1
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Zeng Y, Wang Z, Zeng L, Xiong H. Enhancing or Quenching of a Mitochondria-Targeted AIEgens-Floxuridine Sensor by the Regulation of pH-Dependent Self-assembly, Efficient Recognition of Hg 2+, and Stimulated Response of GSH. Anal Chem 2023; 95:18880-18888. [PMID: 38088834 DOI: 10.1021/acs.analchem.3c04415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2023]
Abstract
Biocompatible fluorescent probes have emerged as essential tools in life sciences for visualizing subcellular structures and detecting specific analytes. Herein, we report the synthesis and characterization of a novel fluorescent probe (TPE-FdU), incorporated with hydrophilic 2'-fluoro-substituted deoxyuridine and hydrophobic ethynyl tetraphenylethene moieties, which possessed typical aggregation-induced emission (AIE) behavior. In comparison to the TPE-FdU (pKa 7.68) treated in neutral conditions, it performed well at pH 4, exhibiting an enhanced 450 nm emission signal of approximately four times stronger. As the pH value was increased to 10, the fluorescence intensity was completely quenched. The TEM images of TPE-FdU in an acidic environment (nanospherical morphology, AIE enhance, pH = 4) and in a basic environment (microrods, fluorescence quenching, pH = 9) revealed that it was a pH-dependent self-assembled probe, which was also illustrated by the interpretation of the NMR spectrum. Furthermore, the TPE-FdU probe exhibited a specific response to trace Hg2+ ions. Interestingly, the quenched fluorescence of the TPE-FdU probe caused by Hg2+ can be recovered by the addition of GSH due to the formation of the Hg-S bond being released away. MTT assay and CLSM images demonstrated that TPE-FdU was nontoxic and selectively visualized in the intracellular mitochondria. These results contributed to the development of advanced fluorescent probes with diverse applications in cell imaging, environment protection, and biomedical research.
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Affiliation(s)
- Yating Zeng
- Institute of Advanced Study, Shenzhen University, Shenzhen 518060, P. R. China
| | - Ziyan Wang
- Institute of Advanced Study, Shenzhen University, Shenzhen 518060, P. R. China
| | - Linyu Zeng
- Institute of Advanced Study, Shenzhen University, Shenzhen 518060, P. R. China
| | - Hai Xiong
- Institute of Advanced Study, Shenzhen University, Shenzhen 518060, P. R. China
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2
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Badalyan M, Vardanyan IV, Haroutiunian SG, Dalyan YB. Structural Transitions in Complementary G-Rich and C-Rich Strands and Their Mixture at Various pH Conditions. ACS OMEGA 2023; 8:47051-47056. [PMID: 38107945 PMCID: PMC10719991 DOI: 10.1021/acsomega.3c06934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 10/11/2023] [Accepted: 11/14/2023] [Indexed: 12/19/2023]
Abstract
We used circular dichroism spectroscopy, UV spectrophotometry, and differential scanning calorimetry to investigate pH-dependent structural transitions in an equimolar mixture of complementary G-rich d[5'-A(GGGTTA)3GGG-3'] (TelG) and C-rich d[3'-T(CCCAAT)3CCC-5'] (TelC) human telomeric DNA strands. Our studies were conducted at neutral (pH 7.0) and slightly acidic (pH 5.5 and 6.5) pH. We analyzed the melting thermodynamics of TelG and TelC and their equimolar mixture. Our analysis revealed that the preferred conformation of an equimolar mixture of TelG and TelC is the duplex. At pH 5.5, however, in addition to the duplex state, we observed a significant population of the i-motif state formed by TelC. Our results are consistent with the picture in which an increase in pH from 5.5 to 7.0 has little effect on the melting enthalpy of an isolated G-quadruplex while causing a strong reduction in the melting enthalpy of an isolated i-motif (the latter diminishes to 0 at pH 7.0). These effects summarily lead to a decrease in the contribution of the i-motif to the melting enthalpy of the mixture and, hence, an increase in the apparent melting enthalpy and overall stability of the duplex state.
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Affiliation(s)
- Milena
Kh. Badalyan
- Department of Molecular Physics, Yerevan State University, Yerevan 0025, Armenia
| | - Ishkhan V. Vardanyan
- Department of Molecular Physics, Yerevan State University, Yerevan 0025, Armenia
| | | | - Yeva B. Dalyan
- Department of Molecular Physics, Yerevan State University, Yerevan 0025, Armenia
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3
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El-Khoury R, Roman M, Assi HA, Moye AL, Bryan T, Damha M. Telomeric i-motifs and C-strands inhibit parallel G-quadruplex extension by telomerase. Nucleic Acids Res 2023; 51:10395-10410. [PMID: 37742080 PMCID: PMC10602923 DOI: 10.1093/nar/gkad764] [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: 05/29/2023] [Revised: 08/23/2023] [Accepted: 09/11/2023] [Indexed: 09/25/2023] Open
Abstract
Telomeric C-rich repeated DNA sequences fold into tetrahelical i-motif structures in vitro at acidic pH. While studies have suggested that i-motifs may form in cells, little is known about their potential role in human telomere biology. In this study, we explore the effect of telomeric C-strands and i-motifs on the ability of human telomerase to extend G-rich substrates. To promote i-motif formation at neutral pH, we use telomeric sequences where the cytidines have been substituted with 2'-fluoroarabinocytidine. Using FRET-based studies, we show that the stabilized i-motifs resist hybridization to concomitant parallel G-quadruplexes, implying that both structures could exist simultaneously at telomeric termini. Moreover, through telomerase activity assays, we show that both unstructured telomeric C-strands and telomeric i-motifs can inhibit the activity and processivity of telomerase extension of parallel G-quadruplexes and linear telomeric DNA. The data suggest at least three modes of inhibition by C-strands and i-motifs: direct hybridization to the substrate DNA, hybridization to nascent product DNA resulting in early telomerase dissociation, and interference with the unique mechanism of telomerase unwinding and extension of a G-quadruplex. Overall, this study highlights a potential inhibitory role for the telomeric C-strand in telomere maintenance.
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Affiliation(s)
- Roberto El-Khoury
- Department of Chemistry, McGill University, Montreal, Quebec H3A 0B8, Canada
| | - Morgane Roman
- Department of Chemistry, McGill University, Montreal, Quebec H3A 0B8, Canada
| | - Hala Abou Assi
- Department of Chemistry, McGill University, Montreal, Quebec H3A 0B8, Canada
| | - Aaron L Moye
- Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW 2145, Australia
| | - Tracy M Bryan
- Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW 2145, Australia
| | - Masad J Damha
- Department of Chemistry, McGill University, Montreal, Quebec H3A 0B8, Canada
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4
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El-Khoury R, Damha MJ. End-ligation can dramatically stabilize i-motifs at neutral pH. Chem Commun (Camb) 2023; 59:3715-3718. [PMID: 36883338 DOI: 10.1039/d2cc07063d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
Stabilizing i-motif structures at neutral pH and physiological temperature remains a major challenge. Here, we demonstrate the use of chemical end-ligation to stabilize intramolecular i-motifs at both acidic and neutral pH. We also demonstrate that combining 2'-deoxy-2'-fluoroarabinocytidine substitutions and end-ligation results in an i-motif with an unparalleled thermal stability of 54 °C at neutral pH. Overall, the ligated i-motifs presented herein may be used in screens for selective i-motif ligands and proteins and could find important applications in nanotechnology.
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Affiliation(s)
- Roberto El-Khoury
- Department of Chemistry, McGill University, Montréal, H3A0B8, Canada.
| | - Masad J Damha
- Department of Chemistry, McGill University, Montréal, H3A0B8, Canada.
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5
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i-Motif folding intermediates with zero-nucleotide loops are trapped by 2'-fluoroarabinocytidine via F···H and O···H hydrogen bonds. Commun Chem 2023; 6:31. [PMID: 36797370 PMCID: PMC9935537 DOI: 10.1038/s42004-023-00831-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 02/03/2023] [Indexed: 02/18/2023] Open
Abstract
G-quadruplex and i-motif nucleic acid structures are believed to fold through kinetic partitioning mechanisms. Such mechanisms explain the structural heterogeneity of G-quadruplex metastable intermediates which have been extensively reported. On the other hand, i-motif folding is regarded as predictable, and research on alternative i-motif folds is limited. While TC5 normally folds into a stable tetrameric i-motif in solution, we report that 2'-deoxy-2'-fluoroarabinocytidine (araF-C) substitutions can prompt TC5 to form an off-pathway and kinetically-trapped dimeric i-motif, thereby expanding the scope of i-motif folding landscapes. This i-motif is formed by two strands, associated head-to-head, and featuring zero-nucleotide loops which have not been previously observed. Through spectroscopic and computational analyses, we also establish that the dimeric i-motif is stabilized by fluorine and non-fluorine hydrogen bonds, thereby explaining the superlative stability of araF-C modified i-motifs. Comparative experimental findings suggest that the strength of these interactions depends on the flexible sugar pucker adopted by the araF-C residue. Overall, the findings reported here provide a new role for i-motifs in nanotechnology and also pose the question of whether unprecedented i-motif folds may exist in vivo.
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Pavlova I, Barinov N, Novikov R, Severov V, Iudin M, Vedekhina T, Larin A, Babenko V, Aralov A, Gnuchikh E, Sardushkin M, Klinov D, Tsvetkov V, Varizhuk A. Modeling G4s in chromatin context confirms partial nucleosome exclusion and reveals nucleosome-disrupting effects of the least selective G4 ligands. Biochimie 2023; 204:8-21. [PMID: 36063975 DOI: 10.1016/j.biochi.2022.08.016] [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: 11/05/2021] [Revised: 07/22/2022] [Accepted: 08/23/2022] [Indexed: 01/12/2023]
Abstract
G-quadruplexes (G4s) are gaining increasing attention as possible regulators of chromatin packaging, and robust approaches to their studies in pseudo-native context are much needed. Here, we designed a simple in vitro model of G4-prone genomic DNA and employed it to elucidate the impact of G4s and G4-stabilizing ligands on nucleosome occupancy. We obtained two 226-bp dsDNA constructs composed of the strong nucleosome positioning sequence and an internucleosomal DNA-imitating tail. The tail was G4-free in the control construct and harbored a "strong" (stable) G4 motif in the construct of interest. An additional "weak" (semi-stable) G4 motif was found within the canonical nucleosome positioning sequence. Both G4s were confirmed by optical methods and 1H NMR spectroscopy. Electrophoretic mobility assays showed that the weak G4 motif did not obstruct nucleosome assembly, while the strong G4 motif in the tail sequence diminished nucleosome yield. Atomic force microscopy data and molecular modeling confirmed that the strong G4 was maintained in the tail of the correctly assembled nucleosome structure. Using both in vitro and in silico models, we probed three known G4 ligands and detected nucleosome-disrupting effects of the least selective ligand. Our results are in line with the negative correlation between stable G4s and nucleosome density, support G4 tolerance between regularly positioned nucleosomes, and highlight the importance of considering chromatin context when targeting genomic G4s.
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Affiliation(s)
- Iuliia Pavlova
- Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow, 119435, Russia; Moscow Institute of Physics and Technology, Dolgoprudny, 141701, Russia
| | - Nikolay Barinov
- Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow, 119435, Russia
| | - Roman Novikov
- Engenlhardt Institute of Molecular Biology, Moscow, 119991, Russia; N.D. Zelinsky Institute of Organic Chemistry, Moscow, 19991, Russia
| | - Vjacheslav Severov
- Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow, 119435, Russia
| | - Mikhail Iudin
- Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow, 119435, Russia; Moscow Institute of Physics and Technology, Dolgoprudny, 141701, Russia
| | - Tatiana Vedekhina
- Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow, 119435, Russia
| | - Andrey Larin
- Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow, 119435, Russia; Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow, 119435, Russia
| | - Vladislav Babenko
- Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow, 119435, Russia; Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow, 119435, Russia
| | - Andrey Aralov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow, 117997, Russia
| | - Evgeny Gnuchikh
- National Research Center Kurchatov Institute, Kurchatov Genomic Center, Moscow, 123182, Russia
| | - Makar Sardushkin
- Mendeleev University of Chemical Technology of Russia, 125047, Moscow, Russia
| | - Dmitry Klinov
- Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow, 119435, Russia; Peoples' Friendship University of Russia (RUDN University), 117198, Moscow, Russia
| | - Vladimir Tsvetkov
- Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow, 119435, Russia; Institute of Biodesign and Complex System Modeling, I.M. Sechenov First Moscow State Medical University, Moscow, 119991, Russia; A.V. Topchiev Institute of Petrochemical Synthesis, Leninsky Prospect Str. 29, Moscow, 119991, Russia.
| | - Anna Varizhuk
- Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow, 119435, Russia; Moscow Institute of Physics and Technology, Dolgoprudny, 141701, Russia; Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow, 119435, Russia.
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7
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Tellurium-Modified Nucleosides, Nucleotides, and Nucleic Acids with Potential Applications. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27238379. [PMID: 36500495 PMCID: PMC9737395 DOI: 10.3390/molecules27238379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/22/2022] [Accepted: 11/23/2022] [Indexed: 12/05/2022]
Abstract
Tellurium was successfully incorporated into proteins and applied to protein structure determination through X-ray crystallography. However, studies on tellurium modification of DNA and RNA are limited. This review highlights the recent development of Te-modified nucleosides, nucleotides, and nucleic acids, and summarizes the main synthetic approaches for the preparation of 5-PhTe, 2'-MeTe, and 2'-PhTe modifications. Those modifications are compatible with solid-phase synthesis and stable during Te-oligonucleotide purification. Moreover, the ideal electronic and atomic properties of tellurium for generating clear isomorphous signals give Te-modified DNA and RNA great potential applications in 3D crystal structure determination through X-ray diffraction. STM study also shows that Te-modified DNA has strong topographic and current peaks, which immediately suggests potential applications in nucleic acid direct imaging, nanomaterials, molecular electronics, and diagnostics. Theoretical studies indicate the potential application of Te-modified nucleosides in cancer therapy.
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8
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El-Khoury R, Damha MJ. 2'-Fluoro-arabinonucleic Acid (FANA): A Versatile Tool for Probing Biomolecular Interactions. Acc Chem Res 2021; 54:2287-2297. [PMID: 33861067 DOI: 10.1021/acs.accounts.1c00125] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
This Account highlights the structural features that render 2'-deoxy-2'-fluoro-arabinonucleic acid (FANA) an ideal tool for mimicking DNA secondary structures and probing biomolecular interactions relevant to chemical biology.The high binding affinity of FANA to DNA and RNA has had implications in therapeutics. FANA can hybridize to complementary RNA, resulting in a predominant A-form helix stabilized by a network of 2'F-H8(purine) pseudohydrogen bonding interactions. We have shown that FANA/RNA hybrids are substrates of RNase H and Ago2, both implicated in the mechanism of action of antisense oligonucleotides (ASOs) and siRNA, respectvely. This knowledge has helped us study the conformational preferences of ASOs and siRNA as well as crRNA in CRISPR-associated Cas9, thereby revealing structural features crucial to biochemical activity.Additionally, FANA is of particular use in stabilizing noncanonical DNA structures. For instance, we have taken advantage of the anti N-glycosidic bond conformation of FANA monomers to induce a parallel topology in telomeric G-quadruplexes. Subsequent single-molecule FRET studies elucidated the mechanism by which these parallel G-quadruplexes are recognized and extended by telomerase. Similarly, we have utilized FANA to stabilize elusive telomeric i-motifs in the presence of concomitant parallel G-quadruplexes and under physiological conditions, thereby reinforcing their potential relevance to telomere biology. In another study, we adapted microarray technology and used FANA substitutions to enhance the binding affinity of the G-quadruplex thrombin-binding aptamer to its thrombin target.Finally, we discovered that DNA polymerases can synthesize FANA strands from DNA templates. On the basis of this property, other groups demonstrated that FANA, like DNA, can store hereditary information. They did so by engineering polymerases to efficiently transfer genetic information from DNA to FANA and retrieve it back into DNA. Subsequent studies showed that FANA could be evolved to acquire ribozyme-like endonuclease or ligase activity and to form high-affinity aptamers.Overall, the implications of these studies are remarkable because they promise a deeper understanding of human biochemistry for innovative therapeutic avenues. This Account summarizes past achievements and provides an outlook for inspiring the increased use of FANA in biological applications and fostering interdisciplinary collaborations.
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Affiliation(s)
- Roberto El-Khoury
- Department of Chemistry, McGill University, Montreal, Quebec H3A 0B8, Canada
| | - Masad J. Damha
- Department of Chemistry, McGill University, Montreal, Quebec H3A 0B8, Canada
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9
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Megalathan A, Wijesinghe KM, Ranson L, Dhakal S. Single-Molecule Analysis of Nanocircle-Embedded I-Motifs under Crowding. J Phys Chem B 2021; 125:2193-2201. [PMID: 33629846 DOI: 10.1021/acs.jpcb.0c09640] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cytosine (C)-rich regions of single-stranded DNA or RNA can fold into a tetraplex structure called i-motifs, which are typically stable under acidic pHs due to the need for protons to stabilize C-C interactions. While new studies have shown evidence for the formation of i-motifs at neutral and even physiological pH, it is not clear whether i-motifs can stably form in cells where DNA experiences topological constraint and crowding. Similarly, several studies have shown that a molecularly crowded environment promotes the formation of i-motifs at physiological pH; however, whether the intracellular crowding counteracts the topological destabilization of i-motifs is yet to be investigated. In this manuscript, using fluorescence resonance energy transfer (FRET)-based single-molecule analyses of human telomeric (hTel) i-motifs embedded in nanocircles as a proof-of-concept platform, we investigated the overall effects of crowding and topological constraint on the i-motif behavior. The smFRET analysis of the nanoassembly showed that the i-motif remains folded at pH 5.5 but unfolds at higher pHs. However, in the presence of a crowder (30% PEG 6000), i-motifs are formed at physiological pH overcoming the topological constraint imposed by the DNA nanocircles. Analysis of FRET-time traces show that the hTel sequence primarily assumes the folded state at pH ≤7.0 under crowding, but it undergoes slow conformational transitions between the folded and unfolded states at physiological pH. Our demonstration that the i-motif can form under cell-mimic crowding and topologically constrained environments may provide new insights into the potential biological roles of i-motifs and also into the design and development of i-motif-based biosensors, therapy, and other nanotechnological applications.
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Affiliation(s)
- Anoja Megalathan
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Kalani M Wijesinghe
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Leslie Ranson
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Soma Dhakal
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
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10
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Sengupta P, Bose D, Chatterjee S. The Molecular Tête-à-Tête between G-Quadruplexes and the i-motif in the Human Genome. Chembiochem 2021; 22:1517-1537. [PMID: 33355980 DOI: 10.1002/cbic.202000703] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 12/16/2020] [Indexed: 12/22/2022]
Abstract
G-Quadruplex (GQ) and i-motif structures are the paradigmatic examples of nonclassical tetrastranded nucleic acids having multifarious biological functions and widespread applications in therapeutics and material science. Recently, tetraplexes emerged as promising anticancer targets due to their structural robustness, gene-regulatory roles, and predominant distribution at specific loci of oncogenes. However, it is arguable whether the i-motif evolves in the complementary single-stranded region after GQ formation in its opposite strand and vice versa. In this review, we address the prerequisites and significance of the simultaneous and/or mutually exclusive formation of GQ and i-motif structures at complementary and sequential positions in duplexes in the cellular milieu. We discussed how their dynamic interplay Sets up cellular homeostasis and exacerbates carcinogenesis. The review gives insights into the spatiotemporal formation of GQ and i-motifs that could be harnessed to design different types of reporter systems and diagnostic platforms for potential bioanalytical and therapeutic intervention.
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Affiliation(s)
- Pallabi Sengupta
- Department of Biophysics, Bose Institute, Centenary Campus, P-1/12, C.I.T. Scheme VIIM, Kankurgachi, Kolkata, 700054, West Bengal, India
| | - Debopriya Bose
- Department of Biophysics, Bose Institute, Centenary Campus, P-1/12, C.I.T. Scheme VIIM, Kankurgachi, Kolkata, 700054, West Bengal, India
| | - Subhrangsu Chatterjee
- Department of Biophysics, Bose Institute, Centenary Campus, P-1/12, C.I.T. Scheme VIIM, Kankurgachi, Kolkata, 700054, West Bengal, India
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11
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Brown SL, Kendrick S. The i-Motif as a Molecular Target: More Than a Complementary DNA Secondary Structure. Pharmaceuticals (Basel) 2021; 14:ph14020096. [PMID: 33513764 PMCID: PMC7911047 DOI: 10.3390/ph14020096] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 01/20/2021] [Accepted: 01/22/2021] [Indexed: 12/25/2022] Open
Abstract
Stretches of cytosine-rich DNA are capable of adopting a dynamic secondary structure, the i-motif. When within promoter regions, the i-motif has the potential to act as a molecular switch for controlling gene expression. However, i-motif structures in genomic areas of repetitive nucleotide sequences may play a role in facilitating or hindering expansion of these DNA elements. Despite research on the i-motif trailing behind the complementary G-quadruplex structure, recent discoveries including the identification of a specific i-motif antibody are pushing this field forward. This perspective reviews initial and current work characterizing the i-motif and providing insight into the biological function of this DNA structure, with a focus on how the i-motif can serve as a molecular target for developing new therapeutic approaches to modulate gene expression and extension of repetitive DNA.
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12
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McKenzie LK, El-Khoury R, Thorpe JD, Damha MJ, Hollenstein M. Recent progress in non-native nucleic acid modifications. Chem Soc Rev 2021; 50:5126-5164. [DOI: 10.1039/d0cs01430c] [Citation(s) in RCA: 76] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
While Nature harnesses RNA and DNA to store, read and write genetic information, the inherent programmability, synthetic accessibility and wide functionality of these nucleic acids make them attractive tools for use in a vast array of applications.
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Affiliation(s)
- Luke K. McKenzie
- Institut Pasteur
- Department of Structural Biology and Chemistry
- Laboratory for Bioorganic Chemistry of Nucleic Acids
- CNRS UMR3523
- 75724 Paris Cedex 15
| | | | | | | | - Marcel Hollenstein
- Institut Pasteur
- Department of Structural Biology and Chemistry
- Laboratory for Bioorganic Chemistry of Nucleic Acids
- CNRS UMR3523
- 75724 Paris Cedex 15
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13
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Zhang X, Zhang Y, Zhang W. Dynamic topology of double-stranded telomeric DNA studied by single-molecule manipulation in vitro. Nucleic Acids Res 2020; 48:6458-6470. [PMID: 32496520 PMCID: PMC7337930 DOI: 10.1093/nar/gkaa479] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 05/17/2020] [Accepted: 05/27/2020] [Indexed: 12/18/2022] Open
Abstract
The dynamic topological structure of telomeric DNA is closely related to its biological function; however, no such structural information on full-length telomeric DNA has been reported due to difficulties synthesizing long double-stranded telomeric DNA. Herein, we developed an EM-PCR and TA cloning-based approach to synthesize long-chain double-stranded tandem repeats of telomeric DNA. Using mechanical manipulation assays based on single-molecule atomic force microscopy, we found that mechanical force can trigger the melting of double-stranded telomeric DNA and the formation of higher-order structures (G-quadruplexes or i-motifs). Our results show that only when both the G-strand and C-strand of double-stranded telomeric DNA form higher-order structures (G-quadruplexes or i-motifs) at the same time (e.g. in the presence of 100 mM KCl under pH 4.7), that the higher-order structure(s) can remain after the external force is removed. The presence of monovalent K+, single-wall carbon nanotubes (SWCNTs), acidic conditions, or short G-rich fragments (∼30 nt) can shift the transition from dsDNA to higher-order structures. Our results provide a new way to regulate the topology of telomeric DNA.
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Affiliation(s)
- Xiaonong Zhang
- State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, People's Republic of China
| | - Yingqi Zhang
- State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, People's Republic of China
| | - Wenke Zhang
- State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, People's Republic of China
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14
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Paudel BP, Moye AL, Abou Assi H, El-Khoury R, Cohen SB, Holien JK, Birrento ML, Samosorn S, Intharapichai K, Tomlinson CG, Teulade-Fichou MP, González C, Beck JL, Damha MJ, van Oijen AM, Bryan TM. A mechanism for the extension and unfolding of parallel telomeric G-quadruplexes by human telomerase at single-molecule resolution. eLife 2020; 9:56428. [PMID: 32723475 PMCID: PMC7426096 DOI: 10.7554/elife.56428] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 07/28/2020] [Indexed: 02/07/2023] Open
Abstract
Telomeric 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.
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Affiliation(s)
- Bishnu P Paudel
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, Australia.,Illawara Health and Medical Research Institute, Wollongong, Australia
| | - Aaron Lavel Moye
- Children's Medical Research Institute, University of Sydney, Westmead, Australia
| | - Hala Abou Assi
- Department of Chemistry, McGill University, Montreal, Canada
| | | | - Scott B Cohen
- Children's Medical Research Institute, University of Sydney, Westmead, Australia
| | - Jessica K Holien
- School of Science, College of Science, Engineering and Health, RMIT University, Melbourne, Australia
| | - Monica L Birrento
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, Australia.,Illawara Health and Medical Research Institute, Wollongong, Australia
| | - Siritron Samosorn
- Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Srinakharinwirot University, Bangkok, Thailand
| | - Kamthorn Intharapichai
- Department of Biobased Materials Science, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, Japan
| | | | - Marie-Paule Teulade-Fichou
- Institut Curie, PSL Research University, Orsay, France.,Université Paris Sud, Université Paris-Saclay, Orsay, France
| | - Carlos González
- Instituto de Química Física 'Rocasolano', CSIC, Madrid, Spain
| | - Jennifer L Beck
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, Australia.,Illawara Health and Medical Research Institute, Wollongong, Australia
| | - Masad J Damha
- Department of Chemistry, McGill University, Montreal, Canada
| | - Antoine M van Oijen
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, Australia.,Illawara Health and Medical Research Institute, Wollongong, Australia
| | - Tracy M Bryan
- Children's Medical Research Institute, University of Sydney, Westmead, Australia
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15
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Navarro A, Benabou S, Eritja R, Gargallo R. Influence of pH and a porphyrin ligand on the stability of a G-quadruplex structure within a duplex segment near the promoter region of the SMARCA4 gene. Int J Biol Macromol 2020; 159:383-393. [PMID: 32416304 DOI: 10.1016/j.ijbiomac.2020.05.062] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 04/06/2020] [Accepted: 05/09/2020] [Indexed: 12/20/2022]
Abstract
In a previous work, the formation of G-quadruplex structures in a 44-nucleotide long sequence found near the promoter region of the SMARCA4 gene was reported. The central 25 nucleotides were able to fold into an antiparallel G-quadruplex structure, the stability of which was pH-dependent. In the present work, the effect of the presence of lateral nucleotides and the complementary cytosine-rich strand on the stability of this G-quadruplex has been characterized. Moreover, the role of the model ligand TMPyP4 has been studied. Spectroscopic and separation techniques, as well as multivariate data analysis methods, have been used with these purposes. The results have shown that stability of the G-quadruplex as a function of pH or temperature is greatly reduced in the presence of the lateral nucleotides. The influence of the complementary strand does not prevent the formation of the G-quadruplex. Moreover, attempts to modulate the equilibria by an external ligand led us to determine the influence of the TMPyP4 porphyrin on these complex equilibria. This study could eventually help to understand the regulation of SMARCA4 expression.
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Affiliation(s)
- Alba Navarro
- Department of Chemical Engineering and Analytical Chemistry, University of Barcelona, Spain
| | - Sanae Benabou
- Department of Chemical Engineering and Analytical Chemistry, University of Barcelona, Spain; Université de Bordeaux, CNRS, Inserm, Laboratoire Acides Nucléiques: Régulations Naturelle et Artificielle (ARNA, U1212, UMR5320), IECB, 2 rue Robert Escarpit, 33600 Pessac, France
| | - Ramon Eritja
- Institute for Advanced Chemistry of Catalonia (IQAC), CSIC, Networking Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain
| | - Raimundo Gargallo
- Department of Chemical Engineering and Analytical Chemistry, University of Barcelona, Spain.
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16
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Megalathan A, Cox BD, Wilkerson PD, Kaur A, Sapkota K, Reiner JE, Dhakal S. Single-molecule analysis of i-motif within self-assembled DNA duplexes and nanocircles. Nucleic Acids Res 2019; 47:7199-7212. [PMID: 31287873 PMCID: PMC6698746 DOI: 10.1093/nar/gkz565] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 06/13/2019] [Accepted: 07/04/2019] [Indexed: 12/20/2022] Open
Abstract
The cytosine (C)-rich sequences that can fold into tetraplex structures known as i-motif are prevalent in genomic DNA. Recent studies of i-motif-forming sequences have shown increasing evidence of their roles in gene regulation. However, most of these studies have been performed in short single-stranded oligonucleotides, far from the intracellular environment. In cells, i-motif-forming sequences are flanked by DNA duplexes and packed in the genome. Therefore, exploring the conformational dynamics and kinetics of i-motif under such topologically constrained environments is highly relevant in predicting their biological roles. Using single-molecule fluorescence analysis of self-assembled DNA duplexes and nanocircles, we show that the topological environments play a key role on i-motif stability and dynamics. While the human telomere sequence (C3TAA)3C3 assumes i-motif structure at pH 5.5 regardless of topological constraint, it undergoes conformational dynamics among unfolded, partially folded and fully folded states at pH 6.5. The lifetimes of i-motif and the partially folded state at pH 6.5 were determined to be 6 ± 2 and 31 ± 11 s, respectively. Consistent with the partially folded state observed in fluorescence analysis, interrogation of current versus time traces obtained from nanopore analysis at pH 6.5 shows long-lived shallow blockades with a mean lifetime of 25 ± 6 s. Such lifetimes are sufficient for the i-motif and partially folded states to interact with proteins to modulate cellular processes.
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Affiliation(s)
- Anoja Megalathan
- Department of Chemistry, Virginia Commonwealth University, 1001 West Main Street, Richmond, VA 23284, USA
| | - Bobby D Cox
- Department of Physics, Virginia Commonwealth University, 701 West Grace Street, Richmond, VA 23284, USA
| | - Peter D Wilkerson
- Department of Physics, Virginia Commonwealth University, 701 West Grace Street, Richmond, VA 23284, USA
| | - Anisa Kaur
- Department of Chemistry, Virginia Commonwealth University, 1001 West Main Street, Richmond, VA 23284, USA
| | - Kumar Sapkota
- Department of Chemistry, Virginia Commonwealth University, 1001 West Main Street, Richmond, VA 23284, USA
| | - Joseph E Reiner
- Department of Physics, Virginia Commonwealth University, 701 West Grace Street, Richmond, VA 23284, USA
| | - Soma Dhakal
- Department of Chemistry, Virginia Commonwealth University, 1001 West Main Street, Richmond, VA 23284, USA
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17
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Abou Assi H, Garavís M, González C, Damha MJ. i-Motif DNA: structural features and significance to cell biology. Nucleic Acids Res 2019; 46:8038-8056. [PMID: 30124962 PMCID: PMC6144788 DOI: 10.1093/nar/gky735] [Citation(s) in RCA: 233] [Impact Index Per Article: 46.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 08/13/2018] [Indexed: 12/20/2022] Open
Abstract
The i-motif represents a paradigmatic example of the wide structural versatility of nucleic acids. In remarkable contrast to duplex DNA, i-motifs are four-stranded DNA structures held together by hemi- protonated and intercalated cytosine base pairs (C:C+). First observed 25 years ago, and considered by many as a mere structural oddity, interest in and discussion on the biological role of i-motifs have grown dramatically in recent years. In this review we focus on structural aspects of i-motif formation, the factors leading to its stabilization and recent studies describing the possible role of i-motifs in fundamental biological processes.
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Affiliation(s)
- Hala Abou Assi
- Department of Chemistry, McGill University, Montreal, QC H3A 0B8, Canada
| | - Miguel Garavís
- Instituto de Química Física 'Rocasolano', CSIC, C/Serrano 119, 28006 Madrid, Spain
| | - Carlos González
- Instituto de Química Física 'Rocasolano', CSIC, C/Serrano 119, 28006 Madrid, Spain
| | - Masad J Damha
- Department of Chemistry, McGill University, Montreal, QC H3A 0B8, Canada
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18
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Sun Y, Ji Y, Wang D, Wang J, Liu D. Stabilization of an intermolecular i-motif by lipid modification of cytosine-oligodeoxynucleotides. Org Biomol Chem 2019; 16:4857-4863. [PMID: 29926887 DOI: 10.1039/c8ob00920a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
This paper describes the stabilization of an intermolecular i-motif by lipophilic modification on the 3'-terminus of oligonucleotides. The hydrophobic aliphatic chain connected at the 3'-terminus of a trinucleotide (dC)3 promoted the formation of an i-motif and significantly enhanced the quadruplex's stability. The impact of lipophilic modification on i-motif's thermal stability was studied by UV-thermal denaturation melting experiments and isothermal titration calorimetry. We found that alkyl chains containing more than 14 carbon atoms could elevate the i-motif structure's stability in a wide range of pH and concentrations.
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Affiliation(s)
- Yawei Sun
- State Key Laboratory of Heavy Oil Processing, College of Chemical Engineering, China University of Petroleum (Huadong), Qingdao, 258000, China.
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19
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Sabale PM, Tanpure AA, Srivatsan SG. Probing the competition between duplex and G-quadruplex/i-motif structures using a conformation-sensitive fluorescent nucleoside probe. Org Biomol Chem 2019; 16:4141-4150. [PMID: 29781489 PMCID: PMC6086326 DOI: 10.1039/c8ob00646f] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Double-stranded segments of a genome that can potentially form G-quadruplex (GQ) and/or i-motif (iM) structures are considered to be important regulatory elements. Hence, the development of a common probe that can detect GQ and iM structures and also distinguish them from a duplex structure will be highly useful in understanding the propensity of such segments to adopt duplex or non-canonical four-stranded structures. Here, we describe the utility of a conformation-sensitive fluorescent nucleoside analog, which was originally developed as a GQ sensor, in detecting the iM structures of C-rich DNA oligonucleotides (ONs). The analog is based on a 5-(benzofuran-2-yl)uracil scaffold, which when incorporated into C-rich ONs (e.g., telomeric repeats) fluorescently distinguishes an iM from random coil and duplex structures. Steady-state and time-resolved fluorescence techniques enabled the determination of transition pH for the transformation of a random coil to an iM structure. Furthermore, a qualitative understanding on the relative population of duplex and GQ/iM forms under physiological conditions could be gained by correlating the fluorescence, CD and thermal melting data. Taken together, this sensor could provide a general platform to profile double-stranded promoter regions in terms of their ability to adopt four-stranded structures, and also could support approaches to discover functional GQ and iM binders.
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Affiliation(s)
- Pramod M Sabale
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune, Dr. Homi Bhabha Road, Pune 411008, India.
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20
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Debnath M, Fatma K, Dash J. Chemical Regulation of DNA i‐Motifs for Nanobiotechnology and Therapeutics. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201813288] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Manish Debnath
- School of Chemical SciencesIndian Association for the Cultivation of Science Jadavpur Kolkata- 700032 India
| | - Khushnood Fatma
- School of Chemical SciencesIndian Association for the Cultivation of Science Jadavpur Kolkata- 700032 India
| | - Jyotirmayee Dash
- School of Chemical SciencesIndian Association for the Cultivation of Science Jadavpur Kolkata- 700032 India
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21
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Debnath M, Fatma K, Dash J. Chemical Regulation of DNA i-Motifs for Nanobiotechnology and Therapeutics. Angew Chem Int Ed Engl 2019; 58:2942-2957. [PMID: 30600876 DOI: 10.1002/anie.201813288] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 12/27/2018] [Indexed: 12/20/2022]
Abstract
DNA sequences rich in cytosine have the propensity, under acidic pH, to fold into four-stranded intercalated DNA structures called i-motifs. Recent studies have provided significant breakthroughs that demonstrate how chemists can manipulate these structures for nanobiotechnology and therapeutics. The first section of this Minireview discusses the development of advanced functional nanostructures by synthetic conjugation of i-motifs with organic scaffolds and metal nanoparticles and their role in therapeutics. The second section highlights the therapeutic targeting of i-motifs with chemical scaffolds and their significance in biology. For this, first we shed light on the long-lasting debate regarding the stability of i-motifs under physiological conditions. Next, we present a comparative analysis of recently reported small molecules for specifically targeting i-motifs over other abundant DNA structures and modulating their function in cellular systems. These advances provide new insights into i-motif-targeted regulation of gene expression, telomere maintenance, and therapeutic applications.
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Affiliation(s)
- Manish Debnath
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-, 700032, India
| | - Khushnood Fatma
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-, 700032, India
| | - Jyotirmayee Dash
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-, 700032, India
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