scholarly journals PhenQE8, a Novel Ligand of the Human Telomeric Quadruplex

2021 ◽  
Vol 22 (2) ◽  
pp. 749
Author(s):  
Patricia B. Gratal ◽  
Julia G. Quero ◽  
Adrián Pérez-Redondo ◽  
Zoila Gándara ◽  
Lourdes Gude
Keyword(s):  
Equilibrium Dialysis ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
The Novel ◽  
X Ray Diffraction ◽  
Telomeric Dna ◽  
Healthy Human ◽  
Quadruplex Dna ◽  
Step Procedure ◽  
G Quadruplex

A novel quadruplex ligand based on 1,10-phenanthroline and incorporating two guanyl hydrazone functionalities, PhenQE8, is reported herein. Synthetic access was gained in a two-step procedure with an overall yield of 61%. X-ray diffraction studies revealed that PhenQE8 can adopt an extended conformation that may be optimal to favor recognition of quadruplex DNA. DNA interactions with polymorphic G-quadruplex telomeric structures were studied by different techniques, such as Fluorescence resonance energy transfer (FRET) DNA melting assays, circular dichroism and equilibrium dialysis. Our results reveal that the novel ligand PhenQE8 can efficiently recognize the hybrid quadruplex structures of the human telomeric DNA, with high binding affinity and quadruplex/duplex selectivity. Moreover, the compound shows significant cytotoxic activity against a selected panel of cultured tumor cells (PC-3, HeLa and MCF-7), whereas its cytotoxicity is considerably lower in healthy human cells (HFF-1 and RPWE-1).

scholarly journals Interactions Between Spermine-Derivatized Tentacle Porphyrins and The Human Telomeric DNA G-Quadruplex

2018 ◽  
Vol 19 (11) ◽  
pp. 3686 ◽  
Author(s):  
Navin Sabharwal ◽  
Jessica Chen ◽  
Joo Lee ◽  
Chiara Gangemi ◽  
Alessandro D'Urso ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Binding Constants ◽  
Spectroscopic Studies ◽  
Resonance Light Scattering ◽  
Binding Modes ◽  
Telomeric Dna ◽  
Binding Stoichiometry ◽  
G Quadruplex

G-rich DNA sequences have the potential to fold into non-canonical G-Quadruplex (GQ) structures implicated in aging and human diseases, notably cancers. Because stabilization of GQs at telomeres and oncogene promoters may prevent cancer, there is an interest in developing small molecules that selectively target GQs. Herein, we investigate the interactions of meso-tetrakis-(4-carboxysperminephenyl)porphyrin (TCPPSpm4) and its Zn(II) derivative (ZnTCPPSpm4) with human telomeric DNA (Tel22) via UV-Vis, circular dichroism (CD), and fluorescence spectroscopies, resonance light scattering (RLS), and fluorescence resonance energy transfer (FRET) assays. UV-Vis titrations reveal binding constants of 4.7 × 106 and 1.4 × 107 M−1 and binding stoichiometry of 2–4:1 and 10–12:1 for TCPPSpm4 and ZnTCPPSpm4, respectively. High stoichiometry is supported by the Job plot data, CD titrations, and RLS data. FRET melting indicates that TCPPSpm4 stabilizes Tel22 by 36 ± 2 °C at 7.5 eq., and that ZnTCPPSpm4 stabilizes Tel22 by 33 ± 2 °C at ~20 eq.; at least 8 eq. of ZnTCPPSpm4 are required to achieve significant stabilization of Tel22, in agreement with its high binding stoichiometry. FRET competition studies show that both porphyrins are mildly selective for human telomeric GQ vs duplex DNA. Spectroscopic studies, combined, point to end-stacking and porphyrin self-association as major binding modes. This work advances our understanding of ligand interactions with GQ DNA.

scholarly journals G-QUADRUPLEX LIGANDS AS STABILIZER TARGETING TELOMERASE ENZYME AS ANTI CANCER AGENTS

2017 ◽  
Vol 10 (8) ◽  
pp. 50
Author(s):  
Hemalatha Cn ◽  
Vijey Aanandhi M ◽  
Vijey Aanandhi M
Keyword(s):  
Basic Research ◽  
The Novel ◽  
Telomeric Dna ◽  
Inhibitor Activity ◽  
Quadruplex Dna ◽  
Biological Studies ◽  
Anti Cancer ◽  
G Quadruplex ◽  
Biophysical Studies ◽  
Lagging Strand

The human telomere stabilization with G-Quadruplex DNA tends to induce apoptosis. The molecular target of telomere cascade with a rigid molecular may show efficacious to treat cancer. The study of intercalation to human telomeric DNA with proposed ligand can be evaluated by the help of biophysical studies and biological studies. G-Quadruplex is one of the key epigenetic episodes of eukaryotes and prokaryotes, generally found in the telomeric end region, immunoglobulin switch recombination and the lagging strand of the DNA. These chemotherapeutic advances are not enough to maintain a life expectancy of cancer affected patients. A number of G-Quadruplex ligands such as acridine, perylene, and anthraquinones have been synthesized reported and evaluated them for the inhibitor activity. Therefore, translational research can pave the novel prospect to treat cancer in a fundamental way. In that connection, basic research showed G-Quadruplex phenomenon of DNA, which is having a great impact in this chemotherapy.

scholarly journals G-Quadruplexes and Their Ligands: Biophysical Methods to Unravel G-Quadruplex/Ligand Interactions

2021 ◽  
Vol 14 (8) ◽  
pp. 769
Author(s):  
Tiago Santos ◽  
Gilmar F. Salgado ◽  
Eurico J. Cabrita ◽  
Carla Cruz
Keyword(s):  
High Throughput ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Binding Mode ◽  
Titration Calorimetry ◽  
Apparent Affinity ◽  
G Quadruplex ◽  
Ligand Interactions ◽  
Types Of Information ◽  
Fluorescent Intercalator Displacement

Progress in the design of G-quadruplex (G4) binding ligands relies on the availability of approaches that assess the binding mode and nature of the interactions between G4 forming sequences and their putative ligands. The experimental approaches used to characterize G4/ligand interactions can be categorized into structure-based methods (circular dichroism (CD), nuclear magnetic resonance (NMR) spectroscopy and X-ray crystallography), affinity and apparent affinity-based methods (surface plasmon resonance (SPR), isothermal titration calorimetry (ITC) and mass spectrometry (MS)), and high-throughput methods (fluorescence resonance energy transfer (FRET)-melting, G4-fluorescent intercalator displacement assay (G4-FID), affinity chromatography and microarrays. Each method has unique advantages and drawbacks, which makes it essential to select the ideal strategies for the biological question being addressed. The structural- and affinity and apparent affinity-based methods are in several cases complex and/or time-consuming and can be combined with fast and cheap high-throughput approaches to improve the design and development of new potential G4 ligands. In recent years, the joint use of these techniques permitted the discovery of a huge number of G4 ligands investigated for diagnostic and therapeutic purposes. Overall, this review article highlights in detail the most commonly used approaches to characterize the G4/ligand interactions, as well as the applications and types of information that can be obtained from the use of each technique.

scholarly journals Extreme mechanical diversity of human telomeric DNA revealed by fluorescence-force spectroscopy

2019 ◽  
Vol 116 (17) ◽  
pp. 8350-8359 ◽  
Author(s):  
Jaba Mitra ◽  
Monika A. Makurath ◽  
Thuy T. M. Ngo ◽  
Alice Troitskaia ◽  
Yann R. Chemla ◽  
...  
Keyword(s):  
Optical Tweezers ◽  
Single Molecule ◽  
Conformational Changes ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Force Spectroscopy ◽  
Telomeric Dna ◽  
Telomeric Sequences ◽  
Substitution Mutant

G-quadruplexes (GQs) can adopt diverse structures and are functionally implicated in transcription, replication, translation, and maintenance of telomere. Their conformational diversity under physiological levels of mechanical stress, however, is poorly understood. We used single-molecule fluorescence-force spectroscopy that combines fluorescence resonance energy transfer with optical tweezers to measure human telomeric sequences under tension. Abrupt GQ unfolding with K+in solution occurred at as many as four discrete levels of force. Added to an ultrastable state and a gradually unfolding state, there were six mechanically distinct structures. Extreme mechanical diversity was also observed with Na+, although GQs were mechanically weaker. Our ability to detect small conformational changes at low forces enabled the determination of refolding forces of about 2 pN. Refolding was rapid and stochastically redistributed molecules to mechanically distinct states. A single guanine-to-thymine substitution mutant required much higher ion concentrations to display GQ-like unfolding and refolded via intermediates, contrary to the wild type. Contradicting an earlier proposal, truncation to three hexanucleotide repeats resulted in a single-stranded DNA-like mechanical behavior under all conditions, indicating that at least four repeats are required to form mechanically stable structures.

scholarly journals NovelFeIIandCoIIComplexes of Natural Product Tryptanthrin: Synthesis and Binding with G-Quadruplex DNA

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Yi-ning Zhong ◽  
Yan Zhang ◽  
Yun-qiong Gu ◽  
Shi-yun Wu ◽  
Wen-ying Shen ◽  
...  
Keyword(s):  
Natural Products ◽  
Ligand Binding ◽  
Single Crystal ◽  
Natural Product ◽  
Significant Interaction ◽  
Rational Design ◽  
X Ray Diffraction ◽  
Quadruplex Dna ◽  
X Ray ◽  
G Quadruplex

Tryptanthrin is one of the most important members of indoloquinoline alkaloids. We obtained this alkaloid fromIsatis. Two novelFeIIandCoIIcomplexes of tryptanthrin were first synthesized. Single-crystal X-ray diffraction analyses show that these complexes display distorted four-coordinated tetrahedron geometry via two heterocyclic nitrogen and oxygen atoms from tryptanthrin ligand. Binding with G-quadruplex DNA properties revealed that both complexes were found to exhibit significant interaction with G-quadruplex DNA. This study may potentially serve as the basis of future rational design of metal-based drugs from natural products that target the G-quadruplex DNA.

scholarly journals A mechanism for the extension and unfolding of parallel telomeric G-quadruplexes by human telomerase at single-molecule resolution

2020 ◽  
Author(s):  
Bishnu P. Paudel ◽  
Aaron Lavel Moye ◽  
Hala Abou Assi ◽  
Roberto El-Khoury ◽  
Scott B. Cohen ◽  
...  
Keyword(s):  
Single Molecule ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Quadruplex Structure ◽  
G Quadruplex ◽  
Nucleotide Addition ◽  
Small Molecule Ligands ◽  
Large Conformational Change ◽  
Human Telomerase ◽  
Linear Product

AbstractTelomeric G-quadruplexes (G4) were long believed to form a protective structure at telomeres, preventing their extension by the ribonucleoprotein telomerase. Contrary to this belief, we have previously demonstrated that parallel-stranded conformations of telomeric G4 can be extended by human and ciliate telomerase. However, a mechanistic understanding of the interaction of telomerase with structured DNA remained elusive. Here, we use single-molecule fluorescence resonance energy transfer (smFRET) microscopy and bulk-phase enzymology to propose a mechanism for the resolution and extension of parallel G4 by telomerase. Binding is initiated by the RNA template of telomerase interacting with the G-quadruplex; nucleotide addition then proceeds to the end of the RNA template. It is only through the large conformational change of translocation following synthesis that the G-quadruplex structure is completely unfolded to a linear product. Surprisingly, parallel G4 stabilization with either small molecule ligands or by chemical modification does not always inhibit G4 unfolding and extension by telomerase. These data reveal that telomerase is a parallel G-quadruplex resolvase.

scholarly journals Pif1 helicase unfolding of G-quadruplex DNA is highly dependent on sequence and reaction conditions

2018 ◽  
Vol 293 (46) ◽  
pp. 17792-17802 ◽  
Author(s):  
Alicia K. Byrd ◽  
Matthew R. Bell ◽  
Kevin D. Raney
Keyword(s):  
Dna Sequences ◽  
Atp Hydrolysis ◽  
Monovalent Cation ◽  
Product Formation ◽  
Telomeric Dna ◽  
Reaction Conditions ◽  
Specific Sequence ◽  
Quadruplex Dna ◽  
G Quadruplex ◽  
Pif1 Helicase

In addition to unwinding double-stranded nucleic acids, helicase activity can also unfold noncanonical structures such as G-quadruplexes. We previously characterized Pif1 helicase catalyzed unfolding of parallel G-quadruplex DNA. Here we characterized unfolding of the telomeric G-quadruplex, which can fold into antiparallel and mixed hybrid structures and found significant differences. Telomeric DNA sequences are unfolded more readily than the parallel quadruplex formed by the c-MYC promoter in K+. Furthermore, we found that under conditions in which the telomeric quadruplex is less stable, such as in Na+, Pif1 traps thermally melted quadruplexes in the absence of ATP, leading to the appearance of increased product formation under conditions in which the enzyme is preincubated with the substrate. Stable telomeric G-quadruplex structures were unfolded in a stepwise manner at a rate slower than that of duplex DNA unwinding; however, the slower dissociation from G-quadruplexes compared with duplexes allowed the helicase to traverse more nucleotides than on duplexes. Consistent with this, the rate of ATP hydrolysis on the telomeric quadruplex DNA was reduced relative to that on single-stranded DNA (ssDNA), but less quadruplex DNA was needed to saturate ATPase activity. Under single-cycle conditions, telomeric quadruplex was unfolded by Pif1, but for the c-MYC quadruplex, unfolding required multiple helicase molecules loaded onto the adjacent ssDNA. Our findings illustrate that Pif1-catalyzed unfolding of G-quadruplex DNA is highly dependent on the specific sequence and the conditions of the reaction, including both the monovalent cation and the order of addition.

scholarly journals Adenosine A2A and A3 Receptors Are Able to Interact with Each Other. A Further Piece in the Puzzle of Adenosine Receptor-Mediated Signaling

2020 ◽  
Vol 21 (14) ◽  
pp. 5070
Author(s):  
Alejandro Lillo ◽  
Eva Martínez-Pinilla ◽  
Irene Reyes-Resina ◽  
Gemma Navarro ◽  
Rafael Franco
Keyword(s):  
Adenosine Receptor ◽  
Cortical Neurons ◽  
Resonance Energy Transfer ◽  
Physiological Role ◽  
Resonance Energy ◽  
Point Of View ◽  
The Novel ◽  
Differential Signaling ◽  
A2a Receptor ◽  
Adenosine A2a

The aim of this paper was to check the possible interaction of two of the four purinergic P1 receptors, the A2A and the A3. Discovery of the A2A–A3 receptor complex was achieved by means of immunocytochemistry and of bioluminescence resonance energy transfer. The functional properties and heteromer print identification were addressed by combining binding and signaling assays. The physiological role of the novel heteromer is to provide a differential signaling depending on the pre-coupling to signal transduction components and/or on the concentration of the endogenous agonist. The main feature was that the heteromeric context led to a marked decrease of the signaling originating at A3 receptors. Interestingly from a therapeutic point of view, A2A receptor antagonists overrode the blockade, thus allowing A3 receptor-mediated signaling. The A2A–A3 receptor heteromer print was detected in primary cortical neurons. These and previous results suggest that all four adenosine receptors may interact with each other. Therefore, each adenosine receptor could form heteromers with distinct properties, expanding the signaling outputs derived from the binding of adenosine to its cognate receptors.

Bioactive papaverine derivatives bind G-quadruplexes selectively

2012 ◽  
Vol 66 (2) ◽  
Author(s):  
Elzbieta Galezowska ◽  
Joanna Kosman ◽  
Agnieszka Stepien ◽  
Blazej Rubis ◽  
Maria Rybczynska ◽  
...  
Keyword(s):  
Equilibrium Dialysis ◽  
Oxidation Products ◽  
Telomeric Sequence ◽  
Telomeric Dna ◽  
Binding Selectivity ◽  
Anti Cancer ◽  
G Quadruplex ◽  
Chloride Ligand ◽  
Papaverine Derivatives ◽  
Dna Secondary Structures

AbstractG-quadruplexes are a family of DNA secondary structures resulting from the folding of a guanine-rich sequence. Targeting quadruplexes by small molecules is an approach that is currently being studied with the aim of exploring their biological roles and developing new anti-cancer agents. There is evidence that the formation of G4 structures by telomeric DNA can be used to inhibit the enzyme activity of telomerase, and thereby to activate the pathway to senescence in tumour cells. It was previously shown that the papaverine oxidation products 6a,12a-diazadibenzo-[a,g]fluorenylium derivative (ligand I) and 2,3,9,10-tetramethoxy-12-oxo-12H-indolo[2,1-a]isoquinolinium chloride (ligand II) bind to G-quadruplex representing the human telomeric sequence. These ligands possess the ability to inhibit telomerase and polymerase action at the micromolar level. Here we report a DNA binding study on these two ligands and a new derivative 2-(2-carboxy-4,5-dimethoxyphenyl0-6,7-dimethoxyisoquiloliniuminner salt (ligand III) in order to evaluate their binding selectivity to samples of nucleic acids (ssDNA, dsDNA, triplexes, and quadruplexes). Simultaneous investigations on several DNA-ligand complexes carried out using an equilibrium dialysis approach revealed pronounced binding selectivity of ligand I and ligand II to tetraplex DNA structures over the doublestranded DNA forms.

scholarly journals Enantiomeric copper based anticancer agents promoting sequence-selective cleavage of G-quadruplex telomeric DNA and non-random cleavage of plasmid DNA

Metallomics ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 988-999 ◽  
Author(s):  
Sabiha Parveen ◽  
J. A. Cowan ◽  
Zhen Yu ◽  
Farukh Arjmand
Keyword(s):  
Anticancer Agents ◽  
Plasmid Dna ◽  
Telomeric Dna ◽  
Quadruplex Dna ◽  
Dna Cleaving ◽  
G Quadruplex

Copper-based enantiomeric anticancer agents (1S and 1R) were synthesized and studied as sequence-selective G-quadruplex DNA cleaving agents.

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