Substituted Naphthalenediimide Compounds Bind Selectively to Two Human Quadruplex Structures with Parallel Topology.
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ABSTRACT:
SUBMITTER: Vo T
PROVIDER: S-EPMC7236248 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:G-quadruplexes are noncanonical secondary structures formed in DNA sequences containing consecutive runs of guanines. DNA G-quadruplexes have recently emerged as attractive cancer therapeutic targets. It has been shown that the 3' G-rich single-stranded overhangs of human telomeres can form G-quadruplex structures. G-quadruplex-interactive compounds have been shown to inhibit telomerase access as well as telomere capping. Nuclear magnetic resonance (NMR) spectroscopy has been shown to be a powerful method in determining the G-quadruplex structures under physiologically relevant conditions. We present the NMR methodology used in our research group for structure determination of G-quadruplexes in solution and their interactions with small molecule compounds. An example of a G-quadruplex structure formed in the human telomere sequence recently solved in our laboratory is used as an example.
| S-EPMC4772873 | biostudies-literature
Project description:MOTIVATION:Quadruplexes attract the attention of researchers from many fields of bio-science. Due to a specific structure, these tertiary motifs are involved in various biological processes. They are also promising therapeutic targets in many strategies of drug development, including anticancer and neurological disease treatment. The uniqueness and diversity of their forms cause that quadruplexes show great potential in novel biological applications. The existing approaches for quadruplex analysis are based on sequence or 3D structure features and address canonical motifs only. RESULTS:In our study, we analyzed tetrads and quadruplexes contained in nucleic acid molecules deposited in Protein Data Bank. Focusing on their secondary structure topology, we adjusted its graphical diagram and proposed new dot-bracket and arc representations. We defined the novel classification of these motifs. It can handle both canonical and non-canonical cases. Based on this new taxonomy, we implemented a method that automatically recognizes the types of tetrads and quadruplexes occurring as unimolecular structures. Finally, we conducted a statistical analysis of these motifs found in experimentally determined nucleic acid structures in relation to the new classification. AVAILABILITY AND IMPLEMENTATION:https://github.com/tzok/eltetrado/. SUPPLEMENTARY INFORMATION:Supplementary data are available at Bioinformatics online.
| S-EPMC7031778 | biostudies-literature
Project description:G-quadruplexes are noncanonical secondary structures formed in DNA sequences containing consecutive runs of guanines. It has been shown that the 3' G-rich single-stranded overhangs of human telomeres can form G-quadruplex structures, and the human telomeric DNA G-quadruplexes are considered attractive targets for anticancer drugs. G-quadruplex-interactive compounds have been shown to inhibit telomerase access as well as telomere capping. Nuclear magnetic resonance (NMR) spectroscopy is a powerful method in determining the G-quadruplex structures under physiologically relevant conditions. We present the NMR and biophysical methodology used in our research group for the study of G-quadruplex structures in physiologically relevant solution and their interactions with small-molecule compounds.
| S-EPMC5516791 | biostudies-literature
Project description:G-quadruplexes are noncanonical, four-stranded nucleic acid secondary structures formed in sequences containing consecutive runs of guanines. These G-quadruplex structures have been found to form in nucleic acid regions of biological significance, including human telomeres, gene promoters, and untranslated regions of mRNA. Thus, they are considered attractive therapeutic targets. Nuclear magnetic resonance (NMR) spectroscopy is a powerful method for understanding the structures of G-quadruplexes and their interactions with small molecules under physiologically relevant conditions. Here, we present the NMR methodology used in our research group for the study of DNA G-quadruplex structures in physiologically relevant solution and their ligand interactions.
| S-EPMC7263470 | biostudies-literature
Project description:Genomic sequences susceptible to form G-quadruplexes (G4s) are always flanked by other nucleotides, but G4 formation in vitro is generally studied with short synthetic DNA or RNA oligonucleotides, for which bases adjacent to the G4 core are often omitted. Herein, we systematically studied the effects of flanking nucleotides on structural polymorphism of 371 different oligodeoxynucleotides that adopt intramolecular G4 structures. We found out that the addition of nucleotides favors the formation of a parallel fold, defined as the 'flanking effect' in this work. This 'flanking effect' was more pronounced when nucleotides were added at the 5'-end, and depended on loop arrangement. NMR experiments and molecular dynamics simulations revealed that flanking sequences at the 5'-end abolish a strong syn-specific hydrogen bond commonly found in non-parallel conformations, thus favoring a parallel topology. These analyses pave a new way for more accurate prediction of DNA G4 folding in a physiological context.
| S-EPMC8450091 | biostudies-literature
Project description:This paper concerns the Circular Dichroism (CD) and Nuclear Magnetic Resonance (NMR) structural studies of the quadruple helix arrangements adopted by three tailored oligodeoxyribonucleotide analogues, namely d(TG(Me)GGT), d(TGG(Me)GT) and d(TGGG(Me)T), where dG(Me) represents a 8-methyl-2'-deoxyguanosine residue. The results of this study clearly demonstrate that the effects of the incorporation of dG(Me) instead of a dG residue are strongly dependant upon the positioning of a single base replacement along the sequence. As such, d(TG(Me)GGT), d(TGG(Me)GT) have been found to form 4-fold symmetric quadruplexes with all strands parallel and equivalent to each other, each more stable than their natural counterpart. NMR experiments clearly indicate that [d(TG(Me)GGT)]4 possesses a G(Me)-tetrad with all dG(Me) residues in a syn-glycosidic conformation while an anti-arrangement is apparent for the four dG(Me) of [d(TGG(Me)GT)]4. As the two complexes show a quite different CD behaviour, a possible relationship between the presence of residues adopting syn-glycosidic conformations and CD profiles is briefly discussed. As far as d(TGGG(Me)T) is concerned, NMR data indicate that at 25 degrees C it exists primarily as a single-strand conformation in equilibrium with minor amounts of a quadruplex structure.
| S-EPMC1275585 | biostudies-literature
Project description:We have used a combination of simulated annealing (SA), molecular dynamics (MD) and locally enhanced sampling (LES) methods in order to predict the favourable topologies and loop conformations of dimeric DNA quadruplexes with T2 or T3 loops. This follows on from our previous MD simulation studies on the influence of loop lengths on the topology of intramolecular quadruplex structures [P. Hazel et al. (2004) J. Am. Chem. Soc., 126, 16 405-16 415], which provided results consistent with biophysical data. The recent crystal structures of d(G4T3G4)2 and d(G4BrUT2G4) (P. Hazel et al. (2006) J. Am. Chem. Soc., in press) and the NMR-determined topology of d(TG4T2G4T)2 [A.T. Phan et al. (2004) J. Mol. Biol., 338, 93-102] have been used in the present study for comparison with simulation results. These together with MM-PBSA free-energy calculations indicate that lateral T3 loops are favoured over diagonal loops, in accordance with the experimental structures; however, distinct loop conformations have been predicted to be favoured compared to those found experimentally. Several lateral and diagonal loop conformations have been found to be similar in energy. The simulations suggest an explanation for the distinct patterns of observed dimer topology for sequences with T3 and T2 loops, which depend on the loop lengths, rather than only on G-quartet stability.
| S-EPMC1449907 | biostudies-literature
Project description:G-quadruplex structures (G4s) in guanine-rich regions of DNA play critical roles in various biological phenomena, including replication, translation, and gene expression. There are three types of G4 topology, i.e., parallel, anti-parallel, and hybrid, and ligands that selectively interact with or stabilize a specific topology have been extensively explored to enable studies of topology-related functions. Here, we describe the synthesis of a new series of G4 ligands based on 6LCOs (6-linear consecutive oxazoles), i.e., L2H2-2M2EA-6LCO (2), L2A2-2M2EAc-6LCO (3), and L2G2-2M2EG-6LCO (4), which bear four aminoalkyl, acetamidealkyl, and guanidinylalkyl side chains, respectively. Among them, ligand 2 stabilized telomeric G4 and induced anti-parallel topology independently of the presence of cations. The anti-parallel topology induced by 2 was identified as chair-type by means of 19F NMR spectroscopy and fluorescence experiments with 2-aminopurine-labeled DNA.
| S-EPMC9058415 | biostudies-literature
Project description:We studied photochemical reactions of BrU-substituted G-quadruplex (G4) DNA substrates with two pyrene-substituted polyazamacrocyclic ligands, M-1PY and M-2PY. Both ligands bind to and stabilize G4-DNA structures without altering their folding topology, as demonstrated by FRET-melting experiments, fluorimetric titrations and CD spectroscopy. Notably, the bis-pyrene derivative (M-2PY) behaves as a significantly more affine and selective G4 ligand, compared with its mono-pyrene counterpart (M-1PY) and control compounds. Upon short UVA irradiation (365?nm) both ligands, in particular M-2PY, efficiently sensitize photoreactions at BrU residues incorporated in G4 structures and give rise to two kinds of photoproducts, namely DNA strand cleavage and covalent ligand-DNA photoadducts. Remarkably, the photoinduced strand cleavage is observed exclusively with G4 structures presenting BrU residues in lateral or diagonal loops, but not with parallel G4-DNA structures presenting only propeller loops. In contrast, the formation of fluorescent photoadducts is observed with all BrU-substituted G4-DNA substrates, with M-2PY giving significantly higher yields (up to 27%) than M-1PY. Both ligand-sensitized photoreactions are specific to BrU-modified G4-DNA structures with respect to double-stranded or stem-loop substrates. Thus, ligand-sensitized photoreactions with BrU-substituted G4-DNA may be exploited (i) as a photochemical probe, allowing "photofootprinting" of G4 folding topologies in vitro and (ii) for covalent trapping of G4 structures as photoadducts with pyrene-substituted ligands.
| S-EPMC6202380 | biostudies-literature
Project description:In the first of the compounds reported herein, namely 6'-ferrocenyl-6a'-nitro-6',6a',6b',7',9',11a'-hexa-hydro-2H-spiro-[ace-naphthyl-ene-1,11'-chromeno[3',4':3,4]pyrrolo-[1,2-c]thia-zol]-2-one, [Fe(C5H5)(C29H21N2O4S)], (I), the thia-zolidine ring adopts a twist conformation on the methine N-C atoms. In the second compound, viz. 6'-(4-methoxy-phen-yl)-6a'-nitro-6',6a',6b',7',9',11a'-hexa-hydro-2H-spiro-[ace-naphthyl-ene-1,11'-chromeno[3',4':3,4]pyrrolo-[1,2-c]thia-zol]-2-one, [Fe(C5H5)(C26H19N2O5S)], (II), the thia-zolidine ring adopts an envelope conformation with a methine C atom as the flap. In both compounds, the pyrrolidine ring adopts a twist conformation on the thia-zolidine and tetra-hydro-pyran C atoms. The mean planes of the thia-zolidine and pyrrolidine rings subtend angles of 67.30?(1) and 62.95?(7)° in (I) and (II), respectively, while the mean plane of the pyrrolidine ring makes dihedral angles of 76.53?(1) and 87.74?(7)° with the ace-naphthyl-ene ring system in (I) and (II), respectively. In both compounds, an intra-molecular C-H?O hydrogen bond forms an S(7) ring motif. In the crystal of (I), mol-ecules are linked via two different C-H?O hydrogen bonds, forming chains along [001] and [100]. In (II), they are linked through C-H?O hydrogen bonds, forming dimers with an R 2 (2)(10) ring motif while C-H?? inter-actions link the mol-ecules in a head-to-tail fashion, forming chains along the a-axis direction.
| S-EPMC4971855 | biostudies-other