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Rudnizky S, Murray PJ, Wolfe CH, Ha T. Single-Macromolecule Studies of Eukaryotic Genomic Maintenance. Annu Rev Phys Chem 2024; 75:209-230. [PMID: 38382570 DOI: 10.1146/annurev-physchem-090722-010601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Genomes are self-organized and self-maintained as long, complex macromolecules of chromatin. The inherent heterogeneity, stochasticity, phase separation, and chromatin dynamics of genome operation make it challenging to study genomes using ensemble methods. Various single-molecule force-, fluorescent-, and sequencing-based techniques rooted in different disciplines have been developed to fill critical gaps in the capabilities of bulk measurements, each providing unique, otherwise inaccessible, insights into the structure and maintenance of the genome. Capable of capturing molecular-level details about the organization, conformational changes, and packaging of genetic material, as well as processive and stochastic movements of maintenance factors, a single-molecule toolbox provides an excellent opportunity for collaborative research to understand how genetic material functions in health and malfunctions in disease. In this review, we discuss novel insights brought to genomic sciences by single-molecule techniques and their potential to continue to revolutionize the field-one molecule at a time.
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Affiliation(s)
- Sergei Rudnizky
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Peter J Murray
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts, USA;
| | - Clara H Wolfe
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Taekjip Ha
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts, USA;
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
- Howard Hughes Medical Institute, Boston Children's Hospital, Boston, Massachusetts, USA
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2
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Sahoo BR, Kocman V, Clark N, Myers N, Deng X, Wong EL, Yang HJ, Kotar A, Guzman BB, Dominguez D, Plavec J, Bardwell JCA. Protein G-quadruplex interactions and their effects on phase transitions and protein aggregation. Nucleic Acids Res 2024; 52:4702-4722. [PMID: 38572746 PMCID: PMC11077067 DOI: 10.1093/nar/gkae229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 03/14/2024] [Accepted: 03/22/2024] [Indexed: 04/05/2024] Open
Abstract
The SERF family of proteins were originally discovered for their ability to accelerate amyloid formation. Znf706 is an uncharacterized protein whose N-terminus is homologous to SERF proteins. We show here that human Znf706 can promote protein aggregation and amyloid formation. Unexpectedly, Znf706 specifically interacts with stable, non-canonical nucleic acid structures known as G-quadruplexes. G-quadruplexes can affect gene regulation and suppress protein aggregation; however, it is unknown if and how these two activities are linked. We find Znf706 binds preferentially to parallel G-quadruplexes with low micromolar affinity, primarily using its N-terminus, and upon interaction, its dynamics are constrained. G-quadruplex binding suppresses Znf706's ability to promote protein aggregation. Znf706 in conjunction with G-quadruplexes therefore may play a role in regulating protein folding. RNAseq analysis shows that Znf706 depletion specifically impacts the mRNA abundance of genes that are predicted to contain high G-quadruplex density. Our studies give insight into how proteins and G-quadruplexes interact, and how these interactions affect both partners and lead to the modulation of protein aggregation and cellular mRNA levels. These observations suggest that the SERF family of proteins, in conjunction with G-quadruplexes, may have a broader role in regulating protein folding and gene expression than previously appreciated.
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Affiliation(s)
- Bikash R Sahoo
- Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Vojč Kocman
- National Institute of Chemistry, Ljubljana, Slovenia
| | - Nathan Clark
- Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Nikhil Myers
- Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Xiexiong Deng
- Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Ee L Wong
- Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Harry J Yang
- Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Anita Kotar
- National Institute of Chemistry, Ljubljana, Slovenia
| | | | | | - Janez Plavec
- National Institute of Chemistry, Ljubljana, Slovenia
| | - James C A Bardwell
- Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
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3
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Pokorná P, Mlýnský V, Bussi G, Šponer J, Stadlbauer P. Molecular dynamics simulations reveal the parallel stranded d(GGGA) 3GGG DNA quadruplex folds via multiple paths from a coil-like ensemble. Int J Biol Macromol 2024; 261:129712. [PMID: 38286387 DOI: 10.1016/j.ijbiomac.2024.129712] [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: 09/21/2023] [Revised: 01/10/2024] [Accepted: 01/16/2024] [Indexed: 01/31/2024]
Abstract
G-quadruplexes (G4s) are non-canonical nucleic acid structures that fold through complex processes. Characterization of the G4 folding landscape may help to elucidate biological roles of G4s but is challenging both experimentally and computationally. Here, we achieved complete folding of a three-quartet parallel DNA G4 with (GGGA)3GGG sequence using all-atom explicit-solvent enhanced-sampling molecular dynamics (MD) simulations. The simulations suggested early formation of guanine stacks in the G-tracts, which behave as semi-rigid blocks in the folding process. The folding continues via the formation of a collapsed compact coil-like ensemble. Structuring of the G4 from the coil then proceeds via various cross-like, hairpin, slip-stranded and two-quartet ensembles and can bypass the G-triplex structure. Folding of the parallel G4 does not appear to involve any salient intermediates and is a multi-pathway process. We also carried out an extended set of simulations of parallel G-hairpins. While parallel G-hairpins are extremely unstable when isolated, they are more stable inside the coil structure. On the methodology side, we show that the AMBER DNA force field predicts the folded G4 to be less stable than the unfolded ensemble, uncovering substantial force-field issues. Overall, we provide unique atomistic insights into the folding landscape of parallel-stranded G4 but also reveal limitations of current state-of-the-art MD techniques.
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Affiliation(s)
- Pavlína Pokorná
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, Brno 61200, Czech Republic
| | - Vojtěch Mlýnský
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, Brno 61200, Czech Republic
| | - Giovanni Bussi
- Scuola Internazionale Superiore di Studi Avanzati (SISSA), via Bonomea 265, Trieste 34136, Italy
| | - Jiří Šponer
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, Brno 61200, Czech Republic
| | - Petr Stadlbauer
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, Brno 61200, Czech Republic.
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4
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Gopalakrishnan V, Roy U, Srivastava S, Kariya KM, Sharma S, Javedakar SM, Choudhary B, Raghavan SC. Delineating the mechanism of fragility at BCL6 breakpoint region associated with translocations in diffuse large B cell lymphoma. Cell Mol Life Sci 2024; 81:21. [PMID: 38196006 PMCID: PMC11072719 DOI: 10.1007/s00018-023-05042-w] [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: 06/07/2023] [Revised: 11/05/2023] [Accepted: 11/07/2023] [Indexed: 01/11/2024]
Abstract
BCL6 translocation is one of the most common chromosomal translocations in cancer and results in its enhanced expression in germinal center B cells. It involves the fusion of BCL6 with any of its twenty-six Ig and non-Ig translocation partners associated with diffuse large B cell lymphoma (DLBCL). Despite being discovered long back, the mechanism of BCL6 fragility is largely unknown. Analysis of the translocation breakpoints in 5' UTR of BCL6 reveals the clustering of most of the breakpoints around a region termed Cluster II. In silico analysis of the breakpoint cluster sequence identified sequence motifs that could potentially fold into non-B DNA. Results revealed that the Cluster II sequence folded into overlapping hairpin structures and identified sequences that undergo base pairing at the stem region. Further, the formation of cruciform DNA blocked DNA replication. The sodium bisulfite modification assay revealed the single-strandedness of the region corresponding to hairpin DNA in both strands of the genome. Further, we report the formation of intramolecular parallel G4 and triplex DNA, at Cluster II. Taken together, our studies reveal that multiple non-canonical DNA structures exist at the BCL6 cluster II breakpoint region and contribute to the fragility leading to BCL6 translocation in DLBCL patients.
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Affiliation(s)
- Vidya Gopalakrishnan
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560 012, India
- Institute of Bioinformatics and Applied Biotechnology, Electronics City, Bangalore, 560 100, India
- Department of Zoology, St. Joseph's College (Autonomous), Irinjalakuda, Kerala, 680121, India
| | - Urbi Roy
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560 012, India
| | - Shikha Srivastava
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560 012, India
- Department of Bioscience and Biotechnology, Banasthali Vidyapith, Tonk, Rajasthan, 304022, India
| | - Khyati M Kariya
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560 012, India
| | - Shivangi Sharma
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560 012, India
| | - Saniya M Javedakar
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560 012, India
| | - Bibha Choudhary
- Institute of Bioinformatics and Applied Biotechnology, Electronics City, Bangalore, 560 100, India.
| | - Sathees C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560 012, India.
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5
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Shiekh S, Kodikara SG, Balci H. Structure, Topology, and Stability of Multiple G-quadruplexes in Long Telomeric Overhangs. J Mol Biol 2024; 436:168205. [PMID: 37481156 PMCID: PMC10799177 DOI: 10.1016/j.jmb.2023.168205] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 07/05/2023] [Accepted: 07/12/2023] [Indexed: 07/24/2023]
Abstract
Telomeres and their single stranded overhangs gradually shorten with successive cell divisions, as part of the natural aging process, but can be elongated by telomerase, a nucleoprotein complex which is activated in the majority of cancers. This prominent implication in cancer and aging has made the repetitive telomeric sequences (TTAGGG repeats) and the G-quadruplex structures that form in their overhangs the focus of intense research in the past several decades. However, until recently most in vitro efforts to understand the structure, stability, dynamics, and interactions of telomeric overhangs had been focused on short sequences that are not representative of longer sequences encountered in a physiological setting. In this review, we will provide a broad perspective about telomeres and associated factors, and introduce the agents and structural characteristics involved in organizing, maintaining, and protecting telomeric DNA. We will also present a summary of recent research performed on long telomeric sequences, nominally defined as those that can form two or more tandem G-quadruplexes, i.e., which contain eight or more TTAGGG repeats. Results of experimental studies using a broad array of experimental tools, in addition to recent computational efforts will be discussed, particularly in terms of their implications for the stability, folding topology, and compactness of the tandem G-quadruplexes that form in long telomeric overhangs.
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Affiliation(s)
- Sajad Shiekh
- Department of Physics, Kent State University, Kent, OH 44242, USA
| | | | - Hamza Balci
- Department of Physics, Kent State University, Kent, OH 44242, USA.
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6
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Aznauryan M, Birkedal V. Dynamics of G-Quadruplex Formation under Molecular Crowding. J Phys Chem Lett 2023; 14:10354-10360. [PMID: 37948600 DOI: 10.1021/acs.jpclett.3c02453] [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: 11/12/2023]
Abstract
G-quadruplex (G4) structures assemble from guanine-rich DNA sequences and are believed to regulate several key cellular processes. G4 formation and conformational interconversions are well-established to occur dynamically in vitro. However, a clear understanding of G4 formation dynamics in cells as well as under conditions mimicking the cellular environment is missing. To fill this gap, we have investigated the G4 dynamics in molecularly crowded solutions, thus replicating the effect of the excluded volume present in cells. The results show that the volume exclusion exerted by large crowding agents accelerates the rate of G4 formation by at least an order of magnitude, leading to significant G4 stabilization. Extrapolation from our experimental data predicts crowding-induced G4 stabilization by more than 3 kcal/mol, under crowding levels found in the cellular environment. Such effects are likely to be important for G4-driven regulatory functions.
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Affiliation(s)
- Mikayel Aznauryan
- Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark
- Univ. Bordeaux, ARNA Laboratory, INSERM U1212, CNRS UMR 5320, Institut Européen de Chimie et Biologie, 33607 Pessac, France
| | - Victoria Birkedal
- Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark
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7
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Nicholson DA, Nesbitt DJ. Kinetic and Thermodynamic Control of G-Quadruplex Polymorphism by Na + and K + Cations. J Phys Chem B 2023; 127:6842-6855. [PMID: 37504511 DOI: 10.1021/acs.jpcb.3c01001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
G-Quadruplexes (G4s) are ubiquitous nucleic acid folding motifs that exhibit structural diversity that is dependent on cationic conditions. In this work, we exploit temperature-controlled single-molecule fluorescence resonance energy transfer (smFRET) to elucidate the kinetic and thermodynamic mechanisms by which monovalent cations (K+ and Na+) impact folding topologies for a simple G-quadruplex sequence (5'-GGG-(TAAGGG)3-3') with a three-state folding equilibrium. Kinetic measurements indicate that Na+ and K+ influence G4 formation in two distinctly different ways: the presence of Na+ modestly enhances an antiparallel G4 topology through an induced fit (IF) mechanism with a low affinity (Kd = 228 ± 26 mM), while K+ drives G4 into a parallel/hybrid topology via a conformational selection (CS) mechanism with much higher affinity (Kd = 1.9 ± 0.2 mM). Additionally, temperature-dependent studies of folding rate constants and equilibrium ratios reveal distinctly different thermodynamic driving forces behind G4 binding to K+ (ΔH°bind > 0, ΔS°bind > 0) versus Na+ (ΔH°bind < 0, ΔS°bind < 0), which further illuminates the diversity of the possible pathways for monovalent facilitation of G-quadruplex folding.
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Affiliation(s)
- David A Nicholson
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, United States
- Department of Chemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - David J Nesbitt
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, United States
- Department of Chemistry, University of Colorado, Boulder, Colorado 80309, United States
- Department of Physics, University of Colorado, Boulder, Colorado 80309, United States
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8
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Han ZQ, Wen LN. Application of G-quadruplex targets in gastrointestinal cancers: Advancements, challenges and prospects. World J Gastrointest Oncol 2023; 15:1149-1173. [PMID: 37546556 PMCID: PMC10401460 DOI: 10.4251/wjgo.v15.i7.1149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Revised: 04/11/2023] [Accepted: 05/08/2023] [Indexed: 07/12/2023] Open
Abstract
Genomic instability and inflammation are considered to be two enabling characteristics that support cancer development and progression. G-quadruplex structure is a key element that contributes to genomic instability and inflammation. G-quadruplexes were once regarded as simply an obstacle that can block the transcription of oncogenes. A ligand targeting G-quadruplexes was found to have anticancer activity, making G-quadruplexes potential anticancer targets. However, further investigation has revealed that G-quadruplexes are widely distributed throughout the human genome and have many functions, such as regulating DNA replication, DNA repair, transcription, translation, epigenetics, and inflammatory response. G-quadruplexes play double regulatory roles in transcription and translation. In this review, we focus on G-quadruplexes as novel targets for the treatment of gastrointestinal cancers. We summarize the application basis of G-quadruplexes in gastrointestinal cancers, including their distribution sites, structural characteristics, and physiological functions. We describe the current status of applications for the treatment of esophageal cancer, pancreatic cancer, hepatocellular carcinoma, gastric cancer, colorectal cancer, and gastrointestinal stromal tumors, as well as the associated challenges. Finally, we review the prospective clinical applications of G-quadruplex targets, providing references for targeted treatment strategies in gastrointestinal cancers.
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Affiliation(s)
- Zong-Qiang Han
- Department of Laboratory Medicine, Beijing Xiaotangshan Hospital, Beijing 102211, China
| | - Li-Na Wen
- Department of Clinical Nutrition, Beijing Shijitan Hospital, Capital Medical University, Beijing 100038, China
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Khatik SY, Sudhakar S, Mishra S, Kalia J, Pradeepkumar PI, Srivatsan SG. Probing juxtaposed G-quadruplex and hairpin motifs using a responsive nucleoside probe: a unique scaffold for chemotherapy. Chem Sci 2023; 14:5627-5637. [PMID: 37265741 PMCID: PMC10231310 DOI: 10.1039/d3sc00519d] [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: 01/30/2023] [Accepted: 04/30/2023] [Indexed: 06/03/2023] Open
Abstract
Paucity of efficient probes and small molecule ligands that can distinguish different G-quadruplex (GQ) topologies poses challenges not only in understanding their basic structure but also in targeting an individual GQ form from others. Alternatively, G-rich sequences that harbour unique chimeric structural motifs (e.g., GQ-duplex or GQ-hairpin junctions) are perceived as new therapeutic hotspots. In this context, the epidermal growth factor receptor (EGFR) gene, implicated in many cancers, contains a 30 nucleotide G-rich segment in the promoter region, which adopts in vitro two unique architectures each composed of a GQ topology (parallel and hybrid-type) juxtaposed with a hairpin domain. Here, we report the use of a novel dual-app probe, C5-trifluoromethyl benzofuran-modified 2'-deoxyuridine (TFBF-dU), in the systematic analysis of EGFR GQs and their interaction with small molecules by fluorescence and 19F NMR techniques. Notably, distinct fluorescence and 19F NMR signals exhibited by the probe enabled the quantification of the relative population of random, parallel and hybrid-type GQ structures under different conditions, which could not be obtained by conventional CD and 1H NMR techniques. Using the fluorescence component, we quantified ligand binding properties of GQs, whereas the 19F label enabled the assessment of ligand-induced changes in GQ dynamics. Studies also revealed that mutations in the hairpin domain affected GQ formation and stability, which was further functionally verified in polymerase stop assay. We anticipate that these findings and useful properties of the nucleoside probe could be utilized in designing and evaluating binders that jointly target both GQ and hairpin domains for enhanced selectivity and druggability.
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Affiliation(s)
- Saddam Y Khatik
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Pune, Dr Homi Bhabha Road Pune 411008 India
| | - Sruthi Sudhakar
- Department of Chemistry, Indian Institute of Technology Bombay Mumbai 400076 India
| | - Satyajit Mishra
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Bhopal Bhopal Bypass Road, Bhauri Bhopal 462066 India
| | - Jeet Kalia
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Bhopal Bhopal Bypass Road, Bhauri Bhopal 462066 India
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Bhopal Bhopal Bypass Road, Bhauri Bhopal 462066 India
| | - P I Pradeepkumar
- Department of Chemistry, Indian Institute of Technology Bombay Mumbai 400076 India
| | - Seergazhi G Srivatsan
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Pune, Dr Homi Bhabha Road Pune 411008 India
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10
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Kristoffersen E, Coletta A, Lund L, Schiøtt B, Birkedal V. Inhibited complete folding of consecutive human telomeric G-quadruplexes. Nucleic Acids Res 2023; 51:1571-1582. [PMID: 36715345 PMCID: PMC9976873 DOI: 10.1093/nar/gkad004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 12/24/2022] [Accepted: 01/04/2023] [Indexed: 01/31/2023] Open
Abstract
Noncanonical DNA structures, termed G-quadruplexes, are present in human genomic DNA and are important elements in many DNA metabolic processes. Multiple sites in the human genome have G-rich DNA stretches able to support formation of several consecutive G-quadruplexes. One of those sites is the telomeric overhang region that has multiple repeats of TTAGGG and is tightly associated with both cancer and aging. We investigated the folding of consecutive G-quadruplexes in both potassium- and sodium-containing solutions using single-molecule FRET spectroscopy, circular dichroism, thermal melting and molecular dynamics simulations. Our observations show coexistence of partially and fully folded DNA, the latter consisting of consecutive G-quadruplexes. Following the folding process over hours in sodium-containing buffers revealed fast G-quadruplex folding but slow establishment of thermodynamic equilibrium. We find that full consecutive G-quadruplex formation is inhibited by the many DNA structures randomly nucleating on the DNA, some of which are off-path conformations that need to unfold to allow full folding. Our study allows describing consecutive G-quadruplex formation in both nonequilibrium and equilibrium conditions by a unified picture, where, due to the many possible DNA conformations, full folding with consecutive G-quadruplexes as beads on a string is not necessarily achieved.
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Affiliation(s)
- Emil Laust Kristoffersen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus, Denmark
| | - Andrea Coletta
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus, Denmark
| | - Line Mørkholt Lund
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus, Denmark
| | - Birgit Schiøtt
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus, Denmark,Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus, Denmark
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11
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Olejko L, Dutta A, Shahsavar K, Bald I. Influence of Different Salts on the G-Quadruplex Structure Formed from the Reversed Human Telomeric DNA Sequence. Int J Mol Sci 2022; 23:ijms232012206. [PMID: 36293060 PMCID: PMC9602856 DOI: 10.3390/ijms232012206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Revised: 10/07/2022] [Accepted: 10/09/2022] [Indexed: 11/16/2022] Open
Abstract
G-rich telomeric DNA plays a major role in the stabilization of chromosomes and can fold into a plethora of different G-quadruplex structures in the presence of mono- and divalent cations. The reversed human telomeric DNA sequence (5′-(GGG ATT)4; RevHumTel) was previously shown to have interesting properties that can be exploited for chemical sensing and as a chemical switch in DNA nanotechnology. Here, we analyze the specific G-quadruplex structures formed by RevHumTel in the presence of K+, Na+, Mg2+ and Ca2+ cations using circular dichroism spectroscopy (CDS) and Förster resonance energy transfer (FRET) based on fluorescence lifetimes. CDS is able to reveal strand and loop orientations, whereas FRET gives information about the distances between the 5′-end and the 3′-end, and also, the number of G-quadruplex species formed. Based on this combined information we derived specific G-quadruplex structures formed from RevHumTel, i.e., a chair-type and a hybrid-type G-quadruplex structure formed in presence of K+, whereas Na+ induces the formation of up to three different G-quadruplexes (a basket-type, a propeller-type and a hybrid-type structure). In the presence of Mg2+ and Ca2+ two different parallel G-quadruplexes are formed (one of which is a propeller-type structure). This study will support the fundamental understanding of the G-quadruplex formation in different environments and a rational design of G-quadruplex-based applications in sensing and nanotechnology.
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12
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Paul T, Opresko PL, Ha T, Myong S. Vectorial folding of telomere overhang promotes higher accessibility. Nucleic Acids Res 2022; 50:6271-6283. [PMID: 35687089 PMCID: PMC9226509 DOI: 10.1093/nar/gkac401] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 04/20/2022] [Accepted: 06/08/2022] [Indexed: 11/13/2022] Open
Abstract
Human telomere overhang composed of tandem repeats of TTAGGG folds into G-quadruplex (G4). Unlike in an experimental setting in the test tube in which the entire length is allowed to fold at once, inside the cell, the overhang is expected to fold as it is synthesized directionally (5' to 3') and released segmentally by a specialized enzyme, the telomerase. To mimic such vectorial G4 folding process, we employed a superhelicase, Rep-X which can unwind DNA to release the TTAGGG repeats in 5' to 3' direction. We demonstrate that the folded conformation achieved by the refolding of full sequence is significantly different from that of the vectorial folding for two to eight TTAGGG repeats. Strikingly, the vectorially folded state leads to a remarkably higher accessibility to complementary C-rich strand and the telomere binding protein POT1, reflecting a less stably folded state resulting from the vectorial folding. Importantly, our study points to an inherent difference between the co-polymerizing and post-polymerized folding of telomere overhang that can impact telomere architecture and downstream processes.
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Affiliation(s)
- Tapas Paul
- Department of Biophysics, Johns Hopkins University, Baltimore, MD21218, USA
| | - Patricia L Opresko
- Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health, and UPMC Hillman Cancer Center, Pittsburgh, PA15213, USA
| | - Taekjip Ha
- Department of Biophysics, Johns Hopkins University, Baltimore, MD21218, USA.,Physics Frontier Center (Center for Physics of Living Cells), University of Illinois, 1110 W. Green St., Urbana, IL 61801, USA.,Howard Hughes Medical Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Sua Myong
- Department of Biophysics, Johns Hopkins University, Baltimore, MD21218, USA.,Physics Frontier Center (Center for Physics of Living Cells), University of Illinois, 1110 W. Green St., Urbana, IL 61801, USA
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13
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Xi H, Jiang H, Juhas M, Zhang Y. Fluorescence detection of the human angiotensinogen protein by the G-quadruplex aptamer. Analyst 2022; 147:4040-4048. [DOI: 10.1039/d2an01057g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Schematic diagram of AGT detection by a G-quadruplex based fluorescent biosensor.
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Affiliation(s)
- Hui Xi
- College of Science, Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong, 518055, China
| | - Hanlin Jiang
- College of Science, Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong, 518055, China
| | - Mario Juhas
- Medical and Molecular Microbiology Unit, Department of Medicine, Faculty of Science and Medicine, University of Fribourg, Fribourg, 1700, Switzerland
| | - Yang Zhang
- College of Science, Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong, 518055, China
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14
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Masson T, Landras Guetta C, Laigre E, Cucchiarini A, Duchambon P, Teulade-Fichou MP, Verga D. BrdU immuno-tagged G-quadruplex ligands: a new ligand-guided immunofluorescence approach for tracking G-quadruplexes in cells. Nucleic Acids Res 2021; 49:12644-12660. [PMID: 34875077 PMCID: PMC8682774 DOI: 10.1093/nar/gkab1166] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 10/14/2021] [Accepted: 11/10/2021] [Indexed: 11/13/2022] Open
Abstract
G-quadruplexes (G4s) are secondary structures forming in G-rich nucleic acids. G4s are assumed to play critical roles in biology, nonetheless their detection in cells is still challenging. For tracking G4s, synthetic molecules (G4 ligands) can be used as reporters and have found wide application for this purpose through chemical functionalization with a fluorescent tag. However, this approach is limited by a low-labeling degree impeding precise visualization in specific subcellular regions. Herein, we present a new visualization strategy based on the immuno-recognition of 5-bromo-2′-deoxyuridine (5-BrdU) modified G4 ligands, functionalized prior- or post-G4-target binding by CuAAC. Remarkably, recognition of the tag by antibodies leads to the detection of the modified ligands exclusively when bound to a G4 target both in vitro, as shown by ELISA, and in cells, thereby providing a highly efficient G4-ligand Guided Immunofluorescence Staining (G4-GIS) approach. The obtained signal amplification revealed well-defined fluorescent foci located in the perinuclear space and RNase treatment revealed the preferential binding to G4-RNA. Furthermore, ligand treatment affected significantly BG4 foci formation in cells. Our work headed to the development of a new imaging approach combining the advantages of immunostaining and G4-recognition by G4 ligands leading to visualization of G4/ligands species in cells with unrivaled precision and sensitivity.
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Affiliation(s)
- Thibaut Masson
- CNRS UMR9187, INSERM U1196, Institut Curie, PSL Research University, F-91405 Orsay, France.,CNRS UMR9187, INSERM U1196, Université Paris-Saclay, F-91405 Orsay, France
| | - Corinne Landras Guetta
- CNRS UMR9187, INSERM U1196, Institut Curie, PSL Research University, F-91405 Orsay, France.,CNRS UMR9187, INSERM U1196, Université Paris-Saclay, F-91405 Orsay, France
| | - Eugénie Laigre
- CNRS UMR9187, INSERM U1196, Institut Curie, PSL Research University, F-91405 Orsay, France.,CNRS UMR9187, INSERM U1196, Université Paris-Saclay, F-91405 Orsay, France
| | - Anne Cucchiarini
- CNRS UMR9187, INSERM U1196, Institut Curie, PSL Research University, F-91405 Orsay, France.,CNRS UMR9187, INSERM U1196, Université Paris-Saclay, F-91405 Orsay, France
| | - Patricia Duchambon
- CNRS UMR9187, INSERM U1196, Institut Curie, PSL Research University, F-91405 Orsay, France.,CNRS UMR9187, INSERM U1196, Université Paris-Saclay, F-91405 Orsay, France
| | - Marie-Paule Teulade-Fichou
- CNRS UMR9187, INSERM U1196, Institut Curie, PSL Research University, F-91405 Orsay, France.,CNRS UMR9187, INSERM U1196, Université Paris-Saclay, F-91405 Orsay, France
| | - Daniela Verga
- CNRS UMR9187, INSERM U1196, Institut Curie, PSL Research University, F-91405 Orsay, France.,CNRS UMR9187, INSERM U1196, Université Paris-Saclay, F-91405 Orsay, France
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15
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Patra S, Claude JB, Naubron JV, Wenger J. Fast interaction dynamics of G-quadruplex and RGG-rich peptides unveiled in zero-mode waveguides. Nucleic Acids Res 2021; 49:12348-12357. [PMID: 34791437 PMCID: PMC8643622 DOI: 10.1093/nar/gkab1002] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 09/30/2021] [Accepted: 10/11/2021] [Indexed: 11/14/2022] Open
Abstract
G-quadruplexes (GQs), a non-canonical form of DNA, are receiving a huge interest as target sites for potential applications in antiviral and anticancer drug treatments. The biological functions of GQs can be controlled by specifically binding proteins known as GQs binding proteins. Some of the GQs binding proteins contain an arginine and glycine-rich sequence known as RGG peptide. Despite the important role of RGG, the GQs-RGG interaction remains poorly understood. By single molecule measurements, the interaction dynamics can be determined in principle. However, the RGG-GQs interaction occurs at micromolar concentrations, making conventional single-molecule experiments impossible with a diffraction-limited confocal microscope. Here, we use a 120 nm zero-mode waveguide (ZMW) nanoaperture to overcome the diffraction limit. The combination of dual-color fluorescence cross-correlation spectroscopy (FCCS) with FRET is used to unveil the interaction dynamics and measure the association and dissociation rates. Our data show that the RGG-GQs interaction is predominantly driven by electrostatics but that a specific affinity between the RGG sequence and the GQs structure is preserved. The single molecule approach at micromolar concentration is the key to improve our understanding of GQs function and develop its therapeutic applications by screening a large library of GQs-targeting peptides and proteins.
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Affiliation(s)
- Satyajit Patra
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, 13013 Marseille, France
| | - Jean-Benoît Claude
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, 13013 Marseille, France
| | - Jean-Valère Naubron
- Aix Marseille Univ, CNRS, Centrale Marseille, FSCM – Spectropole, 13013 Marseille, France
| | - Jérome Wenger
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, 13013 Marseille, France
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16
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Liu YC, Yang DY, Sheu SY. Insights into the free energy landscape and salt-controlled mechanism of the conformational conversions between human telomeric G-quadruplex structures. Int J Biol Macromol 2021; 191:230-242. [PMID: 34536474 DOI: 10.1016/j.ijbiomac.2021.09.057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 08/23/2021] [Accepted: 09/10/2021] [Indexed: 12/16/2022]
Abstract
G-quadruplexes have become attractive drug targets in cancer therapy. However, due to the polymorphism of G-quadruplex structures, it is difficult to experimentally verify the relevant structures of multiple intermediates and transition states in dynamic equilibrium. Hence, understanding the mechanism by which structural conversions of G-quadruplexes occur is still challenging. We conducted targeted molecular dynamics simulation with umbrella sampling to investigate how salt affects the conformational conversion of human telomeric G-quadruplex. Our results explore a unique view into the structures and energy barrier of the intermediates and transition states in the interconversion process. The pathway of G-quadruplex conformational interconversion was mapped out by a free energy landscape, consisting of branched parallel pathways with multiple energy basins. We propose a salt-controlled mechanism that as the salt concentration increases, the conformational conversion mechanism switches from multi-pathway folding to sequential folding pathways. The hybrid-I and hybrid-II structures are intermediates in the basket-propeller transformation. In high-salt solutions, the conformational conversion upon K+ binding is more feasible than upon Na+ binding. The free energy barrier for conformational conversions ranges from 1.6 to 4.6 kcal/mol. Our work will be beneficial in developing anticancer agents.
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Affiliation(s)
- Yu-Cheng Liu
- Institute of Biomedical Informatics, National Yang Ming Chiao Tung University, Taipei 112, Taiwan
| | - Dah-Yen Yang
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan.
| | - Sheh-Yi Sheu
- Institute of Biomedical Informatics, National Yang Ming Chiao Tung University, Taipei 112, Taiwan; Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei 112, Taiwan.
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17
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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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18
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Vesco G, Lamperti M, Salerno D, Marrano CA, Cassina V, Rigo R, Buglione E, Bondani M, Nicoletto G, Mantegazza F, Sissi C, Nardo L. Double-stranded flanking ends affect the folding kinetics and conformational equilibrium of G-quadruplexes forming sequences within the promoter of KIT oncogene. Nucleic Acids Res 2021; 49:9724-9737. [PMID: 34478543 PMCID: PMC8464035 DOI: 10.1093/nar/gkab674] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 07/13/2021] [Accepted: 09/01/2021] [Indexed: 12/01/2022] Open
Abstract
G-quadruplexes embedded within promoters play a crucial role in regulating the gene expression. KIT is a widely studied oncogene, whose promoter contains three G-quadruplex forming sequences, c-kit1, c-kit2 and c-kit*. For these sequences available studies cover ensemble and single-molecule analyses, although for kit* the latter were limited to a study on a promoter domain comprising all of them. Recently, c-kit2 has been reported to fold according to a multi-step process involving folding intermediates. Here, by exploiting fluorescence resonance energy transfer, both in ensemble and at the single molecule level, we investigated the folding of expressly designed constructs in which, alike in the physiological context, either c-kit2 or c-kit* are flanked by double stranded DNA segments. To assess whether the presence of flanking ends at the borders of the G-quadruplex affects the folding, we studied under the same protocols oligonucleotides corresponding to the minimal G-quadruplex forming sequences. Data suggest that addition of flanking ends results in biasing both the final equilibrium state and the folding kinetics. A previously unconsidered aspect is thereby unravelled, which ought to be taken into account to achieve a deeper insight of the complex relationships underlying the fine tuning of the gene-regulatory properties of these fascinating DNA structures.
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Affiliation(s)
- Guglielmo Vesco
- Department of Science and High Technology, University of Insubria, 22100 Como, Italy
| | - Marco Lamperti
- Department of Physics, Polytechnic of Milan, 23900 Lecco, Italy
| | - Domenico Salerno
- School of Medicine and Surgery, BioNanoMedicine Center NANOMIB, University of Milano-Bicocca, 20854 Vedano al Lambro (MB), Italy
| | - Claudia Adriana Marrano
- School of Medicine and Surgery, BioNanoMedicine Center NANOMIB, University of Milano-Bicocca, 20854 Vedano al Lambro (MB), Italy
| | - Valeria Cassina
- School of Medicine and Surgery, BioNanoMedicine Center NANOMIB, University of Milano-Bicocca, 20854 Vedano al Lambro (MB), Italy
| | - Riccardo Rigo
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, 35131 Padova, Italy
| | - Enrico Buglione
- School of Medicine and Surgery, BioNanoMedicine Center NANOMIB, University of Milano-Bicocca, 20854 Vedano al Lambro (MB), Italy
| | - Maria Bondani
- Institute for Photonics and Nanotechnology, IFN-CNR, 22100 Como, Italy
| | - Giulia Nicoletto
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, 35131 Padova, Italy
| | - Francesco Mantegazza
- School of Medicine and Surgery, BioNanoMedicine Center NANOMIB, University of Milano-Bicocca, 20854 Vedano al Lambro (MB), Italy
| | - Claudia Sissi
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, 35131 Padova, Italy
- CRIBI Biotechnology Center, University of Padova, 35131 Padova, Italy
| | - Luca Nardo
- School of Medicine and Surgery, BioNanoMedicine Center NANOMIB, University of Milano-Bicocca, 20854 Vedano al Lambro (MB), Italy
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19
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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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20
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Aznauryan M, Noer SL, Pedersen CW, Mergny JL, Teulade-Fichou MP, Birkedal V. Ligand Binding to Dynamically Populated G-Quadruplex DNA. Chembiochem 2021; 22:1811-1817. [PMID: 33450114 DOI: 10.1002/cbic.202000792] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 01/11/2021] [Indexed: 12/14/2022]
Abstract
Several small-molecule ligands specifically bind and stabilize G-quadruplex (G4) nucleic acid structures, which are considered to be promising therapeutic targets. G4s are polymorphic structures of varying stability, and their formation is dynamic. Here, we investigate the mechanisms of ligand binding to dynamically populated human telomere G4 DNA by using the bisquinolinium based ligand Phen-DC3 and a combination of single-molecule FRET microscopy, ensemble FRET and CD spectroscopies. Different cations are used to tune G4 polymorphism and folding dynamics. We find that ligand binding occurs to pre-folded G4 structures and that Phen-DC3 also induces G4 formation in unfolded single strands. Following ligand binding to dynamically populated G4s, the DNA undergoes pronounced conformational redistributions that do not involve direct ligand-induced G4 conformational interconversion. On the contrary, the redistribution is driven by ligand-induced G4 folding and trapping of dynamically populated short-lived conformation states. Thus, ligand-induced stabilization does not necessarily require the initial presence of stably folded G4s.
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Affiliation(s)
- Mikayel Aznauryan
- Department of Chemistry and iNANO center, Aarhus University, Gustav Wieds Vej 14, 8000, Aarhus, Denmark.,Present address: Univ. Bordeaux, INSERM, CNRS ARNA, U1212, UMR 5320, IECB, 33600, Pessac, France
| | - Sofie Louise Noer
- Department of Chemistry and iNANO center, Aarhus University, Gustav Wieds Vej 14, 8000, Aarhus, Denmark
| | - Camilla W Pedersen
- Department of Chemistry and iNANO center, Aarhus University, Gustav Wieds Vej 14, 8000, Aarhus, Denmark
| | - Jean-Louis Mergny
- Laboratoire d'Optique et Biosciences (LOB), CNRS UMR7645, INSERM U1182, Ecole Polytechnique, 91128, Palaiseau Cedex, France.,Institute of Biophysics of the CAS, 61265, Brno, Czech Republic
| | - Marie-Paule Teulade-Fichou
- CMBC Laboratory (Chemistry and Modelling for the Biology of Cancer), Institut Curie, Research Center Orsay, CNRS UMR9187, INSERM U1196, Paris-Saclay University, Bât. 110, 91405, Orsay, France
| | - Victoria Birkedal
- Department of Chemistry and iNANO center, Aarhus University, Gustav Wieds Vej 14, 8000, Aarhus, Denmark
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21
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Lidberg KA, Annalora AJ, Jozic M, Elson DJ, Wang L, Bammler TK, Ramm S, Monteiro MB, Himmelfarb J, Marcus CB, Iversen PL, Kelly EJ. Antisense oligonucleotide development for the selective modulation of CYP3A5 in renal disease. Sci Rep 2021; 11:4722. [PMID: 33633318 PMCID: PMC7907328 DOI: 10.1038/s41598-021-84194-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 02/10/2021] [Indexed: 11/09/2022] Open
Abstract
CYP3A5 is the primary CYP3A subfamily enzyme expressed in the human kidney and its aberrant expression may contribute to a broad spectrum of renal disorders. Pharmacogenetic studies have reported inconsistent linkages between CYP3A5 expression and hypertension, however, most investigators have considered CYP3A5*1 as active and CYP3A5*3 as an inactive allele. Observations of gender specific differences in CYP3A5*3/*3 protein expression suggest additional complexity in gene regulation that may underpin an environmentally responsive role for CYP3A5 in renal function. Reconciliation of the molecular mechanism driving conditional restoration of functional CYP3A5*3 expression from alternatively spliced transcripts, and validation of a morpholino-based approach for selectively suppressing renal CYP3A5 expression, is the focus of this work. Morpholinos targeting a cryptic splice acceptor created by the CYP3A5*3 mutation in intron 3 rescued functional CYP3A5 expression in vitro, and salt-sensitive cellular mechanisms regulating splicing and conditional expression of CYP3A5*3 transcripts are reported. The potential for a G-quadruplex (G4) in intron 3 to mediate restored splicing to exon 4 in CYP3A5*3 transcripts was also investigated. Finally, a proximal tubule microphysiological system (PT-MPS) was used to evaluate the safety profile of morpholinos in proximal tubule epithelial cells, highlighting their potential as a therapeutic platform for the treatment of renal disease.
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Affiliation(s)
- Kevin A Lidberg
- Department of Pharmaceutics, University of Washington, Seattle, WA, USA
| | - Andrew J Annalora
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR, USA.
| | - Marija Jozic
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR, USA
| | - Daniel J Elson
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR, USA
| | - Lu Wang
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
| | - Theo K Bammler
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
| | - Susanne Ramm
- Victorian Centre for Functional Genomics, Peter MacCallum Cancer Centre, Melbourne, Australia
| | - Maria Beatriz Monteiro
- Depto Clinica Medica, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, São Paulo, Brazil
| | | | - Craig B Marcus
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR, USA
| | - Patrick L Iversen
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR, USA
| | - Edward J Kelly
- Department of Pharmaceutics, University of Washington, Seattle, WA, USA.
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22
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Marchand A, Beauvineau C, Teulade-Fichou MP, Zenobi R. Competition of Ligands and the 18-mer Binding Domain of the RHAU Helicase for G-Quadruplexes: Orthosteric or Allosteric Binding Mechanism? Chemistry 2021; 27:1113-1121. [PMID: 33617136 DOI: 10.1002/chem.202004040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 10/12/2020] [Indexed: 01/12/2023]
Abstract
Stabilizing the DNA and RNA structures known as G-quadruplexes (G4s) using specific ligands is a strategy that has been proposed to fight cancer. However, although G-quadruplex:ligand (G4:L) interactions have often been investigated, whether or not ligands are able to disrupt G-quadruplex:protein (G4:P) interactions remains poorly studied. In this study, using native mass spectrometry, we have investigated ternary G4:L:P complexes formed by G4s, some of the highest affinity ligands, and the binding domain of the RHAU helicase. Our results suggest that RHAU binds not only preferentially to parallel G4s, but also to free external G-quartets. We also found that, depending on the G4, ligands could prevent the binding of the peptide, either by direct competition for the binding sites (orthosteric inhibition) or by inducing conformational changes (allosteric inhibition). Notably, the ligand Cu-ttpy (ttpy=4'-tolyl-2,2':6',2''-terpyridine) induced a conformational change that increased the binding of the peptide. This study illustrates that it is important to not only characterize drug-target interactions, but also how the binding to other partners is affected.
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Affiliation(s)
- Adrien Marchand
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 3, 8093, Zürich, Switzerland
| | - Claire Beauvineau
- PSL Research University, CNRS-UMR 9187, INSERM U1196, Institut Curie, 91405, Orsay, France.,CNRS-UMR 9187, INSERM U1196, Université Paris Sud, Université Paris-Saclay, 91405, Orsay, France
| | - Marie-Paule Teulade-Fichou
- PSL Research University, CNRS-UMR 9187, INSERM U1196, Institut Curie, 91405, Orsay, France.,CNRS-UMR 9187, INSERM U1196, Université Paris Sud, Université Paris-Saclay, 91405, Orsay, France
| | - Renato Zenobi
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 3, 8093, Zürich, Switzerland
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23
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Liu NN, Ji L, Guo Q, Dai YX, Wu WQ, Guo HL, Lu KY, Li XM, Xi XG. Quantitative and real-time measurement of helicase-mediated intra-stranded G4 unfolding in bulk fluorescence stopped-flow assays. Anal Bioanal Chem 2020; 412:7395-7404. [PMID: 32851458 DOI: 10.1007/s00216-020-02875-3] [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: 07/04/2020] [Revised: 08/03/2020] [Accepted: 08/10/2020] [Indexed: 01/26/2023]
Abstract
G-Quadruplexes (G4s) are thermodynamically stable, compact, and poorly hydrated structures that pose a potent obstacle for chromosome replication and gene expression, and requiring resolution by helicases in a cell. Bulk stopped-flow fluorescence assays have provided many mechanistic insights into helicase-mediated duplex DNA unwinding. However, to date, detailed studies on intramolecular G-quadruplexes similar or comparable with those used for studying duplex DNA are still lacking. Here, we describe a method for the direct and quantitative measurement of helicase-mediated intramolecular G-quadruplex unfolding in real time. We designed a series of site-specific fluorescently double-labeled intramolecular G4s and screened appropriate substrates to characterize the helicase-mediated G4 unfolding. With the developed method, we determined, for the first time to our best knowledge, the unfolding and refolding constant of G4 (≈ 5 s-1), and other relative parameters under single-turnover experimental conditions in the presence of G4 traps. Our approach not only provides a new paradigm for characterizing helicase-mediated intramolecular G4 unfolding using stopped-flow assays but also offers a way to screen for inhibitors of G4 unfolding helicases as therapeutic drug targets. Graphical abstract.
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Affiliation(s)
- Na-Nv Liu
- College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Lei Ji
- College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Qian Guo
- College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Yang-Xue Dai
- College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Wen-Qiang Wu
- College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Hai-Lei Guo
- College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Ke-Yu Lu
- College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Xiao-Mei Li
- College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Xu-Guang Xi
- College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China. .,Laboratoire de Biologie et Pharmacologie Appliquée, Ecole Normale Supérieure de Cachan, Centre National de la Recherche Scientifique, Université Paris-Saclay, 61 Avenue du Président Wilson, 94235, Cachan, France.
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24
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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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25
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Bryan TM. G-Quadruplexes at Telomeres: Friend or Foe? Molecules 2020; 25:molecules25163686. [PMID: 32823549 PMCID: PMC7464828 DOI: 10.3390/molecules25163686] [Citation(s) in RCA: 85] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 08/09/2020] [Accepted: 08/10/2020] [Indexed: 12/28/2022] Open
Abstract
Telomeres are DNA-protein complexes that cap and protect the ends of linear chromosomes. In almost all species, telomeric DNA has a G/C strand bias, and the short tandem repeats of the G-rich strand have the capacity to form into secondary structures in vitro, such as four-stranded G-quadruplexes. This has long prompted speculation that G-quadruplexes play a positive role in telomere biology, resulting in selection for G-rich tandem telomere repeats during evolution. There is some evidence that G-quadruplexes at telomeres may play a protective capping role, at least in yeast, and that they may positively affect telomere maintenance by either the enzyme telomerase or by recombination-based mechanisms. On the other hand, G-quadruplex formation in telomeric DNA, as elsewhere in the genome, can form an impediment to DNA replication and a source of genome instability. This review summarizes recent evidence for the in vivo existence of G-quadruplexes at telomeres, with a focus on human telomeres, and highlights some of the many unanswered questions regarding the location, form, and functions of these structures.
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Affiliation(s)
- Tracy M Bryan
- Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW 2145, Australia
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26
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Zacheja T, Toth A, Harami GM, Yang Q, Schwindt E, Kovács M, Paeschke K, Burkovics P. Mgs1 protein supports genome stability via recognition of G-quadruplex DNA structures. FASEB J 2020; 34:12646-12662. [PMID: 32748509 DOI: 10.1096/fj.202000886r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 06/19/2020] [Accepted: 07/10/2020] [Indexed: 01/02/2023]
Abstract
The integrity of the genetic material is crucial for every organism. One intrinsic attack to genome stability is stalling of the replication fork which can result in DNA breakage. Several factors, such as DNA lesions or the formation of stable secondary structures (eg, G-quadruplexes) can lead to replication fork stalling. G-quadruplexes (G4s) are well-characterized stable secondary DNA structures that can form within specific single-stranded DNA sequence motifs and have been shown to block/pause the replication machinery. In most genomes several helicases have been described to regulate G4 unfolding to preserve genome integrity, however, different experiments raise the hypothesis that processing of G4s during DNA replication is more complex and requires additional, so far unknown, proteins. Here, we show that the Saccharomyces cerevisiae Mgs1 protein robustly binds to G4 structures in vitro and preferentially acts at regions with a strong potential to form G4 structures in vivo. Our results suggest that Mgs1 binds to G4-forming sites and has a role in the maintenance of genome integrity.
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Affiliation(s)
- Theresa Zacheja
- Department of Oncology, Hematology and Rheumatology, University Hospital Bonn, Bonn, Germany
| | - Agnes Toth
- Biological Research Centre, Institute of Genetics, Szeged, Hungary.,Doctoral School of Biology, Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Gabor M Harami
- ELTE-MTA Momentum Motor Enzymology Research Group, Department of Biochemistry, Eötvös Loránd University, Budapest, Hungary
| | - Qianlu Yang
- Department of Biochemistry, Biocenter, University of Wuerzburg, Wuerzburg, Germany.,Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, China
| | - Eike Schwindt
- Department of Oncology, Hematology and Rheumatology, University Hospital Bonn, Bonn, Germany
| | - Mihály Kovács
- ELTE-MTA Momentum Motor Enzymology Research Group, Department of Biochemistry, Eötvös Loránd University, Budapest, Hungary.,MTA-ELTE Motor Pharmacology Research Group, Department of Biochemistry, Eötvös Loránd University, Budapest, Hungary
| | - Katrin Paeschke
- Department of Oncology, Hematology and Rheumatology, University Hospital Bonn, Bonn, Germany.,Department of Biochemistry, Biocenter, University of Wuerzburg, Wuerzburg, Germany
| | - Peter Burkovics
- Biological Research Centre, Institute of Genetics, Szeged, Hungary
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27
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Dresser L, Hunter P, Yendybayeva F, Hargreaves AL, Howard JAL, Evans GJO, Leake MC, Quinn SD. Amyloid-β oligomerization monitored by single-molecule stepwise photobleaching. Methods 2020; 193:80-95. [PMID: 32544592 PMCID: PMC8336786 DOI: 10.1016/j.ymeth.2020.06.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 06/02/2020] [Accepted: 06/10/2020] [Indexed: 01/19/2023] Open
Abstract
Method enables investigation of amyloid-β oligomer stoichiometry without requiring extrinsic fluorescent probes. Uses single-molecule stepwise photobleaching in vitro. Unveils heterogeneity within populations of oligomers. Assays oligomer-induced dysregulation of intracellular Ca2+ homeostasis in living cells.
A major hallmark of Alzheimer’s disease is the misfolding and aggregation of the amyloid- β peptide (Aβ). While early research pointed towards large fibrillar- and plaque-like aggregates as being the most toxic species, recent evidence now implicates small soluble Aβ oligomers as being orders of magnitude more harmful. Techniques capable of characterizing oligomer stoichiometry and assembly are thus critical for a deeper understanding of the earliest stages of neurodegeneration and for rationally testing next-generation oligomer inhibitors. While the fluorescence response of extrinsic fluorescent probes such as Thioflavin-T have become workhorse tools for characterizing large Aβ aggregates in solution, it is widely accepted that these methods suffer from many important drawbacks, including an insensitivity to oligomeric species. Here, we integrate several biophysics techniques to gain new insight into oligomer formation at the single-molecule level. We showcase single-molecule stepwise photobleaching of fluorescent dye molecules as a powerful method to bypass many of the traditional limitations, and provide a step-by-step guide to implementing the technique in vitro. By collecting fluorescence emission from single Aβ(1–42) peptides labelled at the N-terminal position with HiLyte Fluor 555 via wide-field total internal reflection fluorescence (TIRF) imaging, we demonstrate how to characterize the number of peptides per single immobile oligomer and reveal heterogeneity within sample populations. Importantly, fluorescence emerging from Aβ oligomers cannot be easily investigated using diffraction-limited optical microscopy tools. To assay oligomer activity, we also demonstrate the implementation of another biophysical method involving the ratiometric imaging of Fura-2-AM loaded cells which quantifies the rate of oligomer-induced dysregulation of intracellular Ca2+ homeostasis. We anticipate that the integrated single-molecule biophysics approaches highlighted here will develop further and in principle may be extended to the investigation of other protein aggregation systems under controlled experimental conditions.
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Affiliation(s)
- Lara Dresser
- Department of Physics, University of York, Heslington YO10 5DD, UK
| | - Patrick Hunter
- Department of Physics, University of York, Heslington YO10 5DD, UK
| | | | - Alex L Hargreaves
- Department of Physics, University of York, Heslington YO10 5DD, UK; Department of Biology, University of York, Heslington YO10 5DD, UK
| | - Jamieson A L Howard
- Department of Physics, University of York, Heslington YO10 5DD, UK; Department of Biology, University of York, Heslington YO10 5DD, UK
| | - Gareth J O Evans
- Department of Biology, University of York, Heslington YO10 5DD, UK; York Biomedical Research Institute, University of York, Heslington YO10 5DD, UK
| | - Mark C Leake
- Department of Physics, University of York, Heslington YO10 5DD, UK; Department of Biology, University of York, Heslington YO10 5DD, UK; York Biomedical Research Institute, University of York, Heslington YO10 5DD, UK
| | - Steven D Quinn
- Department of Physics, University of York, Heslington YO10 5DD, UK; York Biomedical Research Institute, University of York, Heslington YO10 5DD, UK.
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28
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Frelih T, Wang B, Plavec J, Šket P. Pre-folded structures govern folding pathways of human telomeric G-quadruplexes. Nucleic Acids Res 2020; 48:2189-2197. [PMID: 31950178 PMCID: PMC7038944 DOI: 10.1093/nar/gkz1235] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 12/12/2019] [Accepted: 12/31/2019] [Indexed: 01/12/2023] Open
Abstract
Understanding the mechanism by which biological macromolecules fold into their functional native conformations represents a problem of fundamental interest. DNA oligonucleotides derived from human telomeric repeat d[TAGGG(TTAGGG)3] and d[TAGGG(TTAGGG)3TT] fold into G-quadruplexes through diverse steps. Varying the pH and temperature by the use of nuclear magnetic resonance and other methods enabled detection of pre-folded structures that exist in solution before completely formed G-quadruplexes upon addition of cations. Pre-folded structures are in general hard to detect, however their knowledge is crucial to set up folding pathways into final structure since they are believed to be a starting point. Unexpectedly well-defined pre-folded structures composed of base triples for both oligonucleotides were detected at certain pH and temperature. These kinds of structures were up to now only hypothesized as intermediates in the folding process. All revealed pre-folded structures irrespective of the pH and temperature exhibited one common structural feature that could govern folding process.
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Affiliation(s)
- Tjaša Frelih
- Slovenian NMR Center, National Institute of Chemistry, Ljubljana 1000, Slovenia
| | - Baifan Wang
- Slovenian NMR Center, National Institute of Chemistry, Ljubljana 1000, Slovenia
| | - Janez Plavec
- Slovenian NMR Center, National Institute of Chemistry, Ljubljana 1000, Slovenia
- EN-FIST Center of Excellence, Ljubljana 1000, Slovenia
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana 1000, Slovenia
- Correspondence may also be addressed to Janez Plavec. Tel: +386 1 476 0353; Fax: +386 1 476 0300;
| | - Primož Šket
- Slovenian NMR Center, National Institute of Chemistry, Ljubljana 1000, Slovenia
- To whom correspondence should be addressed. Tel: +386 1 476 0223; Fax: +386 1 476 0300;
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29
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Marchand A, Czar MF, Eggel EN, Kaeslin J, Zenobi R. Studying biomolecular folding and binding using temperature-jump mass spectrometry. Nat Commun 2020; 11:566. [PMID: 31992698 PMCID: PMC6987177 DOI: 10.1038/s41467-019-14179-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 12/19/2019] [Indexed: 01/14/2023] Open
Abstract
Characterizing folding and complex formation of biomolecules provides a view into their thermodynamics, kinetics and folding pathways. Deciphering kinetic intermediates is particularly important because they can often be targeted by drugs. The key advantage of native mass spectrometry over conventional methods that monitor a single observable is its ability to identify and quantify coexisting species. Here, we show the design of a temperature-jump electrospray source for mass spectrometry that allows one to perform fast kinetics experiments (0.16-32 s) at different temperatures (10-90 °C). The setup allows recording of both folding and unfolding kinetics by using temperature jumps from high to low, and low to high, temperatures. Six biological systems, ranging from peptides to proteins to DNA complexes, exemplify the use of this device. Using temperature-dependent experiments, the folding and unfolding of a DNA triplex are studied, providing detailed information on its thermodynamics and kinetics.
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Affiliation(s)
- Adrien Marchand
- Department of Chemistry and Applied Biosciences, ETH Zurich, CH-8093, Zurich, Switzerland
| | - Martin F Czar
- Department of Chemistry and Applied Biosciences, ETH Zurich, CH-8093, Zurich, Switzerland
| | - Elija N Eggel
- Department of Chemistry and Applied Biosciences, ETH Zurich, CH-8093, Zurich, Switzerland
| | - Jérôme Kaeslin
- Department of Chemistry and Applied Biosciences, ETH Zurich, CH-8093, Zurich, Switzerland
| | - Renato Zenobi
- Department of Chemistry and Applied Biosciences, ETH Zurich, CH-8093, Zurich, Switzerland.
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30
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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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31
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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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32
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Sneaking Out for Happy Hour: Yeast-Based Approaches to Explore and Modulate Immune Response and Immune Evasion. Genes (Basel) 2019; 10:genes10090667. [PMID: 31480411 PMCID: PMC6770942 DOI: 10.3390/genes10090667] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 08/26/2019] [Accepted: 08/28/2019] [Indexed: 01/09/2023] Open
Abstract
Many pathogens (virus, bacteria, fungi, or parasites) have developed a wide variety of mechanisms to evade their host immune system. The budding yeast Saccharomyces cerevisiae has successfully been used to decipher some of these immune evasion strategies. This includes the cis-acting mechanism that limits the expression of the oncogenic Epstein–Barr virus (EBV)-encoded EBNA1 and thus of antigenic peptides derived from this essential but highly antigenic viral protein. Studies based on budding yeast have also revealed the molecular bases of epigenetic switching or recombination underlying the silencing of all except one members of extended families of genes that encode closely related and highly antigenic surface proteins. This mechanism is exploited by several parasites (that include pathogens such as Plasmodium, Trypanosoma, Candida, or Pneumocystis) to alternate their surface antigens, thereby evading the immune system. Yeast can itself be a pathogen, and pathogenic fungi such as Candida albicans, which is phylogenetically very close to S. cerevisiae, have developed stealthiness strategies that include changes in their cell wall composition, or epitope-masking, to control production or exposure of highly antigenic but essential polysaccharides in their cell wall. Finally, due to the high antigenicity of its cell wall, yeast has been opportunistically exploited to create adjuvants and vectors for vaccination.
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33
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Ma G, Yu Z, Zhou W, Li Y, Fan L, Li X. Investigation of Na+ and K+ Competitively Binding with a G-Quadruplex and Discovery of a Stable K+–Na+-Quadruplex. J Phys Chem B 2019; 123:5405-5411. [DOI: 10.1021/acs.jpcb.9b02823] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Ge Ma
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Ze Yu
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Wei Zhou
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Yunchao Li
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Louzhen Fan
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Xiaohong Li
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
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34
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Arns L, Knop JM, Patra S, Anders C, Winter R. Single-molecule insights into the temperature and pressure dependent conformational dynamics of nucleic acids in the presence of crowders and osmolytes. Biophys Chem 2019; 251:106190. [PMID: 31146215 DOI: 10.1016/j.bpc.2019.106190] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 05/20/2019] [Accepted: 05/20/2019] [Indexed: 11/19/2022]
Abstract
In this review we discuss results from temperature and pressure dependent single-molecule Förster resonance energy transfer (smFRET) studies on nucleic acids in the presence of macromolecular crowders and organic osmolytes. As representative examples, we have chosen fragments of both DNAs and RNAs, i.e., a synthetic DNA hairpin, a human telomeric G-quadruplex and the microROSE RNA hairpin. To mimic the effects of intracellular components, our studies include the macromolecular crowding agent Ficoll, a copolymer of sucrose and epichlorohydrin, and the organic osmolytes trimethylamine N-oxide, urea and glycine as well as natural occurring osmolyte mixtures from deep sea organisms. Furthermore, the impact of mutations in an RNA sequence on the conformational dynamics is examined. Different from proteins, the effects of the osmolytes and crowding agents seem to strongly dependent on the structure and chemical make-up of the nucleic acid.
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Affiliation(s)
- Loana Arns
- TU Dortmund University, Faculty of Chemistry and Chemical Biology, Physical Chemistry, Otto-Hahn-Str. 4a, D-44227 Dortmund, Germany
| | - Jim-Marcel Knop
- TU Dortmund University, Faculty of Chemistry and Chemical Biology, Physical Chemistry, Otto-Hahn-Str. 4a, D-44227 Dortmund, Germany
| | - Satyajit Patra
- Aix Marseille Université, CNRS, Centralle Marseille, Institut Fresnel, F-13013 Marseille, France
| | - Christian Anders
- TU Dortmund University, Faculty of Chemistry and Chemical Biology, Physical Chemistry, Otto-Hahn-Str. 4a, D-44227 Dortmund, Germany
| | - Roland Winter
- TU Dortmund University, Faculty of Chemistry and Chemical Biology, Physical Chemistry, Otto-Hahn-Str. 4a, D-44227 Dortmund, Germany.
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35
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Ge F, Wang Y, Li H, Zhang R, Wang X, Li Q, Liang Z, Yang L. Plant-GQ: An Integrative Database of G-Quadruplex in Plant. J Comput Biol 2019; 26:1013-1019. [PMID: 30958698 DOI: 10.1089/cmb.2019.0010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
G-quadruplex (G-Q) is advanced DNA or RNA secondary structures frequently found in plant and involved in important biological processes such as transcription, translation, and telomere maintenance. Although some databases and tools were developed for predicting and studying G-Q, none of them was for plant. With the development of next-generation sequencing technology, a large number of plant genomes have been assembled and annotated to provide opportunities for mining G-Q. Plant G-quadruplex database (Plant-GQ) was constructed for predicting G-Q in 195 plants. It has a total of 626,341,645 predicted G-Qs. The database contains four major parts: Search, Tools, JBrowse, and Download. Not only G-Q information but also online forecasting tool can be retrieved and obtained from Plant-GQ. It can also browse and analyze G-Q information by JBrowse in a graph visualization interface. Considering the key role of G-Q in plant, this database will play an important status in the study of the structure, function, and biological relevance of G-Q in plant.
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Affiliation(s)
- Fangfang Ge
- Agricultural Big-Data Research Center and College of Plant Protection, Shandong Agricultural University, Taian, China
| | - Yi Wang
- Beijing Key Laboratory of Grape Science and Enology and Key Laboratory of Plant Resource, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Huayang Li
- Agricultural Big-Data Research Center and College of Plant Protection, Shandong Agricultural University, Taian, China
| | - Rui Zhang
- Agricultural Big-Data Research Center and College of Plant Protection, Shandong Agricultural University, Taian, China
| | - Xiaotong Wang
- Agricultural Big-Data Research Center and College of Plant Protection, Shandong Agricultural University, Taian, China
| | - Qingyun Li
- Agricultural Big-Data Research Center and College of Plant Protection, Shandong Agricultural University, Taian, China
| | - Zhenchang Liang
- Beijing Key Laboratory of Grape Science and Enology and Key Laboratory of Plant Resource, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Long Yang
- Agricultural Big-Data Research Center and College of Plant Protection, Shandong Agricultural University, Taian, China
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36
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Bian Y, Song F, Cao Z, Zhao L, Yu J, Guo X, Wang J. Fast-Folding Pathways of the Thrombin-Binding Aptamer G-Quadruplex Revealed by a Markov State Model. Biophys J 2019; 114:1529-1538. [PMID: 29642024 DOI: 10.1016/j.bpj.2018.02.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 02/12/2018] [Accepted: 02/20/2018] [Indexed: 12/31/2022] Open
Abstract
G-quadruplex structures participate in many important cellular processes. For a better understanding of their functions, knowledge of the mechanism by which they fold into the functional native structures is necessary. In this work, we studied the folding process of the thrombin-binding aptamer G-quadruplex. Enabled by a computational paradigm that couples an advanced sampling method and a Markov state model, four folding intermediates were identified, including an antiparallel G-hairpin, two G-triplex structures, and a double-hairpin conformation. Likewise, a misfolded structure with a nonnative distribution of syn/anti guanines was also observed. Based on these states, a transition path analysis revealed three fast-folding pathways, along which the thrombin-binding aptamer would fold to the native state directly, with no evidence of potential nonnative competing conformations. The results also showed that the TGT-loop plays an important role in the folding process. The findings of this research may provide general insight about the folding of other G-quadruplex structures.
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Affiliation(s)
- Yunqiang Bian
- Shandong Provincial Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou, China.
| | - Feng Song
- Shandong Provincial Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou, China
| | - Zanxia Cao
- Department of Physics, Dezhou University, Dezhou, China
| | - Liling Zhao
- Department of Physics, Dezhou University, Dezhou, China
| | - Jiafeng Yu
- Shandong Provincial Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou, China
| | - Xinlu Guo
- Wuxi Vocational Institute of Commerce, Wuxi, China; Taihu University of Wuxi, Wuxi, China
| | - Jihua Wang
- Shandong Provincial Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou, China; Department of Physics, Dezhou University, Dezhou, China.
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37
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Extreme mechanical diversity of human telomeric DNA revealed by fluorescence-force spectroscopy. Proc Natl Acad Sci U S A 2019; 116:8350-8359. [PMID: 30944218 DOI: 10.1073/pnas.1815162116] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
G-quadruplexes (GQs) can adopt diverse structures and are functionally implicated in transcription, replication, translation, and maintenance of telomere. Their conformational diversity under physiological levels of mechanical stress, however, is poorly understood. We used single-molecule fluorescence-force spectroscopy that combines fluorescence resonance energy transfer with optical tweezers to measure human telomeric sequences under tension. Abrupt GQ unfolding with K+ in solution occurred at as many as four discrete levels of force. Added to an ultrastable state and a gradually unfolding state, there were six mechanically distinct structures. Extreme mechanical diversity was also observed with Na+, although GQs were mechanically weaker. Our ability to detect small conformational changes at low forces enabled the determination of refolding forces of about 2 pN. Refolding was rapid and stochastically redistributed molecules to mechanically distinct states. A single guanine-to-thymine substitution mutant required much higher ion concentrations to display GQ-like unfolding and refolded via intermediates, contrary to the wild type. Contradicting an earlier proposal, truncation to three hexanucleotide repeats resulted in a single-stranded DNA-like mechanical behavior under all conditions, indicating that at least four repeats are required to form mechanically stable structures.
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38
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Abstract
Circular dichroism and stopped-flow UV spectroscopies were used to investigate the thermodynamic stability and the folding pathway of d[TGAG3TG3TAG3TG3TA2] at 25 °C in solutions containing 25 mM KCl. Under these conditions the oligonucleotide adopts a thermally stable, all-parallel G-quadruplex topography containing three stacked quartets. K+-induced folding shows three resolved relaxation times, each with distinctive spectral changes. Folding is complete within 200 s. These data indicate a folding pathway that involves at least two populated intermediates, one of which seems to be an antiparallel structure that rearranges to the final all-parallel conformation. Molecular dynamics reveals a stereochemically plausible folding pathway that does not involve complete unfolding of the intermediate. The rate of unfolding was determined using complementary DNA to trap transiently unfolded states to form a stable duplex. As assessed by 1D-1H NMR and fluorescence spectroscopy, unfolding is extremely slow with only one observable rate-limiting relaxation time.
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39
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Knop JM, Patra S, Harish B, Royer CA, Winter R. The Deep Sea Osmolyte Trimethylamine N-Oxide and Macromolecular Crowders Rescue the Antiparallel Conformation of the Human Telomeric G-Quadruplex from Urea and Pressure Stress. Chemistry 2018; 24:14346-14351. [PMID: 29993151 DOI: 10.1002/chem.201802444] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 07/04/2018] [Indexed: 11/10/2022]
Abstract
Organisms are thriving in the deep sea at pressures up to the 1 kbar level, which imposes severe stress on the conformational dynamics and stability of their biomolecules. The impact of osmolytes and macromolecular crowders, mimicking intracellular conditions, on the effect of pressure on the conformational dynamics of a human telomeric G-quadruplex (G4) DNA is explored in this study employing single-molecule Förster resonance energy transfer (FRET) experiments. In neat buffer, pressurization favors the parallel/hybrid state of the G4-DNA over the antiparallel conformation at ≈400 bar, finally leading to unfolding beyond 1000 bar. High-pressure NMR data support these findings. The folded topological conformers have different solvent accessible surface areas and cavity volumes, leading to different volumetric properties and hence pressure stabilities. The deep-sea osmolyte trimethylamine N-oxide (TMAO) and macromolecular crowding agents are able to effectively rescue the G4-DNA from unfolding in the whole pressure range encountered on Earth.
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Affiliation(s)
- Jim-Marcel Knop
- Physikalische Chemie I-Biophysikalische Chemie, Fakultät für Chemie und Chemische Biologie, TU Dortmund, Otto-Hahn Str. 4a, 44227, Dortmund, Germany
| | - Satyajit Patra
- Physikalische Chemie I-Biophysikalische Chemie, Fakultät für Chemie und Chemische Biologie, TU Dortmund, Otto-Hahn Str. 4a, 44227, Dortmund, Germany
| | - Balasubramanian Harish
- Center for Biotechnology & Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, 12180, NY, USA
| | - Catherine A Royer
- Center for Biotechnology & Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, 12180, NY, USA
| | - Roland Winter
- Physikalische Chemie I-Biophysikalische Chemie, Fakultät für Chemie und Chemische Biologie, TU Dortmund, Otto-Hahn Str. 4a, 44227, Dortmund, Germany
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40
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Fijen C, Montón Silva A, Hochkoeppler A, Hohlbein J. A single-molecule FRET sensor for monitoring DNA synthesis in real time. Phys Chem Chem Phys 2018; 19:4222-4230. [PMID: 28116374 DOI: 10.1039/c6cp05919h] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We developed a versatile DNA assay and framework for monitoring polymerization of DNA in real time and at the single-molecule level. The assay consists of an acceptor labelled DNA primer annealed to a DNA template that is labelled on its single stranded, downstream overhang with a donor fluorophore. Upon extension of the primer using a DNA polymerase, the overhang of the template alters its conformation from a random coil to the canonical structure of double stranded DNA. This conformational change increases the distance between the donor and the acceptor fluorophore and can be detected as a decrease in the Förster resonance energy transfer (FRET) efficiency between both fluorophores. Remarkably, the DNA assay does not require any modification of the DNA polymerase and albeit the simple and robust spectroscopic readout facilitates measurements even with conventional fluorimeters or stopped-flow equipment, single-molecule FRET provides additional access to parameters such as the processivity of DNA synthesis and, for one of the three DNA polymerases tested, the detection of binding and dissociation of the DNA polymerase to DNA. We furthermore demonstrate that primer extensions by a single base can be resolved.
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Affiliation(s)
- Carel Fijen
- Laboratory of Biophysics, Wageningen University and Research, Stippeneng 4, Wageningen, 6708 WE, The Netherlands.
| | - Alejandro Montón Silva
- Laboratory of Biophysics, Wageningen University and Research, Stippeneng 4, Wageningen, 6708 WE, The Netherlands. and Department of Pharmacy and Biotechnology, University of Bologna, Viale Risorgimento 4, Bologna, 40136, Italy
| | - Alejandro Hochkoeppler
- Department of Pharmacy and Biotechnology, University of Bologna, Viale Risorgimento 4, Bologna, 40136, Italy
| | - Johannes Hohlbein
- Laboratory of Biophysics, Wageningen University and Research, Stippeneng 4, Wageningen, 6708 WE, The Netherlands. and Microspectroscopy Centre, Wageningen University and Research, Stippeneng 4, Wageningen, 6708 WE, The Netherlands
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41
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Tucker BA, Hudson JS, Ding L, Lewis E, Sheardy RD, Kharlampieva E, Graves D. Stability of the Na + Form of the Human Telomeric G-Quadruplex: Role of Adenines in Stabilizing G-Quadruplex Structure. ACS OMEGA 2018; 3:844-855. [PMID: 30023791 PMCID: PMC6045420 DOI: 10.1021/acsomega.7b01649] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 01/09/2018] [Indexed: 06/08/2023]
Abstract
G-quadruplexes are higher order DNA structures that play significant roles in gene transcription and telomeric maintenance. The formation and stability of the G-quadruplex structures are under thermodynamic control and may be of biological significance for regulatory function of cellular processes. Here, we report the structural influence and energetic contributions of the adenine bases in the loop sequences that flank G-repeats in human telomeric DNA sequence. Spectroscopic and calorimetric techniques are used to measure the thermal stability and thermodynamic contributions to the stability of human telomeric G-quadruplexes that have been designed with systematic changes of A to T throughout the telomeric sequence. These studies demonstrate that the thermal stability of the G-quadruplex structure is directly related to the number and position of the adenines that are present in the telomeric sequence. The melting temperature (Tm) was reduced from 59 °C for the wild-type sequence to 47 °C for the sequence where all four adenines were replaced with thymines (0123TTT). Furthermore, the enthalpy required for transitioning from the folded to unfolded G-quadruplex structure was reduced by 15 kcal/mol when the adenines were replaced with thymines (37 kcal/mol for the wild-type telomeric sequence reduced to 22 kcal/mol for the sequence where all four adenines were replaced with thymines (0123TTT)). The circular dichroism melting studies for G-quadruplex sequences having a single A to T change showed significantly sloping pretransition baselines and their differential scanning calorimetry (DSC) thermograms revealed biphasic melting profiles. In contrast, the deoxyoligonucleotides having sequences with two or more A to T changes did not exhibit sloping baselines or biphasic DSC thermograms. We attribute the biphasic unfolding profile and reduction in the enthalpy of unfolding to the energetic contributions of adenine hydrogen bonding within the loops as well as the adenine stacking to the G-tetrads of the G-quadruplex structure.
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Affiliation(s)
- Brenna A. Tucker
- Department
of Chemistry, Department of Biochemistry and Molecular Genetics, and Comprehensive
Cancer Center, University of Alabama at
Birmingham, Birmingham, Alabama 35294, United States
| | - Jason S. Hudson
- Department
of Chemistry, Department of Biochemistry and Molecular Genetics, and Comprehensive
Cancer Center, University of Alabama at
Birmingham, Birmingham, Alabama 35294, United States
| | - Lei Ding
- Department
of Chemistry, Department of Biochemistry and Molecular Genetics, and Comprehensive
Cancer Center, University of Alabama at
Birmingham, Birmingham, Alabama 35294, United States
| | - Edwin Lewis
- Department
of Chemistry, Mississippi State University, Mississippi, Mississippi
State 39762, United
States
| | - Richard D. Sheardy
- Department
of Chemistry & Biochemistry, Texas Women’s
University, Denton, Texas 782042, United States
| | - Eugenia Kharlampieva
- Department
of Chemistry, Department of Biochemistry and Molecular Genetics, and Comprehensive
Cancer Center, University of Alabama at
Birmingham, Birmingham, Alabama 35294, United States
| | - David Graves
- Department
of Chemistry, Department of Biochemistry and Molecular Genetics, and Comprehensive
Cancer Center, University of Alabama at
Birmingham, Birmingham, Alabama 35294, United States
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42
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Lee HT, Bose A, Lee CY, Opresko PL, Myong S. Molecular mechanisms by which oxidative DNA damage promotes telomerase activity. Nucleic Acids Res 2017; 45:11752-11765. [PMID: 28981887 PMCID: PMC5714237 DOI: 10.1093/nar/gkx789] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 09/14/2017] [Indexed: 11/13/2022] Open
Abstract
Telomeres are highly susceptible to oxidative DNA damage, which if left unrepaired can lead to dysregulation of telomere length homeostasis. Here we employed single molecule FRET, single molecule pull-down and biochemical analysis to investigate how the most common oxidative DNA lesions, 8-oxoguanine (8oxoG) and thymine glycol (Tg), regulate the structural properties of telomeric DNA and telomerase extension activity. In contrast to 8oxoG which disrupts the telomeric DNA structure, Tg exhibits substantially reduced perturbation of G-quadruplex folding. As a result, 8oxoG induces high accessibility, whereas Tg retains limited accessibility, of telomeric G-quadruplex DNA to complementary single stranded DNA and to telomere binding protein POT1. Surprisingly, the Tg lesion stimulates telomerase loading and activity to a similar degree as an 8oxoG lesion. We demonstrate that this unexpected stimulation arises from Tg-induced conformational alterations and dynamics in telomeric DNA. Despite impacting structure by different mechanisms, both 8oxoG and Tg enhance telomerase binding and extension activity to the same degree, potentially contributing to oncogenesis.
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Affiliation(s)
- Hui-Ting Lee
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Arindam Bose
- Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health and UPMC Hillman Cancer Center, Pittsburgh, PA 15261, USA
| | - Chun-Ying Lee
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Patricia L Opresko
- Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health and UPMC Hillman Cancer Center, Pittsburgh, PA 15261, USA
| | - Sua Myong
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD, 21218, USA.,Physics Frontier Center (Center for Physics of Living Cells), University of Illinois, 1110 W. Green St., Urbana, IL 61801, USA
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43
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Investigation of 'Head-to-Tail'-Connected Oligoaryl N,O-Ligands as Recognition Motifs for Cancer-Relevant G-Quadruplexes. Molecules 2017; 22:molecules22122160. [PMID: 29210998 PMCID: PMC6149995 DOI: 10.3390/molecules22122160] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 11/22/2017] [Accepted: 12/02/2017] [Indexed: 12/11/2022] Open
Abstract
Oligomeric compounds, constituted of consecutive N,O-heteroaromatic rings, introduce useful and tunable properties as alternative ligands for biomolecular recognition. In this study, we have explored a synthetic scheme relying on Van Leusen oxazole formation, in conjunction with C–H activation of the formed oxazoles and their subsequent C–C cross-coupling to 2-bromopyridines in order to assemble a library of variable-length, ‘head-to-tail’-connected, pyridyl-oxazole ligands. Through investigation of the interaction of the three longer ligands (5-mer, 6-mer, 7-mer) with cancer-relevant G-quadruplex structures (human telomeric/22AG and c-Myc oncogene promoter/Myc2345-Pu22), the asymmetric pyridyl-oxazole motif has been demonstrated to be a prominent recognition element for G-quadruplexes. Fluorescence titrations reveal excellent binding affinities of the 7-mer and 6-mer for a Na+-induced antiparallel 22AG G-quadruplex (KD = 0.6 × 10−7 M−1 and 0.8 × 10−7 M−1, respectively), and satisfactory (albeit lower) affinities for the 22AG/K+ and Myc2345-Pu22/K+ G-quadruplexes. All ligands tested exhibit substantial selectivity for G-quadruplex versus duplex (ds26) DNA, as evidenced by competitive Förster resonance energy transfer (FRET) melting assays. Additionally, the 7-mer and 6-mer are capable of promoting a sharp morphology transition of 22AG/K+ G-quadruplex.
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44
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Hou XM, Fu YB, Wu WQ, Wang L, Teng FY, Xie P, Wang PY, Xi XG. Involvement of G-triplex and G-hairpin in the multi-pathway folding of human telomeric G-quadruplex. Nucleic Acids Res 2017; 45:11401-11412. [PMID: 28977514 PMCID: PMC5737514 DOI: 10.1093/nar/gkx766] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2017] [Accepted: 08/22/2017] [Indexed: 01/07/2023] Open
Abstract
G-quadruplex (G4) can be formed by G-rich DNA sequences that are widely distributed throughout the human genome. Although G-triplex and G-hairpin have been proposed as G4 folding intermediates, their formation still requires further investigation by experiments. Here, we employed single-molecule FRET to characterize the folding dynamics of G4 from human telomeric sequence. First, we observed four states during G4 folding initially assigned to be anti-parallel G4, G-triplex, G-hairpin and unfolded ssDNA. Then we constructed putative intra-strand G-triplex, G-hairpin structures and confirmed their existences in both NaCl and KCl. Further studies revealed those structures are going through dynamic transitions between different states and show relatively weak dependence on cations, unlike G4. Based on those results and molecular dynamics simulations, we proposed a multi-pathway folding mechanism for human telomeric G4. The present work may shed new light on our current understanding about the existence and stability of G4 intermediate states.
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Affiliation(s)
- Xi-Miao Hou
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Yi-Ben Fu
- Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Wen-Qiang Wu
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Lei Wang
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Fang-Yuan Teng
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Ping Xie
- Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Peng-Ye Wang
- Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Xu-Guang Xi
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China.,Laboratoire de Biologie et Pharmacologie Appliquée, Ecole Normale Supérieure de Cachan, Centre National de la Recherche Scientifique, 61 Avenue du Président Wilson, 94235 Cachan, France
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45
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Debnath M, Ghosh S, Chauhan A, Paul R, Bhattacharyya K, Dash J. Preferential targeting of i-motifs and G-quadruplexes by small molecules. Chem Sci 2017; 8:7448-7456. [PMID: 29163897 PMCID: PMC5674183 DOI: 10.1039/c7sc02693e] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 09/07/2017] [Indexed: 01/01/2023] Open
Abstract
i-Motifs and G-quadruplexes are dynamic nucleic acid secondary structures, which are believed to play key roles in gene expression. We herein report two peptidomimetic ligands (PBP1 and PBP2) that selectively target i-motifs and G-quadruplexes over double-stranded DNA. These peptidomimetics, regioisomeric with respect to the position of triazole/prolinamide motifs, have been synthesized using a modular method involving Cu(i)-catalyzed azide and alkyne cycloaddition. The para-isomer, PBP1 exhibits high selectivity for i-motifs while the meta-isomer PBP2 binds selectively to G-quadruplex structures. Interestingly, these ligands have the ability to induce G-quadruplex or i-motif structures from the unstructured single-stranded DNA conformations, as observed using single molecule Förster resonance energy transfer (smFRET) studies. The quantitative real-time polymerase chain reaction (qRT-PCR), western blot, and dual-luciferase assays indicate that PBP1 upregulates and PBP2 downregulates BCL-2 gene expression in cancer cells.
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Affiliation(s)
- Manish Debnath
- Department of Organic Chemistry , Indian Association for the Cultivation of Science , Jadavpur , Kolkata-700032 , India .
| | - Shirsendu Ghosh
- Department of Physical Chemistry , Indian Association for the Cultivation of Science , Jadavpur , Kolkata-700032 , India
| | - Ajay Chauhan
- Department of Organic Chemistry , Indian Association for the Cultivation of Science , Jadavpur , Kolkata-700032 , India .
| | - Rakesh Paul
- Department of Organic Chemistry , Indian Association for the Cultivation of Science , Jadavpur , Kolkata-700032 , India .
| | - Kankan Bhattacharyya
- Department of Physical Chemistry , Indian Association for the Cultivation of Science , Jadavpur , Kolkata-700032 , India
| | - Jyotirmayee Dash
- Department of Organic Chemistry , Indian Association for the Cultivation of Science , Jadavpur , Kolkata-700032 , India .
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46
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Dvořáková Z, Vorlíčková M, Renčiuk D. Spectroscopic insights into quadruplexes of five-repeat telomere DNA sequences upon G-block damage. Biochim Biophys Acta Gen Subj 2017; 1861:2750-2757. [DOI: 10.1016/j.bbagen.2017.07.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 06/16/2017] [Accepted: 07/24/2017] [Indexed: 11/26/2022]
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47
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Kejnovská I, Bednárová K, Renciuk D, Dvoráková Z, Školáková P, Trantírek L, Fiala R, Vorlícková M, Sagi J. Clustered abasic lesions profoundly change the structure and stability of human telomeric G-quadruplexes. Nucleic Acids Res 2017; 45:4294-4305. [PMID: 28369584 PMCID: PMC5416849 DOI: 10.1093/nar/gkx191] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 03/21/2017] [Indexed: 01/02/2023] Open
Abstract
Ionizing radiation produces clustered damage to DNA which is difficult to repair and thus more harmful than single lesions. Clustered lesions have only been investigated in dsDNA models. Introducing the term 'clustered damage to G-quadruplexes' we report here on the structural effects of multiple tetrahydrofuranyl abasic sites replacing loop adenines (A/AP) and tetrad guanines (G/AP) in quadruplexes formed by the human telomere d[AG3(TTAG3)3] (htel-22) and d[TAG3(TTAG3)3TT] (htel-25) in K+ solutions. Single to triple A/APs increased the population of parallel strands in their structures by stabilizing propeller type loops, shifting the antiparallel htel-22 into hybrid or parallel quadruplexes. In htel-25, the G/APs inhibited the formation of parallel strands and these adopted antiparallel topologies. Clustered G/AP and A/APs reduced the thermal stability of the wild-type htel-25. Depending on position, A/APs diminished or intensified the damaging effect of the G/APs. Taken together, clustered lesions can disrupt the topology and stability of the htel quadruplexes and restrict their conformational space. These in vitro results suggest that formation of clustered lesions in the chromosome capping structure can result in the unfolding of existing G-quadruplexes which can lead to telomere shortening.
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Affiliation(s)
- Iva Kejnovská
- Institute of Biophysics, Czech Academy of Sciences, v.v.i., Královopolská 135, CZ-612 65 Brno, Czech Republic
| | - Klára Bednárová
- Institute of Biophysics, Czech Academy of Sciences, v.v.i., Královopolská 135, CZ-612 65 Brno, Czech Republic
| | - Daniel Renciuk
- Institute of Biophysics, Czech Academy of Sciences, v.v.i., Královopolská 135, CZ-612 65 Brno, Czech Republic
| | - Zuzana Dvoráková
- Institute of Biophysics, Czech Academy of Sciences, v.v.i., Královopolská 135, CZ-612 65 Brno, Czech Republic
| | - Petra Školáková
- Institute of Biophysics, Czech Academy of Sciences, v.v.i., Královopolská 135, CZ-612 65 Brno, Czech Republic
| | - Lukáš Trantírek
- CEITEC-Central European Institute of Technology, Masaryk University, Kamenice 5, CZ-625 00 Brno, Czech Republic
| | - Radovan Fiala
- CEITEC-Central European Institute of Technology, Masaryk University, Kamenice 5, CZ-625 00 Brno, Czech Republic
| | - Michaela Vorlícková
- Institute of Biophysics, Czech Academy of Sciences, v.v.i., Královopolská 135, CZ-612 65 Brno, Czech Republic
| | - Janos Sagi
- Rimstone Laboratory, RLI, Carlsbad, CA 92010, USA
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48
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Effects of monovalent cations on folding kinetics of G-quadruplexes. Biosci Rep 2017; 37:BSR20170771. [PMID: 28588052 PMCID: PMC5567087 DOI: 10.1042/bsr20170771] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 06/02/2017] [Accepted: 06/06/2017] [Indexed: 01/29/2023] Open
Abstract
G-quadruplexes are special structures existing at the ends of human telomeres,
the folding kinetics of which are essential for their functions, such as in the
maintenance of genome stability and the protection of chromosome ends. In the
present study, we investigated the folding kinetics of G-quadruplex in different
monovalent cation environments and determined the detailed kinetic parameters
for Na+- and K+-induced G-quadruplex folding, and for its
structural transition from the basket-type Na+ form to the
hybrid-type K+ form. More interestingly, although Li+ was
often used in previous studies of G-quadruplex folding as a control ion supposed
to have no effect, we have found that Li+ can actually influence the
folding kinetics of both Na+- and K+-induced
G-quadruplexes significantly and in different ways, by changing the folding
fraction of Na+-induced G-quadruplexes and greatly increasing the
folding rates of K+-induced G-quadruplexes. The present study may
shed new light on the roles of monovalent cations in G-quadruplex folding and
should be useful for further studies of the underlying folding mechanism.
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49
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Griffin WC, Gao J, Byrd AK, Chib S, Raney KD. A biochemical and biophysical model of G-quadruplex DNA recognition by positive coactivator of transcription 4. J Biol Chem 2017; 292:9567-9582. [PMID: 28416612 DOI: 10.1074/jbc.m117.776211] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 04/14/2017] [Indexed: 12/22/2022] Open
Abstract
DNA sequences that are guanine-rich have received considerable attention because of their potential to fold into a secondary, four-stranded DNA structure termed G-quadruplex (G4), which has been implicated in genomic instability and some human diseases. We have previously identified positive coactivator of transcription (PC4), a single-stranded DNA (ssDNA)-binding protein, as a novel G4 interactor. Here, to expand on these previous observations, we biochemically and biophysically characterized the interaction between PC4 and G4DNA. PC4 can bind alternative G4DNA topologies with a low nanomolar Kd value of ∼2 nm, similar to that observed for ssDNA. In consideration of the different structural features between G4DNA and ssDNA, these binding data indicated that PC4 can interact with G4DNA in a manner distinct from ssDNA. The stoichiometry of the PC4-G4 complex was 1:1 for PC4 dimer:G4 substrate. PC4 did not enhance the rate of folding of G4DNA, and formation of the PC4-G4DNA complex did not result in unfolding of the G4DNA structure. We assembled a G4DNA structure flanked by duplex DNA. We find that PC4 can interact with this G4DNA, as well as the complementary C-rich strand. Molecular docking simulations and DNA footprinting experiments suggest a model where a PC4 dimer accommodates the DNA with one monomer on the G4 strand and the second monomer bound to the C-rich strand. Collectively, these data provide a novel mode of PC4 binding to a DNA secondary structure that remains within the framework of the model for binding to ssDNA. Additionally, consideration of the PC4-G4DNA interaction could provide insight into the biological functions of PC4, which remain incompletely understood.
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Affiliation(s)
- Wezley C Griffin
- From the Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7101
| | - Jun Gao
- From the Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7101
| | - Alicia K Byrd
- From the Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7101
| | - Shubeena Chib
- From the Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7101
| | - Kevin D Raney
- From the Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7101
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Abstract
Telomeres are specialized chromatin structures that protect chromosome ends from dangerous processing events. In most tissues, telomeres shorten with each round of cell division, placing a finite limit on cell growth. In rapidly dividing cells, including the majority of human cancers, cells bypass this growth limit through telomerase-catalyzed maintenance of telomere length. The dynamic properties of telomeres and telomerase render them difficult to study using ensemble biochemical and structural techniques. This review describes single-molecule approaches to studying how individual components of telomeres and telomerase contribute to function. Single-molecule methods provide a window into the complex nature of telomeres and telomerase by permitting researchers to directly visualize and manipulate the individual protein, DNA, and RNA molecules required for telomere function. The work reviewed in this article highlights how single-molecule techniques have been utilized to investigate the function of telomeres and telomerase.
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Affiliation(s)
- Joseph W Parks
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064; .,Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80303
| | - Michael D Stone
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064; .,Center for Molecular Biology of RNA, Santa Cruz, California 95064
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