1
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Benigno D, Navarro N, Aviñó A, Esposito V, Galeone A, Virgilio A, Fàbrega C, Eritja R. Aptamer-Drug conjugates for a targeted and synergistic anticancer Response: Exploiting T30923-5-fluoro-2'-deoxyuridine (INT-FdU) derivatives. Eur J Pharm Biopharm 2024; 201:114354. [PMID: 38852755 DOI: 10.1016/j.ejpb.2024.114354] [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: 03/26/2024] [Revised: 05/29/2024] [Accepted: 06/07/2024] [Indexed: 06/11/2024]
Abstract
One of the most appealing approaches for cancer treatment is targeted therapy, which is based on the use of drugs able to target cancer cells without affecting normal ones. This strategy lets to overcome the major limitation of conventional chemotherapy, namely the lack of specificity of anticancer drugs, which often leads to severe side effects, decreasing the therapy effectiveness. Delivery of cell-killing substances to tumor cells is one-way targeted drug therapy can work. Generally, monoclonal antibodies are combined with chemotherapeutic drugs, allowing cellular uptake through the binding to their targets on the surface of cancer cells. Aptamer-drug conjugates represent a promising alternative solution to antibodies to minimize off-target effects, considering the remarkable selective binding capabilities of aptamers. In this study, to enhance the therapeutic efficacy of the antineoplastic agent 5-fluoro-2'-deoxyuridine (FdU) in various cancer cells, we focused on the development of a novel conjugate using the antiproliferative aptamer T30923 (INT) as a drug vehicle. Three derivatives composed of T30923 conjugated with a different number of FdU units were synthesized, and their structural and biological properties were thoroughly characterized, highlighting their potential for targeted and synergistic anticancer responses.
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Affiliation(s)
- Daniela Benigno
- Department of Pharmacy, University of Naples Federico II, Napoli 80131, Italy
| | - Natalia Navarro
- Nucleic Acids Chemistry Group, Institute for Advanced Chemistry of Catalonia (IQAC-CSIC), Barcelona 08034, Spain; Nucleic Acids Chemistry Group, Networking Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona 08034, Spain
| | - Anna Aviñó
- Nucleic Acids Chemistry Group, Institute for Advanced Chemistry of Catalonia (IQAC-CSIC), Barcelona 08034, Spain; Nucleic Acids Chemistry Group, Networking Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona 08034, Spain
| | - Veronica Esposito
- Department of Pharmacy, University of Naples Federico II, Napoli 80131, Italy
| | - Aldo Galeone
- Department of Pharmacy, University of Naples Federico II, Napoli 80131, Italy
| | - Antonella Virgilio
- Department of Pharmacy, University of Naples Federico II, Napoli 80131, Italy.
| | - Carme Fàbrega
- Nucleic Acids Chemistry Group, Institute for Advanced Chemistry of Catalonia (IQAC-CSIC), Barcelona 08034, Spain; Nucleic Acids Chemistry Group, Networking Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona 08034, Spain.
| | - Ramon Eritja
- Nucleic Acids Chemistry Group, Institute for Advanced Chemistry of Catalonia (IQAC-CSIC), Barcelona 08034, Spain; Nucleic Acids Chemistry Group, Networking Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona 08034, Spain.
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2
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Tevonyan LL, Bazhulina NP, Kaluzhny DN. Enhancement of intrinsic guanine fluorescence by protonation in DNA of various structures. Biochimie 2024; 222:101-108. [PMID: 38447859 DOI: 10.1016/j.biochi.2024.03.003] [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: 12/07/2023] [Revised: 02/24/2024] [Accepted: 03/03/2024] [Indexed: 03/08/2024]
Abstract
Understanding the diversity of DNA structure and functions in biology requires tools to study this biomolecule selectively and thoroughly. Fluorescence methods are powerful technique for non-invasive research. Due to the low quantum yield, the intrinsic fluorescence of nucleotides has not been considered for use in the detection and differentiation of nucleic acid bases. Here, we have studied the influence of protonation of nucleotides on their fluorescence properties. We show that protonation of ATP and GTP leads to enhanced intrinsic fluorescence. Fluorescence enhancement at acidic pH has been observed for double-stranded DNA and single-stranded oligonucleotides. The formation of G4 secondary structures apparently protected certain nucleotides from protonation, resulting in less pronounced fluorescence enhancement. Furthermore, acid-induced depurination under protonation was less noticeable in G4 structures than in double-stranded and single-stranded DNA. We show that changes in the intrinsic fluorescence of guanine can be used as a sensitive sensor for changes in the structure of the DNA and for the protonation of specific nucleotides.
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Affiliation(s)
- Liana L Tevonyan
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 32 Vavilov st., 119991, Moscow, Russia; Moscow Institute of Physics and Technology (National Research University), 9 Institutskiy per., Dolgoprudny, 141701, Moscow Region, Russia
| | - Natalia P Bazhulina
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 32 Vavilov st., 119991, Moscow, Russia
| | - Dmitry N Kaluzhny
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 32 Vavilov st., 119991, Moscow, Russia.
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3
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Tevonyan LL, Beniaminov AD, Kaluzhny DN. Quenching of G4-DNA intrinsic fluorescence by ligands. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2024; 53:47-56. [PMID: 38217705 DOI: 10.1007/s00249-023-01696-3] [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: 06/30/2023] [Revised: 11/10/2023] [Accepted: 12/11/2023] [Indexed: 01/15/2024]
Abstract
G-quadruplex (G4) structures formed by the guanine-rich DNA regions exhibit several distinctive optical properties, including UV absorption and circular dichroism spectra. Some G4 DNA possess intrinsic UV fluorescence whose origin is not completely clear to date. In this work, we study the effect of TMPyP4 and Methylene Blue on the intrinsic fluorescence of the dimeric G4 DNA structure formed by two d(G3T)4 sequences. We demonstrate that binding of the ligands results in quenching of the intrinsic fluorescence, although the conformation of the G4 DNA and its dimeric structure remain preserved. The binding sites of the ligands were suggested by the photoinduced oxidation of guanines and analysis of binding isoterms. We discuss how DNA-ligand complexes can affect the intrinsic fluorescence of G4 DNA.
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Affiliation(s)
- Liana L Tevonyan
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991, Moscow, Russia
| | - Artemy D Beniaminov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991, Moscow, Russia
| | - Dmitry N Kaluzhny
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991, Moscow, Russia.
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4
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Banerjee A, Anand M, Kalita S, Ganji M. Single-molecule analysis of DNA base-stacking energetics using patterned DNA nanostructures. NATURE NANOTECHNOLOGY 2023; 18:1474-1482. [PMID: 37591937 PMCID: PMC10716042 DOI: 10.1038/s41565-023-01485-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 07/10/2023] [Indexed: 08/19/2023]
Abstract
The DNA double helix structure is stabilized by base-pairing and base-stacking interactions. However, a comprehensive understanding of dinucleotide base-stacking energetics is lacking. Here we combined multiplexed DNA-based point accumulation in nanoscale topography (DNA-PAINT) imaging with designer DNA nanostructures and measured the free energy of dinucleotide base stacking at the single-molecule level. Multiplexed imaging enabled us to extract the binding kinetics of an imager strand with and without additional dinucleotide stacking interactions. The DNA-PAINT data showed that a single additional dinucleotide base stacking results in up to 250-fold stabilization for the DNA duplex nanostructure. We found that the dinucleotide base-stacking energies vary from -0.95 ± 0.12 kcal mol-1 to -3.22 ± 0.04 kcal mol-1 for C|T and A|C base-stackings, respectively. We demonstrate the application of base-stacking energetics in designing DNA-PAINT probes for multiplexed super-resolution imaging, and efficient assembly of higher-order DNA nanostructures. Our results will aid in designing functional DNA nanostructures, and DNA and RNA aptamers, and facilitate better predictions of the local DNA structure.
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Affiliation(s)
- Abhinav Banerjee
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Micky Anand
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Simanta Kalita
- New Chemistry Unit and Chemistry and Physics of Materials Unit, The Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, India
| | - Mahipal Ganji
- Department of Biochemistry, Indian Institute of Science, Bangalore, India.
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5
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Roxo C, Zielińska K, Pasternak A. Bispecific G-quadruplexes as inhibitors of cancer cells growth. Biochimie 2023; 214:91-100. [PMID: 37562706 DOI: 10.1016/j.biochi.2023.08.008] [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: 06/16/2023] [Revised: 08/01/2023] [Accepted: 08/07/2023] [Indexed: 08/12/2023]
Abstract
A therapeutic system with the ability to target more than one protein is an important aim of cancer therapy since tumor growth is accompanied by dysregulation of many biological pathways. G-quadruplexes (G4s) are non-canonical structures formed by guanine-rich DNA or RNA oligonucleotides, with the ability to bind to different targets. In this study, we constructed ten novel bispecific G-quadruplex conjugates based on AT11, TBA, T40214 and T40231 aptamer structures, with the ability to bind two different targets at once in cancer cells. We analyzed the physicochemical aspects and the anticancer properties of novel molecules relating them with the single G-quadruplex unit and attempted to comprehend the correlation between the structures of bispecific G-quadruplexes with their biological activity. Our studies uncovered conjugates with considerable antiproliferative potential in HeLa and MCF-7 cancer cell lines, however with relatively low thermal stability or low nuclease resistance. Three conjugates among all studied oligonucleotides possess improved antiproliferative activity in MCF-7 cell line in comparison to their single G-quadruplex units leading to up to 90% inhibition of cancer cells growth, but their inhibitory potential is rather comparable to the effect observed for mix of two separate G-quadruplex units. Importantly, the conjugation enhances oligonucleotides enzymatic stability leading to the improvement of their therapeutic profile. The comprehensive studies presented herein indicate new approach for possibly effective cancer therapy and for the design of G4-based drugs.
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Affiliation(s)
- Carolina Roxo
- Department of Nucleic Acids Bioengineering, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704, Poznan, Poland
| | - Karolina Zielińska
- Department of Biomolecular NMR, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704, Poznan, Poland
| | - Anna Pasternak
- Department of Nucleic Acids Bioengineering, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704, Poznan, Poland.
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6
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Kundu N, Sharma T, Kaur S, Mahto AK, Prasad Dewangan R, Shankaraswamy J, Saxena S. Significant destabilization of human telomeric G-quadruplex upon peptide binding: dramatic effect of flanking bases. J Biomol Struct Dyn 2023; 41:7119-7127. [PMID: 36038986 DOI: 10.1080/07391102.2022.2116602] [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: 07/03/2022] [Accepted: 08/16/2022] [Indexed: 10/14/2022]
Abstract
Human telomere is composed of highly repeated hexanucleotide sequence TTAGGG and a 3' single-stranded DNA tail. Many telomere G4 topologies characterized at atomic level by X-ray crystallography and NMR studies. Until now, various small ligands developed to interact with G-quadruplex mainly to stabilize the structure and least is known for its destabilization. In this study, we provide the first evidence of human telomeric G4 destabilization upon peptide binding in dilute and cell-mimicking molecular crowing conditions due to the changes in flanking bases of human telomeric sequences. Hence, our findings will open the new ways to target diseases related with increasing the efficiency of DNA replication, transcription or duplex reannealing.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Nikita Kundu
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Noida, India
| | - Taniya Sharma
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Noida, India
| | - Sarvpreet Kaur
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Noida, India
| | - Aman Kumar Mahto
- Department of Pharmaceutical Chemistry, School of Pharmaceutical Education and Research, Jamia Hamdard, New Delhi, India
| | - Rikeshwer Prasad Dewangan
- Department of Pharmaceutical Chemistry, School of Pharmaceutical Education and Research, Jamia Hamdard, New Delhi, India
| | - J Shankaraswamy
- Department of Fruit Science, College of Horticulture, Mojerla, Sri Konda Laxman Telangana State Horticultural University, Hyderabad, India
| | - Sarika Saxena
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Noida, India
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7
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De Piante E, D'Aria F, Napolitano LMR, Amato J, Pirrello S, Onesti S, Giancola C. Exploring the G-quadruplex binding and unwinding activity of the bacterial FeS helicase DinG. Sci Rep 2023; 13:12610. [PMID: 37537265 PMCID: PMC10400533 DOI: 10.1038/s41598-023-39675-5] [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: 04/26/2023] [Accepted: 07/28/2023] [Indexed: 08/05/2023] Open
Abstract
Despite numerous reports on the interactions of G-quadruplexes (G4s) with helicases, systematic analysis addressing the selectivity and specificity of each helicase towards a variety of G4 topologies are scarce. Among the helicases able to unwind G4s are those containing an iron-sulphur (FeS) cluster, including both the bacterial DinG (found in E. coli and several pathogenic bacteria) and the medically important eukaryotic homologues (XPD, FancJ, DDX11 and RTEL1). We carried out a detailed study of the interactions between the E. coli DinG and a variety of G4s, by employing physicochemical and biochemical methodologies. A series of G4-rich sequences from different genomic locations (promoter and telomeric regions), able to form unimolecular G4 structures with diverse topologies, were analyzed (c-KIT1, KRAS, c-MYC, BCL2, Tel23, T30695, Zic1). DinG binds to most of the investigated G4s with little discrimination, while it exhibits a clear degree of unwinding specificity towards different G4 topologies. Whereas previous reports suggested that DinG was active only on bimolecular G4s, here we show that it is also able to bind to and resolve the more physiologically relevant unimolecular G4s. In addition, when the G4 structures were stabilized by ligands (Pyridostatin, PhenDC3, BRACO-19 or Netropsin), the DinG unwinding activity decreased and in most cases was abolished, with a pattern that is not simply explained by a change in binding affinity. Overall, these results have important implications for the biochemistry of helicases, strongly suggesting that when analysing the G4 unwinding property of an enzyme, it is necessary to investigate a variety of G4 substrates.
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Affiliation(s)
- Elisa De Piante
- Structural Biology Laboratory, Elettra-Sincrotrone Trieste S.C.p.A, 34149, Trieste, Italy
- Department of Pharmacy, University of Naples Federico II, 80131, Naples, Italy
| | - Federica D'Aria
- Department of Pharmacy, University of Naples Federico II, 80131, Naples, Italy
| | - Luisa M R Napolitano
- Structural Biology Laboratory, Elettra-Sincrotrone Trieste S.C.p.A, 34149, Trieste, Italy
| | - Jussara Amato
- Department of Pharmacy, University of Naples Federico II, 80131, Naples, Italy
| | - Simone Pirrello
- Structural Biology Laboratory, Elettra-Sincrotrone Trieste S.C.p.A, 34149, Trieste, Italy
| | - Silvia Onesti
- Structural Biology Laboratory, Elettra-Sincrotrone Trieste S.C.p.A, 34149, Trieste, Italy.
| | - Concetta Giancola
- Department of Pharmacy, University of Naples Federico II, 80131, Naples, Italy.
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8
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Esposito V, Benigno D, Bello I, Panza E, Bucci M, Virgilio A, Galeone A. Structural and Biological Features of G-Quadruplex Aptamers as Promising Inhibitors of the STAT3 Signaling Pathway. Int J Mol Sci 2023; 24:ijms24119524. [PMID: 37298475 DOI: 10.3390/ijms24119524] [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: 05/10/2023] [Revised: 05/25/2023] [Accepted: 05/26/2023] [Indexed: 06/12/2023] Open
Abstract
In this paper, we investigate the structural and biological features of G-quadruplex (G4) aptamers as promising antiproliferative compounds affecting the STAT3 signalling pathway. Targeting the STAT3 protein through high-affinity ligands to reduce its levels or activity in cancer has noteworthy therapeutic potential. T40214 (STAT) [(G3C)4] is a G4 aptamer that can influence STAT3 biological outcomes in an efficient manner in several cancer cells. To explore the effects of an extra cytidine in second position and/or of single site-specific replacements of loop residues in generating aptamers that can affect the STAT3 biochemical pathway, a series of STAT and STATB [GCG2(CG3)3C] analogues containing a thymidine residue instead of cytidines was prepared. NMR, CD, UV, and PAGE data suggested that all derivatives adopt dimeric G4 structures like that of unmodified T40214 endowed with higher thermal stability, keeping the resistance in biological environments substantially unchanged, as shown by the nuclease stability assay. The antiproliferative activity of these ODNs was tested on both human prostate (DU145) and breast (MDA-MB-231) cancer cells. All derivatives showed similar antiproliferative activities on both cell lines, revealing a marked inhibition of proliferation, particularly at 72 h at 30 µM. Transcriptomic analysis aimed to evaluate STAT's and STATB's influence on the expression of many genes in MDA-MB-231 cells, suggested their potential involvement in STAT3 pathway modulation, and thus their interference in different biological processes. These data provide new tools to affect an interesting biochemical pathway and to develop novel anticancer and anti-inflammatory drugs.
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Affiliation(s)
- Veronica Esposito
- Department of Pharmacy, University of Naples Federico II, Via D. Montesano 49, I-80131 Naples, Italy
| | - Daniela Benigno
- Department of Pharmacy, University of Naples Federico II, Via D. Montesano 49, I-80131 Naples, Italy
| | - Ivana Bello
- Department of Pharmacy, University of Naples Federico II, Via D. Montesano 49, I-80131 Naples, Italy
| | - Elisabetta Panza
- Department of Pharmacy, University of Naples Federico II, Via D. Montesano 49, I-80131 Naples, Italy
| | - Mariarosaria Bucci
- Department of Pharmacy, University of Naples Federico II, Via D. Montesano 49, I-80131 Naples, Italy
| | - Antonella Virgilio
- Department of Pharmacy, University of Naples Federico II, Via D. Montesano 49, I-80131 Naples, Italy
| | - Aldo Galeone
- Department of Pharmacy, University of Naples Federico II, Via D. Montesano 49, I-80131 Naples, Italy
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9
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Ishiguro A, Ishihama A. ALS-linked TDP-43 mutations interfere with the recruitment of RNA recognition motifs to G-quadruplex RNA. Sci Rep 2023; 13:5982. [PMID: 37046025 PMCID: PMC10097714 DOI: 10.1038/s41598-023-33172-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 04/08/2023] [Indexed: 04/14/2023] Open
Abstract
TDP-43 is a major pathological protein in sporadic and familial amyotrophic lateral sclerosis (ALS) and mediates mRNA fate. TDP-43 dysfunction leads to causes progressive degeneration of motor neurons, the details of which remain elusive. Elucidation of the molecular mechanisms of RNA binding could enhance our understanding of this devastating disease. We observed the involvement of the glycine-rich (GR) region of TDP-43 in the initial recognition and binding of G-quadruplex (G4)-RNA in conjunction with its RNA recognition motifs (RRM). We performed a molecular dissection of these intramolecular RNA-binding modules in this study. We confirmed that the ALS-linked mutations in the GR region lead to alteration in the G4 structure. In contrast, amino acid substitutions in the GR region alter the protein structure but do not void the interaction with G4-RNA. Based on these observations, we concluded that the structural distortion of G4 caused by these mutations interferes with RRM recruitment and leads to TDP-43 dysfunction. This intramolecular organization between RRM and GR regions modulates the overall G4-binding properties.
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Affiliation(s)
- Akira Ishiguro
- Research Center for Micro-Nano Technology, Hosei University, Midori-cho 3-11-15, Koganei, Tokyo, 184-0003, Japan.
| | - Akira Ishihama
- Research Center for Micro-Nano Technology, Hosei University, Midori-cho 3-11-15, Koganei, Tokyo, 184-0003, Japan
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10
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Monsen RC, Chua ED, Hopkins J, Chaires J, Trent J. Structure of a 28.5 kDa duplex-embedded G-quadruplex system resolved to 7.4 Å resolution with cryo-EM. Nucleic Acids Res 2023; 51:1943-1959. [PMID: 36715343 PMCID: PMC9976903 DOI: 10.1093/nar/gkad014] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 12/16/2022] [Accepted: 01/04/2023] [Indexed: 01/31/2023] Open
Abstract
Genomic regions with high guanine content can fold into non-B form DNA four-stranded structures known as G-quadruplexes (G4s). Extensive in vivo investigations have revealed that promoter G4s are transcriptional regulators. Little structural information exists for these G4s embedded within duplexes, their presumed genomic environment. Here, we report the 7.4 Å resolution structure and dynamics of a 28.5 kDa duplex-G4-duplex (DGD) model system using cryo-EM, molecular dynamics, and small-angle X-ray scattering (SAXS) studies. The DGD cryo-EM refined model features a 53° bend induced by a stacked duplex-G4 interaction at the 5' G-tetrad interface with a persistently unstacked 3' duplex. The surrogate complement poly dT loop preferably stacks onto the 3' G-tetrad interface resulting in occlusion of both 5' and 3' tetrad interfaces. Structural analysis shows that the DGD model is quantifiably more druggable than the monomeric G4 structure alone and represents a new structural drug target. Our results illustrate how the integration of cryo-EM, MD, and SAXS can reveal complementary detailed static and dynamic structural information on DNA G4 systems.
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Affiliation(s)
- Robert C Monsen
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - Eugene Y D Chua
- National Center for CryoEM Access and Training (NCCAT), Simons Electron Microscopy Center, New York Structural Biology Center, NY 10027, USA
| | - Jesse B Hopkins
- The Biophysics Collaborative Access Team (BioCAT), Department of Biological, Chemical, and Physical Sciences, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Jonathan B Chaires
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
- Department of Medicine, University of Louisville, Louisville, KY 40202, USA
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY 40202, USA
| | - John O Trent
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
- Department of Medicine, University of Louisville, Louisville, KY 40202, USA
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY 40202, USA
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11
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Cao Y, Li W, Pei R. Exploring the catalytic mechanism of multivalent G-quadruplex/hemin DNAzymes by modulating the position and spatial orientation of connected G-quadruplexes. Anal Chim Acta 2022; 1221:340105. [DOI: 10.1016/j.aca.2022.340105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 06/06/2022] [Accepted: 06/18/2022] [Indexed: 11/15/2022]
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12
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Mellor C, Perez C, Sale JE. Creation and resolution of non-B-DNA structural impediments during replication. Crit Rev Biochem Mol Biol 2022; 57:412-442. [PMID: 36170051 PMCID: PMC7613824 DOI: 10.1080/10409238.2022.2121803] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Revised: 08/02/2022] [Accepted: 08/25/2022] [Indexed: 01/27/2023]
Abstract
During replication, folding of the DNA template into non-B-form secondary structures provides one of the most abundant impediments to the smooth progression of the replisome. The core replisome collaborates with multiple accessory factors to ensure timely and accurate duplication of the genome and epigenome. Here, we discuss the forces that drive non-B structure formation and the evidence that secondary structures are a significant and frequent source of replication stress that must be actively countered. Taking advantage of recent advances in the molecular and structural biology of the yeast and human replisomes, we examine how structures form and how they may be sensed and resolved during replication.
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Affiliation(s)
- Christopher Mellor
- Division of Protein & Nucleic Acid Chemistry, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Consuelo Perez
- Division of Protein & Nucleic Acid Chemistry, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Julian E Sale
- Division of Protein & Nucleic Acid Chemistry, MRC Laboratory of Molecular Biology, Cambridge, UK
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13
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Monsen RC, Maguire JM, DeLeeuw LW, Chaires JB, Trent JO. Drug discovery of small molecules targeting the higher-order hTERT promoter G-quadruplex. PLoS One 2022; 17:e0270165. [PMID: 35709230 PMCID: PMC9202945 DOI: 10.1371/journal.pone.0270165] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 06/03/2022] [Indexed: 12/15/2022] Open
Abstract
DNA G-quadruplexes (G4s) are now widely accepted as viable targets in the pursuit of anticancer therapeutics. To date, few small molecules have been identified that exhibit selectivity for G4s over alternative forms of DNA, such as the ubiquitous duplex. We posit that the lack of current ligand specificity arises for multiple reasons: G4 atomic models are often small, monomeric, single quadruplex structures with few or no druggable pockets; targeting G-tetrad faces frequently results in the enrichment of extended electron-deficient polyaromatic end-pasting scaffolds; and virtual drug discovery efforts often under-sample chemical search space. We show that by addressing these issues we can enrich for non-standard molecular templates that exhibit high selectivity towards G4s over other forms of DNA. We performed an extensive virtual screen against the higher-order hTERT core promoter G4 that we have previously characterized, targeting 12 of its unique loop and groove pockets using libraries containing 40 million drug-like compounds for each screen. Using our drug discovery funnel approach, which utilizes high-throughput fluorescence thermal shift assay (FTSA) screens, microscale thermophoresis (MST), and orthogonal biophysical methods, we have identified multiple unique G4 binding scaffolds. We subsequently used two rounds of catalogue-based SAR to increase the affinity of a disubstituted 2-aminoethyl-quinazoline that stabilizes the higher-order hTERT G-quadruplex by binding across its G4 junctional sites. We show selectivity of its binding affinity towards hTERT is virtually unaffected in the presence of near-physiological levels of duplex DNA, and that this molecule downregulates hTERT transcription in breast cancer cells.
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Affiliation(s)
- Robert C. Monsen
- UofL Health Brown Cancer Center, University of Louisville, Louisville, Kentucky, United States of America
| | - Jon M. Maguire
- UofL Health Brown Cancer Center, University of Louisville, Louisville, Kentucky, United States of America
| | - Lynn W. DeLeeuw
- UofL Health Brown Cancer Center, University of Louisville, Louisville, Kentucky, United States of America
| | - Jonathan B. Chaires
- UofL Health Brown Cancer Center, University of Louisville, Louisville, Kentucky, United States of America
- Department of Medicine, University of Louisville, Louisville, Kentucky, United States of America
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, Kentucky, United States of America
- * E-mail: (JBC); (JOT)
| | - John O. Trent
- UofL Health Brown Cancer Center, University of Louisville, Louisville, Kentucky, United States of America
- Department of Medicine, University of Louisville, Louisville, Kentucky, United States of America
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, Kentucky, United States of America
- * E-mail: (JBC); (JOT)
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14
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Virgilio A, Pecoraro A, Benigno D, Russo A, Russo G, Esposito V, Galeone A. Antiproliferative Effects of the Aptamer d(GGGT) 4 and Its Analogues with an Abasic-Site Mimic Loop on Different Cancer Cells. Int J Mol Sci 2022; 23:ijms23115952. [PMID: 35682635 PMCID: PMC9181107 DOI: 10.3390/ijms23115952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 05/20/2022] [Accepted: 05/24/2022] [Indexed: 11/24/2022] Open
Abstract
In this paper, we study the T30923 antiproliferative potential and the contribution of its loop residues in six different human cancer cell lines by preparing five T30923 variants using the single residue replacement approach of loop thymidine with an abasic site mimic (S). G-rich oligonucleotides (GRO) show interesting anticancer properties because of their capability to adopt G-quadruplex structures (G4s), such as the G4 HIV-1 integrase inhibitor T30923. Considering the multi-targeted effects of G4-aptamers and the limited number of cancer cell lines tested, particularly for T30923, it should be important to find a suitable tumor line, in addition to considering that the effects also strictly depend on G4s. CD, NMR and non-denaturating polyacrylamide gel electrophoresis data clearly show that all modified ODNs closely resemble the dimeric structure of parallel G4s’ parent aptamer, keeping the resistance in biological environments substantially unchanged, as shown by nuclease stability assay. The antiproliferative effects of T30923 and its variants are tried in vitro by MTT assays, showing interesting cytotoxic activity, depending on time and dose, for all G4s, especially in MDA-MB-231 cells with a reduction in cell viability approximately up to 30%. Among all derivatives, QS12 results are the most promising, showing more pronounced cytotoxic effects both in MDA-MB-231 and Hela cells, with a decrease in cell viability from 70% to 60%. In summary, the single loop residue S substitution approach may be useful for designing antiproliferative G4s, considering that most of them, characterized by single residue loops, may be able to bind different targets in several cancer cell pathways. Generally, this approach could be of benefit by revealing some minimal functional structures, stimulating further studies aimed at the development of novel anticancer drugs.
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15
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Monsen RC, DeLeeuw LW, Dean W, Gray R, Chakravarthy S, Hopkins J, Chaires J, Trent J. Long promoter sequences form higher-order G-quadruplexes: an integrative structural biology study of c-Myc, k-Ras and c-Kit promoter sequences. Nucleic Acids Res 2022; 50:4127-4147. [PMID: 35325198 PMCID: PMC9023277 DOI: 10.1093/nar/gkac182] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 03/03/2022] [Accepted: 03/21/2022] [Indexed: 12/15/2022] Open
Abstract
We report on higher-order G-quadruplex structures adopted by long promoter sequences obtained by an iterative integrated structural biology approach. Our approach uses quantitative biophysical tools (analytical ultracentrifugation, small-angle X-ray scattering, and circular dichroism spectroscopy) combined with modeling and molecular dynamics simulations, to derive self-consistent structural models. The formal resolution of our approach is 18 angstroms, but in some cases structural features of only a few nucleotides can be discerned. We report here five structures of long (34-70 nt) wild-type sequences selected from three cancer-related promoters: c-Myc, c-Kit and k-Ras. Each sequence studied has a unique structure. Three sequences form structures with two contiguous, stacked, G-quadruplex units. One longer sequence from c-Myc forms a structure with three contiguous stacked quadruplexes. A longer c-Kit sequence forms a quadruplex-hairpin structure. Each structure exhibits interfacial regions between stacked quadruplexes or novel loop geometries that are possible druggable targets. We also report methodological advances in our integrated structural biology approach, which now includes quantitative CD for counting stacked G-tetrads, DNaseI cleavage for hairpin detection and SAXS model refinement. Our results suggest that higher-order quadruplex assemblies may be a common feature within the genome, rather than simple single quadruplex structures.
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Affiliation(s)
- Robert C Monsen
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - Lynn W DeLeeuw
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - William L Dean
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - Robert D Gray
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - Srinivas Chakravarthy
- The Biophysics Collaborative Access Team (BioCAT), Department of Biological, Chemical, and Physical Sciences, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Jesse B Hopkins
- The Biophysics Collaborative Access Team (BioCAT), Department of Biological, Chemical, and Physical Sciences, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Jonathan B Chaires
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
- Department of Medicine, University of Louisville, Louisville, KY 40202, USA
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY 40202, USA
| | - John O Trent
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
- Department of Medicine, University of Louisville, Louisville, KY 40202, USA
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY 40202, USA
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16
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Frasson I, Pirota V, Richter SN, Doria F. Multimeric G-quadruplexes: A review on their biological roles and targeting. Int J Biol Macromol 2022; 204:89-102. [PMID: 35124022 DOI: 10.1016/j.ijbiomac.2022.01.197] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 01/20/2022] [Accepted: 01/31/2022] [Indexed: 12/12/2022]
Abstract
In human cells, nucleic acids adopt several non-canonical structures that regulate key cellular processes. Among them, G-quadruplexes (G4s) are stable structures that form in guanine-rich regions in vitro and in cells. G4 folded/unfolded state shapes numerous cellular processes, including genome replication, transcription, and translation. Moreover, G4 folding is involved in genomic instability. G4s have been described to multimerize, forming high-order structures in both DNA and/or RNA strands. Multimeric G4s can be formed by adjacent intramolecular G4s joined by stacking interactions or connected by short loops. Multimeric G4s can also originate from the assembly of guanines embedded on independent DNA or RNA strands. Notably, crucial regions of the human genome, such as the 3'-terminal overhang of the telomeric DNA as well as the open reading frame of genes involved in the preservation of neuron viability in the human central and peripheral nervous system are prone to form multimeric G4s. The biological importance of such structures has been recently described, with multimeric G4s playing potentially protective or deleterious effects in the pathogenic cascade of various diseases. Here, we portray the multifaceted scenario of multimeric G4s, in terms of structural properties, biological roles, and targeting strategies.
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Affiliation(s)
- Ilaria Frasson
- Department of Molecular Medicine, University of Padova, via A. Gabelli 63, 35121 Padova, Italy
| | - Valentina Pirota
- Department of Chemistry, University of Pavia, v. le Taramelli 10, 27100 Pavia, Italy; G4-INTERACT, USERN, v. le Taramelli 10, 27100 Pavia, Italy
| | - Sara N Richter
- Department of Molecular Medicine, University of Padova, via A. Gabelli 63, 35121 Padova, Italy.
| | - Filippo Doria
- Department of Chemistry, University of Pavia, v. le Taramelli 10, 27100 Pavia, Italy.
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17
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Batra S, Devbhandari S, Remus D. CMG helicase activity on G4-containing DNA templates. Methods Enzymol 2022; 672:233-260. [PMID: 35934477 PMCID: PMC9578012 DOI: 10.1016/bs.mie.2022.02.020] [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] [Indexed: 11/25/2022]
Abstract
G-quadruplexes (G4s) are non-canonical nucleic acid structures that form in G-rich regions of the genome and threaten genome stability by interfering with DNA replication. However, the underlying mechanisms are poorly understood. We have recently found that G4s can stall eukaryotic replication forks by blocking the progression of replicative DNA helicase, CMG. In this paper, we detail the methodology of DNA unwinding assays to investigate the impact of G4s on CMG progression. The method details the purification of recombinantly expressed CMG from the budding yeast, Saccharomyces cerevisiae, purification of synthetic oligonucleotides, and covers various aspects of DNA substrate preparation, reaction setup and result interpretation. The use of synthetic oligonucleotides provides the advantage of allowing to control the formation of G4 structures in DNA substrates. The methods discussed here can be adapted for the study of other DNA helicases and provide a general template for the assembly of DNA substrates with distinct G4 structures.
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Affiliation(s)
- Sahil Batra
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, United States
| | - Sujan Devbhandari
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, United States
| | - Dirk Remus
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, United States.
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18
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Lomidze L, Yang M, Khutsishvili D, Metreveli N, Musier-Forsyth K, Kankia B. Structure of Tetrahelical DNA Homopolymers Supports Quadruplex World Hypothesis. ACS OMEGA 2022; 7:4311-4316. [PMID: 35155924 PMCID: PMC8829921 DOI: 10.1021/acsomega.1c06026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 12/31/2021] [Indexed: 06/14/2023]
Abstract
We previously reported a tetrahelical monomolecular architecture of DNA, tmDNA, which employs G-quartets and an all-parallel GGGTGGGTGGGTGGG (G3T) quadruplex as the repeating unit. Based on thermodynamic and kinetic studies, we proposed that covalently joined (G3T) n units formed an uninterrupted programmable homopolymer; however, structural evidence for the tmDNA architecture was lacking. Here, we used NMR spectroscopy of wild-type and single-inosine-substituted constructs to characterize both monomolecular (G3T)2 and bimolecular quadruplex-Mg-coupled versions of tmDNA. The NMR results support an architecture consisting of uninterrupted stacked G-tetrads in both the monomolecular constructs and bimolecular assemblies. Taken together, these data support the formation of a stable programmable homopolymeric tmDNA architecture, which may have been a precursor to the modern-day Watson-Crick DNA duplex.
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Affiliation(s)
- Levan Lomidze
- Institute of Biophysics, Ilia State University, Tbilisi 0162, Republic of Georgia
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Mengkun Yang
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - David Khutsishvili
- Institute of Biophysics, Ilia State University, Tbilisi 0162, Republic of Georgia
| | - Nunu Metreveli
- Institute of Biophysics, Ilia State University, Tbilisi 0162, Republic of Georgia
| | - Karin Musier-Forsyth
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Besik Kankia
- Institute of Biophysics, Ilia State University, Tbilisi 0162, Republic of Georgia
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
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19
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Beseiso D, Chen EV, McCarthy SE, Martin KN, Gallagher EP, Miao J, Yatsunyk L. OUP accepted manuscript. Nucleic Acids Res 2022; 50:2959-2972. [PMID: 35212369 PMCID: PMC8934647 DOI: 10.1093/nar/gkac091] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 01/26/2022] [Accepted: 01/28/2022] [Indexed: 11/13/2022] Open
Abstract
G-quadruplexes (GQs) are non-canonical DNA structures composed of stacks of stabilized G-tetrads. GQs play an important role in a variety of biological processes and may form at telomeres and oncogene promoters among other genomic locations. Here, we investigate nine variants of telomeric DNA from Tetrahymena thermophila with the repeat (TTGGGG)n. Biophysical data indicate that the sequences fold into stable four-tetrad GQs which adopt multiple conformations according to native PAGE. Excitingly, we solved the crystal structure of two variants, TET25 and TET26. The two variants differ by the presence of a 3′-T yet adopt different GQ conformations. TET25 forms a hybrid [3 + 1] GQ and exhibits a rare 5′-top snapback feature. Consequently, TET25 contains four loops: three lateral (TT, TT, and GTT) and one propeller (TT). TET26 folds into a parallel GQ with three TT propeller loops. To the best of our knowledge, TET25 and TET26 are the first reported hybrid and parallel four-tetrad unimolecular GQ structures. The results presented here expand the repertoire of available GQ structures and provide insight into the intricacy and plasticity of the 3D architecture adopted by telomeric repeats from T. thermophila and GQs in general.
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Affiliation(s)
- Dana Beseiso
- Department of Chemistry and Biochemistry, Swarthmore College, 500 College Ave, Swarthmore, PA 19081, USA
| | - Erin V Chen
- Department of Chemistry and Biochemistry, Swarthmore College, 500 College Ave, Swarthmore, PA 19081, USA
| | - Sawyer E McCarthy
- Department of Chemistry and Biochemistry, Swarthmore College, 500 College Ave, Swarthmore, PA 19081, USA
| | - Kailey N Martin
- Department of Chemistry and Biochemistry, Swarthmore College, 500 College Ave, Swarthmore, PA 19081, USA
| | - Elizabeth P Gallagher
- Department of Chemistry and Biochemistry, Swarthmore College, 500 College Ave, Swarthmore, PA 19081, USA
| | - Joanne Miao
- Department of Chemistry and Biochemistry, Swarthmore College, 500 College Ave, Swarthmore, PA 19081, USA
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20
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Guo X, Chen H, Liu Y, Yang D, Li Q, Du H, Liu M, Tang Y, Sun H. An organic molecular compound for in situ identification of mitochondrial G-quadruplexes in live cells. J Mater Chem B 2021; 10:430-437. [PMID: 34940779 DOI: 10.1039/d1tb02296b] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Emerging studies have shown that mitochondrial G-quadruplex plays a critical role in regulating mitochondrial gene replication and transcription, which makes it a promising target for the diagnosis and treatment of cancer or other major diseases. Molecular compounds that can highly target the mitochondrial G-quadruplexes in live cells are essential for further revealing the function and mechanism of these G-quadruplexes. Here, we have developed an organic molecular compound that can highly target the mitochondria of living cells by virtue of the membrane potential mechanism. Then it shows high selectivity to the G-quadruplex structure in the mitochondria, and its fluorescence overlaps well with that of the BG4 antibody. Moreover, the compound has extremely low cytotoxicity and does not interfere with the natural state of G-quadruplex structure. With these good properties, this compound will have great potential in mitochondrial G-quadruplex tracking research or targeted drug screening.
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Affiliation(s)
- Xiaomeng Guo
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry Chinese Academy of Sciences, Beijing, 100190, P. R. China. .,University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.,Basic Medical Science, Shenyang Medical college, Shenyang, 110034, P. R. China
| | - Hongbo Chen
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry Chinese Academy of Sciences, Beijing, 100190, P. R. China. .,University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Yan Liu
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry Chinese Academy of Sciences, Beijing, 100190, P. R. China.
| | - Dawei Yang
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry Chinese Academy of Sciences, Beijing, 100190, P. R. China. .,University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Qian Li
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry Chinese Academy of Sciences, Beijing, 100190, P. R. China.
| | - Hongyan Du
- Institute of Forensic Science, Ministry of Public Security, Beijing, 100038, P. R. China
| | - Meirong Liu
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry Chinese Academy of Sciences, Beijing, 100190, P. R. China.
| | - Yalin Tang
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry Chinese Academy of Sciences, Beijing, 100190, P. R. China. .,University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Hongxia Sun
- Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry Chinese Academy of Sciences, Beijing, 100190, P. R. China. .,University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
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21
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Largy E, König A, Ghosh A, Ghosh D, Benabou S, Rosu F, Gabelica V. Mass Spectrometry of Nucleic Acid Noncovalent Complexes. Chem Rev 2021; 122:7720-7839. [PMID: 34587741 DOI: 10.1021/acs.chemrev.1c00386] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Nucleic acids have been among the first targets for antitumor drugs and antibiotics. With the unveiling of new biological roles in regulation of gene expression, specific DNA and RNA structures have become very attractive targets, especially when the corresponding proteins are undruggable. Biophysical assays to assess target structure as well as ligand binding stoichiometry, affinity, specificity, and binding modes are part of the drug development process. Mass spectrometry offers unique advantages as a biophysical method owing to its ability to distinguish each stoichiometry present in a mixture. In addition, advanced mass spectrometry approaches (reactive probing, fragmentation techniques, ion mobility spectrometry, ion spectroscopy) provide more detailed information on the complexes. Here, we review the fundamentals of mass spectrometry and all its particularities when studying noncovalent nucleic acid structures, and then review what has been learned thanks to mass spectrometry on nucleic acid structures, self-assemblies (e.g., duplexes or G-quadruplexes), and their complexes with ligands.
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Affiliation(s)
- Eric Largy
- Univ. Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Pessac, France
| | - Alexander König
- Univ. Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Pessac, France
| | - Anirban Ghosh
- Univ. Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Pessac, France
| | - Debasmita Ghosh
- Univ. Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Pessac, France
| | - Sanae Benabou
- Univ. Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Pessac, France
| | - Frédéric Rosu
- Univ. Bordeaux, CNRS, INSERM, IECB, UMS 3033, F-33600 Pessac, France
| | - Valérie Gabelica
- Univ. Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Pessac, France
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22
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Asha H, Green JA, Martinez-Fernandez L, Esposito L, Improta R. Electronic Circular Dichroism Spectra of DNA Quadruple Helices Studied by Molecular Dynamics Simulations and Excitonic Calculations including Charge Transfer States. Molecules 2021; 26:molecules26164789. [PMID: 34443377 PMCID: PMC8398971 DOI: 10.3390/molecules26164789] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 08/03/2021] [Accepted: 08/04/2021] [Indexed: 11/18/2022] Open
Abstract
We here investigate the Electronic Circular Dichroism (ECD) Spectra of two representative Guanine-rich sequences folded in a Quadruple helix (GQ), by using a recently developed fragment diabatisation based excitonic model (FrDEx). FrDEx can include charge transfer (CT) excited states and consider the effect of the surrounding monomers on the local excitations (LEs). When applied to different structures generated by molecular dynamics simulations on a fragment of the human telomeric sequence (Tel21/22), FrDEx provides spectra fully consistent with the experimental one and in good agreement with that provided by quantum mechanical (QM) method used for its parametrization, i.e., TD-M05-2X. We show that the ECD spectrum is moderately sensitive to the conformation adopted by the bases of the loops and more significantly to the thermal fluctuations of the Guanine tetrads. In particular, we show how changes in the overlap of the tetrads modulate the intensity of the ECD signal. We illustrate how this correlates with changes in the character of the excitonic states at the bottom of the La and Lb bands, with larger LE and CT involvement of bases that are more closely stacked. As an additional test, we utilised FrDEx to compute the ECD spectrum of the monomeric and dimeric forms of a GQ forming sequence T30695 (5′TGGGTGGGTGGGTGGG3′), i.e., a system containing up to 24 Guanine bases, and demonstrated the satisfactory reproduction of the experimental and QM reference results. This study provides new insights on the effects modulating the ECD spectra of GQs and, more generally, further validates FrDEx as an effective tool to predict and assign the spectra of closely stacked multichromophore systems.
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Affiliation(s)
- Haritha Asha
- CNR—Consiglio Nazionale delle Ricerche, Istituto di Biostrutture e Bioimmagini (IBB-CNR), Via Mezzocannone 16, I-80136 Napoli, Italy; (H.A.); (J.A.G.); (L.E.)
| | - James A. Green
- CNR—Consiglio Nazionale delle Ricerche, Istituto di Biostrutture e Bioimmagini (IBB-CNR), Via Mezzocannone 16, I-80136 Napoli, Italy; (H.A.); (J.A.G.); (L.E.)
| | - Lara Martinez-Fernandez
- Departamento de Química, Facultad de Ciencias and IADCHEM (Institute for Advanced Research in Chemistry), Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain;
| | - Luciana Esposito
- CNR—Consiglio Nazionale delle Ricerche, Istituto di Biostrutture e Bioimmagini (IBB-CNR), Via Mezzocannone 16, I-80136 Napoli, Italy; (H.A.); (J.A.G.); (L.E.)
| | - Roberto Improta
- CNR—Consiglio Nazionale delle Ricerche, Istituto di Biostrutture e Bioimmagini (IBB-CNR), Via Mezzocannone 16, I-80136 Napoli, Italy; (H.A.); (J.A.G.); (L.E.)
- Correspondence:
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23
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Rhodamine 6G-Ligand Influencing G-Quadruplex Stability and Topology. Int J Mol Sci 2021; 22:ijms22147639. [PMID: 34299257 PMCID: PMC8305571 DOI: 10.3390/ijms22147639] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 07/09/2021] [Accepted: 07/15/2021] [Indexed: 11/17/2022] Open
Abstract
The involvement of G-quadruplex (G4) structures in nucleic acids in various molecular processes in cells such as replication, gene-pausing, the expression of crucial cancer-related genes and DNA damage repair is well known. The compounds targeting G4 usually bind directly to the G4 structure, but some ligands can also facilitate the G4 folding of unfolded G-rich sequences and stabilize them even without the presence of monovalent ions such as sodium or potassium. Interestingly, some G4-ligand complexes can show a clear induced CD signal, a feature which is indirect proof of the ligand interaction. Based on the dichroic spectral profile it is not only possible to confirm the presence of a G4 structure but also to determine its topology. In this study we examine the potential of the commercially available Rhodamine 6G (RhG) as a G4 ligand. RhG tends to convert antiparallel G4 structures to parallel forms in a manner similar to that of Thiazole Orange. Our results confirm the very high selectivity of this ligand to the G4 structure. Moreover, the parallel topology of G4 can be verified unambiguously based on the specific induced CD profile of the G4-RhG complex. This feature has been verified on more than 50 different DNA sequences forming various non-canonical structural motifs.
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24
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Pruška A, Marchand A, Zenobi R. Novel Insight into Proximal DNA Domain Interactions from Temperature-Controlled Electrospray Ionization Mass Spectrometry. Angew Chem Int Ed Engl 2021; 60:15390-15398. [PMID: 33822450 PMCID: PMC8251475 DOI: 10.1002/anie.202016757] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 03/07/2021] [Indexed: 01/05/2023]
Abstract
Quadruplexes are non-canonical nucleic acid structures essential for many cellular processes. Hybrid quadruplex-duplex oligonucleotide assemblies comprised of multiple domains are challenging to study with conventional biophysical methods due to their structural complexity. Here, we introduce a novel method based on native mass spectrometry (MS) coupled with a custom-built temperature-controlled nanoelectrospray ionization (TCnESI) source designed to investigate interactions between proximal DNA domains. Thermal denaturation experiments were aimed to study unfolding of multi-stranded oligonucleotide constructs derived from biologically relevant structures and to identify unfolding intermediates. Using the TCnESI MS, we observed changes in Tm and thermodynamic characteristics of proximal DNA domains depending on the number of domains, their position, and order in a single experiment.
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Affiliation(s)
- Adam Pruška
- Department of Chemistry and Applied BiosciencesETH ZurichVladimir-Prelog-Weg 38093ZurichSwitzerland
| | - Adrien Marchand
- Department of Chemistry and Applied BiosciencesETH ZurichVladimir-Prelog-Weg 38093ZurichSwitzerland
| | - Renato Zenobi
- Department of Chemistry and Applied BiosciencesETH ZurichVladimir-Prelog-Weg 38093ZurichSwitzerland
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25
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Pruška A, Marchand A, Zenobi R. Novel Insight into Proximal DNA Domain Interactions from Temperature‐Controlled Electrospray Ionization Mass Spectrometry. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202016757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Adam Pruška
- Department of Chemistry and Applied Biosciences ETH Zurich Vladimir-Prelog-Weg 3 8093 Zurich Switzerland
| | - Adrien Marchand
- Department of Chemistry and Applied Biosciences ETH Zurich Vladimir-Prelog-Weg 3 8093 Zurich Switzerland
| | - Renato Zenobi
- Department of Chemistry and Applied Biosciences ETH Zurich Vladimir-Prelog-Weg 3 8093 Zurich Switzerland
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26
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Abstract
The RNA world hypothesis relies on the double-helix complementarity principle for both replication and catalytic activity of RNA. However, the de novo appearance of the complementarity rules, without previous evolution steps, is doubtful. Another major problem of the RNA world is its isolated nature, making it almost impossible to accommodate the genetic code and transform it into modern biochemistry. These and many other unanswered questions of the RNA world led to suggestions that some simpler molecules must have preceded RNA. Most of these alternative hypotheses proposed the double-helical polymers with different backbones but used the same complementarity principle. The current paper describes a fundamentally different idea: the de novo appearance of a nucleic acid polymer without any preexisting rules or requirements. This approach, coined as the quadruplex world hypothesis, is based on (i) the ability of guanines to form stable G-tetrads that facilitate polymerization; and (ii) the unique property of polyguanines to fold into a monomolecular tetrahelix with a strictly defined building pattern and tertiary structure. The tetrahelix is capable of high-affinity intermolecular interactions and catalytic activities. The quadruplex world hypothesis has the potential to address almost all the shortcomings of the RNA world.
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Affiliation(s)
- Besik Kankia
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, USA. .,Institute of Biophysics, Ilia State University, Tbilisi, 0162, Republic of Georgia.
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Virgilio A, Benigno D, Pecoraro A, Russo A, Russo G, Esposito V, Galeone A. Exploring New Potential Anticancer Activities of the G-Quadruplexes Formed by [(GTG 2T(G 3T) 3] and Its Derivatives with an Abasic Site Replacing Single Thymidine. Int J Mol Sci 2021; 22:ijms22137040. [PMID: 34208896 PMCID: PMC8268168 DOI: 10.3390/ijms22137040] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 06/17/2021] [Accepted: 06/23/2021] [Indexed: 12/27/2022] Open
Abstract
In this paper, we report our investigations on five T30175 analogues, prepared by replacing sequence thymidines with abasic sites (S) one at a time, in comparison to their natural counterpart in order to evaluate their antiproliferative potential and the involvement of the residues not belonging to the central core of stacked guanosines in biological activity. The collected NMR (Nuclear Magnetic Resonance), CD (Circular Dichroism), and PAGE (Polyacrylamide Gel Electrophoresis) data strongly suggest that all of them adopt G-quadruplex (G4) structures strictly similar to that of the parent aptamer with the ability to fold into a dimeric structure composed of two identical G-quadruplexes, each characterized by parallel strands, three all-anti-G-tetrads and four one-thymidine loops (one bulge and three propeller loops). Furthermore, their antiproliferative (MTT assay) and anti-motility (wound healing assay) properties against lung and colorectal cancer cells were tested. Although all of the oligodeoxynucleotides (ODNs) investigated here exhibited anti-proliferative activity, the unmodified T30175 aptamer showed the greatest effect on cell growth, suggesting that both its characteristic folding in dimeric form and its presence in the sequence of all thymidines are crucial elements for antiproliferative activity. This straightforward approach is suitable for understanding the critical requirements of the G-quadruplex structures that affect antiproliferative potential and suggests its application as a starting point to facilitate the reasonable development of G-quadruplexes with improved anticancer properties.
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Supramolecular Polymorphism of (G 4C 2) n Repeats Associated with ALS and FTD. Int J Mol Sci 2021; 22:ijms22094532. [PMID: 33926081 PMCID: PMC8123662 DOI: 10.3390/ijms22094532] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 04/21/2021] [Accepted: 04/23/2021] [Indexed: 12/25/2022] Open
Abstract
Guanine-rich DNA sequences self-assemble into highly stable fourfold structures known as DNA-quadruplexes (or G-quadruplexes). G-quadruplexes have furthermore the tendency to associate into one-dimensional supramolecular aggregates termed G-wires. We studied the formation of G-wires in solutions of the sequences d(G4C2)n with n = 1, 2, and 4. The d(G4C2)n repeats, which are associated with some fatal neurological disorders, especially amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), represent a challenging research topic due to their extensive structural polymorphism. We used dynamic light scattering (DLS) to measure translational diffusion coefficients and consequently resolve the length of the larger aggregates formed in solution. We found that all three sequences assemble into longer structures than previously reported. The d(G4C2) formed extremely long G-wires with lengths beyond 80 nm. The d(G4C2)2 formed a relatively short stacked dimeric quadruplex, while d(G4C2)4 formed multimers corresponding to seven stacked intramolecular quadruplexes. Profound differences between the multimerization properties of the investigated sequences were also confirmed by the AFM imaging of surface films. We propose that π-π stacking of the basic G-quadruplex units plays a vital role in the multimerization mechanism, which might be relevant for transformation from the regular medium-length to disease-related long d(G4C2)n repeats.
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29
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Abstract
![]()
Clustered regularly
interspaced palindromic repeats (CRISPR) and
CRISPR-associated (Cas) proteins, particularly Cas9, have provided
unprecedented control on targeting and editing specific DNA sequences.
If the target sequences are prone to folding into noncanonical secondary
structures, such as G-quadruplex (GQ), the conformational states and
activity of the CRISPR–Cas9 complex may be influenced, but
the impact has not been assessed. Using single molecule FRET, we investigated
structural characteristics of the complex formed by CRISPR–Cas9
and target DNA, which contains a potentially GQ forming sequence (PQS)
in either the target or the nontarget strand (TS or NTS). We observed
different conformational states and dynamics depending on the stability
of the GQ and the position of PQS. When PQS was in NTS, we observed
evidence for GQ formation for both weak and stable GQs. This is consistent
with R-loop formation between TS and crRNA releasing NTS from Watson–Crick
pairing and facilitating secondary structure formation in it. When
PQS was in TS, R-loop formation was adequate to maintain a weak GQ
in the unfolded state but not a GQ with moderate or high stability.
The observed structural heterogeneity within the target dsDNA and
the R-loop strongly depended on whether the PQS was in TS or NTS.
We propose these variations in the complex structures to have functional
implications for Cas9 activity.
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Affiliation(s)
- Hamza Balci
- Department of Physics, Kent State University, Kent, Ohio 44242, United States
- Kavli Institute of NanoScience and Department of BioNanoScience, Delft University of Technology, Delft, 2629HZ, The Netherlands
| | - Viktorija Globyte
- Kavli Institute of NanoScience and Department of BioNanoScience, Delft University of Technology, Delft, 2629HZ, The Netherlands
| | - Chirlmin Joo
- Kavli Institute of NanoScience and Department of BioNanoScience, Delft University of Technology, Delft, 2629HZ, The Netherlands
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Cagirici HB, Budak H, Sen TZ. Genome-wide discovery of G-quadruplexes in barley. Sci Rep 2021; 11:7876. [PMID: 33846409 PMCID: PMC8041835 DOI: 10.1038/s41598-021-86838-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 03/19/2021] [Indexed: 12/04/2022] Open
Abstract
G-quadruplexes (G4s) are four-stranded nucleic acid structures with closely spaced guanine bases forming square planar G-quartets. Aberrant formation of G4 structures has been associated with genomic instability. However, most plant species are lacking comprehensive studies of G4 motifs. In this study, genome-wide identification of G4 motifs in barley was performed, followed by a comparison of genomic distribution and molecular functions to other monocot species, such as wheat, maize, and rice. Similar to the reports on human and some plants like wheat, G4 motifs peaked around the 5′ untranslated region (5′ UTR), the first coding domain sequence, and the first intron start sites on antisense strands. Our comparative analyses in human, Arabidopsis, maize, rice, and sorghum demonstrated that the peak points could be erroneously merged into a single peak when large window sizes are used. We also showed that the G4 distributions around genic regions are relatively similar in the species studied, except in the case of Arabidopsis. G4 containing genes in monocots showed conserved molecular functions for transcription initiation and hydrolase activity. Additionally, we provided examples of imperfect G4 motifs.
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Affiliation(s)
- H Busra Cagirici
- Crop Improvement and Genetics Research Unit, Western Regional Research Center, U.S. Department of Agriculture - Agricultural Research Service, 800 Buchanan St, Albany, CA, 94710, USA
| | - Hikmet Budak
- Montana BioAg Inc., Missoula, MT, USA.,Agrogen, LLC., Omaha, NE, USA
| | - Taner Z Sen
- Crop Improvement and Genetics Research Unit, Western Regional Research Center, U.S. Department of Agriculture - Agricultural Research Service, 800 Buchanan St, Albany, CA, 94710, USA.
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Jana J, Mohr S, Vianney YM, Weisz K. Structural motifs and intramolecular interactions in non-canonical G-quadruplexes. RSC Chem Biol 2021; 2:338-353. [PMID: 34458788 PMCID: PMC8341446 DOI: 10.1039/d0cb00211a] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 01/14/2021] [Indexed: 12/12/2022] Open
Abstract
Guanine(G)-rich DNA or RNA sequences can assemble or intramolecularly fold into G-quadruplexes formed through the stacking of planar G·G·G·G tetrads in the presence of monovalent cations. These secondary nucleic acid structures have convincingly been shown to also exist within a cellular environment exerting important regulatory functions in physiological processes. For identifying nucleic acid segments prone to quadruplex formation, a putative quadruplex sequence motif encompassing closely spaced tracts of three or more guanosines is frequently employed for bioinformatic search algorithms. Depending on the number and type of intervening residues as well as on solution conditions, such sequences may fold into various canonical G4 topologies with continuous G-columns. On the other hand, a growing number of sequences capable of quadruplex formation feature G-deficient guanine tracts, escaping the conservative consensus motif. By folding into non-canonical quadruplex structures, they adopt unique topologies depending on their specific sequence context. These include G-columns with only two guanines, bulges, snapback loops, D- and V-shaped loops as well as interlocked structures. This review focuses on G-quadruplex species carrying such distinct structural motifs. It evaluates characteristic features of their non-conventional scaffold and highlights principles of stabilizing interactions that also allow for their folding into stable G-quadruplex structures.
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Affiliation(s)
- Jagannath Jana
- Institute of Biochemistry, Universität Greifswald Felix-Hausdorff-Str. 4 D-17487 Greifswald Germany +49 3834 420-4427 +49 3834 420-4426
| | - Swantje Mohr
- Institute of Biochemistry, Universität Greifswald Felix-Hausdorff-Str. 4 D-17487 Greifswald Germany +49 3834 420-4427 +49 3834 420-4426
| | - Yoanes Maria Vianney
- Institute of Biochemistry, Universität Greifswald Felix-Hausdorff-Str. 4 D-17487 Greifswald Germany +49 3834 420-4427 +49 3834 420-4426
| | - Klaus Weisz
- Institute of Biochemistry, Universität Greifswald Felix-Hausdorff-Str. 4 D-17487 Greifswald Germany +49 3834 420-4427 +49 3834 420-4426
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32
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Covalent Bi-Modular Parallel and Antiparallel G-Quadruplex DNA Nanocostructs Reduce Viability of Patient Glioma Primary Cell Cultures. Int J Mol Sci 2021; 22:ijms22073372. [PMID: 33806042 PMCID: PMC8036578 DOI: 10.3390/ijms22073372] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 03/19/2021] [Accepted: 03/22/2021] [Indexed: 12/22/2022] Open
Abstract
G-quadruplex oligonucleotides (GQs) exhibit specific anti-proliferative activity in human cancer cell lines, and they can selectively inhibit the viability/proliferation of cancer cell lines vs. non-cancer ones. This ability could be translated into a cancer treatment, in particular for glioblastoma multiform (GBM), which currently has a poor prognosis and low-efficiency therapeutic treatments. A novel bi-modular GQ, bi-(AID-1-T), a twin of the previously described three-quartet AID-1-T, was designed and studied in terms of both its structure and function. A covalent conjugation of two AID-1-Ts via three thymidine link, TTT, did not interfere with its initial GQ structure. A comparison of bi-(AID-1-T) with its mono-modular AID-1-T, mono-modular two-quartet HD1, and bi-modular bi-HD1, as well as conventional two-quartet AS1411, was made. Among the five GQs studied, bi-(AID-1-T) had the highest anti-proliferative activity for the neural cancer cell line U87, while not affecting the control cell line, human embryonic fibroblasts. GQs, for the first time, were tested on several primary glioma cultures from patient surgical samples. It turned out that the sensitivity of the patient primary glioma cultures toward GQs varied, with an apparent IC50 of less than 1 μM for bi-(AID-1-T) toward the most sensitive G11 cell culture (glioma, Grade III).
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O’ Sullivan CK, Mairal T, Jauset-Rubio M, Svobodova M, Skouridou V, Esposito V, Virgilio A, Galeone A. Aptamers against the β-Conglutin Allergen: Insights into the Behavior of the Shortest Multimeric (Intra)Molecular DNA G-Quadruplex. Int J Mol Sci 2021; 22:ijms22031150. [PMID: 33498970 PMCID: PMC7865891 DOI: 10.3390/ijms22031150] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 01/13/2021] [Accepted: 01/19/2021] [Indexed: 01/25/2023] Open
Abstract
In previous work, a 93-mer aptamer was selected against the anaphylactic allergen, β-conglutin and truncated to an 11-mer, improving the affinity by two orders of magnitude, whilst maintaining the specificity. This 11-mer was observed to fold in a G-quadruplex, and preliminary results indicated the existence of a combination of monomeric and higher-order structures. Building on this previous work, in the current study, we aimed to elucidate a deeper understanding of the structural forms of this 11-mer and the effect of the structure on its binding ability. A battery of techniques including polyacrylamide gel electrophoresis, high-performance liquid chromatography in combination with electrospray ionization time-of-flight mass spectrometry, matrix-assisted laser desorption/ionization time-of-flight, thermal binding analysis, circular dichroism and nuclear magnetic resonance were used to probe the structure of both the 11-mer and the 11-mer flanked with TT- at either the 5′ or 3′ end or at both ends. The TT-tail at the 5′ end hinders stacking effects and effectively enforces the 11-mer to maintain a monomeric form. The 11-mer and the TT- derivatives of the 11-mer were also evaluated for their ability to bind its cognate target using microscale thermophoresis and surface plasmon resonance, and biolayer interferometry confirmed the nanomolar affinity of the 11-mer. All the techniques utilized confirmed that the 11-mer was found to exist in a combination of monomeric and higher-order structures, and that independent of the structural form present, nanomolar affinity was observed.
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Affiliation(s)
- Ciara K. O’ Sullivan
- INTERFIBIO Research Group, Departament d’Enginyeria Química, Universitat Rovira i Virgili, Avinguda Països Catalans 26, 43007 Tarragona, Spain; (T.M.); (M.J.-R.); (M.S.); (V.S.)
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig Lluís Companys 23, 08010 Barcelona, Spain
- Correspondence:
| | - Teresa Mairal
- INTERFIBIO Research Group, Departament d’Enginyeria Química, Universitat Rovira i Virgili, Avinguda Països Catalans 26, 43007 Tarragona, Spain; (T.M.); (M.J.-R.); (M.S.); (V.S.)
| | - Miriam Jauset-Rubio
- INTERFIBIO Research Group, Departament d’Enginyeria Química, Universitat Rovira i Virgili, Avinguda Països Catalans 26, 43007 Tarragona, Spain; (T.M.); (M.J.-R.); (M.S.); (V.S.)
| | - Marketa Svobodova
- INTERFIBIO Research Group, Departament d’Enginyeria Química, Universitat Rovira i Virgili, Avinguda Països Catalans 26, 43007 Tarragona, Spain; (T.M.); (M.J.-R.); (M.S.); (V.S.)
| | - Vasso Skouridou
- INTERFIBIO Research Group, Departament d’Enginyeria Química, Universitat Rovira i Virgili, Avinguda Països Catalans 26, 43007 Tarragona, Spain; (T.M.); (M.J.-R.); (M.S.); (V.S.)
| | - Veronica Esposito
- Dipartimento di Farmacia, Università degli Studi di Napoli Federico II, Via D. Montesano 49, 80131 Napoli, Italy; (V.E.); (A.V.); (A.G.)
| | - Antonella Virgilio
- Dipartimento di Farmacia, Università degli Studi di Napoli Federico II, Via D. Montesano 49, 80131 Napoli, Italy; (V.E.); (A.V.); (A.G.)
| | - Aldo Galeone
- Dipartimento di Farmacia, Università degli Studi di Napoli Federico II, Via D. Montesano 49, 80131 Napoli, Italy; (V.E.); (A.V.); (A.G.)
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Ojha YR, Giovannucci DR, Cameron BD. Selection and characterization of structure-switching DNA aptamers for the salivary peptide histatin 3. J Biotechnol 2020; 327:9-17. [PMID: 33387594 DOI: 10.1016/j.jbiotec.2020.12.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 11/10/2020] [Accepted: 12/24/2020] [Indexed: 12/21/2022]
Abstract
In this study, single-stranded DNA aptamers that switch structural conformation upon binding to the salivary peptide histatin 3 have been reported for the first time. Histatin 3 is an antimicrobial peptide that possesses the capability of being a therapeutic agent against oral candidiasis and has recently been linked as a novel biomarker for acute stress. The aptamers were identified through a library immobilization version of an iterative in vitro process known as the Systematic Evolution of Ligands by EXponential enrichment (SELEX). Through the SELEX process, four unique aptamer candidates sharing a consensus sequence were identified. These selected sequences exhibited binding affinity and specificity to histatin 3 and in order to further characterize these aptamers, a direct format enzyme-linked aptamer sorbent assay (ELASA) was developed. The best performing candidate demonstrated an equilibrium dissociation constant (Kd) value of 1.97 ± 0.48 μM. These novel aptamers have the potential to lead to the further development of refined sensing assays and platforms for the detection and quantification of histatin 3 in human saliva and other biological media.
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Affiliation(s)
- Yagya R Ojha
- Department of Bioengineering, University of Toledo, Toledo, OH 43606, USA
| | | | - Brent D Cameron
- Department of Bioengineering, University of Toledo, Toledo, OH 43606, USA.
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35
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Responses of DNA Mismatch Repair Proteins to a Stable G-Quadruplex Embedded into a DNA Duplex Structure. Int J Mol Sci 2020; 21:ijms21228773. [PMID: 33233554 PMCID: PMC7699706 DOI: 10.3390/ijms21228773] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 11/16/2020] [Accepted: 11/18/2020] [Indexed: 12/26/2022] Open
Abstract
DNA mismatch repair (MMR) plays a crucial role in the maintenance of genomic stability. The main MMR protein, MutS, was recently shown to recognize the G-quadruplex (G4) DNA structures, which, along with regulatory functions, have a negative impact on genome integrity. Here, we studied the effect of G4 on the DNA-binding activity of MutS from Rhodobacter sphaeroides (methyl-independent MMR) in comparison with MutS from Escherichia coli (methyl-directed MMR) and evaluated the influence of a G4 on the functioning of other proteins involved in the initial steps of MMR. For this purpose, a new DNA construct was designed containing a biologically relevant intramolecular stable G4 structure flanked by double-stranded regions with the set of DNA sites required for MMR initiation. The secondary structure of this model was examined using NMR spectroscopy, chemical probing, fluorescent indicators, circular dichroism, and UV spectroscopy. The results unambiguously showed that the d(GGGT)4 motif, when embedded in a double-stranded context, adopts a G4 structure of a parallel topology. Despite strong binding affinities of MutS and MutL for a G4, the latter is not recognized by E. coli MMR as a signal for repair, but does not prevent MMR processing when a G4 and G/T mismatch are in close proximity.
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Buglak AA, Samokhvalov AV, Zherdev AV, Dzantiev BB. Methods and Applications of In Silico Aptamer Design and Modeling. Int J Mol Sci 2020; 21:E8420. [PMID: 33182550 PMCID: PMC7698023 DOI: 10.3390/ijms21228420] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 11/04/2020] [Accepted: 11/08/2020] [Indexed: 02/07/2023] Open
Abstract
Aptamers are nucleic acid analogues of antibodies with high affinity to different targets, such as cells, viruses, proteins, inorganic materials, and coenzymes. Empirical approaches allow the design of in vitro aptamers that bind particularly to a target molecule with high affinity and selectivity. Theoretical methods allow significant expansion of the possibilities of aptamer design. In this study, we review theoretical and joint theoretical-experimental studies dedicated to aptamer design and modeling. We consider aptamers with different targets, such as proteins, antibiotics, organophosphates, nucleobases, amino acids, and drugs. During nucleic acid modeling and in silico design, a full set of in silico methods can be applied, such as docking, molecular dynamics (MD), and statistical analysis. The typical modeling workflow starts with structure prediction. Then, docking of target and aptamer is performed. Next, MD simulations are performed, which allows for an evaluation of the stability of aptamer/ligand complexes and determination of the binding energies with higher accuracy. Then, aptamer/ligand interactions are analyzed, and mutations of studied aptamers made. Subsequently, the whole procedure of molecular modeling can be reiterated. Thus, the interactions between aptamers and their ligands are complex and difficult to understand using only experimental approaches. Docking and MD are irreplaceable when aptamers are studied in silico.
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Affiliation(s)
- Andrey A. Buglak
- A. N. Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Leninsky prospect 33, 119071 Moscow, Russia; (A.V.S.); (A.V.Z.); (B.B.D.)
- Physical Faculty, St. Petersburg State University, 7/9 Universitetskaya naberezhnaya, 199034 St. Petersburg, Russia
| | - Alexey V. Samokhvalov
- A. N. Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Leninsky prospect 33, 119071 Moscow, Russia; (A.V.S.); (A.V.Z.); (B.B.D.)
| | - Anatoly V. Zherdev
- A. N. Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Leninsky prospect 33, 119071 Moscow, Russia; (A.V.S.); (A.V.Z.); (B.B.D.)
| | - Boris B. Dzantiev
- A. N. Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Leninsky prospect 33, 119071 Moscow, Russia; (A.V.S.); (A.V.Z.); (B.B.D.)
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37
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Riccardi C, Napolitano E, Musumeci D, Montesarchio D. Dimeric and Multimeric DNA Aptamers for Highly Effective Protein Recognition. Molecules 2020; 25:E5227. [PMID: 33182593 PMCID: PMC7698228 DOI: 10.3390/molecules25225227] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 11/06/2020] [Accepted: 11/08/2020] [Indexed: 12/14/2022] Open
Abstract
Multivalent interactions frequently occur in biological systems and typically provide higher binding affinity and selectivity in target recognition than when only monovalent interactions are operative. Thus, taking inspiration by nature, bivalent or multivalent nucleic acid aptamers recognizing a specific biological target have been extensively studied in the last decades. Indeed, oligonucleotide-based aptamers are suitable building blocks for the development of highly efficient multivalent systems since they can be easily modified and assembled exploiting proper connecting linkers of different nature. Thus, substantial research efforts have been put in the construction of dimeric/multimeric versions of effective aptamers with various degrees of success in target binding affinity or therapeutic activity enhancement. The present review summarizes recent advances in the design and development of dimeric and multimeric DNA-based aptamers, including those forming G-quadruplex (G4) structures, recognizing different key proteins in relevant pathological processes. Most of the designed constructs have shown improved performance in terms of binding affinity or therapeutic activity as anti-inflammatory, antiviral, anticoagulant, and anticancer agents and their number is certainly bound to grow in the next future.
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Affiliation(s)
- Claudia Riccardi
- Department of Chemical Sciences, University of Naples Federico II, via Cintia 21, I-80126 Naples, Italy; (E.N.); (D.M.); (D.M.)
- Department of Advanced Medical and Surgical Sciences, 2nd Division of Neurology, Center for Rare Diseases and InterUniversity Center for Research in Neurosciences, University of Campania Luigi Vanvitelli, via Sergio Pansini, 5, I-80131 Naples, Italy
| | - Ettore Napolitano
- Department of Chemical Sciences, University of Naples Federico II, via Cintia 21, I-80126 Naples, Italy; (E.N.); (D.M.); (D.M.)
| | - Domenica Musumeci
- Department of Chemical Sciences, University of Naples Federico II, via Cintia 21, I-80126 Naples, Italy; (E.N.); (D.M.); (D.M.)
- Institute of Biostructures and Bioimages, CNR, via Mezzocannone 16, I-80134 Naples, Italy
| | - Daniela Montesarchio
- Department of Chemical Sciences, University of Naples Federico II, via Cintia 21, I-80126 Naples, Italy; (E.N.); (D.M.); (D.M.)
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38
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Ogloblina AM, Iaccarino N, Capasso D, Di Gaetano S, Garzarella EU, Dolinnaya NG, Yakubovskaya MG, Pagano B, Amato J, Randazzo A. Toward G-Quadruplex-Based Anticancer Agents: Biophysical and Biological Studies of Novel AS1411 Derivatives. Int J Mol Sci 2020; 21:E7781. [PMID: 33096752 PMCID: PMC7590035 DOI: 10.3390/ijms21207781] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 10/17/2020] [Accepted: 10/19/2020] [Indexed: 12/16/2022] Open
Abstract
Certain G-quadruplex forming guanine-rich oligonucleotides (GROs), including AS1411, are endowed with cancer-selective antiproliferative activity. They are known to bind to nucleolin protein, resulting in the inhibition of nucleolin-mediated phenomena. However, multiple nucleolin-independent biological effects of GROs have also been reported, allowing them to be considered promising candidates for multi-targeted cancer therapy. Herein, with the aim of optimizing AS1411 structural features to find GROs with improved anticancer properties, we have studied a small library of AS1411 derivatives differing in the sequence length and base composition. The AS1411 derivatives were characterized by using circular dichroism and nuclear magnetic resonance spectroscopies and then investigated for their enzymatic resistance in serum and nuclear extract, as well as for their ability to bind nucleolin, inhibit topoisomerase I, and affect the viability of MCF-7 human breast adenocarcinoma cells. All derivatives showed higher thermal stability and inhibitory effect against topoisomerase I than AS1411. In addition, most of them showed an improved antiproliferative activity on MCF-7 cells compared to AS1411 despite a weaker binding to nucleolin. Our results support the hypothesis that the antiproliferative properties of GROs are due to multi-targeted effects.
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Affiliation(s)
- Anna M. Ogloblina
- N.N. Blokhin National Medical Research Center of Oncology, Ministry of Health, 115478 Moscow, Russia; (A.M.O.); (M.G.Y.)
- Department of Pharmacy, University of Naples Federico II, Via D. Montesano 49, 80131 Naples, Italy; (N.I.); (E.U.G.); (A.R.)
| | - Nunzia Iaccarino
- Department of Pharmacy, University of Naples Federico II, Via D. Montesano 49, 80131 Naples, Italy; (N.I.); (E.U.G.); (A.R.)
| | - Domenica Capasso
- Center for Life Sciences and Technologies (CESTEV), University of Naples Federico II, Via A. De Amicis 95, 80145 Naples, Italy;
| | - Sonia Di Gaetano
- Institute of Biostructures and Bioimaging, National Research Council, Via Mezzocannone 16, 80134 Naples, Italy;
| | - Emanuele U. Garzarella
- Department of Pharmacy, University of Naples Federico II, Via D. Montesano 49, 80131 Naples, Italy; (N.I.); (E.U.G.); (A.R.)
| | - Nina G. Dolinnaya
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia;
| | - Marianna G. Yakubovskaya
- N.N. Blokhin National Medical Research Center of Oncology, Ministry of Health, 115478 Moscow, Russia; (A.M.O.); (M.G.Y.)
| | - Bruno Pagano
- Department of Pharmacy, University of Naples Federico II, Via D. Montesano 49, 80131 Naples, Italy; (N.I.); (E.U.G.); (A.R.)
| | - Jussara Amato
- Department of Pharmacy, University of Naples Federico II, Via D. Montesano 49, 80131 Naples, Italy; (N.I.); (E.U.G.); (A.R.)
| | - Antonio Randazzo
- Department of Pharmacy, University of Naples Federico II, Via D. Montesano 49, 80131 Naples, Italy; (N.I.); (E.U.G.); (A.R.)
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39
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Cheng Y, Zhang Y, Gong Z, Zhang X, Li Y, Shi X, Pei Y, You H. High Mechanical Stability and Slow Unfolding Rates Are Prevalent in Parallel-Stranded DNA G-Quadruplexes. J Phys Chem Lett 2020; 11:7966-7971. [PMID: 32885976 DOI: 10.1021/acs.jpclett.0c02229] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Guanine-rich repeat sequences are known to adopt diverse G-quadruplex (G4) topologies. Determining the unfolding rates of individual G4 species is challenging due to the coexistence of multiple G4 conformations in a solution. Here, using single-molecule magnetic tweezers, we systematically measured the unfolding force distributions of 4 oncogene promoter G4s, 12 model sequences with two 1-nucleotide (nt) thymine loops that predominantly adopt parallel-stranded G4 structures, and 6 sequences forming multiple G4 structures. All parallel-stranded G4s reveal an unfolding force peak at 40-60 pN, which is associated with extremely slow unfolding rates on the order of 10-5-10-7 s-1. In contrast, nonparallel G4s and partially folded intermediate states reveal an unfolding force peak <40 pN. These results suggest a strong correlation between the parallel-stranded G4s folding topology and the slow unfolding rates and provide important insights into the mechanism that govern the stability and the transition kinetics of G4s.
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Affiliation(s)
- Yuanlei Cheng
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan, China
| | - Yashuo Zhang
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan, China
| | - Zhou Gong
- CAS Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, National Center for Magnetic Resonance at Wuhan, Wuhan Institute of Physics and Mathematics of the Chinese Academy of Sciences, 430071 Wuhan, China
| | - Xinghua Zhang
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, 430072 Wuhan, China
| | - Yutong Li
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan, China
| | - Xiangqian Shi
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan, China
| | - Yufeng Pei
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan, China
| | - Huijuan You
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan, China
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40
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Imperatore C, Varriale A, Rivieccio E, Pennacchio A, Staiano M, D’Auria S, Casertano M, Altucci C, Valadan M, Singh M, Menna M, Varra M. Spectroscopic Properties of Two 5'-(4-Dimethylamino)Azobenzene Conjugated G-Quadruplex Forming Oligonucleotides. Int J Mol Sci 2020; 21:ijms21197103. [PMID: 32993097 PMCID: PMC7582650 DOI: 10.3390/ijms21197103] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/10/2020] [Accepted: 09/24/2020] [Indexed: 12/12/2022] Open
Abstract
The synthesis of two 5′-end (4-dimethylamino)azobenzene conjugated G-quadruplex forming aptamers, the thrombin binding aptamer (TBA) and the HIV-1 integrase aptamer (T30695), was performed. Their structural behavior was investigated by means of UV, CD, fluorescence spectroscopy, and gel electrophoresis techniques in K+-containing buffers and water-ethanol blends. Particularly, we observed that the presence of the 5′-(4-dimethylamino)azobenzene moiety leads TBA to form multimers instead of the typical monomolecular chair-like G-quadruplex and almost hampers T30695 G-quadruplex monomers to dimerize. Fluorescence studies evidenced that both the conjugated G-quadruplexes possess unique fluorescence features when excited at wavelengths corresponding to the UV absorption of the conjugated moiety. Furthermore, a preliminary investigation of the trans-cis conversion of the dye incorporated at the 5′-end of TBA and T30695 showed that, unlike the free dye, in K+-containing water-ethanol-triethylamine blend the trans-to-cis conversion was almost undetectable by means of a standard UV spectrophotometer.
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Affiliation(s)
- Concetta Imperatore
- Department of Pharmacy, School of Medicine, University of Naples “Federico II”, Via D. Montesano 49, 80131 Naples, Italy; (C.I.); (E.R.); (M.C.); (M.M.)
| | - Antonio Varriale
- Institute of Food Sciences, National Research Council of Italy, via Roma 64, 83100 Avellino, Italy; (A.V.); (A.P.); (M.S.); (S.D.)
| | - Elisa Rivieccio
- Department of Pharmacy, School of Medicine, University of Naples “Federico II”, Via D. Montesano 49, 80131 Naples, Italy; (C.I.); (E.R.); (M.C.); (M.M.)
| | - Angela Pennacchio
- Institute of Food Sciences, National Research Council of Italy, via Roma 64, 83100 Avellino, Italy; (A.V.); (A.P.); (M.S.); (S.D.)
| | - Maria Staiano
- Institute of Food Sciences, National Research Council of Italy, via Roma 64, 83100 Avellino, Italy; (A.V.); (A.P.); (M.S.); (S.D.)
| | - Sabato D’Auria
- Institute of Food Sciences, National Research Council of Italy, via Roma 64, 83100 Avellino, Italy; (A.V.); (A.P.); (M.S.); (S.D.)
| | - Marcello Casertano
- Department of Pharmacy, School of Medicine, University of Naples “Federico II”, Via D. Montesano 49, 80131 Naples, Italy; (C.I.); (E.R.); (M.C.); (M.M.)
| | - Carlo Altucci
- Department of Physics “Ettore Pancini”, University of Naples Federico II, Via Cinthia, 21—Building 6, 80126 Naples, Italy; (C.A.); (M.V.); (M.S.)
| | - Mohammadhassan Valadan
- Department of Physics “Ettore Pancini”, University of Naples Federico II, Via Cinthia, 21—Building 6, 80126 Naples, Italy; (C.A.); (M.V.); (M.S.)
| | - Manjot Singh
- Department of Physics “Ettore Pancini”, University of Naples Federico II, Via Cinthia, 21—Building 6, 80126 Naples, Italy; (C.A.); (M.V.); (M.S.)
| | - Marialuisa Menna
- Department of Pharmacy, School of Medicine, University of Naples “Federico II”, Via D. Montesano 49, 80131 Naples, Italy; (C.I.); (E.R.); (M.C.); (M.M.)
| | - Michela Varra
- Department of Pharmacy, School of Medicine, University of Naples “Federico II”, Via D. Montesano 49, 80131 Naples, Italy; (C.I.); (E.R.); (M.C.); (M.M.)
- Correspondence: ; Tel.: +39-081-678540
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41
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Bednářová K, Vorlíčková M, Renčiuk D. Diversity of Parallel Guanine Quadruplexes Induced by Guanine Substitutions. Int J Mol Sci 2020; 21:E6123. [PMID: 32854410 PMCID: PMC7503932 DOI: 10.3390/ijms21176123] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 08/21/2020] [Accepted: 08/22/2020] [Indexed: 01/17/2023] Open
Abstract
Recently, we reported an inhibitory effect of guanine substitutions on the conformational switch from antiparallel to parallel quadruplexes (G4) induced by dehydrating agents. As a possible cause, we proposed a difference in the sensitivity of parallel and antiparallel quadruplexes to the guanine substitutions in the resulting thermodynamic stability. Reports on the influence of guanine substitutions on the biophysical properties of intramolecular parallel quadruplexes are rare. Moreover, such reports are often complicated by the multimerisation tendencies of parallel quadruplexes. To address this incomplete knowledge, we employed circular dichroism spectroscopy (CD), both as stopped-flow-assisted fast kinetics measurements and end-point measurements, accompanied by thermodynamic analyses, based on UV absorption melting profiles, and electrophoretic methods. We showed that parallel quadruplexes are significantly more sensitive towards guanine substitutions than antiparallel ones. Furthermore, guanine-substituted variants, which in principle might correspond to native genomic sequences, distinctly differ in their biophysical properties, indicating that the four guanines in each tetrad of parallel quadruplexes are not equal. In addition, we were able to distinguish by CD an intramolecular G4 from intermolecular ones resulting from multimerisation mediated by terminal tetrad association, but not from intermolecular G4s formed due to inter-strand Hoogsteen hydrogen bond formation. In conclusion, our study indicates significant variability in parallel quadruplex structures, otherwise disregarded without detailed experimental analysis.
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Affiliation(s)
| | | | - Daniel Renčiuk
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic; (K.B.); (M.V.)
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42
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Cheng Y, Cheng M, Hao J, Jia G, Monchaud D, Li C. The noncovalent dimerization of a G-quadruplex/hemin DNAzyme improves its biocatalytic properties. Chem Sci 2020; 11:8846-8853. [PMID: 34123138 PMCID: PMC8163442 DOI: 10.1039/d0sc02907f] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Accepted: 07/15/2020] [Indexed: 12/31/2022] Open
Abstract
While many protein enzymes exert their functions through multimerization, which improves both selectivity and activity, this has not yet been demonstrated for other naturally occurring catalysts. Here, we report a multimerization effect applied to catalytic DNAs (or DNAzymes) and demonstrate that the enzymatic efficiency of G-quadruplexes (GQs) in interaction with the hemin cofactor is remarkably enhanced by homodimerization. The resulting non-covalent dimeric GQ-DNAzyme system provides hemin with a structurally defined active site in which both the cofactor (hemin) and the oxidant (H2O2) are activated. This new biocatalytic system efficiently performs peroxidase- and peroxygenase-type biotransformations of a broad range of substrates, thus providing new perspectives for biotechnological application of GQs.
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Affiliation(s)
- Yu Cheng
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences Dalian 116023 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Mingpan Cheng
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences Dalian 116023 China
| | - Jingya Hao
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences Dalian 116023 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Guoqing Jia
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences Dalian 116023 China
| | - David Monchaud
- Institut de Chimie Moléculaire de l' Université de Bourgogne (ICMUB), CNRS UMR 6302, UBFC Dijon 21078 Dijon France
| | - Can Li
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences Dalian 116023 China
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43
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Smirnov IP, Kolganova NA, Surzhikov SA, Grechishnikova IV, Novikov RA, Timofeev EN. Folding topology, structural polymorphism, and dimerization of intramolecular DNA G-quadruplexes with inverted polarity strands and non-natural loops. Int J Biol Macromol 2020; 162:1972-1981. [PMID: 32800956 DOI: 10.1016/j.ijbiomac.2020.08.097] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 08/09/2020] [Accepted: 08/10/2020] [Indexed: 01/27/2023]
Abstract
Synthetically modified DNA G-quadruplexes (GQs) have great potential in the development of designer molecules for a wide range of applications. Identification of the role of various structural elements in the folding and final topology of artificial GQs is necessary to predict their secondary structure. We report here the results of spectroscopic and electrophoretic studies of GQ scaffolds formed by G-rich sequences comprising four G3-tracts of different polarity connected by either a single-nucleotide thymine loop or a non-natural tetraethyleneglycol loop. Depending on G-strand polarities, loop arrangement and the presence of extra 5'-base G-rich oligonucleotides form monomeric, dimeric, or multimeric species of different topologies. In most cases, oligonucleotides were able to fold into stable parallel or hybrid GQs. However, certain specific arrangements of loops and G-tracts resulted in a diverse mixture of low stable structures. Comparative analysis of topology, stability, and structural heterogeneity of different G-rich sequences suggests the important role of loop type and arrangement, G3-tract polarities, and the presence of 5'-capping residues in the outcome of the folding process. The results also imply that the formation of anti-parallel G-hairpin intermediates is a key event in major favourable folding pathways.
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Affiliation(s)
- Igor P Smirnov
- Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow 119435, Russia
| | - Natalia A Kolganova
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia
| | - Sergei A Surzhikov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia
| | - Irina V Grechishnikova
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia
| | - Roman A Novikov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia; Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991, Moscow, Russia
| | - Edward N Timofeev
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia.
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44
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Esposito V, Esposito F, Pepe A, Gomez Monterrey I, Tramontano E, Mayol L, Virgilio A, Galeone A. Probing the Importance of the G-Quadruplex Grooves for the Activity of the Anti-HIV-Integrase Aptamer T30923. Int J Mol Sci 2020; 21:ijms21165637. [PMID: 32781637 PMCID: PMC7460552 DOI: 10.3390/ijms21165637] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 07/28/2020] [Accepted: 08/03/2020] [Indexed: 02/07/2023] Open
Abstract
In this paper, we report studies concerning four variants of the G-quadruplex forming anti-HIV-integrase aptamer T30923, in which specific 2′-deoxyguanosines have been singly replaced by 8-methyl-2′-deoxyguanosine residues, with the aim to exploit the methyl group positioned in the G-quadruplex grooves as a steric probe to investigate the interaction aptamer/target. Although, the various modified aptamers differ in the localization of the methyl group, NMR, circular dichroism (CD), electrophoretic and molecular modeling data suggest that all of them preserve the ability to fold in a stable dimeric parallel G-quadruplex complex resembling that of their natural counterpart T30923. However, the biological data have shown that the T30923 variants are characterized by different efficiencies in inhibiting the HIV-integrase, thus suggesting the involvement of the G-quadruplex grooves in the aptamer/target interaction.
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Affiliation(s)
- Veronica Esposito
- Department of Pharmacy, University of Naples Federico II, 80131 Napoli, Italy; (V.E.); (I.G.M.); (L.M.)
| | - Francesca Esposito
- Department of Life and Environmental Sciences, University of Cagliari, Cittadella Universitaria SS554, 09045 Monserrato (CA), Italy; (F.E.); (E.T.)
| | - Antonietta Pepe
- Department of Science, University of Basilicata, 85100 Potenza, Italy;
| | - Isabel Gomez Monterrey
- Department of Pharmacy, University of Naples Federico II, 80131 Napoli, Italy; (V.E.); (I.G.M.); (L.M.)
| | - Enzo Tramontano
- Department of Life and Environmental Sciences, University of Cagliari, Cittadella Universitaria SS554, 09045 Monserrato (CA), Italy; (F.E.); (E.T.)
| | - Luciano Mayol
- Department of Pharmacy, University of Naples Federico II, 80131 Napoli, Italy; (V.E.); (I.G.M.); (L.M.)
| | - Antonella Virgilio
- Department of Pharmacy, University of Naples Federico II, 80131 Napoli, Italy; (V.E.); (I.G.M.); (L.M.)
- Correspondence: (A.V.); (A.G.)
| | - Aldo Galeone
- Department of Pharmacy, University of Naples Federico II, 80131 Napoli, Italy; (V.E.); (I.G.M.); (L.M.)
- Correspondence: (A.V.); (A.G.)
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45
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Cao Y, Li W, Gao T, Ding P, Pei R. One Terminal Guanosine Flip of Intramolecular Parallel G-Quadruplex: Catalytic Enhancement of G-Quadruplex/Hemin DNAzymes. Chemistry 2020; 26:8631-8638. [PMID: 32428287 DOI: 10.1002/chem.202001462] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 05/13/2020] [Indexed: 11/09/2022]
Abstract
Numerous studies have shown compelling evidence that incorporation of an inversion of polarity site (IPS) in G-rich sequences can affect the topological and structural characteristics of G-quadruplexes (G4s). Herein, the influence of IPS on the formation of a previously studied intramolecular parallel G4 of d(G3 TG3 TG3 TG3 ) (TTT) and its stacked higher-order structures is explored. Insertion of 3'-3' or 5'-5' IPS did not change the parallel folding pattern of TTT. However, both the species and position of the IPS in TTT have a significant impact on the G4 stability and end-stacking through the alteration of G4-G4 interfaces properties. The data demonstrate that one base flip in each terminal G-tetrad can stabilize parallel G4s and facilitate intermolecular packing of monomeric G4s. Such modifications can also enhance the fluorescence and enzymatic performances by promoting interactions between parallel G4s with N-methyl mesoporphyrin IX (NMM) and hemin, respectively.
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Affiliation(s)
- Yanwei Cao
- CAS Key Laboratory of Nano-Bio Interface, Division of Nanobiomedicine, Suzhou Institute of Nano-Tech and Nano-Bionic, Chinese Academy of Sciences, Suzhou, 215123, P. R. China
| | - Wenjing Li
- CAS Key Laboratory of Nano-Bio Interface, Division of Nanobiomedicine, Suzhou Institute of Nano-Tech and Nano-Bionic, Chinese Academy of Sciences, Suzhou, 215123, P. R. China
| | - Tian Gao
- CAS Key Laboratory of Nano-Bio Interface, Division of Nanobiomedicine, Suzhou Institute of Nano-Tech and Nano-Bionic, Chinese Academy of Sciences, Suzhou, 215123, P. R. China
| | - Pi Ding
- CAS Key Laboratory of Nano-Bio Interface, Division of Nanobiomedicine, Suzhou Institute of Nano-Tech and Nano-Bionic, Chinese Academy of Sciences, Suzhou, 215123, P. R. China
| | - Renjun Pei
- CAS Key Laboratory of Nano-Bio Interface, Division of Nanobiomedicine, Suzhou Institute of Nano-Tech and Nano-Bionic, Chinese Academy of Sciences, Suzhou, 215123, P. R. China
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46
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Monsen RC, DeLeeuw L, Dean WL, Gray RD, Sabo T, Chakravarthy S, Chaires JB, Trent JO. The hTERT core promoter forms three parallel G-quadruplexes. Nucleic Acids Res 2020; 48:5720-5734. [PMID: 32083666 PMCID: PMC7261196 DOI: 10.1093/nar/gkaa107] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 02/06/2020] [Accepted: 02/17/2020] [Indexed: 12/13/2022] Open
Abstract
The structure of the 68 nt sequence with G-quadruplex forming potential within the hTERT promoter is disputed. One model features a structure with three stacked parallel G-quadruplex units, while another features an unusual duplex hairpin structure adjoined to two stacked parallel and antiparallel quadruplexes. We report here the results of an integrated structural biology study designed to distinguish between these possibilities. As part of our study, we designed a sequence with an optimized hairpin structure and show that its biophysical and biochemical properties are inconsistent with the structure formed by the hTERT wild-type sequence. By using circular dichroism, thermal denaturation, nuclear magnetic resonance spectroscopy, analytical ultracentrifugation, small-angle X-ray scattering, molecular dynamics simulations and a DNase I cleavage assay we found that the wild type hTERT core promoter folds into a stacked, three-parallel G-quadruplex structure. The hairpin structure is inconsistent with all of our experimental data obtained with the wild-type sequence. All-atom models for both structures were constructed using molecular dynamics simulations. These models accurately predicted the experimental hydrodynamic properties measured for each structure. We found with certainty that the wild-type hTERT promoter sequence does not form a hairpin structure in solution, but rather folds into a compact stacked three-G-quadruplex conformation.
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Affiliation(s)
- Robert C Monsen
- Department of Biochemistry & Molecular Genetics, University of Louisville, Louisville, KY 40202, USA
| | - Lynn DeLeeuw
- James Graham Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - William L Dean
- James Graham Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - Robert D Gray
- James Graham Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - T Michael Sabo
- Department of Biochemistry & Molecular Genetics, University of Louisville, Louisville, KY 40202, USA
- James Graham Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
- Department of Medicine, University of Louisville, Louisville, KY 40202, USA
| | - Srinivas Chakravarthy
- The Biophysics Collaborative Access Team (BioCAT), Department of Biological Chemical and Physical Sciences, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Jonathan B Chaires
- Department of Biochemistry & Molecular Genetics, University of Louisville, Louisville, KY 40202, USA
- James Graham Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
- Department of Medicine, University of Louisville, Louisville, KY 40202, USA
| | - John O Trent
- Department of Biochemistry & Molecular Genetics, University of Louisville, Louisville, KY 40202, USA
- James Graham Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
- Department of Medicine, University of Louisville, Louisville, KY 40202, USA
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47
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Binas O, Bessi I, Schwalbe H. Structure Validation of G-Rich RNAs in Noncoding Regions of the Human Genome. Chembiochem 2020; 21:1656-1663. [PMID: 31943589 PMCID: PMC7318348 DOI: 10.1002/cbic.201900696] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Indexed: 12/22/2022]
Abstract
We present the rapid biophysical characterization of six previously reported putative G-quadruplex-forming RNAs from the 5'-untranslated region (5'-UTR) of silvestrol-sensitive transcripts for investigation of their secondary structures. By NMR and CD spectroscopic analysis, we found that only a single sequence-[AGG]2 [CGG]2 C-folds into a single well-defined G-quadruplex structure. Sequences with longer poly-G strands form unspecific aggregates, whereas CGG-repeat-containing sequences exhibit a temperature-dependent equilibrium between a hairpin and a G-quadruplex structure. The applied experimental strategy is fast and provides robust readout for G-quadruplex-forming capacities of RNA oligomers.
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Affiliation(s)
- Oliver Binas
- Institute for Organic Chemistry and Chemical BiologyGoethe University FrankfurtMax-von-Laue Strasse 760438FrankfurtGermany
| | - Irene Bessi
- Institute for Organic and Biomolecular ChemistryJulius Maximilians University WürzburgAm Hubland97074WürzburgGermany
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical BiologyGoethe University FrankfurtMax-von-Laue Strasse 760438FrankfurtGermany
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48
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Roach RJ, Garavís M, González C, Jameson GB, Filichev VV, Hale TK. Heterochromatin protein 1α interacts with parallel RNA and DNA G-quadruplexes. Nucleic Acids Res 2020; 48:682-693. [PMID: 31799602 PMCID: PMC6954420 DOI: 10.1093/nar/gkz1138] [Citation(s) in RCA: 207] [Impact Index Per Article: 51.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 11/19/2019] [Accepted: 11/25/2019] [Indexed: 02/06/2023] Open
Abstract
The eukaryotic genome is functionally organized into domains of transcriptionally active euchromatin and domains of highly compact transcriptionally silent heterochromatin. Heterochromatin is constitutively assembled at repetitive elements that include the telomeres and centromeres. The histone code model proposes that HP1α forms and maintains these domains of heterochromatin through the interaction of its chromodomain with trimethylated lysine 9 of histone 3, although this interaction is not the sole determinant. We show here that the unstructured hinge domain, necessary for the targeting of HP1α to constitutive heterochromatin, recognizes parallel G-quadruplex (G4) assemblies formed by the TElomeric Repeat-containing RNA (TERRA) transcribed from the telomere. This provides a mechanism by which TERRA can lead to the enrichment of HP1α at telomeres to maintain heterochromatin. Furthermore, we show that HP1α binds with a faster association rate to DNA G4s of parallel topology compared to antiparallel G4s that bind slowly or not at all. Such G4–DNAs are found in the regulatory regions of several oncogenes. This implicates specific non-canonical nucleic acid structures as determinants of HP1α function and thus RNA and DNA G4s need to be considered as contributors to chromatin domain organization and the epigenome.
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Affiliation(s)
- Ruby J Roach
- School of Fundamental Sciences, Massey University, Private Bag 11-222, Palmerston North 4442, New Zealand
| | - Miguel Garavís
- Instituto de Química Física 'Rocasolano', CSIC, Serrano 119, 28006 Madrid, Spain
| | - Carlos González
- Instituto de Química Física 'Rocasolano', CSIC, Serrano 119, 28006 Madrid, Spain
| | - Geoffrey B Jameson
- School of Fundamental Sciences, Massey University, Private Bag 11-222, Palmerston North 4442, New Zealand.,Maurice Wilkins Centre, Private Bag 92019, Auckland, New Zealand
| | - Vyacheslav V Filichev
- School of Fundamental Sciences, Massey University, Private Bag 11-222, Palmerston North 4442, New Zealand.,Maurice Wilkins Centre, Private Bag 92019, Auckland, New Zealand
| | - Tracy K Hale
- School of Fundamental Sciences, Massey University, Private Bag 11-222, Palmerston North 4442, New Zealand.,Maurice Wilkins Centre, Private Bag 92019, Auckland, New Zealand
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Pavc D, Wang B, Spindler L, Drevenšek-Olenik I, Plavec J, Šket P. GC ends control topology of DNA G-quadruplexes and their cation-dependent assembly. Nucleic Acids Res 2020; 48:2749-2761. [PMID: 31996902 PMCID: PMC7049726 DOI: 10.1093/nar/gkaa058] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 01/17/2020] [Accepted: 01/21/2020] [Indexed: 01/22/2023] Open
Abstract
GCn and GCnCG, where n = (G2AG4AG2), fold into well-defined, dimeric G-quadruplexes with unprecedented folding topologies in the presence of Na+ ions as revealed by nuclear magnetic resonance spectroscopy. Both G-quadruplexes exhibit unique combination of structural elements among which are two G-quartets, A(GGGG)A hexad and GCGC-quartet. Detailed structural characterization uncovered the crucial role of 5'-GC ends in formation of GCn and GCnCG G-quadruplexes. Folding in the presence of 15NH4+ and K+ ions leads to 3'-3' stacking of terminal G-quartets of GCn G-quadruplexes, while 3'-GC overhangs in GCnCG prevent dimerization. Results of the present study expand repertoire of possible G-quadruplex structures. This knowledge will be useful in DNA sequence design for nanotechnological applications that may require specific folding topology and multimerization properties.
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Affiliation(s)
- Daša Pavc
- Slovenian NMR Center, National Institute of Chemistry, 1000 Ljubljana, Slovenia
- University of Ljubljana, Faculty of Chemistry and Chemical Technology, 1000 Ljubljana, Slovenia
| | - Baifan Wang
- Slovenian NMR Center, National Institute of Chemistry, 1000 Ljubljana, Slovenia
| | - Lea Spindler
- University of Maribor, Faculty of Mechanical Engineering, 2000 Maribor, Slovenia
- Department of Complex Matter, Jozef Stefan Institute, 1000 Ljubljana, Slovenia
| | - Irena Drevenšek-Olenik
- Department of Complex Matter, Jozef Stefan Institute, 1000 Ljubljana, Slovenia
- University of Ljubljana, Faculty of Mathematics and Physics, 1000 Ljubljana, Slovenia
| | - Janez Plavec
- Slovenian NMR Center, National Institute of Chemistry, 1000 Ljubljana, Slovenia
- University of Ljubljana, Faculty of Chemistry and Chemical Technology, 1000 Ljubljana, Slovenia
- EN-FIST Center of Excellence, 1000 Ljubljana, Slovenia
| | - Primož Šket
- Slovenian NMR Center, National Institute of Chemistry, 1000 Ljubljana, Slovenia
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In-Gel Probing Polymorphic Structures of G-Quadruplexes Derived from c-Myc Promoter. CHINESE JOURNAL OF ANALYTICAL CHEMISTRY 2020. [DOI: 10.1016/s1872-2040(20)60002-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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