1
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Pala D, Clark DE. Caught between a ROCK and a hard place: current challenges in structure-based drug design. Drug Discov Today 2024; 29:104106. [PMID: 39029868 DOI: 10.1016/j.drudis.2024.104106] [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: 04/11/2024] [Revised: 06/27/2024] [Accepted: 07/13/2024] [Indexed: 07/21/2024]
Abstract
The discipline of structure-based drug design (SBDD) is several decades old and it is tempting to think that the proliferation of experimental structures for many drug targets might make computer-aided drug design (CADD) straightforward. However, this is far from true. In this review, we illustrate some of the challenges that CADD scientists face every day in their work, even now. We use Rho-associated protein kinase (ROCK), and public domain structures and data, as an example to illustrate some of the challenges we have experienced during our project targeting this protein. We hope that this will help to prevent unrealistic expectations of what CADD can accomplish and to educate non-CADD scientists regarding the challenges still facing their CADD colleagues.
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Affiliation(s)
- Daniele Pala
- Medicinal Chemistry and Drug Design Technologies Department, Chiesi Farmaceutici S.p.A, Research Center, Largo Belloli 11/a, 43122 Parma, Italy
| | - David E Clark
- Charles River, 6-9 Spire Green Centre, Flex Meadow, Harlow CM19 5TR, UK.
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2
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Mueller NPF, Carloni P, Alfonso-Prieto M. Molecular determinants of acrylamide neurotoxicity through covalent docking. Front Pharmacol 2023; 14:1125871. [PMID: 36937867 PMCID: PMC10018202 DOI: 10.3389/fphar.2023.1125871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 02/17/2023] [Indexed: 03/06/2023] Open
Abstract
Acrylamide (ACR) is formed during food processing by Maillard reaction between sugars and proteins at high temperatures. It is also used in many industries, from water waste treatment to manufacture of paper, fabrics, dyes and cosmetics. Unfortunately, cumulative exposure to acrylamide, either from diet or at the workplace, may result in neurotoxicity. Such adverse effects arise from covalent adducts formed between acrylamide and cysteine residues of several neuronal proteins via a Michael addition reaction. The molecular determinants of acrylamide reactivity and its impact on protein function are not completely understood. Here we have compiled a list of acrylamide protein targets reported so far in the literature in connection with neurotoxicity and performed a systematic covalent docking study. Our results indicate that acrylamide binding to cysteine is favored in the presence of nearby positively charged amino acids, such as lysines and arginines. For proteins with more than one reactive Cys, docking scores were able to discriminate between the primary ACR modification site and secondary sites modified only at high ACR concentrations. Therefore, docking scores emerge as a potential filter to predict Cys reactivity against acrylamide. Inspection of the ACR-protein complex structures provides insights into the putative functional consequences of ACR modification, especially for non-enzyme proteins. Based on our study, covalent docking is a promising computational tool to predict other potential protein targets mediating acrylamide neurotoxicity.
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Affiliation(s)
- Nicolas Pierre Friedrich Mueller
- Institute for Advanced Simulations IAS-5, Institute of Neuroscience and Medicine INM-9, Computational Biomedicine, Forschungszentrum Jülich, Jülich, Germany
- Faculty of Mathematics and Natural Sciences, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Paolo Carloni
- Institute for Advanced Simulations IAS-5, Institute of Neuroscience and Medicine INM-9, Computational Biomedicine, Forschungszentrum Jülich, Jülich, Germany
- Department of Physics, RWTH Aachen University, Aachen, Germany
| | - Mercedes Alfonso-Prieto
- Institute for Advanced Simulations IAS-5, Institute of Neuroscience and Medicine INM-9, Computational Biomedicine, Forschungszentrum Jülich, Jülich, Germany
- Cécile and Oskar Vogt Institute for Brain Research, Medical Faculty, University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- *Correspondence: Mercedes Alfonso-Prieto,
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3
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Zhu W, Butrin A, Melani RD, Doubleday PF, Ferreira GM, Tavares MT, Habeeb Mohammad TS, Beaupre BA, Kelleher NL, Moran GR, Liu D, Silverman RB. Rational Design, Synthesis, and Mechanism of (3 S,4 R)-3-Amino-4-(difluoromethyl)cyclopent-1-ene-1-carboxylic Acid: Employing a Second-Deprotonation Strategy for Selectivity of Human Ornithine Aminotransferase over GABA Aminotransferase. J Am Chem Soc 2022; 144:5629-5642. [PMID: 35293728 PMCID: PMC9181902 DOI: 10.1021/jacs.2c00924] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Human ornithine aminotransferase (hOAT) is a pyridoxal 5'-phosphate (PLP)-dependent enzyme that contains a similar active site to that of γ-aminobutyric acid aminotransferase (GABA-AT). Recently, pharmacological inhibition of hOAT was recognized as a potential therapeutic approach for hepatocellular carcinoma. In this work, we first studied the inactivation mechanisms of hOAT by two well-known GABA-AT inactivators (CPP-115 and OV329). Inspired by the inactivation mechanistic difference between these two aminotransferases, a series of analogues were designed and synthesized, leading to the discovery of analogue 10b as a highly selective and potent hOAT inhibitor. Intact protein mass spectrometry, protein crystallography, and dialysis experiments indicated that 10b was converted to an irreversible tight-binding adduct (34) in the active site of hOAT, as was the unsaturated analogue (11). The comparison of kinetic studies between 10b and 11 suggested that the active intermediate (17b) was only generated in hOAT and not in GABA-AT. Molecular docking studies and pKa computational calculations highlighted the importance of chirality and the endocyclic double bond for inhibitory activity. The turnover mechanism of 10b was supported by mass spectrometric analysis of dissociable products and fluoride ion release experiments. Notably, the stopped-flow experiments were highly consistent with the proposed mechanism, suggesting a relatively slow hydrolysis rate for hOAT. The novel second-deprotonation mechanism of 10b contributes to its high potency and significantly enhanced selectivity for hOAT inhibition.
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Affiliation(s)
- Wei Zhu
- Department of Chemistry, Chemistry of Life Processes Institute, and Center for Developmental Therapeutics, Northwestern University, Evanston, Illinois 60208, United States
| | - Arseniy Butrin
- Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, Illinois 60660, United States
| | - Rafael D Melani
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois 60208, United States
| | - Peter F Doubleday
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois 60208, United States
| | - Glaucio Monteiro Ferreira
- Department of Clinical and Toxicological Analyses, School of Pharmaceutical Sciences, University of São Paulo, São Paulo, SP 05508-000, Brazil
| | - Mauricio T Tavares
- Department of Molecular Medicine, Scripps Research, Jupiter, Florida 33458, United States
| | - Thahani S Habeeb Mohammad
- Department of Chemistry, Chemistry of Life Processes Institute, and Center for Developmental Therapeutics, Northwestern University, Evanston, Illinois 60208, United States
| | - Brett A Beaupre
- Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, Illinois 60660, United States
| | - Neil L Kelleher
- Department of Chemistry, Chemistry of Life Processes Institute, and Center for Developmental Therapeutics, Northwestern University, Evanston, Illinois 60208, United States.,Department of Molecular Biosciences, Northwestern University, Evanston, Illinois 60208, United States
| | - Graham R Moran
- Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, Illinois 60660, United States
| | - Dali Liu
- Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, Illinois 60660, United States
| | - Richard B Silverman
- Department of Chemistry, Chemistry of Life Processes Institute, and Center for Developmental Therapeutics, Northwestern University, Evanston, Illinois 60208, United States.,Department of Molecular Biosciences, Northwestern University, Evanston, Illinois 60208, United States.,Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, United States
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4
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Nimma S, Gu W, Manik MK, Ve T, Nanson JD, Kobe B. Crystal structure of the Toll/interleukin-1 receptor (TIR) domain of IL-1R10 provides structural insights into TIR domain signaling. FEBS Lett 2022; 596:886-897. [PMID: 35038778 DOI: 10.1002/1873-3468.14288] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 12/24/2021] [Accepted: 01/03/2022] [Indexed: 11/09/2022]
Abstract
The Toll/interleukin-1 receptor (TIR) domains are key innate immune signaling modules. Here, we present the crystal structure of the TIR domain of human Interleukin-1 receptor 10 (IL-1R10), also called IL-1RAPL2. It is similar to that of IL-1R9 (IL-1RAPL1) but shows significant structural differences to those from Toll-like receptors (TLRs) and the adaptor proteins MAL and MyD88. Interactions of TIR domains in their respective crystals and the higher-order assemblies (MAL and MyD88) reveal the presence of a common 'BCD surface', suggesting its functional significance. We also show that the TIR domains of IL-1R10 and IL-1R9 lack NADase activity, consistent with their structures. Our study provides a foundation for unraveling the functions of IL-1R9 and IL-1R10.
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Affiliation(s)
- Surekha Nimma
- The University of Queensland, School of Chemistry and Molecular Biosciences, Australian Infectious Diseases Research Centre and Institute of Molecular Bioscience, Brisbane, Queensland, 4072, Australia
| | - Weixi Gu
- The University of Queensland, School of Chemistry and Molecular Biosciences, Australian Infectious Diseases Research Centre and Institute of Molecular Bioscience, Brisbane, Queensland, 4072, Australia
| | - Mohammad K Manik
- The University of Queensland, School of Chemistry and Molecular Biosciences, Australian Infectious Diseases Research Centre and Institute of Molecular Bioscience, Brisbane, Queensland, 4072, Australia
| | - Thomas Ve
- Griffith University, Institute for Glycomics, Southport, Queensland, 4222, Australia
| | - Jeffrey D Nanson
- The University of Queensland, School of Chemistry and Molecular Biosciences, Australian Infectious Diseases Research Centre and Institute of Molecular Bioscience, Brisbane, Queensland, 4072, Australia
| | - Bostjan Kobe
- The University of Queensland, School of Chemistry and Molecular Biosciences, Australian Infectious Diseases Research Centre and Institute of Molecular Bioscience, Brisbane, Queensland, 4072, Australia
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5
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Nakagawa H, Tamada T. Hydration and its Hydrogen Bonding State on a Protein Surface in the Crystalline State as Revealed by Molecular Dynamics Simulation. Front Chem 2021; 9:738077. [PMID: 34733819 PMCID: PMC8558535 DOI: 10.3389/fchem.2021.738077] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 09/29/2021] [Indexed: 11/13/2022] Open
Abstract
Protein hydration is crucial for the stability and molecular recognition of a protein. Water molecules form a hydration water network on a protein surface via hydrogen bonds. This study examined the hydration structure and hydrogen bonding state of a protein, staphylococcal nuclease, at various hydration levels in its crystalline state by all-atom molecular dynamics (MD) simulation. Hydrophilic residues were more hydrated than hydrophobic residues. As the water content increases, both types of residues were uniformly more hydrated. The number of hydrogen bonds per single water asymptotically approaches 4, the same as bulk water. The distances and angles of hydrogen bonds in hydration water in the protein crystal were almost the same as those in the tetrahedral structure of bulk water regardless of the hydration level. The hydrogen bond structure of hydration water observed by MD simulations of the protein crystalline state was compared to the Hydrogen and Hydration Database for Biomolecule from experimental protein crystals.
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Affiliation(s)
- Hiroshi Nakagawa
- Materials Science Research Center, Japan Atomic Energy Agency, Ibaraki, Japan.,J-PARC Center, Japan Atomic Energy Agency, Ibaraki, Japan
| | - Taro Tamada
- Institute for Quantum Life Science, National Institutes for Quantum Science and Technology, Ibaraki, Japan
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6
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Samways ML, Taylor RD, Bruce Macdonald HE, Essex JW. Water molecules at protein-drug interfaces: computational prediction and analysis methods. Chem Soc Rev 2021; 50:9104-9120. [PMID: 34184009 DOI: 10.1039/d0cs00151a] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The fundamental importance of water molecules at drug-protein interfaces is now widely recognised and a significant feature in structure-based drug design. Experimental methods for analysing the role of water in drug binding have many challenges, including the accurate location of bound water molecules in crystal structures, and problems in resolving specific water contributions to binding thermodynamics. Computational analyses of binding site water molecules provide an alternative, and in principle complete, structural and thermodynamic picture, and their use is now commonplace in the pharmaceutical industry. In this review, we describe the computational methodologies that are available and discuss their strengths and weaknesses. Additionally, we provide a critical analysis of the experimental data used to validate the methods, regarding the type and quality of experimental structural data. We also discuss some of the fundamental difficulties of each method and suggest directions for future study.
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Affiliation(s)
- Marley L Samways
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, UK.
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7
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Dimovasili C, Fadouloglou VE, Kefala A, Providaki M, Kotsifaki D, Kanavouras K, Sarrou I, Plaitakis A, Zaganas I, Kokkinidis M. Crystal structure of glutamate dehydrogenase 2, a positively selected novel human enzyme involved in brain biology and cancer pathophysiology. J Neurochem 2021; 157:802-815. [PMID: 33421122 DOI: 10.1111/jnc.15296] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 12/04/2020] [Accepted: 01/06/2021] [Indexed: 01/01/2023]
Abstract
INTRODUCTION Mammalian glutamate dehydrogenase (hGDH1 in human cells) interconverts glutamate to α-ketoglutarate and ammonia while reducing NAD(P) to NAD(P)H. During primate evolution, humans and great apes have acquired hGDH2, an isoenzyme that underwent rapid evolutionary adaptation concomitantly with brain expansion, thereby acquiring unique catalytic and regulatory properties that permitted its function under conditions inhibitory to its ancestor hGDH1. Although the 3D-structures of GDHs, including hGDH1, have been determined, attempts to determine the hGDH2 structure were until recently unsuccessful. Comparison of the hGDH1/hGDH2 structures would enable a detailed understanding of their evolutionary differences. This work aimed at the determination of the hGDH2 crystal structure and the analysis of its functional implications. Recombinant hGDH2 was produced in the Spodoptera frugiperda ovarian cell line Sf21, using the Baculovirus expression system. Purification was achieved via a two-step chromatography procedure. hGDH2 was crystallized, X-ray diffraction data were collected using synchrotron radiation and the structure was determined by molecular replacement. The hGDH2 structure is reported at a resolution of 2.9 Å. The enzyme adopts a novel semi-closed conformation, which is an intermediate between known open and closed GDH1 conformations, differing from both. The structure enabled us to dissect previously reported biochemical findings and to structurally interpret the effects of evolutionary amino acid substitutions, including Arg470His, on ADP affinity. In conclusion, our data provide insights into the structural basis of hGDH2 properties, the functional evolution of hGDH isoenzymes, and open new prospects for drug design, especially for cancer therapeutics.
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Affiliation(s)
- Christina Dimovasili
- Neurology Laboratory, Medical School, University of Crete, Heraklion, Crete, Greece.,Departments of Psychiatry and Neuroscience, Center for Molecular Biology and Genetics of Neurodegeneration, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Vasiliki E Fadouloglou
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Crete, Greece.,Department of Molecular Biology and Genetics, Democritus University of Thrace, Alexandroupolis, Greece
| | - Aikaterini Kefala
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Crete, Greece.,Department of Biology, University of Crete, Heraklion, Crete, Greece
| | - Mary Providaki
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Crete, Greece
| | - Dina Kotsifaki
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Crete, Greece
| | - Konstantinos Kanavouras
- Neurology Laboratory, Medical School, University of Crete, Heraklion, Crete, Greece.,Department of Neurology, "G. Gennimatas" General Hospital, Athens, Greece
| | - Iosifina Sarrou
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Crete, Greece.,Center for Free-Electron Laser Science/DESY, Hamburg, Germany
| | - Andreas Plaitakis
- Neurology Laboratory, Medical School, University of Crete, Heraklion, Crete, Greece
| | - Ioannis Zaganas
- Neurology Laboratory, Medical School, University of Crete, Heraklion, Crete, Greece
| | - Michael Kokkinidis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Crete, Greece.,Department of Biology, University of Crete, Heraklion, Crete, Greece
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8
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Zaucha J, Softley CA, Sattler M, Frishman D, Popowicz GM. Deep learning model predicts water interaction sites on the surface of proteins using limited-resolution data. Chem Commun (Camb) 2020; 56:15454-15457. [PMID: 33237041 DOI: 10.1039/d0cc04383d] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We develop a residual deep learning model, hotWater (https://pypi.org/project/hotWater/), to identify key water interaction sites on proteins for binding models and drug discovery. This is tested on new crystal structures, as well as cryo-EM and NMR structures from the PDB and in crystallographic refinement with promising results.
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Affiliation(s)
- Jan Zaucha
- Department of Bioinformatics, Wissenschaftszentrum Weihenstephan, Technische Universität München, Maximus-von-Imhof-Forum 3, 85354 Freising, Germany.
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9
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Mobility of water and of protein atoms at the protein-water interface, monitored by anisotropic atomic displacement parameters, are largely uncorrelated. Amino Acids 2020; 52:435-443. [PMID: 32008094 DOI: 10.1007/s00726-020-02820-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 01/22/2020] [Indexed: 01/03/2023]
Abstract
A non-redundant set of 231 protein crystal structures refined at a resolution better than (or equal to) 1 Å was extracted from the Protein Data Bank and the degree of conformational rigidity at the protein-water interface was examined by means of the Hirshfeld test and by comparing the orientations of the anisotropic Us for contacting protein and water atoms. Contacts between protein and water atoms are more rigid that contacts between water atoms and the degree of rigidity increases for shorter contacts and for more hydrogen-bonded atoms. Nevertheless, water and protein atoms are not rigidly held together. On the contrary, they seem to have little influence on their mobility to such an extent that hydration water, different from the protein atoms, cannot be considered to be properly in the solid state.
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10
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Maurer M, Oostenbrink C. Water in protein hydration and ligand recognition. J Mol Recognit 2019; 32:e2810. [PMID: 31456282 PMCID: PMC6899928 DOI: 10.1002/jmr.2810] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 07/31/2019] [Accepted: 08/01/2019] [Indexed: 12/16/2022]
Abstract
This review describes selected basics of water in biomolecular recognition. We focus on a qualitative understanding of the most important physical aspects, how these change in magnitude between bulk water and protein environment, and how the roles that water plays for proteins arise from them. These roles include mechanical support, thermal coupling, dielectric screening, mass and charge transport, and the competition with a ligand for the occupation of a binding site. The presence or absence of water has ramifications that range from the thermodynamic binding signature of a single ligand up to cellular survival. The large inhomogeneity in water density, polarity and mobility around a solute is hard to assess in experiment. This is a source of many difficulties in the solvation of protein models and computational studies that attempt to elucidate or predict ligand recognition. The influence of water in a protein binding site on the experimental enthalpic and entropic signature of ligand binding is still a point of much debate. The strong water‐water interaction in enthalpic terms is counteracted by a water molecule's high mobility in entropic terms. The complete arrest of a water molecule's mobility sets a limit on the entropic contribution of a water displacement process, while the solvent environment sets limits on ligand reactivity.
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Affiliation(s)
- Manuela Maurer
- Institute of Molecular Modeling and Simulation, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Chris Oostenbrink
- Institute of Molecular Modeling and Simulation, University of Natural Resources and Life Sciences, Vienna, Austria
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11
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Jones L, Tynes M, Smith P. Prediction of models for ordered solvent in macromolecular structures by a classifier based upon resolution-independent projections of local feature data. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2019; 75:696-717. [PMID: 31373570 PMCID: PMC6677017 DOI: 10.1107/s2059798319008933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 06/22/2019] [Indexed: 11/11/2022]
Abstract
Current software tools for the automated building of models for macromolecular X-ray crystal structures are capable of assembling high-quality models for ordered macromolecule and small-molecule scattering components with minimal or no user supervision. Many of these tools also incorporate robust functionality for modelling the ordered water molecules that are found in nearly all macromolecular crystal structures. However, no current tools focus on differentiating these ubiquitous water molecules from other frequently occurring multi-atom solvent species, such as sulfate, or the automated building of models for such species. PeakProbe has been developed specifically to address the need for such a tool. PeakProbe predicts likely solvent models for a given point (termed a `peak') in a structure based on analysis (`probing') of its local electron density and chemical environment. PeakProbe maps a total of 19 resolution-dependent features associated with electron density and two associated with the local chemical environment to a two-dimensional score space that is independent of resolution. Peaks are classified based on the relative frequencies with which four different classes of solvent (including water) are observed within a given region of this score space as determined by large-scale sampling of solvent models in the Protein Data Bank. Designed to classify peaks generated from difference density maxima, PeakProbe also incorporates functionality for identifying peaks associated with model errors or clusters of peaks likely to correspond to multi-atom solvent, and for the validation of existing solvent models using solvent-omit electron-density maps. When tasked with classifying peaks into one of four distinct solvent classes, PeakProbe achieves greater than 99% accuracy for both peaks derived directly from the atomic coordinates of existing solvent models and those based on difference density maxima. While the program is still under development, a fully functional version is publicly available. PeakProbe makes extensive use of cctbx libraries, and requires a PHENIX licence and an up-to-date phenix.python environment for execution.
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Affiliation(s)
- Laurel Jones
- Department of Chemistry, Fordham University, Bronx, NY 10458, USA
| | - Michael Tynes
- Department of Computer and Information Science, Fordham University, Bronx, NY 10458, USA
| | - Paul Smith
- Department of Chemistry, Fordham University, Bronx, NY 10458, USA
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12
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Carugo O. Anisotropic waters in atomic resolution protein crystal structures. Int J Biol Macromol 2019; 135:940-944. [PMID: 31170487 DOI: 10.1016/j.ijbiomac.2019.06.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 05/31/2019] [Accepted: 06/02/2019] [Indexed: 12/20/2022]
Abstract
In protein crystal structures at extremely high resolution, B-factors of water oxygen atoms can be refined anisotropically. Here, some properties and trends associated with the anisotropy of the water oxygen B-factors are presented and commented. Anisotropy, defined as the ratio of the highest and the smallest eigenvalue of the anisotropic B-factor, is very variable and its distribution can be described by a Gumpel function, which slightly depends on the equivalent isotropic B-factor. Moreover, water oxygen atom anisotropies are very similar in the first and in the second hydration layers; are nearly independent of the number of hydrogen bonds that are formed by the water molecule; and are weekly correlated with protein atom anisotropy. This suggests that hydration water molecules might be in a physicochemical state intermediate between the liquid state, which is present and abundant in the crystal, and the solid state, which is assumed by protein. Further studies and analyses are apparently necessary to investigate this hypothesis.
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Affiliation(s)
- Oliviero Carugo
- Department of Chemistry, University of Pavia, Pavia, Italy; Department of Structural and Computational Biology, University of Vienna, Vienna, Austria.
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