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Tao S, Run Y, Monchaud D, Zhang W. i-Motif DNA: identification, formation, and cellular functions. Trends Genet 2024:S0168-9525(24)00133-1. [PMID: 38902139 DOI: 10.1016/j.tig.2024.05.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Revised: 05/29/2024] [Accepted: 05/29/2024] [Indexed: 06/22/2024]
Abstract
An i-motif (iM) is a four-stranded (quadruplex) DNA structure that folds from cytosine (C)-rich sequences. iMs can fold under many different conditions in vitro, which paves the way for their formation in living cells. iMs are thought to play key roles in various DNA transactions, notably in the regulation of genome stability, gene transcription, mRNA translation, DNA replication, telomere and centromere functions, and human diseases. We summarize the different techniques used to assess the folding of iMs in vitro and provide an overview of the internal and external factors that affect their formation and stability in vivo. We describe the possible biological relevance of iMs and propose directions towards their use as target in biology.
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Affiliation(s)
- Shentong Tao
- State Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, Collaborative Innovation Center for Modern Crop Production (CIC-MCP), Nanjing Agricultural University, 1 Weigang, Nanjing, Jiangsu 210095, China
| | - Yonghang Run
- State Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, Collaborative Innovation Center for Modern Crop Production (CIC-MCP), Nanjing Agricultural University, 1 Weigang, Nanjing, Jiangsu 210095, China
| | - David Monchaud
- Institut de Chimie Moleculaire de l'Université de Bourgogne (ICMUB), Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche (UMR) 6302, Université Bourgogne Franche Comté (UBFC), Dijon, France
| | - Wenli Zhang
- State Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, Collaborative Innovation Center for Modern Crop Production (CIC-MCP), Nanjing Agricultural University, 1 Weigang, Nanjing, Jiangsu 210095, China.
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2
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Alanazi AFR, Parkinson GN, Haider S. Structural Motifs at the Telomeres and Their Role in Regulatory Pathways. Biochemistry 2024; 63:827-842. [PMID: 38481135 PMCID: PMC10993422 DOI: 10.1021/acs.biochem.4c00023] [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: 04/04/2024]
Abstract
Telomeres are specialized structures, found at the ends of linear chromosomes in eukaryotic cells, that play a crucial role in maintaining the stability and integrity of genomes. They are composed of repetitive DNA sequences, ssDNA overhangs, and several associated proteins. The length of telomeres is linked to cellular aging in humans, and deficiencies in their maintenance are associated with various diseases. Key structural motifs at the telomeres serve to protect vulnerable chromosomal ends. Telomeric DNA also has the ability to form diverse complex DNA higher-order structures, including T-loops, D-loops, R-loops, G-loops, G-quadruplexes, and i-motifs, in the complementary C-rich strand. While many essential proteins at telomeres have been identified, the intricacies of their interactions and structural details are still not fully understood. This Perspective highlights recent advancements in comprehending the structures associated with human telomeres. It emphasizes the significance of telomeres, explores various telomeric structural motifs, and delves into the structural biology surrounding telomeres and telomerase. Furthermore, telomeric loops, their topologies, and the associated proteins that contribute to the safeguarding of telomeres are discussed.
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Affiliation(s)
- Abeer F R Alanazi
- UCL School of Pharmacy, University College London, London WC1N 1AX, United Kingdom
| | - Gary N Parkinson
- UCL School of Pharmacy, University College London, London WC1N 1AX, United Kingdom
| | - Shozeb Haider
- UCL School of Pharmacy, University College London, London WC1N 1AX, United Kingdom
- UCL Centre for Advanced Research Computing, University College London, London WC1H 9RN, United Kingdom
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3
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Víšková P, Ištvánková E, Ryneš J, Džatko Š, Loja T, Živković ML, Rigo R, El-Khoury R, Serrano-Chacón I, Damha MJ, González C, Mergny JL, Foldynová-Trantírková S, Trantírek L. In-cell NMR suggests that DNA i-motif levels are strongly depleted in living human cells. Nat Commun 2024; 15:1992. [PMID: 38443388 PMCID: PMC10914786 DOI: 10.1038/s41467-024-46221-y] [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: 09/10/2023] [Accepted: 02/13/2024] [Indexed: 03/07/2024] Open
Abstract
I-Motifs (iM) are non-canonical DNA structures potentially forming in the accessible, single-stranded, cytosine-rich genomic regions with regulatory roles. Chromatin, protein interactions, and intracellular properties seem to govern iM formation at sites with i-motif formation propensity (iMFPS) in human cells, yet their specific contributions remain unclear. Using in-cell NMR with oligonucleotide iMFPS models, we monitor iM-associated structural equilibria in asynchronous and cell cycle-synchronized HeLa cells at 37 °C. Our findings show that iMFPS displaying pHT < 7 under reference in vitro conditions occur predominantly in unfolded states in cells, while those with pHT > 7 appear as a mix of folded and unfolded states depending on the cell cycle phase. Comparing these results with previous data obtained using an iM-specific antibody (iMab) reveals that cell cycle-dependent iM formation has a dual origin, and iM formation concerns only a tiny fraction (possibly 1%) of genomic sites with iM formation propensity. We propose a comprehensive model aligning observations from iMab and in-cell NMR and enabling the identification of iMFPS capable of adopting iM structures under physiological conditions in living human cells. Our results suggest that many iMFPS may have biological roles linked to their unfolded states.
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Affiliation(s)
- Pavlína Víšková
- Central European Institute of Technology, Masaryk University, 625 00, Brno, Czech Republic
- National Centre for Biomolecular Research, Masaryk University, 625 00, Brno, Czech Republic
| | - Eva Ištvánková
- Central European Institute of Technology, Masaryk University, 625 00, Brno, Czech Republic
- National Centre for Biomolecular Research, Masaryk University, 625 00, Brno, Czech Republic
| | - Jan Ryneš
- Central European Institute of Technology, Masaryk University, 625 00, Brno, Czech Republic
| | - Šimon Džatko
- Central European Institute of Technology, Masaryk University, 625 00, Brno, Czech Republic
- Centre for Advanced Materials Application, Slovak Academy of Sciences, 845 11, Bratislava, Slovakia
| | - Tomáš Loja
- Central European Institute of Technology, Masaryk University, 625 00, Brno, Czech Republic
| | - Martina Lenarčič Živković
- Central European Institute of Technology, Masaryk University, 625 00, Brno, Czech Republic
- Slovenian NMR Centre, National Institute of Chemistry, SI-1000, Ljubljana, Slovenia
| | - Riccardo Rigo
- Central European Institute of Technology, Masaryk University, 625 00, Brno, Czech Republic
- Pharmaceutical and Pharmacological Sciences Department, University of Padova, 35131, Padova, Italy
| | - Roberto El-Khoury
- Department of Chemistry, McGill University, Montreal, QC, H3A0B8, Canada
| | - Israel Serrano-Chacón
- Instituto de Química Física 'Blas Cabrera', CSIC, C/Serrano 119, 28006, Madrid, Spain
| | - Masad J Damha
- Department of Chemistry, McGill University, Montreal, QC, H3A0B8, Canada
| | - Carlos González
- Instituto de Química Física 'Blas Cabrera', CSIC, C/Serrano 119, 28006, Madrid, Spain
| | - Jean-Louis Mergny
- Institute of Biophysics, Czech Academy of Sciences, Brno, 612 00, Czech Republic
- Laboratoire d'Optique & Biosciences, Institut Polytechnique de Paris, Inserm, CNRS, Ecole Polytechnique, Palaiseau, 91120, France
| | - Silvie Foldynová-Trantírková
- Central European Institute of Technology, Masaryk University, 625 00, Brno, Czech Republic.
- Institute of Biophysics, Czech Academy of Sciences, Brno, 612 00, Czech Republic.
| | - Lukáš Trantírek
- Central European Institute of Technology, Masaryk University, 625 00, Brno, Czech Republic.
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4
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Feng Y, Ma X, Yang Y, Tao S, Ahmed A, Gong Z, Cheng X, Zhang W. The roles of DNA methylation on pH dependent i-motif (iM) formation in rice. Nucleic Acids Res 2024; 52:1243-1257. [PMID: 38180820 PMCID: PMC10853798 DOI: 10.1093/nar/gkad1245] [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: 06/27/2023] [Revised: 12/14/2023] [Accepted: 12/19/2023] [Indexed: 01/07/2024] Open
Abstract
I-motifs (iMs) are four-stranded non-B DNA structures containing C-rich DNA sequences. The formation of iMs is sensitive to pH conditions and DNA methylation, although the extent of which is still unknown in both humans and plants. To investigate this, we here conducted iMab antibody-based immunoprecipitation and sequencing (iM-IP-seq) along with bisulfite sequencing using CK (original genomic DNA without methylation-related treatments) and hypermethylated or demethylated DNA at both pH 5.5 and 7.0 in rice, establishing a link between pH, DNA methylation and iM formation on a genome-wide scale. We found that iMs folded at pH 7.0 displayed higher methylation levels than those formed at pH 5.5. DNA demethylation and hypermethylation differently influenced iM formation at pH 7.0 and 5.5. Importantly, CG hypo-DMRs (differentially methylated regions) and CHH (H = A, C and T) hyper-DMRs alone or coordinated with CG/CHG hyper-DMRs may play determinant roles in the regulation of pH dependent iM formation. Thus, our study shows that the nature of DNA sequences alone or combined with their methylation status plays critical roles in determining pH-dependent formation of iMs. It therefore deepens the understanding of the pH and methylation dependent modulation of iM formation, which has important biological implications and practical applications.
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Affiliation(s)
- Yilong Feng
- State Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, CIC-MCP, Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, China
| | - Xing Ma
- State Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, CIC-MCP, Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, China
| | - Ying Yang
- State Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, CIC-MCP, Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, China
| | - Shentong Tao
- State Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, CIC-MCP, Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, China
| | - Asgar Ahmed
- State Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, CIC-MCP, Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, China
- Bangladesh Wheat and Maize Research Institute (BWMRI), Nashipur, Dinajpur 5200, Bangladesh
| | - Zhiyun Gong
- Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding, Agricultural College of Yangzhou University, Yangzhou 225009, China
| | - Xuejiao Cheng
- State Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, CIC-MCP, Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, China
| | - Wenli Zhang
- State Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, CIC-MCP, Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, China
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5
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Ghezzo M, Grigoletto L, Rigo R, Herdewijn P, Groaz E, Sissi C. Modulation of the tetrameric I-motif folding of C-rich Tetrahymena telomeric sequences by hexitol nucleic acid (HNA) modifications. Biochimie 2023; 214:112-122. [PMID: 37558081 DOI: 10.1016/j.biochi.2023.08.003] [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: 04/24/2023] [Revised: 08/01/2023] [Accepted: 08/06/2023] [Indexed: 08/11/2023]
Abstract
I-motifs are non-canonical DNA structures consisting of two parallel strands held together by hemiprotonated cytosine-cytosine+ base pairs, which intercalate to form a ordered column of stacked base pairs. This unique structure covers potential relevance in various fields, including gene regulation and biotechnological applications. A unique structural feature of I-motifs (iM), is the presence of sugar-sugar interactions through their extremely narrow minor grooves. Consistently, oligonucleotides containing pentose derivatives such as ribose, 2'-deoxyribose, arabinose, and 2'-deoxy-2'-fluoroarabinose highlighted a very different attitude to fold into iM. On the other hand, there is significant attention focused on exploring sugar-modifications that can increase nucleic acids resistance to nuclease degradation, a crucial requirement for therapeutic applications. An interesting example, not addressed in the iM field yet, is represented by hexitol nucleic acid (HNA), a metabolically stable six-membered ring analogue compatible with A-like double helix formation. Herein, we selected two DNA C-rich Tetrahymena telomeric sequences whose tetrameric iMs were already resolved by NMR and we investigated the iM folding of related HNA and RNA oligonucleotides by circular dichroism, differential scanning calorimetry and NMR. The comparison of their behaviours vs the DNA counterparts provided interesting insights into the influence of the sugar on iM folding. In particular, ribose and hexitol prevented iM formation. However, by clustering the hexitol-containing residues at the 3'-end, it was possible to modulate the distribution of the different topological species described for the DNA iMs. These data open new avenues for the exploitation of sugar modifications for I-motif characterization and applications.
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Affiliation(s)
- Michele Ghezzo
- Dept. of Pharmaceutical and Pharmacological Sciences, University of Padova, v. Marzolo 5 35131, Padova, Italy
| | - Luca Grigoletto
- Dept. of Pharmaceutical and Pharmacological Sciences, University of Padova, v. Marzolo 5 35131, Padova, Italy; KU Leuven, Rega Institute for Medical Research, Medicinal Chemistry, Herestraat 49-Box 1041, 3000, Leuven, Belgium
| | - Riccardo Rigo
- Dept. of Pharmaceutical and Pharmacological Sciences, University of Padova, v. Marzolo 5 35131, Padova, Italy
| | - Piet Herdewijn
- KU Leuven, Rega Institute for Medical Research, Medicinal Chemistry, Herestraat 49-Box 1041, 3000, Leuven, Belgium
| | - Elisabetta Groaz
- Dept. of Pharmaceutical and Pharmacological Sciences, University of Padova, v. Marzolo 5 35131, Padova, Italy; KU Leuven, Rega Institute for Medical Research, Medicinal Chemistry, Herestraat 49-Box 1041, 3000, Leuven, Belgium.
| | - Claudia Sissi
- Dept. of Pharmaceutical and Pharmacological Sciences, University of Padova, v. Marzolo 5 35131, Padova, Italy.
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6
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Rodgers MT, Seidu YS, Israel E. Influence of 2'-Modifications (O-Methylation, Fluorination, and Stereochemical Inversion) on the Base Pairing Energies of Protonated Cytidine Nucleoside Analogue Base Pairs: Implications for the Stabilities of i-Motif Structures. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2023. [PMID: 37294839 DOI: 10.1021/jasms.3c00108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Naturally occurring and chemically engineered modifications are among the most powerful strategies explored for fine-tuning the conformational characteristics and intrinsic stability of nucleic acids topologies. Modifications at the 2'-position of the ribose or 2'-deoxyribose moieties differentiate nucleic acid structures and have a significant impact on their electronic properties and base-pairing interactions. 2'-O-Methylation, a common post-transcriptional modification of tRNA, is directly involved in modulating specific anticodon-codon base-pairing interactions. 2'-Fluorinated and arabino nucleosides possess novel and beneficial medicinal properties and find use as therapeutics for treating viral diseases and cancer. However, the potential to deploy 2'-modified cytidine chemistries for tuning i-motif stability is largely unknown. To address this knowledge gap, the effects of 2'-modifications including O-methylation, fluorination, and stereochemical inversion on the base-pairing interactions of protonated cytidine nucleoside analogue base pairs, the core stabilizing interactions of i-motif structures, are examined using complementary threshold collision-induced dissociation techniques and computational methods. The 2'-modified cytidine nucleoside analogues investigated here include 2'-O-methylcytidine, 2'-fluoro-2'-deoxycytidine, arabinofuranosylcytosine, 2'-fluoro-arabinofuranosylcytosine, and 2',2'-difluoro-2'-deoxycytidine. All five 2'-modifications examined here are found to enhance the base-pairing interactions relative to the canonical DNA and RNA cytidine nucleosides with the greatest enhancements arising from 2'-O-methylation and 2',2'-difluorination, suggesting that these modifications should well be tolerated in the narrow grooves of i-motif conformations.
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Affiliation(s)
- M T Rodgers
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | - Yakubu S Seidu
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | - E Israel
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
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7
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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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Luo X, Zhang J, Gao Y, Pan W, Yang Y, Li X, Chen L, Wang C, Wang Y. Emerging roles of i-motif in gene expression and disease treatment. Front Pharmacol 2023; 14:1136251. [PMID: 37021044 PMCID: PMC10067743 DOI: 10.3389/fphar.2023.1136251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 02/27/2023] [Indexed: 03/22/2023] Open
Abstract
As non-canonical nucleic acid secondary structures consisting of cytosine-rich nucleic acids, i-motifs can form under certain conditions. Several i-motif sequences have been identified in the human genome and play important roles in biological regulatory functions. Due to their physicochemical properties, these i-motif structures have attracted attention and are new targets for drug development. Herein, we reviewed the characteristics and mechanisms of i-motifs located in gene promoters (including c-myc, Bcl-2, VEGF, and telomeres), summarized various small molecule ligands that interact with them, and the possible binding modes between ligands and i-motifs, and described their effects on gene expression. Furthermore, we discussed diseases closely associated with i-motifs. Among these, cancer is closely associated with i-motifs since i-motifs can form in some regions of most oncogenes. Finally, we introduced recent advances in the applications of i-motifs in multiple areas.
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Affiliation(s)
| | | | | | | | | | | | | | - Chang Wang
- *Correspondence: Chang Wang, ; Yuqing Wang,
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9
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López-Tena M, Chen SK, Winssinger N. Supernatural: Artificial Nucleobases and Backbones to Program Hybridization-Based Assemblies and Circuits. Bioconjug Chem 2023; 34:111-123. [PMID: 35856656 DOI: 10.1021/acs.bioconjchem.2c00292] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The specificity and predictability of hybridization make oligonucleotides a powerful platform to program assemblies and networks with logic-gated responses, an area of research which has grown into a field of its own. While the field has capitalized on the commercial availability of DNA oligomers with its four canonical nucleobases, there are opportunities to extend the capabilities of the hardware with unnatural nucleobases and other backbones. This Topical Review highlights nucleobases that favor hybridizations that are empowering for assemblies and networks as well as two chiral XNAs than enable orthogonal hybridization networks.
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Affiliation(s)
- Miguel López-Tena
- University of Geneva, Department of Organic Chemistry, Faculty of Science, NCCR Chemical Biology, 30 Quai Ernest Ansermet, CH-1205 Geneva, Switzerland
| | - Si-Kai Chen
- University of Geneva, Department of Organic Chemistry, Faculty of Science, NCCR Chemical Biology, 30 Quai Ernest Ansermet, CH-1205 Geneva, Switzerland
| | - Nicolas Winssinger
- University of Geneva, Department of Organic Chemistry, Faculty of Science, NCCR Chemical Biology, 30 Quai Ernest Ansermet, CH-1205 Geneva, Switzerland
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10
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Rodgers MT, Seidu YS, Israel E. Influence of 5-Halogenation on the Base-Pairing Energies of Protonated Cytidine Nucleoside Analogue Base Pairs: Implications for the Stabilities of Synthetic i-Motif Structures for DNA Nanotechnology Applications. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:1697-1715. [PMID: 35921530 DOI: 10.1021/jasms.2c00137] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
DNA nanotechnology has been employed to develop devices based on i-motif structures. The protonated cytosine-cytosine base pairs that stabilize i-motif conformations are favored under slightly acidic conditions. This unique property has enabled development of the first DNA molecular motor driven by pH changes. The ability to alter the stability and pH transition range of such DNA molecular motors is desirable. Understanding how i-motif structures are influenced by modifications, and which modifications enhance stability and/or affect the pH characteristics, are therefore of great interest. Here, the influence of 5-halogenation of the cytosine nucleobases on the base pairing of protonated cytidine nucleoside analogue base pairs is examined using complementary threshold collision-induced dissociation techniques and computational methods. The nucleoside analogues examined here include the 5-halogenated forms of the canonical DNA and RNA cytidine nucleosides. Comparisons among these systems and to the analogous canonical base pairs previously examined enable the influence of 5-halogenation and the 2'-hydroxy substituent on the base pairing to be elucidated. 5-Halogenation of the cytosine nucleobases is found to enhance the strength of base pairing of DNA base pairs and generally weakens the base pairing for RNA base pairs. Trends in the strength of base pairing indicate that both inductive and polarizability effects influence the strength of base pairing. Overall, the present results suggest that 5-halogenation, and in particular, 5-fluorination and 5-iodination, provide effective means of stabilizing DNA i-motif conformations for applications in nanotechnology, whereas only 5-iodination is effective for stabilizing RNA i-motif conformations but the enhancement in stability is less significant.
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Affiliation(s)
- M T Rodgers
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | - Yakubu S Seidu
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | - E Israel
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
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11
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Stability and context of intercalated motifs (i-motifs) for biological applications. Biochimie 2022; 198:33-47. [PMID: 35259471 DOI: 10.1016/j.biochi.2022.03.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 02/21/2022] [Accepted: 03/03/2022] [Indexed: 11/24/2022]
Abstract
DNA is naturally dynamic and can self-assemble into alternative secondary structures including the intercalated motif (i-motif), a four-stranded structure formed in cytosine-rich DNA sequences. Until recently, i-motifs were thought to be unstable in physiological cellular environments. Studies demonstrating their existence in the human genome and role in gene regulation are now shining light on their biological relevance. Herein, we review the effects of epigenetic modifications on i-motif structure and stability, and biological factors that affect i-motif formation within cells. Furthermore, we highlight recent progress in targeting i-motifs with structure-specific ligands for biotechnology and therapeutic purposes.
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12
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Kimura K, Oshikawa D, Ikebukuro K, Yoshida W. Stabilization of VEGF i-motif structure by CpG methylation. Biochem Biophys Res Commun 2022; 594:88-92. [PMID: 35078112 DOI: 10.1016/j.bbrc.2022.01.054] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 01/13/2022] [Accepted: 01/13/2022] [Indexed: 11/02/2022]
Abstract
The intercalated motif (i-motif) is a non-canonical nucleic acid structure formed by intercalated hemi-protonated cytosine base pairs (C-C+) under acidic conditions. The i-motif structure formation is involved in biological processes such as transcription regulation. Therefore, the identification of factors controlling i-motif formation is important in elucidating the cellular functions it controls. We previously reported that the VEGF G-quadruplex structure is stabilized by CpG methylation. In this study, the effect of CpG methylation on the stability of the VEGF i-motif structure was investigated. The VEGF i-motif-forming oligonucleotide contains four cytosines on CpG sites, and three of the four cytosines (C4, C15, and C20) are involved in C-C+ formation in the i-motif structure. Circular dichroism (CD) spectra analysis demonstrated that full CpG methylation increased the pH of mid transition (pHT) of the i-motif structure by 0.1, and the melting temperature (Tm) by 5.1 °C in 25 mM sodium cacodylate buffer at pH 5.0. Moreover, single methylation at C4, C15, and C20 increased Tm by 0.5, 1.7, and 2.0 °C in the buffer, respectively. These results demonstrated that CpG methylation stabilized the VEGF i-motif structure.
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Affiliation(s)
- Kosuke Kimura
- Graduate School of Bionics, Tokyo University of Technology, 1404-1 Katakura, Hachioji, Tokyo, 192-0982, Japan
| | - Daiki Oshikawa
- Graduate School of Management of Technology, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo, 184-8588, Japan
| | - Kazunori Ikebukuro
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo, 184-8588, Japan.
| | - Wataru Yoshida
- Graduate School of Bionics, Tokyo University of Technology, 1404-1 Katakura, Hachioji, Tokyo, 192-0982, Japan; School of Bioscience and Biotechnology, Tokyo University of Technology, 1404-1 Katakura, Hachioji, Tokyo, 192-0982, Japan.
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13
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The Dynamic Regulation of G-Quadruplex DNA Structures by Cytosine Methylation. Int J Mol Sci 2022; 23:ijms23052407. [PMID: 35269551 PMCID: PMC8910436 DOI: 10.3390/ijms23052407] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 02/16/2022] [Accepted: 02/17/2022] [Indexed: 02/01/2023] Open
Abstract
It is well known that certain non B-DNA structures, including G-quadruplexes, are key elements that can regulate gene expression. Here, we explore the theory that DNA modifications, such as methylation of cytosine, could act as a dynamic switch by promoting or alleviating the structural formation of G-quadruplex structures in DNA or RNA. The interaction between epigenetic DNA modifications, G4 formation, and the 3D architecture of the genome is a complex and developing area of research. Although there is growing evidence for such interactions, a great deal still remains to be discovered. In vivo, the potential effect that cytosine methylation may have on the formation of DNA structures has remained largely unresearched, despite this being a potential mechanism through which epigenetic factors could regulate gene activity. Such interactions could represent novel mechanisms for important biological functions, including altering nucleosome positioning or regulation of gene expression. Furthermore, promotion of strand-specific G-quadruplex formation in differentially methylated genes could have a dynamic role in directing X-inactivation or the control of imprinting, and would be a worthwhile focus for future research.
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14
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Ma X, Feng Y, Yang Y, Li X, Shi Y, Tao S, Cheng X, Huang J, Wang XE, Chen C, Monchaud D, Zhang W. Genome-wide characterization of i-motifs and their potential roles in the stability and evolution of transposable elements in rice. Nucleic Acids Res 2022; 50:3226-3238. [PMID: 35188565 PMCID: PMC8989525 DOI: 10.1093/nar/gkac121] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 01/13/2022] [Accepted: 02/07/2022] [Indexed: 12/15/2022] Open
Abstract
I-motifs (iMs) are non-canonical DNA secondary structures that fold from cytosine (C)-rich genomic DNA regions termed putative i-motif forming sequences (PiMFSs). The structure of iMs is stabilized by hemiprotonated C-C base pairs, and their functions are now suspected in key cellular processes in human cells such as genome stability and regulation of gene transcription. In plants, their biological relevance is still largely unknown. Here, we characterized PiMFSs with high potential for i-motif formation in the rice genome by developing and applying a protocol hinging on an iMab antibody-based immunoprecipitation (IP) coupled with high-throughput sequencing (seq), consequently termed iM-IP-seq. We found that PiMFSs had intrinsic subgenomic distributions, cis-regulatory functions and an intricate relationship with DNA methylation. We indeed found that the coordination of PiMFSs with DNA methylation may affect dynamics of transposable elements (TEs) among different cultivated Oryza subpopulations or during evolution of wild rice species. Collectively, our study provides first and unique insights into the biology of iMs in plants, with potential applications in plant biotechnology for improving important agronomic rice traits.
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Affiliation(s)
- Xing Ma
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Collaborative Innovation Center for Modern Crop Production co-sponsored by Province and Ministry (CIC-MCP), Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, P.R. China
| | - Yilong Feng
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Collaborative Innovation Center for Modern Crop Production co-sponsored by Province and Ministry (CIC-MCP), Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, P.R. China
| | - Ying Yang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Collaborative Innovation Center for Modern Crop Production co-sponsored by Province and Ministry (CIC-MCP), Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, P.R. China
| | - Xin Li
- Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan410125, P.R. China
| | - Yining Shi
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Collaborative Innovation Center for Modern Crop Production co-sponsored by Province and Ministry (CIC-MCP), Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, P.R. China
| | - Shentong Tao
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Collaborative Innovation Center for Modern Crop Production co-sponsored by Province and Ministry (CIC-MCP), Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, P.R. China
| | - Xuejiao Cheng
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Collaborative Innovation Center for Modern Crop Production co-sponsored by Province and Ministry (CIC-MCP), Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, P.R. China
| | - Jian Huang
- School of Biology & Basic Medical Science, Soochow University, Suzhou, Jiangsu 215123, P.R. China
| | - Xiu-e Wang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Collaborative Innovation Center for Modern Crop Production co-sponsored by Province and Ministry (CIC-MCP), Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, P.R. China
| | - Caiyan Chen
- Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan410125, P.R. China
| | - David Monchaud
- Institut de Chimie Moleculaire, ICMUB CNRS UMR 6302, UBFC Dijon, France
| | - Wenli Zhang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Collaborative Innovation Center for Modern Crop Production co-sponsored by Province and Ministry (CIC-MCP), Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, P.R. China
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15
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Kretzmann JA, Irving KL, Smith NM, Evans CW. Modulating gene expression in breast cancer via DNA secondary structure and the CRISPR toolbox. NAR Cancer 2022; 3:zcab048. [PMID: 34988459 PMCID: PMC8693572 DOI: 10.1093/narcan/zcab048] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 11/26/2021] [Accepted: 12/01/2021] [Indexed: 12/11/2022] Open
Abstract
Breast cancer is the most commonly diagnosed malignancy in women, and while the survival prognosis of patients with early-stage, non-metastatic disease is ∼75%, recurrence poses a significant risk and advanced and/or metastatic breast cancer is incurable. A distinctive feature of advanced breast cancer is an unstable genome and altered gene expression patterns that result in disease heterogeneity. Transcription factors represent a unique therapeutic opportunity in breast cancer, since they are known regulators of gene expression, including gene expression involved in differentiation and cell death, which are themselves often mutated or dysregulated in cancer. While transcription factors have traditionally been viewed as 'undruggable', progress has been made in the development of small-molecule therapeutics to target relevant protein-protein, protein-DNA and enzymatic active sites, with varying levels of success. However, non-traditional approaches such as epigenetic editing, transcriptional control via CRISPR/dCas9 systems, and gene regulation through non-canonical nucleic acid secondary structures represent new directions yet to be fully explored. Here, we discuss these new approaches and current limitations in light of new therapeutic opportunities for breast cancers.
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Affiliation(s)
- Jessica A Kretzmann
- Laboratory for Biomolecular Nanotechnology, Department of Physics, Technical University of Munich, Am Coulombwall 4a, 85748 Garching, Germany
| | - Kelly L Irving
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia
| | - Nicole M Smith
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia
| | - Cameron W Evans
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia
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16
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Novotný A, Novotný J, Kejnovská I, Vorlíčková M, Fiala R, Marek R. Revealing structural peculiarities of homopurine GA repetition stuck by i-motif clip. Nucleic Acids Res 2021; 49:11425-11437. [PMID: 34718718 PMCID: PMC8599794 DOI: 10.1093/nar/gkab915] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 09/17/2021] [Accepted: 09/27/2021] [Indexed: 11/12/2022] Open
Abstract
Non-canonical forms of nucleic acids represent challenging objects for both structure-determination and investigation of their potential role in living systems. In this work, we uncover a structure adopted by GA repetition locked in a parallel homoduplex by an i-motif. A series of DNA oligonucleotides comprising GAGA segment and C3 clip is analyzed by NMR and CD spectroscopies to understand the sequence-structure-stability relationships. We demonstrate how the relative position of the homopurine GAGA segment and the C3 clip as well as single-base mutations (guanine deamination and cytosine methylation) affect base pairing arrangement of purines, i-motif topology and overall stability. We focus on oligonucleotides C3GAGA and methylated GAGAC3 exhibiting the highest stability and structural uniformity which allowed determination of high-resolution structures further analyzed by unbiased molecular dynamics simulation. We describe sequence-specific supramolecular interactions on the junction between homoduplex and i-motif blocks that contribute to the overall stability of the structures. The results show that the distinct structural motifs can not only coexist in the tight neighborhood within the same molecule but even mutually support their formation. Our findings are expected to have general validity and could serve as guides in future structure and stability investigations of nucleic acids.
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Affiliation(s)
- Aleš Novotný
- CEITEC – Central European Institute of Technology, Masaryk University, Kamenice 5, CZ-62500 Brno, Czechia
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, CZ-625 00 Brno, Czechia
| | - Jan Novotný
- CEITEC – Central European Institute of Technology, Masaryk University, Kamenice 5, CZ-62500 Brno, Czechia
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, CZ-625 00 Brno, Czechia
| | - Iva Kejnovská
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, CZ-612 65 Brno, Czechia
| | - Michaela Vorlíčková
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, CZ-612 65 Brno, Czechia
| | - Radovan Fiala
- CEITEC – Central European Institute of Technology, Masaryk University, Kamenice 5, CZ-62500 Brno, Czechia
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, CZ-625 00 Brno, Czechia
| | - Radek Marek
- CEITEC – Central European Institute of Technology, Masaryk University, Kamenice 5, CZ-62500 Brno, Czechia
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, CZ-625 00 Brno, Czechia
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17
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Matsumoto S, Tateishi-Karimata H, Ohyama T, Sugimoto N. Effect of DNA modifications on the transition between canonical and non-canonical DNA structures in CpG islands during senescence. RSC Adv 2021; 11:37205-37217. [PMID: 35496393 PMCID: PMC9043837 DOI: 10.1039/d1ra07201c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 11/08/2021] [Indexed: 12/22/2022] Open
Abstract
Patterns and levels of DNA modifications play important roles in senescence. Two major epigenetic modifications of DNA, 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC), target CpG sites. Importantly, CpG concentrated regions, known as CpG islands, contain GC-rich sequences, which have the potential to fold into non-canonical DNA structures such as i-motifs and G-quadruplexes. In this study, we investigated the effect of 5mC and 5hmC modifications on the transition between a duplex, and i-motif and G-quadruplexes. To examine the transition, we firstly investigated the stability and structure of the i-motif and G-quadruplexes, considering the molecular environment in senescent cells. Analyses of their stability showed that the modifications did not drastically affect the stability. However, noteworthily, the modification can weaken the (de)stabilisation effect on G-quadruplexes caused by cosolute(s) and cations. Circular dichroism analyses indicated that the surrounding environments, including the molecular crowding and the type of cations such as K+ and Na+, regulate the topology of G-quadruplexes, while neither 5mC nor 5hmC had a drastic effect. On the other hand, the modifications changed the transition between duplexes and quadruplexes. Unmodified DNA preferred to fold into quadruplexes, whereas DNA with 5mC and 5hmC preferred to fold into duplexes in the absence of PEG200; on the other hand, DNA with or without modifications tended to fold into i-motifs under crowded conditions. Furthermore, an investigation of quadruplexes forming sequences in CpG islands, which are hyper- or hypomethylated during senescence, followed by gene ontology enrichment analysis for each gene group classified by the presence of quadruplexes, showed a difference in function between genes with and without quadruplexes in the CpG region. These results indicate that it is important to consider the effects of patterns and levels of DNA modifications on the transition between canonical and non-canonical DNA structures to understand gene regulation by epigenetic modification during senescence. The modification of DNA can regulate the transition between a duplex and quadruplexes during senescence responding to surrounding environments.![]()
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Affiliation(s)
- Saki Matsumoto
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University 7-1-20 Minatojima-minamimachi Kobe 650-0047 Japan
| | - Hisae Tateishi-Karimata
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University 7-1-20 Minatojima-minamimachi Kobe 650-0047 Japan
| | - Tatsuya Ohyama
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University 7-1-20 Minatojima-minamimachi Kobe 650-0047 Japan
| | - Naoki Sugimoto
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University 7-1-20 Minatojima-minamimachi Kobe 650-0047 Japan .,Graduate School of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University 7-1-20 Minatojima-minamimachi Kobe 650-0047 Japan
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18
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Balasubramaniyam T, Oh KI, Jin HS, Ahn HB, Kim BS, Lee JH. Non-Canonical Helical Structure of Nucleic Acids Containing Base-Modified Nucleotides. Int J Mol Sci 2021; 22:9552. [PMID: 34502459 PMCID: PMC8430589 DOI: 10.3390/ijms22179552] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 08/27/2021] [Accepted: 08/29/2021] [Indexed: 12/12/2022] Open
Abstract
Chemically modified nucleobases are thought to be important for therapeutic purposes as well as diagnosing genetic diseases and have been widely involved in research fields such as molecular biology and biochemical studies. Many artificially modified nucleobases, such as methyl, halogen, and aryl modifications of purines at the C8 position and pyrimidines at the C5 position, are widely studied for their biological functions. DNA containing these modified nucleobases can form non-canonical helical structures such as Z-DNA, G-quadruplex, i-motif, and triplex. This review summarizes the synthesis of chemically modified nucleotides: (i) methylation, bromination, and arylation of purine at the C8 position and (ii) methylation, bromination, and arylation of pyrimidine at the C5 position. Additionally, we introduce the non-canonical structures of nucleic acids containing these modifications.
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Affiliation(s)
- Thananjeyan Balasubramaniyam
- Department of Chemistry, Gyeongsang National University, Jinju 52828, Gyeongnam, Korea; (T.B.); (K.-I.O.); (H.-S.J.); (H.-B.A.)
- The Research Institute of Natural Science, Gyeongsang National University, Jinju 52828, Gyeongnam, Korea
| | - Kwnag-Im Oh
- Department of Chemistry, Gyeongsang National University, Jinju 52828, Gyeongnam, Korea; (T.B.); (K.-I.O.); (H.-S.J.); (H.-B.A.)
- The Research Institute of Natural Science, Gyeongsang National University, Jinju 52828, Gyeongnam, Korea
| | - Ho-Seong Jin
- Department of Chemistry, Gyeongsang National University, Jinju 52828, Gyeongnam, Korea; (T.B.); (K.-I.O.); (H.-S.J.); (H.-B.A.)
| | - Hye-Bin Ahn
- Department of Chemistry, Gyeongsang National University, Jinju 52828, Gyeongnam, Korea; (T.B.); (K.-I.O.); (H.-S.J.); (H.-B.A.)
| | - Byeong-Seon Kim
- The Research Institute of Natural Science, Gyeongsang National University, Jinju 52828, Gyeongnam, Korea
- Department of Chemistry Education, Gyeongsang National University, Jinju 52828, Gyeongnam, Korea
| | - Joon-Hwa Lee
- Department of Chemistry, Gyeongsang National University, Jinju 52828, Gyeongnam, Korea; (T.B.); (K.-I.O.); (H.-S.J.); (H.-B.A.)
- The Research Institute of Natural Science, Gyeongsang National University, Jinju 52828, Gyeongnam, Korea
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19
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Seidu YS, Roy HA, Rodgers MT. Influence of 5-Methylation and the 2'- and 3'-Hydroxy Substituents on the Base Pairing Energies of Protonated Cytidine Nucleoside Analogue Base Pairs: Implications for the Stabilities of i-Motif Structures. J Phys Chem A 2021; 125:5939-5955. [PMID: 34228469 DOI: 10.1021/acs.jpca.1c04303] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Repetitive nucleic acid sequences, which occur in abundance throughout the mammalian genome, are of enormous research interest due to their potential to adopt fascinating and unusual molecular structures such as the i-motif. In remarkable contrast to the DNA double helix, i-motif conformations are stabilized by protonated cytosine base pairs, (Cyt)H+(Cyt), that are centrally located in the core of the i-motif and intercalated vertically in an antiparallel fashion. An in-depth understanding of how modifications influence the stability of i-motif conformations is a prerequisite to understanding their biological functions and the development of effective means of tuning their stability for specific medical and technological applications. Here, the influence of the 2'- and 3'-hydroxy substituents of the sugar moieties and 5-methylation of the cytosine nucleobases on the base-pairing interactions of protonated cytidine nucleoside analogue base pairs, (xCyd)H+(xCyd), are examined by complementary threshold collision-induced dissociation techniques and computational methods. The xCyd nucleosides examined include the canonical DNA and RNA cytidine nucleosides, 2'-deoxycytidine (dCyd) and cytidine (Cyd), as well as several modified cytidine nucleoside analogues, 2',3'-dideoxycytidine (ddCyd), 5-methyl-2'-deoxycytidine (m5dCyd), and 5-methylcytidine (m5Cyd). Comparisons among these model base pairs indicate that the 2'- and 3'-hydroxy substituents of the sugar moieties have very little influence on the strength of the base-pairing interactions, whereas 5-methylation of the cytosine nucleobases is found to enhance the strength of the base-pairing interactions. The increase in stability resulting from 5-methylation is only modest but is more than twice as large for the DNA than RNA protonated cytidine base pair. Overall, present results suggest that canonical DNA i-motif conformations should be more stable than analogous RNA i-motif conformations and that 5-methylation of cytosine residues, a significant epigenetic marker, provides greater stabilization to DNA than RNA i-motif conformations.
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Affiliation(s)
- Yakubu S Seidu
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | - H A Roy
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | - M T Rodgers
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
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20
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Wan L, Yi J, Lam SL, Lee HK, Guo P. 5-Methylcytosine Substantially Enhances the Thermal Stability of DNA Minidumbbells. Chemistry 2021; 27:6740-6747. [PMID: 33501691 DOI: 10.1002/chem.202005410] [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: 12/20/2020] [Indexed: 11/07/2022]
Abstract
Minidumbbell (MDB) is a recently identified non-B DNA structure that has been proposed to associate with genetic instabilities. It also serves as a functional structural motif in DNA nanotechnology. DNA molecular switches constructed using MDBs show instant and complete structural conversions with easy manipulations. The availability of stable MDBs can broaden their applications. In this work, we found that substitutions of cytosine with 5-methylcytosine could lead to a significant enhancement in the thermal stabilities of MDBs. Consecutive methylations of cytosine in MDBs brought about cumulative stabilization with a drastic increase in the melting temperature by 23 °C. NMR solution structures of two MDBs containing 5-methylcytosine residues have been successfully determined and revealed that the enhanced stabilities resulted primarily from favorable hydrophobic contacts, more stable base pairs and enhanced base-base stackings involving the methyl group of 5-methylcytosine.
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Affiliation(s)
- Liqi Wan
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China
| | - Jie Yi
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, Guangdong, 510006, China
| | - Sik Lok Lam
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China
| | - Hung Kay Lee
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China
| | - Pei Guo
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, Guangdong, 510006, China
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21
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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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22
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Tsuruta M, Sugitani Y, Sugimoto N, Miyoshi D. Combined Effects of Methylated Cytosine and Molecular Crowding on the Thermodynamic Stability of DNA Duplexes. Int J Mol Sci 2021; 22:ijms22020947. [PMID: 33477917 PMCID: PMC7833394 DOI: 10.3390/ijms22020947] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 01/14/2021] [Accepted: 01/15/2021] [Indexed: 12/31/2022] Open
Abstract
Methylated cytosine within CpG dinucleotides is a key factor for epigenetic gene regulation. It has been revealed that methylated cytosine decreases DNA backbone flexibility and increases the thermal stability of DNA. Although the molecular environment is an important factor for the structure, thermodynamics, and function of biomolecules, there are few reports on the effects of methylated cytosine under a cell-mimicking molecular environment. Here, we systematically investigated the effects of methylated cytosine on the thermodynamics of DNA duplexes under molecular crowding conditions, which is a critical difference between the molecular environment in cells and test tubes. Thermodynamic parameters quantitatively demonstrated that the methylation effect and molecular crowding effect on DNA duplexes are independent and additive, in which the degree of the stabilization is the sum of the methylation effect and molecular crowding effect. Furthermore, the effects of methylation and molecular crowding correlate with the hydration states of DNA duplexes. The stabilization effect of methylation was due to the favorable enthalpic contribution, suggesting that direct interactions of the methyl group with adjacent bases and adjacent methyl groups play a role in determining the flexibility and thermodynamics of DNA duplexes. These results are useful to predict the properties of DNA duplexes with methylation in cell-mimicking conditions.
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Affiliation(s)
- Mitsuki Tsuruta
- Faculty of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, Kobe 650-0047, Japan; (M.T.); (Y.S.); (N.S.)
| | - Yui Sugitani
- Faculty of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, Kobe 650-0047, Japan; (M.T.); (Y.S.); (N.S.)
| | - Naoki Sugimoto
- Faculty of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, Kobe 650-0047, Japan; (M.T.); (Y.S.); (N.S.)
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, Kobe 650-0047, Japan
| | - Daisuke Miyoshi
- Faculty of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, Kobe 650-0047, Japan; (M.T.); (Y.S.); (N.S.)
- Correspondence: ; Tel.: +81-(07)-8303-1426
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23
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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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24
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Sanchez-Martin V, Lopez-Pujante C, Soriano-Rodriguez M, Garcia-Salcedo JA. An Updated Focus on Quadruplex Structures as Potential Therapeutic Targets in Cancer. Int J Mol Sci 2020; 21:ijms21238900. [PMID: 33255335 PMCID: PMC7734589 DOI: 10.3390/ijms21238900] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 11/13/2020] [Accepted: 11/20/2020] [Indexed: 02/06/2023] Open
Abstract
Non-canonical, four-stranded nucleic acids secondary structures are present within regulatory regions in the human genome and transcriptome. To date, these quadruplex structures include both DNA and RNA G-quadruplexes, formed in guanine-rich sequences, and i-Motifs, found in cytosine-rich sequences, as their counterparts. Quadruplexes have been extensively associated with cancer, playing an important role in telomere maintenance and control of genetic expression of several oncogenes and tumor suppressors. Therefore, quadruplex structures are considered attractive molecular targets for cancer therapeutics with novel mechanisms of action. In this review, we provide a general overview about recent research on the implications of quadruplex structures in cancer, firstly gathering together DNA G-quadruplexes, RNA G-quadruplexes as well as DNA i-Motifs.
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Affiliation(s)
- Victoria Sanchez-Martin
- GENYO, Centre for Genomics and Oncological Research, Pfizer/University of Granada/Andalusian Regional Government, PTS Granada, 18016 Granada, Spain; (V.S.-M.); (C.L.-P.)
- Microbiology Unit, University Hospital Virgen de las Nieves, Biosanitary Research Institute IBS, Granada, 18014 Granada, Spain
- Department of Biochemistry, Molecular Biology III and Immunology, University of Granada, 18016 Granada, Spain
| | - Carmen Lopez-Pujante
- GENYO, Centre for Genomics and Oncological Research, Pfizer/University of Granada/Andalusian Regional Government, PTS Granada, 18016 Granada, Spain; (V.S.-M.); (C.L.-P.)
| | - Miguel Soriano-Rodriguez
- GENYO, Centre for Genomics and Oncological Research, Pfizer/University of Granada/Andalusian Regional Government, PTS Granada, 18016 Granada, Spain; (V.S.-M.); (C.L.-P.)
- Centre for Intensive Mediterranean Agrosystems and Agri-food Biotechnology (CIAMBITAL), University of Almeria, 04001 Almeria, Spain
- Correspondence: (M.S.-R.); (J.A.G.-S.); Tel.: +34-958715500 (M.S.-R.); +34-958715500 (J.A.G.-S.)
| | - Jose A. Garcia-Salcedo
- GENYO, Centre for Genomics and Oncological Research, Pfizer/University of Granada/Andalusian Regional Government, PTS Granada, 18016 Granada, Spain; (V.S.-M.); (C.L.-P.)
- Microbiology Unit, University Hospital Virgen de las Nieves, Biosanitary Research Institute IBS, Granada, 18014 Granada, Spain
- Correspondence: (M.S.-R.); (J.A.G.-S.); Tel.: +34-958715500 (M.S.-R.); +34-958715500 (J.A.G.-S.)
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Školáková P, Badri Z, Foldynová-Trantírková S, Ryneš J, Šponer J, Fojtová M, Fajkus J, Marek R, Vorlíčková M, Mergny JL, Trantírek L. Composite 5-methylations of cytosines modulate i-motif stability in a sequence-specific manner: Implications for DNA nanotechnology and epigenetic regulation of plant telomeric DNA. Biochim Biophys Acta Gen Subj 2020; 1864:129651. [DOI: 10.1016/j.bbagen.2020.129651] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 05/23/2020] [Accepted: 05/28/2020] [Indexed: 12/14/2022]
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26
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Wright EP, Abdelhamid MAS, Ehiabor MO, Grigg MC, Irving K, Smith NM, Waller ZAE. Epigenetic modification of cytosines fine tunes the stability of i-motif DNA. Nucleic Acids Res 2020; 48:55-62. [PMID: 31777919 PMCID: PMC6943138 DOI: 10.1093/nar/gkz1082] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 10/29/2019] [Accepted: 11/25/2019] [Indexed: 01/17/2023] Open
Abstract
i-Motifs are widely used in nanotechnology, play a part in gene regulation and have been detected in human nuclei. As these structures are composed of cytosine, they are potential sites for epigenetic modification. In addition to 5-methyl- and 5-hydroxymethylcytosine modifications, recent evidence has suggested biological roles for 5-formylcytosine and 5-carboxylcytosine. Herein the human telomeric i-motif sequence was used to examine how these four epigenetic modifications alter the thermal and pH stability of i-motifs. Changes in melting temperature and transitional pH depended on both the type of modification and its position within the i-motif forming sequence. The cytosines most sensitive to modification were next to the first and third loops within the structure. Using previously described i-motif forming sequences, we screened the MCF-7 and MCF-10A methylomes to map 5-methylcytosine and found the majority of sequences were differentially methylated in MCF7 (cancerous) and MCF10A (non-cancerous) cell lines. Furthermore, i-motif forming sequences stable at neutral pH were significantly more likely to be epigenetically modified than traditional acidic i-motif forming sequences. This work has implications not only in the epigenetic regulation of DNA, but also allows discreet tunability of i-motif stability for nanotechnological applications.
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Affiliation(s)
- Elisé P Wright
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Mahmoud A S Abdelhamid
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.,Centre for Molecular and Structural Biochemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Michelle O Ehiabor
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Melanie C Grigg
- School of Molecular Sciences, University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia
| | - Kelly Irving
- School of Molecular Sciences, University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia
| | - Nicole M Smith
- School of Molecular Sciences, University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia
| | - Zoë A E Waller
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.,Centre for Molecular and Structural Biochemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
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27
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Abdelhamid MAS, Waller ZAE. Tricky Topology: Persistence of Folded Human Telomeric i-Motif DNA at Ambient Temperature and Neutral pH. Front Chem 2020; 8:40. [PMID: 32083057 PMCID: PMC7005205 DOI: 10.3389/fchem.2020.00040] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 01/14/2020] [Indexed: 12/30/2022] Open
Abstract
i-Motifs are four-stranded DNA structures formed from sequences rich in cytosine, held together by hemi-protonated cytosine-cytosine base pairs. These structures have been utilized extensively as pH-switches in DNA-based nanotechnology. Recently there has been an increasing interest in i-motif structures in biology, fuelled by examples of when these can form under neutral conditions. Herein we describe a cautionary tale regarding handling of i-motif samples. Using CD and UV spectroscopy we show that it is important to be consistent in annealing i-motif DNA samples as at neutral pH, i-motif unfolding kinetics is dependent on the time allowed for annealing and equilibration. We describe how the quadruplex structure formed by the human telomeric i-motif sequence can be shown to form and persist in the same conditions of neutral pH and ambient temperature in which, once at thermodynamic equilibrium, it exists predominantly as a random coil. This study has implications not only for work with i-motif DNA structures, but also in the uses and applications of these in nanotechnological devices.
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Affiliation(s)
- Mahmoud A S Abdelhamid
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich, United Kingdom.,Centre for Molecular and Structural Biochemistry, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
| | - Zoë A E Waller
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich, United Kingdom.,Centre for Molecular and Structural Biochemistry, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
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28
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Devaux A, Bonnat L, Lavergne T, Defrancq E. Access to a stabilized i-motif DNA structure through four successive ligation reactions on a cyclopeptide scaffold. Org Biomol Chem 2020; 18:6394-6406. [DOI: 10.1039/d0ob01311k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Four successive chemical ligations were used for the assembly of a sophisticated biomolecular system allowing the formation of a stabilized i-motif DNA at pH 7.
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Affiliation(s)
- Alexandre Devaux
- Univ. Grenoble Alpes
- Département de Chimie Moléculaire
- CNRS
- Grenoble 38000
- France
| | - Laureen Bonnat
- Univ. Grenoble Alpes
- Département de Chimie Moléculaire
- CNRS
- Grenoble 38000
- France
| | - Thomas Lavergne
- Univ. Grenoble Alpes
- Département de Chimie Moléculaire
- CNRS
- Grenoble 38000
- France
| | - Eric Defrancq
- Univ. Grenoble Alpes
- Département de Chimie Moléculaire
- CNRS
- Grenoble 38000
- France
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29
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Dvoráková Z, Renciuk D, Kejnovská I, Školáková P, Bednárová K, Sagi J, Vorlícková M. i-Motif of cytosine-rich human telomere DNA fragments containing natural base lesions. Nucleic Acids Res 2019; 46:1624-1634. [PMID: 29378012 PMCID: PMC5829569 DOI: 10.1093/nar/gky035] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 01/15/2018] [Indexed: 12/01/2022] Open
Abstract
i-Motif (iM) is a four stranded DNA structure formed by cytosine-rich sequences, which are often present in functionally important parts of the genome such as promoters of genes and telomeres. Using electronic circular dichroism and UV absorption spectroscopies and electrophoretic methods, we examined the effect of four naturally occurring DNA base lesions on the folding and stability of the iM formed by the human telomere DNA sequence (C3TAA)3C3T. The results demonstrate that the TAA loop lesions, the apurinic site and 8-oxoadenine substituting for adenine, and the 5-hydroxymethyluracil substituting for thymine only marginally disturb the formation of iM. The presence of uracil, which is formed by enzymatic or spontaneous deamination of cytosine, shifts iM formation towards substantially more acidic pH values and simultaneously distinctly reduces iM stability. This effect depends on the position of the damage sites in the sequence. The results have enabled us to formulate additional rules for iM formation.
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Affiliation(s)
- Zuzana Dvoráková
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic
| | - Daniel Renciuk
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic
| | - Iva Kejnovská
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic
| | - Petra Školáková
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic
| | - Klára Bednárová
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic
| | - Janos Sagi
- Rimstone Laboratory, RLI, Carlsbad, CA 92010, USA
| | - Michaela Vorlícková
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic
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30
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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: 236] [Impact Index Per Article: 47.2] [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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31
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Todorov G, Cunha C. Hypothesis: Regulation of neuroplasticity may involve I-motif and G-quadruplex DNA formation modulated by epigenetic mechanisms. Med Hypotheses 2019; 127:129-135. [PMID: 31088636 DOI: 10.1016/j.mehy.2019.04.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 04/04/2019] [Accepted: 04/08/2019] [Indexed: 01/12/2023]
Abstract
Recent studies demonstrated the existence in vivo of various functional DNA structures that differ from the double helix. The G-quadruplex (G4) and intercalated motif (I-motif or IM) DNA structures are formed as knots where, correspondingly, guanines or cytosines on the same strand of DNA bind to each other. There are grounds to believe that G4 and IM sequences play a significant role in regulating gene expression considering their tendency to be found in or near regulatory sites (such as promoters, enhancers, and telomeres) as well as the correlation between the prevalence of G4 or IM conformations and specific phases of cell cycle. Notably, G4 and IM capable sequences tend to be found on the opposite strands of the same DNA site with at most one of the two structures formed at any given time. The recent evidence that K+, Mg2+ concentrations directly affect IM formation (and likely G4 formation indirectly) lead us to believe that these structures may play a major role in synaptic plasticity of neurons, and, therefore, in a variety of central nervous system (CNS) functions including memory, learning, habitual behaviors, pain perception and others. Furthermore, epigenetic mechanisms, which have an important role in synaptic plasticity and memory formation, were also shown to influence formation and stability of G4s and IMs. Our hypothesis is that non-canonical DNA and RNA structures could be an integral part of neuroplasticity control via gene expression regulation at the level of transcription, translation and splicing. We propose that the regulatory activity of DNA IM and G4 structures is modulated by DNA methylation/demethylation of the IM and/or G4 sequences, which facilitates the switch between canonical and non-canonical conformation. Other neuronal mechanisms interacting with the formation and regulatory activity of non-canonical DNA and RNA structures, particularly G4, IM and triplexes, may involve microRNAs as well as ion and proton fluxes. We are proposing experiments in acute brain slices and in vivo to test our hypothesis. The proposed studies would provide new insights into fundamental neuronal mechanisms in health and disease and potentially open new avenues for treating mental health disorders.
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Affiliation(s)
- German Todorov
- Emotional Brain Institute, Nathan Kline Institute, Orangeburg, NY, USA
| | - Catarina Cunha
- Emotional Brain Institute, Nathan Kline Institute, Orangeburg, NY, USA.
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32
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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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33
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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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34
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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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35
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Rogers RA, Fleming AM, Burrows CJ. Rapid Screen of Potential i-Motif Forming Sequences in DNA Repair Gene Promoters. ACS OMEGA 2018; 3:9630-9635. [PMID: 30198001 PMCID: PMC6120732 DOI: 10.1021/acsomega.8b01551] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 08/08/2018] [Indexed: 06/08/2023]
Abstract
We have studied the in vitro stability of 25 potential i-motif-forming DNA sequences found within the promoter regions of 18 different human DNA repair genes. Three widely available methods of characterization were used to rapidly assess i-motif folding and stability and comprise a simple screen for preliminary identification of physiologically relevant i-motif forming sequences. Four highly pH-stable candidate sequences were identified exhibiting pH transitions (pH at which 50% of the oligodeoxynucleotides in solution are folded) at or above pH 6.6, thermal melting temperatures above 37 °C and isothermal UV difference spectra characteristic of 2'-deoxycytidine imino-nitrogen protonation. These newly identified i-motif forming sequences could represent novel targets for understanding and modulating human DNA repair gene expression.
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36
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González-Olvera JC, Durec M, Marek R, Fiala R, Morales-García MDRJ, González-Jasso E, Pless RC. Protonation of Nucleobases in Single- and Double-Stranded DNA. Chembiochem 2018; 19:2088-2098. [PMID: 30073767 DOI: 10.1002/cbic.201800310] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Indexed: 01/05/2023]
Abstract
Single-stranded model oligodeoxyribonucleotides, each containing a single protonatable base-cytosine, adenine, guanine, or 5-methylcytosine-centrally located in a background of non-protonatable thymine residues, were acid-titrated in aqueous solution, with UV monitoring. The basicity of the central base was shown to depend on the type of the central base and its nearest neighbours and to rise with increasing oligonucleotide length and decreasing ionic strength of the solution. More complex model oligonucleotides, each containing a centrally located 5-methylcytosine base, were comparatively evaluated in single-stranded and double-stranded form, by UV spectroscopy and high-field NMR. The N3 protonation of the 5-methylcytosine moiety in the double-stranded case occurred at much lower pH, at which the duplex was already experiencing general dissociation, than in the single-stranded case. The central guanine:5-methylcytosine base pair remained intact up to this point, possibly due to an unusual alternative protonation on O2 of the 5-methylcytosine moiety, already taking place at neutral or weakly basic pH, as indicated by UV spectroscopy, thus suggesting that 5-methylcytosine sites in double-stranded DNA might be protonated to a significant extent under physiological conditions.
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Affiliation(s)
- Julio C González-Olvera
- Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Instituto Politécnico Nacional, Querétaro, Querétaro, 76090, Mexico.,Universidad Politécnica de Santa Rosa Jáuregui, Santa Rosa Jáuregui, Querétaro, 76220, Mexico
| | - Matúš Durec
- CEITEC-Central European Institute of Technology, Masaryk University, Kamenice 753/5, 62500, Brno, Czech Republic
| | - Radek Marek
- CEITEC-Central European Institute of Technology, Masaryk University, Kamenice 753/5, 62500, Brno, Czech Republic
| | - Radovan Fiala
- CEITEC-Central European Institute of Technology, Masaryk University, Kamenice 753/5, 62500, Brno, Czech Republic
| | | | - Eva González-Jasso
- Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Instituto Politécnico Nacional, Querétaro, Querétaro, 76090, Mexico
| | - Reynaldo C Pless
- Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Instituto Politécnico Nacional, Querétaro, Querétaro, 76090, Mexico
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37
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Pagano A, Iaccarino N, Abdelhamid MAS, Brancaccio D, Garzarella EU, Di Porzio A, Novellino E, Waller ZAE, Pagano B, Amato J, Randazzo A. Common G-Quadruplex Binding Agents Found to Interact With i-Motif-Forming DNA: Unexpected Multi-Target-Directed Compounds. Front Chem 2018; 6:281. [PMID: 30137743 PMCID: PMC6066642 DOI: 10.3389/fchem.2018.00281] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 06/22/2018] [Indexed: 11/26/2022] Open
Abstract
G-quadruplex (G4) and i-motif (iM) are four-stranded non-canonical nucleic acid structural arrangements. Recent evidences suggest that these DNA structures exist in living cells and could be involved in several cancer-related processes, thus representing an attractive target for anticancer drug discovery. Efforts toward the development of G4 targeting compounds have led to a number of effective bioactive ligands. Herein, employing several biophysical methodologies, we studied the ability of some well-known G4 ligands to interact with iM-forming DNA. The data showed that the investigated compounds are actually able to interact with both DNA in vitro, thus acting de facto as multi-target-directed agents. Interestingly, while all the compounds stabilize the G4, some of them significantly reduce the stability of the iM. The present study highlights the importance, when studying G4-targeting compounds, of evaluating also their behavior toward the i-motif counterpart.
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Affiliation(s)
- Alessia Pagano
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - Nunzia Iaccarino
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - Mahmoud A S Abdelhamid
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
| | - Diego Brancaccio
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | | | - Anna Di Porzio
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - Ettore Novellino
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - Zoë A E Waller
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich, United Kingdom.,Centre for Molecular and Structural Biochemistry, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
| | - Bruno Pagano
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - Jussara Amato
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - Antonio Randazzo
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
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38
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I-motif DNA structures are formed in the nuclei of human cells. Nat Chem 2018; 10:631-637. [PMID: 29686376 DOI: 10.1038/s41557-018-0046-3] [Citation(s) in RCA: 344] [Impact Index Per Article: 57.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 03/14/2018] [Indexed: 12/25/2022]
Abstract
Human genome function is underpinned by the primary storage of genetic information in canonical B-form DNA, with a second layer of DNA structure providing regulatory control. I-motif structures are thought to form in cytosine-rich regions of the genome and to have regulatory functions; however, in vivo evidence for the existence of such structures has so far remained elusive. Here we report the generation and characterization of an antibody fragment (iMab) that recognizes i-motif structures with high selectivity and affinity, enabling the detection of i-motifs in the nuclei of human cells. We demonstrate that the in vivo formation of such structures is cell-cycle and pH dependent. Furthermore, we provide evidence that i-motif structures are formed in regulatory regions of the human genome, including promoters and telomeric regions. Our results support the notion that i-motif structures provide key regulatory roles in the genome.
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39
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Tanaka S, Yukami S, Fukushima K, Wakabayashi K, Ohya Y, Kuzuya A. Bulk pH-Responsive DNA Quadruplex Hydrogels Prepared by Liquid-Phase, Large-Scale DNA Synthesis. ACS Macro Lett 2018; 7:295-299. [PMID: 35632920 DOI: 10.1021/acsmacrolett.8b00063] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A new pH-responsive hydrogel biomaterial, that is composed of solely two popular biocompatible materials, oligodeoxynucleotides (ODN) and polyethylene glycol (PEG) have been prepared. Merely five deoxycytidine residues were elongated to the ends of linear or 4-arm PEG in ×1000 larger scale than conventional systems by using liquid-phase DNA synthesis technique, and applied them as a macromonomer for the preparation of hydrogels. The syntheses of the conjugates are simply elongating ODN onto the ends of PEG as a semisolid phase substrate using standard phosphoramidite chemistry. The resulting dC5-PEG conjugates gave quite stable and stiff hydrogels triggered by the formation of a unique DNA quadruplex, i-motif. Introduction of only one chemical linkage between two linear conjugates resulted in unexpectedly high thermal stabilities for the melting temperatures of i-motifs themselves. Nonlinearly improved rheological properties compared to the original linear conjugates were also observed, probably because of topological entanglement between macromonomers of fused circles.
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40
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Abou Assi H, Lin YC, Serrano I, González C, Damha MJ. Probing Synergistic Effects of DNA Methylation and 2′-β-Fluorination on i-Motif Stability. Chemistry 2017; 24:471-477. [PMID: 29096420 DOI: 10.1002/chem.201704591] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Indexed: 12/12/2022]
Affiliation(s)
- Hala Abou Assi
- Department of Chemistry; McGill University; 801 Sherbrooke St. West Montreal QC H3A 0B8 Canada
| | - Yu Chen Lin
- Department of Chemistry; McGill University; 801 Sherbrooke St. West Montreal QC H3A 0B8 Canada
| | - Israel Serrano
- Instituto de Química Física “Rocasolano”; CSIC; Serrano 119 28006 Madrid Spain
| | - Carlos González
- Instituto de Química Física “Rocasolano”; CSIC; Serrano 119 28006 Madrid Spain
| | - Masad J. Damha
- Department of Chemistry; McGill University; 801 Sherbrooke St. West Montreal QC H3A 0B8 Canada
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41
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Wright EP, Lamparska K, Smith SS, Waller ZAE. Substitution of Cytosine with Guanylurea Decreases the Stability of i-Motif DNA. Biochemistry 2017; 56:4879-4883. [PMID: 28853563 DOI: 10.1021/acs.biochem.7b00628] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Both 5-aza-2'-deoxycytidine (decitabine) and its primary breakdown product, 2'-deoxyriboguanylurea (GuaUre-dR), have been shown to act as mutagens and epimutagens that cause replication stress and alter both DNA methylation and gene expression patterns. As cytosine analogues, both are expected to be preferentially incorporated into regions of GC skew where runs of cytosine residues are sequestered on one strand and guanine residues on the other. Given that such regions have been identified as sites with the potential for effects on gene expression and replication stress linked to formation of alternative DNA secondary structures, it is of interest to determine the influence that these base analogues might have on the stability of structures of this kind. Here we report that incorporation of GuaUre-dR into an i-motif-forming sequence decreases both the thermal and pH stability of an i-motif despite the apparent ability of GuaUre-dR to base pair with cytosine.
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Affiliation(s)
- Elisé P Wright
- School of Pharmacy, University of East Anglia , Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Katarzyna Lamparska
- Beckman Research Institute and Division of Urology, City of Hope , 1500 East Duarte Road, Duarte, California 91010-3000, United States
| | - Steven S Smith
- Beckman Research Institute and Division of Urology, City of Hope , 1500 East Duarte Road, Duarte, California 91010-3000, United States
| | - Zoë A E Waller
- School of Pharmacy, University of East Anglia , Norwich Research Park, Norwich NR4 7TJ, U.K.,Centre for Molecular and Structural Biochemistry, University of East Anglia , Norwich Research Park, Norwich NR4 7TJ, U.K
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42
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Riml C, Lusser A, Ennifar E, Micura R. Synthesis, Thermodynamic Properties, and Crystal Structure of RNA Oligonucleotides Containing 5-Hydroxymethylcytosine. J Org Chem 2017; 82:7939-7945. [PMID: 28707898 DOI: 10.1021/acs.joc.7b01171] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
5-Hydroxymethylcytosine (hm5C) is an RNA modification that has attracted significant interest because of the finding that RNA hydroxymethylation can favor mRNA translation. For insight into the mechanistic details of hm5C function to be obtained, the availability of RNAs containing this modification at defined positions that can be used for in vitro studies is highly desirable. In this work, we present an eight-step route to 5-hydroxymethylcytidine (hm5rC) phosphoramidite for solid-phase synthesis of modified RNA oligonucleotides. Furthermore, we examined the effects of hm5rC on RNA duplex stability and its impact on structure formation using the sarcin-ricin loop (SRL) motif. Thermal denaturation experiments revealed that hm5rC increases RNA duplex stability. By contrast, when cytosine within an UNCG tetraloop motif was replaced by hm5rC, the thermodynamic stability of the corresponding hairpin fold was attenuated. Importantly, incorporation of hm5rC into the SRL motif resulted in an RNA crystal structure at 0.85 Å resolution. Besides changes in the hydration pattern at the site of modification, a slight opening of the hm5rC-G pair compared to the unmodified C-G in the native structure was revealed.
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Affiliation(s)
- Christian Riml
- Institute of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck , 6020 Innsbruck, Austria
| | - Alexandra Lusser
- Division of Molecular Biology, Biocenter, Medical University of Innsbruck , 6020 Innsbruck, Austria
| | - Eric Ennifar
- Université de Strasbourg, CNRS , Architecture et Réactivité des ARN, UPR 9002, 67000 Strasbourg, France
| | - Ronald Micura
- Institute of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck , 6020 Innsbruck, Austria
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43
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Mir B, Solés X, González C, Escaja N. The effect of the neutral cytidine protonated analogue pseudoisocytidine on the stability of i-motif structures. Sci Rep 2017; 7:2772. [PMID: 28584239 PMCID: PMC5459817 DOI: 10.1038/s41598-017-02723-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 04/05/2017] [Indexed: 01/07/2023] Open
Abstract
Incorporation of pseudoisocytidine (psC), a neutral analogue of protonated cytidine, in i-motifs has been studied by spectroscopic methods. Our results show that neutral psC:C base pairs can stabilize i-motifs at neutral pH, but the stabilization only occurs when psC:C base pairs are located at the ends of intercalated C:C+ stacks. When psC occupies central positions, the resulting i-motifs are only observed at low pH and psC:C+ or psC:psC+ hemiprotonated base pairs are formed instead of their neutral analogs. Overall, our results suggest that positively charged base pairs are necessary to stabilize this non-canonical DNA structure.
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Affiliation(s)
- B Mir
- Inorganic and Organic Chemistry Department, Organic Chemistry Section, and IBUB, University of Barcelona, Martí i Franquès 1-11, 08028, Barcelona, Spain
| | - X Solés
- Inorganic and Organic Chemistry Department, Organic Chemistry Section, and IBUB, University of Barcelona, Martí i Franquès 1-11, 08028, Barcelona, Spain
| | - C González
- Instituto de Química Física Rocasolano, CSIC, Serrano 119, 28006, Madrid, Spain. .,BIOESTRAN, associated unit UB-CSIC, Spain.
| | - N Escaja
- Inorganic and Organic Chemistry Department, Organic Chemistry Section, and IBUB, University of Barcelona, Martí i Franquès 1-11, 08028, Barcelona, Spain. .,BIOESTRAN, associated unit UB-CSIC, Spain.
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44
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Aviñó A, Dellafiore M, Gargallo R, González C, Iribarren AM, Montserrat J, Eritja R. Stabilization of Telomeric I-Motif Structures by (2'S)-2'-Deoxy-2'-C-Methylcytidine Residues. Chembiochem 2017; 18:1123-1128. [PMID: 28407336 DOI: 10.1002/cbic.201700112] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Indexed: 01/12/2023]
Abstract
G-quadruplexes and i-motifs are tetraplex structures present in telomeres and the promoter regions of oncogenes. The possibility of producing nanodevices with pH-sensitive functions has triggered interest in modified oligonucleotides with improved structural properties. We synthesized C-rich oligonucleotides carrying conformationally restricted (2'S)-2'-deoxy-2'-C-methyl-cytidine units. The effect of this modified nucleoside on the stability of intramolecular i-motifs from the vertebrate telomere was investigated by UV, CD, and NMR spectroscopy. The replacement of selected positions of the C-core with C-modified residues induced the formation of stable intercalated tetraplexes at near-neutral pH. This study demonstrates the possibility of enhancing the stability of the i-motif by chemical modification.
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Affiliation(s)
- Anna Aviñó
- Institute for Advanced Chemistry of Catalonia (IQAC), Spanish Council for Scientific Research (CSIC), Jordi Girona 18-26, 08034, Barcelona, Spain.,Networking Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN)
| | - María Dellafiore
- INGEBI (CONICET), Vuelta de Obligado 2490-(1428), Buenos Aires, Argentina
| | - Raimundo Gargallo
- Department of Chemical Engineering and Analytical Chemistry, University of Barcelona, Martí i Franquès, 1-11, 08028, Barcelona, Spain.,BIOESTRAN, Associated Unit UB-CSIC
| | - Carlos González
- BIOESTRAN, Associated Unit UB-CSIC.,Institute of Physical Chemistry Rocasolano (IQFR), Spanish Council for Scientific Research (CSIC), Serrano 119, 28006, Madrid, Spain
| | - Adolfo M Iribarren
- CONICET. Laboratorio de Biotransformaciones, Universidad Nacional de Quilmes, Roque Saenz Peña 352 (1876) Bernal, Prov. de Buenos Aires, Argentina
| | - Javier Montserrat
- CONICET. Universidad Nacional de General Sarmiento, J. M. Gutiérrez 1150, 1613, Los Polvorines, Buenos Aires, Argentina
| | - Ramon Eritja
- Institute for Advanced Chemistry of Catalonia (IQAC), Spanish Council for Scientific Research (CSIC), Jordi Girona 18-26, 08034, Barcelona, Spain.,Networking Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN)
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45
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Dembska A. The analytical and biomedical potential of cytosine-rich oligonucleotides: A review. Anal Chim Acta 2016; 930:1-12. [PMID: 27265899 DOI: 10.1016/j.aca.2016.05.007] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Revised: 04/30/2016] [Accepted: 05/04/2016] [Indexed: 02/04/2023]
Abstract
Polycytosine DNA strands are often found among natural sequences, including the ends of telomeres, centromeres, and introns or in the regulatory regions of genes. A characteristic feature of oligonucleotides that are rich in cytosine (C-rich) is their ability to associate under acidic conditions to form a tetraplex i-motif consisting of two parallel stranded cytosine-hemiprotonated cytosine (C·C+) base-paired duplexes that are mutually intercalated in an antiparallel orientation. Nanotechnology has been exploiting the advantages of i-motif pH-dependent formation to fabricate nanomachines, nanoswitches, electrodes and intelligent nanosurfaces or nanomaterials. Although a few reviews regarding the structure, properties and applications of i-motifs have been published, this review focuses on recently developed biosensors (e.g., to detect pH, glucose or silver ions) and drug-delivery biomaterials. Furthermore, we have included examples of sensors based on parallel C-rich triplexes and silver nanoclusters (AgNCs) fabricated on cytosine-rich DNA strands. The potential diagnostic and therapeutic applications of this type of material are discussed.
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Affiliation(s)
- Anna Dembska
- Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89b, 61-614 Poznan, Poland.
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46
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Wu Q, Wong JR, Qing Yeo PL, Zhang D, Shao F. Methylation on CpG repeats modulates hydroxymethylcytosine induced duplex destabilization. RSC Adv 2016. [DOI: 10.1039/c6ra08647k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The destabilization effect of 5-hydroxymethylcytosine on CpG repeats can be reversed in heavily methylated duplex.
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Affiliation(s)
- Qiong Wu
- Division of Chemistry and Biological Chemistry
- Nanyang Technological University
- Singapore 637371
- Singapore
| | - Jiun Ru Wong
- Division of Chemistry and Biological Chemistry
- Nanyang Technological University
- Singapore 637371
- Singapore
| | - Penny Liu Qing Yeo
- Division of Chemistry and Biological Chemistry
- Nanyang Technological University
- Singapore 637371
- Singapore
| | - Dawei Zhang
- Division of Chemistry and Biological Chemistry
- Nanyang Technological University
- Singapore 637371
- Singapore
| | - Fangwei Shao
- Division of Chemistry and Biological Chemistry
- Nanyang Technological University
- Singapore 637371
- Singapore
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47
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Lannes L, Halder S, Krishnan Y, Schwalbe H. Tuning the pH Response of i-Motif DNA Oligonucleotides. Chembiochem 2015; 16:1647-56. [PMID: 26032298 DOI: 10.1002/cbic.201500182] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Indexed: 12/19/2022]
Abstract
Cytosine-rich single-stranded DNA oligonucleotides are able to adopt an i-motif conformation, a four-stranded structure, near a pH of 6. This unique pH-dependent conformational switch is reversible and hence can be controlled by changing the pH. Here, we show that the pH response range of the human telomeric i-motif can be shifted towards more basic pH values by introducing 5-methylcytidines (5-MeC) and towards more acidic pH values by introducing 5-bromocytidines (5-BrC). No thermal destabilisation was observed in these chemically modified i-motif sequences. The time required to attain the new conformation in response to sudden pH changes was slow for all investigated sequences but was found to be ten times faster in the 5-BrC derivative of the i-motif.
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Affiliation(s)
- Laurie Lannes
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue-Strasse 7, 60438 Frankfurt/Main (Germany)
| | - Saheli Halder
- National Centre for Biological Sciences, TIFR, GKVK Campus, Bellary Road, Bangalore 560065 (India)
| | - Yamuna Krishnan
- National Centre for Biological Sciences, TIFR, GKVK Campus, Bellary Road, Bangalore 560065 (India).,Department of Chemistry, University of Chicago, E305, GCIS, 929 E, 57th Street, Chicago, IL 60637 (USA)
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue-Strasse 7, 60438 Frankfurt/Main (Germany).
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