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Mittal S, Nisler C, Szostak JW. Simulations predict preferred Mg 2+ coordination in a nonenzymatic primer-extension reaction center. Biophys J 2024; 123:1579-1591. [PMID: 38702884 PMCID: PMC11214020 DOI: 10.1016/j.bpj.2024.04.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 04/24/2024] [Accepted: 04/30/2024] [Indexed: 05/06/2024] Open
Abstract
The mechanism by which genetic information was copied prior to the evolution of ribozymes is of great interest because of its importance to the origin of life. The most effective known process for the nonenzymatic copying of an RNA template is primer extension by a two-step pathway in which 2-aminoimidazole-activated nucleotides first react with each other to form an imidazolium-bridged intermediate that subsequently reacts with the primer. Reaction kinetics, structure-activity relationships, and X-ray crystallography have provided insight into the overall reaction mechanism, but many puzzles remain. In particular, high concentrations of Mg2+ are required for efficient primer extension, but the mechanism by which Mg2+ accelerates primer extension remains unknown. By analogy with the mechanism of DNA and RNA polymerases, a role for Mg2+ in facilitating the deprotonation of the primer 3'-hydroxyl is often assumed, but no catalytic metal ion is seen in crystal structures of the primer-extension complex. To explore the potential effects of Mg2+ binding in the reaction center, we performed atomistic molecular dynamics simulations of a series of modeled complexes in which a Mg2+ ion was placed in the reaction center with inner-sphere coordination with different sets of functional groups. Our simulations suggest that coordination of a Mg2+ ion with both O3' of the terminal primer nucleotide and the pro-Sp nonbridging oxygen of the reactive phosphate of an imidazolium-bridged dinucleotide would help to pre-organize the structure of the primer/template substrate complex to favor the primer-extension reaction. Our results suggest that the catalytic metal ion may play an important role in overcoming electrostatic repulsion between a deprotonated O3' and the reactive phosphate of the bridged dinucleotide and lead to testable predictions of the mode of Mg2+ binding that is most relevant to catalysis of primer extension.
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Affiliation(s)
- Shriyaa Mittal
- Howard Hughes Medical Institute, Department of Molecular Biology, Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts; Department of Genetics, Harvard Medical School, Boston, Massachusetts
| | - Collin Nisler
- Howard Hughes Medical Institute, Department of Chemistry, University of Chicago, Chicago, Illinois
| | - Jack W Szostak
- Howard Hughes Medical Institute, Department of Molecular Biology, Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts; Department of Genetics, Harvard Medical School, Boston, Massachusetts; Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts; Howard Hughes Medical Institute, Department of Chemistry, University of Chicago, Chicago, Illinois.
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Michel HM, Lemkul JA. Base pair dynamics, electrostatics, and thermodynamics at the LTR-III quadruplex:duplex junction. Biophys J 2024; 123:1129-1138. [PMID: 38576161 PMCID: PMC11079942 DOI: 10.1016/j.bpj.2024.03.042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 03/10/2024] [Accepted: 03/29/2024] [Indexed: 04/06/2024] Open
Abstract
G-quadruplexes (GQs) play key regulatory roles within the human genome and have also been identified to play similar roles in other eukaryotes, bacteria, archaea, and viruses. Human immunodeficiency virus 1, the etiological agent of acquired immunodeficiency syndrome, can form two GQs in its long terminal repeat (LTR) promoter region, each of which act to regulate viral gene expression in opposing manners. The major LTR GQ, called LTR-III, is a distinct hybrid GQ containing a 12-nucleotide duplex loop attached to the quadruplex motif. The resulting quadruplex:duplex junction (QDJ) has been hypothesized to serve as a selective drug targeting site. To better understand the dynamics of this QDJ, we performed conventional and enhanced-sampling molecular dynamics simulations using the Drude-2017 force field. We observed unbiased and reversible formation of additional base pairs in the QDJ, between Ade4:Thy14 and Gua3:Thy14. Both base pairs were electrostatically favored, but geometric constraints within the junction may drive the formation of, and preference for, the Ade4:Thy14 base pair. Finally, we demonstrated that the base pairs are separated only by small energy barriers that may enable transitions between both base-paired states. Together, these simulations provide new insights into the dynamics, electrostatics, and thermodynamics of the LTR-III QDJ.
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Affiliation(s)
- Haley M Michel
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia
| | - Justin A Lemkul
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia; Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia.
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Polêto MD, Lemkul JA. Differences in Conformational Sampling and Intrinsic Electric Fields Drive Ion Binding in Telomeric and TERRA G-Quadruplexes. J Chem Inf Model 2023; 63:6851-6862. [PMID: 37847037 PMCID: PMC10841373 DOI: 10.1021/acs.jcim.3c01305] [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: 10/18/2023]
Abstract
The formation of G-quadruplexes (GQs) occurs in guanine-rich sequences of DNA and RNA, producing highly stable and structurally diverse noncanonical nucleic acid structures. GQs play crucial roles in regulating transcription, translation, and replication and maintaining the genome, among others; thus, changes to their structures can lead to diseases such as cancer. Previous studies using polarizable molecular dynamics simulations have shown differences in ion binding properties between telomeric and telomeric repeat-containing RNA GQs despite architectural similarities. Here, we used volume-based metadynamics and repulsive potential simulations in conjunction with polarizable force fields to quantify the impact of ion binding on the GQ dynamics and ion binding free energies. Furthermore, we describe how GQs exert electric fields on their surroundings to link dynamics with variations in the electronic structure. Our findings provide new insights into the energetic, physical, and conformational properties of GQs and expose subtle but important differences between DNA and RNA GQs with the same fold.
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Affiliation(s)
- Marcelo D Polêto
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Justin A Lemkul
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
- Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia 24061, United States
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Polêto MD, Lemkul JA. Differences in Conformational Sampling and Intrinsic Electric Fields Drive Ion Binding in Telomeric and TERRA G-Quadruplexes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.10.552810. [PMID: 37645825 PMCID: PMC10461924 DOI: 10.1101/2023.08.10.552810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
The formation of G-quadruplexes (GQs) occurs in guanine-rich sequences of DNA and RNA, producing highly stable and structurally diverse noncanonical nucleic acid structures. GQs play crucial roles in regulating transcription, translation, and replication; and maintaining the genome, among others, thus changes to their structures can lead to diseases such as cancer. Previous studies using polarizable molecular dynamics simulations have shown differences in ion binding properties between telomeric and TERRA GQs despite architectural similarities. Here, we used volume-based metadynamics and repulsive potential simulations in conjunction with polarizable force fields to quantify the impact of ion binding on GQ dynamics and ion binding free energies. Furthermore, we describe how GQs exert electric fields on their surroundings to link dynamics with variations in electronic structure. Our findings provide new insights into the energetic, physical, and conformational properties of GQs and expose subtle, but important, differences between DNA and RNA GQs with the same fold.
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Affiliation(s)
- Marcelo D Polêto
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, United States
| | - Justin A Lemkul
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, United States
- Center for Drug Discovery, Virginia Tech, Blacksburg, VA 24061, United States
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Salsbury A, Michel HM, Lemkul JA. Ion-Dependent Conformational Plasticity of Telomeric G-Hairpins and G-Quadruplexes. ACS OMEGA 2022; 7:23368-23379. [PMID: 35847338 PMCID: PMC9280957 DOI: 10.1021/acsomega.2c01600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Telomeric DNA is guanine-rich and can adopt structures such as G-quadruplexes (GQs) and G-hairpins. Telomeric GQs influence genome stability and telomerase activity, making understanding of enzyme-GQ interactions and dynamics important for potential drug design. GQs have a characteristic tetrad core, which is connected by loop regions. Within this architecture are G-hairpins, fold-back motifs that are thought to represent the first intermediate in GQ folding. To better understand the relationship between G-hairpin motifs and GQs, we performed polarizable simulations of a two-tetrad telomeric GQ and an isolated SC11 telomeric G-hairpin. The telomeric GQ contains a G-triad, which functions as part of the tetrad core or linker regions, depending on local conformational change. This triad and another motif below the tetrad core frequently bound ions and may represent druggable sites. Further, we observed the unbiased formation of a G-triad and a G-tetrad in simulations of the SC11 G-hairpin and found that cations can be partially hydrated while facilitating the formation of these motifs. Finally, we demonstrated that K+ ions form specific interactions with guanine bases, while Na+ ions interact nonspecifically with bases in the structure. Together, these simulations provide new insights into the influence of ions on GQs, G-hairpins, and G-triad motifs.
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Affiliation(s)
- Alexa
M. Salsbury
- Department
of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Haley M. Michel
- Department
of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Justin A. Lemkul
- Department
of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
- Center
for Drug Discovery, Virginia Tech, Blacksburg, Virginia 24061, United States
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Ribaudo G, Ongaro A, Oselladore E, Memo M, Gianoncelli A. Combining Electrospray Mass Spectrometry (ESI-MS) and Computational Techniques in the Assessment of G-Quadruplex Ligands: A Hybrid Approach to Optimize Hit Discovery. J Med Chem 2021; 64:13174-13190. [PMID: 34510895 PMCID: PMC8474113 DOI: 10.1021/acs.jmedchem.1c00962] [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] [Indexed: 12/05/2022]
Abstract
![]()
Guanine-rich sequences
forming G-quadruplexes (GQs) are present
in several genomes, ranging from viral to human. Given their peculiar
localization, the induction of GQ formation or GQ stabilization with
small molecules represents a strategy for interfering with crucial
biological functions. Investigating the recognition event at the molecular
level, with the aim of fully understanding the triggered pharmacological
effects, is challenging. Native electrospray ionization mass spectrometry
(ESI-MS) is being optimized to study these noncovalent assemblies.
Quantitative parameters retrieved from ESI-MS studies, such as binding
affinity, the equilibrium binding constant, and sequence selectivity,
will be overviewed. Computational experiments supporting the ESI-MS
investigation and boosting its efficiency in the search for GQ ligands
will also be discussed with practical examples. The combination of
ESI-MS and in silico techniques in a hybrid high-throughput-screening
workflow represents a valuable tool for the medicinal chemist, providing
data on the quantitative and structural aspects of ligand–GQ
interactions.
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Affiliation(s)
- Giovanni Ribaudo
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123 Brescia, Italy
| | - Alberto Ongaro
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123 Brescia, Italy
| | - Erika Oselladore
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123 Brescia, Italy
| | - Maurizio Memo
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123 Brescia, Italy
| | - Alessandra Gianoncelli
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123 Brescia, Italy
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Li N, Gao Y, Qiu F, Zhu T. Benchmark Force Fields for the Molecular Dynamic Simulation of G-Quadruplexes. Molecules 2021; 26:5379. [PMID: 34500812 PMCID: PMC8434458 DOI: 10.3390/molecules26175379] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 08/30/2021] [Accepted: 08/31/2021] [Indexed: 11/29/2022] Open
Abstract
G-quadruplexes have drawn widespread attention for serving as a potential anti-cancer target and their application in material science. Molecular dynamics (MD) simulation is the key theoretical tool in the study of GQ's structure-function relationship. In this article, we systematically benchmarked the five force fields of parmbsc0, parmbsc1, OL15, AMOEBA, and Drude2017 on the MD simulation of G-quadruplex from four aspects: structural stability, central ion channel stability, description of Hoogsteen hydrogen bond network, and description of the main chain dihedral angle. The results show that the overall performance of the Drude force field is the best. Although there may be a certain over-polarization effect, it is still the best choice for the MD simulation of G-quadruplexes.
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Affiliation(s)
- Na Li
- Shanghai Engineering Research Center of Molecular Therapeutics & New Drug Development, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200241, China;
| | - Ya Gao
- School of Mathematics, Physics and Statistics, Shanghai University of Engineering Science, Shanghai 201620, China
| | - Feng Qiu
- Institute of Artificial Intelligence on Education, Shanghai Normal University, Shanghai 200234, China
| | - Tong Zhu
- Shanghai Engineering Research Center of Molecular Therapeutics & New Drug Development, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200241, China;
- NYU-ECNU Center for Computational Chemistry, New York University Shanghai, Shanghai 200062, China
- Shandong Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou 253023, China
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