1
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Davel CM, Bernat T, Wagner JR, Shirts MR. Parameterization of General Organic Polymers within the Open Force Field Framework. J Chem Inf Model 2024; 64:1290-1305. [PMID: 38303159 PMCID: PMC11090695 DOI: 10.1021/acs.jcim.3c01691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2024]
Abstract
Polymer and chemically modified biopolymer systems present unique challenges to traditional molecular simulation preparation workflows. First, typical polymer and biomolecular input formats, such as Protein Data Bank (PDB) files, lack adequate chemical information needed for the parameterization of new chemistries. Second, polymers are typically too large for accurate partial charge generation methods. In this work, we employ direct chemical perception through the Open Force Field toolkit to create a flexible polymer simulation workflow for organic polymers, encompassing everything from biopolymers to soft materials. We propose and test a new input specification for monomer information that can, along with a 3D conformational geometry, parametrize and simulate most soft-material systems within the same workflow used for smaller ligands. The monomer format encompasses a subset of the SMIRKS substructure query language to uniquely identify chemical information and repeating charges in underspecified systems through matching atomic connectivity. This workflow is combined with several different approaches for automatic partial-charge generation for larger systems. As an initial proof of concept, a variety of diverse polymeric systems were parametrized with the Open Force Field toolkit, including functionalized proteins, DNA, homopolymers, cross-linked systems, and sugars. Additionally, shape properties and radial distribution functions were computed from molecular dynamics simulations of poly(ethylene glycol), polyacrylamide, and poly(N-isopropylacrylamide) homopolymers in aqueous solution and compared to previous simulation results in order to demonstrate a start-to-finish workflow for simulation and property prediction. We expect that these tools will greatly expedite the day-to-day computational research of soft-matter simulations and create a robust atomic-scale polymer specification in conjunction with existing polymer structural notations.
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Affiliation(s)
- Connor M Davel
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Timotej Bernat
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Jeffrey R Wagner
- The Open Force Field Initiative, Open Molecular Software Foundation, Davis, California 95616, United States
| | - Michael R Shirts
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
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2
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Xue B, Yang Q, Zhang Q, Wan X, Fang D, Lin X, Sun G, Gobbo G, Cao F, Mathiowetz AM, Burke BJ, Kumpf RA, Rai BK, Wood GPF, Pickard FC, Wang J, Zhang P, Ma J, Jiang YA, Wen S, Hou X, Zou J, Yang M. Development and Comprehensive Benchmark of a High-Quality AMBER-Consistent Small Molecule Force Field with Broad Chemical Space Coverage for Molecular Modeling and Free Energy Calculation. J Chem Theory Comput 2024; 20:799-818. [PMID: 38157475 DOI: 10.1021/acs.jctc.3c00920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
Biomolecular simulations have become an essential tool in contemporary drug discovery, and molecular mechanics force fields (FFs) constitute its cornerstone. Developing a high quality and broad coverage general FF is a significant undertaking that requires substantial expert knowledge and computing resources, which is beyond the scope of general practitioners. Existing FFs originate from only a limited number of groups and organizations, and they either suffer from limited numbers of training sets, lower than desired quality because of oversimplified representations, or are costly for the molecular modeling community to access. To address these issues, in this work, we developed an AMBER-consistent small molecule FF with extensive chemical space coverage, and we provide Open Access parameters for the entire modeling community. To validate our FF, we carried out benchmarks of quantum mechanics (QM)/molecular mechanics conformer comparison and free energy perturbation calculations on several benchmark data sets. Our FF achieves a higher level of performance at reproducing QM energies and geometries than two popular open-source FFs, OpenFF2 and GAFF2. In relative binding free energy calculations for 31 protein-ligand data sets, comprising 1079 pairs of ligands, the new FF achieves an overall root-mean-square error of 1.19 kcal/mol for ΔΔG and 0.92 kcal/mol for ΔG on a subset of 463 ligands without bespoke fitting to the data sets. The results are on par with those of the leading commercial series of OPLS FFs.
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Affiliation(s)
- Bai Xue
- Shenzhen Jingtai Technology Co., Ltd. (XtalPi), Floor 3, Sf Industrial Plant, No. 2 Hongliu Road, Fubao Community, Fubao Street, Futian District, Shenzhen 518045, China
| | - Qingyi Yang
- Medicine Design, Pfizer Inc., 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Qiaochu Zhang
- Shenzhen Jingtai Technology Co., Ltd. (XtalPi), Floor 3, Sf Industrial Plant, No. 2 Hongliu Road, Fubao Community, Fubao Street, Futian District, Shenzhen 518045, China
| | - Xiao Wan
- Shenzhen Jingtai Technology Co., Ltd. (XtalPi), Floor 3, Sf Industrial Plant, No. 2 Hongliu Road, Fubao Community, Fubao Street, Futian District, Shenzhen 518045, China
| | - Dong Fang
- Shenzhen Jingtai Technology Co., Ltd. (XtalPi), Floor 3, Sf Industrial Plant, No. 2 Hongliu Road, Fubao Community, Fubao Street, Futian District, Shenzhen 518045, China
| | - Xiaolu Lin
- Shenzhen Jingtai Technology Co., Ltd. (XtalPi), Floor 3, Sf Industrial Plant, No. 2 Hongliu Road, Fubao Community, Fubao Street, Futian District, Shenzhen 518045, China
| | - Guangxu Sun
- Shenzhen Jingtai Technology Co., Ltd. (XtalPi), Floor 3, Sf Industrial Plant, No. 2 Hongliu Road, Fubao Community, Fubao Street, Futian District, Shenzhen 518045, China
| | - Gianpaolo Gobbo
- XtalPi Inc., 245 Main Street, Cambridge, Massachusetts 02142, United States
| | - Fenglei Cao
- Shenzhen Jingtai Technology Co., Ltd. (XtalPi), Floor 3, Sf Industrial Plant, No. 2 Hongliu Road, Fubao Community, Fubao Street, Futian District, Shenzhen 518045, China
| | - Alan M Mathiowetz
- Medicine Design, Pfizer Inc., 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Benjamin J Burke
- Medicine Design, Pfizer Inc., 10777 Science Center Drive, San Diego, California 92121, United States
| | - Robert A Kumpf
- Medicine Design, Pfizer Inc., 10777 Science Center Drive, San Diego, California 92121, United States
| | - Brajesh K Rai
- Machine Learning and Computational Sciences, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
| | - Geoffrey P F Wood
- Pharmaceutical Science Small Molecule, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Frank C Pickard
- Pharmaceutical Science Small Molecule, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Junmei Wang
- Department of Pharmaceutical Sciences and Computational Chemical Genomics Screening Center, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Peiyu Zhang
- Shenzhen Jingtai Technology Co., Ltd. (XtalPi), Floor 3, Sf Industrial Plant, No. 2 Hongliu Road, Fubao Community, Fubao Street, Futian District, Shenzhen 518045, China
| | - Jian Ma
- Shenzhen Jingtai Technology Co., Ltd. (XtalPi), Floor 3, Sf Industrial Plant, No. 2 Hongliu Road, Fubao Community, Fubao Street, Futian District, Shenzhen 518045, China
| | - Yide Alan Jiang
- XtalPi Inc., 245 Main Street, Cambridge, Massachusetts 02142, United States
| | - Shuhao Wen
- Shenzhen Jingtai Technology Co., Ltd. (XtalPi), Floor 3, Sf Industrial Plant, No. 2 Hongliu Road, Fubao Community, Fubao Street, Futian District, Shenzhen 518045, China
| | - Xinjun Hou
- Medicine Design, Pfizer Inc., 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Junjie Zou
- Shenzhen Jingtai Technology Co., Ltd. (XtalPi), Floor 3, Sf Industrial Plant, No. 2 Hongliu Road, Fubao Community, Fubao Street, Futian District, Shenzhen 518045, China
| | - Mingjun Yang
- Shenzhen Jingtai Technology Co., Ltd. (XtalPi), Floor 3, Sf Industrial Plant, No. 2 Hongliu Road, Fubao Community, Fubao Street, Futian District, Shenzhen 518045, China
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3
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Wang X, Wang Y, Guo M, Wang X, Li Y, Zhang JZH. Assessment of an Electrostatic Energy-Based Charge Model for Modeling the Electrostatic Interactions in Water Solvent. J Chem Theory Comput 2023; 19:6294-6312. [PMID: 37656610 DOI: 10.1021/acs.jctc.3c00467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/03/2023]
Abstract
The protein force field based on the restrained electrostatic potential (RESP) charges has limitations in accurately describing hydrogen bonding interactions in proteins. To address this issue, we propose an alternative approach called the electrostatic energy-based charges (EEC) model, which shows improved performance in describing electrostatic interactions (EIs) of hydrogen bonds in proteins. In this study, we further investigate the performance of the EEC model in modeling EIs in water solvent. Our findings demonstrate that the fixed EEC model can effectively reproduce the quantum mechanics/molecular mechanics (QM/MM)-calculated EIs between a water molecule and various water solvent environments. However, to achieve the same level of computational accuracy, the electrostatic potential (ESP) charge model needs to fluctuate according to the electrostatic environment. Our analysis indicates that the requirement for charge adjustments depends on the specific mathematical and physical representation of EIs as a function of the environment for deriving charges. By comparing with widely used empirical water models calibrated to reproduce experimental properties, we confirm that the performance of the EEC model in reproducing QM/MM EIs is similar to that of general purpose TIP4P-like water models such as TIP4P-Ew and TIP4P/2005. When comparing the computed 10,000 distinct EI values within the range of -40 to 0 kcal/mol with the QM/MM results calculated at the MP2/aug-cc-pVQZ/TIP3P level, we noticed that the mean unsigned error (MUE) for the EEC model is merely 0.487 kcal/mol, which is remarkably similar to the MUE values of the TIP4P-Ew (0.63 kcal/mol) and TIP4P/2005 (0.579 kcal/mol) models. However, both the RESP method and the TIP3P model exhibit a tendency to overestimate the EIs, as evidenced by their higher MUE values of 1.761 and 1.293 kcal/mol, respectively. EEC-based molecular dynamics simulations have demonstrated that, when combined with appropriate van der Waals parameters, the EEC model can closely reproduce oxygen-oxygen radial distribution function and density of water, showing a remarkable similarity to the well-established TIP4P-like empirical water models. Our results demonstrate that the EEC model has the potential to build force fields with comparable accuracy to more sophisticated empirical TIP4P-like water models.
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Affiliation(s)
- Xianwei Wang
- College of Science, Zhejiang University of Technology, Hangzhou, Zhejiang 310023, China
| | - Yiying Wang
- College of Science, Zhejiang University of Technology, Hangzhou, Zhejiang 310023, China
| | - Man Guo
- College of Science, Zhejiang University of Technology, Hangzhou, Zhejiang 310023, China
| | - Xuechao Wang
- College of Science, Zhejiang University of Technology, Hangzhou, Zhejiang 310023, China
| | - Yang Li
- College of Information Science and Engineering, Shandong Agricultural University, Tai'an, Shandong 271018, China
| | - John Z H Zhang
- Shenzhen Institute of Synthetic Biology, Faculty of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong 518055, China
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China
- NYU-ECNU Center for Computational Chemistry at NYU Shanghai, Shanghai 200062, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
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4
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Janitra RS, Destiarani W, Hardianto A, Baroroh U, Rohmatulloh FG, Rustaman, Subroto T, Rukiah, Yusuf M. Multilayer Model of Gold Nanoparticles (AuNPs) and Its Application in the Classical Molecular Dynamics Simulation of Citrate-Capped AuNPs. J Phys Chem B 2023; 127:7103-7110. [PMID: 37540714 DOI: 10.1021/acs.jpcb.3c00771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/06/2023]
Abstract
Studies on the interaction between gold nanoparticles (AuNPs) and functional proteins have been useful in developing diagnostic and therapeutic agents. Such studies require a realistic computational model of AuNPs for successful molecular design works. This study offers a new multilayer model of AuNPs to address the inconsistency between its molecular mechanics' interpretation and AuNP's plasmonic nature. We performed partial charge quantum calculation of AuNPs using Au13 and Au55 models. The result showed that it has partial negative charges on the surface and partial positive charges on the inner part, indicating that the AuNP model should be composed of multiatom types. We tested the partial charge parameters of these gold (Au) atoms in classical molecular dynamics simulation (CMD) of AuNPs. The result showed that our parameters performed better in simulating the adsorption of Na+ and dicarboxy acetone in terms of consistency with surface charge density than the zero charges Au in the interface force field (IFF). We proposed that the multiple-charged AuNP model can be developed further into a simpler four-atom type of Au in a larger AuNP size.
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Affiliation(s)
- Regaputra S Janitra
- Biotechnology Master Program, Postgraduate School, Universitas Padjadjaran, Jl. Dipatiukur 35, Bandung 40132, West Java, Indonesia
| | - Wanda Destiarani
- Research Center for Molecular Biotechnology and Bioinformatics, Universitas Padjadjaran, Jl. Singaperbangsa 2, Bandung 40132, West Java, Indonesia
| | - Ari Hardianto
- Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Padjadjaran, Jl. Raya Bandung-Sumedang KM 21, Jatinangor 45363, West Java, Indonesia
- Research Center for Molecular Biotechnology and Bioinformatics, Universitas Padjadjaran, Jl. Singaperbangsa 2, Bandung 40132, West Java, Indonesia
| | - Umi Baroroh
- Research Center for Molecular Biotechnology and Bioinformatics, Universitas Padjadjaran, Jl. Singaperbangsa 2, Bandung 40132, West Java, Indonesia
- Department of Biotechnology, Indonesian School of Pharmacy, Jl. Soekarno Hatta No. 354, Bandung 40266, West Java, Indonesia
| | - Fauzian G Rohmatulloh
- Research Center for Molecular Biotechnology and Bioinformatics, Universitas Padjadjaran, Jl. Singaperbangsa 2, Bandung 40132, West Java, Indonesia
| | - Rustaman
- Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Padjadjaran, Jl. Raya Bandung-Sumedang KM 21, Jatinangor 45363, West Java, Indonesia
| | - Toto Subroto
- Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Padjadjaran, Jl. Raya Bandung-Sumedang KM 21, Jatinangor 45363, West Java, Indonesia
- Research Center for Molecular Biotechnology and Bioinformatics, Universitas Padjadjaran, Jl. Singaperbangsa 2, Bandung 40132, West Java, Indonesia
| | - Rukiah
- Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Padjadjaran, Jl. Raya Bandung-Sumedang KM 21, Jatinangor 45363, West Java, Indonesia
| | - Muhammad Yusuf
- Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Padjadjaran, Jl. Raya Bandung-Sumedang KM 21, Jatinangor 45363, West Java, Indonesia
- Research Center for Molecular Biotechnology and Bioinformatics, Universitas Padjadjaran, Jl. Singaperbangsa 2, Bandung 40132, West Java, Indonesia
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5
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Jensen F. Unifying Charge-Flow Polarization Models. J Chem Theory Comput 2023. [PMID: 37365806 DOI: 10.1021/acs.jctc.3c00341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2023]
Abstract
We show that several models where electric polarization in molecular systems is modeled by charge-flow between atoms can all be considered as different manifestations of a general underlying mathematical structure. The models can be classified according to whether they employ atomic or bond parameters and whether they employ atom/bond hardness or softness. We show that an ab initio calculated charge response kernel can be considered as the inverse screened Coulombic matrix projected onto the zero-charge subspace, and this may provide a method for deriving charge screening functions to be used in force fields. The analysis suggests that some models contain redundancies, and we argue that a parameterization of charge-flow models in terms of bond softness is preferable as it depends on local quantities and decay to zero upon bond dissociation, while bond hardness depends on global quantities and increases toward infinity upon bond dissociation.
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Affiliation(s)
- Frank Jensen
- Department of Chemistry, Aarhus University, Langelandsgade 140, Aarhus DK-8000, Denmark
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6
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Strelnikov IA, Kovaleva NA, Klinov AP, Zubova EA. C-B-A Test of DNA Force Fields. ACS OMEGA 2023; 8:10253-10265. [PMID: 36969447 PMCID: PMC10034787 DOI: 10.1021/acsomega.2c07781] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Accepted: 02/24/2023] [Indexed: 06/18/2023]
Abstract
The DNA duplex may be locally strongly bent in complexes with proteins, for example, with polymerases or in a nucleosome. At such bends, the DNA helix is locally in the noncanonical forms A (with a narrow major groove and a large amount of north sugars) or C (with a narrow minor groove and a large share of BII phosphates). To model the formation of such complexes by molecular dynamics methods, the force field is required to reproduce these conformational transitions for a naked DNA. We analyzed the available experimental data on the B-C and B-A transitions under the conditions easily implemented in modeling: in an aqueous NaCl solution. We selected six DNA duplexes which conformations at different salt concentrations are known reliably enough. At low salt concentrations, poly(GC) and poly(A) are in the B-form, classical and slightly shifted to the A-form, respectively. The duplexes ATAT and GGTATACC have a strong and salt concentration dependent bias toward the A-form. The polymers poly(AC) and poly(G) take the C- and A-forms, respectively, at high salt concentrations. The reproduction of the behavior of these oligomers can serve as a test for the balance of interactions between the base stacking and the conformational flexibility of the sugar-phosphate backbone in a DNA force field. We tested the AMBER bsc1 and CHARMM36 force fields and their hybrids, and we failed to reproduce the experiment. In all the force fields, the salt concentration dependence is very weak. The known B-philicity of the AMBER force field proved to result from the B-philicity of its excessively strong base stacking. In the CHARMM force field, the B-form is a result of a fragile balance between the A-philic base stacking (especially for G:C pairs) and the C-philic backbone. Finally, we analyzed some recent simulations of the LacI-, SOX-4-, and Sac7d-DNA complex formation in the framework of the AMBER force field.
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7
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The development of nucleic acids force fields: From an unchallenged past to a competitive future. Biophys J 2022:S0006-3495(22)03932-7. [PMID: 36540025 PMCID: PMC10398263 DOI: 10.1016/j.bpj.2022.12.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 11/08/2022] [Accepted: 12/15/2022] [Indexed: 12/24/2022] Open
Abstract
Molecular dynamics simulations have strongly matured as a method to study biomolecular processes. Their validity, however, is determined by the accuracy of the underlying force fields that describe the forces between all atoms. In this article, we review the development of nucleic acids force fields. We describe the early attempts in the 1990s and emphasize their strong influence on recent force fields. State-of-the-art force fields still use the same Lennard-Jones parameters derived 25 years ago in spite of the fact that these parameters were in general not fitted for nucleic acids. In addition, electrostatic parameters also are deprecated, which may explain some of the current force field deficiencies. We compare different force fields for various systems and discuss new tests of the recently developed Tumuc1 force field. The OL-force fields and Tumuc1 are arguably the best force fields to describe the DNA double helix. However, no force field is flawless. In particular, the description of sugar-puckering remains a problem for nucleic acids force fields. Future refinements are required, so we review methods for force field refinement and give an outlook to the future of force fields.
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8
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The Importance of Charge Transfer and Solvent Screening in the Interactions of Backbones and Functional Groups in Amino Acid Residues and Nucleotides. Int J Mol Sci 2022; 23:ijms232113514. [PMID: 36362296 PMCID: PMC9654426 DOI: 10.3390/ijms232113514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 10/26/2022] [Accepted: 10/28/2022] [Indexed: 11/06/2022] Open
Abstract
Quantum mechanical (QM) calculations at the level of density-functional tight-binding are applied to a protein–DNA complex (PDB: 2o8b) consisting of 3763 atoms, averaging 100 snapshots from molecular dynamics simulations. A detailed comparison of QM and force field (Amber) results is presented. It is shown that, when solvent screening is taken into account, the contributions of the backbones are small, and the binding of nucleotides in the double helix is governed by the base–base interactions. On the other hand, the backbones can make a substantial contribution to the binding of amino acid residues to nucleotides and other residues. The effect of charge transfer on the interactions is also analyzed, revealing that the actual charge of nucleotides and amino acid residues can differ by as much as 6 and 8% from the formal integer charge, respectively. The effect of interactions on topological models (protein -residue networks) is elucidated.
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9
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Jing Z, Ren P. Molecular Dynamics Simulations of Protein RNA Complexes by Using an Advanced Electrostatic Model. J Phys Chem B 2022; 126:7343-7353. [PMID: 36107618 PMCID: PMC9530969 DOI: 10.1021/acs.jpcb.2c05278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Protein-RNA interactions are integral to the biological functions of RNA. It is well recognized that molecular dynamics (MD) simulations of protein-RNA complexes are more challenging than those of each component. The difficulty arises from the strong electrostatic interactions and the delicate balance between various types of physical forces at the interface. Previously, MD simulations of protein-RNA complexes have predominantly employed fixed-charge force fields. Although force field modifications have been developed to address problems identified in the simulations, some protein-RNA structures are still hard to reproduce by simulations. Here, we present MD simulations of two representative protein-RNA complexes using the AMOEBA polarizable force field. The van der Waals parameters were refined to reproduce accurate quantum-mechanical data of base-base and base-amino acid interactions. It was found that the refined parameters produced a more stable hydrogen-bond network in the interface. One of the complexes remained stable during the short simulations, whereas it could quickly break down in previous simulations using fixed-charge force fields. There was reversible breaking and formation of hydrogen bonds that are observed in the crystal structure, which may indicate the difference in solution and crystal structures. While further improvement and validation of the force fields are still needed, this work demonstrates that polarizable force fields are promising for the study of protein-RNA complexes.
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Affiliation(s)
- Zhifeng Jing
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712
| | - Pengyu Ren
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712
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10
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Piomponi V, Fröhlking T, Bernetti M, Bussi G. Molecular Simulations Matching Denaturation Experiments for N 6-Methyladenosine. ACS CENTRAL SCIENCE 2022; 8:1218-1228. [PMID: 36032773 PMCID: PMC9413829 DOI: 10.1021/acscentsci.2c00565] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Indexed: 06/15/2023]
Abstract
Post-transcriptional modifications are crucial for RNA function and can affect its structure and dynamics. Force-field-based classical molecular dynamics simulations are a fundamental tool to characterize biomolecular dynamics, and their application to RNA is flourishing. Here, we show that the set of force-field parameters for N6-methyladenosine (m6A) developed for the commonly used AMBER force field does not reproduce duplex denaturation experiments and, specifically, cannot be used to describe both paired and unpaired states. Then, we use reweighting techniques to derive new parameters matching available experimental data. The resulting force field can be used to properly describe paired and unpaired m6A in both syn and anti conformation, which thus opens the way to the use of molecular simulations to investigate the effects of N6 methylations on RNA structural dynamics.
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11
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Barcza B, Szirmai ÁB, Szántó KJ, Tajti A, Szalay PG. Comparison of approximate intermolecular potentials for ab initio fragment calculations on medium sized N-heterocycles. J Comput Chem 2022; 43:1079-1093. [PMID: 35478353 PMCID: PMC9321956 DOI: 10.1002/jcc.26866] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 03/26/2022] [Accepted: 03/29/2022] [Indexed: 01/15/2023]
Abstract
The ground state intermolecular potential of bimolecular complexes of N‐heterocycles is analyzed for the impact of individual terms in the interaction energy as provided by various, conceptually different theories. Novel combinations with several formulations of the electrostatic, Pauli repulsion, and dispersion contributions are tested at both short‐ and long‐distance sides of the potential energy surface, for various alignments of the pyrrole dimer as well as the cytosine–uracil complex. The integration of a DFT/CCSD density embedding scheme, with dispersion terms from the effective fragment potential (EFP) method is found to provide good agreement with a reference CCSD(T) potential overall; simultaneously, a quantum mechanics/molecular mechanics approach using CHELPG atomic point charges for the electrostatic interaction, augmented by EFP dispersion and Pauli repulsion, comes also close to the reference result. Both schemes have the advantage of not relying on predefined force fields; rather, the interaction parameters can be determined for the system under study, thus being excellent candidates for ab initio modeling.
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Affiliation(s)
- Bónis Barcza
- Institute of Chemistry, Laboratory of Theoretical Chemistry, ELTE Eötvös Loránd University, Budapest, Hungary
| | - Ádám B Szirmai
- Institute of Chemistry, Laboratory of Theoretical Chemistry, ELTE Eötvös Loránd University, Budapest, Hungary
| | - Katalin J Szántó
- Institute of Chemistry, Laboratory of Theoretical Chemistry, ELTE Eötvös Loránd University, Budapest, Hungary
| | - Attila Tajti
- Institute of Chemistry, Laboratory of Theoretical Chemistry, ELTE Eötvös Loránd University, Budapest, Hungary
| | - Péter G Szalay
- Institute of Chemistry, Laboratory of Theoretical Chemistry, ELTE Eötvös Loránd University, Budapest, Hungary
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12
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Mlýnský V, Janeček M, Kührová P, Fröhlking T, Otyepka M, Bussi G, Banáš P, Šponer J. Toward Convergence in Folding Simulations of RNA Tetraloops: Comparison of Enhanced Sampling Techniques and Effects of Force Field Modifications. J Chem Theory Comput 2022; 18:2642-2656. [PMID: 35363478 DOI: 10.1021/acs.jctc.1c01222] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Atomistic molecular dynamics simulations represent an established technique for investigation of RNA structural dynamics. Despite continuous development, contemporary RNA simulations still suffer from suboptimal accuracy of empirical potentials (force fields, ffs) and sampling limitations. Development of efficient enhanced sampling techniques is important for two reasons. First, they allow us to overcome the sampling limitations, and second, they can be used to quantify ff imbalances provided they reach a sufficient convergence. Here, we study two RNA tetraloops (TLs), namely the GAGA and UUCG motifs. We perform extensive folding simulations and calculate folding free energies (ΔGfold°) with the aim to compare different enhanced sampling techniques and to test several modifications of the nonbonded terms extending the AMBER OL3 RNA ff. We demonstrate that replica-exchange solute tempering (REST2) simulations with 12-16 replicas do not show any sign of convergence even when extended to a timescale of 120 μs per replica. However, the combination of REST2 with well-tempered metadynamics (ST-MetaD) achieves good convergence on a timescale of 5-10 μs per replica, improving the sampling efficiency by at least 2 orders of magnitude. Effects of ff modifications on ΔGfold° energies were initially explored by the reweighting approach and then validated by new simulations. We tested several manually prepared variants of the gHBfix potential which improve stability of the native state of both TLs by ∼2 kcal/mol. This is sufficient to conveniently stabilize the folded GAGA TL while the UUCG TL still remains under-stabilized. Appropriate adjustment of van der Waals parameters for C-H···O5' base-phosphate interaction may further stabilize the native states of both TLs by ∼0.6 kcal/mol.
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Affiliation(s)
- Vojtěch Mlýnský
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic
| | - Michal Janeček
- Department of Physical Chemistry, Faculty of Science, Palacký University, tř. 17 listopadu 12, 771 46 Olomouc, Czech Republic
| | - Petra Kührová
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic.,Regional Centre of Advanced Technologies and Materials, Czech Advanced Technology and Research Institute (CATRIN), Palacký University Olomouc, Šlechtitelů 27, 779 00 Olomouc, Czech Republic
| | - Thorben Fröhlking
- Scuola Internazionale Superiore di Studi Avanzati, SISSA, via Bonomea 265, 34136 Trieste, Italy
| | - Michal Otyepka
- Regional Centre of Advanced Technologies and Materials, Czech Advanced Technology and Research Institute (CATRIN), Palacký University Olomouc, Šlechtitelů 27, 779 00 Olomouc, Czech Republic.,IT4Innovations, VSB─Technical University of Ostrava, 17. listopadu 2172/15, 708 00 Ostrava-Poruba, Czech Republic
| | - Giovanni Bussi
- Scuola Internazionale Superiore di Studi Avanzati, SISSA, via Bonomea 265, 34136 Trieste, Italy
| | - Pavel Banáš
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic.,Regional Centre of Advanced Technologies and Materials, Czech Advanced Technology and Research Institute (CATRIN), Palacký University Olomouc, Šlechtitelů 27, 779 00 Olomouc, Czech Republic
| | - Jiří Šponer
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic.,Regional Centre of Advanced Technologies and Materials, Czech Advanced Technology and Research Institute (CATRIN), Palacký University Olomouc, Šlechtitelů 27, 779 00 Olomouc, Czech Republic
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13
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Mikhailovskii O, Xue Y, Skrynnikov NR. Modeling a unit cell: crystallographic refinement procedure using the biomolecular MD simulation platform Amber. IUCRJ 2022; 9:114-133. [PMID: 35059216 PMCID: PMC8733891 DOI: 10.1107/s2052252521011891] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 11/09/2021] [Indexed: 06/14/2023]
Abstract
A procedure has been developed for the refinement of crystallographic protein structures based on the biomolecular simulation program Amber. The procedure constructs a model representing a crystal unit cell, which generally contains multiple protein molecules and is fully hydrated with TIP3P water. Periodic boundary conditions are applied to the cell in order to emulate the crystal lattice. The refinement is conducted in the form of a specially designed short molecular-dynamics run controlled by the Amber ff14SB force field and the maximum-likelihood potential that encodes the structure-factor-based restraints. The new Amber-based refinement procedure has been tested on a set of 84 protein structures. In most cases, the new procedure led to appreciably lower R free values compared with those reported in the original PDB depositions or obtained by means of the industry-standard phenix.refine program. In particular, the new method has the edge in refining low-accuracy scrambled models. It has also been successful in refining a number of molecular-replacement models, including one with an r.m.s.d. of 2.15 Å. In addition, Amber-refined structures consistently show superior MolProbity scores. The new approach offers a highly realistic representation of protein-protein interactions in the crystal, as well as of protein-water interactions. It also offers a realistic representation of protein crystal dynamics (akin to ensemble-refinement schemes). Importantly, the method fully utilizes the information from the available diffraction data, while relying on state-of-the-art molecular-dynamics modeling to assist with those elements of the structure that do not diffract well (for example mobile loops or side chains). Finally, it should be noted that the protocol employs no tunable parameters, and the calculations can be conducted in a matter of several hours on desktop computers equipped with graphical processing units or using a designated web service.
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Affiliation(s)
- Oleg Mikhailovskii
- Laboratory of Biomolecular NMR, St Petersburg State University, St Petersburg 199034, Russian Federation
- Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Yi Xue
- School of Life Sciences, Tsinghua University, Beijing 100084, People's Republic of China
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, People's Republic of China
- Tsinghua University-Peking University Joint Center for Life Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - Nikolai R Skrynnikov
- Laboratory of Biomolecular NMR, St Petersburg State University, St Petersburg 199034, Russian Federation
- Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA
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14
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Seo B, Lin ZY, Zhao Q, Webb MA, Savoie BM. Topology Automated Force-Field Interactions (TAFFI): A Framework for Developing Transferable Force Fields. J Chem Inf Model 2021; 61:5013-5027. [PMID: 34533949 DOI: 10.1021/acs.jcim.1c00491] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Force-field development has undergone a revolution in the past decade with the proliferation of quantum chemistry based parametrizations and the introduction of machine learning approximations of the atomistic potential energy surface. Nevertheless, transferable force fields with broad coverage of organic chemical space remain necessary for applications in materials and chemical discovery where throughput, consistency, and computational cost are paramount. Here, we introduce a force-field development framework called Topology Automated Force-Field Interactions (TAFFI) for developing transferable force fields of varying complexity against an extensible database of quantum chemistry calculations. TAFFI formalizes the concept of atom typing and makes it the basis for generating systematic training data that maintains a one-to-one correspondence with force-field terms. This feature makes TAFFI arbitrarily extensible to new chemistries while maintaining internal consistency and transferability. As a demonstration of TAFFI, we have developed a fixed-charge force-field, TAFFI-gen, from scratch that includes coverage for common organic functional groups that is comparable to established transferable force fields. The performance of TAFFI-gen was benchmarked against OPLS and GAFF for reproducing several experimental properties of 87 organic liquids. The consistent performance of these force fields, despite their distinct origins, validates the TAFFI framework while also providing evidence of the representability limitations of fixed-charge force fields.
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Affiliation(s)
- Bumjoon Seo
- Davidson School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47906, United States
| | - Zih-Yu Lin
- Davidson School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47906, United States
| | - Qiyuan Zhao
- Davidson School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47906, United States
| | - Michael A Webb
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08540, United States
| | - Brett M Savoie
- Davidson School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47906, United States
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15
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Negi I, Mahmi AS, Seelam Prabhakar P, Sharma P. Molecular Dynamics Simulations of the Aptamer Domain of Guanidinium Ion Binding Riboswitch ykkC-III: Structural Insights into the Discrimination of Cognate and Alternate Ligands. J Chem Inf Model 2021; 61:5243-5255. [PMID: 34609872 DOI: 10.1021/acs.jcim.1c01022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Guanidinium ion is a toxic cellular metabolite. The ykkC-III riboswitch, an mRNA stretch, regulates the gene expression by undergoing a conformational change in response to the binding of a free guanidinium ion and thereby plays a potentially important role in alleviating guanidinium toxicity in cells. An experimental crystal structure of the guanidinium-bound aptamer domain of the riboswitch from Thermobifida Fusca revealed the overall RNA architecture and mapped the specific noncovalent interactions that stabilize the ligand within the binding pocket aptamer. However, details of how the aptamer domain discriminates the cognate ligand from its closest structurally analogous physiological metabolites (arginine and urea), and how the binding of cognate ligand arrays information from the aptamer domain to the expression platform for regulating the gene expression, are not well understood. To fill this void, we perform a cumulative of 2 μs all-atom explicit-solvent molecular dynamics (MD) simulations on the full aptamer domain, augmented with quantum-chemical calculations on the ligand-binding pocket, to compare the structural and dynamical details of the guanidinium-bound state with the arginine or urea bound states, as well as the unbound (open) state. Analysis of the ligand-binding pocket reveals that due to unfavorable interactions with the binding-pocket residues, urea cannot bind the aptamer domain and thereby cannot alter the gene expression. Although interaction of the guanidyl moiety of arginine within the binding pocket is either comparable or stronger than the guanidinium ion, additional non-native hydrogen-bonding networks, as well as differences in the dynamical details of the arginine-bound state, explain why arginine cannot transmit the information from the aptamer domain to the expression platform. Based on our simulations, we propose a mechanism of how the aptamer domain communicates with the expression platform. Overall, our work provides interesting insights into the ligand recognition by a specific class of riboswitches and may hopefully inspire future studies to further understand the gene regulation by riboswitches.
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Affiliation(s)
- Indu Negi
- Computational Biochemistry Laboratory, Department of Chemistry and Centre for Advanced Studies in Chemistry, Panjab University, Chandigarh 160014, India
| | - Amanpreet Singh Mahmi
- Computational Biochemistry Laboratory, Department of Chemistry and Centre for Advanced Studies in Chemistry, Panjab University, Chandigarh 160014, India
| | - Preethi Seelam Prabhakar
- Center for Computational Natural Sciences and Bioinformatics, International Institute of Information Technology (IIIT-H), Gachibowli, Hyderabad, Telangana 500032, India
| | - Purshotam Sharma
- Computational Biochemistry Laboratory, Department of Chemistry and Centre for Advanced Studies in Chemistry, Panjab University, Chandigarh 160014, India
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