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De Rache A, Marquevielle J, Bouaziz S, Vialet B, Andreola ML, Mergny JL, Amrane S. Structure of a DNA G-quadruplex that Modulates SP1 Binding Sites Architecture in HIV-1 Promoter. J Mol Biol 2024; 436:168359. [PMID: 37952768 DOI: 10.1016/j.jmb.2023.168359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 11/02/2023] [Accepted: 11/03/2023] [Indexed: 11/14/2023]
Abstract
Nucleic acid sequences containing guanine tracts are able to form non-canonical DNA or RNA structures known as G-quadruplexes (or G4s). These structures, based on the stacking of G-tetrads, are involved in various biological processes such as gene expression regulation. Here, we investigated a G4 forming sequence, HIVpro2, derived from the HIV-1 promoter. This motif is located 60 nucleotides upstream of the proviral Transcription Starting Site (TSS) and overlaps with two SP1 transcription factor binding sites. Using NMR spectroscopy, we determined that HIVpro2 forms a hybrid type G4 structure with a core that is interrupted by a single nucleotide bulge. An additional reverse-Hoogsteen AT base pair is stacked on top of the tetrad. SP1 transcription factor is known to regulate transcription activity of many genes through the recognition of Guanine-rich duplex motifs. Here, the formation of HIVpro2 G4 may modulate SP1 binding sites architecture by competing with the formation of the canonical duplex structure. Such DNA structural switch potentially participates to the regulation of viral transcription and may also interfere with HIV-1 reactivation or viral latency.
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Affiliation(s)
- Aurore De Rache
- Université de Bordeaux, Bordeaux, France; ARNA Laboratory, INSERM U1212, CNRS UMR 5320, IECB, Bordeaux, France; Department of Chemistry, U. Namur, 61 rue de Bruxelles, B5000 Namur, Belgium
| | - Julien Marquevielle
- Université de Bordeaux, Bordeaux, France; ARNA Laboratory, INSERM U1212, CNRS UMR 5320, IECB, Bordeaux, France
| | | | - Brune Vialet
- Université de Bordeaux, Bordeaux, France; ARNA Laboratory, INSERM U1212, CNRS UMR 5320, IECB, Bordeaux, France
| | - Marie-Line Andreola
- Université de Bordeaux, Bordeaux, France; MFP Laboratory, UMR5234, CNRS, Bordeaux, France
| | - Jean-Louis Mergny
- Laboratoire d'Optique & Biosciences, École Polytechnique, CNRS, Inserm, Institut Polytechnique de Paris, 91120 Palaiseau, France
| | - Samir Amrane
- Université de Bordeaux, Bordeaux, France; ARNA Laboratory, INSERM U1212, CNRS UMR 5320, IECB, Bordeaux, France.
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2
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Sato K, Knipscheer P. G-quadruplex resolution: From molecular mechanisms to physiological relevance. DNA Repair (Amst) 2023; 130:103552. [PMID: 37572578 DOI: 10.1016/j.dnarep.2023.103552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 07/29/2023] [Accepted: 08/01/2023] [Indexed: 08/14/2023]
Abstract
Guanine-rich DNA sequences can fold into stable four-stranded structures called G-quadruplexes or G4s. Research in the past decade demonstrated that G4 structures are widespread in the genome and prevalent in regulatory regions of actively transcribed genes. The formation of G4s has been tightly linked to important biological processes including regulation of gene expression and genome maintenance. However, they can also pose a serious threat to genome integrity especially by impeding DNA replication, and G4-associated somatic mutations have been found accumulated in the cancer genomes. Specialised DNA helicases and single stranded DNA binding proteins that can resolve G4 structures play a crucial role in preventing genome instability. The large variety of G4 unfolding proteins suggest the presence of multiple G4 resolution mechanisms in cells. Recently, there has been considerable progress in our detailed understanding of how G4s are resolved, especially during DNA replication. In this review, we first discuss the current knowledge of the genomic G4 landscapes and the impact of G4 structures on DNA replication and genome integrity. We then describe the recent progress on the mechanisms that resolve G4 structures and their physiological relevance. Finally, we discuss therapeutic opportunities to target G4 structures.
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Affiliation(s)
- Koichi Sato
- Oncode Institute, Hubrecht Institute-KNAW & University Medical Center Utrecht, Utrecht, the Netherlands.
| | - Puck Knipscheer
- Oncode Institute, Hubrecht Institute-KNAW & University Medical Center Utrecht, Utrecht, the Netherlands; Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands.
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3
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Tariq N, Xu C, Wang J, Kume T, Macgregor RB. Enhancement of the thermal stability of G-quadruplex structures by urea. Biophys Chem 2023; 299:107043. [PMID: 37285661 DOI: 10.1016/j.bpc.2023.107043] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 05/12/2023] [Accepted: 05/23/2023] [Indexed: 06/09/2023]
Abstract
The solute urea has been used extensively as a denaturant in protein folding studies; double-stranded nucleic acid structures are also destabilized by urea, but comparatively less than proteins. In previous research, the solute has been shown to strongly destabilize folded G-quadruplex DNA structures. This contribution demonstrates the stabilizing effect of urea on the G-quadruplex formed by the oligodeoxyribonucleotide (ODN), G3T (d[5'-GGGTGGGTGGGTGGG-3']), and related sequences in the presence of sodium or potassium cations. Stabilization is observed up to 7 M urea, which was the highest concentration we investigated. The folded structure of G3T has three G-tetrads and three loops that consist of single thymine residues. ODNs related to G3T, in which the thymine residues in the loop are substituted by adenosine residues, also exhibit enhanced stability in the presence of molar concentrations of urea. The circular dichroism (CD) spectra of these ODNs in the presence of urea are consistent with that of a G-quadruplex. As the urea concentration increases, the spectral intensities of the peaks and troughs change, while their positions change very little. The heat-induced transition from the folded to unfolded state, Tm, was measured by monitoring the change in the UV absorption as a function of temperature. G-quadruplex structures with loops containing single bases exhibited large increases in Tm with increasing urea concentrations. These data imply that the loop region play a significant role in the thermal stability of tetra-helical DNA structures in the presence of the solute urea.
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Affiliation(s)
- Nabeel Tariq
- Graduate Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Canada
| | - Christine Xu
- Graduate Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Canada
| | - Jingtong Wang
- Graduate Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Canada
| | - Takuma Kume
- Graduate Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Canada
| | - Robert B Macgregor
- Graduate Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Canada.
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4
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DNA Base Excision Repair Intermediates Influence Duplex-Quadruplex Equilibrium. Molecules 2023; 28:molecules28030970. [PMID: 36770637 PMCID: PMC9920732 DOI: 10.3390/molecules28030970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/12/2023] [Accepted: 01/13/2023] [Indexed: 01/21/2023] Open
Abstract
Although genomic DNA is predominantly duplex under physiological conditions, particular sequence motifs can favor the formation of alternative secondary structures, including the G-quadruplex. These structures can exist within gene promoters, telomeric DNA, and regions of the genome frequently found altered in human cancers. DNA is also subject to hydrolytic and oxidative damage, and its local structure can influence the type of damage and its magnitude. Although the repair of endogenous DNA damage by the base excision repair (BER) pathway has been extensively studied in duplex DNA, substantially less is known about repair in non-duplex DNA structures. Therefore, we wanted to better understand the effect of DNA damage and repair on quadruplex structure. We first examined the effect of placing pyrimidine damage products uracil, 5-hydroxymethyluracil, the chemotherapy agent 5-fluorouracil, and an abasic site into the loop region of a 22-base telomeric repeat sequence known to form a G-quadruplex. Quadruplex formation was unaffected by these analogs. However, the activity of the BER enzymes were negatively impacted. Uracil DNA glycosylase (UDG) and single-strand selective monofunctional uracil DNA glycosylase (SMUG1) were inhibited, and apurinic/apyrimidinic endonuclease 1 (APE1) activity was completely blocked. Interestingly, when we performed studies placing DNA repair intermediates into the strand opposite the quadruplex, we found that they destabilized the duplex and promoted quadruplex formation. We propose that while duplex is the preferred configuration, there is kinetic conversion between duplex and quadruplex. This is supported by our studies using a quadruplex stabilizing molecule, pyridostatin, that is able to promote quadruplex formation starting from duplex DNA. Our results suggest how DNA damage and repair intermediates can alter duplex-quadruplex equilibrium.
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5
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Pavlova AV, Dolinnaya NG, Zvereva MI, Kubareva EA, Monakhova MV. New DNA Plasmid Model for Studying DNA Mismatch Repair Response to the G4 Structure. Int J Mol Sci 2023; 24:ijms24021061. [PMID: 36674575 PMCID: PMC9863064 DOI: 10.3390/ijms24021061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 12/27/2022] [Accepted: 12/31/2022] [Indexed: 01/08/2023] Open
Abstract
G-quadruplexes (G4s), the most widely studied alternative DNA structures, are implicated in the regulation of the key cellular processes. In recent years, their involvement in DNA repair machinery has become the subject of intense research. Here, we evaluated the effect of G4 on the prokaryotic DNA mismatch repair (MMR) pathway from two bacterial sources with different mismatch repair mechanisms. The G4 folding, which competes with the maintenance of double-stranded DNA, is known to be controlled by numerous opposing factors. To overcome the kinetic barrier of G4 formation, we stabilized a parallel G4 formed by the d(GGGT)4 sequence in a DNA plasmid lacking a fragment complementary to the G4 motif. Unlike commonly used isolated G4 structures, our plasmid with an embedded stable G4 structure contained elements, such as a MutH cleavage site, required to initiate the repair process. G4 formation in the designed construct was confirmed by Taq polymerase stop assay and dimethyl sulfate probing. The G4-carrying plasmid, together with control ones (lacking a looped area or containing unstructured d(GT)8 insert instead of the G4 motif), were used as new type models to answer the question of whether G4 formation interferes with DNA cleavage as a basic function of MMR.
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Affiliation(s)
- Anzhela V. Pavlova
- Department of Chemistry, Lomonosov Moscow State University, Leninskye Gory 1, Moscow 119991, Russia
| | - Nina G. Dolinnaya
- Department of Chemistry, Lomonosov Moscow State University, Leninskye Gory 1, Moscow 119991, Russia
| | - Maria I. Zvereva
- Department of Chemistry, Lomonosov Moscow State University, Leninskye Gory 1, Moscow 119991, Russia
| | - Elena A. Kubareva
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskye Gory 1, Moscow 119991, Russia
- Correspondence: ; Tel.: +7-(495)-939-54-11
| | - Mayya V. Monakhova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskye Gory 1, Moscow 119991, Russia
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6
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Tsao L, Shepardson-Fungairiño S, Murayama H, Cecere A, Wren E, Núñez M. Assessing the Potential for DNA Quadruplex Formation in the Predatory Bacterium Bdellovibrio bacteriovorus. Biochemistry 2022; 61:2073-2087. [PMID: 36193632 PMCID: PMC9536305 DOI: 10.1021/acs.biochem.2c00443] [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: 07/29/2022] [Revised: 08/25/2022] [Indexed: 11/29/2022]
Abstract
During its life cycle, the predatory bacterium Bdellovibrio bacteriovorus switches between an attack and a growth phase, each of which is characterized by a distinct pattern of gene expression. Twenty-one potential G-quadruplex-forming sequences (PQFS) have been identified in the Bdellovibrio genome. These G-rich sequences are prevalent within open reading frames and nearly evenly distributed between the template and the coding strand, suggesting that they could play a role in gene expression and life cycle switching. Published transcriptomic data show that the genes nearest these sequences are not (de)activated together during the same phases of the life cycle. We explored the biophysical properties of three identified PQFS using circular dichroism (CD) spectroscopy and gel electrophoresis and demonstrated that all three sequences fold into stable unimolecular quadruplexes with distinct topologies. In the presence of their complementary strands, each forms an equilibrium mixture of duplex and quadruplex in which quadruplex formation is favored at higher temperatures. Once the quadruplexes are folded, they are slow to form a duplex when the complementary strand is added, with one sequence requiring the equivalent of many Bdellovibrio lifetimes to do so. Using a variety of cosolutes, we showed that molecular crowding mimicking cellular conditions stabilizes the quadruplex structures and induces structural transitions to the parallel topology regardless of the original topology. Taken together, these experiments suggest that Bdellovibrio PQFS are capable of forming quadruplexes in vivo and thereby playing a role in gene expression.
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Affiliation(s)
- Lucille
H. Tsao
- Department of Chemistry and
Program in Biochemistry, Wellesley College, Wellesley, Massachusetts 02481, United States
| | - Sally Shepardson-Fungairiño
- Department of Chemistry and
Program in Biochemistry, Wellesley College, Wellesley, Massachusetts 02481, United States
| | - Hikari Murayama
- Department of Chemistry and
Program in Biochemistry, Wellesley College, Wellesley, Massachusetts 02481, United States
| | - Amelia Cecere
- Department of Chemistry and
Program in Biochemistry, Wellesley College, Wellesley, Massachusetts 02481, United States
| | - Elizabeth Wren
- Department of Chemistry and
Program in Biochemistry, Wellesley College, Wellesley, Massachusetts 02481, United States
| | - Megan Núñez
- Department of Chemistry and
Program in Biochemistry, Wellesley College, Wellesley, Massachusetts 02481, United States
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7
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Cueny RR, McMillan SD, Keck JL. G-quadruplexes in bacteria: insights into the regulatory roles and interacting proteins of non-canonical nucleic acid structures. Crit Rev Biochem Mol Biol 2022; 57:539-561. [PMID: 36999585 PMCID: PMC10336854 DOI: 10.1080/10409238.2023.2181310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 12/13/2022] [Accepted: 02/13/2023] [Indexed: 04/01/2023]
Abstract
G-quadruplexes (G4s) are highly stable, non-canonical DNA or RNA structures that can form in guanine-rich stretches of nucleic acids. G4-forming sequences have been found in all domains of life, and proteins that bind and/or resolve G4s have been discovered in both bacterial and eukaryotic organisms. G4s regulate a variety of cellular processes through inhibitory or stimulatory roles that depend upon their positions within genomes or transcripts. These include potential roles as impediments to genome replication, transcription, and translation or, in other contexts, as activators of genome stability, transcription, and recombination. This duality suggests that G4 sequences can aid cellular processes but that their presence can also be problematic. Despite their documented importance in bacterial species, G4s remain understudied in bacteria relative to eukaryotes. In this review, we highlight the roles of bacterial G4s by discussing their prevalence in bacterial genomes, the proteins that bind and unwind G4s in bacteria, and the processes regulated by bacterial G4s. We identify limitations in our current understanding of the functions of G4s in bacteria and describe new avenues for studying these remarkable nucleic acid structures.
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Affiliation(s)
- Rachel R. Cueny
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, 53706, USA
| | - Sarah D. McMillan
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, 53706, USA
| | - James L. Keck
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, 53706, USA
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8
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Göç YB, Poziemski J, Smolińska W, Suwała D, Wieczorek G, Niedzialek D. Tracking Topological and Electronic Effects on the Folding and Stability of Guanine-Deficient RNA G-Quadruplexes, Engineered with a New Computational Tool for De Novo Quadruplex Folding. Int J Mol Sci 2022; 23:ijms231910990. [PMID: 36232294 PMCID: PMC9570295 DOI: 10.3390/ijms231910990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 09/09/2022] [Accepted: 09/13/2022] [Indexed: 11/16/2022] Open
Abstract
The initial aim of this work was to elucidate the mutual influence of different single-stranded segments (loops and caps) on the thermodynamic stability of RNA G-quadruplexes. To this end, we used a new NAB-GQ-builder software program, to construct dozens of two-tetrad G-quadruplex topologies, based on a designed library of sequences. Then, to probe the sequence–morphology–stability relationships of the designed topologies, we performed molecular dynamics simulations. Their results provide guidance for the design of G-quadruplexes with balanced structures, and in turn programmable physicochemical properties for applications as biomaterials. Moreover, by comparative examinations of the single-stranded segments of three oncogene promoter G-quadruplexes, we assess their druggability potential for future therapeutic strategies. Finally, on the basis of a thorough analysis at the quantum mechanical level of theory on a series of guanine assemblies, we demonstrate how a valence tautomerism, triggered by a coordination of cations, initiates the process of G-quadruplex folding, and we propose a sequential folding mechanism, otherwise dictated by the cancellation of the dipole moments on guanines.
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Affiliation(s)
- Yavuz Burak Göç
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland or
- Faculty of Chemistry, Biological & Chemical Research Center, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland
| | - Jakub Poziemski
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland or
| | - Weronika Smolińska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland or
- Faculty of Chemical and Process Engineering, Warsaw University of Technology, Waryńskiego 1, 00-645 Warsaw, Poland
| | - Dominik Suwała
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland or
- Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
| | - Grzegorz Wieczorek
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland or
- Molecure SA, Żwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Dorota Niedzialek
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland or
- Correspondence:
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9
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Liu L, Zhu L, Tong H, Su C, Wells JW, Chalikian TV. Distribution of Conformational States Adopted by DNA from the Promoter Regions of the VEGF and Bcl-2 Oncogenes. J Phys Chem B 2022; 126:6654-6670. [PMID: 36001297 DOI: 10.1021/acs.jpcb.2c04304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We employed a previously described procedure, based on circular dichroism (CD) spectroscopy, to quantify the distribution of conformational states adopted by equimolar mixtures of complementary G-rich and C-rich DNA strands from the promoter regions of the VEGF and Bcl-2 oncogenes. Spectra were recorded at different pHs, concentrations of KCl, and temperatures. The temperature dependences of the fractional populations of the duplex, G-quadruplex, i-motif, and coiled conformations of each promoter were then analyzed within the framework of a thermodynamic model to obtain the enthalpy and melting temperature of each folded-to-unfolded transition involved in the equilibrium. A comparison of the conformational data on the VEGF and Bcl-2 DNA with similar results on the c-MYC DNA, which we reported previously, reveals that the distribution of conformational states depends on the specific DNA sequence and is modulated by environmental factors. Under the physiological conditions of room temperature, neutral pH, and elevated concentrations of potassium ions, the duplex conformation coexists with the G-quadruplex conformation in proportions that depend on the sequence. This observed conformational diversity has biological implications, and it further supports our previously proposed thermodynamic hypothesis of gene regulation. In that hypothesis, a specific distribution of duplex and tetraplex conformations in a promoter region is fine-tuned to maintain the healthy level of gene expression. Any deviation from a healthy distribution of conformational states may result in pathology stemming from up- or downregulation of the gene.
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Affiliation(s)
- Lutan Liu
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
| | - Legeng Zhu
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
| | - Haoyuan Tong
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
| | - Chongyu Su
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
| | - James W Wells
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
| | - Tigran V Chalikian
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
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Wang X, Zhang M, Xiong XQ, Yang H, Wang P, Zhang K, Awadasseid A, Narva S, Wu YL, Zhang W. Design, synthesis and bioactivity of novel naphthalimide-benzotriazole conjugates against A549 cells via targeting BCL2 G-quadruplex and inducing autophagy. Life Sci 2022; 302:120651. [PMID: 35597548 DOI: 10.1016/j.lfs.2022.120651] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Revised: 05/11/2022] [Accepted: 05/16/2022] [Indexed: 12/24/2022]
Abstract
AIMS In this study, a series of novel naphthalimide-benzotriazole conjugates (1a-3c) based on 1, 8-naphthalimide as a core skeleton, aiming at G-quadruplexes, were designed and synthesized, and their anti-cancer activity and mechanism were studied. MATERIALS AND METHODS Using the CCK-8 assay, FRET melting, EMSA, CD, and molecular docking, intracellular assays, western blotting, immunofluorescence, and flow cytometry. KEY FINDINGS By the CCK-8 assay, it was found that the compound, 2-(3-(piperazin-1-yl)propyl)-6-(1H-benzo [d][1,2,3]triazol-1-yl)-1H-benzo[de]isoquinoline-1,3(2H)-dione (3a), has better activity against A549 cells. Through extracellular assays, including FRET melting, EMSA, CD, and molecular docking, results showed that 3a selectively interacted with BCL2 G-quadruplex(es). Further studies by intracellular assays, including western blotting, immunofluorescence, flow cytometry, etc., verified that 3a mediated the death of A549 cells by two pathways: inhibition of the expression of the BCL2 gene, causing tumor cell apoptosis, and promotion of genetic instability, causing autophagy. This study suggests that the type of compounds, in particular, 3a, may be a potential molecule to explore for BCL2 G-quadruplex-targeted drugs against lung cancer. SIGNIFICANCE Our findings demonstrate that compound 3a as a BCL2 G-quadruplex ligand induces DNA damage, autophagy, and apoptosis in A549 cells. This study provides us with a type of lead compound as an anti-tumor drug.
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Affiliation(s)
- Xiao Wang
- Lab of Chemical Biology and Molecular Drug Design, College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, 310014, China; Institute of Drug Development & Chemical Biology, Zhejiang University of Technology, Hangzhou, 310014, China
| | - Mi Zhang
- Lab of Chemical Biology and Molecular Drug Design, College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, 310014, China; Institute of Drug Development & Chemical Biology, Zhejiang University of Technology, Hangzhou, 310014, China
| | - Xu-Qiong Xiong
- Lab of Chemical Biology and Molecular Drug Design, College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, 310014, China; Institute of Drug Development & Chemical Biology, Zhejiang University of Technology, Hangzhou, 310014, China.
| | - Hao Yang
- Lab of Chemical Biology and Molecular Drug Design, College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, 310014, China; Institute of Drug Development & Chemical Biology, Zhejiang University of Technology, Hangzhou, 310014, China
| | - Panpan Wang
- Lab of Chemical Biology and Molecular Drug Design, College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, 310014, China; Institute of Drug Development & Chemical Biology, Zhejiang University of Technology, Hangzhou, 310014, China
| | - Koutian Zhang
- Zhejiang Jianing Pharmaceutical Technology Co., Ltd, Hangzhou, 310051, China
| | - Annoor Awadasseid
- Lab of Chemical Biology and Molecular Drug Design, College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, 310014, China; Institute of Drug Development & Chemical Biology, Zhejiang University of Technology, Hangzhou, 310014, China
| | - Suresh Narva
- Lab of Chemical Biology and Molecular Drug Design, College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, 310014, China; Institute of Drug Development & Chemical Biology, Zhejiang University of Technology, Hangzhou, 310014, China
| | - Yan-Ling Wu
- Lab of Molecular Immunology, Virus Inspection Department, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, 310051, China.
| | - Wen Zhang
- Lab of Chemical Biology and Molecular Drug Design, College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, 310014, China; Institute of Drug Development & Chemical Biology, Zhejiang University of Technology, Hangzhou, 310014, China.
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11
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Molnár OR, Végh A, Somkuti J, Smeller L. Characterization of a G-quadruplex from hepatitis B virus and its stabilization by binding TMPyP4, BRACO19 and PhenDC3. Sci Rep 2021; 11:23243. [PMID: 34853392 PMCID: PMC8636512 DOI: 10.1038/s41598-021-02689-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Accepted: 11/12/2021] [Indexed: 12/22/2022] Open
Abstract
Specific guanine rich nucleic acid sequences can form non-canonical structures, like the four stranded G-quadruplex (GQ). We studied the GQ-forming sequence (named HepB) found in the genome of the hepatitis B virus. Fluorescence-, infrared- and CD-spectroscopy were used. HepB shows a hybrid form in presence of K+, but Na+, Li+, and Rb+ induce parallel structure. Higher concentrations of metal ions increase the unfolding temperature, which was explained by a short thermodynamic calculation. Temperature stability of the GQ structure was determined for all these ions. Na+ has stronger stabilizing effect on HepB than K+, which is highly unusual. The transition temperatures were 56.6, 53.8, 58.5 and 54.4 °C for Na+, K+, Li+, and Rb+ respectively. Binding constants for Na+ and K+ were 10.2 mM and 7.1 mM respectively. Study of three ligands designed in cancer research for GQ targeting (TMPyP4, BRACO19 and PhenDC3) showed unequivocally their binding to HepB. Binding was proven by the increased stability of the bound form. The stabilization was higher than 20 °C for TMPyP4 and PhenDC3, while it was considerably lower for BRACO19. These results might have medical importance in the fight against the hepatitis B virus.
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Affiliation(s)
- Orsolya Réka Molnár
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, 1094, Hungary
| | - András Végh
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, 1094, Hungary.,Department of Ophthalmology, Semmelweis University, Budapest, 1085, Hungary
| | - Judit Somkuti
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, 1094, Hungary
| | - László Smeller
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, 1094, Hungary.
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12
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Liu YC, Yang DY, Sheu SY. Insights into the free energy landscape and salt-controlled mechanism of the conformational conversions between human telomeric G-quadruplex structures. Int J Biol Macromol 2021; 191:230-242. [PMID: 34536474 DOI: 10.1016/j.ijbiomac.2021.09.057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 08/23/2021] [Accepted: 09/10/2021] [Indexed: 12/16/2022]
Abstract
G-quadruplexes have become attractive drug targets in cancer therapy. However, due to the polymorphism of G-quadruplex structures, it is difficult to experimentally verify the relevant structures of multiple intermediates and transition states in dynamic equilibrium. Hence, understanding the mechanism by which structural conversions of G-quadruplexes occur is still challenging. We conducted targeted molecular dynamics simulation with umbrella sampling to investigate how salt affects the conformational conversion of human telomeric G-quadruplex. Our results explore a unique view into the structures and energy barrier of the intermediates and transition states in the interconversion process. The pathway of G-quadruplex conformational interconversion was mapped out by a free energy landscape, consisting of branched parallel pathways with multiple energy basins. We propose a salt-controlled mechanism that as the salt concentration increases, the conformational conversion mechanism switches from multi-pathway folding to sequential folding pathways. The hybrid-I and hybrid-II structures are intermediates in the basket-propeller transformation. In high-salt solutions, the conformational conversion upon K+ binding is more feasible than upon Na+ binding. The free energy barrier for conformational conversions ranges from 1.6 to 4.6 kcal/mol. Our work will be beneficial in developing anticancer agents.
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Affiliation(s)
- Yu-Cheng Liu
- Institute of Biomedical Informatics, National Yang Ming Chiao Tung University, Taipei 112, Taiwan
| | - Dah-Yen Yang
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan.
| | - Sheh-Yi Sheu
- Institute of Biomedical Informatics, National Yang Ming Chiao Tung University, Taipei 112, Taiwan; Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei 112, Taiwan.
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13
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Grün JT, Schwalbe H. Folding dynamics of polymorphic G-quadruplex structures. Biopolymers 2021; 113:e23477. [PMID: 34664713 DOI: 10.1002/bip.23477] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 09/30/2021] [Accepted: 09/30/2021] [Indexed: 12/14/2022]
Abstract
G-quadruplexes (G4), found in numerous places within the human genome, are involved in essential processes of cell regulation. Chromosomal DNA G4s are involved for example, in replication and transcription as first steps of gene expression. Hence, they influence a plethora of downstream processes. G4s possess an intricate structure that differs from canonical B-form DNA. Identical DNA G4 sequences can adopt multiple long-lived conformations, a phenomenon known as G4 polymorphism. A detailed understanding of the molecular mechanisms that drive G4 folding is essential to understand their ambivalent regulatory roles. Disentangling the inherent dynamic and polymorphic nature of G4 structures thus is key to unravel their biological functions and make them amenable as molecular targets in novel therapeutic approaches. We here review recent experimental approaches to monitor G4 folding and discuss structural aspects for possible folding pathways. Substantial progress in the understanding of G4 folding within the recent years now allows drawing comprehensive models of the complex folding energy landscape of G4s that we herein evaluate based on computational and experimental evidence.
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Affiliation(s)
- J Tassilo Grün
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe-University, Frankfurt/M, Germany.,Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Frankfurt/M, Germany
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14
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Miglietta G, Russo M, Capranico G. G-quadruplex-R-loop interactions and the mechanism of anticancer G-quadruplex binders. Nucleic Acids Res 2020; 48:11942-11957. [PMID: 33137181 PMCID: PMC7708042 DOI: 10.1093/nar/gkaa944] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 10/05/2020] [Accepted: 10/08/2020] [Indexed: 12/17/2022] Open
Abstract
Genomic DNA and cellular RNAs can form a variety of non-B secondary structures, including G-quadruplex (G4) and R-loops. G4s are constituted by stacked guanine tetrads held together by Hoogsteen hydrogen bonds and can form at key regulatory sites of eukaryote genomes and transcripts, including gene promoters, untranslated exon regions and telomeres. R-loops are 3-stranded structures wherein the two strands of a DNA duplex are melted and one of them is annealed to an RNA. Specific G4 binders are intensively investigated to discover new effective anticancer drugs based on a common rationale, i.e.: the selective inhibition of oncogene expression or specific impairment of telomere maintenance. However, despite the high number of known G4 binders, such a selective molecular activity has not been fully established and several published data point to a different mode of action. We will review published data that address the close structural interplay between G4s and R-loops in vitro and in vivo, and how these interactions can have functional consequences in relation to G4 binder activity. We propose that R-loops can play a previously-underestimated role in G4 binder action, in relation to DNA damage induction, telomere maintenance, genome and epigenome instability and alterations of gene expression programs.
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Affiliation(s)
- Giulia Miglietta
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum University of Bologna, via Selmi 3, 40126 Bologna, Italy
| | - Marco Russo
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum University of Bologna, via Selmi 3, 40126 Bologna, Italy
| | - Giovanni Capranico
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum University of Bologna, via Selmi 3, 40126 Bologna, Italy
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15
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Responses of DNA Mismatch Repair Proteins to a Stable G-Quadruplex Embedded into a DNA Duplex Structure. Int J Mol Sci 2020; 21:ijms21228773. [PMID: 33233554 PMCID: PMC7699706 DOI: 10.3390/ijms21228773] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 11/16/2020] [Accepted: 11/18/2020] [Indexed: 12/26/2022] Open
Abstract
DNA mismatch repair (MMR) plays a crucial role in the maintenance of genomic stability. The main MMR protein, MutS, was recently shown to recognize the G-quadruplex (G4) DNA structures, which, along with regulatory functions, have a negative impact on genome integrity. Here, we studied the effect of G4 on the DNA-binding activity of MutS from Rhodobacter sphaeroides (methyl-independent MMR) in comparison with MutS from Escherichia coli (methyl-directed MMR) and evaluated the influence of a G4 on the functioning of other proteins involved in the initial steps of MMR. For this purpose, a new DNA construct was designed containing a biologically relevant intramolecular stable G4 structure flanked by double-stranded regions with the set of DNA sites required for MMR initiation. The secondary structure of this model was examined using NMR spectroscopy, chemical probing, fluorescent indicators, circular dichroism, and UV spectroscopy. The results unambiguously showed that the d(GGGT)4 motif, when embedded in a double-stranded context, adopts a G4 structure of a parallel topology. Despite strong binding affinities of MutS and MutL for a G4, the latter is not recognized by E. coli MMR as a signal for repair, but does not prevent MMR processing when a G4 and G/T mismatch are in close proximity.
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16
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Brázda V, Luo Y, Bartas M, Kaura P, Porubiaková O, Šťastný J, Pečinka P, Verga D, Da Cunha V, Takahashi TS, Forterre P, Myllykallio H, Fojta M, Mergny JL. G-Quadruplexes in the Archaea Domain. Biomolecules 2020; 10:biom10091349. [PMID: 32967357 PMCID: PMC7565180 DOI: 10.3390/biom10091349] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 09/16/2020] [Accepted: 09/18/2020] [Indexed: 11/26/2022] Open
Abstract
The importance of unusual DNA structures in the regulation of basic cellular processes is an emerging field of research. Amongst local non-B DNA structures, G-quadruplexes (G4s) have gained in popularity during the last decade, and their presence and functional relevance at the DNA and RNA level has been demonstrated in a number of viral, bacterial, and eukaryotic genomes, including humans. Here, we performed the first systematic search of G4-forming sequences in all archaeal genomes available in the NCBI database. In this article, we investigate the presence and locations of G-quadruplex forming sequences using the G4Hunter algorithm. G-quadruplex-prone sequences were identified in all archaeal species, with highly significant differences in frequency, from 0.037 to 15.31 potential quadruplex sequences per kb. While G4 forming sequences were extremely abundant in Hadesarchaea archeon (strikingly, more than 50% of the Hadesarchaea archaeon isolate WYZ-LMO6 genome is a potential part of a G4-motif), they were very rare in the Parvarchaeota phylum. The presence of G-quadruplex forming sequences does not follow a random distribution with an over-representation in non-coding RNA, suggesting possible roles for ncRNA regulation. These data illustrate the unique and non-random localization of G-quadruplexes in Archaea.
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Affiliation(s)
- Václav Brázda
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic
| | - Yu Luo
- Institut Curie, CNRS UMR9187, INSERM U1196, Universite Paris Saclay, 91400 Orsay, France
| | - Martin Bartas
- Department of Biology and Ecology/Institute of Environmental Technologies, Faculty of Science, University of Ostrava, 710 00 Ostrava, Czech Republic
| | - Patrik Kaura
- Faculty of Mechanical Engineering, Brno University of Technology, Technicka 2896/2, 616 69 Brno, Czech Republic
| | - Otilia Porubiaková
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic
- Faculty of Chemistry, Brno University of Technology, Purkyňova 464/118, 612 00 Brno, Czech Republic
| | - Jiří Šťastný
- Faculty of Mechanical Engineering, Brno University of Technology, Technicka 2896/2, 616 69 Brno, Czech Republic
- Mendel University in Brno, Zemědělská 1, 613 00 Brno, Czech Republic
| | - Petr Pečinka
- Department of Biology and Ecology/Institute of Environmental Technologies, Faculty of Science, University of Ostrava, 710 00 Ostrava, Czech Republic
| | - Daniela Verga
- Institut Curie, CNRS UMR9187, INSERM U1196, Universite Paris Saclay, 91400 Orsay, France
| | - Violette Da Cunha
- Institut de Biologie Intégrative de la Cellule (I2BC), CNRS, Université Paris-Saclay, CEDEX, 91198 Gif-sur-Yvette, France
| | - Tomio S Takahashi
- Institut de Biologie Intégrative de la Cellule (I2BC), CNRS, Université Paris-Saclay, CEDEX, 91198 Gif-sur-Yvette, France
| | - Patrick Forterre
- Institut de Biologie Intégrative de la Cellule (I2BC), CNRS, Université Paris-Saclay, CEDEX, 91198 Gif-sur-Yvette, France
| | - Hannu Myllykallio
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, CNRS, INSERM, Institut Polytechnique de Paris, 91128 Palaiseau, France
| | - Miroslav Fojta
- 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
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, CNRS, INSERM, Institut Polytechnique de Paris, 91128 Palaiseau, France
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17
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Chalikian TV, Liu L, Macgregor RB. Duplex-tetraplex equilibria in guanine- and cytosine-rich DNA. Biophys Chem 2020; 267:106473. [PMID: 33031980 DOI: 10.1016/j.bpc.2020.106473] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 09/03/2020] [Indexed: 02/07/2023]
Abstract
Noncanonical four-stranded DNA structures, including G-quadruplexes and i-motifs, have been discovered in the cell and are implicated in a variety of genomic regulatory functions. The tendency of a specific guanine- and cytosine-rich region of genomic DNA to adopt a four-stranded conformation depends on its ability to overcome the constraints of duplex base-pairing by undergoing consecutive duplex-to-coil and coil-to-tetraplex transitions. The latter ability is determined by the balance between the free energies of participating ordered and disordered structures. In this review, we present an overview of the literature on the stability of G-quadruplex and i-motif structures and discuss the extent of duplex-tetraplex competition as a function of the sequence context of the DNA and environmental conditions including temperature, pH, salt, molecular crowding, and the presence of G-quadruplex-binding ligands. We outline how the results of in vitro studies can be expanded to understanding duplex-tetraplex equilibria in vivo.
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Affiliation(s)
- Tigran V Chalikian
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada.
| | - Lutan Liu
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
| | - Robert B Macgregor
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
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18
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Inhibition of Influenza A virus propagation by benzoselenoxanthenes stabilizing TMPRSS2 Gene G-quadruplex and hence down-regulating TMPRSS2 expression. Sci Rep 2020; 10:7635. [PMID: 32376987 PMCID: PMC7203196 DOI: 10.1038/s41598-020-64368-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 04/09/2020] [Indexed: 01/14/2023] Open
Abstract
Proteolytic cleavage of influenza A virus (IAV) hemagglutinin by host proteases is crucial for virus infectivity and spread. The transmembrane serine protease TMPRSS2 was previously identified as the essential protease that can cleave hemagglutinin of many subtypes of influenza virus and spike protein of coronavirus. Herein, we found that a guanine rich tract, capable of forming intramolecular G-quadruplex in the presence of potassium ions, in the promoter region of human TMPRSS2 gene was quite important for gene transcriptional activity, hence affecting its function. Furthermore, 7 new synthesized benzoselenoxanthene analogues were found to enable stabilizing such G-quadruplex. More importantly, compounds can down-regulate TMPRSS2 gene expression, especially endogenous TMPRSS2 protein levels, and consequently suppress influenza A virus propagation in vitro. Our results provide a new strategy for anti-influenza A virus infection by small molecules targeting the TMPRSS2 gene G-quadruplex and thus inhibiting TMPRSS2 expression, which is valuable for developing small molecule drugs against influenza A virus and also may be a potential candidate as anti- SARS-CoV-2 (Severe Acute Respiratory Syndrome CoV 2) lead molecules.
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19
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Abstract
Catalytic DNAs (DNAzymes) with peroxidase-like activity have great potential in bioanalytical chemistry [1], owing to numerous advantages that DNA enzymes offer over conventional protein enzymes, including structural simplicity, low cost, thermal stability, and straightforward handling and preparation. Maximizing the efficiency of the peroxidase activity of such DNAzymes is a subject in need of review. In this chapter, we discuss the optimal experimental conditions for the peroxidase activity of these DNAzymes and describe general procedures for their utilization.
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20
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Liu L, Ma C, Wells JW, Chalikian TV. Conformational Preferences of DNA Strands from the Promoter Region of the c-MYC Oncogene. J Phys Chem B 2020; 124:751-762. [PMID: 31923361 DOI: 10.1021/acs.jpcb.9b10518] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We characterized the conformational preferences of DNA in an equimolar mixture of complementary G-rich and C-rich strands from the promoter region of the c-MYC oncogene. Our CD-based approach presupposes that the CD spectrum of such a mixture is the spectral sum of the constituent duplex, G-quadruplex, i-motif, and coiled conformations. Spectra were acquired over a range of temperatures at different pHs and concentrations of KCl. Each spectrum was unmixed in terms of the predetermined spectra of the constituent conformational states to obtain the corresponding weighting factors for their fractional contributions to the total population of DNA. The temperature dependences of those contributions then were analyzed in concert according to a model based on a thermodynamic representation of the underlying equilibria. Fitted estimates of the melting enthalpy and temperature obtained for the duplex, G-quadruplex, and i-motif imply that the driving force behind dissociation of the duplex and the concomitant formation of tetrahelical structures is the folding of the G-strand into the G-quadruplex. The liberated C-strand adopts the i-motif conformation at acidic pH and exists in the coiled state at neutral pH. The i-motif alone cannot induce dissociation of the duplex even at pH 5.0, at which it is most stable. Under the physiological conditions of neutral pH, elevated potassium, and room temperature, the duplex and G-quadruplex conformations coexist with the C-strand in the coiled state. Taken together, our results suggest a novel, thermodynamically controlled mechanism for the regulation of gene expression.
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Affiliation(s)
- Lutan Liu
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy , University of Toronto , 144 College Street , Toronto , Ontario M5S 3M2 , Canada
| | - Congshan Ma
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy , University of Toronto , 144 College Street , Toronto , Ontario M5S 3M2 , Canada
| | - James W Wells
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy , University of Toronto , 144 College Street , Toronto , Ontario M5S 3M2 , Canada
| | - Tigran V Chalikian
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy , University of Toronto , 144 College Street , Toronto , Ontario M5S 3M2 , Canada
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21
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Chasing Particularities of Guanine- and Cytosine-Rich DNA Strands. Molecules 2020; 25:molecules25030434. [PMID: 31972988 PMCID: PMC7037129 DOI: 10.3390/molecules25030434] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 01/17/2020] [Accepted: 01/20/2020] [Indexed: 01/17/2023] Open
Abstract
By substitution of natural nucleotides by their abasic analogs (i.e., 1',2'-dideoxyribose phosphate residue) at critically chosen positions within 27-bp DNA constructs originating from the first intron of N-myc gene, we hindered hybridization within the guanine- and cytosine-rich central region and followed formation of non-canonical structures. The impeded hybridization between the complementary strands leads to time-dependent structural transformations of guanine-rich strand that are herein characterized with the use of solution-state NMR, CD spectroscopy, and native polyacrylamide gel electrophoresis. Moreover, the DNA structural changes involve transformation of intra- into inter-molecular G-quadruplex structures that are thermodynamically favored. Intriguingly, the transition occurs in the presence of complementary cytosine-rich strands highlighting the inability of Watson-Crick base-pairing to preclude the transformation between G-quadruplex structures that occurs via intertwining mechanism and corroborates a role of G-quadruplex structures in DNA recombination processes.
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22
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Takahashi S, Sugimoto N. Stability prediction of canonical and non-canonical structures of nucleic acids in various molecular environments and cells. Chem Soc Rev 2020; 49:8439-8468. [DOI: 10.1039/d0cs00594k] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This review provides the biophysicochemical background and recent advances in stability prediction of canonical and non-canonical structures of nucleic acids in various molecular environments and cells.
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Affiliation(s)
- Shuntaro Takahashi
- Frontier Institute for Biomolecular Engineering Research (FIBER)
- Konan University
- Kobe
- Japan
| | - Naoki Sugimoto
- Frontier Institute for Biomolecular Engineering Research (FIBER)
- Konan University
- Kobe
- Japan
- Graduate School of Frontiers of Innovative Research in Science and Technology (FIRST)
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23
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Kolesnikova S, Curtis EA. Structure and Function of Multimeric G-Quadruplexes. Molecules 2019; 24:molecules24173074. [PMID: 31450559 PMCID: PMC6749722 DOI: 10.3390/molecules24173074] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 08/21/2019] [Accepted: 08/22/2019] [Indexed: 11/16/2022] Open
Abstract
G-quadruplexes are noncanonical nucleic acid structures formed from stacked guanine tetrads. They are frequently used as building blocks and functional elements in fields such as synthetic biology and also thought to play widespread biological roles. G-quadruplexes are often studied as monomers, but can also form a variety of higher-order structures. This increases the structural and functional diversity of G-quadruplexes, and recent evidence suggests that it could also be biologically important. In this review, we describe the types of multimeric topologies adopted by G-quadruplexes and highlight what is known about their sequence requirements. We also summarize the limited information available about potential biological roles of multimeric G-quadruplexes and suggest new approaches that could facilitate future studies of these structures.
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Affiliation(s)
- Sofia Kolesnikova
- The Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 166 10 Prague, Czech Republic
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, 166 28 Prague, Czech Republic
| | - Edward A Curtis
- The Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 166 10 Prague, Czech Republic.
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24
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Somkuti J, Adányi M, Smeller L. Self-crowding influences the temperature - pressure stability of the human telomere G-quadruplex. Biophys Chem 2019; 254:106248. [PMID: 31470349 DOI: 10.1016/j.bpc.2019.106248] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 08/07/2019] [Accepted: 08/09/2019] [Indexed: 01/22/2023]
Abstract
We measured the effect of crowded environment on G-quadruplex structures, formed by guanine rich DNA sequences. Fluorescence and infrared spectroscopy were used to determine the temperature stability of G-quadruplex structure formed by the human telomere sequence. We determined the T-p phase diagram of Htel aptamer up to 1 GPa at different self-crowding conditions. The unfolding volume change was determined from the pressure induced shift of the unfolding temperature of the quadruplex form. The unfolding volume change decreased in magnitude, and even its sign changed from negative (-19 ml/mol) to positive (7 ml/mol) under self-crowded conditions. The possible explanations are the appearance of the parallel GQ structure at high concentration or the fact that the volume decrease caused by the released central K+ ion during the unfolding is less significant in crowded environment.
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Affiliation(s)
- J Somkuti
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
| | - M Adányi
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
| | - L Smeller
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary.
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25
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Asamitsu S, Obata S, Yu Z, Bando T, Sugiyama H. Recent Progress of Targeted G-Quadruplex-Preferred Ligands Toward Cancer Therapy. Molecules 2019; 24:E429. [PMID: 30682877 PMCID: PMC6384606 DOI: 10.3390/molecules24030429] [Citation(s) in RCA: 192] [Impact Index Per Article: 38.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 01/22/2019] [Accepted: 01/23/2019] [Indexed: 02/07/2023] Open
Abstract
A G-quadruplex (G4) is a well-known nucleic acid secondary structure comprising guanine-rich sequences, and has profound implications for various pharmacological and biological events, including cancers. Therefore, ligands interacting with G4s have attracted great attention as potential anticancer therapies or in molecular probe applications. To date, a large variety of DNA/RNA G4 ligands have been developed by a number of laboratories. As protein-targeting drugs face similar situations, G-quadruplex-interacting drugs displayed low selectivity to the targeted G-quadruplex structure. This low selectivity could cause unexpected effects that are usually reasons to halt the drug development process. In this review, we address the recent research on synthetic G4 DNA-interacting ligands that allow targeting of selected G4s as an approach toward the discovery of highly effective anticancer drugs.
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Affiliation(s)
- Sefan Asamitsu
- Department of Chemistry, Graduate School of Science Kyoto University, Kitashirakawa-Oiwakecho, Sakyo, Kyoto, 606-8502, Japan.
| | - Shunsuke Obata
- Department of Chemistry, Graduate School of Science Kyoto University, Kitashirakawa-Oiwakecho, Sakyo, Kyoto, 606-8502, Japan.
| | - Zutao Yu
- Department of Chemistry, Graduate School of Science Kyoto University, Kitashirakawa-Oiwakecho, Sakyo, Kyoto, 606-8502, Japan.
| | - Toshikazu Bando
- Department of Chemistry, Graduate School of Science Kyoto University, Kitashirakawa-Oiwakecho, Sakyo, Kyoto, 606-8502, Japan.
| | - Hiroshi Sugiyama
- Department of Chemistry, Graduate School of Science Kyoto University, Kitashirakawa-Oiwakecho, Sakyo, Kyoto, 606-8502, Japan.
- Institute for Integrated Cell-Material Science (WPI-iCeMS) Kyoto University, Yoshida-Ushinomiyacho, Sakyo, Kyoto, 606-8501, Japan.
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26
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Zhou Y, Yu Y, Gao L, Fei Y, Ye T, Li Q, Zhou X, Gan N, Shao Y. Structuring polarity-inverted TBA to G-quadruplex for selective recognition of planarity of natural isoquinoline alkaloids. Analyst 2018; 143:4907-4914. [PMID: 30238092 DOI: 10.1039/c8an01561a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Efficient structuring of DNA by small molecules is very crucial in developing DNA-based novel switches with an ideal performance. In this work, we found that inverting only the polarity of the 3' terminal guanine of the thrombin-binding aptamer (3iTBA) totally eradicates the original TBA G-quadruplex (G4) structure in K+. The unstructured 3iTBA can be further refolded upon specifically interacting with small molecules of natural isoquinoline alkaloids (IAs) due to their fruitful binding patterns with variant nucleic acid structures. We identified that 3iTBA can serve as a topology selector for planar IAs. Nitidine (NIT), owing to the planar aromatic ring and coplanar substituents, is the most efficient to restructure the 3iTBA random coil toward the anti-parallel G4 conformation. However, common metal ions can't realize this structuring. The topology selector competency of 3iTBA toward IAs' planarity can be visualized using gold nanoparticles (AuNPs) as the chromogenic readout. Our work expands the G4 repertoire by exploring the polarity inversion regulation and provides a new approach to switch nucleic acid structures toward a small molecule structure-sensitive sensor.
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Affiliation(s)
- Yufeng Zhou
- Institute of Physical Chemistry, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, Zhejiang, China.
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Solís-Calero C, Augusto TM, Carvalho HF. Human-specific features of the G-quadruplex in the androgen receptor gene promoter: A comparative structural and dynamics study. J Steroid Biochem Mol Biol 2018; 182:95-105. [PMID: 29709633 DOI: 10.1016/j.jsbmb.2018.04.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 04/22/2018] [Accepted: 04/23/2018] [Indexed: 10/17/2022]
Abstract
The androgen receptor (AR) promoter contains guanine-rich regions that are able to fold into polymorphic G-quadruplex (GQ) structures, and whose deletion decreases AR gene transcription. Our attention was focused on this region because of the frequent termination of sequencing reactions during promoter methylation studies. UV and circular dichroism (CD) spectroscopy of synthetic oligonucleotides encompassing these guanine-rich regions suggested a parallel quadruplex topology with three guanine quartets and three side loops in the three cases. Melting curves revealed a lower thermostability of the human GQ compared to the rat/mouse QG structures, which is attributed to the presence of a longer central loop in the former. One molecular model is proposed for the highly similar sequences in the rat/mouse. Due to the polymorphism resulting from possible arrangements of the guanine tracts, two models were derived for the human GQ. Molecular dynamics (MD) simulations determined that both models for the human GQ had higher flexibility and lower stability than the rodent GQ models. These properties result from the presence of a longer central loop in the human GQ models, which contains 11 and 13 nucleotides, in comparison to the 2-nucleotide long loop in the rat/mouse GQ. Overall, the unveiled structural and dynamics features provide sufficient detail for the intelligent design of drugs targeting the human AR promoter.
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Affiliation(s)
- Christian Solís-Calero
- Department of Structural and Functional Biology, State University of Campinas, Campinas, São Paulo, Brazil
| | - Taize M Augusto
- Department of Structural and Functional Biology, State University of Campinas, Campinas, São Paulo, Brazil
| | - Hernandes F Carvalho
- Department of Structural and Functional Biology, State University of Campinas, Campinas, São Paulo, Brazil.
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Wiedemann B, Weisner J, Rauh D. Chemical modulation of transcription factors. MEDCHEMCOMM 2018; 9:1249-1272. [PMID: 30151079 PMCID: PMC6097187 DOI: 10.1039/c8md00273h] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 07/10/2018] [Indexed: 12/12/2022]
Abstract
Transcription factors (TFs) constitute a diverse class of sequence-specific DNA-binding proteins, which are key to the modulation of gene expression. TFs have been associated with human diseases, including cancer, Alzheimer's and other neurodegenerative diseases, which makes this class of proteins attractive targets for chemical biology and medicinal chemistry research. Since TFs lack a common binding site or structural similarity, the development of small molecules to efficiently modulate TF biology in cells and in vivo is a challenging task. This review highlights various strategies that are currently being explored for the identification and development of modulators of Myc, p53, Stat, Nrf2, CREB, ER, AR, HIF, NF-κB, and BET proteins.
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Affiliation(s)
- Bianca Wiedemann
- Technische Universität Dortmund , Fakultät für Chemie und Chemische Biologie , Otto-Hahn-Strasse 4a , D-44227 Dortmund , Germany . ; ; Tel: +49 (0)231 755 7080
| | - Jörn Weisner
- Technische Universität Dortmund , Fakultät für Chemie und Chemische Biologie , Otto-Hahn-Strasse 4a , D-44227 Dortmund , Germany . ; ; Tel: +49 (0)231 755 7080
| | - Daniel Rauh
- Technische Universität Dortmund , Fakultät für Chemie und Chemische Biologie , Otto-Hahn-Strasse 4a , D-44227 Dortmund , Germany . ; ; Tel: +49 (0)231 755 7080
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Sekibo DAT, Fox KR. The effects of DNA supercoiling on G-quadruplex formation. Nucleic Acids Res 2017; 45:12069-12079. [PMID: 29036619 PMCID: PMC5716088 DOI: 10.1093/nar/gkx856] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 09/13/2017] [Indexed: 01/06/2023] Open
Abstract
Guanine-rich DNAs can fold into four-stranded structures that contain stacks of G-quartets. Bioinformatics studies have revealed that G-rich sequences with the potential to adopt these structures are unevenly distributed throughout genomes, and are especially found in gene promoter regions. With the exception of the single-stranded telomeric DNA, all genomic G-rich sequences will always be present along with their C-rich complements, and quadruplex formation will be in competition with the corresponding Watson–Crick duplex. Quadruplex formation must therefore first require local dissociation (melting) of the duplex strands. Since negative supercoiling is known to facilitate the formation of alternative DNA structures, we have investigated G-quadruplex formation within negatively supercoiled DNA plasmids. Plasmids containing multiple copies of (G3T)n and (G3T4)n repeats, were probed with dimethylsulphate, potassium permanganate and S1 nuclease. While dimethylsulphate footprinting revealed some evidence for G-quadruplex formation in (G3T)n sequences, this was not affected by supercoiling, and permanganate failed to detect exposed thymines in the loop regions. (G3T4)n sequences were not protected from DMS and showed no reaction with permanganate. Similarly, both S1 nuclease and 2D gel electrophoresis of DNA topoisomers did not detect any supercoil-dependent structural transitions. These results suggest that negative supercoiling alone is not sufficient to drive G-quadruplex formation.
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Affiliation(s)
- Doreen A T Sekibo
- Biological Sciences, Life Sciences Building 85, University of Southampton, Southampton SO17 1BJ, UK
| | - Keith R Fox
- Biological Sciences, Life Sciences Building 85, University of Southampton, Southampton SO17 1BJ, UK
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Kankia B, Gvarjaladze D, Rabe A, Lomidze L, Metreveli N, Musier-Forsyth K. Stable Domain Assembly of a Monomolecular DNA Quadruplex: Implications for DNA-Based Nanoswitches. Biophys J 2017; 110:2169-75. [PMID: 27224482 PMCID: PMC4880955 DOI: 10.1016/j.bpj.2016.04.031] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Revised: 04/16/2016] [Accepted: 04/25/2016] [Indexed: 12/31/2022] Open
Abstract
In the presence of K+ ions, the 5′-GGGTGGGTGGGTGGG-3′ (G3T) sequence folds into a monomolecular quadruplex with unusually high thermal stability and unique optical properties. In this study we report that although single G3T molecules unfold and fold rapidly with overlapping melting and refolding curves, G3T multimers (G3T units covalently attached to each other) demonstrate highly reproducible hysteretic behavior. We demonstrate that this behavior necessitates full-length tandem G3T monomers directly conjugated to each other. Any modification of the tandem sequences eliminates the hysteresis. The experimentally measured kinetic parameters and equilibrium transition profiles suggest a highly specific two-state transition in which the folding and unfolding of the first G3T monomer is rate-limiting for both annealing and melting processes. The highly reproducible hysteretic behavior of G3T multimers has the potential to be used in the design of heat-stimulated DNA switches or transistors.
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Affiliation(s)
- Besik Kankia
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio; Institute of Biophysics, Ilia State University, Tbilisi, Republic of Georgia.
| | - David Gvarjaladze
- Institute of Biophysics, Ilia State University, Tbilisi, Republic of Georgia
| | - Adam Rabe
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio
| | - Levan Lomidze
- Institute of Biophysics, Ilia State University, Tbilisi, Republic of Georgia
| | - Nunu Metreveli
- Institute of Biophysics, Ilia State University, Tbilisi, Republic of Georgia
| | - Karin Musier-Forsyth
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio
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Li YY, Dubins DN, Le DMNT, Leung K, Macgregor RB. The role of loops and cation on the volume of unfolding of G-quadruplexes related to HTel. Biophys Chem 2017; 231:55-63. [PMID: 28162829 DOI: 10.1016/j.bpc.2016.12.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Revised: 12/21/2016] [Accepted: 12/21/2016] [Indexed: 11/28/2022]
Abstract
In aqueous solutions containing sodium or potassium cations, oligodeoxyribonucleotides (ODNs) rich in guanine form four-stranded DNA structures called G-quadruplexes (G4s). These structures are destabilized by elevated hydrostatic pressure. Here, we use pressure to investigate the volumetric changes arising from the formation of G4 structures. G4s display a great deal of structural heterogeneity that depends on the stabilizing cation as well as the oligonucleotide sequence. Using UV thermal unfolding at different pressures, we have investigated the volume change of the helix-coil equilibrium of a series of ODNs whose sequences are related to the G-rich ODN HTel (d[A(GGGTTA)3GGG]), which contains four repeats of the human telomeric sequence. The experiments are conducted in aqueous buffers containing either 100mM NaCl or KCl at pH7.4. The G4s stabilized by Na+ are less sensitive to pressure perturbation than those stabilized by K+. The overall molar volume changes (ΔVtot) of the unfolding transition for all of the G4s are large and negative. A large fraction of the measured ΔVtot value arises from the re-hydration of the cations released from the interior of the folded structure. However, the differences in the measured ΔVtot values demonstrate that variations in the structure of G4s formed by each ODN, arising from differences in the sequence of the loops, contribute significantly to ΔVtot and presumably the hydration of the folded structures. Depending on the sequence of the loops, the magnitude of the measured ΔVtot can be larger or smaller than that of HTel in solutions containing sodium. However, the magnitude of ΔVtot is smaller than HTel for the unfolding of all G4s that are stabilized by potassium ions.
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Affiliation(s)
- Yang Yun Li
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Canada
| | - David N Dubins
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Canada
| | - Dianna My Nhi Thi Le
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Canada
| | - Karen Leung
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Canada
| | - Robert B Macgregor
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Canada.
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Börner R, Kowerko D, Miserachs HG, Schaffer MF, Sigel RK. Metal ion induced heterogeneity in RNA folding studied by smFRET. Coord Chem Rev 2016. [DOI: 10.1016/j.ccr.2016.06.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Li YY, Macgregor RB. A Thermodynamic Study of Adenine and Thymine Substitutions in the Loops of the Oligodeoxyribonucleotide HTel. J Phys Chem B 2016; 120:8830-6. [PMID: 27487080 DOI: 10.1021/acs.jpcb.6b05601] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Guanine-rich DNA oligodeoxyribonucleotides (ODN) can form four-stranded structures named quadruplexes (G4s), which are stabilized via the association of four guanine bases. Quadruplexes have a high level of conformational diversity depending on the molecularity, sequence, and the cation conditions of the G4 formation. Monomolecular G4 structures have nonguanine loops that usually consist of between one and four adenine and thymine residues. In the work reported here, we systematically modified the nucleotides in the loops of the 22 nucleotide ODN, HTel, which contains four repeats of the human telomeric sequence, GGGTTA. We studied the effect of different types of bases in the loops on the stability and topology of the G4s formed. We show that lower steric hindrance of pyrimidine residues increases the stability of G4s with a major enthalpic contribution. Stacking of the loop bases onto tetrads could compensate for the loss of rotational freedom. In addition, in the presence of sodium, the stabilities of the G4s are loop dependent. In the presence of potassium, the stability of G4 depend on the sequences of each loop. Lastly, in the presence of potassium ions, the modified HTel ODNs may exist in equilibrium of the two types of the hybrid topology, and these structures are stabilized by the second loop. Modifications of the bases in this loop change the topology and stability of the folded structures.
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Affiliation(s)
- Yang Yun Li
- Department of Pharmaceutical Sciences University of Toronto , 144 College Street, Toronto, Ontario M5S 3M2, Canada
| | - Robert B Macgregor
- Department of Pharmaceutical Sciences University of Toronto , 144 College Street, Toronto, Ontario M5S 3M2, Canada
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Qiu J, Wilson A, El-Sagheer AH, Brown T. Combination probes with intercalating anchors and proximal fluorophores for DNA and RNA detection. Nucleic Acids Res 2016; 44:e138. [PMID: 27369379 PMCID: PMC5041472 DOI: 10.1093/nar/gkw579] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 06/16/2016] [Indexed: 12/20/2022] Open
Abstract
A new class of modified oligonucleotides (combination probes) has been designed and synthesised for use in genetic analysis and RNA detection. Their chemical structure combines an intercalating anchor with a reporter fluorophore on the same thymine nucleobase. The intercalator (thiazole orange or benzothiazole orange) provides an anchor, which upon hybridisation of the probe to its target becomes fluorescent and simultaneously stabilizes the duplex. The anchor is able to communicate via FRET to a proximal reporter dye (e.g. ROX, HEX, ATTO647N, FAM) whose fluorescence signal can be monitored on a range of analytical devices. Direct excitation of the reporter dye provides an alternative signalling mechanism. In both signalling modes, fluorescence in the unhybridised probe is switched off by collisional quenching between adjacent intercalator and reporter dyes. Single nucleotide polymorphisms in DNA and RNA targets are identified by differences in the duplex melting temperature, and the use of short hybridization probes, made possible by the stabilisation provided by the intercalator, enhances mismatch discrimination. Unlike other fluorogenic probe systems, placing the fluorophore and quencher on the same nucleobase facilitates the design of short probes containing multiple modifications. The ability to detect both DNA and RNA sequences suggests applications in cellular imaging and diagnostics.
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Affiliation(s)
- Jieqiong Qiu
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Adam Wilson
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Afaf H El-Sagheer
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK Chemistry Branch, Department of Science and Mathematics, Faculty of Petroleum and Mining Engineering, Suez University, Suez, 43721, Egypt
| | - Tom Brown
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK
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Largy E, Mergny JL, Gabelica V. Role of Alkali Metal Ions in G-Quadruplex Nucleic Acid Structure and Stability. Met Ions Life Sci 2016; 16:203-58. [PMID: 26860303 DOI: 10.1007/978-3-319-21756-7_7] [Citation(s) in RCA: 105] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
G-quadruplexes are guanine-rich nucleic acids that fold by forming successive quartets of guanines (the G-tetrads), stabilized by intra-quartet hydrogen bonds, inter-quartet stacking, and cation coordination. This specific although highly polymorphic type of secondary structure deviates significantly from the classical B-DNA duplex. G-quadruplexes are detectable in human cells and are strongly suspected to be involved in a number of biological processes at the DNA and RNA levels. The vast structural polymorphism exhibited by G-quadruplexes, together with their putative biological relevance, makes them attractive therapeutic targets compared to canonical duplex DNA. This chapter focuses on the essential and specific coordination of alkali metal cations by G-quadruplex nucleic acids, and most notably on studies highlighting cation-dependent dissimilarities in their stability, structure, formation, and interconversion. Section 1 surveys G-quadruplex structures and their interactions with alkali metal ions while Section 2 presents analytical methods used to study G-quadruplexes. The influence of alkali cations on the stability, structure, and kinetics of formation of G-quadruplex structures of quadruplexes will be discussed in Sections 3 and 4. Section 5 focuses on the cation-induced interconversion of G-quadruplex structures. In Sections 3 to 5, we will particularly emphasize the comparisons between cations, most often K(+) and Na(+) because of their prevalence in the literature and in cells.
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Affiliation(s)
- Eric Largy
- ARNA Laboratory, Université Bordeaux, IECB, 2, rue Robert Escarpit, F-33600, Pessac, France.,ARNA Laboratory, INSERM, U869, F-33000, Bordeaux, France
| | - Jean-Louis Mergny
- ARNA Laboratory, Université Bordeaux, IECB, 2, rue Robert Escarpit, F-33600, Pessac, France. .,ARNA Laboratory, INSERM, U869, F-33000, Bordeaux, France.
| | - Valérie Gabelica
- ARNA Laboratory, Université Bordeaux, IECB, 2, rue Robert Escarpit, F-33600, Pessac, France. .,ARNA Laboratory, INSERM, U869, F-33000, Bordeaux, France.
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Mendoza O, Elezgaray J, Mergny JL. Kinetics of quadruplex to duplex conversion. Biochimie 2015; 118:225-33. [DOI: 10.1016/j.biochi.2015.09.031] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 09/24/2015] [Indexed: 02/05/2023]
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Marušič M, Plavec J. The Effect of DNA Sequence Directionality on G-Quadruplex Folding. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201505348] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Marušič M, Plavec J. The Effect of DNA Sequence Directionality on G‐Quadruplex Folding. Angew Chem Int Ed Engl 2015; 54:11716-9. [DOI: 10.1002/anie.201505348] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 07/20/2015] [Indexed: 11/07/2022]
Affiliation(s)
- Maja Marušič
- Slovenian NMR Center, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana (Slovenia)
| | - Janez Plavec
- Slovenian NMR Center, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana (Slovenia)
- EN‐FIST Center of Excellence, 1000 Ljubljana (Slovenia)
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, 1000 Ljubljana (Slovenia)
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Tanpure AA, Srivatsan SG. Conformation-sensitive nucleoside analogues as topology-specific fluorescence turn-on probes for DNA and RNA G-quadruplexes. Nucleic Acids Res 2015. [PMID: 26202965 PMCID: PMC4678839 DOI: 10.1093/nar/gkv743] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Development of probes that can discriminate G-quadruplex (GQ) structures and indentify efficient GQ binders on the basis of topology and nucleic acid type is highly desired to advance GQ-directed therapeutic strategies. In this context, we describe the development of minimally perturbing and environment-sensitive pyrimidine nucleoside analogues, based on a 5-(benzofuran-2-yl)uracil core, as topology-specific fluorescence turn-on probes for human telomeric DNA and RNA GQs. The pyrimidine residues of one of the loop regions (TTA) of telomeric DNA and RNA GQ oligonucleotide (ON) sequences were replaced with 5-benzofuran-modified 2′-deoxyuridine and uridine analogues. Depending on the position of modification the fluorescent nucleoside analogues distinguish antiparallel, mixed parallel-antiparallel and parallel stranded DNA and RNA GQ topologies from corresponding duplexes with significant enhancement in fluorescence intensity and quantum yield. Further, these GQ sensors enabled the development of a simple fluorescence binding assay to quantify topology- and nucleic acid-specific binding of small molecule ligands to GQ structures. Together, our results demonstrate that these nucleoside analogues are useful GQ probes, which are anticipated to provide new opportunities to study and discover efficient G-quadruplex binders of therapeutic potential.
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Affiliation(s)
- Arun A Tanpure
- Department of Chemistry, Indian Institute of Science Education and Research, Pune, Dr Homi Bhabha Road, Pashan, Pune 411008, India
| | - Seergazhi G Srivatsan
- Department of Chemistry, Indian Institute of Science Education and Research, Pune, Dr Homi Bhabha Road, Pashan, Pune 411008, India
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König SLB, Evans AC, Huppert JL. Seven essential questions on G-quadruplexes. Biomol Concepts 2015; 1:197-213. [PMID: 25961997 DOI: 10.1515/bmc.2010.011] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The helical duplex architecture of DNA was discovered by Francis Crick and James Watson in 1951 and is well known and understood. However, nucleic acids can also adopt alternative structural conformations that are less familiar, although no less biologically relevant, such as the G-quadruplex. G-quadruplexes continue to be the subject of a rapidly expanding area of research, owing to their significant potential as therapeutic targets and their unique biophysical properties. This review begins by focusing on G-quadruplex structure, elucidating the intermolecular and intramolecular interactions underlying its formation and highlighting several substructural variants. A variety of methods used to characterize these structures are also outlined. The current state of G-quadruplex research is then addressed by proffering seven pertinent questions for discussion. This review concludes with an overview of possible directions for future research trajectories in this exciting and relevant field.
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Chen BJ, Wu YL, Tanaka Y, Zhang W. Small molecules targeting c-Myc oncogene: promising anti-cancer therapeutics. Int J Biol Sci 2014; 10:1084-96. [PMID: 25332683 PMCID: PMC4202025 DOI: 10.7150/ijbs.10190] [Citation(s) in RCA: 175] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 08/25/2014] [Indexed: 02/07/2023] Open
Abstract
The nuclear transcription factor c-Myc is a member of the Myc gene family with multiple functions and located on band q24.1 of chromosome 8. The c-Myc gene is activated by chromosomal translocation, rearrangement, and amplification. Its encoded protein transduces intracellular signals to the nucleus, resulting in the regulation of cell proliferation, differentiation, and apoptosis, and has the ability to transform cells and bind chromosomal DNA. c-Myc also plays a critical role in malignant transformation. The abnormal over-expression of c-Myc is frequently observed in some tumors, including carcinomas of the breast, colon, and cervix, as well as small-cell lung cancer, osteosarcomas, glioblastomas, and myeloid leukemias, therefore making it a possible target for anticancer therapy. In this minireview, we summarize unique characteristics of c-Myc and therapeutic strategies against cancer using small molecules targeting the oncogene, and discuss the prospects in the development of agents targeting c-Myc, in particular G-quadruplexes formed in c-Myc promoter and c-Myc/Max dimerization. Such information will be of importance for the research and development of c-Myc-targeted drugs.
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Affiliation(s)
- Bing-Jia Chen
- 1. Lab of Chemical Biology and Molecular Drug Design, College of Pharmaceutical Science, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou, 310014, China
| | - Yan-Ling Wu
- 2. Lab of Molecular Immunology, Virus Inspection Department, Zhejiang Provincial Center for Disease Control and Prevention, 630 Xincheng Road, Hangzhou, 310051, China. ; 1. Lab of Chemical Biology and Molecular Drug Design, College of Pharmaceutical Science, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou, 310014, China
| | - Yoshimasa Tanaka
- 3. Center for Innovation in Immunoregulative Technology and Therapeutics, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan
| | - Wen Zhang
- 1. Lab of Chemical Biology and Molecular Drug Design, College of Pharmaceutical Science, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou, 310014, China
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Ribeiro MM, Teixeira GS, Martins L, Marques MR, de Souza AP, Line SRP. G-quadruplex formation enhances splicing efficiency of PAX9 intron 1. Hum Genet 2014; 134:37-44. [PMID: 25204874 DOI: 10.1007/s00439-014-1485-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 08/25/2014] [Indexed: 11/25/2022]
Abstract
G-quadruplexes are secondary structures present in DNA and RNA molecules, which are formed by stacking of G-quartets (i.e., interaction of four guanines (G-tracts) bounded by Hoogsteen hydrogen bonding). Human PAX9 intron 1 has a putative G-quadruplex-forming region located near exon 1, which is present in all known sequenced placental mammals. Using circular dichroism (CD) analysis and CD melting, we showed that these sequences are able to form highly stable quadruplex structures. Due to the proximity of the quadruplex structure to exon-intron boundary, we used a validated double-reporter splicing assay and qPCR to analyze its role on splicing efficiency. The human quadruplex was shown to have a key role on splicing efficiency of PAX9 intron 1, as a mutation that abolished quadruplex formation decreased dramatically the splicing efficiency of human PAX9 intron 1. The less stable, rat quadruplex had a less efficient splicing when compared to human sequences. Additionally, the treatment with 360A, a strong ligand that stabilizes quadruplex structures, further increased splicing efficiency of human PAX9 intron 1. Altogether, these results provide evidences that G-quadruplex structures are involved in splicing efficiency of PAX9 intron 1.
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Affiliation(s)
- Mariana Martins Ribeiro
- Department of Morphology, Piracicaba Dental School, University of Campinas-UNICAMP, Piracicaba, SP, 13414-903, Brazil,
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Parrotta L, Ortuso F, Moraca F, Rocca R, Costa G, Alcaro S, Artese A. Targeting unimolecular G-quadruplex nucleic acids: a new paradigm for the drug discovery? Expert Opin Drug Discov 2014; 9:1167-87. [PMID: 25109710 DOI: 10.1517/17460441.2014.941353] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
INTRODUCTION G-quadruplexes (G4s) are targets of great interest because of their roles in crucial biological processes, such as aging and cancer. G4s are based on the formation of G-quartets, stabilised by Hoogsteen-type hydrogen bonds and by interaction with cations between the tetrads. These biologically relevant conformations were first discovered in eukaryotic chromosomal telomeric DNA, but have also been found in the proximal location of promoters in a number of human genes. Therefore, the extensive analysis of an intriguing target could move towards the rational drug design of new selective anticancer agents. AREAS COVERED The authors review G4 structural characterisation, with detailed insight related to the polymorphism issue. The authors describe the topologically distinct G4 structural forms and the factors involved in their interconversion mechanisms, such as the sequence of the oligonucleotides, the strand stoichiometry and orientation, the syn-anti conformation of the guanine glycosidic bonds and the G4 loop types and the environmental factors. Furthermore, the authors report several studies related to folding and unfolding kinetic profiles in order to understand the conformational view of monomolecular G4 formations. EXPERT OPINION G4 unimolecular nucleic acids can be considered as valid targets for the rational drug development of novel anticancer agents. Structural biology represents an essential link between the biology and medicinal chemistry knowledge in this field. In silico methods have already been demonstrated to be useful, especially if well integrated with biophysical tests. If this proves successful, the G4-targeting paradigm could also be extended to drug discovery beyond neoplastic pathologies.
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Affiliation(s)
- Lucia Parrotta
- Università degli Studi "Magna Græcia", Dipartimento di Scienze della Salute , Campus "S. Venuta", Viale Europa, Germaneto, 88100, Catanzaro , Italy
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44
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You H, Zeng X, Xu Y, Lim CJ, Efremov AK, Phan AT, Yan J. Dynamics and stability of polymorphic human telomeric G-quadruplex under tension. Nucleic Acids Res 2014; 42:8789-95. [PMID: 25013179 PMCID: PMC4117794 DOI: 10.1093/nar/gku581] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
As critical DNA structures capping the human chromosome ends, the stability and structural polymorphism of human telomeric G-quadruplex (G4) have drawn increasing attention in recent years. This work characterizes the equilibrium transitions of single-molecule telomeric G4 at physiological K+ concentration. We report three folded states of telomeric G4 with markedly different lifetime and mechanical stability. Our results show that the kinetically favored folding pathway is through a short-lived intermediate state to a longer-lived state. By examining the force dependence of transition rates, the force-dependent transition free energy landscape for this pathway is determined. In addition, an ultra-long-lived form of telomeric G4 structure with a much stronger mechanical stability is identified.
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Affiliation(s)
- Huijuan You
- Mechanobiology Institute, National University of Singapore, 5A Engineering Drive 1, 117411, Singapore
| | - Xiangjun Zeng
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore
| | - Yue Xu
- Mechanobiology Institute, National University of Singapore, 5A Engineering Drive 1, 117411, Singapore
| | - Ci Ji Lim
- Mechanobiology Institute, National University of Singapore, 5A Engineering Drive 1, 117411, Singapore Graduate School for Integrative Sciences and Engineering, National University of Singapore, 28 Medical Drive, 117456, Singapore Centre for Bioimaging Sciences, National University of Singapore, 14 Science Drive 4, 117546, Singapore
| | - Artem K Efremov
- Mechanobiology Institute, National University of Singapore, 5A Engineering Drive 1, 117411, Singapore
| | - Anh Tuân Phan
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore
| | - Jie Yan
- Mechanobiology Institute, National University of Singapore, 5A Engineering Drive 1, 117411, Singapore Graduate School for Integrative Sciences and Engineering, National University of Singapore, 28 Medical Drive, 117456, Singapore Centre for Bioimaging Sciences, National University of Singapore, 14 Science Drive 4, 117546, Singapore Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore
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Atomistic picture for the folding pathway of a hybrid-1 type human telomeric DNA G-quadruplex. PLoS Comput Biol 2014; 10:e1003562. [PMID: 24722458 PMCID: PMC3983051 DOI: 10.1371/journal.pcbi.1003562] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 02/26/2014] [Indexed: 12/20/2022] Open
Abstract
In this work we studied the folding process of the hybrid-1 type human telomeric DNA G-quadruplex with solvent and K(+) ions explicitly modeled. Enabled by the powerful bias-exchange metadynamics and large-scale conventional molecular dynamic simulations, the free energy landscape of this G-DNA was obtained for the first time and four folding intermediates were identified, including a triplex and a basically formed quadruplex. The simulations also provided atomistic pictures for the structures and cation binding patterns of the intermediates. The results showed that the structure formation and cation binding are cooperative and mutually supporting each other. The syn/anti reorientation dynamics of the intermediates was also investigated. It was found that the nucleotides usually take correct syn/anti configurations when they form native and stable hydrogen bonds with the others, while fluctuating between two configurations when they do not. Misfolded intermediates with wrong syn/anti configurations were observed in the early intermediates but not in the later ones. Based on the simulations, we also discussed the roles of the non-native interactions. Besides, the formation process of the parallel conformation in the first two G-repeats and the associated reversal loop were studied. Based on the above results, we proposed a folding pathway for the hybrid-1 type G-quadruplex with atomistic details, which is new and more complete compared with previous ones. The knowledge gained for this type of G-DNA may provide a general insight for the folding of the other G-quadruplexes.
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46
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Smith JE, Lu C, Taylor JS. Effect of sequence and metal ions on UVB-induced anti cyclobutane pyrimidine dimer formation in human telomeric DNA sequences. Nucleic Acids Res 2014; 42:5007-19. [PMID: 24598261 PMCID: PMC4005637 DOI: 10.1093/nar/gku163] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Irradiation of G-quadruplex forming human telomeric DNA with ultraviolet B (UVB) light results in the formation of anti cyclobutane pyrimidine dimers (CPDs) between loop 1 and loop 3 in the presence of potassium ions but not sodium ions. This was unexpected because the sequences involved favor the nonphotoreactive hybrid conformations in K+ solution, whereas a potentially photoreactive basket conformation is favored in Na+ solution. To account for these contradictory results, it was proposed that the loops are too far apart in the basket conformation in Na+ solution but close enough in a two G-tetrad basket-like form 3 conformation that can form in K+ solution. In the current study, Na+ was still found to inhibit anti CPD formation in sequences designed to stabilize the form 3 conformation. Furthermore, anti CPD formation in K+ solution was slower for the sequence previously shown to exist primarily in the proposed photoreactive form 3 conformation than the sequence shown to exist primarily in a nonphotoreactive hybrid conformation. These results suggest that the form 3 conformation is not the principal photoreactive conformation, and that G-quadruplexes in K+ solution are dynamic and able to access photoreactive conformations more easily than in Na+ solution.
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Affiliation(s)
- Jillian E Smith
- Department of Chemistry, Washington University, St. Louis, MO 63130, USA
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47
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Liu L, Shao Y, Peng J, Huang C, Liu H, Zhang L. Molecular Rotor-Based Fluorescent Probe for Selective Recognition of Hybrid G-Quadruplex and as a K+ Sensor. Anal Chem 2014; 86:1622-31. [DOI: 10.1021/ac403326m] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Lingling Liu
- Institute of Physical
Chemistry, Zhejiang Normal University, Jinhua 321004, Zhejiang, People’s Republic of China
| | - Yong Shao
- Institute of Physical
Chemistry, Zhejiang Normal University, Jinhua 321004, Zhejiang, People’s Republic of China
| | - Jian Peng
- Institute of Physical
Chemistry, Zhejiang Normal University, Jinhua 321004, Zhejiang, People’s Republic of China
| | - Chaobiao Huang
- Department
of Chemistry, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, People’s Republic of China
| | - Hua Liu
- Institute of Physical
Chemistry, Zhejiang Normal University, Jinhua 321004, Zhejiang, People’s Republic of China
| | - Lihua Zhang
- Institute of Physical
Chemistry, Zhejiang Normal University, Jinhua 321004, Zhejiang, People’s Republic of China
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48
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Zhu H, Xiao S, Liang H. Structural dynamics of human telomeric G-quadruplex loops studied by molecular dynamics simulations. PLoS One 2013; 8:e71380. [PMID: 23951152 PMCID: PMC3738534 DOI: 10.1371/journal.pone.0071380] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 06/30/2013] [Indexed: 11/18/2022] Open
Abstract
Loops which are linkers connecting G-strands and supporting the G-tetrad core in G-quadruplex are important for biological roles of G-quadruplexes. TTA loop is a common sequence which mainly resides in human telomeric DNA (hTel) G-quadruplex. A series of molecular dynamics (MD) simulations were carried out to investigate the structural dynamics of TTA loops. We found that (1) the TA base pair formed in TTA loops are very stable, the occupied of all hydrogen bonds are more than 0.95. (2) The TA base pair makes the adjacent G-quartet more stable than others. (3) For the edgewise loop and the diagonal loop, most loop bases are stacking with others, only few bases have considerable freedom. (4) The stabilities of these stacking structures are distinct. Part of the loops, especially TA base pairs, and bases stacking with the G-quartet, maintain certain stable conformations in the simulation, but other parts, like TT and TA stacking structures, are not stable enough. For the first time, spontaneous conformational switches of TTA edgewise loops were observed in our long time MD simulations. (5) For double chain reversal loop, it is really hard to maintain a stable conformation in the long time simulation under present force fields (parm99 and parmbsc0), as it has multiple conformations with similar free energies.
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Affiliation(s)
- Hong Zhu
- CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui, People's Republic of China
| | - Shiyan Xiao
- CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui, People's Republic of China
| | - Haojun Liang
- CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui, People's Republic of China
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui, People's Republic of China
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Vummidi BR, Alzeer J, Luedtke NW. Fluorescent Probes for G-Quadruplex Structures. Chembiochem 2013; 14:540-58. [DOI: 10.1002/cbic.201200612] [Citation(s) in RCA: 197] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Indexed: 12/19/2022]
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50
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Ma DL, Chan DSH, Leung CH. Drug repositioning by structure-based virtual screening. Chem Soc Rev 2013; 42:2130-41. [PMID: 23288298 DOI: 10.1039/c2cs35357a] [Citation(s) in RCA: 162] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Approved drugs have favourable or validated pharmacokinetic properties and toxicological profiles, and the repositioning of existing drugs for new indications can potentially avoid expensive costs associated with early-stage testing of the hit compounds. In recent years, technological advances in virtual screening methodologies have allowed medicinal chemists to rapidly screen drug libraries for therapeutic activity against new biomolecular targets in a cost-effective manner. This review article outlines the basic principles and recent advances in structure-based virtual screening and highlights the powerful synergy of in silico techniques in drug repositioning as demonstrated in several recent reports.
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Affiliation(s)
- Dik-Lung Ma
- Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China.
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