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Okada T, Tomoike F. Distance-based global analysis of consistent cis-bonds in protein backbones. Heliyon 2023; 9:e18598. [PMID: 37576297 PMCID: PMC10413078 DOI: 10.1016/j.heliyon.2023.e18598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 07/13/2023] [Accepted: 07/21/2023] [Indexed: 08/15/2023] Open
Abstract
Biological polypeptides are known to contain cis-linkage in their main chain as a minor but important feature. Such anomalous connection of amino acids has different structural and functional effects on proteins. Experimental evidence of cis-bonds in proteins is mainly obtained using X-ray crystallography and other methods in the field of structural biology. To date, extensive analyses have been carried out on the experimentally found cis-bonds using the Protein Data Bank (PDB) entry-wise or residue-wise; however, their consistency in each protein has not been examined on a global scale. Data accumulation and advances in computational methodology enable the use of new approaches from a proteomic point of view. Here, we sought to carry out protein-wise analysis and describe a simple procedure for the detection and confirmation of cis-bonds from a set of experimental PDB chains for a protein to discriminate this type of bond from isomerizable and/or misassigned bonds. The resulting set of consistent cis bonds (found at identical positions in multiple chains) provides unprecedented insights into the trend of "high cis content" proteins and the upper limit of consistent cis bonds per polypeptide length. Recognizing such limit would not only be important for a practical check of upcoming structures, but also for the design of novel protein folds beyond the evolutionally-acquired repertoire.
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Affiliation(s)
- Tetsuji Okada
- Department of Life Science, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo, 171-8588, Japan
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2
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Wych DC, Aoto PC, Vu L, Wolff AM, Mobley DL, Fraser JS, Taylor SS, Wall ME. Molecular-dynamics simulation methods for macromolecular crystallography. Acta Crystallogr D Struct Biol 2023; 79:50-65. [PMID: 36601807 PMCID: PMC9815100 DOI: 10.1107/s2059798322011871] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 12/13/2022] [Indexed: 12/31/2022] Open
Abstract
It is investigated whether molecular-dynamics (MD) simulations can be used to enhance macromolecular crystallography (MX) studies. Historically, protein crystal structures have been described using a single set of atomic coordinates. Because conformational variation is important for protein function, researchers now often build models that contain multiple structures. Methods for building such models can fail, however, in regions where the crystallographic density is difficult to interpret, for example at the protein-solvent interface. To address this limitation, a set of MD-MX methods that combine MD simulations of protein crystals with conventional modeling and refinement tools have been developed. In an application to a cyclic adenosine monophosphate-dependent protein kinase at room temperature, the procedure improved the interpretation of ambiguous density, yielding an alternative water model and a revised protein model including multiple conformations. The revised model provides mechanistic insights into the catalytic and regulatory interactions of the enzyme. The same methods may be used in other MX studies to seek mechanistic insights.
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Affiliation(s)
- David C. Wych
- Computer, Computational and Statistical Sciences Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
- Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
- Department of Pharmaceutical Sciences, University of California, Irvine, Irvine, CA 92697, USA
| | - Phillip C. Aoto
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Lily Vu
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Alexander M. Wolff
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94158, USA
| | - David L. Mobley
- Department of Pharmaceutical Sciences, University of California, Irvine, Irvine, CA 92697, USA
- Department of Chemistry, University of California, Irvine, Irvine, CA 92697, USA
| | - James S. Fraser
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Susan S. Taylor
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
| | - Michael E. Wall
- Computer, Computational and Statistical Sciences Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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3
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Dolenc J, Haywood EJ, Zhu T, Smith LJ. Backbone N-Amination Promotes the Folding of β-Hairpin Peptides via a Network of Hydrogen Bonds. J Chem Inf Model 2022; 62:6704-6714. [PMID: 35816656 PMCID: PMC9795546 DOI: 10.1021/acs.jcim.2c00516] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Molecular dynamics (MD) simulations have been used to characterize the effects of backbone N-amination of residues in a model β-hairpin peptide. This modification is of considerable interest as N-aminated peptides have been shown to inhibit amyloid-type aggregation. Six derivatives of the β-hairpin peptide, which contain one, two, or four N-aminated residues, have been studied. For each peptide 100 ns MD simulations starting from the folded β-hairpin structure were performed. The effects of the N-amination prove to be very sequence dependent. N-Amination of a residue involved in interstrand hydrogen bonding (Val3) leads to unfolding of the β-hairpin, whereas N-amination of a residue toward the C-terminus (Leu11) gives fraying at the termini of the peptide. In the other derivatives the peptide remains folded, with increasing levels of N-amination reducing the right-handed twist of the β-hairpin and favoring population of a type II' rather than a type I' β-turn. MD simulations (100 ns) have also been run for each peptide starting from an unfolded extended chain. Here, the peptide with four N-aminated residues shows the most folding into the β-hairpin (34%). Analysis of the simulations shows that N-amination favors the population of β (φ, ψ) conformations by the preceding residue due to, at least in part, a network of weak NH2(i)-CO(i) and NH2(i)-CO(i-2) hydrogen bonds. It also leads to a reduction of misfolding because of changes in the hydrogen-bonding potential. Both of these features help funnel the peptide to the folded β-hairpin structure. The conformational insights provided through this work give a firm foundation for the design of N-aminated peptide inhibitors for modulating protein-protein interactions and aggregation.
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Affiliation(s)
- Jožica Dolenc
- Chemistry
- Biology
- Pharmacy Information Center, ETH Zurich, Zurich CH-8093, Switzerland
| | - Esme J. Haywood
- Inorganic
Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Tingting Zhu
- Inorganic
Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Lorna J. Smith
- Inorganic
Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom, (L.J.S.)
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4
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Thorn A. Artificial intelligence in the experimental determination and prediction of macromolecular structures. Curr Opin Struct Biol 2022; 74:102368. [DOI: 10.1016/j.sbi.2022.102368] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 02/22/2022] [Accepted: 03/08/2022] [Indexed: 11/26/2022]
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5
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Hayward S, Milner-White EJ. Determination of amino acids that favour the α L region using Ramachandran propensity plots. Implications for α-sheet as the possible amyloid intermediate. J Struct Biol 2021; 213:107738. [PMID: 33838226 DOI: 10.1016/j.jsb.2021.107738] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 04/01/2021] [Accepted: 04/04/2021] [Indexed: 11/28/2022]
Abstract
In amyloid diseases an insoluble amyloid fibril forms via a soluble oligomeric intermediate. It is this intermediate that mediates toxicity and it has been suggested, somewhat controversially, that it has the α-sheet structure. Nests and α-strands are similar peptide motifs in that alternate residues lie in the αR and γL regions of the Ramachandran plot for nests, or αR and αL regions for α-strands. In nests a concavity is formed by the main chain NH atoms whereas in α-strands the main chain is almost straight. Using "Ramachandran propensity plots" to focus on the αL/γL region, it is shown that glycine favours γL (82% of amino acids are glycine), but disfavours αL (3% are glycine). Most charged and polar amino acids favour αL with asparagine having by far the highest propensity. Thus, glycine favours nests but, contrary to common expectation, should not favour α-sheet. By contrast most charged or polar amino acids should favour α-sheet by their propensity for the αL conformation, which is more discriminating amongst amino acids than the αR conformation. Thus, these results suggest the composition of sequences that favour α-sheet formation and point towards effective prediction of α-sheet from sequence.
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Affiliation(s)
- Steven Hayward
- Computational Biology Laboratory, School of Computing Sciences, University of East Anglia, Norwich NR4 7TJ, UK.
| | - E James Milner-White
- College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
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6
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Bastida A, Carmona-García J, Zúñiga J, Requena A, Cerezo J. Intraresidual Correlated Motions in Peptide Chains. J Chem Inf Model 2019; 59:4524-4527. [PMID: 31670959 DOI: 10.1021/acs.jcim.9b00842] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We investigate the interresidual and intraresidual correlations between dihedral displacements of adjacent residues within model polyalanine peptides by analyzing extensive molecular dynamics trajectories. Correlations are evaluated individually at different residue conformations covering the whole (ϕi,ψi)-space. From these, we draw maps that unveil an unprecedented strong intramolecular correlation displaying opposite (correlated/anticorrelated) behaviors at different conformations. Both interresidual and intraresidual correlations arise from the propensity of the peptide to minimize the overall atomic displacements.
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Affiliation(s)
- Adolfo Bastida
- Departamento de Química Física , Universidad de Murcia , 30100 Murcia , Spain
| | | | - José Zúñiga
- Departamento de Química Física , Universidad de Murcia , 30100 Murcia , Spain
| | - Alberto Requena
- Departamento de Química Física , Universidad de Murcia , 30100 Murcia , Spain
| | - Javier Cerezo
- Departamento de Química , Universidad Autónoma de Madrid , 28049 Madrid , Spain
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Banchenko S, Arumughan A, Petrović S, Schwefel D, Wanker EE, Roske Y, Heinemann U. Common Mode of Remodeling AAA ATPases p97/CDC48 by Their Disassembling Cofactors ASPL/PUX1. Structure 2019; 27:1830-1841.e3. [PMID: 31648844 DOI: 10.1016/j.str.2019.10.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 08/16/2019] [Accepted: 09/30/2019] [Indexed: 10/25/2022]
Abstract
The hexameric ring structure of the type II AAA+ ATPases is considered as stable and permanent. Recently, the UBX domain-containing cofactors Arabidopsis thaliana PUX1 and human alveolar soft part sarcoma locus (ASPL) were reported to bind and disassemble the cognate AAA+ ATPases AtCDC48 and human p97. Here, we present two crystal structures related to these complexes: a truncated AtCDC48 (AtCDC48-ND1) and a hybrid complex containing human p97-ND1 and the UBX domain of plant PUX1 (p97-ND1:PUX1-UBX). These structures reveal close similarity between the human and plant AAA+ ATPases, but also highlight differences between disassembling and non-disassembling AAA+ ATPase cofactors. Based on an AtCDC48 disassembly assay with PUX1 and known crystal structures of the p97-bound human cofactor ASPL, we propose a general ATPase disassembly model. Thus, our structural and biophysical investigations provide detailed insight into the mechanism of AAA+ ATPase disassembly by UBX domain cofactors and suggest a general mode of regulating the cellular activity of these molecular machines.
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Affiliation(s)
- Sofia Banchenko
- Max-Delbrück-Centrum für Molekulare Medizin, 13125 Berlin, Germany; Institut für Chemie und Biochemie, Freie Universität Berlin, 14195 Berlin, Germany
| | - Anup Arumughan
- Max-Delbrück-Centrum für Molekulare Medizin, 13125 Berlin, Germany; Institut für Chemie und Biochemie, Freie Universität Berlin, 14195 Berlin, Germany
| | - Saša Petrović
- Max-Delbrück-Centrum für Molekulare Medizin, 13125 Berlin, Germany; Institut für Chemie und Biochemie, Freie Universität Berlin, 14195 Berlin, Germany
| | - David Schwefel
- Charité Universitätsmedizin Berlin, 10117 Berlin, Germany
| | - Erich E Wanker
- Max-Delbrück-Centrum für Molekulare Medizin, 13125 Berlin, Germany
| | - Yvette Roske
- Max-Delbrück-Centrum für Molekulare Medizin, 13125 Berlin, Germany.
| | - Udo Heinemann
- Max-Delbrück-Centrum für Molekulare Medizin, 13125 Berlin, Germany; Institut für Chemie und Biochemie, Freie Universität Berlin, 14195 Berlin, Germany.
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8
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Dickman R, Mitchell SA, Figueiredo AM, Hansen DF, Tabor AB. Molecular Recognition of Lipid II by Lantibiotics: Synthesis and Conformational Studies of Analogues of Nisin and Mutacin Rings A and B. J Org Chem 2019; 84:11493-11512. [PMID: 31464129 PMCID: PMC6759747 DOI: 10.1021/acs.joc.9b01253] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Indexed: 12/12/2022]
Abstract
In response to the growing threat posed by antibiotic-resistant bacterial strains, extensive research is currently focused on developing antimicrobial agents that target lipid II, a vital precursor in the biosynthesis of bacterial cell walls. The lantibiotic nisin and related peptides display unique and highly selective binding to lipid II. A key feature of the nisin-lipid II interaction is the formation of a cage-like complex between the pyrophosphate moiety of lipid II and the two thioether-bridged rings, rings A and B, at the N-terminus of nisin. To understand the important structural factors underlying this highly selective molecular recognition, we have used solid-phase peptide synthesis to prepare individual ring A and B structures from nisin, the related lantibiotic mutacin, and synthetic analogues. Through NMR studies of these rings, we have demonstrated that ring A is preorganized to adopt the correct conformation for binding lipid II in solution and that individual amino acid substitutions in ring A have little effect on the conformation. We have also analyzed the turn structures adopted by these thioether-bridged peptides and show that they do not adopt the tight α-turn or β-turn structures typically found in proteins.
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Affiliation(s)
- Rachael Dickman
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.
| | - Serena A. Mitchell
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.
| | - Angelo M. Figueiredo
- Institute
of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, U.K.
| | - D. Flemming Hansen
- Institute
of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, U.K.
| | - Alethea B. Tabor
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.
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9
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Abstract
Protein kinases play important roles in signaling pathways and are widely studied as drug targets. Their active site exhibits remarkable structural variation as observed in the large number of available crystal structures. We have developed a clustering scheme and nomenclature to categorize and label all the observed conformations in human protein kinases. This has enabled us to clearly define the geometry of the active state and to distinguish closely related inactive states which were previously not characterized. Our classification of kinase conformations will help in better understanding the conformational dynamics of these proteins and the development of inhibitors against them. Targeting protein kinases is an important strategy for intervention in cancer. Inhibitors are directed at the active conformation or a variety of inactive conformations. While attempts have been made to classify these conformations, a structurally rigorous catalog of states has not been achieved. The kinase activation loop is crucial for catalysis and begins with the conserved DFGmotif. This motif is observed in two major classes of conformations, DFGin—a set of active and inactive conformations where the Phe residue is in contact with the C-helix of the N-terminal lobe—and DFGout—an inactive form where Phe occupies the ATP site exposing the C-helix pocket. We have developed a clustering of kinase conformations based on the location of the Phe side chain (DFGin, DFGout, and DFGinter or intermediate) and the backbone dihedral angles of the sequence X-D-F, where X is the residue before the DFGmotif, and the DFG-Phe side-chain rotamer, utilizing a density-based clustering algorithm. We have identified eight distinct conformations and labeled them based on the Ramachandran regions (A, alpha; B, beta; L, left) of the XDF motif and the Phe rotamer (minus, plus, trans). Our clustering divides the DFGin group into six clusters including BLAminus, which contains active structures, and two common inactive forms, BLBplus and ABAminus. DFGout structures are predominantly in the BBAminus conformation, which is essentially required for binding type II inhibitors. The inactive conformations have specific features that make them unable to bind ATP, magnesium, and/or substrates. Our structurally intuitive nomenclature will aid in understanding the conformational dynamics of kinases and structure-based development of kinase drugs.
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10
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Iliev S, Gocheva G, Ivanova N, Atanasova B, Petrova J, Madjarova G, Ivanova A. Identification and computational characterization of isomers with cis and trans amide bonds in folate and its analogues. Phys Chem Chem Phys 2018; 20:28818-28831. [PMID: 30418443 DOI: 10.1039/c8cp04304c] [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
Folate and its synthetic analogues, called antifolates, are known to have diverse bio-applications, for example as cell proliferation stimulators or anticancer drugs. Their molecular structure is important for performing the required biological activity. Since all folate-derived ligands contain a peptide-like amide bond, its configuration is one of the key components for the functional fitness of such compounds. During the modelling of folate and three of its derivatives - methotrexate, 5-methyl tetrahydrofolate, and pteroyl ornithine, we registered significant population of the cis isomers along the amide bond. The properties of the cis and trans forms of the ligands in saline are studied in detail by classical atomistic molecular dynamics and by quantum chemical methods. The calculations predict high probability for coexistence of the cis isomers for two of the ligands. The energetic instability of the cis form is explained with a σ-character admixture into the C[double bond, length as m-dash]O(π) bond, while its magnitude is attributed to the pattern of local electron density redistribution. The cis forms of all molecules have markedly slower structural dynamics than the trans ones, which might affect their behavior in vivo.
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Affiliation(s)
- Stoyan Iliev
- Laboratory of Quantum and Computational Chemistry, Faculty of Chemistry and Pharmacy, University of Sofia, 1 James Bourchier blvd., 1164 Sofia, Bulgaria.
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11
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Croll TI. ISOLDE: a physically realistic environment for model building into low-resolution electron-density maps. Acta Crystallogr D Struct Biol 2018; 74:519-530. [PMID: 29872003 PMCID: PMC6096486 DOI: 10.1107/s2059798318002425] [Citation(s) in RCA: 812] [Impact Index Per Article: 135.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2017] [Accepted: 02/09/2018] [Indexed: 01/19/2023] Open
Abstract
This paper introduces ISOLDE, a new software package designed to provide an intuitive environment for high-fidelity interactive remodelling/refinement of macromolecular models into electron-density maps. ISOLDE combines interactive molecular-dynamics flexible fitting with modern molecular-graphics visualization and established structural biology libraries to provide an immersive interface wherein the model constantly acts to maintain physically realistic conformations as the user interacts with it by directly tugging atoms with a mouse or haptic interface or applying/removing restraints. In addition, common validation tasks are accelerated and visualized in real time. Using the recently described 3.8 Å resolution cryo-EM structure of the eukaryotic minichromosome maintenance (MCM) helicase complex as a case study, it is demonstrated how ISOLDE can be used alongside other modern refinement tools to avoid common pitfalls of low-resolution modelling and improve the quality of the final model. A detailed analysis of changes between the initial and final model provides a somewhat sobering insight into the dangers of relying on a small number of validation metrics to judge the quality of a low-resolution model.
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Affiliation(s)
- Tristan Ian Croll
- Cambridge Institute for Medical Research, University of Cambridge, Wellcome Trust/MRC Building, Cambridge CB2 0XY, England
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12
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Yang Y, Gao J, Wang J, Heffernan R, Hanson J, Paliwal K, Zhou Y. Sixty-five years of the long march in protein secondary structure prediction: the final stretch? Brief Bioinform 2018; 19:482-494. [PMID: 28040746 PMCID: PMC5952956 DOI: 10.1093/bib/bbw129] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 11/15/2016] [Indexed: 11/13/2022] Open
Abstract
Protein secondary structure prediction began in 1951 when Pauling and Corey predicted helical and sheet conformations for protein polypeptide backbone even before the first protein structure was determined. Sixty-five years later, powerful new methods breathe new life into this field. The highest three-state accuracy without relying on structure templates is now at 82-84%, a number unthinkable just a few years ago. These improvements came from increasingly larger databases of protein sequences and structures for training, the use of template secondary structure information and more powerful deep learning techniques. As we are approaching to the theoretical limit of three-state prediction (88-90%), alternative to secondary structure prediction (prediction of backbone torsion angles and Cα-atom-based angles and torsion angles) not only has more room for further improvement but also allows direct prediction of three-dimensional fragment structures with constantly improved accuracy. About 20% of all 40-residue fragments in a database of 1199 non-redundant proteins have <6 Å root-mean-squared distance from the native conformations by SPIDER2. More powerful deep learning methods with improved capability of capturing long-range interactions begin to emerge as the next generation of techniques for secondary structure prediction. The time has come to finish off the final stretch of the long march towards protein secondary structure prediction.
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Affiliation(s)
- Yuedong Yang
- Insitute for Glycomics and School of Information and Communication Technology, Griffith University, Parklands Drive, Southport, QLD, Australia
| | - Jianzhao Gao
- School of Mathematical Sciences and LPMC, Nankai University, Tianjin, China
| | - Jihua Wang
- Shandong Provincial Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou, China
| | - Rhys Heffernan
- Signal Processing Laboratory, Griffith University, Brisbane, Australia
| | - Jack Hanson
- Signal Processing Laboratory, Griffith University, Brisbane, Australia
| | - Kuldip Paliwal
- Signal Processing Laboratory, Griffith University, Brisbane, Australia
| | - Yaoqi Zhou
- Insitute for Glycomics and School of Information and Communication Technology, Griffith University, Parklands Drive, Southport, QLD, Australia
- Shandong Provincial Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou, China
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13
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Delbart F, Brams M, Gruss F, Noppen S, Peigneur S, Boland S, Chaltin P, Brandao-Neto J, von Delft F, Touw WG, Joosten RP, Liekens S, Tytgat J, Ulens C. An allosteric binding site of the α7 nicotinic acetylcholine receptor revealed in a humanized acetylcholine-binding protein. J Biol Chem 2017; 293:2534-2545. [PMID: 29237730 PMCID: PMC5818190 DOI: 10.1074/jbc.m117.815316] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 10/24/2017] [Indexed: 11/06/2022] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) belong to the family of pentameric ligand-gated ion channels and mediate fast excitatory transmission in the central and peripheral nervous systems. Among the different existing receptor subtypes, the homomeric α7 nAChR has attracted considerable attention because of its possible implication in several neurological and psychiatric disorders, including cognitive decline associated with Alzheimer's disease or schizophrenia. Allosteric modulators of ligand-gated ion channels are of particular interest as therapeutic agents, as they modulate receptor activity without affecting normal fluctuations of synaptic neurotransmitter release. Here, we used X-ray crystallography and surface plasmon resonance spectroscopy of α7-acetylcholine-binding protein (AChBP), a humanized chimera of a snail AChBP, which has 71% sequence similarity with the extracellular ligand-binding domain of the human α7 nAChR, to investigate the structural determinants of allosteric modulation. We extended previous observations that an allosteric site located in the vestibule of the receptor offers an attractive target for receptor modulation. We introduced seven additional humanizing mutations in the vestibule-located binding site of AChBP to improve its suitability as a model for studying allosteric binding. Using a fragment-based screening approach, we uncovered an allosteric binding site located near the β8-β9 loop, which critically contributes to coupling ligand binding to channel opening in human α7 nAChR. This work expands our understanding of the topology of allosteric binding sites in AChBP and, by extrapolation, in the human α7 nAChR as determined by electrophysiology measurements. Our insights pave the way for drug design strategies targeting nAChRs involved in ion channel-mediated disorders.
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Affiliation(s)
- Florian Delbart
- From the Department of Cellular and Molecular Medicine, Laboratory of Structural Neurobiology, Faculty of Medicine, KU Leuven, 3000 Leuven, Belgium
| | - Marijke Brams
- From the Department of Cellular and Molecular Medicine, Laboratory of Structural Neurobiology, Faculty of Medicine, KU Leuven, 3000 Leuven, Belgium
| | - Fabian Gruss
- From the Department of Cellular and Molecular Medicine, Laboratory of Structural Neurobiology, Faculty of Medicine, KU Leuven, 3000 Leuven, Belgium
| | - Sam Noppen
- the Department of Microbiology and Immunology, Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, KU Leuven, 3000 Leuven, Belgium
| | - Steve Peigneur
- the Laboratory of Toxicology and Pharmacology, Faculty of Pharmaceutical Sciences, KU Leuven, 3000 Leuven, Belgium
| | - Sandro Boland
- the Center for Innovation and Stimulation of Drug Discovery Leuven, Cistim Leuven vzw, 3001 Heverlee, Belgium
| | - Patrick Chaltin
- the Center for Innovation and Stimulation of Drug Discovery Leuven, Cistim Leuven vzw, 3001 Heverlee, Belgium.,the Center for Innovation and Stimulation of Drug Discovery Leuven and Center for Drug Design and Discovery, KU Leuven, 3001 Heverlee, Belgium
| | - Jose Brandao-Neto
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0QX, United Kingdom, and
| | - Frank von Delft
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0QX, United Kingdom, and
| | - Wouter G Touw
- the Division of Biochemistry, Netherlands Cancer Institute, 1066CX Amsterdam, The Netherlands
| | - Robbie P Joosten
- the Division of Biochemistry, Netherlands Cancer Institute, 1066CX Amsterdam, The Netherlands
| | - Sandra Liekens
- the Department of Microbiology and Immunology, Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, KU Leuven, 3000 Leuven, Belgium
| | - Jan Tytgat
- the Laboratory of Toxicology and Pharmacology, Faculty of Pharmaceutical Sciences, KU Leuven, 3000 Leuven, Belgium
| | - Chris Ulens
- From the Department of Cellular and Molecular Medicine, Laboratory of Structural Neurobiology, Faculty of Medicine, KU Leuven, 3000 Leuven, Belgium,
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14
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Abriata LA. Structural database resources for biological macromolecules. Brief Bioinform 2017; 18:659-669. [PMID: 27273290 DOI: 10.1093/bib/bbw049] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Indexed: 12/30/2022] Open
Abstract
This Briefing reviews the widely used, currently active, up-to-date databases derived from the worldwide Protein Data Bank (PDB) to facilitate browsing, finding and exploring its entries. These databases contain visualization and analysis tools tailored to specific kinds of molecules and interactions, often including also complex metrics precomputed by experts or external programs, and connections to sequence and functional annotation databases. Importantly, updates of most of these databases involves steps of curation and error checks based on specific expertise about the subject molecules or interactions, and removal of sequence redundancy, both leading to better data sets for mining studies compared with the full list of raw PDB entries. The article presents the databases in groups such as those aimed to facilitate browsing through PDB entries, their molecules and their general information, those built to link protein structure with sequence and dynamics, those specific for transmembrane proteins, nucleic acids, interactions of biomacromolecules with each other and with small molecules or metal ions, and those concerning specific structural features or specific protein families. A few webservers directly connected to active databases, and a few databases that have been discontinued but would be important to have back, are also briefly commented on. Along the Briefing, sample cases where these databases have been used to aid structural studies or advance our knowledge about biological macromolecules are referenced. A few specific examples are also given where using these databases is easier and more informative than using raw PDB data.
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15
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Abstract
Macromolecular structure is governed by the strict rules of stereochemistry. Several approaches to the validation of the correctness of the interpretation of crystallographic and NMR data that underlie the models deposited in the PDB are utilized in practice. The stereochemical rules applicable to macromolecular structures are discussed in this chapter. Practical, computer-based methods and tools of verification of how well the models adhere to those established structural principles to assure their quality are summarized.
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16
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Abstract
More than two decades of research have enabled dihedral angle predictions at an accuracy that makes them an interesting alternative or supplement to secondary structure prediction that provides detailed local structure information for every residue of a protein. The evolution of dihedral angle prediction methods is closely linked to advancements in machine learning and other relevant technologies. Consequently recent improvements in large-scale training of deep neural networks have led to the best method currently available, which achieves a mean absolute error of 19° for phi, and 30° for psi. This performance opens interesting perspectives for the application of dihedral angle prediction in the comparison, prediction, and design of protein structures.
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Affiliation(s)
- Olav Zimmermann
- Jülich Supercomputing Centre (JSC), Institute for Advanced Simulation (IAS), Forschungszentrum Jülich GmbH, 52425, Jülich, Germany.
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17
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Vermaas JV, Trebesch N, Mayne CG, Thangapandian S, Shekhar M, Mahinthichaichan P, Baylon JL, Jiang T, Wang Y, Muller MP, Shinn E, Zhao Z, Wen PC, Tajkhorshid E. Microscopic Characterization of Membrane Transporter Function by In Silico Modeling and Simulation. Methods Enzymol 2016; 578:373-428. [PMID: 27497175 PMCID: PMC6404235 DOI: 10.1016/bs.mie.2016.05.042] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Membrane transporters mediate one of the most fundamental processes in biology. They are the main gatekeepers controlling active traffic of materials in a highly selective and regulated manner between different cellular compartments demarcated by biological membranes. At the heart of the mechanism of membrane transporters lie protein conformational changes of diverse forms and magnitudes, which closely mediate critical aspects of the transport process, most importantly the coordinated motions of remotely located gating elements and their tight coupling to chemical processes such as binding, unbinding and translocation of transported substrate and cotransported ions, ATP binding and hydrolysis, and other molecular events fueling uphill transport of the cargo. An increasing number of functional studies have established the active participation of lipids and other components of biological membranes in the function of transporters and other membrane proteins, often acting as major signaling and regulating elements. Understanding the mechanistic details of these molecular processes require methods that offer high spatial and temporal resolutions. Computational modeling and simulations technologies empowered by advanced sampling and free energy calculations have reached a sufficiently mature state to become an indispensable component of mechanistic studies of membrane transporters in their natural environment of the membrane. In this article, we provide an overview of a number of major computational protocols and techniques commonly used in membrane transporter modeling and simulation studies. The article also includes practical hints on effective use of these methods, critical perspectives on their strengths and weak points, and examples of their successful applications to membrane transporters, selected from the research performed in our own laboratory.
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Affiliation(s)
- J V Vermaas
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - N Trebesch
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - C G Mayne
- University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - S Thangapandian
- University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - M Shekhar
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - P Mahinthichaichan
- University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - J L Baylon
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - T Jiang
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Y Wang
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - M P Muller
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; College of Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - E Shinn
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Z Zhao
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - P-C Wen
- University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - E Tajkhorshid
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; College of Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, United States.
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18
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Neale C, Pomès R, García AE. Peptide Bond Isomerization in High-Temperature Simulations. J Chem Theory Comput 2016; 12:1989-99. [PMID: 26866899 DOI: 10.1021/acs.jctc.5b01022] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Force fields for molecular simulation are generally optimized to model macromolecules such as proteins at ambient temperature and pressure. Nevertheless, elevated temperatures are frequently used to enhance conformational sampling, either during system setup or as a component of an advanced sampling technique such as temperature replica exchange. Because macromolecular force fields are now put upon to simulate temperatures and time scales that greatly exceed their original design specifications, it is appropriate to re-evaluate whether these force fields are up to the task. Here, we quantify the rates of peptide bond isomerization in high-temperature simulations of three octameric peptides and a small fast-folding protein. We show that peptide octamers with and without proline residues undergo cis/trans isomerization every 1-5 ns at 800 K with three classical atomistic force fields (AMBER99SB-ILDN, CHARMM22/CMAP, and OPLS-AA/L). On the low microsecond time scale, these force fields permit isomerization of nonprolyl peptide bonds at temperatures ≥500 K, and the CHARMM22/CMAP force field permits isomerization of prolyl peptide bonds ≥400 K. Moreover, the OPLS-AA/L force field allows chiral inversion about the Cα atom at 800 K. Finally, we show that temperature replica exchange permits cis peptide bonds developed at 540 K to subsequently migrate back to the 300 K ensemble, where cis peptide bonds are present in 2 ± 1% of the population of Trp-cage TC5b, including up to 4% of its folded state. Further work is required to assess the accuracy of cis/trans isomerization in the current generation of protein force fields.
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Affiliation(s)
- Chris Neale
- Center for NonLinear Studies (CNLS), MS B258, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Régis Pomès
- Molecular Structure and Function, The Hospital for Sick Children , 686 Bay Street, Toronto, Ontario M5G 0A4, Canada.,Department of Biochemistry, University of Toronto , 101 College Street, Toronto, Ontario M5G 1L7, Canada
| | - Angel E García
- Center for NonLinear Studies (CNLS), MS B258, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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19
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Touw WG, Joosten RP, Vriend G. New Biological Insights from Better Structure Models. J Mol Biol 2016; 428:1375-1393. [PMID: 26869101 DOI: 10.1016/j.jmb.2016.02.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 01/04/2016] [Accepted: 02/01/2016] [Indexed: 02/01/2023]
Abstract
Structure validation is a key component of all steps in the structure determination process, from structure building, refinement, deposition, and evaluation all the way to post-deposition optimisation of structures in the Protein Data Bank (PDB) by re-refinement and re-building. Today, many aspects of protein structures are understood better than 10years ago, and combined with improved software and more computing power, the automated PDB_REDO procedure can significantly improve about 85% of all X-ray structures ever deposited in the PDB. We review structure validation, structure improvement, and a series of validation resources and facilities that give access to improved PDB files and to reports on the quality of the original and the improved structures. Post-deposition optimisation generally leads to improved protein structures and a series of examples will illustrate how that, in turn, leads to improved or even novel biological insights.
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Affiliation(s)
- Wouter G Touw
- Centre for Molecular and Biomolecular Informatics, Radboud University Medical Center, Geert Grooteplein-Zuid 26-28, 6525 GA Nijmegen, The Netherlands
| | - Robbie P Joosten
- Department of Biochemistry, Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | - Gert Vriend
- Centre for Molecular and Biomolecular Informatics, Radboud University Medical Center, Geert Grooteplein-Zuid 26-28, 6525 GA Nijmegen, The Netherlands.
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