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Boissieras J, Bonnet H, Susanto MF, Gomez D, Defrancq E, Granzhan A, Dejeu J. iMab antibody binds single-stranded cytosine-rich sequences and unfolds DNA i-motifs. Nucleic Acids Res 2024; 52:8052-8062. [PMID: 38908025 DOI: 10.1093/nar/gkae531] [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: 11/23/2023] [Revised: 05/31/2024] [Accepted: 06/10/2024] [Indexed: 06/24/2024] Open
Abstract
i-Motifs (iMs) are non-canonical, four-stranded secondary structures formed by stacking of hemi-protonated CH+·C base pairs in cytosine-rich DNA sequences, predominantly at pH < 7. The presence of iM structures in cells was a matter of debate until the recent development of iM-specific antibody, iMab, which was instrumental for several studies that suggested the existence of iMs in live cells and their putative biological roles. We assessed the interaction of iMab with cytosine-rich oligonucleotides by biolayer interferometry (BLI), pull-down assay and bulk-FRET experiments. Our results suggest that binding of iMab to DNA oligonucleotides is governed by the presence of runs of at least two consecutive cytosines and is generally increased in acidic conditions, irrespectively of the capacity of the sequence to adopt, or not, an iM structure. Moreover, the results of the bulk-FRET assay indicate that interaction with iMab results in unfolding of iM structures even in acidic conditions, similarly to what has been observed with hnRNP K, well-studied single-stranded DNA binding protein. Taken together, our results strongly suggest that iMab actually binds to blocks of 2-3 cytosines in single-stranded DNA, and call for more careful interpretation of results obtained with this antibody.
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Affiliation(s)
- Joseph Boissieras
- Chemistry and Modelling for Biology of Cancer (CMBC), CNRS UMR9187, INSERM U1196, Institut Curie, Université Paris Saclay, 91405 Orsay, France
| | - Hugues Bonnet
- Département de Chimie Moléculaire (DCM), CNRS UMR5250, Université Grenoble-Alpes, 38000 Grenoble, France
| | - Maria Fidelia Susanto
- Institut de Pharmacologie et Biologie Structurale (IPBS), CNRS UMR5089, Université Toulouse III - Paul Sabatier (UT3), Toulouse, France
| | - Dennis Gomez
- Institut de Pharmacologie et Biologie Structurale (IPBS), CNRS UMR5089, Université Toulouse III - Paul Sabatier (UT3), Toulouse, France
| | - Eric Defrancq
- Département de Chimie Moléculaire (DCM), CNRS UMR5250, Université Grenoble-Alpes, 38000 Grenoble, France
| | - Anton Granzhan
- Chemistry and Modelling for Biology of Cancer (CMBC), CNRS UMR9187, INSERM U1196, Institut Curie, Université Paris Saclay, 91405 Orsay, France
| | - Jérôme Dejeu
- Département de Chimie Moléculaire (DCM), CNRS UMR5250, Université Grenoble-Alpes, 38000 Grenoble, France
- SUPMICROTECH, Université Franche-Comté, Institut FEMTO-ST, 25000 Besançon, France
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2
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Wang J, Wang S, Zhang J, Ji D, Huang ZS, Li D. Regulation of VEGF gene expression by bisacridine derivative through promoter i-motif for cancer treatment. Biochim Biophys Acta Gen Subj 2024; 1868:130631. [PMID: 38685534 DOI: 10.1016/j.bbagen.2024.130631] [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: 01/16/2024] [Revised: 04/12/2024] [Accepted: 04/19/2024] [Indexed: 05/02/2024]
Abstract
BACKGROUND Vascular endothelial growth factor (VEGF) is overexpressed in most malignant tumors, which has important impact on tumor angiogenesis and development. Its gene promoter i-motif structure formed by C-rich sequence can regulate gene expression, which is a promising new target for anti-tumor therapy. METHODS We screened various compounds and studied their effects on VEGF through extensive experiments, including SPR, MST, TO displacement, FRET, CD, ESI-MS, NMR, MTT, clone formation, qPCR, Western blot, dual-luciferase reporter assay, immunofluorescence, cell scrape, apoptosis, transwell assay, and animal model. RESULTS After extensive screening, bisacridine derivative B09 was found to have selective binding and stabilization to VEGF promoter i-motif, which could down-regulate VEGF gene expression. B09 showed potent inhibition on MCF-7 and HGC-27 cell proliferation and metastasis. B09 significantly inhibited tumor growth in xenograft mice model with HGC-27 cells, showing decreased VEGF expression analyzed through immunohistochemistry. CONCLUSION B09 could specifically regulate VEGF gene expression, possibly through interacting with promoter i-motif structure. As a lead compound, B09 could be further developed for innovative anti-cancer agent targeting VEGF.
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Affiliation(s)
- Jing Wang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, Guangzhou, PR China
| | - Siyi Wang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, Guangzhou, PR China
| | - Jiahui Zhang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, Guangzhou, PR China
| | - Dongsheng Ji
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, Guangzhou, PR China
| | - Zhi-Shu Huang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, Guangzhou, PR China
| | - Ding Li
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, Guangzhou, PR China.
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3
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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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4
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Mir B, Serrano-Chacón I, Medina P, Macaluso V, Terrazas M, Gandioso A, Garavís M, Orozco M, Escaja N, González C. Site-specific incorporation of a fluorescent nucleobase analog enhances i-motif stability and allows monitoring of i-motif folding inside cells. Nucleic Acids Res 2024; 52:3375-3389. [PMID: 38366792 PMCID: PMC11014255 DOI: 10.1093/nar/gkae106] [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: 04/28/2023] [Revised: 01/17/2024] [Accepted: 02/09/2024] [Indexed: 02/18/2024] Open
Abstract
The i-motif is an intriguing non-canonical DNA structure, whose role in the cell is still controversial. Development of methods to study i-motif formation under physiological conditions in living cells is necessary to study its potential biological functions. The cytosine analog 1,3-diaza-2-oxophenoxazine (tCO) is a fluorescent nucleobase able to form either hemiprotonated base pairs with cytosine residues, or neutral base pairs with guanines. We show here that when tCO is incorporated in the proximity of a G:C:G:C minor groove tetrad, it induces a strong thermal and pH stabilization, resulting in i-motifs with Tm of 39ºC at neutral pH. The structural determination by NMR methods reveals that the enhanced stability is due to a large stacking interaction between the guanines of the tetrad with the tCO nucleobase, which forms a tCO:C+ in the folded structure at unusually-high pHs, leading to an increased quenching in its fluorescence at neutral conditions. This quenching is much lower when tCO is base-paired to guanines and totally disappears when the oligonucleotide is unfolded. By taking profit of this property, we have been able to monitor i-motif folding in cells.
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Affiliation(s)
- Bartomeu Mir
- Instituto de Química Física ‘Blas Cabrera’. CSIC. Serrano 119. 28006 Madrid. Spain
- Inorganic and Organic Chemistry Department. Organic Chemistry Section and IBUB. University of Barcelona, Martí i Franquès 1-11, 08028 Barcelona. Spain
| | - Israel Serrano-Chacón
- Instituto de Química Física ‘Blas Cabrera’. CSIC. Serrano 119. 28006 Madrid. Spain
- Institute for Research in Biomedicine (IRB Barcelona). The Barcelona Institute of Science and Technology (BIST). 08028 Barcelona. Spain
| | - Pedro Medina
- Institute for Research in Biomedicine (IRB Barcelona). The Barcelona Institute of Science and Technology (BIST). 08028 Barcelona. Spain
- Departament de Bioquímica i Biomedicina. Facultat de Biologia. Universitat de Barcelona. 08028 Barcelona. Spain
| | - Veronica Macaluso
- Institute for Research in Biomedicine (IRB Barcelona). The Barcelona Institute of Science and Technology (BIST). 08028 Barcelona. Spain
| | - Montserrat Terrazas
- Institute for Research in Biomedicine (IRB Barcelona). The Barcelona Institute of Science and Technology (BIST). 08028 Barcelona. Spain
- Inorganic and Organic Chemistry Department. Organic Chemistry Section and IBUB. University of Barcelona, Martí i Franquès 1-11, 08028 Barcelona. Spain
| | - Albert Gandioso
- Institute for Research in Biomedicine (IRB Barcelona). The Barcelona Institute of Science and Technology (BIST). 08028 Barcelona. Spain
| | - Miguel Garavís
- Instituto de Química Física ‘Blas Cabrera’. CSIC. Serrano 119. 28006 Madrid. Spain
| | - Modesto Orozco
- Institute for Research in Biomedicine (IRB Barcelona). The Barcelona Institute of Science and Technology (BIST). 08028 Barcelona. Spain
- Departament de Bioquímica i Biomedicina. Facultat de Biologia. Universitat de Barcelona. 08028 Barcelona. Spain
| | - Núria Escaja
- Inorganic and Organic Chemistry Department. Organic Chemistry Section and IBUB. University of Barcelona, Martí i Franquès 1-11, 08028 Barcelona. Spain
| | - Carlos González
- Instituto de Química Física ‘Blas Cabrera’. CSIC. Serrano 119. 28006 Madrid. Spain
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5
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Lala B, Chaudhuri R, Prasanth T, Burkhart I, Schwalbe H, Dash J. Guanosine-based hydrogel as a supramolecular scaffold for template-assisted macrocyclization. Chem Commun (Camb) 2024; 60:3433-3436. [PMID: 38444274 DOI: 10.1039/d4cc00129j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2024]
Abstract
The G-quartet-like supramolecular assembly present in guanosine hydrogel templates macrocyclization between bis-azide and bis-alkyne fragments. The resulting macrocycle enhances viscoelastic properties, and strengthens the hydrogel network. This approach holds potential for the in situ synthesis of drugs and their simultaneous delivery in a stimuli-responsive manner.
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Affiliation(s)
- Binayak Lala
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700032, India.
| | - Ritapa Chaudhuri
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700032, India.
| | - Thumpati Prasanth
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700032, India.
| | - Ines Burkhart
- Institute of Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University, Max-von-Laue Strasse 7, Frankfurt, D-60438, Germany
| | - Harald Schwalbe
- Institute of Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University, Max-von-Laue Strasse 7, Frankfurt, D-60438, Germany
| | - Jyotirmayee Dash
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700032, India.
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6
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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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7
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Martinez-Fernandez L, Improta R. The photophysics of protonated cytidine and hemiprotonated cytidine base pair: A computational study. Photochem Photobiol 2024; 100:314-322. [PMID: 37409732 DOI: 10.1111/php.13832] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 05/25/2023] [Accepted: 06/19/2023] [Indexed: 07/07/2023]
Abstract
We here study the effect that a lowering of the pH has on the excited state processes of cytidine and a cytidine/cytidine pair in solution, by integrating time-dependent density functional theory and CASSCF/CASPT2 calculations, and including solvent by a mixed discrete/continuum model. Our calculations reproduce the effect of protonation at N3 on the steady-state infrared and absorption spectra of a protonated cytidine (CH+ ), and predict that an easily accessible non-radiative deactivation route exists for the spectroscopic state, explaining its sub-ps lifetime. Indeed, an extremely small energy barrier separates the minimum of the lowest energy bright state from a crossing region with the ground electronic state, reached by out-of-plane motion of the hydrogen substituents of the CC double bond, the so-called ethylenic conical intersection typical of cytidine and other pyrimidine bases. This deactivation route is operative for the two bases forming an hemiprotonated cytidine base pair, [CH·C]+ , the building blocks of I-motif secondary structures, whereas interbase processes play a minor role. N3 protonation disfavors instead the nπ* transitions, associated with the long-living components of cytidine photoactivated dynamics.
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Affiliation(s)
- Lara Martinez-Fernandez
- Departamento de Química, Facultad de Ciencias and Institute for Advanced Research in Chemical Sciences (IADCHEM), Universidad Autónoma de Madrid, Campus de Excelencia UAM-CSIC, Madrid, Spain
| | - Roberto Improta
- Consiglio Nazionale delle Ricerche, Istituto di Biostrutture e Bioimmagini (IBB-CNR), Naples, Italy
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8
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Luo Y, Živković ML, Wang J, Ryneš J, Foldynová-Trantírková S, Trantírek L, Verga D, Mergny JL. A sodium/potassium switch for G4-prone G/C-rich sequences. Nucleic Acids Res 2024; 52:448-461. [PMID: 37986223 PMCID: PMC10783510 DOI: 10.1093/nar/gkad1073] [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: 06/10/2023] [Revised: 10/19/2023] [Accepted: 11/03/2023] [Indexed: 11/22/2023] Open
Abstract
Metal ions are essential components for the survival of living organisms. For most species, intracellular and extracellular ionic conditions differ significantly. As G-quadruplexes (G4s) are ion-dependent structures, changes in the [Na+]/[K+] ratio may affect the folding of genomic G4s. More than 11000 putative G4 sequences in the human genome (hg19) contain at least two runs of three continuous cytosines, and these mixed G/C-rich sequences may form a quadruplex or a competing hairpin structure based on G-C base pairing. In this study, we examine how the [Na+]/[K+] ratio influences the structures of G/C-rich sequences. The natural G4 structure with a 9-nt long central loop, CEBwt, was chosen as a model sequence, and the loop bases were gradually replaced by cytosines. The series of CEB mutations revealed that the presence of cytosines in G4 loops does not prevent G4 folding or decrease G4 stability but increases the probability of forming a competing structure, either a hairpin or an intermolecular duplex. Slow conversion to the quadruplex in vitro (in a potassium-rich buffer) and cells was demonstrated by NMR. 'Shape-shifting' sequences may respond to [Na+]/[K+] changes with delayed kinetics.
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Affiliation(s)
- Yu Luo
- Laboratoire d’Optique et Biosciences, Ecole Polytechnique, CNRS, Inserm, Institut Polytechnique de Paris, 91128 Palaiseau, France
- CNRS UMR9187, INSERM U1196, Université Paris-Saclay, F-91405 Orsay, France
| | - 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
| | - Jiawei Wang
- Laboratoire d’Optique et Biosciences, Ecole Polytechnique, CNRS, Inserm, Institut Polytechnique de Paris, 91128 Palaiseau, France
| | - Jan Ryneš
- Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic
| | | | - Lukáš Trantírek
- Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic
| | - Daniela Verga
- CNRS UMR9187, INSERM U1196, Université Paris-Saclay, F-91405 Orsay, France
- CNRS UMR9187, INSERM U1196, Institut Curie, PSL Research University, F-91405 Orsay, France
| | - Jean-Louis Mergny
- Laboratoire d’Optique et Biosciences, Ecole Polytechnique, CNRS, Inserm, Institut Polytechnique de Paris, 91128 Palaiseau, France
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9
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Boissieras J, Granzhan A. Potentiometric titrations to study ligand interactions with DNA i-motifs. Methods Enzymol 2023; 695:233-254. [PMID: 38521587 DOI: 10.1016/bs.mie.2023.11.005] [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] [Indexed: 03/25/2024]
Abstract
i-Motifs are non-canonical secondary structures of DNA formed by mutual intercalation of hemi-protonated cytosine-cytosine base pairs, most typically in slightly acidic conditions (pH<7.0). These structures are well-studied in vitro and have recently been suggested to exist in cells. Despite nearly a decade of active research, the quest for small-molecule ligands that could selectively bind to and stabilize i-motifs continues, and no reference, bona fide i-motif ligand is currently available. This is, at least in part, due to the lack of robust methods to assess the interaction of ligands with i-motifs, since many techniques well-established for studies of other secondary structures (such as CD-, UV-, and FRET-melting) may generate artifacts when applied to i-motifs. Here, we describe an implementation of automated, potentiometric (pH) titrations as a robust isothermal method to assess the impact of ligands or cosolutes on thermodynamic stability of i-motifs. This approach is validated through the use of a cosolute previously known to stabilize i-motifs (PEG2000) and three small-molecule ligands that are able to stabilize, destabilize, or have no effect on the stability of i-motifs, respectively.
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Affiliation(s)
- Joseph Boissieras
- CMBC, CNRS UMR9187, INSERM U1196, Institut Curie, PSL Research University, Orsay, France; CMBC, CNRS UMR9187, INSERM U1196, Université Paris Saclay, Orsay, France
| | - Anton Granzhan
- CMBC, CNRS UMR9187, INSERM U1196, Institut Curie, PSL Research University, Orsay, France; CMBC, CNRS UMR9187, INSERM U1196, Université Paris Saclay, Orsay, France.
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10
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Sengupta P, Jamroskovic J, Sabouri N. A beginner's handbook to identify and characterize i-motif DNA. Methods Enzymol 2023; 695:45-70. [PMID: 38521590 DOI: 10.1016/bs.mie.2023.11.001] [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] [Indexed: 03/25/2024]
Abstract
Genomic DNA exhibits an innate ability to manifest diverse sequence-dependent secondary structures, serving crucial functions in gene regulation and cellular equilibrium. While extensive research has confirmed the formation of G-quadruplex structures by guanine-rich sequences in vitro and in cells, recent investigations have turned the quadruplex community's attention to the cytosine (C)-rich complementary strands that can adopt unique tetra-stranded conformation, termed as intercalated motif or i-motif. I-motifs are stabilized by hemi-protonated C:CH+ base pairs under acidic conditions. Initially, the in vivo occurrence of i-motifs was underestimated because their formation is favored at non-physiological pH. However, groundbreaking research utilizing the structure-specific iMab antibody and high-throughput sequencing have recently detected their conserved dispersion throughout the genome, challenging previous assumptions. Given the evolving nature of this research field, it becomes imperative to conduct independent in vitro experiments aimed at identifying potential i-motif formation in C-rich sequences and consolidating the findings to address the properties of i-motifs. This chapter serves as an introductory guide for the swift identification of novel i-motifs, where we present an experimental framework for investigating and characterizing i-motif sequences in vitro. In this chapter, we selected a synthetic oligonucleotide (C7T3) sequence and outlined appropriate methodologies for annealing the i-motif structure into suitable buffers. Then, we validated its formation by CD (Circular Dichroism) and NMR (Nuclear Magnetic Resonance) spectroscopy. Finally, we provided a thorough account of the step-by-step procedures to investigate the effect of i-motif formation on the stalling or retardation of DNA replication using high resolution primer extension assays.
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Affiliation(s)
- Pallabi Sengupta
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Jan Jamroskovic
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Nasim Sabouri
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden.
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11
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Dzurov M, Pospíšilová Š, Krafčíková M, Trantírek L, Vojtová L, Ryneš J. A thermosensitive gel matrix for bioreactor-assisted in-cell NMR of nucleic acids and proteins. JOURNAL OF BIOMOLECULAR NMR 2023; 77:203-215. [PMID: 37688760 PMCID: PMC10687187 DOI: 10.1007/s10858-023-00422-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 07/15/2023] [Indexed: 09/11/2023]
Abstract
Introducing the flow through the bioreactor has revolutionized in-cell NMR spectroscopy by prolonging the measurement time available to acquire spectral information about biomacromolecules in metabolically active cells. Bioreactor technology relies on immobilizer matrices, which secure cells in the active volume of the NMR coil and enable uniform perfusion of the growth medium, supplying fresh nutrients to the cells while removing toxic byproducts of their metabolism. The main drawbacks of commonly used matrices include the inability to recover intact cells post-measurement for additional analyses and/or requirements for specific operating temperatures. Here, we report on the development and characterization of a set of thermosensitive and nontoxic triblock copolymers based on poly(D,L-lactide)-b-poly(ethylene glycol)-b-poly(D,L-lactide) (PLA-PEG-PLA). Here, we show for the first time that these copolymers are suitable as immobilizer matrices for the acquisition of in-cell NMR spectra of nucleic acids and proteins over a commonly used sample temperature range of 15-40 °C and, importantly, allow recovery of cells after completion of in-cell NMR spectra acquisition. We compared the performances of currently used matrices in terms of cell viability (dye exclusion assays), cellular metabolism (1D 31P NMR), and quality of in-cell NMR spectra of two model biomacromolecules (hybrid double-stranded/i-motif DNA and ubiquitin). Our results demonstrate the suitability and advantages of PLA-PEG-PLA copolymers for application in bioreactor-assisted in-cell NMR.
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Affiliation(s)
- Matej Dzurov
- CEITEC - Central European Institute of Technology, Brno University of Technology, Purkyňova 656/123, Brno, 612 00, Czech Republic
| | - Šárka Pospíšilová
- CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 753/5, Brno, 625 00, Czech Republic
| | - Michaela Krafčíková
- National Centre for Biomolecular Research, Masaryk University, Kamenice 753/5, Brno, 625 00, Czech Republic
- Institute of Biophysics, Czech Academy of Sciences, Královopolská 135, Brno, 612 65, Czech Republic
- Bijvoet Centre for Biomolecular Research, Utrecht University, Padualaan 12, Utrecht, 3584 CH, The Netherlands
| | - Lukáš Trantírek
- CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 753/5, Brno, 625 00, Czech Republic
| | - Lucy Vojtová
- CEITEC - Central European Institute of Technology, Brno University of Technology, Purkyňova 656/123, Brno, 612 00, Czech Republic.
| | - Jan Ryneš
- CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 753/5, Brno, 625 00, Czech Republic.
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12
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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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13
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Luo Y, Granzhan A, Marquevielle J, Cucchiarini A, Lacroix L, Amrane S, Verga D, Mergny JL. Guidelines for G-quadruplexes: I. In vitro characterization. Biochimie 2023; 214:5-23. [PMID: 36596406 DOI: 10.1016/j.biochi.2022.12.019] [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: 10/29/2022] [Revised: 12/19/2022] [Accepted: 12/28/2022] [Indexed: 01/02/2023]
Abstract
Besides the well-known DNA double-helix, non-canonical nucleic acid structures regulate crucial biological activities. Among these oddities, guanine-rich DNA sequences can form unusual four-stranded secondary structures called G-quadruplexes (G4s). G4-prone sequences have been found in the genomes of most species, and G4s play important roles in essential processes such as transcription, replication, genome integrity and epigenetic regulation. Here, we present a short overview of G-quadruplexes followed by a detailed description of the biophysical and biochemical methods used to characterize G4s in vitro. The principles, experimental details and possible shortcomings of each method are discussed to provide a comprehensive view of the techniques used to study these structures. We aim to provide a set of guidelines for standardizing research on G-quadruplexes; these guidelines are not meant to be a dogmatic set of rules, but should rather provide useful information on the methods currently used to study these fascinating motifs.
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Affiliation(s)
- Yu Luo
- Laboratoire D'Optique et Biosciences, Ecole Polytechnique, CNRS, Inserm, Institut Polytechnique de Paris, 91120, Palaiseau, France; CNRS UMR9187, INSERM U1196, Université Paris-Saclay, F-91405, Orsay, France
| | - Anton Granzhan
- CNRS UMR9187, INSERM U1196, Université Paris-Saclay, F-91405, Orsay, France; CNRS UMR9187, INSERM U1196, Institut Curie, PSL Research University, F-91405, Orsay, France
| | - Julien Marquevielle
- Université de Bordeaux, ARNA Laboratory, INSERM U1212, CNRS UMR 5320, IECB, 33076, Bordeaux, France
| | - Anne Cucchiarini
- Laboratoire D'Optique et Biosciences, Ecole Polytechnique, CNRS, Inserm, Institut Polytechnique de Paris, 91120, Palaiseau, France
| | - Laurent Lacroix
- Institut de Biologie de L'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, CNRS, INSERM, Université PSL, Paris, France
| | - Samir Amrane
- Université de Bordeaux, ARNA Laboratory, INSERM U1212, CNRS UMR 5320, IECB, 33076, Bordeaux, France
| | - Daniela Verga
- CNRS UMR9187, INSERM U1196, Université Paris-Saclay, F-91405, Orsay, France; CNRS UMR9187, INSERM U1196, Institut Curie, PSL Research University, F-91405, Orsay, France.
| | - Jean-Louis Mergny
- Laboratoire D'Optique et Biosciences, Ecole Polytechnique, CNRS, Inserm, Institut Polytechnique de Paris, 91120, Palaiseau, France; Institute of Biophysics of the Czech Academy of Sciences, Brno, Czech Republic.
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14
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El-Khoury R, Roman M, Assi HA, Moye AL, Bryan T, Damha M. Telomeric i-motifs and C-strands inhibit parallel G-quadruplex extension by telomerase. Nucleic Acids Res 2023; 51:10395-10410. [PMID: 37742080 PMCID: PMC10602923 DOI: 10.1093/nar/gkad764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 08/23/2023] [Accepted: 09/11/2023] [Indexed: 09/25/2023] Open
Abstract
Telomeric C-rich repeated DNA sequences fold into tetrahelical i-motif structures in vitro at acidic pH. While studies have suggested that i-motifs may form in cells, little is known about their potential role in human telomere biology. In this study, we explore the effect of telomeric C-strands and i-motifs on the ability of human telomerase to extend G-rich substrates. To promote i-motif formation at neutral pH, we use telomeric sequences where the cytidines have been substituted with 2'-fluoroarabinocytidine. Using FRET-based studies, we show that the stabilized i-motifs resist hybridization to concomitant parallel G-quadruplexes, implying that both structures could exist simultaneously at telomeric termini. Moreover, through telomerase activity assays, we show that both unstructured telomeric C-strands and telomeric i-motifs can inhibit the activity and processivity of telomerase extension of parallel G-quadruplexes and linear telomeric DNA. The data suggest at least three modes of inhibition by C-strands and i-motifs: direct hybridization to the substrate DNA, hybridization to nascent product DNA resulting in early telomerase dissociation, and interference with the unique mechanism of telomerase unwinding and extension of a G-quadruplex. Overall, this study highlights a potential inhibitory role for the telomeric C-strand in telomere maintenance.
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Affiliation(s)
- Roberto El-Khoury
- Department of Chemistry, McGill University, Montreal, Quebec H3A 0B8, Canada
| | - Morgane Roman
- Department of Chemistry, McGill University, Montreal, Quebec H3A 0B8, Canada
| | - Hala Abou Assi
- Department of Chemistry, McGill University, Montreal, Quebec H3A 0B8, Canada
| | - Aaron L Moye
- Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW 2145, Australia
| | - Tracy M Bryan
- Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW 2145, Australia
| | - Masad J Damha
- Department of Chemistry, McGill University, Montreal, Quebec H3A 0B8, Canada
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15
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Bchara L, Eritja R, Gargallo R, Benavente F. Rapid and Highly Efficient Separation of i-Motif DNA Species by CE-UV and Multivariate Curve Resolution. Anal Chem 2023; 95:15189-15198. [PMID: 37782260 PMCID: PMC10585953 DOI: 10.1021/acs.analchem.3c01730] [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: 04/21/2023] [Accepted: 09/12/2023] [Indexed: 10/03/2023]
Abstract
The i-motif is a class of nonstandard DNA structure with potential biological implications. A novel capillary electrophoresis with an ultraviolet absorption spectrophotometric detection (CE-UV) method has been developed for the rapid analysis of the i-motif folding equilibrium as a function of pH and temperature. The electrophoretic analyses are performed in reverse polarity of the separation voltage with 32 cm long fused silica capillaries permanently coated with hydroxypropyl cellulose (HPC), after an appropriate conditioning procedure was used to achieve good repeatability. However, the electrophoretic separation between the folded and unfolded conformers of the studied cytosine-rich i-motif sequences (i.e., TT, Py39WT, and nmy01) is compromised, especially for Py39WT and nmy01, which result in completely overlapped peaks. Therefore, deconvolution with multivariate curve resolution-alternating least-squares (MCR-ALS) has been required for the efficient separation of the folded and unfolded species found at different concentration levels at pH 6.5 and between 12 and 40 °C, taking advantage of the small dissimilarities in the electrophoretic mobilities and UV spectra levels. MCR-ALS has also provided quantitative information that has been used to estimate melting temperatures (Tm), which are similar to those determined by UV and circular dichroism (CD) spectroscopies. The obtained results demonstrate that CE-UV assisted by MCR-ALS may become a very useful tool to get novel insight into the folding of i-motifs and other complex DNA structures.
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Affiliation(s)
- Laila Bchara
- Department
of Chemical Engineering and Analytical Chemistry, University of Barcelona, Marti i Franquès 1-11, E-08028 Barcelona, Spain
| | - Ramon Eritja
- Institute
for Advanced Chemistry of Catalonia (IQAC−CSIC), CIBER-BBN, Jordi Girona 18-26, E-08034 Barcelona, Spain
| | - Raimundo Gargallo
- Department
of Chemical Engineering and Analytical Chemistry, University of Barcelona, Marti i Franquès 1-11, E-08028 Barcelona, Spain
| | - Fernando Benavente
- Department
of Chemical Engineering and Analytical Chemistry, University of Barcelona, Marti i Franquès 1-11, E-08028 Barcelona, Spain
- Institute
for Research on Nutrition and Food Safety (INSA·UB), University of Barcelona, Av. Prat de la Riba 171, E-08921 Santa Coloma de Gramenet, Spain
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16
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Ghezzo M, Trajkovski M, Plavec J, Sissi C. A Screening Protocol for Exploring Loop Length Requirements for the Formation of a Three Cytosine-Cytosine + Base-Paired i-Motif. Angew Chem Int Ed Engl 2023; 62:e202309327. [PMID: 37611164 DOI: 10.1002/anie.202309327] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 08/21/2023] [Accepted: 08/23/2023] [Indexed: 08/25/2023]
Abstract
DNA sequences containing at least four runs of repetitive cytosines can fold into tetra-helical structures called i-Motifs (iMs). The interest in these DNA secondary structures is increasing due to their therapeutical and technological applications. Still, limited knowledge of their folding requirements is currently available. We developed a novel step-by-step pipeline for the systematic screening of putative iM-forming model sequences. Focusing on structures comprising only three cytosine-cytosine+ base pairs, we investigated what the minimal lengths of the loops required for formation of an intra-molecular iM are. Our data indicate that two and three nucleotides are required to connect the strands through the minor and majorgrooves of the iM, respectively. Additionally, they highlight an asymmetric behavior according to the distribution of the cytosines. Specifically, no sequence containing a single cytosine in the first and third run was able to fold into intra-molecular iMs with the same stability of those formed when the first and the third run comprise two cytosines. This knowledge represents a step forward toward the development of prediction tools for the proper identification of biologically functional iMs, as well as for the rational design of these secondary structures as technological devices.
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Affiliation(s)
- Michele Ghezzo
- Department of Pharmaceutical and Pharmacological Science, University of Padua, Via Marzolo 5, 35131, Padua, Italy
| | - Marko Trajkovski
- Slovenian NMR Centre, National Institute of Chemistry, Hajdrihova 19, 1000, Ljubljana, Slovenia
| | - Janez Plavec
- Slovenian NMR Centre, National Institute of Chemistry, Hajdrihova 19, 1000, Ljubljana, Slovenia
| | - Claudia Sissi
- Department of Pharmaceutical and Pharmacological Science, University of Padua, Via Marzolo 5, 35131, Padua, Italy
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17
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Das S, Takahashi S, Ohyama T, Bhowmik S, Sugimoto N. Theranostic approach to specifically targeting the interloop region of BCL2 i-motif DNA by crystal violet. Sci Rep 2023; 13:14338. [PMID: 37658102 PMCID: PMC10474294 DOI: 10.1038/s41598-023-39407-9] [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: 05/17/2023] [Accepted: 07/25/2023] [Indexed: 09/03/2023] Open
Abstract
Ligands that recognise specific i-motif DNAs are helpful in cancer diagnostics and therapeutics, as i-motif formation can cause cancer. Although the loop regions of i-motifs are promising targets for ligands, the interaction between a ligand and the loop regions based on sequence information remains unexplored. Herein, we investigated the loop regions of various i-motif DNAs to determine whether these regions specifically interact with fluorescent ligands. Crystal violet (CV), a triphenylmethane dye, exhibited strong fluorescence with the i-motif derived from the promoter region of the human BCL2 gene in a sequence- and structure-specific manner. Our systematic sequence analysis indicated that CV was bound to the site formed by the first and third loops through inter-loop interactions between the guanine bases present in these loops. As the structural stability of the BCL2 i-motif was unaffected by CV, the local stabilisation of the loops by CV could inhibit the interaction of transcription factors with these loops, repressing the BCL2 expression of MCF-7 cells. Our finding suggests that the loops of the i-motif can act as a novel platform for the specific binding of small molecules; thus, they could be utilised for the theranostics of diseases associated with i-motif DNAs.
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Affiliation(s)
- Sinjan Das
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, 7-1-20 Minatojima-Minamimachi, Kobe, 650-0047, Japan
| | - Shuntaro Takahashi
- 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
| | - Sudipta Bhowmik
- Department of Biophysics, Molecular Biology and Bioinformatics, University of Calcutta, 92, A.P.C Road, Kolkata, 700009, India
- Mahatma Gandhi Medical Advanced Research Institute (MGMARI), Sri Balaji Vidyapeeth (Deemed to be University), Pondy-Cuddalore Main Road, Pillayarkuppam, Pondicherry, 607402, India
| | - 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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Pandey A, Roy S, Srivatsan SG. Probing the Competition between Duplex, G-Quadruplex and i-Motif Structures of the Oncogenic c-Myc DNA Promoter Region. Chem Asian J 2023; 18:e202300510. [PMID: 37541298 DOI: 10.1002/asia.202300510] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 07/09/2023] [Indexed: 08/06/2023]
Abstract
Development of probe systems that provide unique spectral signatures for duplex, G-quadruplex (GQ) and i-motif (iM) structures is very important to understand the relative propensity of a G-rich-C-rich promoter region to form these structures. Here, we devise a platform using a combination of two environment-sensitive nucleoside analogs namely, 5-fluorobenzofuran-modified 2'-deoxyuridine (FBF-dU) and 5-fluoro-2'-deoxyuridine (F-dU) to study the structures adopted by a promoter region of the c-Myc oncogene. FBF-dU serves as a dual-purpose probe containing a fluorescent and 19 F NMR label. When incorporated into the C-rich sequence, it reports the formation of different iMs via changes in its fluorescence properties and 19 F signal. F-dU incorporated into the G-rich ON reports the formation of a GQ structure whose 19 F signal is clearly different from the signals obtained for iMs. Rewardingly, the labeled ONs when mixed with respective complementary strands allows us to determine the relative population of different structures formed by the c-Myc promoter by the virtue of the probe's ability to produce distinct and resolved 19 F signatures for different structures. Our results indicate that at physiological pH and temperature the c-Myc promoter forms duplex, random coil and GQ structures, and does not form an iM. Whereas at acidic pH, the mixture largely forms iM and GQ structures. Taken together, our system will complement existing tools and provide unprecedented insights on the population equilibrium and dynamics of nucleic acid structures under different conditions.
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Affiliation(s)
- Akanksha Pandey
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune, Dr. Homi Bhabha Road, Pune, 411008, India
| | - Sarupa Roy
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune, Dr. Homi Bhabha Road, Pune, 411008, India
| | - Seergazhi G Srivatsan
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune, Dr. Homi Bhabha Road, Pune, 411008, India
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19
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Improta R. Shedding Light on the Photophysics and Photochemistry of I-Motifs Using Quantum Mechanical Calculations. Int J Mol Sci 2023; 24:12614. [PMID: 37628797 PMCID: PMC10454157 DOI: 10.3390/ijms241612614] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 08/07/2023] [Indexed: 08/27/2023] Open
Abstract
I-motifs are non-canonical DNA structures formed by intercalated hemiprotonated (CH·C)+ pairs, i.e., formed by a cytosine (C) and a protonated cytosine (CH+), which are currently drawing great attention due to their biological relevance and promising nanotechnological properties. It is important to characterize the processes occurring in I-motifs following irradiation by UV light because they can lead to harmful consequences for genetic code and because optical spectroscopies are the most-used tools to characterize I-motifs. By using time-dependent DFT calculations, we here provide the first comprehensive picture of the photoactivated behavior of the (CH·C)+ core of I-motifs, from absorption to emission, while also considering the possible photochemical reactions. We reproduce and assign their spectral signatures, i.e., infrared, absorption, fluorescence and circular dichroism spectra, disentangling the underlying chemical-physical effects. We show that the main photophysical paths involve C and CH+ bases on adjacent steps and, using this basis, interpret the available time-resolved spectra. We propose that a photodimerization reaction can occur on an excited state with strong C→CH+ charge transfer character and examine some of the possible photoproducts. Based on the results reported, some future perspectives for the study of I-motifs are discussed.
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Affiliation(s)
- Roberto Improta
- Consiglio Nazionale delle Ricerche, Istituto di Biostrutture e Bioimmagini (IBB-CNR), Via De Amicis 95, I-80145 Napoli, Italy
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20
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Eladl O, Yamaoki Y, Kondo K, Nagata T, Katahira M. Complex Formation of an RNA Aptamer with a Part of HIV-1 Tat through Induction of Base Triples in Living Human Cells Proven by In-Cell NMR. Int J Mol Sci 2023; 24:ijms24109069. [PMID: 37240414 DOI: 10.3390/ijms24109069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 05/19/2023] [Accepted: 05/19/2023] [Indexed: 05/28/2023] Open
Abstract
An RNA aptamer that strongly binds to a target molecule has the potential to be a nucleic acid drug inside living human cells. To investigate and improve this potential, it is critical to elucidate the structure and interaction of RNA aptamers inside living cells. We examined an RNA aptamer for HIV-1 Tat (TA), which had been found to trap Tat and repress its function in living human cells. We first used in vitro NMR to examine the interaction between TA and a part of Tat containing the binding site for trans-activation response element (TAR). It was revealed that two U-A∗U base triples are formed in TA upon binding of Tat. This was assumed to be critical for strong binding. Then, TA in complex with a part of Tat was incorporated into living human cells. The presence of two U-A∗U base triples was also revealed for the complex in living human cells by in-cell NMR. Thus, the activity of TA in living human cells was rationally elucidated by in-cell NMR.
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Grants
- 20H03192, 20K21477, 21H05519, and 22H05596 to M. K., 17H05878 and 20K06524 to T. N., and 19K16054 and 22K05314 to Y. Y.) Japan Society for the Promotion of Science
- (20fk0410027 and 23fk0410048 to M. K., and 22ak0101097 to T. N.) Japan Agency for Medical Research and Development
- NMRCR-22-05 to T. N. The Collaborative Research Program of the Institute for Protein Research, Osaka University
- to Y.Y The Collaboration Program of the Laboratory for Complex Energy Processes, Institute of Ad-vanced Energy, Kyoto University
- 235181 to O.E Ministry of Education, Culture, Sports, Science and Technology
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Affiliation(s)
- Omar Eladl
- Structural Energy Bioscience Research Section, Institute of Advanced Energy, Kyoto University, Kyoto 611-0011, Japan
- Graduate School of Energy Science, Kyoto University, Kyoto 606-8501, Japan
- Faculty of Pharmacy, Zagazig University, Zagazig 44519, Egypt
| | - Yudai Yamaoki
- Structural Energy Bioscience Research Section, Institute of Advanced Energy, Kyoto University, Kyoto 611-0011, Japan
- Graduate School of Energy Science, Kyoto University, Kyoto 606-8501, Japan
- Integrated Research Center for Carbon Negative Science, Institute of Advanced Energy, Kyoto University, Uji 611-0011, Japan
| | - Keiko Kondo
- Structural Energy Bioscience Research Section, Institute of Advanced Energy, Kyoto University, Kyoto 611-0011, Japan
- Integrated Research Center for Carbon Negative Science, Institute of Advanced Energy, Kyoto University, Uji 611-0011, Japan
- Biomass Product Tree Industry-Academia Collaborative Research Laboratory, Kyoto University, Kyoto 611-0011, Japan
| | - Takashi Nagata
- Structural Energy Bioscience Research Section, Institute of Advanced Energy, Kyoto University, Kyoto 611-0011, Japan
- Graduate School of Energy Science, Kyoto University, Kyoto 606-8501, Japan
- Integrated Research Center for Carbon Negative Science, Institute of Advanced Energy, Kyoto University, Uji 611-0011, Japan
| | - Masato Katahira
- Structural Energy Bioscience Research Section, Institute of Advanced Energy, Kyoto University, Kyoto 611-0011, Japan
- Graduate School of Energy Science, Kyoto University, Kyoto 606-8501, Japan
- Integrated Research Center for Carbon Negative Science, Institute of Advanced Energy, Kyoto University, Uji 611-0011, Japan
- Biomass Product Tree Industry-Academia Collaborative Research Laboratory, Kyoto University, Kyoto 611-0011, Japan
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21
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Rodriguez J, Domínguez A, Aviñó A, Borgonovo G, Eritja R, Mazzini S, Gargallo R. Exploring the stabilizing effect on the i-motif of neighboring structural motifs and drugs. Int J Biol Macromol 2023; 242:124794. [PMID: 37182626 DOI: 10.1016/j.ijbiomac.2023.124794] [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: 03/13/2023] [Revised: 04/18/2023] [Accepted: 04/25/2023] [Indexed: 05/16/2023]
Abstract
Cytosine-rich DNA sequences may fold into a structure known as i-motif, with potential in vivo modulation of gene expression. The stability of the i-motif is residual at neutral pH values. To increase it, the addition of neighboring moieties, such as Watson-Crick stabilized loops, tetrads, or non-canonical base pairs have been proposed. Taking a recently described i-motif structure as a model, the relative effect of these structural moieties, as well as several DNA ligands, on the stabilization of the i-motif has been studied. To this end, not only the original sequence but different mutants were considered. Spectroscopic techniques, PAGE, and multivariate data analysis methods have been used to model the folding/unfolding equilibria induced by changes of pH, temperature, and the presence of ligands. The results have shown that the duplex is the moiety that is responsible of the stabilization of the i-motif structure at neutral pH. The T:T base pair, on the contrary, shows little stabilization of the i-motif. From several selected DNA-binding ligands, the G-quadruplex ligand BA41 is shown to interact with the duplex moiety, whereas non-specific interaction and little stabilization has been observed within the i-motif.
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Affiliation(s)
- Judit Rodriguez
- Department of Chemical Engineering and Analytical Chemistry, Faculty of Chemistry, University of Barcelona, Marti i Franqués 1-11, E-08028 Barcelona, Spain
| | - Arnau Domínguez
- Institute for Advanced Chemistry of Catalonia (IQAC), CSIC, Networking Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain
| | - Anna Aviñó
- Institute for Advanced Chemistry of Catalonia (IQAC), CSIC, Networking Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain
| | - Gigliola Borgonovo
- Department of Food, Environmental and Nutritional Sciences (DEFENS), University of Milan (Università degli Studi di Milano), Milan, Italy
| | - Ramon Eritja
- Institute for Advanced Chemistry of Catalonia (IQAC), CSIC, Networking Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain
| | - Stefania Mazzini
- Department of Food, Environmental and Nutritional Sciences (DEFENS), University of Milan (Università degli Studi di Milano), Milan, Italy
| | - Raimundo Gargallo
- Department of Chemical Engineering and Analytical Chemistry, Faculty of Chemistry, University of Barcelona, Marti i Franqués 1-11, E-08028 Barcelona, Spain.
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22
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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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23
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Petrunina NA, Shtork AS, Lukina MM, Tsvetkov VB, Khodarovich YM, Feofanov AV, Moysenovich AM, Maksimov EG, Shipunova VO, Zatsepin TS, Bogomazova AN, Shender VO, Aralov AV, Lagarkova MA, Varizhuk AM. Ratiometric i-Motif-Based Sensor for Precise Long-Term Monitoring of pH Micro Alterations in the Nucleoplasm and Interchromatin Granules. ACS Sens 2023; 8:619-629. [PMID: 36662613 DOI: 10.1021/acssensors.2c01813] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
DNA-intercalated motifs (iMs) are facile scaffolds for the design of various pH-responsive nanomachines, including biocompatible pH sensors. First, DNA pH sensors relied on complex intermolecular scaffolds. Here, we used a simple unimolecular dual-labeled iM scaffold and minimized it by replacing the redundant loop nucleosides with abasic or alkyl linkers. These modifications improved the thermal stability of the iM and increased the rates of its pH-induced conformational transitions. The best effects were obtained upon the replacement of all three native loops with short and flexible linkers, such as the propyl one. The resulting sensor showed a pH transition value equal to 6.9 ± 0.1 and responded rapidly to minor acidification (tau1/2 <1 s for 7.2 → 6.6 pH jump). We demonstrated the applicability of this sensor for pH measurements in the nuclei of human lung adenocarcinoma cells (pH = 7.4 ± 0.2) and immortalized embryonic kidney cells (pH = 7.0 ± 0.2). The sensor stained diffusely the nucleoplasm and piled up in interchromatin granules. These findings highlight the prospects of iMs in the studies of normal and pathological pH-dependent processes in the nucleus, including the formation of biomolecular condensates.
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Affiliation(s)
- Nataliia A Petrunina
- Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow119435, Russia
| | - Alina S Shtork
- Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow119435, Russia
| | - Maria M Lukina
- Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow119435, Russia.,Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow119435, Russia
| | - Vladimir B Tsvetkov
- Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow119435, Russia.,Institute of Biodesign and Complex System Modeling, I.M. Sechenov First Moscow State Medical University, Moscow119991, Russia.,A.V. Topchiev Institute of Petrochemical Synthesis RAS, Leninsky Prospect Str. 29, Moscow119991, Russia
| | - Yuri M Khodarovich
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow117997, Russia.,The Peoples' Friendship University of Russia, 117198Moscow, Russia
| | - Alexey V Feofanov
- Biological Faculty, Lomonosov Moscow State University, Moscow119992, Russia.,Institute of Gene Biology RAS, Russian Academy of Sciences, Moscow119334, Russia
| | | | - Eugene G Maksimov
- Biological Faculty, Lomonosov Moscow State University, Moscow119992, Russia
| | - Victoria O Shipunova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow117997, Russia
| | - Timofei S Zatsepin
- Department of Chemistry, Lomonosov Moscow State University, Moscow119992, Russia
| | - Alexandra N Bogomazova
- Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow119435, Russia.,Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow119435, Russia
| | - Victoria O Shender
- Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow119435, Russia.,Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow119435, Russia.,Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow117997, Russia
| | - Andrey V Aralov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow117997, Russia
| | - Maria A Lagarkova
- Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow119435, Russia.,Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow119435, Russia
| | - Anna M Varizhuk
- Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow119435, Russia.,Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow119435, Russia.,G4_Interact, USERN, University of Pavia, 27100Pavia, Italy
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24
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i-Motif folding intermediates with zero-nucleotide loops are trapped by 2'-fluoroarabinocytidine via F···H and O···H hydrogen bonds. Commun Chem 2023; 6:31. [PMID: 36797370 PMCID: PMC9935537 DOI: 10.1038/s42004-023-00831-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 02/03/2023] [Indexed: 02/18/2023] Open
Abstract
G-quadruplex and i-motif nucleic acid structures are believed to fold through kinetic partitioning mechanisms. Such mechanisms explain the structural heterogeneity of G-quadruplex metastable intermediates which have been extensively reported. On the other hand, i-motif folding is regarded as predictable, and research on alternative i-motif folds is limited. While TC5 normally folds into a stable tetrameric i-motif in solution, we report that 2'-deoxy-2'-fluoroarabinocytidine (araF-C) substitutions can prompt TC5 to form an off-pathway and kinetically-trapped dimeric i-motif, thereby expanding the scope of i-motif folding landscapes. This i-motif is formed by two strands, associated head-to-head, and featuring zero-nucleotide loops which have not been previously observed. Through spectroscopic and computational analyses, we also establish that the dimeric i-motif is stabilized by fluorine and non-fluorine hydrogen bonds, thereby explaining the superlative stability of araF-C modified i-motifs. Comparative experimental findings suggest that the strength of these interactions depends on the flexible sugar pucker adopted by the araF-C residue. Overall, the findings reported here provide a new role for i-motifs in nanotechnology and also pose the question of whether unprecedented i-motif folds may exist in vivo.
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25
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Serrano-Chacón I, Mir B, Cupellini L, Colizzi F, Orozco M, Escaja N, González C. pH-Dependent Capping Interactions Induce Large-Scale Structural Transitions in i-Motifs. J Am Chem Soc 2023; 145:3696-3705. [PMID: 36745195 PMCID: PMC9936585 DOI: 10.1021/jacs.2c13043] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Indexed: 02/07/2023]
Abstract
We study here a DNA oligonucleotide having the ability to form two different i-motif structures whose relative stability depends on pH and temperature. The major species at neutral pH is stabilized by two C:C+ base pairs capped by two minor groove G:C:G:C tetrads. The high pH and thermal stability of this structure are mainly due to the favorable effect of the minor groove tetrads on their adjacent positively charged C:C+ base pairs. At pH 5, we observe a more elongated i-motif structure consisting of four C:C+ base pairs capped by two G:T:G:T tetrads. Molecular dynamics calculations show that the conformational transition between the two structures is driven by the protonation state of key cytosines. In spite of large conformational differences, the transition between the acidic and neutral structures can occur without unfolding of the i-motif. These results represent the first case of a conformational switch between two different i-motif structures and illustrate the dramatic pH-dependent plasticity of this fascinating DNA motif.
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Affiliation(s)
- Israel Serrano-Chacón
- Instituto
de Química Física ”Rocasolano”, CSIC, Serrano 119, 28006Madrid, Spain
- Institute
for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), 08028Barcelona, Spain
| | - Bartomeu Mir
- Instituto
de Química Física ”Rocasolano”, CSIC, Serrano 119, 28006Madrid, Spain
- Inorganic
and Organic Chemistry Department, Organic Chemistry Section, and IBUB, University of Barcelona, Martí i Franquès 1-11, 08028Barcelona, Spain
| | - Lorenzo Cupellini
- Institute
for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), 08028Barcelona, Spain
| | - Francesco Colizzi
- Institute
for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), 08028Barcelona, Spain
| | - Modesto Orozco
- Institute
for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), 08028Barcelona, Spain
- Departament
de Bioquímica i Biomedicina. Facultat de Biologia, Universitat de Barcelona, 08028Barcelona, Spain
| | - Núria Escaja
- Inorganic
and Organic Chemistry Department, Organic Chemistry Section, and IBUB, University of Barcelona, Martí i Franquès 1-11, 08028Barcelona, Spain
- BIOESTRAN
Associated Unit UB-CSIC, 08028Barcelona, Spain
| | - Carlos González
- Instituto
de Química Física ”Rocasolano”, CSIC, Serrano 119, 28006Madrid, Spain
- BIOESTRAN
Associated Unit UB-CSIC, 08028Barcelona, Spain
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26
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Bekkouche I, Shishonin AY, Vetcher AA. Recent Development in Biomedical Applications of Oligonucleotides with Triplex-Forming Ability. Polymers (Basel) 2023; 15:polym15040858. [PMID: 36850142 PMCID: PMC9964087 DOI: 10.3390/polym15040858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 01/31/2023] [Accepted: 02/02/2023] [Indexed: 02/12/2023] Open
Abstract
A DNA structure, known as triple-stranded DNA, is made up of three oligonucleotide chains that wind around one another to form a triple helix (TFO). Hoogsteen base pairing describes how triple-stranded DNA may be built at certain conditions by the attachment of the third strand to an RNA, PNA, or DNA, which might all be employed as oligonucleotide chains. In each of these situations, the oligonucleotides can be employed as an anchor, in conjunction with a specific bioactive chemical, or as a messenger that enables switching between transcription and replication through the triplex-forming zone. These data are also considered since various illnesses have been linked to the expansion of triplex-prone sequences. In light of metabolic acidosis and associated symptoms, some consideration is given to the impact of several low-molecular-weight compounds, including pH on triplex production in vivo. The review is focused on the development of biomedical oligonucleotides with triplexes.
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Affiliation(s)
- Incherah Bekkouche
- Nanotechnology Scientific and Educational Center, Institute of Biochemical Technology and Nanotechnology, Peoples’ Friendship University of Russia (RUDN), Miklukho-Maklaya Str. 6, Moscow 117198, Russia
| | - Alexander Y. Shishonin
- Complementary and Integrative Health Clinic of Dr. Shishonin, 5, Yasnogorskaya Str., Moscow 117588, Russia
| | - Alexandre A. Vetcher
- Nanotechnology Scientific and Educational Center, Institute of Biochemical Technology and Nanotechnology, Peoples’ Friendship University of Russia (RUDN), Miklukho-Maklaya Str. 6, Moscow 117198, Russia
- Complementary and Integrative Health Clinic of Dr. Shishonin, 5, Yasnogorskaya Str., Moscow 117588, Russia
- Correspondence:
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27
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Gong X, Lin X, Wang S, Ji D, Shu B, Huang ZS, Li D. Regulation of c-Kit gene transcription selectively by bisacridine derivative through promoter dual i-motif structures. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2023; 1866:194912. [PMID: 36754277 DOI: 10.1016/j.bbagrm.2023.194912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 01/16/2023] [Accepted: 02/02/2023] [Indexed: 02/09/2023]
Abstract
BACKGROUND c-Kit protein is a signal transduction protein involved in multiple signal pathways, which play an important role in a variety of cellular events such as cell proliferation, apoptosis and differentiation. Special DNA secondary structures on the promoter of c-Kit gene, including G-quadruplex and i-motif structures, could act as "molecular switch" for gene transcriptional regulation, which are potentially important target for development of new anti-cancer drugs. METHODS We screened and evaluated the effect of compounds on c-Kit through several experiments, including SPR, FRET, CD, MST, NMR, dual-luciferase reporter assay, Western blot, qPCR, immunofluorescence, MTT assay, colony formation, cell scrape, cell apoptosis, cell cycle analysis, and transwell assay. RESULTS After extensive screening, we found that bisacridine derivative B05 had selective binding and stabilization to dual i-motif structures on c-Kit gene promoter, which could down-regulate c-Kit gene transcription and translation, resulting in inhibition of cell proliferation and metastasis. B05 exhibited potent anti-tumor activity on HGC-27 cells, and strongly suppressed tumor growth in HGC-27 xenograft mice model. CONCLUSIONS B05 could interact with c-Kit promoter dual i-motif structures with excellent selectivity, which make it possible for selective regulation of gene transcription and translation. B05 could be further developed for selective anti-cancer agent targeting c-Kit promoter i-motifs. GENERAL SIGNIFICANCE i-Motifs on different proto-oncogene promoters are diversified, and especially binding of dual i-motifs on the same promoter simultaneously could significantly down-regulate gene transcription with decreased dosage, and therefore increasing the selectivity. This new strategy shed bight light on development of selective DNA-targeting ligands.
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Affiliation(s)
- Xue Gong
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, Guangzhou, PR China
| | - Xiaomin Lin
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, Guangzhou, PR China
| | - Siyi Wang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, Guangzhou, PR China
| | - Dongsheng Ji
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, Guangzhou, PR China
| | - Bing Shu
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, Guangzhou, PR China; School of Pharmacy, Guangdong Pharmaceutical University, Guangzhou, PR China
| | - Zhi-Shu Huang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, Guangzhou, PR China
| | - Ding Li
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, Guangzhou, PR China.
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28
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Berthiol F, Boissieras J, Bonnet H, Pierrot M, Philouze C, Poisson JF, Granzhan A, Dejeu J, Defrancq E. Novel Synthesis of IMC-48 and Affinity Evaluation with Different i-Motif DNA Sequences. Molecules 2023; 28:molecules28020682. [PMID: 36677740 PMCID: PMC9865601 DOI: 10.3390/molecules28020682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 01/04/2023] [Accepted: 01/05/2023] [Indexed: 01/12/2023] Open
Abstract
During the last decade, the evidence for the biological relevance of i-motif DNA (i-DNA) has been accumulated. However, relatively few molecules were reported to interact with i-DNA, and a controversy concerning their binding mode, affinity, and selectivity persists in the literature. In this context, the cholestane derivative IMC-48 has been reported to modulate bcl-2 gene expression by stabilizing an i-motif structure in its promoter. In the present contribution, we report on a novel, more straightforward, synthesis of IMC-48 requiring fewer steps compared to the previous approach. Furthermore, the interaction of IMC-48 with four different i-motif DNA sequences was thoroughly investigated by bio-layer interferometry (BLI) and circular dichroism (CD) spectroscopy. Surprisingly, our results show that IMC-48 is a very weak ligand of i-DNA as no quantifiable interaction or significant stabilization of i-motif structures could be observed, stimulating a quest for an alternative mechanism of its biological activity.
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Affiliation(s)
- Florian Berthiol
- Department of Molecular Chemistry (DCM), CNRS, UMR 5250, Université Grenoble-Alpes, 38000 Grenoble, France
- Correspondence: (F.B.); (J.D.); (E.D.)
| | - Joseph Boissieras
- CNRS UMR9187, INSERM U1196, Institut Curie, PSL Research University, F-91405 Orsay, France
- CNRS UMR9187, INSERM U1196, Université Paris Saclay, F-91405 Orsay, France
| | - Hugues Bonnet
- Department of Molecular Chemistry (DCM), CNRS, UMR 5250, Université Grenoble-Alpes, 38000 Grenoble, France
| | - Marie Pierrot
- Department of Molecular Chemistry (DCM), CNRS, UMR 5250, Université Grenoble-Alpes, 38000 Grenoble, France
| | - Christian Philouze
- Department of Molecular Chemistry (DCM), CNRS, UMR 5250, Université Grenoble-Alpes, 38000 Grenoble, France
| | - Jean-François Poisson
- Department of Molecular Chemistry (DCM), CNRS, UMR 5250, Université Grenoble-Alpes, 38000 Grenoble, France
| | - Anton Granzhan
- CNRS UMR9187, INSERM U1196, Institut Curie, PSL Research University, F-91405 Orsay, France
- CNRS UMR9187, INSERM U1196, Université Paris Saclay, F-91405 Orsay, France
| | - Jérôme Dejeu
- Department of Molecular Chemistry (DCM), CNRS, UMR 5250, Université Grenoble-Alpes, 38000 Grenoble, France
- FEMTO-ST Institute, CNRS UMR-6174, Université de Bourgogne Franche-Comté, F-25000 Besançon, France
- Correspondence: (F.B.); (J.D.); (E.D.)
| | - Eric Defrancq
- Department of Molecular Chemistry (DCM), CNRS, UMR 5250, Université Grenoble-Alpes, 38000 Grenoble, France
- Correspondence: (F.B.); (J.D.); (E.D.)
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29
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Eladl O, Yamaoki Y, Kondo K, Nagata T, Katahira M. Detection of interaction between an RNA aptamer and its target compound in living human cells using 2D in-cell NMR. Chem Commun (Camb) 2022; 59:102-105. [PMID: 36475447 DOI: 10.1039/d2cc05576g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We introduced an isotopically labeled RNA aptamer for HIV-1 Tat prepared by E. coli transcription into HeLa cells. We successfully recorded the first heteronuclear 2D in-cell NMR spectra, which makes it possible to study the interaction of the RNA aptamer with argininamide in living human cells with higher resolution.
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Affiliation(s)
- Omar Eladl
- Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan. .,Graduate School of Energy Science, Kyoto University, Yoshida-hommachi, Sakyo-ku, Kyoto 606-8501, Japan.,Faculty of Pharmacy, Zagazig University, Zagazig 44519, Egypt
| | - Yudai Yamaoki
- Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan. .,Graduate School of Energy Science, Kyoto University, Yoshida-hommachi, Sakyo-ku, Kyoto 606-8501, Japan
| | - Keiko Kondo
- Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan.
| | - Takashi Nagata
- Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan. .,Graduate School of Energy Science, Kyoto University, Yoshida-hommachi, Sakyo-ku, Kyoto 606-8501, Japan
| | - Masato Katahira
- Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan. .,Graduate School of Energy Science, Kyoto University, Yoshida-hommachi, Sakyo-ku, Kyoto 606-8501, Japan
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30
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Shedding light on the base-pair opening dynamics of nucleic acids in living human cells. Nat Commun 2022; 13:7143. [PMID: 36446768 PMCID: PMC9708698 DOI: 10.1038/s41467-022-34822-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 11/03/2022] [Indexed: 11/30/2022] Open
Abstract
Base-pair opening is a fundamental property of nucleic acids that plays important roles in biological functions. However, studying the base-pair opening dynamics inside living cells has remained challenging. Here, to determine the base-pair opening kinetics inside living human cells, the exchange rate constant ([Formula: see text]) of the imino proton with the proton of solvent water involved in hairpin and G-quadruplex (GQ) structures is determined by the in-cell NMR technique. It is deduced on determination of [Formula: see text] values that at least some G-C base pairs of the hairpin structure and all G-G base-pairs of the GQ structure open more frequently in living human cells than in vitro. It is suggested that interactions with endogenous proteins could be responsible for the increase in frequency of base-pair opening. Our studies demonstrate a difference in dynamics of nucleic acids between in-cell and in vitro conditions.
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31
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Mechanistic insights into poly(C)-binding protein hnRNP K resolving i-motif DNA secondary structures. J Biol Chem 2022; 298:102670. [PMID: 36334628 PMCID: PMC9709238 DOI: 10.1016/j.jbc.2022.102670] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 10/26/2022] [Accepted: 10/30/2022] [Indexed: 11/27/2022] Open
Abstract
I-motifs are four-strand noncanonical secondary structures formed by cytosine (C)-rich sequences in living cells. The structural dynamics of i-motifs play essential roles in many cellular processes, such as telomerase inhibition, DNA replication, and transcriptional regulation. In cells, the structural dynamics of the i-motif can be modulated by the interaction of poly(C)-binding proteins (PCBPs), and the interaction is closely related to human health, through modulating the transcription of oncogenes and telomere stability. Therefore, the mechanisms of how PCBPs interact with i-motif structures are fundamentally important. However, the underlying mechanisms remain elusive. I-motif structures in the promoter of the c-MYC oncogene can be unfolded by heterogeneous nuclear ribonucleoprotein K (hnRNP K), a PCBP, to activate its transcription. Here, we selected this system as an example to comprehensively study the unfolding mechanisms. We found that the promoter sequence containing 5 C-runs preferred folding into type-1245 to type-1234 i-motif structures based on their folding stability, which was further confirmed by single-molecule FRET. In addition, we first revealed that the c-MYC i-motif structure was discretely resolved by hnRNP K through two intermediate states, which were assigned to the opposite hairpin and neighboring hairpin, as further confirmed by site mutations. Furthermore, we found all three KH (hnRNP K homology) domains of hnRNP K could unfold the c-MYC i-motif structure, and KH2 and KH3 were more active than KH1. In conclusion, this study may deepen our understanding of the interactions between i-motifs and PCBPs and may be helpful for drug development.
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32
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Yang T, Xu Q, Chen J, Jia PK, Xie BB, Wang D, Zhou X, Shao Y. Selectively Identifying Exposed-over-Unexposed C-C + Pairs in Human Telomeric i-Motif Structures with Length-Dependent Polymorphism. Anal Chem 2022; 94:14994-15001. [PMID: 36263663 DOI: 10.1021/acs.analchem.2c02875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The i-motif structure (iM) has attracted much attention, because of its in vivo bioactivity and wide in vitro applications such as DNA-based switches. Herein, the length-dependent folding of cytosine-rich repeats of the human telomeric 5'-(CCCTAA)n-1CCC-3' (iM-n, where n = 2-8) was fully explored. We found that iM-4, iM-5, and iM-8 mainly form the intramolecular monomer iM structures, while a tetramolecular structure populates only for iM-3. However, iM-6 and iM-7 have the potential to fold as well into the dimeric iM structures besides the monomer ones. The natural hypericin (Hyp) was used as the polymorphism-selective probe to recognize the iM structures. Interestingly, only iM-3, iM-6, and iM-7 can efficiently switch on the Hyp fluorescence by specifically binding with the outmost C-C+ base pairs that are exposed directly to solution. However, other iM structures that fold in a way with a coverage of the outmost C-C+ pairs by loop sequences are totally unavailable for the Hyp binding. Theoretical modeling indicates that adaptive π-π and cation-π interactions contribute to the Hyp recognition toward the exposed C-C+ pairs. This specific iM recognition can be boosted by a photocatalytic DNAzyme construct. Our work provides a reliable fluorescence method to selectively explore the polymorphism of iM structures.
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Affiliation(s)
- Tong Yang
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, People's Republic of China
| | - Qiuda Xu
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, People's Republic of China
| | - Jiahui Chen
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, People's Republic of China
| | - Pei-Ke Jia
- Hangzhou Institute of Advanced Studies, Zhejiang Normal University, 1108 Gengwen Road, Hangzhou 311231, Zhejiang, People's Republic of China
| | - Bin-Bin Xie
- Hangzhou Institute of Advanced Studies, Zhejiang Normal University, 1108 Gengwen Road, Hangzhou 311231, Zhejiang, People's Republic of China
| | - Dandan Wang
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, People's Republic of China
| | - Xiaoshun Zhou
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, People's Republic of China
| | - Yong Shao
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, People's Republic of China
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Theillet FX, Luchinat E. In-cell NMR: Why and how? PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2022; 132-133:1-112. [PMID: 36496255 DOI: 10.1016/j.pnmrs.2022.04.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 04/19/2022] [Accepted: 04/27/2022] [Indexed: 06/17/2023]
Abstract
NMR spectroscopy has been applied to cells and tissues analysis since its beginnings, as early as 1950. We have attempted to gather here in a didactic fashion the broad diversity of data and ideas that emerged from NMR investigations on living cells. Covering a large proportion of the periodic table, NMR spectroscopy permits scrutiny of a great variety of atomic nuclei in all living organisms non-invasively. It has thus provided quantitative information on cellular atoms and their chemical environment, dynamics, or interactions. We will show that NMR studies have generated valuable knowledge on a vast array of cellular molecules and events, from water, salts, metabolites, cell walls, proteins, nucleic acids, drugs and drug targets, to pH, redox equilibria and chemical reactions. The characterization of such a multitude of objects at the atomic scale has thus shaped our mental representation of cellular life at multiple levels, together with major techniques like mass-spectrometry or microscopies. NMR studies on cells has accompanied the developments of MRI and metabolomics, and various subfields have flourished, coined with appealing names: fluxomics, foodomics, MRI and MRS (i.e. imaging and localized spectroscopy of living tissues, respectively), whole-cell NMR, on-cell ligand-based NMR, systems NMR, cellular structural biology, in-cell NMR… All these have not grown separately, but rather by reinforcing each other like a braided trunk. Hence, we try here to provide an analytical account of a large ensemble of intricately linked approaches, whose integration has been and will be key to their success. We present extensive overviews, firstly on the various types of information provided by NMR in a cellular environment (the "why", oriented towards a broad readership), and secondly on the employed NMR techniques and setups (the "how", where we discuss the past, current and future methods). Each subsection is constructed as a historical anthology, showing how the intrinsic properties of NMR spectroscopy and its developments structured the accessible knowledge on cellular phenomena. Using this systematic approach, we sought i) to make this review accessible to the broadest audience and ii) to highlight some early techniques that may find renewed interest. Finally, we present a brief discussion on what may be potential and desirable developments in the context of integrative studies in biology.
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Affiliation(s)
- Francois-Xavier Theillet
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France.
| | - Enrico Luchinat
- Dipartimento di Scienze e Tecnologie Agro-Alimentari, Alma Mater Studiorum - Università di Bologna, Piazza Goidanich 60, 47521 Cesena, Italy; CERM - Magnetic Resonance Center, and Neurofarba Department, Università degli Studi di Firenze, 50019 Sesto Fiorentino, Italy
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Bansal A, Kaushik S, Kukreti S. Non-canonical DNA structures: Diversity and disease association. Front Genet 2022; 13:959258. [PMID: 36134025 PMCID: PMC9483843 DOI: 10.3389/fgene.2022.959258] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 07/25/2022] [Indexed: 11/18/2022] Open
Abstract
A complete understanding of DNA double-helical structure discovered by James Watson and Francis Crick in 1953, unveil the importance and significance of DNA. For the last seven decades, this has been a leading light in the course of the development of modern biology and biomedical science. Apart from the predominant B-form, experimental shreds of evidence have revealed the existence of a sequence-dependent structural diversity, unusual non-canonical structures like hairpin, cruciform, Z-DNA, multistranded structures such as DNA triplex, G-quadruplex, i-motif forms, etc. The diversity in the DNA structure depends on various factors such as base sequence, ions, superhelical stress, and ligands. In response to these various factors, the polymorphism of DNA regulates various genes via different processes like replication, transcription, translation, and recombination. However, altered levels of gene expression are associated with many human genetic diseases including neurological disorders and cancer. These non-B-DNA structures are expected to play a key role in determining genetic stability, DNA damage and repair etc. The present review is a modest attempt to summarize the available literature, illustrating the occurrence of non-canonical structures at the molecular level in response to the environment and interaction with ligands and proteins. This would provide an insight to understand the biological functions of these unusual DNA structures and their recognition as potential therapeutic targets for diverse genetic diseases.
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Affiliation(s)
- Aparna Bansal
- Nucleic Acid Research Lab, Department of Chemistry, University of Delhi, Delhi, India
- Department of Chemistry, Hansraj College, University of Delhi, Delhi, India
| | - Shikha Kaushik
- Nucleic Acid Research Lab, Department of Chemistry, University of Delhi, Delhi, India
- Department of Chemistry, Rajdhani College, University of Delhi, New Delhi, India
| | - Shrikant Kukreti
- Nucleic Acid Research Lab, Department of Chemistry, University of Delhi, Delhi, India
- *Correspondence: Shrikant Kukreti,
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Khamari L, Mukherjee S. Deciphering the Nanoconfinement Effect on the Folding Pathway of c-MYC Promoter-Based Intercalated-Motif DNA by Single-Molecule Förster Resonance Energy Transfer. J Phys Chem Lett 2022; 13:8169-8176. [PMID: 36005552 DOI: 10.1021/acs.jpclett.2c01893] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Intercalated-motif (i-motif) DNA formed by cytosine (C)-rich sequences has been considered a novel target in anticancer research. Interestingly, this type of noncanonical DNA structure is highly dynamic and can display several conformational polymorphisms based on the immediate surrounding environment. However, studies regarding the folding pathway of i-motifs having disease-specific sequences under a confined environment at physiological pH are relatively scarce. This thereby warrants more explorations that will decipher their structural and functional properties inside constrained media. Herein, using the single-molecule Förster Resonance Energy Transfer (smFRET) studies, for the first time, we have illustrated the conformational dynamics of c-MYC promoter-based i-motif structures at physiological pH inside microemulsions of different dimensions. We concluded that the folding of such motifs under confined space is not a direct transition between the random coil and i-motif conformations; rather it occurs through a partially folded intermediate, depending on the confined dimension.
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Affiliation(s)
- Laxmikanta Khamari
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal Bypass Road, Bhauri, Bhopal 462 066, Madhya Pradesh, India
| | - Saptarshi Mukherjee
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal Bypass Road, Bhauri, Bhopal 462 066, Madhya Pradesh, India
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Mustafa G, Gyawali P, Taylor JA, Maleki P, Nunez MV, Guntrum MC, Shiekh S, Balci H. A single molecule investigation of i-motif stability, folding intermediates, and potential as in-situ pH sensor. Front Mol Biosci 2022; 9:977113. [PMID: 36072435 PMCID: PMC9441956 DOI: 10.3389/fmolb.2022.977113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 07/26/2022] [Indexed: 11/13/2022] Open
Abstract
We present a collection of single molecule work on the i-motif structure formed by the human telomeric sequence. Even though it was largely ignored in earlier years of its discovery due to its modest stability and requirement for low pH levels (pH < 6.5), the i-motif has been attracting more attention recently as both a physiologically relevant structure and as a potent pH sensor. In this manuscript, we establish single molecule Förster resonance energy transfer (smFRET) as a tool to study the i-motif over a broad pH and ionic conditions. We demonstrate pH and salt dependence of i-motif formation under steady state conditions and illustrate the intermediate states visited during i-motif folding in real time at the single molecule level. We also show the prominence of intermediate folding states and reversible folding/unfolding transitions. We present an example of using the i-motif as an in-situ pH sensor and use this sensor to establish the time scale for the pH drop in a commonly used oxygen scavenging system.
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Khatik SY, Srivatsan SG. Environment-Sensitive Nucleoside Probe Unravels the Complex Structural Dynamics of i-Motif DNAs. Bioconjug Chem 2022; 33:1515-1526. [PMID: 35819865 DOI: 10.1021/acs.bioconjchem.2c00237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Although evidence for the existence and biological role of i-motif (iM) DNA structures in cells is emerging, probing their structural polymorphism and identifying physiologically active conformations using currently available tools remain a major challenge. Here, we describe the development of an innovative device to investigate the conformation equilibrium of different iMs formed by C-rich telomeric repeat and oncogenic B-raf promoter sequences using a new conformation-sensitive dual-purpose nucleoside probe. The nucleoside is composed of a trifluoromethyl-benzofuran-2-yl moiety at the C5 position of 2'-deoxyuridine, which functions as a responsive fluorescent and 19F NMR probe. While the fluorescent component is useful in monitoring and estimating the folding process, the 19F label provides spectral signatures for various iMs, thereby enabling a systematic analysis of their complex population equilibrium under different conditions (e.g., pH, temperature, metal ions, and cell lysate). Distinct 19F signals exhibited by the iMs formed by the human telomeric repeat helped in calculating their relative population. A battery of fluorescence and 19F NMR studies using native and mutated B-raf oligonucleotides gave valuable insights into the iM structure landscape and its dependence on environmental conditions and also helped in predicting the structure of the major iM conformation. Overall, our findings indicate that the probe is highly suitable for studying complex nucleic acid systems.
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Affiliation(s)
- Saddam Y Khatik
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune, Dr. Homi Bhabha Road, Pune 411008, India
| | - Seergazhi G Srivatsan
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune, Dr. Homi Bhabha Road, Pune 411008, India
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CpG Methylation Altered the Stability and Structure of the i-Motifs Located in the CpG Islands. Int J Mol Sci 2022; 23:ijms23126467. [PMID: 35742916 PMCID: PMC9223787 DOI: 10.3390/ijms23126467] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 06/04/2022] [Accepted: 06/07/2022] [Indexed: 11/25/2022] Open
Abstract
Cytosine methylation within the 5′-C-phosphate-G-3′ sequence of nucleotides (called CpG methylation) is a well-known epigenetic modification of genomic DNA that plays an important role in gene expression and development. CpG methylation is likely to be altered in the CpG islands. CpG islands are rich in cytosine, forming a structure called the i-motif via cytosine-cytosine hydrogen bonding. However, little is known about the effect of CpG methylation on the i-motif. In this study, The CpG methylation-induced structural changes on the i-motif was examined by thermal stability, circular dichroism (CD) spectroscopy, and native-polyacrylamide gel electrophoresis (Native-PAGE) evaluation of five i-motif-forming DNAs from four cancer-related genes (VEGF, C-KIT, BCL2, and HRAS). This research shows that CpG methylation increased the transitional pH of several i-motif-forming DNAs and their thermal stability. When examining the effect of CpG methylation on the i-motif in the presence of opposite G4-forming DNAs, CpG methylation influenced the proportion of G4 and i-motif formation. This study showed that CpG methylation altered the stability and structure of the i-motif in CpG islands.
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Bonnet H, Morel M, Devaux A, Boissieras J, Granzhan A, Elias B, Lavergne T, Dejeu J, Defrancq E. Assessment of presumed small-molecule ligands of telomeric i-DNA by biolayer interferometry (BLI). Chem Commun (Camb) 2022; 58:5116-5119. [PMID: 35380138 DOI: 10.1039/d2cc00836j] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Biolayer interferometry (BLI) and circular dichroism (CD) spectroscopy were used to investigate the interaction between previously reported i-motif DNA (i-DNA) ligands and folded or unfolded i-DNA in acidic (pH 5.5) and near-neutral (pH 6.5) conditions. We observed that although several ligands, in particular macrocyclic bis-acridine (BisA) and pyridostatin (PDS), showed good affinities for the telomeric i-motif forming sequence, none of the ligands displayed selective interactions with the i-DNA structure nor was able to promote its formation.
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Affiliation(s)
- Hugues Bonnet
- Université Grenoble Alpes, Département de Chimie Moléculaire, UMR CNRS 5250, CS 40700-38058 Grenoble, France.
| | - Maéva Morel
- Université Grenoble Alpes, Département de Chimie Moléculaire, UMR CNRS 5250, CS 40700-38058 Grenoble, France.
| | - Alexandre Devaux
- Université Grenoble Alpes, Département de Chimie Moléculaire, UMR CNRS 5250, CS 40700-38058 Grenoble, France.
| | - Joseph Boissieras
- Institut Curie, CNRS UMR 9187, INSERM U1196, Université Paris Saclay, 91405 Orsay, France
| | - Anton Granzhan
- Institut Curie, CNRS UMR 9187, INSERM U1196, Université Paris Saclay, 91405 Orsay, France
| | - Benjamin Elias
- Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Université catholique de Louvain (UCLouvain), Place Louis Pasteur 1, 1348 Louvain-la-Neuve, Belgium
| | - Thomas Lavergne
- Université Grenoble Alpes, Département de Chimie Moléculaire, UMR CNRS 5250, CS 40700-38058 Grenoble, France.
| | - Jérôme Dejeu
- Université Grenoble Alpes, Département de Chimie Moléculaire, UMR CNRS 5250, CS 40700-38058 Grenoble, France. .,FEMTO-ST Institute, CNRS UMR-6174, Université de Bourgogne Franche-Comté, F-25000 Besançon, France
| | - Eric Defrancq
- Université Grenoble Alpes, Département de Chimie Moléculaire, UMR CNRS 5250, CS 40700-38058 Grenoble, France.
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Umar MI, Chan CY, Kwok CK. Development of RNA G-quadruplex (rG4)-targeting L-RNA aptamers by rG4-SELEX. Nat Protoc 2022; 17:1385-1414. [PMID: 35444329 DOI: 10.1038/s41596-022-00679-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 12/15/2021] [Indexed: 11/09/2022]
Abstract
RNA G-quadruplex (rG4)-SELEX is a method that generates L-RNA aptamers to target an rG4 structure of interest, which can be applied to inhibit G-quadruplex-mediated interactions that have important roles in gene regulation and function. Here we present a Protocol Extension substantially modifying an existing SELEX protocol to describe in detail the procedures involved in performing rG4-SELEX to identify rG4-specific binders that can effectively suppress rG4-peptide and rG4-protein associations. This Protocol Extension improves the speed of aptamer discovery and identification, offering a suite of techniques to characterize the aptamer secondary structure and monitor binding affinity and specificity, and demonstrating the utility of the L-RNA aptamer. The previous protocol mainly describes the identification of RNA aptamers against proteins of interest, whereas in this Protocol Extension we present the development of an unnatural RNA aptamer against an RNA structure of interest, with the potential to be applicable to other nucleic acid motifs or biomolecules. rG4-SELEX starts with a random D-RNA library incubated with the L-rG4 target of interest, followed by binding, washing and elution of the library. Enriched D-aptamer candidates are sequenced and structurally characterized. Then, the L-aptamer is synthesized and used for different applications. rG4-SELEX can be carried out by an experienced molecular biologist with a basic understanding of nucleic acids. The development of rG4-targeting L-RNA aptamers expands the current rG4 toolkit to explore innovative rG4-related applications, and opens new doors to discovering novel rG4 biology in the near future. The duration of each selection cycle as outlined in the protocol is ~2 d.
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Affiliation(s)
- Mubarak I Umar
- Department of Chemistry and State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China.,RNA Molecular Biology Group, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health, Bethesda, MD, USA
| | - Chun-Yin Chan
- Department of Chemistry and State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China.,Institut für Chemische Epigenetik München (ICEM), Ludwig-Maximilians-Universtität München, Munich, Germany
| | - Chun Kit Kwok
- Department of Chemistry and State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China. .,Shenzhen Research Institute of City University of Hong Kong, Shenzhen, China.
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Jamroskovic J, Deiana M, Sabouri N. Probing the folding pathways of four-stranded intercalated cytosine-rich motifs at single base-pair resolution. Biochimie 2022; 199:81-91. [PMID: 35452743 DOI: 10.1016/j.biochi.2022.04.007] [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: 03/06/2022] [Revised: 04/13/2022] [Accepted: 04/13/2022] [Indexed: 11/24/2022]
Abstract
Cytosine-rich DNA can fold into four-stranded intercalated structures called i-motifs (iMs) under acidic conditions through the formation of hemi-protonated C:C+ base pairs. However, the folding and stability of iMs rely on many other factors that are not yet fully understood. Here, we combined biochemical and biophysical approaches to determine the factors influencing iM stability under a wide range of experimental conditions. By using high-resolution primer extension assays, circular dichroism, and absorption spectroscopies, we demonstrate that the stabilities of three different biologically relevant iMs are not dependent on molecular crowding agents. Instead, some of the crowding agents affected overall DNA synthesis. We also tested a range of small molecules to determine their effect on iM stabilization at physiological temperature and demonstrated that the G-quadruplex-specific molecule CX-5461 is also a promising candidate for selective iM stabilization. This work provides important insights into the requirements needed for different assays to accurately study iM stabilization, which will serve as important tools for understanding the contribution of iMs in cell regulation and their potential as therapeutic targets.
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Affiliation(s)
- Jan Jamroskovic
- Department of Medical Biochemistry and Biophysics, Umeå University, 901 87, Umeå, Sweden.
| | - Marco Deiana
- Department of Medical Biochemistry and Biophysics, Umeå University, 901 87, Umeå, Sweden
| | - Nasim Sabouri
- Department of Medical Biochemistry and Biophysics, Umeå University, 901 87, Umeå, Sweden.
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Abstract
In-cell structural biology aims at extracting structural information about proteins or nucleic acids in their native, cellular environment. This emerging field holds great promise and is already providing new facts and outlooks of interest at both fundamental and applied levels. NMR spectroscopy has important contributions on this stage: It brings information on a broad variety of nuclei at the atomic scale, which ensures its great versatility and uniqueness. Here, we detail the methods, the fundamental knowledge, and the applications in biomedical engineering related to in-cell structural biology by NMR. We finally propose a brief overview of the main other techniques in the field (EPR, smFRET, cryo-ET, etc.) to draw some advisable developments for in-cell NMR. In the era of large-scale screenings and deep learning, both accurate and qualitative experimental evidence are as essential as ever to understand the interior life of cells. In-cell structural biology by NMR spectroscopy can generate such a knowledge, and it does so at the atomic scale. This review is meant to deliver comprehensive but accessible information, with advanced technical details and reflections on the methods, the nature of the results, and the future of the field.
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Affiliation(s)
- Francois-Xavier Theillet
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
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Development of a Smart Fluorescent Probe Specifically Interacting with C-Myc I-Motif. Int J Mol Sci 2022; 23:ijms23073872. [PMID: 35409230 PMCID: PMC8998492 DOI: 10.3390/ijms23073872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 03/27/2022] [Accepted: 03/28/2022] [Indexed: 11/17/2022] Open
Abstract
I-motifs play key regulatory roles in biological processes, holding great potential as attractive therapeutic targets. In the present study, we developed a novel fluorescent probe G59 with strong and selective binding to the c-myc gene promoter i-motif. G59 had an i-motif-binding carbazole moiety conjugated with naphthalimide fluorescent groups. G59 could differentiate the c-myc i-motif from other DNA structures through selective activation of its fluorescence, with its apparent visualization in solution. The smart probe G59 showed excellent sensitivity, with a low fluorescent detection limit of 154 nM and effective stabilization to the c-myc i-motif. G59 could serve as a rapid and sensitive probe for label-free screening of selective c-myc i-motif binding ligands under neutral crowding conditions. To the best of our knowledge, G59 is the first fluorescent probe with high sensitivity for recognizing the i-motif structure and screening for selective binding ligands.
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Amato J, Iaccarino N, D'Aria F, D'Amico F, Randazzo A, Giancola C, Cesàro A, Di Fonzo S, Pagano B. Conformational plasticity of DNA secondary structures: probing the conversion between i-motif and hairpin species by circular dichroism and ultraviolet resonance Raman spectroscopies. Phys Chem Chem Phys 2022; 24:7028-7044. [PMID: 35258065 DOI: 10.1039/d2cp00058j] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The promoter regions of important oncogenes such as BCL2 and KRAS contain GC-rich sequences that can form distinctive noncanonical DNA structures involved in the regulation of transcription: G-quadruplexes on the G-rich strand and i-motifs on the C-rich strand. Interestingly, BCL2 and KRAS promoter i-motifs are highly dynamic in nature and exist in a pH-dependent equilibrium with hairpin and even with hybrid i-motif/hairpin species. Herein, the effects of pH and presence of cell-mimicking molecular crowding conditions on conformational equilibria of the BCL2 and KRAS i-motif-forming sequences were investigated by ultraviolet resonance Raman (UVRR) and circular dichroism (CD) spectroscopies. Multivariate analysis of CD data was essential to model the presence and identity of the species involved. Analysis of UVRR spectra measured as a function of pH, performed also by the two-dimensional correlation spectroscopy (2D-COS) technique, showed the role of several functional groups in the DNA conformational transitions, and provided structural and dynamic information. Thus, the UVRR investigation of intramolecular interactions and of local and environmental dynamics in promoting the different species induced by the solution conditions provided valuable insights into i-motif conformational transitions. The combined use of the two spectroscopic tools is emphasized by the relevant possibility of working in the same DNA concentration range and by the heterospectral UVRR/CD 2D-COS analysis. The results of this study shed light on the factors that can influence at the molecular level the equilibrium between the different conformational species putatively involved in the oncogene expression.
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Affiliation(s)
- Jussara Amato
- Department of Pharmacy, University of Naples Federico II, Naples, I-80131, Italy.
| | - Nunzia Iaccarino
- Department of Pharmacy, University of Naples Federico II, Naples, I-80131, Italy.
| | - Federica D'Aria
- Department of Pharmacy, University of Naples Federico II, Naples, I-80131, Italy.
| | - Francesco D'Amico
- Elettra-Sincrotrone Trieste S. C. p. A., Science Park, Trieste, I-34149, Italy.
| | - Antonio Randazzo
- Department of Pharmacy, University of Naples Federico II, Naples, I-80131, Italy.
| | - Concetta Giancola
- Department of Pharmacy, University of Naples Federico II, Naples, I-80131, Italy.
| | - Attilio Cesàro
- Elettra-Sincrotrone Trieste S. C. p. A., Science Park, Trieste, I-34149, Italy.
| | - Silvia Di Fonzo
- Elettra-Sincrotrone Trieste S. C. p. A., Science Park, Trieste, I-34149, Italy.
| | - Bruno Pagano
- Department of Pharmacy, University of Naples Federico II, Naples, I-80131, Italy.
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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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46
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Mendes E, Aljnadi IM, Bahls B, Victor BL, Paulo A. Major Achievements in the Design of Quadruplex-Interactive Small Molecules. Pharmaceuticals (Basel) 2022; 15:ph15030300. [PMID: 35337098 PMCID: PMC8953082 DOI: 10.3390/ph15030300] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 02/22/2022] [Accepted: 02/24/2022] [Indexed: 12/17/2022] Open
Abstract
Organic small molecules that can recognize and bind to G-quadruplex and i-Motif nucleic acids have great potential as selective drugs or as tools in drug target discovery programs, or even in the development of nanodevices for medical diagnosis. Hundreds of quadruplex-interactive small molecules have been reported, and the challenges in their design vary with the intended application. Herein, we survey the major achievements on the therapeutic potential of such quadruplex ligands, their mode of binding, effects upon interaction with quadruplexes, and consider the opportunities and challenges for their exploitation in drug discovery.
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Affiliation(s)
- Eduarda Mendes
- Faculty of Pharmacy, Research Institute for Medicines (iMed.Ulisboa), Universidade de Lisboa, 1649-003 Lisbon, Portugal; (E.M.); (I.M.A.); (B.B.)
| | - Israa M. Aljnadi
- Faculty of Pharmacy, Research Institute for Medicines (iMed.Ulisboa), Universidade de Lisboa, 1649-003 Lisbon, Portugal; (E.M.); (I.M.A.); (B.B.)
- Faculty of Sciences, BioISI, Biosystems and Integrative Sciences Institute, Universidade de Lisboa, 1749-016 Lisbon, Portugal;
| | - Bárbara Bahls
- Faculty of Pharmacy, Research Institute for Medicines (iMed.Ulisboa), Universidade de Lisboa, 1649-003 Lisbon, Portugal; (E.M.); (I.M.A.); (B.B.)
- Faculty of Sciences, BioISI, Biosystems and Integrative Sciences Institute, Universidade de Lisboa, 1749-016 Lisbon, Portugal;
| | - Bruno L. Victor
- Faculty of Sciences, BioISI, Biosystems and Integrative Sciences Institute, Universidade de Lisboa, 1749-016 Lisbon, Portugal;
| | - Alexandra Paulo
- Faculty of Pharmacy, Research Institute for Medicines (iMed.Ulisboa), Universidade de Lisboa, 1649-003 Lisbon, Portugal; (E.M.); (I.M.A.); (B.B.)
- Correspondence:
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47
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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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48
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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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49
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Luteran EM, Paukstelis PJ. The parallel-stranded d(CGA) duplex is a highly predictable structural motif with two conformationally distinct strands. Acta Crystallogr D Struct Biol 2022; 78:299-309. [PMID: 35234144 PMCID: PMC8900823 DOI: 10.1107/s2059798322000304] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 01/10/2022] [Indexed: 11/10/2022] Open
Abstract
DNA can adopt noncanonical structures that have important biological functions while also providing structural diversity for applications in nanotechnology. Here, the crystal structures of two oligonucleotides composed of d(CGA) triplet repeats in the parallel-stranded duplex form are described. The structure determination of four unique d(CGA)-based parallel-stranded duplexes across two crystal structures has allowed the structural parameters of d(CGA) triplets in the parallel-stranded duplex form to be characterized and established. These results show that d(CGA) units are highly uniform, but that each strand in the duplex is structurally unique and has a distinct role in accommodating structural asymmetries induced by the C-CH+ base pair.
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Affiliation(s)
- Emily M. Luteran
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA
| | - Paul J. Paukstelis
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA,Correspondence e-mail:
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50
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Gao B, Zheng YT, Su AM, Sun B, Xi XG, Hou XM. Remodeling the conformational dynamics of I-motif DNA by helicases in ATP-independent mode at acidic environment. iScience 2022; 25:103575. [PMID: 34988409 PMCID: PMC8704484 DOI: 10.1016/j.isci.2021.103575] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 10/09/2021] [Accepted: 12/03/2021] [Indexed: 01/18/2023] Open
Abstract
I-motifs are noncanonical four-stranded DNA structures formed by C-rich sequences at acidic environment with critical biofunctions. The particular pH sensitivity has inspired the development of i-motifs as pH sensors and DNA motors in nanotechnology. However, the folding and regulation mechanisms of i-motifs remain elusive. Here, using single-molecule FRET, we first show that i-motifs are more dynamic than G4s. Impressively, i-motifs display a high diversity of six folding species with slow interconversion. Further results indicate that i-motifs can be linearized by Replication protein A. More importantly, we identified a number of helicases with high specificity to i-motifs at low pH. All these helicases directly act on and efficiently resolve i-motifs into intermediates independent of ATP, although they poorly unwind G4 or duplex at low pH. Owing to the extreme sensitivity to helicases and no need for ATP, i-motif may be applied as a probe for helicase sensing both in vitro and in vivo.
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Affiliation(s)
- Bo Gao
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling 712100, China
| | - Ya-Ting Zheng
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling 712100, China
| | - Ai-Min Su
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling 712100, China
| | - Bo Sun
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Xu-Guang Xi
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling 712100, China
- LBPA, Ecole Normale Supérieure Paris-Saclay, CNRS, Gif-sur-Yvette, France
| | - Xi-Miao Hou
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling 712100, China
- Corresponding author
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