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Zhang Y, Cheng Y, Luo Q, Wu T, Huo J, Yin M, Peng H, Xiao Y, Tong Q, You H. Distinguishing G-Quadruplexes Stabilizer and Chaperone for c- MYC Promoter G-Quadruplexes through Single-Molecule Manipulation. J Am Chem Soc 2024; 146:3689-3699. [PMID: 38296825 DOI: 10.1021/jacs.3c09074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2024]
Abstract
G-quadruplex (G4) selective stabilizing ligands can regulate c-MYC gene expression, but the kinetic basis remains unclear. Determining the effects of ligands on c-MYC promoter G4s' folding/unfolding kinetics is challenging due to the polymorphic nature of G4s and the high energy barrier to unfold c-MYC promoter G4s. Here, we used single-molecule magnetic tweezers to manipulate a duplex hairpin containing a c-MYC promoter sequence to mimic the transiently denatured duplex during transcription. We measured the effects of six commonly used G4s binding ligands on the competition between quadruplex and duplex structures, as well as the folding/unfolding kinetics of G4s. Our results revealed two distinct roles for G4s selective stabilization: CX-5461 is mainly acting as c-MYC G4s stabilizer, reducing the unfolding rate (ku) of c-MYC G4s, whereas PDS and 360A also act as G4s chaperone, accelerating the folding rates (kf) of c-MYC G4s. qRT-PCR results obtained from CA46 and Raji cell lines demonstrated that G4s stabilizing ligands can downregulate c-MYC expression, while G4s stabilizer CX-5461 exhibited the strongest c-MYC gene suppression. These results shed light on the potential of manipulating G4s' folding/unfolding kinetics by ligands for precise regulation of promoter G4-associated biological activities.
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Affiliation(s)
- Yashuo Zhang
- Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Yuanlei Cheng
- Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
- Department of Pharmacy, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430014, China
| | - Qun Luo
- Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Tongbo Wu
- Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Junfeng Huo
- Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Meng Yin
- Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Hui Peng
- Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Yang Xiao
- Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Qingyi Tong
- Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Huijuan You
- Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
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2
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Kim H, Kim E, Pak Y. Computational Probing of the Folding Mechanism of Human Telomeric G-Quadruplex DNA. J Chem Inf Model 2023; 63:6366-6375. [PMID: 37782649 DOI: 10.1021/acs.jcim.3c01257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
The human telomeric (htel) sequences in the terminal regions of human telomeres form diverse G-quadruplex (GQ) structures. Despite much experimental efforts to elucidate the folding pathways of htel GQ, no comprehensive model of htel GQ folding has been presented. Here, we describe folding pathways of the htel GQ determined by state-of-the-art enhanced sampling molecular dynamics simulation at the all-atom level. Briefly, GQ folding is initiated by the formation of a single-hairpin and then followed by the formation of double-hairpins, which then branch via distinct folding pathways to produce different GQ topologies (antiparallel chair, antiparallel basket, hybrids 1 and 2, and parallel propeller). In addition to these double-hairpin states, three-triad and two-tetrad structures in antiparallel backbone alignment serve as key intermediates that connect the GQ folding and transition between two different GQs.
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Affiliation(s)
- Hyeonjun Kim
- Department of Chemistry and Institute of Functional Materials, Pusan National University, Busan 46241, South Korea
| | - Eunae Kim
- College of Pharmacy, Chosun University, Gwangju 61452, South Korea
| | - Youngshang Pak
- Department of Chemistry and Institute of Functional Materials, Pusan National University, Busan 46241, South Korea
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3
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Libera V, Ripanti F, Petrillo C, Sacchetti F, Ramos-Soriano J, Galan MC, Schirò G, Paciaroni A, Comez L. Stability of Human Telomeric G-Quadruplexes Complexed with Photosensitive Ligands and Irradiated with Visible Light. Int J Mol Sci 2023; 24:ijms24109090. [PMID: 37240437 DOI: 10.3390/ijms24109090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 05/16/2023] [Accepted: 05/19/2023] [Indexed: 05/28/2023] Open
Abstract
Guanine-rich DNA sequences can fold into non-canonical nucleic acid structures called G-quadruplexes (G4s). These nanostructures have strong implications in many fields, from medical science to bottom-up nanotechnologies. As a result, ligands interacting with G4s have attracted great attention as candidates in medical therapies, molecular probe applications, and biosensing. In recent years, the use of G4-ligand complexes as photopharmacological targets has shown significant promise for developing novel therapeutic strategies and nanodevices. Here, we studied the possibility of manipulating the secondary structure of a human telomeric G4 sequence through the interaction with two photosensitive ligands, DTE and TMPyP4, whose response to visible light is different. The effect of these two ligands on G4 thermal unfolding was also considered, revealing the occurrence of peculiar multi-step melting pathways and the different attitudes of the two molecules on the quadruplex stabilization.
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Affiliation(s)
- Valeria Libera
- Department of Physics and Geology, University of Perugia, Via Alessandro Pascoli, 06123 Perugia, Italy
- Istituto Officina dei Materiali-IOM, National Research Council-CNR, Via Alessandro Pascoli, 06123 Perugia, Italy
| | - Francesca Ripanti
- Department of Physics and Geology, University of Perugia, Via Alessandro Pascoli, 06123 Perugia, Italy
| | - Caterina Petrillo
- Department of Physics and Geology, University of Perugia, Via Alessandro Pascoli, 06123 Perugia, Italy
| | - Francesco Sacchetti
- Department of Physics and Geology, University of Perugia, Via Alessandro Pascoli, 06123 Perugia, Italy
| | - Javier Ramos-Soriano
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
| | - Maria Carmen Galan
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
| | - Giorgio Schirò
- CNRS, CEA, IBS, c/o University Grenoble Alpes, 38400 Grenoble, France
| | - Alessandro Paciaroni
- Department of Physics and Geology, University of Perugia, Via Alessandro Pascoli, 06123 Perugia, Italy
| | - Lucia Comez
- Istituto Officina dei Materiali-IOM, National Research Council-CNR, Via Alessandro Pascoli, 06123 Perugia, Italy
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4
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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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5
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Stein M, Hile SE, Weissensteiner MH, Lee M, Zhang S, Kejnovský E, Kejnovská I, Makova KD, Eckert KA. Variation in G-quadruplex sequence and topology differentially impacts human DNA polymerase fidelity. DNA Repair (Amst) 2022; 119:103402. [PMID: 36116264 PMCID: PMC9798401 DOI: 10.1016/j.dnarep.2022.103402] [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: 04/22/2022] [Revised: 08/12/2022] [Accepted: 09/02/2022] [Indexed: 12/31/2022]
Abstract
G-quadruplexes (G4s), a type of non-B DNA, play important roles in a wide range of molecular processes, including replication, transcription, and translation. Genome integrity relies on efficient and accurate DNA synthesis, and is compromised by various stressors, to which non-B DNA structures such as G4s can be particularly vulnerable. However, the impact of G4 structures on DNA polymerase fidelity is largely unknown. Using an in vitro forward mutation assay, we investigated the fidelity of human DNA polymerases delta (δ4, four-subunit), eta (η), and kappa (κ) during synthesis of G4 motifs representing those in the human genome. The motifs differ in sequence, topology, and stability, features that may affect DNA polymerase errors. Polymerase error rate hierarchy (δ4 < κ < η) is largely maintained during G4 synthesis. Importantly, we observed unique polymerase error signatures during synthesis of VEGF G4 motifs, stable G4s which form parallel topologies. These statistically significant errors occurred within, immediately flanking, and encompassing the G4 motif. For pol δ4, the errors were deletions, insertions and complex errors within the G4 or encompassing the G4 motif and surrounding sequence. For pol η, the errors occurred in 3' sequences flanking the G4 motif. For pol κ, the errors were frameshift mutations within G-tracts of the G4. Because these error signatures were not observed during synthesis of an antiparallel G4 and, to a lesser extent, a hybrid G4, we suggest that G4 topology and/or stability could influence polymerase fidelity. Using in silico analyses, we show that most polymerase errors are predicted to have minimal effects on predicted G4 stability. Our results provide a unique view of G4s not previously elucidated, showing that G4 motif heterogeneity differentially influences polymerase fidelity within the motif and flanking sequences. Thus, our study advances the understanding of how DNA polymerase errors contribute to G4 mutagenesis.
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Affiliation(s)
- MaryElizabeth Stein
- Department of Pathology, The Jake Gittlen Laboratories for Cancer Research, Penn State University College of Medicine, Hershey, PA, USA
| | - Suzanne E Hile
- Department of Pathology, The Jake Gittlen Laboratories for Cancer Research, Penn State University College of Medicine, Hershey, PA, USA
| | | | - Marietta Lee
- Department of Biochemistry & Molecular Biology, New York Medical College, Valhalla, NY, USA
| | - Sufang Zhang
- Department of Biochemistry & Molecular Biology, New York Medical College, Valhalla, NY, USA
| | - Eduard Kejnovský
- Department of Plant Developmental Genetics, Institute of Biophysics of the Czech Academy of Sciences, Brno, Czech Republic
| | - Iva Kejnovská
- Department of Biophysics of Nucleic Acids, Institute of Biophysics of the Czech Academy of Sciences, Brno, Czech Republic
| | - Kateryna D Makova
- Department of Biology, Penn State University Eberly College of Science, University Park, PA, USA
| | - Kristin A Eckert
- Department of Pathology, The Jake Gittlen Laboratories for Cancer Research, Penn State University College of Medicine, Hershey, PA, USA.
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6
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Liu L, Zhu L, Tong H, Su C, Wells JW, Chalikian TV. Distribution of Conformational States Adopted by DNA from the Promoter Regions of the VEGF and Bcl-2 Oncogenes. J Phys Chem B 2022; 126:6654-6670. [PMID: 36001297 DOI: 10.1021/acs.jpcb.2c04304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We employed a previously described procedure, based on circular dichroism (CD) spectroscopy, to quantify the distribution of conformational states adopted by equimolar mixtures of complementary G-rich and C-rich DNA strands from the promoter regions of the VEGF and Bcl-2 oncogenes. Spectra were recorded at different pHs, concentrations of KCl, and temperatures. The temperature dependences of the fractional populations of the duplex, G-quadruplex, i-motif, and coiled conformations of each promoter were then analyzed within the framework of a thermodynamic model to obtain the enthalpy and melting temperature of each folded-to-unfolded transition involved in the equilibrium. A comparison of the conformational data on the VEGF and Bcl-2 DNA with similar results on the c-MYC DNA, which we reported previously, reveals that the distribution of conformational states depends on the specific DNA sequence and is modulated by environmental factors. Under the physiological conditions of room temperature, neutral pH, and elevated concentrations of potassium ions, the duplex conformation coexists with the G-quadruplex conformation in proportions that depend on the sequence. This observed conformational diversity has biological implications, and it further supports our previously proposed thermodynamic hypothesis of gene regulation. In that hypothesis, a specific distribution of duplex and tetraplex conformations in a promoter region is fine-tuned to maintain the healthy level of gene expression. Any deviation from a healthy distribution of conformational states may result in pathology stemming from up- or downregulation of the gene.
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Affiliation(s)
- Lutan Liu
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
| | - Legeng Zhu
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
| | - Haoyuan Tong
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
| | - Chongyu Su
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
| | - James W Wells
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
| | - Tigran V Chalikian
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
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7
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Bhogadia M, Stone B, Del Villar Guerra R, Muskett FW, Ghosh S, Taladriz-Sender A, Burley GA, Eperon IC, Hudson AJ, Dominguez C. Biophysical characterisation of the Bcl-x pre-mRNA and binding specificity of the ellipticine derivative GQC-05: Implication for alternative splicing regulation. Front Mol Biosci 2022; 9:943105. [PMID: 36060245 PMCID: PMC9428248 DOI: 10.3389/fmolb.2022.943105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 07/18/2022] [Indexed: 11/21/2022] Open
Abstract
The BCL2L1 gene expresses two isoforms of Bcl-x protein via the use of either of two alternative 5′ splice sites (5′ss) in exon 2. These proteins have antagonistic actions, Bcl-XL being anti-apoptotic and Bcl-XS pro-apoptotic. In a number of cancers the Bcl-XL isoform is over-expressed, resulting in cancer cell survival and growth, so switching splicing to the Xs isoform could have therapeutic benefits. We have previously proposed that a putative G-quadruplex (G4) exists downstream of the XS 5′ss and shown that the ellipticine derivative GQC-05, a previously identified DNA G4-specific ligand, induces an increase in the XS/XL ratio both in vitro and in cells. Here, we demonstrate that this G4 forms in vitro and that the structure is stabilised in the presence of GQC-05. We also show that GQC-05 binds RNA non-specifically in buffer conditions, but selectively to the Bcl-x G4 in the presence of nuclear extract, highlighting the limitations of biophysical measurements taken outside of a functional environment. We also demonstrate that GQC-05 is able to shift the equilibrium between competing G4 and duplex structures towards the G4 conformation, leading to an increase in accessibility of the XS 5′ss, supporting our previous model on the mechanism of action of GQC-05.
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Affiliation(s)
- Mohammed Bhogadia
- The Leicester Institute of Structural and Chemical Biology, Department of Molecular and Cell Biology, University of Leicester, Leicester, United Kingdom
| | - Beth Stone
- The Leicester Institute of Structural and Chemical Biology, Department of Chemistry, University of Leicester, Leicester, United Kingdom
| | - Rafael Del Villar Guerra
- The Leicester Institute of Structural and Chemical Biology, Department of Molecular and Cell Biology, University of Leicester, Leicester, United Kingdom
| | - Frederick W. Muskett
- The Leicester Institute of Structural and Chemical Biology, Department of Molecular and Cell Biology, University of Leicester, Leicester, United Kingdom
| | - Sudipta Ghosh
- The Leicester Institute of Structural and Chemical Biology, Department of Molecular and Cell Biology, University of Leicester, Leicester, United Kingdom
| | - Andrea Taladriz-Sender
- Department of Pure Applied Chemistry, University of Strathclyde, Glasgow, United Kingdom
| | - Glenn A. Burley
- Department of Pure Applied Chemistry, University of Strathclyde, Glasgow, United Kingdom
| | - Ian C. Eperon
- The Leicester Institute of Structural and Chemical Biology, Department of Molecular and Cell Biology, University of Leicester, Leicester, United Kingdom
- *Correspondence: Ian C. Eperon, ; Andrew J. Hudson, ; Cyril Dominguez,
| | - Andrew J. Hudson
- The Leicester Institute of Structural and Chemical Biology, Department of Chemistry, University of Leicester, Leicester, United Kingdom
- *Correspondence: Ian C. Eperon, ; Andrew J. Hudson, ; Cyril Dominguez,
| | - Cyril Dominguez
- The Leicester Institute of Structural and Chemical Biology, Department of Molecular and Cell Biology, University of Leicester, Leicester, United Kingdom
- *Correspondence: Ian C. Eperon, ; Andrew J. Hudson, ; Cyril Dominguez,
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8
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Luo Y, Verga D, Mergny JL. Iso-FRET: an isothermal competition assay to analyze quadruplex formation in vitro. Nucleic Acids Res 2022; 50:e93. [PMID: 35670668 PMCID: PMC9458428 DOI: 10.1093/nar/gkac465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 04/26/2022] [Accepted: 05/16/2022] [Indexed: 11/23/2022] Open
Abstract
Algorithms have been widely used to predict G-quadruplexes (G4s)-prone sequences. However, an experimental validation of these predictions is generally required. We previously reported a high-throughput technique to evidence G4 formation in vitro called FRET-MC. This method, while convenient and reproducible, has one known weakness: its inability to pin point G4 motifs of low thermal stability. As such quadruplexes may still be biologically relevant if formed at physiological temperature, we wanted to develop an independent assay to overcome this limitation. To this aim, we introduced an isothermal version of the competition assay, called iso-FRET, based on a duplex-quadruplex competition and a well-characterized bis-quinolinium G4 ligand, PhenDC3. G4-forming competitors act as decoys for PhenDC3, lowering its ability to stabilize the G4-forming motif reporter oligonucleotide conjugated to a fluorescence quencher (37Q). The decrease in available G4 ligand concentration restores the ability of 37Q to hybridize to its FAM-labeled short complementary C-rich strand (F22), leading to a decrease in fluorescence signal. In contrast, when no G4-forming competitor is present, PhenDC3 remains available to stabilize the 37Q quadruplex, preventing the formation of the F22 + 37Q complex. Iso-FRET was first applied to a reference panel of 70 sequences, and then used to investigate 23 different viral sequences.
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Affiliation(s)
- Yu Luo
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, CNRS, Inserm, Institut Polytechnique de Paris, 91128 Palaiseau, France.,CNRS UMR9187, INSERM U1196, Université Paris-Saclay, F-91405 Orsay, France
| | - Daniela Verga
- CNRS UMR9187, INSERM U1196, Université Paris-Saclay, F-91405 Orsay, France.,CNRS UMR9187, INSERM U1196, Institut Curie, PSL Research University, F-91405 Orsay, France
| | - Jean-Louis Mergny
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, CNRS, Inserm, Institut Polytechnique de Paris, 91128 Palaiseau, France
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9
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Libera V, Bianchi F, Rossi B, D’Amico F, Masciovecchio C, Petrillo C, Sacchetti F, Paciaroni A, Comez L. Solvent Vibrations as a Proxy of the Telomere G-Quadruplex Rearrangements across Thermal Unfolding. Int J Mol Sci 2022; 23:ijms23095123. [PMID: 35563512 PMCID: PMC9100830 DOI: 10.3390/ijms23095123] [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: 03/31/2022] [Revised: 04/26/2022] [Accepted: 04/29/2022] [Indexed: 11/16/2022] Open
Abstract
G-quadruplexes (G4s) are noncanonical forms of DNA involved in many key genome functions. Here, we exploited UV Resonance Raman scattering to simultaneously explore the vibrational behavior of a human telomeric G4 (Tel22) and its aqueous solvent as the biomolecule underwent thermal melting. We found that the OH stretching band, related to the local hydrogen-bonded network of a water molecule, was in strict relation with the vibrational features of the G4 structure as a function of temperature. In particular, the modifications to the tetrahedral ordering of the water network were strongly coupled to the DNA rearrangements, showing changes in temperature that mirrored the multi-step melting process of Tel22. The comparison between circular dichroism and Raman results supported this view. The present findings provide novel insights into the impact of the molecular environment on G4 conformation. Improving current knowledge on the solvent structural properties will also contribute to a better understanding of the role played by water arrangement in the complexation of G4s with ligands.
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Affiliation(s)
- Valeria Libera
- Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, 06123 Perugia, Italy; (V.L.); (F.B.); (C.P.); (F.S.)
- IOM-CNR c/o Department of Physics and Geology, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Federico Bianchi
- Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, 06123 Perugia, Italy; (V.L.); (F.B.); (C.P.); (F.S.)
| | - Barbara Rossi
- Elettra Sincrotrone Trieste, S.S. 14 Km 163.5, 34012 Trieste, Italy; (B.R.); (F.D.); (C.M.)
| | - Francesco D’Amico
- Elettra Sincrotrone Trieste, S.S. 14 Km 163.5, 34012 Trieste, Italy; (B.R.); (F.D.); (C.M.)
| | - Claudio Masciovecchio
- Elettra Sincrotrone Trieste, S.S. 14 Km 163.5, 34012 Trieste, Italy; (B.R.); (F.D.); (C.M.)
| | - Caterina Petrillo
- Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, 06123 Perugia, Italy; (V.L.); (F.B.); (C.P.); (F.S.)
| | - Francesco Sacchetti
- Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, 06123 Perugia, Italy; (V.L.); (F.B.); (C.P.); (F.S.)
| | - Alessandro Paciaroni
- Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, 06123 Perugia, Italy; (V.L.); (F.B.); (C.P.); (F.S.)
- Correspondence: (A.P.); (L.C.)
| | - Lucia Comez
- IOM-CNR c/o Department of Physics and Geology, Università degli Studi di Perugia, 06123 Perugia, Italy
- Correspondence: (A.P.); (L.C.)
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10
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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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11
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Grün JT, Schwalbe H. Folding dynamics of polymorphic G-quadruplex structures. Biopolymers 2021; 113:e23477. [PMID: 34664713 DOI: 10.1002/bip.23477] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 09/30/2021] [Accepted: 09/30/2021] [Indexed: 12/14/2022]
Abstract
G-quadruplexes (G4), found in numerous places within the human genome, are involved in essential processes of cell regulation. Chromosomal DNA G4s are involved for example, in replication and transcription as first steps of gene expression. Hence, they influence a plethora of downstream processes. G4s possess an intricate structure that differs from canonical B-form DNA. Identical DNA G4 sequences can adopt multiple long-lived conformations, a phenomenon known as G4 polymorphism. A detailed understanding of the molecular mechanisms that drive G4 folding is essential to understand their ambivalent regulatory roles. Disentangling the inherent dynamic and polymorphic nature of G4 structures thus is key to unravel their biological functions and make them amenable as molecular targets in novel therapeutic approaches. We here review recent experimental approaches to monitor G4 folding and discuss structural aspects for possible folding pathways. Substantial progress in the understanding of G4 folding within the recent years now allows drawing comprehensive models of the complex folding energy landscape of G4s that we herein evaluate based on computational and experimental evidence.
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Affiliation(s)
- J Tassilo Grün
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe-University, Frankfurt/M, Germany.,Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Frankfurt/M, Germany
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12
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Sato K, Martin-Pintado N, Post H, Altelaar M, Knipscheer P. Multistep mechanism of G-quadruplex resolution during DNA replication. SCIENCE ADVANCES 2021; 7:eabf8653. [PMID: 34559566 PMCID: PMC8462899 DOI: 10.1126/sciadv.abf8653] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
G-quadruplex (or G4) structures form in guanine-rich DNA sequences and threaten genome stability when not properly resolved. G4 unwinding occurs during S phase via an unknown mechanism. Using Xenopus egg extracts, we define a three-step G4 unwinding mechanism that acts during DNA replication. First, the replicative helicase composed of Cdc45, MCM2-7 and GINS (CMG) stalls at a leading strand G4 structure. Second, the DEAH-box helicase 36 (DHX36) mediates bypass of the CMG past the intact G4 structure, allowing approach of the leading strand to the G4. Third, G4 structure unwinding by the Fanconi anemia complementation group J helicase (FANCJ) enables DNA polymerase to synthesize past the G4 motif. A G4 on the lagging strand template does not stall CMG but still requires DNA replication for unwinding. DHX36 and FANCJ have partially redundant roles, conferring pathway robustness. This previously unknown genome maintenance pathway promotes faithful G4 replication, thereby avoiding genome instability.
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Affiliation(s)
- Koichi Sato
- Oncode Institute, Hubrecht Institute–KNAW and University Medical Center Utrecht, Uppsalalaan 8, Utrecht 3584 CT, Netherlands
| | - Nerea Martin-Pintado
- Oncode Institute, Hubrecht Institute–KNAW and University Medical Center Utrecht, Uppsalalaan 8, Utrecht 3584 CT, Netherlands
| | - Harm Post
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, Utrecht 3584 CH, Netherlands
| | - Maarten Altelaar
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, Utrecht 3584 CH, Netherlands
| | - Puck Knipscheer
- Oncode Institute, Hubrecht Institute–KNAW and University Medical Center Utrecht, Uppsalalaan 8, Utrecht 3584 CT, Netherlands
- Corresponding author.
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13
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Deiana M, Mosser M, Le Bahers T, Dumont E, Dudek M, Denis-Quanquin S, Sabouri N, Andraud C, Matczyszyn K, Monnereau C, Guy L. Light-induced in situ chemical activation of a fluorescent probe for monitoring intracellular G-quadruplex structures. NANOSCALE 2021; 13:13795-13808. [PMID: 34477654 DOI: 10.1039/d1nr02855c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Light-activated functional materials capable of remote control over duplex and G-quadruplex (G4) nucleic acids formation at the cellular level are still very rare. Herein, we report on the photoinduced macrocyclisation of a helicenoid quinoline derivative of binaphthol that selectively provides easy access to an unprecedented class of extended heteroaromatic structures with remarkable photophysical and DNA/RNA binding properties. Thus, while the native bisquinoline precursor shows no DNA binding activity, the new in situ photochemically generated probe features high association constants to DNA and RNA G4s. The latter inhibits DNA synthesis by selectively stabilizing G4 structures associated with oncogenic promoters and telomere repeat units. Finally, the light sensitive compound is capable of in cellulo photoconversion, localizes primarily in the G4-rich sites of cancer cells, competes with a well-known G4 binder and shows a clear nuclear co-localization with the quadruplex specific antibody BG4. This work provides a benchmark for the future design and development of a brand-new generation of light-activated target-selective G4-binders.
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Affiliation(s)
- Marco Deiana
- Department of Medical Biochemistry and Biophysics, Umeå University, 90187 Umeå, Sweden.
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14
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Libera V, Andreeva EA, Martel A, Thureau A, Longo M, Petrillo C, Paciaroni A, Schirò G, Comez L. Porphyrin Binding and Irradiation Promote G-Quadruplex DNA Dimeric Structure. J Phys Chem Lett 2021; 12:8096-8102. [PMID: 34406777 DOI: 10.1021/acs.jpclett.1c01840] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Nucleic acid sequences rich in guanines can organize into noncanonical DNA G-quadruplexes (G4s) of variable size. The design of small molecules stabilizing the structure of G4s is a rapidly growing area for the development of novel anticancer therapeutic strategies and bottom-up nanotechnologies. Among a multitude of binders, porphyrins are very attractive due to their light activation that can make them valuable conformational regulators of G4s. Here, a structure-based strategy, integrating complementary probes, is employed to study the interaction between TMPyP4 porphyrin and a 22-base human telomeric sequence (Tel22) before and after irradiation with blue light. Porphyrin binding is discovered to promote Tel22 dimerization, while light irradiation of the Tel22-TMPyP4 complex controls dimer fraction. Such a change in quaternary structure is found to be strictly correlated with modifications at the secondary structure level, thus providing an unprecedented link between the degree of dimerization and the underlying conformational changes in G4s.
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Affiliation(s)
- Valeria Libera
- Dipartimento di Fisica e Geologia, Università di Perugia, Via Pascoli, 06123 Perugia, Italy
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
- CNR-IOM c/o Dipartimento di Fisica e Geologia, Università di Perugia, Via Pascoli, 06123 Perugia, Italy
| | - Elena A Andreeva
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, F-38000 Grenoble, France
| | - Anne Martel
- Institut Laue-Langevin, 71 avenue des Martyrs, 38042 Grenoble Cedex 9, France
| | - Aurelien Thureau
- Swing Beamline, Synchrotron SOLEIL, 91192 Gif sur Yvette, France
| | - Marialucia Longo
- Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum, Lichtenbergstraße 1, 85748 Garching, Germany
| | - Caterina Petrillo
- Dipartimento di Fisica e Geologia, Università di Perugia, Via Pascoli, 06123 Perugia, Italy
| | - Alessandro Paciaroni
- Dipartimento di Fisica e Geologia, Università di Perugia, Via Pascoli, 06123 Perugia, Italy
| | - Giorgio Schirò
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, F-38000 Grenoble, France
| | - Lucia Comez
- CNR-IOM c/o Dipartimento di Fisica e Geologia, Università di Perugia, Via Pascoli, 06123 Perugia, Italy
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15
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Deiana M, Obi I, Andreasson M, Tamilselvi S, Chand K, Chorell E, Sabouri N. A Minimalistic Coumarin Turn-On Probe for Selective Recognition of Parallel G-Quadruplex DNA Structures. ACS Chem Biol 2021; 16:1365-1376. [PMID: 34328300 PMCID: PMC8397291 DOI: 10.1021/acschembio.1c00134] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
![]()
G-quadruplex (G4)
DNA structures are widespread in the human genome
and are implicated in biologically important processes such as telomere
maintenance, gene regulation, and DNA replication. Guanine-rich sequences
with potential to form G4 structures are prevalent in the promoter
regions of oncogenes, and G4 sites are now considered as attractive
targets for anticancer therapies. However, there are very few reports
of small “druglike” optical G4 reporters that are easily
accessible through one-step synthesis and that are capable of discriminating
between different G4 topologies. Here, we present a small water-soluble
light-up fluorescent probe that features a minimalistic amidinocoumarin-based
molecular scaffold that selectively targets parallel G4 structures
over antiparallel and non-G4 structures. We showed that this biocompatible
ligand is able to selectively stabilize the G4 template resulting
in slower DNA synthesis. By tracking individual DNA molecules, we
demonstrated that the G4-stabilizing ligand perturbs DNA replication
in cancer cells, resulting in decreased cell viability. Moreover,
the fast-cellular entry of the probe enabled detection of nucleolar
G4 structures in living cells. Finally, insights gained from the structure–activity
relationships of the probe suggest the basis for the recognition of
parallel G4s, opening up new avenues for the design of new biocompatible
G4-specific small molecules for G4-driven theranostic applications.
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Affiliation(s)
- Marco Deiana
- Department of Medical Biochemistry and Biophysics, Umeå University, 90187 Umeå, Sweden
| | - Ikenna Obi
- Department of Medical Biochemistry and Biophysics, Umeå University, 90187 Umeå, Sweden
| | - Måns Andreasson
- Department of Chemistry, Umeå University, 90187 Umeå, Sweden
| | - Shanmugam Tamilselvi
- Department of Medical Biochemistry and Biophysics, Umeå University, 90187 Umeå, Sweden
| | - Karam Chand
- Department of Chemistry, Umeå University, 90187 Umeå, Sweden
| | - Erik Chorell
- Department of Chemistry, Umeå University, 90187 Umeå, Sweden
| | - Nasim Sabouri
- Department of Medical Biochemistry and Biophysics, Umeå University, 90187 Umeå, Sweden
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16
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Amato J, D'Aria F, Marzano S, Iaccarino N, Randazzo A, Giancola C, Pagano B. On the thermodynamics of folding of an i-motif DNA in solution under favorable conditions. Phys Chem Chem Phys 2021; 23:15030-15037. [PMID: 34151914 DOI: 10.1039/d1cp01779a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Under slightly acidic conditions, cytosine-rich DNA sequences can form non-canonical secondary structures called i-motifs, which occur as four stretches of cytosine repeats form hemi-protonated C·C+ base pairs. The growing interest in the i-motif structures as important components in functional DNA-based nanotechnology or as potential targets of anticancer drugs, increases the need for a deep understanding of the energetics of their structural transitions. Here, a combination of spectroscopic and calorimetric techniques is used to unravel the thermodynamics of folding of an i-motif DNA under favorable conditions. The results give new insights into the energetic aspects of i-motifs and show that thermodynamic and thermal stability are related but not identical properties of such DNA structures.
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Affiliation(s)
- Jussara Amato
- Department of Pharmacy, University of Naples Federico II, Naples, I-80131, Italy.
| | - Federica D'Aria
- Department of Pharmacy, University of Naples Federico II, Naples, I-80131, Italy.
| | - Simona Marzano
- Department of Pharmacy, University of Naples Federico II, Naples, I-80131, Italy.
| | - Nunzia Iaccarino
- Department of Pharmacy, University of Naples Federico II, Naples, I-80131, Italy.
| | - Antonio Randazzo
- Department of Pharmacy, University of Naples Federico II, Naples, I-80131, Italy.
| | - Concetta Giancola
- Department of Pharmacy, University of Naples Federico II, Naples, I-80131, Italy.
| | - Bruno Pagano
- Department of Pharmacy, University of Naples Federico II, Naples, I-80131, Italy.
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17
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Laouer K, Schmid M, Wien F, Changenet P, Hache F. Folding Dynamics of DNA G-Quadruplexes Probed by Millisecond Temperature Jump Circular Dichroism. J Phys Chem B 2021; 125:8088-8098. [PMID: 34279936 DOI: 10.1021/acs.jpcb.1c01993] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
G-quadruplexes play important roles in cellular regulatory functions, but despite significant experimental and theoretical efforts, their folding mechanisms remain poorly understood. In this context, we developed a T-jump experiment to access the thermal denaturation and renaturation dynamics of short intramolecular G-quadruplexes in vitro, on the time scale of a few hundred milliseconds. With this new setup, we compared the thermal denaturation and renaturation kinetics of three antiparallel topologies made of the human telomeric sequences d[(5'-GGG(TTAGGG)3-3']/Na+ and d[5'-AGGG(TTAGGG)3-3']/Na+ and the thrombin-binding aptamer sequence d[5'-GGTTGGTGTGGTTGG-3']/K+, with those of the parallel topology made of the human CEB25 minisatellite d[5'-AAGGGTGGGTGTAAGTGTGGGTGGGT-3']/Na+. In all cases, exponential kinetics of the order of several hundred milliseconds were observed. Measurements performed for different initial temperatures revealed distinct denaturation and renaturation dynamics, ruling out a simple two-state mechanism. The parallel topology, in which all guanines adopt an anti conformation, displays much slower dynamics than antiparallel topologies associated with very low activation barriers. This behavior can be explained by the constrained conformational space due to the presence of the single-base propeller loops that likely hinders the movement of the coiled DNA strand and reduces the contribution of the entropy during the renaturation process at high temperatures.
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Affiliation(s)
- K Laouer
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, CNRS -INSERM, Institut Polytechnique de Paris, 91128 Cedex Palaiseau, France
| | - M Schmid
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, CNRS -INSERM, Institut Polytechnique de Paris, 91128 Cedex Palaiseau, France
| | - F Wien
- L'orme des merisiers, Synchrotron SOLEIL, 91192 Gif sur Yvette, France
| | - P Changenet
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, CNRS -INSERM, Institut Polytechnique de Paris, 91128 Cedex Palaiseau, France
| | - F Hache
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, CNRS -INSERM, Institut Polytechnique de Paris, 91128 Cedex Palaiseau, France
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18
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Müller D, Bessi I, Richter C, Schwalbe H. The Folding Landscapes of Human Telomeric RNA and DNA G-Quadruplexes are Markedly Different. Angew Chem Int Ed Engl 2021; 60:10895-10901. [PMID: 33539622 PMCID: PMC8252441 DOI: 10.1002/anie.202100280] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 02/04/2021] [Indexed: 01/23/2023]
Abstract
We investigated the folding kinetics of G‐quadruplex (G4) structures by comparing the K+‐induced folding of an RNA G4 derived from the human telomeric repeat‐containing RNA (TERRA25) with a sequence homologous DNA G4 (wtTel25) using CD spectroscopy and real‐time NMR spectroscopy. While DNA G4 folding is biphasic, reveals kinetic partitioning and involves kinetically favoured off‐pathway intermediates, RNA G4 folding is faster and monophasic. The differences in kinetics are correlated to the differences in the folded conformations of RNA vs. DNA G4s, in particular with regard to the conformation around the glycosidic torsion angle χ that uniformly adopts anti conformations for RNA G4s and both, syn and anti conformation for DNA G4s. Modified DNA G4s with 19F bound to C2′ in arabino configuration adopt exclusively anti conformations for χ. These fluoro‐modified DNA (antiTel25) reveal faster folding kinetics and monomorphic conformations similar to RNA G4s, suggesting the correlation between folding kinetics and pathways with differences in χ angle preferences in DNA and RNA, respectively.
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Affiliation(s)
- Diana Müller
- Goethe University Frankfurt/Centre for Biomolecular Magnetic Resonance (BMRZ), Institute for Organic Chemistry and Chemical Biology, Max-von-Laue-Str. 7, 60438, Frankfurt am Main, Germany
| | - Irene Bessi
- Goethe University Frankfurt/Centre for Biomolecular Magnetic Resonance (BMRZ), Institute for Organic Chemistry and Chemical Biology, Max-von-Laue-Str. 7, 60438, Frankfurt am Main, Germany.,Present address: Julius-Maximilians-University Würzburg, Institute of Organic Chemistry, Am Hubland 16, 97074, Würzburg, Germany
| | - Christian Richter
- Goethe University Frankfurt/Centre for Biomolecular Magnetic Resonance (BMRZ), Institute for Organic Chemistry and Chemical Biology, Max-von-Laue-Str. 7, 60438, Frankfurt am Main, Germany
| | - Harald Schwalbe
- Goethe University Frankfurt/Centre for Biomolecular Magnetic Resonance (BMRZ), Institute for Organic Chemistry and Chemical Biology, Max-von-Laue-Str. 7, 60438, Frankfurt am Main, Germany
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19
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Grün JT, Blümler A, Burkhart I, Wirmer-Bartoschek J, Heckel A, Schwalbe H. Unraveling the Kinetics of Spare-Tire DNA G-Quadruplex Folding. J Am Chem Soc 2021; 143:6185-6193. [PMID: 33872503 DOI: 10.1021/jacs.1c01089] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The folding of DNA G-quadruplexes (G4) is essential to regulate expression of oncogenes and involves polymorphic long-lived intermediate states. G4 formation requires four G-tracts, but human gene-promoters often contain multiple G-tracts that act as spare-tires. These additional G-tracts are highly conserved and add multiple layers of functional complexity, as they are crucial to maintain G4 function after oxidative damage. Herein, we unravel the folding dynamics of the G4 sequence containing five G-tracts from cMYC, the major proliferation-driving oncogene. We devise a general method to induce folding at constant experimental conditions using a photochemical trapping strategy. Our data dissect the individual kinetics and thermodynamics of the spare-tire mechanism of cMYC-G4.
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Affiliation(s)
- J Tassilo Grün
- Institute for Organic Chemistry and Chemical Biology, Goethe University Frankfurt am Main, Frankfurt 60323, Germany.,Center of Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt am Main, Frankfurt 60323, Germany
| | - Anja Blümler
- Institute for Organic Chemistry and Chemical Biology, Goethe University Frankfurt am Main, Frankfurt 60323, Germany
| | - Ines Burkhart
- Institute for Organic Chemistry and Chemical Biology, Goethe University Frankfurt am Main, Frankfurt 60323, Germany.,Center of Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt am Main, Frankfurt 60323, Germany
| | - Julia Wirmer-Bartoschek
- Institute for Organic Chemistry and Chemical Biology, Goethe University Frankfurt am Main, Frankfurt 60323, Germany.,Center of Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt am Main, Frankfurt 60323, Germany
| | - Alexander Heckel
- Institute for Organic Chemistry and Chemical Biology, Goethe University Frankfurt am Main, Frankfurt 60323, Germany
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology, Goethe University Frankfurt am Main, Frankfurt 60323, Germany.,Center of Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt am Main, Frankfurt 60323, Germany
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20
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The Folding Landscapes of Human Telomeric RNA and DNA G‐Quadruplexes are Markedly Different. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202100280] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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21
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Živković ML, Gajarský M, Beková K, Stadlbauer P, Vicherek L, Petrová M, Fiala R, Rosenberg I, Šponer J, Plavec J, Trantírek L. Insight into formation propensity of pseudocircular DNA G-hairpins. Nucleic Acids Res 2021; 49:2317-2332. [PMID: 33524154 PMCID: PMC7913771 DOI: 10.1093/nar/gkab029] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 12/21/2020] [Accepted: 01/11/2021] [Indexed: 11/13/2022] Open
Abstract
We recently showed that Saccharomyces cerevisiae telomeric DNA can fold into an unprecedented pseudocircular G-hairpin (PGH) structure. However, the formation of PGHs in the context of extended sequences, which is a prerequisite for their function in vivo and their applications in biotechnology, has not been elucidated. Here, we show that despite its ‘circular’ nature, PGHs tolerate single-stranded (ss) protrusions. High-resolution NMR structure of a novel member of PGH family reveals the atomistic details on a junction between ssDNA and PGH unit. Identification of new sequences capable of folding into one of the two forms of PGH helped in defining minimal sequence requirements for their formation. Our time-resolved NMR data indicate a possibility that PGHs fold via a complex kinetic partitioning mechanism and suggests the existence of K+ ion-dependent PGH folding intermediates. The data not only provide an explanation of cation-type-dependent formation of PGHs, but also explain the unusually large hysteresis between PGH melting and annealing noted in our previous study. Our findings have important implications for DNA biology and nanotechnology. Overrepresentation of sequences able to form PGHs in the evolutionary-conserved regions of the human genome implies their functionally important biological role(s).
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Affiliation(s)
- Martina Lenarčič Živković
- Central European Institute of Technology, Masaryk University, Brno 62500, Czech Republic.,Slovenian NMR Centre, National Institute of Chemistry, Ljubljana SI-1000, Slovenia
| | - Martin Gajarský
- Central European Institute of Technology, Masaryk University, Brno 62500, Czech Republic.,National Centre for Biomolecular Research, Masaryk University, Brno 62500, Czech Republic
| | - Kateřina Beková
- Central European Institute of Technology, Masaryk University, Brno 62500, Czech Republic.,National Centre for Biomolecular Research, Masaryk University, Brno 62500, Czech Republic
| | - Petr Stadlbauer
- Institute of Biophysics of the Czech Academy of Sciences, Brno 61265, Czech Republic
| | - Lukáš Vicherek
- Central European Institute of Technology, Masaryk University, Brno 62500, Czech Republic
| | - Magdalena Petrová
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czech Republic
| | - Radovan Fiala
- Central European Institute of Technology, Masaryk University, Brno 62500, Czech Republic
| | - Ivan Rosenberg
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czech Republic
| | - Jiří Šponer
- Central European Institute of Technology, Masaryk University, Brno 62500, Czech Republic.,Institute of Biophysics of the Czech Academy of Sciences, Brno 61265, Czech Republic
| | - Janez Plavec
- Slovenian NMR Centre, National Institute of Chemistry, Ljubljana SI-1000, Slovenia.,EN-FIST Centre of Excellence, Ljubljana SI-1001, Slovenia.,Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana SI-1000, Slovenia
| | - Lukáš Trantírek
- Central European Institute of Technology, Masaryk University, Brno 62500, Czech Republic
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22
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Harkness RW, Hennecker C, Grün JT, Blümler A, Heckel A, Schwalbe H, Mittermaier AK. Parallel reaction pathways accelerate folding of a guanine quadruplex. Nucleic Acids Res 2021; 49:1247-1262. [PMID: 33469659 PMCID: PMC7897495 DOI: 10.1093/nar/gkaa1286] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 12/21/2020] [Accepted: 12/27/2020] [Indexed: 02/07/2023] Open
Abstract
G-quadruplexes (G4s) are four-stranded, guanine-rich nucleic acid structures that can influence a variety of biological processes such as the transcription and translation of genes and DNA replication. In many cases, a single G4-forming nucleic acid sequence can adopt multiple different folded conformations that interconvert on biologically relevant timescales, entropically stabilizing the folded state. The coexistence of different folded conformations also suggests that there are multiple pathways leading from the unfolded to the folded state ensembles, potentially modulating the folding rate and biological activity. We have developed an experimental method for quantifying the contributions of individual pathways to the folding of conformationally heterogeneous G4s that is based on mutagenesis, thermal hysteresis kinetic experiments and global analysis, and validated our results using photocaged kinetic NMR experiments. We studied the regulatory Pu22 G4 from the c-myc oncogene promoter, which adopts at least four distinct folded isomers. We found that the presence of four parallel pathways leads to a 2.5-fold acceleration in folding; that is, the effective folding rate from the unfolded to folded ensembles is 2.5 times as large as the rate constant for the fastest individual pathway. Since many G4 sequences can adopt many more than four isomers, folding accelerations of more than an order of magnitude are possible via this mechanism.
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Affiliation(s)
- Robert W Harkness
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada.,Department of Chemistry, McGill University, Montreal, QC H3A 0B8, Canada
| | | | - J Tassilo Grün
- Institute for Organic Chemistry and Chemical Biology, Goethe University, Frankfurt am Main 60438, Germany.,Center of Biomolecular Magnetic Resonance (BMRZ), Goethe University, Frankfurt am Main 60438, Germany
| | - Anja Blümler
- Institute for Organic Chemistry and Chemical Biology, Goethe University, Frankfurt am Main 60438, Germany
| | - Alexander Heckel
- Institute for Organic Chemistry and Chemical Biology, Goethe University, Frankfurt am Main 60438, Germany
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology, Goethe University, Frankfurt am Main 60438, Germany.,Center of Biomolecular Magnetic Resonance (BMRZ), Goethe University, Frankfurt am Main 60438, Germany
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23
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A two-quartet G-quadruplex topology of human KIT2 is conformationally selected by a perylene derivative. Biochimie 2020; 179:77-84. [DOI: 10.1016/j.biochi.2020.09.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/11/2020] [Accepted: 09/14/2020] [Indexed: 12/19/2022]
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24
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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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25
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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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26
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Bian Y, Song F, Zhang J, Yu J, Wang J, Wang W. Insights into the Kinetic Partitioning Folding Dynamics of the Human Telomeric G-Quadruplex from Molecular Simulations and Machine Learning. J Chem Theory Comput 2020; 16:5936-5947. [PMID: 32794754 DOI: 10.1021/acs.jctc.0c00340] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The human telomeric DNA G-quadruplex follows a kinetic partitioning folding mechanism. The underlying folding landscape potentially has many minima separated by high free-energy barriers. However, using current theoretical models to characterize this complex folding landscape has remained a challenging problem. In this study, by developing a hybrid atomistic structure-based model that merges structural information on the hybrid-1, hybrid-2, and chair-type G-quadruplex topologies, we investigated a kinetic partitioning folding process of human telomeric DNA involving three native folds. The model was validated as it reproduced the experimental observation that the hybrid-1 conformation is the major fold and the hybrid-2 conformation is kinetically more accessible. A three-step mechanism was revealed for the formation of the hybrid-1 conformation, while a two-step mechanism was demonstrated for the formation of hybrid-2 and chair-type conformations. Likewise, a class of state in which structures adopted inappropriate combinations of syn/anti guanine nucleotides was found to greatly slow down the folding process. In addition, by employing the XGBoost machine learning algorithm, three interatom distances and six dihedral angles were identified as essential internal coordinates to represent the low-dimensional folding landscape. The strategy of coupling the multibasin model and the machine learning algorithm may be useful to investigate the conformational dynamics of other multistate biomolecules.
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Affiliation(s)
- Yunqiang Bian
- Shandong Provincial Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou 253023, China.,National Laboratory of Solid State Microstructure, Department of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Feng Song
- Shandong Provincial Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou 253023, China
| | - Jian Zhang
- National Laboratory of Solid State Microstructure, Department of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Jiafeng Yu
- Shandong Provincial Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou 253023, China
| | - Jihua Wang
- Shandong Provincial Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou 253023, China
| | - Wei Wang
- National Laboratory of Solid State Microstructure, Department of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
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27
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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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28
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Deiana M, Chand K, Jamroskovic J, Das RN, Obi I, Chorell E, Sabouri N. A site-specific self-assembled light-up rotor probe for selective recognition and stabilization of c-MYC G-quadruplex DNA. NANOSCALE 2020; 12:12950-12957. [PMID: 32525170 DOI: 10.1039/d0nr03404e] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Direct and unambiguous evidence of the formation of G-quadruplexes (G4s) in human cells have shown their implication in several key biological events and has emphasized their role as important targets for small-molecule cancer therapeutics. Here, we report on the first example of a self-assembled molecular-rotor G4-binder able to discriminate between an extensive panel of G4 and non-G4 structures and to selectively light-up (up to 64-fold), bind (nanomolar range), and stabilize the c-MYC promoter G4 DNA. In particular, association with the c-MYC G4 triggers the disassembly of its supramolecular state (disaggregation-induced emission, DIE) and induces geometrical restrictions (motion-induced change in emission, MICE) leading to a significant enhancement of its emission yield. Moreover, this optical reporter is able to selectively stabilize the c-MYC G4 and inhibit DNA synthesis. Finally, by using confocal laser-scanning microscopy (CLSM) we show the ability of this compound to localize primarily in the subnuclear G4-rich compartments of cancer cells. This work provides a benchmark for the future design and development of a new generation of smart sequence-selective supramolecular G4-binders that combine outstanding sensing and stability properties, to be utilized in anti-cancer therapy.
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Affiliation(s)
- Marco Deiana
- Department of Medical Biochemistry and Biophysics, Umeå University, 90187 Umeå, Sweden.
| | - Karam Chand
- Department of Chemistry, Umeå University, 90187 Umeå, Sweden.
| | - Jan Jamroskovic
- Department of Medical Biochemistry and Biophysics, Umeå University, 90187 Umeå, Sweden.
| | | | - Ikenna Obi
- Department of Medical Biochemistry and Biophysics, Umeå University, 90187 Umeå, Sweden.
| | - Erik Chorell
- Department of Chemistry, Umeå University, 90187 Umeå, Sweden.
| | - Nasim Sabouri
- Department of Medical Biochemistry and Biophysics, Umeå University, 90187 Umeå, Sweden.
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29
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Nguyen TQN, Lim KW, Phan AT. Folding Kinetics of G-Quadruplexes: Duplex Stem Loops Drive and Accelerate G-Quadruplex Folding. J Phys Chem B 2020; 124:5122-5130. [DOI: 10.1021/acs.jpcb.0c02548] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Thi Quynh Ngoc Nguyen
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Kah Wai Lim
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Anh Tuân Phan
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- NTU Institute of Structural Biology, Nanyang Technological University, Singapore 636921, Singapore
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30
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Liu L, Ma C, Wells JW, Chalikian TV. Conformational Preferences of DNA Strands from the Promoter Region of the c-MYC Oncogene. J Phys Chem B 2020; 124:751-762. [PMID: 31923361 DOI: 10.1021/acs.jpcb.9b10518] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We characterized the conformational preferences of DNA in an equimolar mixture of complementary G-rich and C-rich strands from the promoter region of the c-MYC oncogene. Our CD-based approach presupposes that the CD spectrum of such a mixture is the spectral sum of the constituent duplex, G-quadruplex, i-motif, and coiled conformations. Spectra were acquired over a range of temperatures at different pHs and concentrations of KCl. Each spectrum was unmixed in terms of the predetermined spectra of the constituent conformational states to obtain the corresponding weighting factors for their fractional contributions to the total population of DNA. The temperature dependences of those contributions then were analyzed in concert according to a model based on a thermodynamic representation of the underlying equilibria. Fitted estimates of the melting enthalpy and temperature obtained for the duplex, G-quadruplex, and i-motif imply that the driving force behind dissociation of the duplex and the concomitant formation of tetrahelical structures is the folding of the G-strand into the G-quadruplex. The liberated C-strand adopts the i-motif conformation at acidic pH and exists in the coiled state at neutral pH. The i-motif alone cannot induce dissociation of the duplex even at pH 5.0, at which it is most stable. Under the physiological conditions of neutral pH, elevated potassium, and room temperature, the duplex and G-quadruplex conformations coexist with the C-strand in the coiled state. Taken together, our results suggest a novel, thermodynamically controlled mechanism for the regulation of gene expression.
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Affiliation(s)
- Lutan Liu
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy , University of Toronto , 144 College Street , Toronto , Ontario M5S 3M2 , Canada
| | - Congshan Ma
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy , University of Toronto , 144 College Street , Toronto , Ontario M5S 3M2 , Canada
| | - James W Wells
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy , University of Toronto , 144 College Street , Toronto , Ontario M5S 3M2 , Canada
| | - Tigran V Chalikian
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy , University of Toronto , 144 College Street , Toronto , Ontario M5S 3M2 , Canada
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31
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Molecular dynamics simulations of G-quadruplexes: The basic principles and their application to folding and ligand binding. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 2020. [DOI: 10.1016/bs.armc.2020.04.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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32
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Stadlbauer P, Kührová P, Vicherek L, Banáš P, Otyepka M, Trantírek L, Šponer J. Parallel G-triplexes and G-hairpins as potential transitory ensembles in the folding of parallel-stranded DNA G-Quadruplexes. Nucleic Acids Res 2019; 47:7276-7293. [PMID: 31318975 PMCID: PMC6698752 DOI: 10.1093/nar/gkz610] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 06/26/2019] [Accepted: 07/03/2019] [Indexed: 12/29/2022] Open
Abstract
Guanine quadruplexes (G4s) are non-canonical nucleic acids structures common in important genomic regions. Parallel-stranded G4 folds are the most abundant, but their folding mechanism is not fully understood. Recent research highlighted that G4 DNA molecules fold via kinetic partitioning mechanism dominated by competition amongst diverse long-living G4 folds. The role of other intermediate species such as parallel G-triplexes and G-hairpins in the folding process has been a matter of debate. Here, we use standard and enhanced-sampling molecular dynamics simulations (total length of ∼0.9 ms) to study these potential folding intermediates. We suggest that parallel G-triplex per se is rather an unstable species that is in local equilibrium with a broad ensemble of triplex-like structures. The equilibrium is shifted to well-structured G-triplex by stacked aromatic ligand and to a lesser extent by flanking duplexes or nucleotides. Next, we study propeller loop formation in GGGAGGGAGGG, GGGAGGG and GGGTTAGGG sequences. We identify multiple folding pathways from different unfolded and misfolded structures leading towards an ensemble of intermediates called cross-like structures (cross-hairpins), thus providing atomistic level of description of the single-molecule folding events. In summary, the parallel G-triplex is a possible, but not mandatory short-living (transitory) intermediate in the folding of parallel-stranded G4.
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Affiliation(s)
- Petr Stadlbauer
- Institute of Biophysics of the Czech Academy of Sciences, v. v. i., Královopolská 135, 612 65 Brno, Czech Republic.,Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacky University, Šlechtitelů 27, 771 46 Olomouc, Czech Republic
| | - Petra Kührová
- Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacky University, Šlechtitelů 27, 771 46 Olomouc, Czech Republic.,Department of Physical Chemistry, Faculty of Science, Palacky University, 17. listopadu 12, 771 46 Olomouc, Czech Republic
| | - Lukáš Vicherek
- Central European Institute of Technology, Masaryk University, Kamenice 753/5, 625 00 Brno, Czech Republic
| | - Pavel Banáš
- Institute of Biophysics of the Czech Academy of Sciences, v. v. i., Královopolská 135, 612 65 Brno, Czech Republic.,Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacky University, Šlechtitelů 27, 771 46 Olomouc, Czech Republic.,Department of Physical Chemistry, Faculty of Science, Palacky University, 17. listopadu 12, 771 46 Olomouc, Czech Republic
| | - Michal Otyepka
- Institute of Biophysics of the Czech Academy of Sciences, v. v. i., Královopolská 135, 612 65 Brno, Czech Republic.,Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacky University, Šlechtitelů 27, 771 46 Olomouc, Czech Republic.,Department of Physical Chemistry, Faculty of Science, Palacky University, 17. listopadu 12, 771 46 Olomouc, Czech Republic
| | - Lukáš Trantírek
- Institute of Biophysics of the Czech Academy of Sciences, v. v. i., Královopolská 135, 612 65 Brno, Czech Republic.,Central European Institute of Technology, Masaryk University, Kamenice 753/5, 625 00 Brno, Czech Republic
| | - Jiří Šponer
- Institute of Biophysics of the Czech Academy of Sciences, v. v. i., Královopolská 135, 612 65 Brno, Czech Republic.,Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacky University, Šlechtitelů 27, 771 46 Olomouc, Czech Republic.,Central European Institute of Technology, Masaryk University, Kamenice 753/5, 625 00 Brno, Czech Republic
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