's University, Cheongpa-ro-47-gil 100, Yongsan-ku, Seoul, 04310, South Korea
| | - Haeri Im
- Department of Chemistry, The Research Institute of Natural Sciences, Sookmyung Women's University, Cheongpa-ro-47-gil 100, Yongsan-ku, Seoul, 04310, South Korea
| | - Le Thi Diem
- Department of Chemistry, The Research Institute of Natural Sciences, Sookmyung Women's University, Cheongpa-ro-47-gil 100, Yongsan-ku, Seoul, 04310, South Korea
| | - Sihyun Ham
- Department of Chemistry, The Research Institute of Natural Sciences, Sookmyung Women's University, Cheongpa-ro-47-gil 100, Yongsan-ku, Seoul, 04310, South Korea.
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171
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Zhao Z, Xie L, Bourne PE. Structural Insights into Characterizing Binding Sites in Epidermal Growth Factor Receptor Kinase Mutants. J Chem Inf Model 2019; 59:453-462. [PMID: 30582689 DOI: 10.1021/acs.jcim.8b00458] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Over the last two decades epidermal growth factor receptor (EGFR) kinase has become an important target to treat nonsmall cell lung cancer (NSCLC). Currently, three generations of EGFR kinase-targeted small molecule drugs have been FDA approved. They nominally produce a response at the start of treatment and lead to a substantial survival benefit for patients. However, long-term treatment results in acquired drug resistance and further vulnerability to NSCLC. Therefore, novel EGFR kinase inhibitors that specially overcome acquired mutations are urgently needed. To this end, we carried out a comprehensive study of different EGFR kinase mutants using a structural systems pharmacology strategy. Our analysis shows that both wild-type and mutated structures exhibit multiple conformational states that have not been observed in solved crystal structures. We show that this conformational flexibility accommodates diverse types of ligands with multiple types of binding modes. These results provide insights for designing a new generation of EGFR kinase inhibitor that combats acquired drug-resistant mutations through a multiconformation-based drug design strategy.
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Affiliation(s)
- Zheng Zhao
- Department of Biomedical Engineering , University of Virginia , Charlottesville , Virginia 22904 , United States of America
| | - Lei Xie
- Department of Computer Science, Hunter College , The City University of New York , New York , New York 10065 , United States of America.,The Graduate Center , The City University of New York , New York , New York 10016 , United States of America
| | - Philip E Bourne
- Department of Biomedical Engineering , University of Virginia , Charlottesville , Virginia 22904 , United States of America.,Data Science Institute , University of Virginia , Charlottesville , Virginia 22904 , United States of America
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172
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Garton M, Corbi-Verge C, Hu Y, Nim S, Tarasova N, Sherborne B, Kim PM. Rapid and accurate structure-based therapeutic peptide design using GPU accelerated thermodynamic integration. Proteins 2019; 87:236-244. [PMID: 30520126 DOI: 10.1002/prot.25644] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 10/30/2018] [Accepted: 11/29/2018] [Indexed: 11/07/2022]
Abstract
Peptide-based therapeutics are an alternative to small molecule drugs as they offer superior specificity, lower toxicity, and easy synthesis. Here we present an approach that leverages the dramatic performance increase afforded by the recent arrival of GPU accelerated thermodynamic integration (TI). GPU TI facilitates very fast, highly accurate binding affinity optimization of peptides against therapeutic targets. We benchmarked TI predictions using published peptide binding optimization studies. Prediction of mutations involving charged side-chains was found to be less accurate than for non-charged, and use of a more complex 3-step TI protocol was found to boost accuracy in these cases. Using the 3-step protocol for non-charged side-chains either had no effect or was detrimental. We use the benchmarked pipeline to optimize a peptide binding to our recently discovered cancer target: EME1. TI calculations predict beneficial mutations using both canonical and non-canonical amino acids. We validate these predictions using fluorescence polarization and confirm that binding affinity is increased. We further demonstrate that this increase translates to a significant reduction in pancreatic cancer cell viability.
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Affiliation(s)
- Michael Garton
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Canada
| | - Carles Corbi-Verge
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Canada
| | - Yuan Hu
- Merck & Co., Inc., Kenilworth, New Jersey.,Alkermes Inc., Waltham, Massachusetts
| | - Satra Nim
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Canada
| | - Nadya Tarasova
- Cancer and Inflammation Program, Center for Cancer Research, National Cancer Institute-Frederick, Frederick, Maryland
| | | | - Philip M Kim
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Canada.,Department of Computer Science, University of Toronto, Toronto, Canada
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173
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Abstract
The folding simulations of three ββα-motifs and β-barrel structured proteins (NTL9, NuG2b, and CspA) were performed to determine the important roles of native and nonnative contacts in protein folding.
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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
| | - 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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174
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Kaur H, Sain N, Mohanty D, Salunke DM. Deciphering evolution of immune recognition in antibodies. BMC STRUCTURAL BIOLOGY 2018; 18:19. [PMID: 30563492 PMCID: PMC6299584 DOI: 10.1186/s12900-018-0096-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 11/14/2018] [Indexed: 11/29/2022]
Abstract
Background Antibody, the primary effector molecule of the immune system, evolves after initial encounter with the antigen from a precursor form to a mature one to effectively deal with the antigen. Antibodies of a lineage diverge through antigen-directed isolated pathways of maturation to exhibit distinct recognition potential. In the context of evolution in immune recognition, diversity of antigen cannot be ignored. While there are reports on antibody lineage, structural perspective with respect to diverse recognition potential in a lineage has never been studied. Hence, it is crucial to evaluate how maturation leads to topological tailoring within a lineage enabling them to interact with significantly distinct antigens. Results A data-driven approach was undertaken for the study. Global experimental mouse and human antibody-antigen complex structures from PDB were compiled into a coherent database of germline-linked antibodies bound with distinct antigens. Structural analysis of all lineages showed variations in CDRs of both H and L chains. Observations of conformational adaptation made from analysis of static structures were further evaluated by characterizing dynamics of interaction in two lineages, mouse VH1–84 and human VH5–51. Sequence and structure analysis of the lineages explained that somatic mutations altered the geometries of individual antibodies with common structural constraints in some CDRs. Additionally, conformational landscape obtained from molecular dynamics simulations revealed that incoming pathogen led to further conformational divergence in the paratope (as observed across datasets) even while maintaining similar overall backbone topology. MM-GB/SA analysis showed binding energies to be in physiological range. Results of the study are coherent with experimental observations. Conclusions The findings of this study highlight basic structural principles shaping the molecular evolution of a lineage for significantly diverse antigens. Antibodies of a lineage follow different developmental pathways while preserving the imprint of the germline. From the study, it can be generalized that structural diversification of the paratope is an outcome of natural selection of a conformation from an available ensemble, which is further optimized for antigen interaction. The study establishes that starting from a common lineage, antibodies can mature to recognize a wide range of antigens. This hypothesis can be further tested and validated experimentally. Electronic supplementary material The online version of this article (10.1186/s12900-018-0096-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Harmeet Kaur
- Regional Centre for Biotechnology, Biotech Science Cluster, Faridabad, Haryana, 121001, India.,Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - Neetu Sain
- National Institute of Immunology, New Delhi, Delhi, 110067, India
| | - Debasisa Mohanty
- National Institute of Immunology, New Delhi, Delhi, 110067, India
| | - Dinakar M Salunke
- Regional Centre for Biotechnology, Biotech Science Cluster, Faridabad, Haryana, 121001, India. .,International Centre for Genetic Engineering and Biotechnology, New Delhi, Delhi, 110067, India.
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175
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Pepino AJ, Segarra-Martí J, Nenov A, Rivalta I, Improta R, Garavelli M. UV-induced long-lived decays in solvated pyrimidine nucleosides resolved at the MS-CASPT2/MM level. Phys Chem Chem Phys 2018; 20:6877-6890. [PMID: 29459916 DOI: 10.1039/c7cp08235e] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The most relevant 'dark' electronic excited states in DNA/RNA pyrimidine nucleosides are mapped in water employing hybrid MS-CASPT2/MM optimisations with explicit solvation and including the sugar. Conical intersections (CIs) between initially accessed bright 1ππ* and the lowest energy dark 1nπ* excited states, involving the lone pair localised on the oxygen and/or nitrogen atoms are characterised. They are found in the vicinities of the Franck-Condon (FC) region and are shown to facilitate non-adiabatic population transfer. The excited state population of the 1nOπ* state, localised in the carbonyl moiety on all pyrimidine nucleosides, is predicted to rapidly evolve to its minimum, displaying non-negligible potential energy barriers along its non-radiative decay, and accounting for the ps signal registered in pump-probe experiments as well as for an efficient population of the triplet state. Cytidine displays an additional 1nNπ* state localised in the N3 atom and that leads to its excited state minimum displaying large potential energy barriers in the pathway connecting to the CI with the ground state. Sugar-to-base hydrogen/proton transfer processes are assessed in solution for the first time, displaying a sizable barrier along its decay and thus being competitive with other slow decay channels in the ps and ns timescales. A unified deactivation scheme for the long-lived channels of pyrimidine nucleosides is delivered, where the 1nOπ* state is found to mediate the long-lived decay in the singlet manifold and act as the doorway for triplet population and thus accounting for the recorded phosphorescence and, more generally, for the transient/photoelectron spectral signals registered up to the ns timescale.
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Affiliation(s)
- Ana Julieta Pepino
- Dipartimento di Chimica Industriale "Toso Montanari", Università di Bologna, Viale del Risorgimento 4, I-40136 Bologna, Italy.
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176
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Shao Q, Zhu W. Assessing AMBER force fields for protein folding in an implicit solvent. Phys Chem Chem Phys 2018; 20:7206-7216. [PMID: 29480910 DOI: 10.1039/c7cp08010g] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Molecular dynamics (MD) simulation implemented with a state-of-the-art protein force field and implicit solvent model is an attractive approach to investigate protein folding, one of the most perplexing problems in molecular biology. But how well can force fields developed independently of implicit solvent models work together in reproducing diverse protein native structures and measuring the corresponding folding thermodynamics is not always clear. In this work, we performed enhanced sampling MD simulations to assess the ability of six AMBER force fields (FF99SBildn, FF99SBnmr, FF12SB, FF14ipq, FF14SB, and FF14SBonlysc) as coupled with a recently improved pair-wise GB-Neck2 model in modeling the folding of two helical and two β-sheet peptides. Whilst most of the tested force fields can yield roughly similar features for equilibrium conformational ensembles and detailed folding free-energy profiles for short α-helical TC10b in an implicit solvent, the measured counterparts are significantly discrepant in the cases of larger or β-structured peptides (HP35, 1E0Q, and GTT). Additionally, the calculated folding/unfolding thermodynamic quantities can only partially match the experimental data. Although a combination of the force fields and GB-Neck2 implicit model able to describe all aspects of the folding transitions towards the native structures of all the considered peptides was not identified, we found that FF14SBonlysc coupled with the GB-Neck2 model seems to be a reasonably balanced combination to predict peptide folding preferences.
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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, 555 Zuchongzhi Road, Shanghai, 201203, China.
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177
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Yildirim A, Brenner N, Sutherland R, Feig M. Role of protein interactions in stabilizing canonical DNA features in simulations of DNA in crowded environments. BMC BIOPHYSICS 2018; 11:8. [PMID: 30555686 PMCID: PMC6286541 DOI: 10.1186/s13628-018-0048-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 11/21/2018] [Indexed: 11/28/2022]
Abstract
Background Cellular environments are highly crowded with biological macromolecules resulting in frequent non-specific interactions. While the effect of such crowding on protein structure and dynamics has been studied extensively, very little is known how cellular crowding affects the conformational sampling of nucleic acids. Results The effect of protein crowding on the conformational preferences of DNA (deoxyribonucleic acid) is described from fully atomistic molecular dynamics simulations of systems containing a DNA dodecamer surrounded by protein crowders. From the simulations, it was found that DNA structures prefer to stay in B-like conformations in the presence of the crowders. The preference for B-like conformations results from non-specific interactions of crowder proteins with the DNA sugar-phosphate backbone. Moreover, the simulations suggest that the crowder interactions narrow the conformational sampling to canonical regions of the conformational space. Conclusions The overall conclusion is that crowding effects may stabilize the canonical features of DNA that are most important for biological function. The results are complementary to a previous study of DNA in reduced dielectric environments where reduced dielectric environments alone led to a conformational shift towards A-DNA. Such a shift was not observed here suggested that the reduced dielectric response of cellular environments is counteracted by non-specific interactions with protein crowders under in vivo conditions. Electronic supplementary material The online version of this article (10.1186/s13628-018-0048-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Asli Yildirim
- 1Department of Chemistry, Michigan State University, East Lansing, MI 48824 USA
| | - Nathalie Brenner
- 2Faculty of Mathematics and Natural Sciences, University of Düsseldorf, 40225 Düsseldorf, Germany.,3Department of Biochemistry & Molecular Biology, Michigan State University, 603 Wilson Road, Room BCH 218, East Lansing, MI 48824 USA
| | - Robert Sutherland
- 3Department of Biochemistry & Molecular Biology, Michigan State University, 603 Wilson Road, Room BCH 218, East Lansing, MI 48824 USA
| | - Michael Feig
- 3Department of Biochemistry & Molecular Biology, Michigan State University, 603 Wilson Road, Room BCH 218, East Lansing, MI 48824 USA
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178
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Residual Structure Accelerates Binding of Intrinsically Disordered ACTR by Promoting Efficient Folding upon Encounter. J Mol Biol 2018; 431:422-432. [PMID: 30528464 DOI: 10.1016/j.jmb.2018.12.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Revised: 11/10/2018] [Accepted: 12/03/2018] [Indexed: 11/21/2022]
Abstract
Intrinsically disordered proteins (IDPs) often fold into stable structures upon specific binding. The roles of residual structure of unbound IDPs in coupling binding and folding have been under much debate. While many studies emphasize the importance of conformational flexibility for IDP recognition, it was recently demonstrated that stabilization the N-terminal helix of intrinsically disordered ACTR accelerated its binding to another IDP, NCBD of the CREB-binding protein. To understand how enhancing ACTR helicity accelerates binding, we derived a series of topology-based coarse-grained models that mimicked various ACTR mutants with increasing helical contents and reproduced their NCBD binding affinities. Molecular dynamics simulations were then performed to sample hundreds of reversible coupled binding and folding transitions. The results show that increasing ACTR helicity does not alter the baseline mechanism of synergistic folding, which continues to follow "extended conformational selection" with multiple stages of selection and induced folding. Importantly, these coarse-grained models, while only calibrated based on binding thermodynamics, recapitulate the observed kinetic acceleration with increasing ACTR helicity. However, the residual helices do not enhance the association kinetics via more efficient seeding of productive collisions. Instead, they allow the nonspecific collision complexes to evolve more efficiently into the final bound and folded state, which is the primary source of accelerated association kinetics. Meanwhile, reduced dissociation kinetics with increasing ACTR helicity can be directly attributed to smaller entropic cost of forming the bound state. Altogether, this study provides important mechanistic insights into how residual structure may modulate thermodynamics and kinetics of IDP interactions.
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179
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Dhar J, Chakrabarti P. Structural motif, topi and its role in protein function and fibrillation. Mol Omics 2018; 14:247-256. [PMID: 29896602 DOI: 10.1039/c8mo00048d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A protein chain is arranged into regions in which the backbone is organized into regular patterns (of conformation and hydrogen bonding) to form the most common secondary structures, α-helix and β-sheet, which are interspersed by turns and more irregular loop regions. A structural motif, topi, is discussed in which a pair of 2-residue segments, each containing hydrogen-bonded five-membered fused-ring motifs, distant in sequence are linked to each other by a hydrogen bond. Though a small motif, it appears to be important in the context of local folding patterns of proteins and occurs near protein active sites. The motif shows quite significant residue preference, and a Cys (or Ser) occupying the second position may further stabilize the motif by forming an additional hydrogen bond across it. Remarkably, topi is found within disease causing misfolded proteins, such as the fibrilled form of Aβ42, and also across the interface between two protein chains. This motif may be an important component of fibrillation and useful for modeling loop regions.
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Affiliation(s)
- Jesmita Dhar
- Bioinformatics Centre, Bose Institute, P1/12 CIT Scheme VIIM, Kolkata 700054, India.
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180
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Olson MA. Conformational Selection of a Polyproline Peptide by Ebola Virus VP30. Proteomics 2018; 18:e1800081. [PMID: 30302912 DOI: 10.1002/pmic.201800081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Revised: 09/18/2018] [Indexed: 11/09/2022]
Abstract
An adaptive temperature-based replica-exchange simulation of a peptide extracted from the Ebola virus nucleoprotein containing a polyproline sequence motif is reported. The simulation results of applying the CHARMM36m force field with a generalized Born solvent model is presented. Conformational heterogeneity is described by potentials of mean force (PMFs) for a set of reaction coordinates that define the topological fold space. Starting from an extended backbone conformation of the peptide observed in an X-ray crystallographic assembly with the Ebola virus protein VP30, the PMFs report a conformational landscape populated by chain excursions to collapsed states with limited transitions to either an extended fold or a canonical polyproline type II helix. Clustering of the conformations and applying an elastic network interpolation model yield a multistep pathway of conformational selection that minimizes the net transition-state cost from the population hub to the bound state. Related difference between the pathway endpoints taken from the PMFs reveal a significant free-energy penalty in reaching a population shift. To evaluate sequence fitness of the Ebola virus peptide in generating probability distributions, two human sequence variants are modeled and are found to produce profiles that show extensive deviations, thus suggesting either dissimilar binding mechanisms or the lack of recognition by VP30.
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Affiliation(s)
- Mark A Olson
- Department of Cell Biology and Biochemistry, Molecular and Translational Sciences Division, USAMRIID, Frederick, MD, 21702, USA
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181
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Tarakanova A, Yeo GC, Baldock C, Weiss AS, Buehler MJ. Tropoelastin is a Flexible Molecule that Retains its Canonical Shape. Macromol Biosci 2018; 19:e1800250. [DOI: 10.1002/mabi.201800250] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 09/03/2018] [Indexed: 11/07/2022]
Affiliation(s)
- Anna Tarakanova
- Laboratory for Atomistic and Molecular Mechanics Department of Civil and Environmental Engineering Massachusetts Institute of Technology 02139 Cambridge MA USA
| | - Giselle C. Yeo
- School of Life and Environmental Sciences The University of Sydney 2006 Sydney NSW Australia
- Charles Perkins Centre The University of Sydney 2006 Sydney NSW Australia
| | - Clair Baldock
- Wellcome Trust Centre for Cell‐Matrix Research Division of Cell Matrix Biology and Regenerative Medicine School of Biological Sciences Manchester Academic Health Science Centre The University of Manchester M13 9PL Manchester UK
| | - Anthony S. Weiss
- School of Life and Environmental Sciences The University of Sydney 2006 Sydney NSW Australia
- Charles Perkins Centre The University of Sydney 2006 Sydney NSW Australia
- Bosch Institute The University of Sydney 2006 Sydney NSW Australia
| | - Markus J. Buehler
- Laboratory for Atomistic and Molecular Mechanics Department of Civil and Environmental Engineering Massachusetts Institute of Technology 02139 Cambridge MA USA
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182
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Sitthiyotha T, Pichyangkura R, Chunsrivirot S. Molecular dynamics provides insight into how N251A and N251Y mutations in the active site of Bacillus licheniformis RN-01 levansucrase disrupt production of long-chain levan. PLoS One 2018; 13:e0204915. [PMID: 30278092 PMCID: PMC6168164 DOI: 10.1371/journal.pone.0204915] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Accepted: 09/17/2018] [Indexed: 12/11/2022] Open
Abstract
Produced by levansucrase, levan and levan oligosaccharides (GFn) have potential applications in food and pharmaceutical industries such as prebiotics, anti-tumor and anti-inflammatory agents. Previous study reported that Bacillus licheniformis RN-01 levansucrase could produce levan oligosaccharides and long-chain levan. However, its N251A and N251Y mutants could effectively produce short-chain oligosaccharides upto GF3, but they could not produce long-chain levan. We hypothesized that these mutations probably reduced GF3 binding affinity in levansucrase active site that contains fructosyl-Asp93 intermediate and caused GF3 to be in an unfavorable orientation for transfructosylation; therefore, levansucrase could not effectively extend GF3 by one fructosyl residue to produce GF4 and subsequently long-chain levan. However, these mutations probably did not significantly reduce binding affinity or drastically change orientation of GF2; therefore, levansucrase could still extend GF2 to produce GF3. Using this hypothesis, we employed molecular dynamics to investigate effects of these mutations on GF2/GF3 binding in levansucrase active site. Our results reasonably support this hypothesis as N251A and N251Y mutations did not significantly reduce GF2 binding affinity, as calculated by MM-GBSA technique and hydrogen bond occupations, or drastically change orientation of GF2 in levansucrase active site, as measured by distance between atoms necessary for transfructosylation. However, these mutations drastically decreased GF3 binding affinity and caused GF3 to be in an unfavorable orientation for transfructosylation. Furthermore, the free energy decomposition and hydrogen bond occupation results suggest the importance of Arg255 in GF2/GF3 binding in levansucrase active site. This study provides important and novel insight into the effects of N251A and N251Y mutations on GF2/GF3 binding in levansucrase active site and how they may disrupt production of long-chain levan. This knowledge could be beneficial in designing levansucrase to efficiently produce levan oligosaccharides with desired length.
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Affiliation(s)
- Thassanai Sitthiyotha
- Department of Biochemistry, Faculty of Science, Chulalongkorn University, Pathumwan, Bangkok, Thailand
- Structural and Computational Biology Research Group, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Pathumwan, Bangkok, Thailand
| | - Rath Pichyangkura
- Department of Biochemistry, Faculty of Science, Chulalongkorn University, Pathumwan, Bangkok, Thailand
| | - Surasak Chunsrivirot
- Department of Biochemistry, Faculty of Science, Chulalongkorn University, Pathumwan, Bangkok, Thailand
- Structural and Computational Biology Research Group, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Pathumwan, Bangkok, Thailand
- * E-mail:
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183
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Dan A, Chen HF. Secondary structures transition of tau protein with intrinsically disordered proteins specific force field. Chem Biol Drug Des 2018; 93:242-253. [PMID: 30259679 DOI: 10.1111/cbdd.13407] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 09/13/2018] [Accepted: 09/15/2018] [Indexed: 02/06/2023]
Abstract
Microtubule-associated Tau protein plays a key role in assembling microtubule and modulating the functional organization of the neuron and developing axonal morphology, growth, and polarity. The pathological Tau can aggregate into cross-beta amyloid as one of the hallmarks for Alzheimer's disease (AD). Therefore, one of the top priorities in AD research is to figure out the structural model of Tau aggregation and to screen the inhibitors. The latest generation intrinsically disordered protein specific force field ff14IDPSFF significantly improved the distributions of heterogeneous conformations for intrinsically disordered proteins (IDPs). Here, the molecular dynamics (MD) simulations with three force fields of ff14SB, ff14IDPs, and ff14IDPSFF were employed to investigate the secondary structures transition of Tau (267-312) fragment. The results indicate that ff14IDPSFF can generate more heterogeneous conformers, and the predicted secondary structural distribution is closer to that of the experimental observation. In addition, predicted secondary chemical shifts from ff14IDPSFF are the most approach to those of experiment. Secondary structures transition kinetics for Tau(267-312) with ff14IDPSFF shows that the secondary structures were gradually transformed from α-helix to β-strand and the β-strand located at the regions of the residues 274-280 and residues 305-311. Besides, the driving force for the secondary structures transition of Tau(267-312) is mainly hydrophobic interactions which located at hexa-peptides 275 VQIINK280 and 306 VQIVYK311 . Secondary structure transition of Tau protein can give insight into the aggregation mechanism for AD.
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Affiliation(s)
- Aohuan Dan
- State Key Laboratory of Microbial Metabolism, Department of Bioinformatics and Biostatistics, SJTU-Yale Joint Center for Biostatistics, National Experimental Teaching Center for Life Sciences and Biotechnology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Hai-Feng Chen
- State Key Laboratory of Microbial Metabolism, Department of Bioinformatics and Biostatistics, SJTU-Yale Joint Center for Biostatistics, National Experimental Teaching Center for Life Sciences and Biotechnology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China.,Shanghai Center for Bioinformation Technology, Shanghai, China
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184
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Li J, Zhang H, Liu G, Tang Y, Tu Y, Li W. Computational Insight Into Vitamin K 1 ω-Hydroxylation by Cytochrome P450 4F2. Front Pharmacol 2018; 9:1065. [PMID: 30319412 PMCID: PMC6167488 DOI: 10.3389/fphar.2018.01065] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 09/03/2018] [Indexed: 12/28/2022] Open
Abstract
Vitamin K1 (VK1) plays an important role in the modulation of bleeding disorders. It has been reported that ω-hydroxylation on the VK1 aliphatic chain is catalyzed by cytochrome P450 4F2 (CYP4F2), an enzyme responsible for the metabolism of eicosanoids. However, the mechanism of VK1 ω-hydroxylation by CYP4F2 has not been disclosed. In this study, we employed a combination of quantum mechanism (QM) calculations, homology modeling, molecular docking, molecular dynamics (MD) simulations, and combined quantum mechanism/molecular mechanism (QM/MM) calculations to investigate the metabolism profile of VK1 ω-hydroxylation. QM calculations based on the truncated VK1 model show that the energy barrier for ω-hydroxylation is about 6-25 kJ/mol higher than those at other potential sites of metabolism. However, results from the MD simulations indicate that hydroxylation at the ω-site is more favorable than at the other potential sites, which is in accordance with the experimental observation. The evaluation of MD simulations was further endorsed by the QM/MM calculation results. Our studies thus suggest that the active site residues of CYP4F2 play a determinant role in the ω-hydroxylation. Our results provide structural insights into the mechanism of VK1 ω-hydroxylation by CYP4F2 at the atomistic level and are helpful not only for characterizing the CYP4F2 functions but also for looking into the ω-hydroxylation mediated by other CYP4 enzymes.
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Affiliation(s)
- Junhao Li
- Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, Shanghai, China.,Department of Theoretical Chemistry and Biology, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), KTH Royal Institute of Technology, Stockholm, Sweden
| | - Hongxiao Zhang
- Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, Shanghai, China
| | - Guixia Liu
- Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, Shanghai, China
| | - Yun Tang
- Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, Shanghai, China
| | - Yaoquan Tu
- Department of Theoretical Chemistry and Biology, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), KTH Royal Institute of Technology, Stockholm, Sweden
| | - Weihua Li
- Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, Shanghai, China
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185
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Sala D, Musiani F, Rosato A. Application of Molecular Dynamics to the Investigation of Metalloproteins Involved in Metal Homeostasis. Eur J Inorg Chem 2018. [DOI: 10.1002/ejic.201800602] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Davide Sala
- Magnetic Resonance Center (CERM); University of Florence; Via Luigi Sacconi 6 50019 Sesto Fiorentino Italy
| | - Francesco Musiani
- Laboratory of Bioinorganic Chemistry; Department of Pharmacy and Biotechnology; University of Bologna; Viale Giuseppe Fanin 40, I 40127 Bologna Italy
| | - Antonio Rosato
- Magnetic Resonance Center (CERM); University of Florence; Via Luigi Sacconi 6 50019 Sesto Fiorentino Italy
- Consorzio Interuniversitario di Risonanze Magnetiche di Metallo Proteine; Via Luigi Sacconi 6 50019 Sesto Fiorentino Italy
- Department of Chemistry; University of Florence; Via della Lastruccia 3 50019 Sesto Fiorentino Italy
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186
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Ren J, Dsouza NR, Deng H, Lee H, Bouvier M, Johnson ME. Discovery of small molecule inhibitors of adenovirus by disrupting E3-19K/HLA-A2 interactions. Bioorg Med Chem Lett 2018; 28:2837-2841. [PMID: 30077568 DOI: 10.1016/j.bmcl.2018.07.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 07/24/2018] [Accepted: 07/26/2018] [Indexed: 11/30/2022]
Abstract
The binding of the adenovirus (Ad) protein E3-19K with the human leukocyte antigen (HLA) plays an important role in Ad infections, which is the causative agent of a series of gastrointestinal, respiratory and ocular diseases. The objective of this research is to evaluate the essential interactions between E3-19K and HLA-A2 using the X-ray crystal structure of the E3-19K/HLA-A2 complex, and to identify small molecules that could potentially disrupt their binding. Computational methods, including molecular dynamic simulations, MM/GBSA calculations, and computational solvent mapping, were implemented to determine potential binding site(s) for small molecules. The previous experimentally determined hot spot residues, Q54 and E177 in HLA-A2, were also predicted to be the dominant residues for binding to E3-19K by our theoretical calculations. Several other residues were also found to play pivotal roles for the binding of E3-19K with HLA-A2. Residues adjacent to E177, including Q54 and several other residues theoretically predicted to be crucial in HLA-A2 were selected as a potential binding pocket to perform virtual screening with 1200 compounds from the Prestwick library. Seven hits were validated by surface plasmon resonance (SPR) as binders to HLA-A2 as a first step in identifying molecules that can perturb its association with the Ad E3-19K protein.
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Affiliation(s)
- Jinhong Ren
- Center for Biomolecular Sciences, University of Illinois at Chicago, 900 S. Ashland Ave, Chicago, IL 60607, USA
| | - Nikita R Dsouza
- Department of Bioengineering, University of Illinois at Chicago, 835 S Wolcott Ave, Chicago, IL 60612, USA
| | - Hui Deng
- Department of Microbiology and Immunology, University of Illinois at Chicago, 835 S. Wolcott Ave, Chicago, IL 60612, USA
| | - Hyun Lee
- Center for Biomolecular Sciences, University of Illinois at Chicago, 900 S. Ashland Ave, Chicago, IL 60607, USA; Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, 900 S. Ashland Ave, Chicago, IL 60607, USA; Biophysics Core, Research Resources Center, University of Illinois at Chicago, 1100 S. Ashland Ave, Chicago, IL 60607, USA
| | - Marlene Bouvier
- Department of Microbiology and Immunology, University of Illinois at Chicago, 835 S. Wolcott Ave, Chicago, IL 60612, USA
| | - Michael E Johnson
- Center for Biomolecular Sciences, University of Illinois at Chicago, 900 S. Ashland Ave, Chicago, IL 60607, USA; Department of Bioengineering, University of Illinois at Chicago, 835 S Wolcott Ave, Chicago, IL 60612, USA; Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, 900 S. Ashland Ave, Chicago, IL 60607, USA.
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187
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Chen J, Liu X, Chen J. Atomistic Peptide Folding Simulations Reveal Interplay of Entropy and Long-Range Interactions in Folding Cooperativity. Sci Rep 2018; 8:13668. [PMID: 30209295 PMCID: PMC6135771 DOI: 10.1038/s41598-018-32028-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 08/30/2018] [Indexed: 11/23/2022] Open
Abstract
Understanding how proteins fold has remained a problem of great interest in biophysical research. Atomistic computer simulations using physics-based force fields can provide important insights on the interplay of different interactions and energetics and their roles in governing the folding thermodynamics and mechanism. In particular, generalized Born (GB)-based implicit solvent force fields can be optimized to provide an appropriate balance between solvation and intramolecular interactions and successfully recapitulate experimental conformational equilibria for a set of helical and β-hairpin peptides. Here, we further demonstrate that key thermodynamic properties and their temperature dependence obtained from replica exchange molecular dynamics simulations of these peptides are in quantitative agreement with experimental results. Useful lessons can be learned on how the interplay of entropy and sequentially long-range interactions governs the mechanism and cooperativity of folding. These results highlight the great potential of high-quality implicit solvent force fields for studying protein folding and large-scale conformational transitions.
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Affiliation(s)
- Jianlin Chen
- Department of Hematology, The Central Hospital of Taizhou, Taizhou, Zhejiang, 318000, P.R. China
| | - Xiaorong Liu
- Department of Chemistry, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Jianhan Chen
- Department of Chemistry, University of Massachusetts Amherst, Amherst, MA, 01003, USA. .,Department of Biochemistry and Molecular Biology, University of Massachusetts Amherst, Amherst, MA, 01003, USA.
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188
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Frank F, Okafor CD, Ortlund EA. The first crystal structure of a DNA-free nuclear receptor DNA binding domain sheds light on DNA-driven allostery in the glucocorticoid receptor. Sci Rep 2018; 8:13497. [PMID: 30201977 PMCID: PMC6131172 DOI: 10.1038/s41598-018-31812-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 08/22/2018] [Indexed: 12/05/2022] Open
Abstract
The glucocorticoid receptor (GR) is a steroid hormone receptor of the nuclear receptor family that regulates gene expression in response to glucocorticoid hormone signaling. Interaction with specific GR DNA binding sequences causes conformational changes in the GR DNA binding domain (DBD) that result in recruitment of specific sets of co-regulators that determine transcriptional outcomes. We have solved the crystal structure of GR DBD in its DNA-free state, the first such crystal structure from any nuclear receptor. In contrast to previous NMR structures, this crystal structure reveals that free GR DBD adopts a conformation very similar to DNA-bound states. The lever arm region is the most variable element in the free GR DBD. Molecular dynamics of the free GR DBD as well as GR DBD bound to activating and repressive DNA elements confirm lever arm flexibility in all functional states. Cluster analysis of lever arm conformations during simulations shows that DNA binding and dimerization cause a reduction in the number of conformations sampled by the lever arm. These results reveal that DNA binding and dimerization drive conformational selection in the GR DBD lever arm region and show how DNA allosterically controls GR structure and dynamics.
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Affiliation(s)
- Filipp Frank
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - C Denise Okafor
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Eric A Ortlund
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, 30322, USA.
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189
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Woodard J, Srivastava KR, Rahamim G, Grupi A, Hogan S, Witalka DJ, Nawrocki G, Haas E, Feig M, Lapidus LJ. Intramolecular Diffusion in α-Synuclein: It Depends on How You Measure It. Biophys J 2018; 115:1190-1199. [PMID: 30224053 DOI: 10.1016/j.bpj.2018.08.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 08/09/2018] [Accepted: 08/21/2018] [Indexed: 10/28/2022] Open
Abstract
Intramolecular protein diffusion, the motion of one part of the polypeptide chain relative to another part, is a fundamental aspect of protein folding and may modulate amyloidogenesis of disease-associated intrinsically disordered proteins. Much work has determined such diffusion coefficients using a variety of probes, but there has been an apparent discrepancy between measurements using long-range probes, such as fluorescence resonance energy transfer, and short-range probes, such as Trp-Cys quenching. In this work, we make both such measurements on the same protein, α-synuclein, and confirm that such discrepancy exists. Molecular dynamics simulations suggest that such differences result from a diffusion coefficient that depends on the spatial distance between probes. Diffusional estimates in good quantitative agreement with experiment are obtained by accounting for the distinct distance ranges probed by fluorescence resonance energy transfer and Trp-Cys quenching.
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Affiliation(s)
- Jaie Woodard
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan
| | - Kinshuk R Srivastava
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan
| | - Gil Rahamim
- The Goodman Faculty of Life Science, Bar-Ilan University, Ramat Gan, Israel
| | - Asaf Grupi
- The Goodman Faculty of Life Science, Bar-Ilan University, Ramat Gan, Israel
| | - Steven Hogan
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan
| | - David J Witalka
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan
| | - Grzegorz Nawrocki
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan
| | - Elisha Haas
- The Goodman Faculty of Life Science, Bar-Ilan University, Ramat Gan, Israel
| | - Michael Feig
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan
| | - Lisa J Lapidus
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan; Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan.
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190
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Wang Y, Tian P, Boomsma W, Lindorff-Larsen K. Monte Carlo Sampling of Protein Folding by Combining an All-Atom Physics-Based Model with a Native State Bias. J Phys Chem B 2018; 122:11174-11185. [DOI: 10.1021/acs.jpcb.8b06335] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yong Wang
- Structural Biology and NMR Laboratory, Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark
| | - Pengfei Tian
- Structural Biology and NMR Laboratory, Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Wouter Boomsma
- Department of Computer Science, University of Copenhagen, 2100 Copenhagen Ø, Denmark
| | - Kresten Lindorff-Larsen
- Structural Biology and NMR Laboratory, Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark
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191
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Hayashi T, Inoue M, Yasuda S, Petretto E, Škrbić T, Giacometti A, Kinoshita M. Universal effects of solvent species on the stabilized structure of a protein. J Chem Phys 2018; 149:045105. [PMID: 30068177 DOI: 10.1063/1.5042111] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We investigate the effects of solvent specificities on the stability of the native structure (NS) of a protein on the basis of our free-energy function (FEF). We use CPB-bromodomain (CBP-BD) and apoplastocyanin (apoPC) as representatives of the protein universe and water, methanol, ethanol, and cyclohexane as solvents. The NSs of CBP-BD and apoPC consist of 66% α-helices and of 35% β-sheets and 4% α-helices, respectively. In order to assess the structural stability of a given protein immersed in each solvent, we contrast the FEF of its NS against that of a number of artificially created, misfolded decoys possessing the same amino-acid sequence but significantly different topology and α-helix and β-sheet contents. In the FEF, we compute the solvation entropy using the morphometric approach combined with the integral equation theories, and the change in electrostatic (ES) energy upon the folding is obtained by an explicit atomistic but simplified calculation. The ES energy change is represented by the break of protein-solvent hydrogen bonds (HBs), formation of protein intramolecular HBs, and recovery of solvent-solvent HBs. Protein-solvent and solvent-solvent HBs are absent in cyclohexane. We are thus able to separately evaluate the contributions to the structural stability from the entropic and energetic components. We find that for both CBP-BD and apoPC, the energetic component dominates in methanol, ethanol, and cyclohexane, with the most stable structures in these solvents sharing the same characteristics described as an association of α-helices. In particular, those in the two alcohols are identical. In water, the entropic component is as strong as or even stronger than the energetic one, with a large gain of translational, configurational entropy of water becoming crucially important so that the relative contents of α-helix and β-sheet and the content of total secondary structures are carefully selected to achieve sufficiently close packing of side chains. If the energetic component is excluded for a protein in water, the priority is given to closest side-chain packing, giving rise to the formation of a structure with very low α-helix and β-sheet contents. Our analysis, which requires minimal computational effort, can be applied to any protein immersed in any solvent and provides robust predictions that are quite consistent with the experimental observations for proteins in different solvent environments, thus paving the way toward a more detailed understanding of the folding process.
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Affiliation(s)
- Tomohiko Hayashi
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Masao Inoue
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Satoshi Yasuda
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Emanuele Petretto
- Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca' Foscari Venezia, Edificio Alfa Campus Scientifico, Via Torino 155, Venezia-Mestre I-3010, Italy
| | - Tatjana Škrbić
- Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca' Foscari Venezia, Edificio Alfa Campus Scientifico, Via Torino 155, Venezia-Mestre I-3010, Italy
| | - Achille Giacometti
- Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca' Foscari Venezia, Edificio Alfa Campus Scientifico, Via Torino 155, Venezia-Mestre I-3010, Italy
| | - Masahiro Kinoshita
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
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192
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Kar RK, Brender JR, Ghosh A, Bhunia A. Nonproductive Binding Modes as a Prominent Feature of Aβ 40 Fiber Elongation: Insights from Molecular Dynamics Simulation. J Chem Inf Model 2018; 58:1576-1586. [PMID: 30047732 DOI: 10.1021/acs.jcim.8b00169] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The formation of amyloid fibers has been implicated in a number of neurodegenerative diseases. The growth of amyloid fibers is strongly thermodynamically favorable, but kinetic traps exist where the incoming monomer binds in an incompatible conformation that blocks further elongation. Unfortunately, this process is difficult to follow experimentally at the atomic level. It is also too complex to simulate in full detail and to date has been explored either through coarse-grained simulations, which may miss many important interactions, or full atomic simulations, in which the incoming peptide is constrained to be near the ideal fiber geometry. Here we use an alternate approach starting from a docked complex in which the monomer is from an experimental NMR structure of one of the major conformations in the unbound ensemble, a largely unstructured peptide with the central hydrophobic region in a 310 helix. A 1000 ns full atomic simulation in explicit solvent shows the formation of a metastable intermediate by sequential, concerted movements of both the fiber and the monomer. A Markov state model shows that the unfolded monomer is trapped at the end of the fiber in a set of interconverting antiparallel β-hairpin conformations. The simulation here may serve as a model for the binding of other non-β-sheet conformations to amyloid fibers.
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Affiliation(s)
- Rajiv K Kar
- Department of Biophysics , Bose Institute , P-1/12 CIT Scheme VII (M) , Kolkata 700054 , India
| | - Jeffrey R Brender
- Radiation Biology Branch , National Institutes of Health , Bethesda , Maryland 20814 , United States
| | - Anirban Ghosh
- Department of Biophysics , Bose Institute , P-1/12 CIT Scheme VII (M) , Kolkata 700054 , India
| | - Anirban Bhunia
- Department of Biophysics , Bose Institute , P-1/12 CIT Scheme VII (M) , Kolkata 700054 , India
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193
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Kondalaji SG, Khakinejad M, Valentine SJ. Comprehensive Peptide Ion Structure Studies Using Ion Mobility Techniques: Part 3. Relating Solution-Phase to Gas-Phase Structures. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2018; 29:1665-1677. [PMID: 29858839 PMCID: PMC6525623 DOI: 10.1007/s13361-018-1996-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 05/02/2018] [Accepted: 05/02/2018] [Indexed: 05/16/2023]
Abstract
Molecular dynamics (MD) simulations have been utilized to study peptide ion conformer establishment during the electrospray process. An explicit water model is used for nanodroplets containing a model peptide and hydronium ions. Simulations are conducted at 300 K for two different peptide ion charge configurations and for droplets containing varying numbers of hydronium ions. For all conditions, modeling has been performed until production of the gas-phase ions and the resultant conformers have been compared to proposed gas-phase structures. The latter species were obtained from previous studies in which in silico candidate structures were filtered according to ion mobility and hydrogen-deuterium exchange (HDX) reactivity matches. Results from the present study present three key findings namely (1) the evidence from ion production modeling supports previous structure refinement studies based on mobility and HDX reactivity matching, (2) the modeling of the electrospray process is significantly improved by utilizing initial droplets existing below but close to the calculated Rayleigh limit, and (3) peptide ions in the nanodroplets sample significantly different conformers than those in the bulk solution due to altered physicochemical properties of the solvent. Graphical Abstract ᅟ.
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Affiliation(s)
- Samaneh Ghassabi Kondalaji
- Department of Chemistry, West Virginia University, Morgantown, WV, 26506, USA
- Department of Biophysics, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Mahdiar Khakinejad
- Department of Chemistry, West Virginia University, Morgantown, WV, 26506, USA
- Department of Biophysics, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Stephen J Valentine
- Department of Chemistry, West Virginia University, Morgantown, WV, 26506, USA.
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194
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Newkirk ML, Rubenstein KJ, Kim JY, Labrecque CL, Airas J, Taylor CA, Evans HD, McKoy Q, Parish CA, Pollock JA. Analysis of MEMO1 Binding Specificity for ErbB2 Using Fluorescence Polarization and Molecular Dynamics Simulations. Biochemistry 2018; 57:5169-5181. [DOI: 10.1021/acs.biochem.8b00582] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Madeline L. Newkirk
- Department of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Kristen J. Rubenstein
- Department of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Jessica Y. Kim
- Department of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Courtney L. Labrecque
- Department of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Justin Airas
- Department of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Cooper A. Taylor
- Department of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Hunter D. Evans
- Department of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Quincy McKoy
- Department of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Carol A. Parish
- Department of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Julie A. Pollock
- Department of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
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195
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Gholami S, Nenov A, Rivalta I, Bocola M, Bordbar AK, Schwaneberg U, Davari MD, Garavelli M. Theoretical Model of the Protochlorophyllide Oxidoreductase from a Hierarchy of Protocols. J Phys Chem B 2018; 122:7668-7681. [PMID: 29996651 DOI: 10.1021/acs.jpcb.8b04231] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The enzyme protochlorophyllide oxidoreductase (LPOR) catalyzes the light-driven reduction of protochlorophyllide (Pchlide), a crucial step in chlorophyll biosynthesis. Molecular understanding of the photocatalytic mechanism of LPOR is essential for harnessing light energy to mediate enzymatic reactions. The absence of X-ray crystal structure has promoted the development of LPOR homology models that lack a catalytically competent active site and could not explain the variously reported spectroscopic evidence, including time-resolved optical spectroscopy data. We have refined previous structural models to account for the catalytic active site and the characteristic experimental spectral features of Pchlide binding, including the 26 cm-1 red shift of the C13(1) carbonyl stretch vibration in the mid-infrared (IR) and the 12 nm red shift of the Q x electronic band. A hierarchy of theoretical methods, including homology modeling, molecular dynamics simulations, hybrid quantum mechanics [(TD-)DFT]/molecular mechanics [AMBER] calculations, and computational vibrational and electronic spectroscopies, have been combined in an iterative protocol to reproduce experimental evidence and to predict ultrafast transient IR spectroscopic fingerprints associated with the catalytic process. The successful application to the LPOR enzyme indicates that the presented hierarchical protocol provides a general workflow to protein structure refinement.
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Affiliation(s)
- Samira Gholami
- Department of Chemistry , University of Isfahan , Isfahan 81746-73441 , Iran.,Dipartimento di Chimica Industriale , Università degli Studi di Bologna , Viale del Risorgimento 4 , I-40136 Bologna , Italy
| | - Artur Nenov
- Dipartimento di Chimica Industriale , Università degli Studi di Bologna , Viale del Risorgimento 4 , I-40136 Bologna , Italy
| | - Ivan Rivalta
- Université de Lyon , École Normale Supérieure de Lyon, CNRS, Université Claude Bernard Lyon 1, Laboratoire de Chimie UMR 5182, F-69342 , Lyon , France
| | - Marco Bocola
- Institute of Biotechnology , RWTH Aachen University , Worringer Weg 3 , 52074 Aachen , Germany
| | - A Khalegh Bordbar
- Department of Chemistry , University of Isfahan , Isfahan 81746-73441 , Iran
| | - Ulrich Schwaneberg
- Institute of Biotechnology , RWTH Aachen University , Worringer Weg 3 , 52074 Aachen , Germany.,DWI-Leibniz Institute for Interactive Materials , Forckenbeckstraße 50 , 52056 Aachen , Germany
| | - Mehdi D Davari
- Institute of Biotechnology , RWTH Aachen University , Worringer Weg 3 , 52074 Aachen , Germany
| | - Marco Garavelli
- Dipartimento di Chimica Industriale , Università degli Studi di Bologna , Viale del Risorgimento 4 , I-40136 Bologna , Italy
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196
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Shao Q, Zhu W. The effects of implicit modeling of nonpolar solvation on protein folding simulations. Phys Chem Chem Phys 2018; 20:18410-18419. [PMID: 29946610 DOI: 10.1039/c8cp03156h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Implicit solvent models, in which the polar and nonpolar solvation free-energies of solute molecules are treated separately, have been widely adopted for molecular dynamics simulation of protein folding. While the development of the implicit models is mainly focused on the methodological improvement and key parameter optimization for polar solvation, nonpolar solvation has been either ignored or described by a simplistic surface area (SA) model. In this work, we performed the folding simulations of multiple β-hairpin and α-helical proteins with varied surface tension coefficients embedded in the SA model to clearly demonstrate the effects of nonpolar solvation treated by a popular SA model on protein folding. The results indicate that the change in the surface tension coefficient does not alter the ability of implicit solvent simulations to reproduce a protein native structure but indeed controls the components of the equilibrium conformational ensemble and modifies the energetic characterization of the folding transition pathway. The suitably set surface tension coefficient can yield explicit solvent simulations and/or experimentally suggested folding mechanism of protein. In addition, the implicit treatment of both polar and nonpolar components of solvation free-energy contributes to the overestimation of the secondary structure in implicit solvent simulations.
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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, 555 Zuchongzhi Road, Shanghai, 201203, China.
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197
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Sun X, Yan X, Zhuo W, Gu J, Zuo K, Liu W, Liang L, Gan Y, He G, Wan H, Gou X, Shi H, Hu J. PD-L1 Nanobody Competitively Inhibits the Formation of the PD-1/PD-L1 Complex: Comparative Molecular Dynamics Simulations. Int J Mol Sci 2018; 19:E1984. [PMID: 29986511 PMCID: PMC6073277 DOI: 10.3390/ijms19071984] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 07/02/2018] [Accepted: 07/04/2018] [Indexed: 12/22/2022] Open
Abstract
The anti-PD-L1 monoclonal antibody (mAb) targeting PD-1/PD-L1 immune checkpoint has achieved outstanding results in clinical application and has become one of the most popular anti-cancer drugs. The mechanism of molecular recognition and inhibition of PD-L1 mAbs is not yet clear, which hinders the subsequent antibody design and modification. In this work, the trajectories of PD-1/PD-L1 and nanobody/PD-L1 complexes were obtained via comparative molecular dynamics simulations. Then, a series of physicochemical parameters including hydrogen bond, dihedral angle distribution, pKa value and binding free energy, and so forth, were all comparatively analyzed to investigate the recognition difference between PD-L1 and PD-1 and nanobody. Both LR113 (the amino acid residues in PD-L1 are represented by the lower left sign of L) and LR125 residues of PD-L1 undergo significant conformational change after association with mAbs, which dominates a strong electrostatic interaction. Solvation effect analysis revealed that solvent-water enhanced molecular recognition between PD-L1 and nanobody. By combining the analyses of the time-dependent root mean squared fluctuation (RMSF), free energy landscape, clustering and energy decomposition, the potential inhibition mechanism was proposed that the nanobody competitively and specifically bound to the β-sheet groups of PD-L1, reduced the PD-L1’s flexibility and finally blocked the formation of PD-1/PD-L1 complex. Based on the simulation results, site-directed mutagenesis of ND99 (the amino acid residues in Nano are displayed by the lower left sign of N) and NQ116 in the nanobody may be beneficial for improving antibody activity. This work offers some structural guidance for the design and modification of anticancer mAbs based on the structure of the PD-1/PD-L1 complex.
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Affiliation(s)
- Xin Sun
- College of Pharmacy and Biological Engineering, Sichuan Industrial Institute of Antibiotics, Key Laboratory of Medicinal and Edible Plants Resources Development of Sichuan Education Department, Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Chengdu University, Chengdu 610106, China.
| | - Xiao Yan
- College of Pharmacy and Biological Engineering, Sichuan Industrial Institute of Antibiotics, Key Laboratory of Medicinal and Edible Plants Resources Development of Sichuan Education Department, Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Chengdu University, Chengdu 610106, China.
| | - Wei Zhuo
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
| | - Jinke Gu
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
| | - Ke Zuo
- College of Pharmacy and Biological Engineering, Sichuan Industrial Institute of Antibiotics, Key Laboratory of Medicinal and Edible Plants Resources Development of Sichuan Education Department, Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Chengdu University, Chengdu 610106, China.
| | - Wei Liu
- College of Pharmacy and Biological Engineering, Sichuan Industrial Institute of Antibiotics, Key Laboratory of Medicinal and Edible Plants Resources Development of Sichuan Education Department, Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Chengdu University, Chengdu 610106, China.
| | - Li Liang
- College of Pharmacy and Biological Engineering, Sichuan Industrial Institute of Antibiotics, Key Laboratory of Medicinal and Edible Plants Resources Development of Sichuan Education Department, Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Chengdu University, Chengdu 610106, China.
| | - Ya Gan
- College of Pharmacy and Biological Engineering, Sichuan Industrial Institute of Antibiotics, Key Laboratory of Medicinal and Edible Plants Resources Development of Sichuan Education Department, Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Chengdu University, Chengdu 610106, China.
| | - Gang He
- College of Pharmacy and Biological Engineering, Sichuan Industrial Institute of Antibiotics, Key Laboratory of Medicinal and Edible Plants Resources Development of Sichuan Education Department, Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Chengdu University, Chengdu 610106, China.
| | - Hua Wan
- College of Mathematics and Informatics, South China Agricultural University, Guangzhou 510642, China.
| | - Xiaojun Gou
- College of Pharmacy and Biological Engineering, Sichuan Industrial Institute of Antibiotics, Key Laboratory of Medicinal and Edible Plants Resources Development of Sichuan Education Department, Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Chengdu University, Chengdu 610106, China.
| | - Hubing Shi
- Laboratory of tumor targeted and immune therapy, Clinical Research Center for Breast, State Key Laboratory of Biotherapy, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu 610041, China.
| | - Jianping Hu
- College of Pharmacy and Biological Engineering, Sichuan Industrial Institute of Antibiotics, Key Laboratory of Medicinal and Edible Plants Resources Development of Sichuan Education Department, Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Chengdu University, Chengdu 610106, China.
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198
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Liu H, Guo X, Han J, Luo R, Chen HF. Order-disorder transition of intrinsically disordered kinase inducible transactivation domain of CREB. J Chem Phys 2018; 148:225101. [PMID: 29907037 DOI: 10.1063/1.5027869] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Transcription factor cyclic Adenosine monophosphate response-element binding protein plays a critical role in the cyclic AMP response pathway via its intrinsically disordered kinase inducible transactivation domain (KID). KID is one of the most studied intrinsically disordered proteins (IDPs), although most previous studies focus on characterizing its disordered state structures. An interesting question that remains to be answered is how the order-disorder transition occurs at experimental conditions. Thanks to the newly developed IDP-specific force field ff14IDPSFF, the quality of conformer sampling for IDPs has been dramatically improved. In this study, molecular dynamics (MD) simulations were used to study the order-to-disorder transition kinetics of KID based on the good agreement with the experiment on its disordered-state properties. Specifically, we tested four force fields, ff99SBildn, ff99IDPs, ff14IDPSFF, and ff14IDPs in the simulations of KID and found that ff14IDPSFF can generate more diversified disordered conformers and also reproduce more accurate experimental secondary chemical shifts. Kinetics analysis of MD simulations demonstrates that the order-disorder transition of KID obeys the first-order kinetics, and the transition nucleus is I127/L128/L141. The possible transition pathways from the nucleus to the last folded residues were identified as I127-R125-L138-L141-S143-A145 and L128-R125-L138-L141-S143-A145 based on a residue-level dynamical network analysis. These computational studies not only provide testable prediction/hypothesis on the order-disorder transition of KID but also confirm that the ff14IDPSFF force field can be used to explore the correlation between the structure and function of IDPs.
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Affiliation(s)
- Hao Liu
- State Key Laboratory of Microbial Metabolism, Department of Bioinformatics and Biostatistics, SJTU-Yale Joint Center for Biostatistics, National Experimental Teaching Center for Life Sciences and Biotechnology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Xiang Guo
- State Key Laboratory of Microbial Metabolism, Department of Bioinformatics and Biostatistics, SJTU-Yale Joint Center for Biostatistics, National Experimental Teaching Center for Life Sciences and Biotechnology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Jingcheng Han
- State Key Laboratory of Microbial Metabolism, Department of Bioinformatics and Biostatistics, SJTU-Yale Joint Center for Biostatistics, National Experimental Teaching Center for Life Sciences and Biotechnology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Ray Luo
- Departments of Molecular Biology and Biochemistry, Chemical Engineering and Materials Science, Biomedical Engineering, University of California, Irvine, California 92697-3900, USA
| | - Hai-Feng Chen
- State Key Laboratory of Microbial Metabolism, Department of Bioinformatics and Biostatistics, SJTU-Yale Joint Center for Biostatistics, National Experimental Teaching Center for Life Sciences and Biotechnology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
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199
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Czaplewski C, Karczyńska A, Sieradzan AK, Liwo A. UNRES server for physics-based coarse-grained simulations and prediction of protein structure, dynamics and thermodynamics. Nucleic Acids Res 2018; 46:W304-W309. [PMID: 29718313 PMCID: PMC6031057 DOI: 10.1093/nar/gky328] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 04/12/2018] [Accepted: 04/18/2018] [Indexed: 12/24/2022] Open
Abstract
A server implementation of the UNRES package (http://www.unres.pl) for coarse-grained simulations of protein structures with the physics-based UNRES model, coined a name UNRES server, is presented. In contrast to most of the protein coarse-grained models, owing to its physics-based origin, the UNRES force field can be used in simulations, including those aimed at protein-structure prediction, without ancillary information from structural databases; however, the implementation includes the possibility of using restraints. Local energy minimization, canonical molecular dynamics simulations, replica exchange and multiplexed replica exchange molecular dynamics simulations can be run with the current UNRES server; the latter are suitable for protein-structure prediction. The user-supplied input includes protein sequence and, optionally, restraints from secondary-structure prediction or small x-ray scattering data, and simulation type and parameters which are selected or typed in. Oligomeric proteins, as well as those containing D-amino-acid residues and disulfide links can be treated. The output is displayed graphically (minimized structures, trajectories, final models, analysis of trajectory/ensembles); however, all output files can be downloaded by the user. The UNRES server can be freely accessed at http://unres-server.chem.ug.edu.pl.
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Affiliation(s)
- Cezary Czaplewski
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Agnieszka Karczyńska
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Adam K Sieradzan
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Adam Liwo
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
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Dutagaci B, Heo L, Feig M. Structure refinement of membrane proteins via molecular dynamics simulations. Proteins 2018; 86:738-750. [PMID: 29675899 PMCID: PMC6013386 DOI: 10.1002/prot.25508] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 04/09/2018] [Accepted: 04/14/2018] [Indexed: 12/12/2022]
Abstract
A refinement protocol based on physics-based techniques established for water soluble proteins is tested for membrane protein structures. Initial structures were generated by homology modeling and sampled via molecular dynamics simulations in explicit lipid bilayer and aqueous solvent systems. Snapshots from the simulations were selected based on scoring with either knowledge-based or implicit membrane-based scoring functions and averaged to obtain refined models. The protocol resulted in consistent and significant refinement of the membrane protein structures similar to the performance of refinement methods for soluble proteins. Refinement success was similar between sampling in the presence of lipid bilayers and aqueous solvent but the presence of lipid bilayers may benefit the improvement of lipid-facing residues. Scoring with knowledge-based functions (DFIRE and RWplus) was found to be as good as scoring using implicit membrane-based scoring functions suggesting that differences in internal packing is more important than orientations relative to the membrane during the refinement of membrane protein homology models.
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Affiliation(s)
- Bercem Dutagaci
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - Lim Heo
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - Michael Feig
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
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