1
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Jurkowski M, Kogut M, Sappati S, Czub J. Why Are Left-Handed G-Quadruplexes Scarce? J Phys Chem Lett 2024; 15:3142-3148. [PMID: 38477716 PMCID: PMC10961827 DOI: 10.1021/acs.jpclett.3c03589] [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] [Received: 12/23/2023] [Revised: 02/27/2024] [Accepted: 03/08/2024] [Indexed: 03/14/2024]
Abstract
G-quadruplexes (G4s) are nucleic acid structures crucial for the regulation of gene expression and genome maintenance. While they hold promise as nanodevice components, achieving desired G4 folds requires understanding the interplay between stability and structural properties, like helicity. Although right-handed G4 structures dominate the experimental data, the molecular basis for this preference over left-handed helicity is unclear. To address this, we employ all-atom molecular dynamics simulations and quantum chemical methods. Our results reveal that right-handed G4s exhibit greater thermodynamic and kinetic stability as a result of favorable sugar-phosphate backbone conformations in guanine tracts. Moreover, while hydrogen-bonding patterns influence helicity-specific G4 loop conformations, they minimally affect stability differences. We also elucidate the strong correlation between helicity and the strand progression direction, essential for G4 structures. These findings deepen our understanding of G4s, providing molecular-level insights into their structural and energetic preferences, which could inform the design of novel nanodevices.
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Affiliation(s)
- Michał Jurkowski
- Department
of Physical Chemistry, Gdańsk University
of Technology, Narutowicza Street 11/12, 80-233 Gdańsk, Poland
| | - Mateusz Kogut
- Department
of Physical Chemistry, Gdańsk University
of Technology, Narutowicza Street 11/12, 80-233 Gdańsk, Poland
| | - Subrahmanyam Sappati
- Department
of Physical Chemistry, Gdańsk University
of Technology, Narutowicza Street 11/12, 80-233 Gdańsk, Poland
- BioTechMed
Center, Gdańsk University of Technology, Narutowicza Street 11/12, 80-233 Gdańsk, Poland
| | - Jacek Czub
- Department
of Physical Chemistry, Gdańsk University
of Technology, Narutowicza Street 11/12, 80-233 Gdańsk, Poland
- BioTechMed
Center, Gdańsk University of Technology, Narutowicza Street 11/12, 80-233 Gdańsk, Poland
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2
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Stark M, Levin M, Ulitsky I, Assaraf YG. Folylpolyglutamate synthetase mRNA G-quadruplexes regulate its cell protrusion localization and enhance a cancer cell invasive phenotype upon folate repletion. BMC Biol 2023; 21:13. [PMID: 36721160 PMCID: PMC9889130 DOI: 10.1186/s12915-023-01525-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Accepted: 01/23/2023] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Folates are crucial for the biosynthesis of nucleotides and amino acids, essential for cell proliferation and development. Folate deficiency induces DNA damage, developmental defects, and tumorigenicity. The obligatory enzyme folylpolyglutamate synthetase (FPGS) mediates intracellular folate retention via cytosolic and mitochondrial folate polyglutamylation. Our previous paper demonstrated the association of the cytosolic FPGS (cFPGS) with the cytoskeleton and various cell protrusion proteins. Based on these recent findings, the aim of the current study was to investigate the potential role of cFPGS at cell protrusions. RESULTS Here we uncovered a central role for two G-quadruplex (GQ) motifs in the 3'UTR of FPGS mediating the localization of cFPGS mRNA and protein at cell protrusions. Using the MBSV6-loop reporter system and fluorescence microscopy, we demonstrate that following folate deprivation, cFPGS mRNA is retained in the endoplasmic reticulum, whereas upon 15 min of folate repletion, this mRNA is rapidly translocated to cell protrusions in a 3'UTR- and actin-dependent manner. The actin dependency of this folate-induced mRNA translocation is shown by treatment with Latrunculin B and inhibitors of the Ras homolog family member A (RhoA) pathway. Upon folate repletion, the FPGS 3'UTR GQs induce an amoeboid/mesenchymal hybrid cell phenotype during migration and invasion through a collagen gel matrix. Targeted disruption of the 3'UTR GQ motifs by introducing point mutations or masking them by antisense oligonucleotides abrogated cell protrusion targeting of cFPGS mRNA. CONCLUSIONS Collectively, the GQ motifs within the 3'UTR of FPGS regulate its transcript and protein localization at cell protrusions in response to a folate cue, inducing cancer cell invasive phenotype. These novel findings suggest that the 3'UTR GQ motifs of FPGS constitute an attractive druggable target aimed at inhibition of cancer invasion and metastasis.
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Affiliation(s)
- Michal Stark
- grid.6451.60000000121102151The Fred Wyszkowski Cancer Research Laboratory, Department of Biology, Technion-Israel Institute of Technology, 3200003 Haifa, Israel
| | - May Levin
- grid.6451.60000000121102151The Fred Wyszkowski Cancer Research Laboratory, Department of Biology, Technion-Israel Institute of Technology, 3200003 Haifa, Israel ,grid.507132.2Present address: May Levin, MeMed Diagnostics Ltd, Tirat Carmel, Israel
| | - Igor Ulitsky
- grid.13992.300000 0004 0604 7563Department of Immunology and Regenerative Biology and Department of Molecular Neuroscience, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Yehuda G. Assaraf
- grid.6451.60000000121102151The Fred Wyszkowski Cancer Research Laboratory, Department of Biology, Technion-Israel Institute of Technology, 3200003 Haifa, Israel
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3
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Bie L, Wang Y, Jiang F, Xiao Z, Zhang L, Wang J. Insights into the binding mode of AS1411 aptamer to nucleolin. Front Mol Biosci 2022; 9:1025313. [PMID: 36262475 PMCID: PMC9574071 DOI: 10.3389/fmolb.2022.1025313] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 09/20/2022] [Indexed: 11/23/2022] Open
Abstract
AS1411 aptamer can function as a recognition probe to detect the cell surface nucleolin overexpressed in cancer cells, however, little is known about their binding process. This study proposed a feasible binding mode for the first time and provided atomic-level descriptions for the high affinity and specific binding of AS1411. The binding pose predicted by docking was screened using knowledge-based criteria, and a microsecond molecular dynamics (MD) simulation showed the stable existence of the predicted structure in the solution. Structural analysis shows that the unique capping of the 5′ end of AS1411 provides the specific binding with RBD1, and the interactions of hydrogen bond, salt bridge, and water-mediated network between AS1411 and RBD1,2 stabilize the binding. The calculation of per-residue decomposition emphasizes the dominant contribution of van der Waals energy and critical residues are screened. Our study provides the molecular basis of this specific binding and can guide rational AS1411-based aptamers design. Further insights require tight collaborations between the experiments and in silico studies.
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Affiliation(s)
- Lihua Bie
- Hubei Key Laboratory of Agricultural Bioinformatics, College of Informatics, Huazhong Agricultural University, Wuhan, China
- Laboratory for Advanced Analytical Technologies, Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
- Institute of Environmental Engineering, ETH Zürich, Zürich, Switzerland
| | - Yue Wang
- Hubei Key Laboratory of Agricultural Bioinformatics, College of Informatics, Huazhong Agricultural University, Wuhan, China
| | - Fuze Jiang
- Laboratory for Advanced Analytical Technologies, Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
- Institute of Environmental Engineering, ETH Zürich, Zürich, Switzerland
| | - Zhen Xiao
- Institute of Systems Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
- Suzhou Institute of Systems Medicine, Suzhou, China
| | - Lianjun Zhang
- Institute of Systems Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
- Suzhou Institute of Systems Medicine, Suzhou, China
| | - Jing Wang
- Laboratory for Advanced Analytical Technologies, Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
- Institute of Environmental Engineering, ETH Zürich, Zürich, Switzerland
- *Correspondence: Jing Wang,
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4
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Holoubek J, Bednářová K, Haviernik J, Huvarová I, Dvořáková Z, Černý J, Outlá M, Salát J, Konkol'ová E, Boura E, Růžek D, Vorlíčková M, Eyer L, Renčiuk D. Guanine quadruplexes in the RNA genome of the tick-borne encephalitis virus: their role as a new antiviral target and in virus biology. Nucleic Acids Res 2022; 50:4574-4600. [PMID: 35420134 PMCID: PMC9071444 DOI: 10.1093/nar/gkac225] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 03/21/2022] [Accepted: 03/25/2022] [Indexed: 12/11/2022] Open
Abstract
We have identified seven putative guanine quadruplexes (G4) in the RNA genome of tick-borne encephalitis virus (TBEV), a flavivirus causing thousands of human infections and numerous deaths every year. The formation of G4s was confirmed by biophysical methods on synthetic oligonucleotides derived from the predicted TBEV sequences. TBEV-5, located at the NS4b/NS5 boundary and conserved among all known flaviviruses, was tested along with its mutated variants for interactions with a panel of known G4 ligands, for the ability to affect RNA synthesis by the flaviviral RNA-dependent RNA polymerase (RdRp) and for effects on TBEV replication fitness in cells. G4-stabilizing TBEV-5 mutations strongly inhibited RdRp RNA synthesis and exhibited substantially reduced replication fitness, different plaque morphology and increased sensitivity to G4-binding ligands in cell-based systems. In contrast, strongly destabilizing TBEV-5 G4 mutations caused rapid reversion to the wild-type genotype. Our results suggest that there is a threshold of stability for G4 sequences in the TBEV genome, with any deviation resulting in either dramatic changes in viral phenotype or a rapid return to this optimal level of G4 stability. The data indicate that G4s are critical elements for efficient TBEV replication and are suitable targets to tackle TBEV infection.
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Affiliation(s)
- Jiří Holoubek
- Veterinary Research Institute, Emerging Viral Diseases, Brno CZ-62100, Czech Republic.,Department of Experimental Biology, Faculty of Science, Masaryk University, CZ-62500 Brno, Czech Republic.,Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, CZ-37005 Ceske Budejovice, Czech Republic
| | - Klára Bednářová
- Department of Biophysics of Nucleic Acids, Institute of Biophysics of the Czech Academy of Sciences, Brno CZ-61200, Czech Republic
| | - Jan Haviernik
- Veterinary Research Institute, Emerging Viral Diseases, Brno CZ-62100, Czech Republic.,Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, CZ-37005 Ceske Budejovice, Czech Republic
| | - Ivana Huvarová
- Veterinary Research Institute, Emerging Viral Diseases, Brno CZ-62100, Czech Republic
| | - Zuzana Dvořáková
- Department of Biophysics of Nucleic Acids, Institute of Biophysics of the Czech Academy of Sciences, Brno CZ-61200, Czech Republic
| | - Jiří Černý
- Faculty of Tropical Agrisciences, Czech University of Life Sciences Prague, CZ-16500 Prague, Czech Republic
| | - Martina Outlá
- Department of Biophysical Chemistry and Molecular Oncology, Institute of Biophysics of the Czech Academy of Sciences, Brno CZ-61200, Czech Republic.,National Centre for Biomolecular Research, Faculty of Science, Masaryk University, CZ-62500 Brno, Czech Republic
| | - Jiří Salát
- Veterinary Research Institute, Emerging Viral Diseases, Brno CZ-62100, Czech Republic.,Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, CZ-37005 Ceske Budejovice, Czech Republic
| | - Eva Konkol'ová
- Institute of Organic Chemistry and Biochemistry of the Czech Academy ofSciences, CZ-16000 Prague, Czech Republic
| | - Evzen Boura
- Institute of Organic Chemistry and Biochemistry of the Czech Academy ofSciences, CZ-16000 Prague, Czech Republic
| | - Daniel Růžek
- Veterinary Research Institute, Emerging Viral Diseases, Brno CZ-62100, Czech Republic.,Department of Experimental Biology, Faculty of Science, Masaryk University, CZ-62500 Brno, Czech Republic.,Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, CZ-37005 Ceske Budejovice, Czech Republic
| | - Michaela Vorlíčková
- Department of Biophysics of Nucleic Acids, Institute of Biophysics of the Czech Academy of Sciences, Brno CZ-61200, Czech Republic
| | - Luděk Eyer
- Veterinary Research Institute, Emerging Viral Diseases, Brno CZ-62100, Czech Republic.,Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, CZ-37005 Ceske Budejovice, Czech Republic
| | - Daniel Renčiuk
- Department of Biophysics of Nucleic Acids, Institute of Biophysics of the Czech Academy of Sciences, Brno CZ-61200, Czech Republic
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5
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Ozcan KA, Ghaffari LT, Haeusler AR. The effects of molecular crowding and CpG hypermethylation on DNA G-quadruplexes formed by the C9orf72 nucleotide repeat expansion. Sci Rep 2021; 11:23213. [PMID: 34853325 PMCID: PMC8636472 DOI: 10.1038/s41598-021-02041-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 11/09/2021] [Indexed: 01/09/2023] Open
Abstract
A nucleotide repeat expansion (NRE), (G4C2)n, located in a classically noncoding region of C9orf72 (C9), is the most common genetic mutation associated with ALS/FTD. There is increasing evidence that nucleic acid structures formed by the C9-NRE may both contribute to ALS/FTD, and serve as therapeutic targets, but there is limited characterization of these nucleic acid structures under physiologically and disease relevant conditions. Here we show in vitro that the C9-NRE DNA can form both parallel and antiparallel DNA G-quadruplex (GQ) topological structures and that the structural preference of these DNA GQs can be dependent on the molecular crowding conditions. Additionally, 5-methylcytosine DNA hypermethylation, which is observed in the C9-NRE locus in some patients, has minimal effects on GQ topological preferences. Finally, molecular dynamic simulations of methylated and nonmethylated GQ structures support in vitro data showing that DNA GQ structures formed by the C9-NRE DNA are stable, with structural fluctuations limited to the cytosine-containing loop regions. These findings provide new insight into the structural polymorphic preferences and stability of DNA GQs formed by the C9-NRE in both the methylated and nonmethylated states, as well as reveal important features to guide the development of upstream therapeutic approaches to potentially attenuate C9-NRE-linked diseases.
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Affiliation(s)
- Kadir A Ozcan
- Department of Neuroscience, Jefferson Weinberg ALS Center, Vickie and Jack Farber Institute for Neuroscience, Thomas Jefferson University, Philadelphia, PA, USA
| | - Layla T Ghaffari
- Department of Neuroscience, Jefferson Weinberg ALS Center, Vickie and Jack Farber Institute for Neuroscience, Thomas Jefferson University, Philadelphia, PA, USA
| | - Aaron R Haeusler
- Department of Neuroscience, Jefferson Weinberg ALS Center, Vickie and Jack Farber Institute for Neuroscience, Thomas Jefferson University, Philadelphia, PA, USA. .,Department of Neuroscience, Jefferson Weinberg ALS Center, Vickie and Jack Farber Institute for Neuroscience, Thomas Jefferson University, 900 Walnut Street, JHN suite 410, Philadelphia, PA, 19107, USA.
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6
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Kejnovská I, Stadlbauer P, Trantírek L, Renčiuk D, Gajarský M, Krafčík D, Palacký J, Bednářová K, Šponer J, Mergny JL, Vorlíčková M. G-Quadruplex Formation by DNA Sequences Deficient in Guanines: Two Tetrad Parallel Quadruplexes Do Not Fold Intramolecularly. Chemistry 2021; 27:12115-12125. [PMID: 34145655 DOI: 10.1002/chem.202100895] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Indexed: 02/05/2023]
Abstract
Guanine quadruplexes (G4s) are noncanonical forms of nucleic acids that are frequently found in genomes. The stability of G4s depends, among other factors, on the number of G-tetrads. Three- or four-tetrad G4s and antiparallel two-tetrad G4s have been characterized experimentally; however, the existence of an intramolecular (i. e., not dimeric or multimeric) two-tetrad parallel-stranded DNA G4 has never been experimentally observed. Many sequences compatible with two-tetrad G4 can be found in important genomic regions, such as promoters, for which parallel G4s predominate. Using experimental and theoretical approaches, the propensity of the model sequence AATGGGTGGGTTTGGGTGGGTAA to form an intramolecular parallel-stranded G4 upon increasing the number of GGG-to-GG substitutions has been studied. Deletion of a single G leads to the formation of intramolecular G4s with a stacked G-triad, whose topology depends on the location of the deletion. Removal of another guanine from another G-tract leads to di- or multimeric G4s. Further deletions mostly prevent the formation of any stable G4. Thus, a solitary two-tetrad parallel DNA G4 is not thermodynamically stable and requires additional interactions through capping residues. However, transiently populated metastable two-tetrad species can associate to form stable dimers, the dynamic formation of which might play additional delicate roles in gene regulation. These findings provide essential information for bioinformatics studies searching for potential G4s in genomes.
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Affiliation(s)
- Iva Kejnovská
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65, Brno, Czech Republic
| | - Petr Stadlbauer
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65, Brno, Czech Republic
| | - Lukáš Trantírek
- Central European Institute of Technology, Masaryk University, Kamenice 753/3, 625 00, Brno, Czech Republic
| | - Daniel Renčiuk
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65, Brno, Czech Republic
| | - Martin Gajarský
- Central European Institute of Technology, Masaryk University, Kamenice 753/3, 625 00, Brno, Czech Republic
| | - Daniel Krafčík
- Central European Institute of Technology, Masaryk University, Kamenice 753/3, 625 00, Brno, Czech Republic
| | - Jan Palacký
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65, Brno, Czech Republic
| | - Klára Bednářová
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65, Brno, Czech Republic
| | - Jiří Šponer
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65, Brno, Czech Republic
| | - Jean-Louis Mergny
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65, Brno, Czech Republic
| | - Michaela Vorlíčková
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65, Brno, Czech Republic
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7
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Stadlbauer P, Islam B, Otyepka M, Chen J, Monchaud D, Zhou J, Mergny JL, Šponer J. Insights into G-Quadruplex-Hemin Dynamics Using Atomistic Simulations: Implications for Reactivity and Folding. J Chem Theory Comput 2021; 17:1883-1899. [PMID: 33533244 DOI: 10.1021/acs.jctc.0c01176] [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
Guanine quadruplex nucleic acids (G4s) are involved in key biological processes such as replication or transcription. Beyond their biological relevance, G4s find applications as biotechnological tools since they readily bind hemin and enhance its peroxidase activity, creating a G4-DNAzyme. The biocatalytic properties of G4-DNAzymes have been thoroughly studied and used for biosensing purposes. Despite hundreds of applications and massive experimental efforts, the atomistic details of the reaction mechanism remain unclear. To help select between the different hypotheses currently under investigation, we use extended explicit-solvent molecular dynamics (MD) simulations to scrutinize the G4/hemin interaction. We find that besides the dominant conformation in which hemin is stacked atop the external G-quartets, hemin can also transiently bind to the loops and be brought to the external G-quartets through diverse delivery mechanisms. The simulations do not support the catalytic mechanism relying on a wobbling guanine. Similarly, the catalytic role of the iron-bound water molecule is not in line with our results; however, given the simulation limitations, this observation should be considered with some caution. The simulations rather suggest tentative mechanisms in which the external G-quartet itself could be responsible for the unique H2O2-promoted biocatalytic properties of the G4/hemin complexes. Once stacked atop a terminal G-quartet, hemin rotates about its vertical axis while readily sampling shifted geometries where the iron transiently contacts oxygen atoms of the adjacent G-quartet. This dynamics is not apparent from the ensemble-averaged structure. We also visualize transient interactions between the stacked hemin and the G4 loops. Finally, we investigated interactions between hemin and on-pathway folding intermediates of the parallel-stranded G4 fold. The simulations suggest that hemin drives the folding of parallel-stranded G4s from slip-stranded intermediates, acting as a G4 chaperone. Limitations of the MD technique are briefly discussed.
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Affiliation(s)
- Petr Stadlbauer
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic
| | - Barira Islam
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic
| | - Michal Otyepka
- 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, Palacký University, Křížkovského 8, 779 00 Olomouc, Czech Republic
| | - Jielin Chen
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - David Monchaud
- Institut de Chimie Moléculaire (ICMUB), CNRS UMR6302, UBFC, Dijon 21078, France
| | - Jun Zhou
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Jean-Louis Mergny
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic.,State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210023, China.,Laboratoire d'Optique et Biosciences, Ecole Polytechnique, CNRS, INSERM, Institut Polytechnique de Paris, 91128 Palaiseau cedex, France
| | - Jiří Šponer
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic
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8
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Balasubramanian S, Senapati S. Dynamics and Barrier of Movements of Sodium and Potassium Ions Across the Oxytricha nova G-Quadruplex Core. J Phys Chem B 2020; 124:11055-11066. [PMID: 33238706 DOI: 10.1021/acs.jpcb.0c04826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
G-quadruplexes (GQs) are highly stable noncanonical forms of nucleic acids that are present in important genomic regions. The central core of the GQ is lined up by four closely spaced carbonyl groups from the G-quartets, and the resulting electrostatic repulsion is neutralized by the coordinating cations. In spite of several reports on GQ structure and cation-GQ interactions, the atomic- to molecular-level understanding of the ion dynamics and ion exchange in the GQ core is quite poor. Here, we attempt to elucidate the mechanism of Na+ and K+ binding to the GQ core and trace the exchange of these ions with the ions in bulk by means of all-atomic molecular dynamics (MD) simulations. One of the most studied GQs, Oxytricha nova telomeric G-quadruplex (OxyGQ), is taken as the representative GQ. Subsequently, umbrella sampling MD simulations were performed to elucidate the energetics of ion translocation from one end to the other end of the GQ central core. Our study highlights the importance of ion hydration for the uptake and correct positioning of the cations in the core. The free-energy landscape of ion transport has shown favorable in-plane binding of Na+ ions with GQ quartets, which matches very well with the crystal structure. The binding of K+ ions, on the other hand, was out-of-plane and its translocation required a larger barrier to cross.
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Affiliation(s)
- Sangeetha Balasubramanian
- Department of Biotechnology, BJM School of Biosciences, Indian Institute of Technology Madras, Chennai 600 036, India
| | - Sanjib Senapati
- Department of Biotechnology, BJM School of Biosciences, Indian Institute of Technology Madras, Chennai 600 036, India
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9
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Bednářová K, Vorlíčková M, Renčiuk D. Diversity of Parallel Guanine Quadruplexes Induced by Guanine Substitutions. Int J Mol Sci 2020; 21:E6123. [PMID: 32854410 PMCID: PMC7503932 DOI: 10.3390/ijms21176123] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 08/21/2020] [Accepted: 08/22/2020] [Indexed: 01/17/2023] Open
Abstract
Recently, we reported an inhibitory effect of guanine substitutions on the conformational switch from antiparallel to parallel quadruplexes (G4) induced by dehydrating agents. As a possible cause, we proposed a difference in the sensitivity of parallel and antiparallel quadruplexes to the guanine substitutions in the resulting thermodynamic stability. Reports on the influence of guanine substitutions on the biophysical properties of intramolecular parallel quadruplexes are rare. Moreover, such reports are often complicated by the multimerisation tendencies of parallel quadruplexes. To address this incomplete knowledge, we employed circular dichroism spectroscopy (CD), both as stopped-flow-assisted fast kinetics measurements and end-point measurements, accompanied by thermodynamic analyses, based on UV absorption melting profiles, and electrophoretic methods. We showed that parallel quadruplexes are significantly more sensitive towards guanine substitutions than antiparallel ones. Furthermore, guanine-substituted variants, which in principle might correspond to native genomic sequences, distinctly differ in their biophysical properties, indicating that the four guanines in each tetrad of parallel quadruplexes are not equal. In addition, we were able to distinguish by CD an intramolecular G4 from intermolecular ones resulting from multimerisation mediated by terminal tetrad association, but not from intermolecular G4s formed due to inter-strand Hoogsteen hydrogen bond formation. In conclusion, our study indicates significant variability in parallel quadruplex structures, otherwise disregarded without detailed experimental analysis.
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Affiliation(s)
| | | | - Daniel Renčiuk
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic; (K.B.); (M.V.)
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10
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Mlýnský V, Kührová P, Kühr T, Otyepka M, Bussi G, Banáš P, Šponer J. Fine-Tuning of the AMBER RNA Force Field with a New Term Adjusting Interactions of Terminal Nucleotides. J Chem Theory Comput 2020; 16:3936-3946. [PMID: 32384244 DOI: 10.1021/acs.jctc.0c00228] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Determination of RNA structural-dynamic properties is challenging for experimental methods. Thus, atomistic molecular dynamics (MD) simulations represent a helpful technique complementary to experiments. However, contemporary MD methods still suffer from limitations of force fields (ffs), including imbalances in the nonbonded ff terms. We have recently demonstrated that some improvement of state-of-the-art AMBER RNA ff can be achieved by adding a new term for H-bonding called gHBfix, which increases tuning flexibility and reduces risk of side-effects. Still, the first gHBfix version did not fully correct simulations of short RNA tetranucleotides (TNs). TNs are key benchmark systems due to availability of unique NMR data, although giving too much weight on improving TN simulations can easily lead to overfitting to A-form RNA. Here we combine the gHBfix version with another term called tHBfix, which separately treats H-bond interactions formed by terminal nucleotides. This allows to refine simulations of RNA TNs without affecting simulations of other RNAs. The approach is in line with adopted strategy of current RNA ffs, where the terminal nucleotides possess different parameters for terminal atoms than the internal nucleotides. Combination of gHBfix with tHBfix significantly improves the behavior of RNA TNs during well-converged enhanced-sampling simulations using replica exchange with solute tempering. TNs mostly populate canonical A-form like states while spurious intercalated structures are largely suppressed. Still, simulations of r(AAAA) and r(UUUU) TNs show some residual discrepancies with primary NMR data which suggests that future tuning of some other ff terms might be useful. Nevertheless, the tHBfix has a clear potential to improve modeling of key biochemical processes, where interactions of RNA single stranded ends are involved.
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Affiliation(s)
- Vojtěch Mlýnský
- Institute of Biophysics of the Czech Academy of Sciences, Kralovopolská 135, 612 65 Brno, Czech Republic
| | - Petra Kührová
- Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University, tř. 17 listopadu 12, 771 46 Olomouc, Czech Republic
| | - Tomáš Kühr
- Department of Computer Science, Faculty of Science, Palacký University, tř. 17 listopadu 12, 771 46 Olomouc, Czech Republic
| | - Michal Otyepka
- Institute of Biophysics of the Czech Academy of Sciences, Kralovopolská 135, 612 65 Brno, Czech Republic.,Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University, tř. 17 listopadu 12, 771 46 Olomouc, 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, Kralovopolská 135, 612 65 Brno, Czech Republic.,Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University, tř. 17 listopadu 12, 771 46 Olomouc, Czech Republic
| | - Jiří Šponer
- Institute of Biophysics of the Czech Academy of Sciences, Kralovopolská 135, 612 65 Brno, Czech Republic
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