1
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Xu L, Halma MTJ, Wuite GJL. Mapping fast DNA polymerase exchange during replication. Nat Commun 2024; 15:5328. [PMID: 38909023 PMCID: PMC11193749 DOI: 10.1038/s41467-024-49612-3] [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: 10/30/2023] [Accepted: 06/11/2024] [Indexed: 06/24/2024] Open
Abstract
Despite extensive studies on DNA replication, the exchange mechanisms of DNA polymerase during replication remain unclear. Existing models propose that this exchange is facilitated by protein partners like helicase. Here we present data, employing a combination of mechanical DNA manipulation and single fluorescent protein observation, that reveal DNA polymerase undergoing rapid and autonomous exchange during replication not coordinated by other proteins. The DNA polymerase shows fast unbinding and rebinding dynamics, displaying a preference for either exonuclease or polymerase activity, or pausing events, during each brief binding event. We also observed a 'memory effect' in DNA polymerase rebinding, i.e., the enzyme tends to preserve its prior activity upon reassociation. This effect, potentially linked to the ssDNA/dsDNA junction's conformation, might play a role in regulating binding preference enabling high processivity amidst rapid protein exchange. Taken together, our findings support an autonomous replication model that includes rapid protein exchange, burst of activity, and a 'memory effect' while moving processively forward.
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Affiliation(s)
- Longfu Xu
- Department of Physics and Astronomy and LaserLab, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands
| | - Matthew T J Halma
- Department of Physics and Astronomy and LaserLab, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands
| | - Gijs J L Wuite
- Department of Physics and Astronomy and LaserLab, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands.
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2
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Hoque ME, Kabir ML, Shiekh S, Balci H, Basu S. Stalling of Transcription by Putative G-quadruplex Sequences and CRISPR-dCas9. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.17.585391. [PMID: 38559215 PMCID: PMC10979993 DOI: 10.1101/2024.03.17.585391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Putative G-quadruplex forming sequences (PQS) have been identified in promoter sequences of prominent genes that are implicated among others in cancer and neurological disorders. We explored mechanistic aspects of CRISPR-dCas9-mediated gene expression regulation, which is transient and sequence specific unlike alternative approaches that lack such specificity or create permanent mutations, using the PQS in tyrosine hydroxylase (TH) and c-Myc promoters as model systems. We performed in vitro ensemble and single molecule investigations to study whether G-quadruplex (GQ) structures or dCas9 impede T7 RNA polymerase (RNAP) elongation process and whether orientation of these factors is significant. Our results demonstrate that dCas9 is more likely to block RNAP progression when the non-template strand is targeted. While the GQ in TH promoter was effectively destabilized when the dCas9 target site partially overlapped with the PQS, the c-Myc GQ remained folded and stalled RNAP elongation. We also determined that a minimum separation between the transcription start site and the dCas9 target site is required for effective stalling of RNAP by dCas9. Our study provides significant insights about the factors that impact dCas9-mediated transcription regulation when dCas9 targets the vicinity of sequences that form secondary structures and provides practical guidelines for designing guide RNA sequences.
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Affiliation(s)
- Mohammed Enamul Hoque
- Department of Chemistry and Biochemistry, Kent State University, Kent, OH 44242, USA
| | - Mohammad Lutful Kabir
- Department of Chemistry and Biochemistry, Kent State University, Kent, OH 44242, USA
| | - Sajad Shiekh
- Department of Physics, Kent State University, Kent, OH 44242, USA
| | - Hamza Balci
- Department of Physics, Kent State University, Kent, OH 44242, USA
| | - Soumitra Basu
- Department of Chemistry and Biochemistry, Kent State University, Kent, OH 44242, USA
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3
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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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4
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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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5
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Kodikara SG, Merkel KJ, Haas SJ, Shiekh S, Balci H. Detecting secondary structure formation with FRET-PAINT. Analyst 2023; 148:4655-4658. [PMID: 37671909 PMCID: PMC10561560 DOI: 10.1039/d3an01118f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/07/2023]
Abstract
We present single molecule studies demonstrating the capabilities of the FRET-PAINT method to detect secondary structures that would be challenging to detect with alternative methods, particularly single molecule FRET (smFRET). Instead of relying on the change in end-to-end separation as in smFRET, we use the change in accessibility to a small probe as the criterion for secondary structure formation and relative stability. As a model system, we study G-triplex formation by human telomeric repeat sequences in different structural contexts.
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Affiliation(s)
| | - Kylie J Merkel
- Department of Physics, Kent State University, Kent, OH, 44242, USA.
| | - Simon J Haas
- Department of Physics, Kent State University, Kent, OH, 44242, USA.
| | - 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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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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7
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Fang J, Xie C, Tao Y, Wei D. An overview of single-molecule techniques and applications in the study of nucleic acid structure and function. Biochimie 2023; 206:1-11. [PMID: 36179939 DOI: 10.1016/j.biochi.2022.09.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 09/20/2022] [Accepted: 09/22/2022] [Indexed: 11/02/2022]
Abstract
Nucleic acids are an indispensable component in all known life forms. The biological processes are regulated by Nucleic acids, which associate to form special high-order structures. since the high-level structures of nucleic acids are related to gene expression in cancer cells or viruses, it is very likely to become a potential drug target. Traditional biochemical methods are limited to distinguish the conformational distribution and dynamic transition process of single nucleic acid structure. The ligands based on the intermediate and transition states between different conformations are not designed by traditional biochemical methods. The single-molecule techniques enable real-time observation of the individual nucleic acid behavior due to its high resolution. Here, we introduce the application of single-molecule techniques in the study of small molecules to recognize nucleic acid structures, such as single-molecule FRET, magnetic tweezers, optical tweezers and atomic force microscopy. At the same time, we also introduce the specific advantages of single-molecule technology compared with traditional biochemical methods and some problems arisen in current research.
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Affiliation(s)
- Junkang Fang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China; Interdisciplinary Sciences Institute, Huazhong Agricultural University, Wuhan 430070, China; National Reference Laboratory of Veterinary Drug Residues (HZAU) and MAO Key Laboratory for Detection of Veterinary Drug Residues, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Shenzhen Institute of Nutrition and Health, Huazhong Agricultural University, Shenzhen 518000, China; Shenzhen Branch, Huazhong Agricultural University, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518000, China
| | - Congbao Xie
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China; Interdisciplinary Sciences Institute, Huazhong Agricultural University, Wuhan 430070, China; National Reference Laboratory of Veterinary Drug Residues (HZAU) and MAO Key Laboratory for Detection of Veterinary Drug Residues, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Shenzhen Institute of Nutrition and Health, Huazhong Agricultural University, Shenzhen 518000, China; Shenzhen Branch, Huazhong Agricultural University, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518000, China
| | - Yanfei Tao
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China; Interdisciplinary Sciences Institute, Huazhong Agricultural University, Wuhan 430070, China; National Reference Laboratory of Veterinary Drug Residues (HZAU) and MAO Key Laboratory for Detection of Veterinary Drug Residues, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Shenzhen Institute of Nutrition and Health, Huazhong Agricultural University, Shenzhen 518000, China; Shenzhen Branch, Huazhong Agricultural University, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518000, China.
| | - Dengguo Wei
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China; Interdisciplinary Sciences Institute, Huazhong Agricultural University, Wuhan 430070, China; National Reference Laboratory of Veterinary Drug Residues (HZAU) and MAO Key Laboratory for Detection of Veterinary Drug Residues, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Shenzhen Institute of Nutrition and Health, Huazhong Agricultural University, Shenzhen 518000, China; Shenzhen Branch, Huazhong Agricultural University, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518000, China.
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8
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Xu L, Halma MTJ, Wuite GJL. Unravelling How Single-Stranded DNA Binding Protein Coordinates DNA Metabolism Using Single-Molecule Approaches. Int J Mol Sci 2023; 24:ijms24032806. [PMID: 36769124 PMCID: PMC9917605 DOI: 10.3390/ijms24032806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Revised: 01/23/2023] [Accepted: 01/28/2023] [Indexed: 02/05/2023] Open
Abstract
Single-stranded DNA-binding proteins (SSBs) play vital roles in DNA metabolism. Proteins of the SSB family exclusively and transiently bind to ssDNA, preventing the DNA double helix from re-annealing and maintaining genome integrity. In the meantime, they interact and coordinate with various proteins vital for DNA replication, recombination, and repair. Although SSB is essential for DNA metabolism, proteins of the SSB family have been long described as accessory players, primarily due to their unclear dynamics and mechanistic interaction with DNA and its partners. Recently-developed single-molecule tools, together with biochemical ensemble techniques and structural methods, have enhanced our understanding of the different coordination roles that SSB plays during DNA metabolism. In this review, we discuss how single-molecule assays, such as optical tweezers, magnetic tweezers, Förster resonance energy transfer, and their combinations, have advanced our understanding of the binding dynamics of SSBs to ssDNA and their interaction with other proteins partners. We highlight the central coordination role that the SSB protein plays by directly modulating other proteins' activities, rather than as an accessory player. Many possible modes of SSB interaction with protein partners are discussed, which together provide a bigger picture of the interaction network shaped by SSB.
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9
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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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10
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Smeller L. Pressure Tuning Studies of Four-Stranded Nucleic Acid Structures. Int J Mol Sci 2023; 24:ijms24021803. [PMID: 36675317 PMCID: PMC9866529 DOI: 10.3390/ijms24021803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 01/10/2023] [Accepted: 01/12/2023] [Indexed: 01/18/2023] Open
Abstract
Four-stranded folded structures, such as G-quadruplexes and i-motifs in the genome, have attracted a growing interest nowadays since they have been discovered in the telomere and in several oncogene promoter regions. Their biological relevance is undeniable since their existence in living cells has been observed. In vivo they take part in the regulation of gene expression, in vitro they are used in the analytical biochemistry. They are attractive and promising targets for cancer therapy. Pressure studies can reveal specific aspects of the molecular processes. Pressure tuning experiments allow the determination of the volumetric parameters of the folded structures and of the folding-unfolding processes. Here, we review the thermodynamic parameters with a special focus on the volumetric ones, which were determined using pressure tuning spectroscopic experiments on the G-quadruplex and i-motif nucleic acid forms.
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Affiliation(s)
- László Smeller
- Department of Biophysics and Radiation Biology, Semmelweis University, Tűzoltó u. 37-47, 1094 Budapest, Hungary
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11
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Shiekh S, Jack A, Saurabh A, Mustafa G, Kodikara S, Gyawali P, Hoque M, Pressé S, Yildiz A, Balci H. Shelterin reduces the accessibility of telomeric overhangs. Nucleic Acids Res 2022; 50:12885-12895. [PMID: 36511858 PMCID: PMC9825182 DOI: 10.1093/nar/gkac1176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 10/25/2022] [Accepted: 11/25/2022] [Indexed: 12/15/2022] Open
Abstract
Telomeres terminate with a 50-300 bases long single-stranded G-rich overhang, which can be misrecognized as a DNA damage repair site. Shelterin plays critical roles in maintaining and protecting telomere ends by regulating access of various physiological agents to telomeric DNA, but the underlying mechanism is not well understood. Here, we measure how shelterin affects the accessibility of long telomeric overhangs by monitoring transient binding events of a short complementary peptide nucleic acid (PNA) probe using FRET-PAINT in vitro. We observed that the POT1 subunit of shelterin reduces the accessibility of the PNA probe by ∼2.5-fold, indicating that POT1 effectively binds to and protects otherwise exposed telomeric sequences. In comparison, a four-component shelterin stabilizes POT1 binding to the overhang by tethering POT1 to the double-stranded telomeric DNA and reduces the accessibility of telomeric overhangs by ∼5-fold. This enhanced protection suggests shelterin restructures the junction between single and double-stranded telomere, which is otherwise the most accessible part of the telomeric overhang.
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Affiliation(s)
- Sajad Shiekh
- Department of Physics, Kent State University, Kent, OH 44242, USA
| | - Amanda Jack
- Biophysics Graduate Group, University of California, Berkeley, CA 94720, USA
| | - Ayush Saurabh
- Center for Biological Physics, Department of Physics, Arizona State University, Tempe, AZ 85287, USA
| | - Golam Mustafa
- Department of Physics, Kent State University, Kent, OH 44242, USA
| | | | - Prabesh Gyawali
- Department of Physics, Kent State University, Kent, OH 44242, USA
| | - Mohammed Enamul Hoque
- Department of Chemistry and Biochemistry, Kent State University, Kent, OH 44242, USA
| | - Steve Pressé
- Center for Biological Physics, Department of Physics, Arizona State University, Tempe, AZ 85287, USA
- School of Molecular Science, Arizona State University, Tempe, AZ 85287, USA
| | - Ahmet Yildiz
- Biophysics Graduate Group, University of California, Berkeley, CA 94720, USA
- Physics Department, University of California, Berkeley, CA 94720, USA
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Hamza Balci
- Department of Physics, Kent State University, Kent, OH 44242, USA
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12
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Song QX, Lai CW, Liu NN, Hou XM, Xi XG. DEAD-box RNA helicase Dbp2 binds to G-quadruplex nucleic acids and regulates different conformation of G-quadruplex DNA. Biochem Biophys Res Commun 2022; 634:182-188. [DOI: 10.1016/j.bbrc.2022.10.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 10/01/2022] [Indexed: 11/25/2022]
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13
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Abstract
We present single-molecule experimental and computational modeling studies investigating the accessibility of human telomeric overhangs of physiologically relevant lengths. We studied 25 different overhangs that contain 4-28 repeats of GGGTTA (G-Tract) sequence and accommodate one to seven tandem G-quadruplex (GQ) structures. Using the FRET-PAINT method, we probed the distribution of accessible sites via a short imager strand, which is complementary to a G-Tract and transiently binds to available sites. We report accessibility patterns that periodically change with overhang length and interpret these patterns in terms of the underlying folding landscape and folding frustration. Overhangs that have [4n]G-Tracts, (12, 16, 20…) demonstrate the broadest accessibility patterns where the peptide nucleic acid probe accesses G-Tracts throughout the overhang. On the other hand, constructs with [4n+2]G-Tracts, (14, 18, 22…) have narrower patterns where the neighborhood of the junction between single- and double-stranded telomeres is most accessible. We interpret these results as the folding frustration being higher in [4n]G-Tract constructs compared to [4n+2]G-Tract constructs. We also developed a computational model that tests the consistency of different folding stabilities and cooperativities between neighboring GQs with the observed accessibility patterns. Our experimental and computational studies suggest the neighborhood of the junction between single- and double-stranded telomeres is least stable and most accessible, which is significant as this is a potential site where the connection between POT1/TPP1 (bound to single-stranded telomere) and other shelterin proteins (localized on double-stranded telomere) is established.
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14
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Dziuba D. Environmentally sensitive fluorescent nucleoside analogues as probes for nucleic acid - protein interactions: molecular design and biosensing applications. Methods Appl Fluoresc 2022; 10. [PMID: 35738250 DOI: 10.1088/2050-6120/ac7bd8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 06/23/2022] [Indexed: 11/12/2022]
Abstract
Fluorescent nucleoside analogues (FNAs) are indispensable in studying the interactions of nucleic acids with nucleic acid-binding proteins. By replacing one of the poorly emissive natural nucleosides, FNAs enable real-time optical monitoring of the binding interactions in solutions, under physiologically relevant conditions, with high sensitivity. Besides that, FNAs are widely used to probe conformational dynamics of biomolecular complexes using time-resolved fluorescence methods. Because of that, FNAs are tools of high utility for fundamental biological research, with potential applications in molecular diagnostics and drug discovery. Here I review the structural and physical factors that can be used for the conversion of the molecular binding events into a detectable fluorescence output. Typical environmentally sensitive FNAs, their properties and applications, and future challenges in the field are discussed.
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Affiliation(s)
- Dmytro Dziuba
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Université de Strasbourg, 74 Route du Rhin, Illkirch-Graffenstaden, Grand Est, 67401, FRANCE
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15
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Monsen RC, DeLeeuw LW, Dean W, Gray R, Chakravarthy S, Hopkins J, Chaires J, Trent J. Long promoter sequences form higher-order G-quadruplexes: an integrative structural biology study of c-Myc, k-Ras and c-Kit promoter sequences. Nucleic Acids Res 2022; 50:4127-4147. [PMID: 35325198 PMCID: PMC9023277 DOI: 10.1093/nar/gkac182] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 03/03/2022] [Accepted: 03/21/2022] [Indexed: 12/15/2022] Open
Abstract
We report on higher-order G-quadruplex structures adopted by long promoter sequences obtained by an iterative integrated structural biology approach. Our approach uses quantitative biophysical tools (analytical ultracentrifugation, small-angle X-ray scattering, and circular dichroism spectroscopy) combined with modeling and molecular dynamics simulations, to derive self-consistent structural models. The formal resolution of our approach is 18 angstroms, but in some cases structural features of only a few nucleotides can be discerned. We report here five structures of long (34-70 nt) wild-type sequences selected from three cancer-related promoters: c-Myc, c-Kit and k-Ras. Each sequence studied has a unique structure. Three sequences form structures with two contiguous, stacked, G-quadruplex units. One longer sequence from c-Myc forms a structure with three contiguous stacked quadruplexes. A longer c-Kit sequence forms a quadruplex-hairpin structure. Each structure exhibits interfacial regions between stacked quadruplexes or novel loop geometries that are possible druggable targets. We also report methodological advances in our integrated structural biology approach, which now includes quantitative CD for counting stacked G-tetrads, DNaseI cleavage for hairpin detection and SAXS model refinement. Our results suggest that higher-order quadruplex assemblies may be a common feature within the genome, rather than simple single quadruplex structures.
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Affiliation(s)
- Robert C Monsen
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - Lynn W DeLeeuw
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - William L Dean
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - Robert D Gray
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - Srinivas Chakravarthy
- The Biophysics Collaborative Access Team (BioCAT), Department of Biological, Chemical, and Physical Sciences, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Jesse B Hopkins
- The Biophysics Collaborative Access Team (BioCAT), Department of Biological, Chemical, and Physical Sciences, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Jonathan B Chaires
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
- Department of Medicine, University of Louisville, Louisville, KY 40202, USA
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY 40202, USA
| | - John O Trent
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
- Department of Medicine, University of Louisville, Louisville, KY 40202, USA
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY 40202, USA
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16
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Detecting G4 unwinding. Methods Enzymol 2022; 672:261-281. [DOI: 10.1016/bs.mie.2022.03.034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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17
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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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18
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Characterization of G-Quadruplexes Folding/Unfolding Dynamics and Interactions with Proteins from Single-Molecule Force Spectroscopy. Biomolecules 2021; 11:biom11111579. [PMID: 34827577 PMCID: PMC8615981 DOI: 10.3390/biom11111579] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 10/16/2021] [Accepted: 10/19/2021] [Indexed: 12/19/2022] Open
Abstract
G-quadruplexes (G4s) are stable secondary nucleic acid structures that play crucial roles in many fundamental biological processes. The folding/unfolding dynamics of G4 structures are associated with the replication and transcription regulation functions of G4s. However, many DNA G4 sequences can adopt a variety of topologies and have complex folding/unfolding dynamics. Determining the dynamics of G4s and their regulation by proteins remains challenging due to the coexistence of multiple structures in a heterogeneous sample. Here, in this mini-review, we introduce the application of single-molecule force-spectroscopy methods, such as magnetic tweezers, optical tweezers, and atomic force microscopy, to characterize the polymorphism and folding/unfolding dynamics of G4s. We also briefly introduce recent studies using single-molecule force spectroscopy to study the molecular mechanisms of G4-interacting proteins.
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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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Zhang C, Jing X, Guo L, Cui C, Hou X, Zuo T, Liu J, Shi J, Liu X, Zuo X, Li J, Chang C, Fan C, Wang L. Remote Photothermal Control of DNA Origami Assembly in Cellular Environments. NANO LETTERS 2021; 21:5834-5841. [PMID: 34133183 DOI: 10.1021/acs.nanolett.1c01821] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
In situ synthesis of DNA origami structures in living systems is highly desirable due to its potential in biological applications, which nevertheless is hampered by the requirement of thermal activation procedures. Here, we report a photothermal DNA origami assembly method in near-physiological environments. We find that the use of copper sulfide nanoparticles (CuS NPs) can mediate efficient near-infrared (NIR) photothermal conversion to remotely control the solution temperature. Under a 4 min NIR illumination and subsequent natural cooling, rapid and high-yield (>80%) assembly of various types of DNA origami nanostructures is achieved as revealed by atomic force microscopy and single-molecule fluorescence resonance energy transfer analysis. We further demonstrate the in situ assembly of DNA origami with high location precision in cell lysates and in cell culture environments.
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Affiliation(s)
- Chao Zhang
- Institute of Molecular Medicine, Shanghai Key Laboratory for Nucleic Acids Chemistry and Nanomedicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules and National Center for Translational Medicine, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Xinxin Jing
- Institute of Molecular Medicine, Shanghai Key Laboratory for Nucleic Acids Chemistry and Nanomedicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules and National Center for Translational Medicine, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Linjie Guo
- The Interdisciplinary Research Center, Shanghai Synchrotron Radiation Facility, Zhangjiang Laboratory, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, China
- Division of Physical Biology, CAS Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 201800, China
| | - Chengjun Cui
- The Interdisciplinary Research Center, Shanghai Synchrotron Radiation Facility, Zhangjiang Laboratory, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, China
| | - Xiaoling Hou
- Division of Physical Biology, CAS Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 201800, China
| | - Tingting Zuo
- Division of Physical Biology, CAS Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 201800, China
| | - Jiangbo Liu
- Institute of Molecular Medicine, Shanghai Key Laboratory for Nucleic Acids Chemistry and Nanomedicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China
| | - Jiye Shi
- Division of Physical Biology, CAS Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 201800, China
| | - Xiaoguo Liu
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules and National Center for Translational Medicine, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Xiaolei Zuo
- Institute of Molecular Medicine, Shanghai Key Laboratory for Nucleic Acids Chemistry and Nanomedicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China
| | - Jiang Li
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules and National Center for Translational Medicine, Shanghai Jiao Tong University, 200240, Shanghai, China
- The Interdisciplinary Research Center, Shanghai Synchrotron Radiation Facility, Zhangjiang Laboratory, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, China
- Division of Physical Biology, CAS Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 201800, China
| | - Chao Chang
- Key Laboratory of Physical Electronics and Devices of the Ministry of Education, Xi'an Jiaotong University, Xi'an, Shanxi 710049, China
| | - Chunhai Fan
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules and National Center for Translational Medicine, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Lihua Wang
- The Interdisciplinary Research Center, Shanghai Synchrotron Radiation Facility, Zhangjiang Laboratory, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, China
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, 500 Dongchuan Road, Shanghai, 200127, China
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21
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Mustafa G, Shiekh S, Gc K, Abeysirigunawardena S, Balci H. Interrogating accessibility of telomeric sequences with FRET-PAINT: evidence for length-dependent telomere compaction. Nucleic Acids Res 2021; 49:3371-3380. [PMID: 33693934 PMCID: PMC8034622 DOI: 10.1093/nar/gkab067] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 01/23/2021] [Accepted: 03/08/2021] [Indexed: 12/25/2022] Open
Abstract
Single-stranded telomeric overhangs are ∼200 nucleotides long and can form tandem G-quadruplex (GQ) structures, which reduce their accessibility to nucleases and proteins that activate DNA damage response. Whether these tandem GQs further stack to form compact superstructures, which may provide better protection for longer telomeres, is not known. We report single-molecule measurements where the accessibility of 24-144 nucleotide long human telomeric DNA molecules is interrogated by a short PNA molecule that is complementary to a single GGGTTA repeat, as implemented in the FRET-PAINT method. Binding of the PNA strand to available GGGTTA sequences results in discrete FRET bursts which were analyzed in terms of their dwell times, binding frequencies, and topographic distributions. The binding frequencies were greater for binding to intermediate regions of telomeric DNA compared to 3'- or 5'-ends, suggesting these regions are more accessible. Significantly, the binding frequency per telomeric repeat monotonically decreased with increasing telomere length. These results are consistent with telomeres forming more compact structures at longer lengths, reducing accessibility of these critical genomic sites.
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Affiliation(s)
- Golam Mustafa
- Department of Physics, Kent State University, Kent, OH 44242, USA
| | - Sajad Shiekh
- Department of Physics, Kent State University, Kent, OH 44242, USA
| | - Keshav Gc
- Department of Chemistry and Biochemistry, Kent State University, Kent, OH 44242, USA
| | | | - Hamza Balci
- Department of Physics, Kent State University, Kent, OH 44242, USA
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22
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Lu Y, Bianco P. High-yield purification of exceptional-quality, single-molecule DNA substrates. J Biol Methods 2021; 8:e145. [PMID: 33889652 PMCID: PMC8054919 DOI: 10.14440/jbm.2021.350] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 12/10/2020] [Accepted: 01/02/2021] [Indexed: 12/13/2022] Open
Abstract
Single-molecule studies involving DNA or RNA, require homogeneous preparations of nucleic acid substrates of exceptional quality. Over the past several years, a variety of methods have been published describing different purification methods but these are frustratingly inconsistent with variable yields even in the hands of experienced bench scientists. To address these issues, we present an optimized and straightforward, column-based approach that is reproducible and produces high yields of substrates or substrate components of exceptional quality. Central to the success of the method presented is the use of a non-porous anion exchange resin. In addition to the use of this resin, we encourage the optimization of each step in the construction of substrates. The fully optimized method produces high yields of a hairpin DNA substrate of exceptional quality. While this substrate is suitable for single-molecule, magnetic tweezer experiments, the described method is readily adaptable to the production of DNA substrates for the majority of single-molecule studies involving nucleic acids ranging in size from 70–15000 bp.
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Affiliation(s)
- Yue Lu
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE 68198-6025, USA
| | - Piero Bianco
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE 68198-6025, USA
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23
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NDI-induced Topological Conversion of Human Telomeric G-Quadruplexes from Hybrid-2 to Parallel Form. Chem Res Chin Univ 2021. [DOI: 10.1007/s40242-021-1022-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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24
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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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25
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Hao X, Wang C, Wang Y, Li C, Hou J, Zhang F, Kang C, Gao L. Topological conversion of human telomeric G-quadruplexes from hybrid to parallel form induced by naphthalene diimide ligands. Int J Biol Macromol 2020; 167:1048-1058. [PMID: 33188810 DOI: 10.1016/j.ijbiomac.2020.11.059] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 11/09/2020] [Accepted: 11/09/2020] [Indexed: 12/17/2022]
Abstract
G-quadruplexes (GQs) have become promising anti-cancer therapeutic targets, which are formed by the folding of a guanine-rich repeat DNA/RNA sequence at human telomeres or oncogene promoters. Polymorphism has been observed for the folding topologies of intramolecular GQs. Here we report the topological conversion of human telomeric GQ induced by naphthalene diimide (NDI) ligands in K+ solution. The ligands selectively induce metastable hybrid-type GQs to highly stable parallel-type GQ at physiological temperature (37 °C) in dilute aqueous solutions and under crowding conditions that mimic cellular bioenvironment. According to spectroscopic analyses, the topological conversion is speculated to undergo stepwise unfolding of hybrid-type GQ through intermediate states to parallel-type GQ. The results will prompt further studies on the designs of ligands with GQ conformation regulation functions and nanotechnological systems based on nucleic acids with dynamic regulation of GQ conformation.
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Affiliation(s)
- Xueyu Hao
- Laboratory of Polymer Composite and Engineering, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China; University of Science and Technology of China, Hefei 230026, China
| | - Chunyu Wang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China
| | - Yu Wang
- Laboratory of Polymer Composite and Engineering, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China; University of Science and Technology of China, Hefei 230026, China
| | - Chunjie Li
- Laboratory of Polymer Composite and Engineering, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Jingwei Hou
- Laboratory of Polymer Composite and Engineering, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Feng Zhang
- Laboratory of Polymer Composite and Engineering, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Chuanqing Kang
- Laboratory of Polymer Composite and Engineering, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China; University of Science and Technology of China, Hefei 230026, China.
| | - Lianxun Gao
- Laboratory of Polymer Composite and Engineering, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
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26
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Maleki P, Mustafa G, Gyawali P, Budhathoki JB, Ma Y, Nagasawa K, Balci H. Quantifying the impact of small molecule ligands on G-quadruplex stability against Bloom helicase. Nucleic Acids Res 2020; 47:10744-10753. [PMID: 31544934 PMCID: PMC6847008 DOI: 10.1093/nar/gkz803] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Revised: 08/28/2019] [Accepted: 09/09/2019] [Indexed: 01/28/2023] Open
Abstract
G-quadruplex (GQ) stabilizing small molecule (SM) ligands have been used to stabilize human telomeric GQ (hGQ) to inhibit telomerase activity, or non-telomeric GQs to manipulate gene expression at transcription or translation level. GQs are known to inhibit DNA replication unless destabilized by helicases, such as Bloom helicase (BLM). Even though the impact of SM ligands on thermal stability of GQs is commonly used to characterize their efficacy, how these ligands influence helicase-mediated GQ unfolding is not well understood. Three prominent SM ligands (an oxazole telomestatin derivative, pyridostatin, and PhenDC3), which thermally stabilize hGQ at different levels, were utilized in this study. How these ligands influence BLM-mediated hGQ unfolding was investigated using two independent single-molecule approaches. While the frequency of dynamic hGQ unfolding events was used as the metric in the first approach, the second approach was based on quantifying the cumulative unfolding activity as a function of time. All three SM ligands inhibited BLM activity at similar levels, 2–3 fold, in both approaches. Our observations suggest that the impact of SM ligands on GQ thermal stability is not an ideal predictor for their inhibition of helicase-mediated unfolding, which is physiologically more relevant.
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Affiliation(s)
- Parastoo Maleki
- Department of Physics, Kent State University, Kent, OH 44242, USA
| | - Golam Mustafa
- Department of Physics, Kent State University, Kent, OH 44242, USA
| | - Prabesh Gyawali
- Department of Physics, Kent State University, Kent, OH 44242, USA
| | | | - Yue Ma
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Kazuo Nagasawa
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Hamza Balci
- Department of Physics, Kent State University, Kent, OH 44242, USA
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27
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Hagen T, Malinowska AL, Lightfoot HL, Bigatti M, Hall J. Site-Specific Fluorophore Labeling of Guanosines in RNA G-Quadruplexes. ACS OMEGA 2019; 4:8472-8479. [PMID: 31459936 PMCID: PMC6648711 DOI: 10.1021/acsomega.9b00704] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 04/24/2019] [Indexed: 05/08/2023]
Abstract
RNA G-quadruplexes are RNA secondary structures that are implicated in many cellular processes. Although conventional biophysical techniques are widely used for their in vitro characterization, more advanced methods are needed to study complex equilibria and the kinetics of their folding. We have developed a new Förster resonance energy-transfer-based method to detect the folding of RNA G-quadruplexes, which is enabled by labeling the 2'-positions of participating guanosines with fluorophores. Importantly, this does not interfere with the required anti conformation of the nucleobase in a quadruplex with parallel topology. Sequential click reactions on the solid phase and in solution using a stop-and-go strategy circumvented the issue of unselective cross-labeling. We exemplified the method on a series of sequences under different assay conditions. In contrast to the commonly used end-labeling approach, our internal labeling strategy would also allow the study of G-quadruplex formation in long functional RNAs.
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28
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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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Ihmels H, Jiang S, Mahmoud MMA, Schönherr H, Wesner D, Zamrik I. Fluorimetric Detection of G-Quadruplex DNA in Solution and Adsorbed on Surfaces with a Selective Trinuclear Cyanine Dye. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:11866-11877. [PMID: 30173518 DOI: 10.1021/acs.langmuir.8b02382] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Quadruplex DNA, which is a relevant target for anticancer therapies, may alter its conformation because of interactions with interfaces. In pursuit of a versatile methodology to probe adsorption-induced conformational changes, the interaction between a fluorescent [2.2.2]heptamethinecyanine dye and quadruplex DNA (G4-DNA) was studied in solution and on surfaces. In solution, the cyanine dye exhibits a strong light-up effect upon the association with G4-DNA without interference from double-stranded DNA. In addition, a terminal π-stacking as a binding mode between the cyanine dye and G4-DNA is concluded using NMR spectroscopy. To unravel the effects of adsorption on the conformation of quadruplex-DNA, G4-DNA, and double-stranded and single-stranded DNA were adsorbed to positively charged poly(allylamine) hydrochloride (PAH) surfaces, both in planar and in constrained 55 nm diameter aluminum oxide nanopore formats. All DNA forms showed a very strong affinity to the PAH surfaces as shown by surface plasmon resonance and reflectometric interference spectroscopy. The significant increase of the fluorescence emission intensity of the cyanine light-up probe observed exclusively for surface immobilized G4-DNA affords evidence for the adsorption of G4-DNA on PAH with retained quadruplex conformation.
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Affiliation(s)
- Heiko Ihmels
- Department of Chemistry and Biology , University of Siegen, and Center of Micro- and Nanochemistry and Engineering (Cμ) , Adolf-Reichwein-Str. 2 , 57068 Siegen , Germany
| | - Siyu Jiang
- Department of Chemistry and Biology , University of Siegen, and Center of Micro- and Nanochemistry and Engineering (Cμ) , Adolf-Reichwein-Str. 2 , 57068 Siegen , Germany
| | - Mohamed M A Mahmoud
- Department of Chemistry and Biology , University of Siegen, and Center of Micro- and Nanochemistry and Engineering (Cμ) , Adolf-Reichwein-Str. 2 , 57068 Siegen , Germany
| | - Holger Schönherr
- Department of Chemistry and Biology , University of Siegen, and Center of Micro- and Nanochemistry and Engineering (Cμ) , Adolf-Reichwein-Str. 2 , 57068 Siegen , Germany
| | - Daniel Wesner
- Department of Chemistry and Biology , University of Siegen, and Center of Micro- and Nanochemistry and Engineering (Cμ) , Adolf-Reichwein-Str. 2 , 57068 Siegen , Germany
| | - Imad Zamrik
- Department of Chemistry and Biology , University of Siegen, and Center of Micro- and Nanochemistry and Engineering (Cμ) , Adolf-Reichwein-Str. 2 , 57068 Siegen , Germany
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Mustafa G, Chuang CY, Roy WA, Farhath MM, Pokhrel N, Ma Y, Nagasawa K, Antony E, Comstock MJ, Basu S, Balci H. A force sensor that converts fluorescence signal into force measurement utilizing short looped DNA. Biosens Bioelectron 2018; 121:34-40. [PMID: 30195120 DOI: 10.1016/j.bios.2018.08.073] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 08/13/2018] [Accepted: 08/30/2018] [Indexed: 01/27/2023]
Abstract
A force sensor concept is presented where fluorescence signal is converted into force information via single-molecule Förster resonance energy transfer (smFRET). The basic design of the sensor is a ~100 base pair (bp) long double stranded DNA (dsDNA) that is restricted to a looped conformation by a nucleic acid secondary structure (NAS) that bridges its ends. The looped dsDNA generates a tension across the NAS and unfolds it when the tension is high enough. The FRET efficiency between donor and acceptor (D&A) fluorophores placed across the NAS reports on its folding state. Three dsDNA constructs with different lengths were bridged by a DNA hairpin and KCl was titrated to change the applied force. After these proof-of-principle measurements, one of the dsDNA constructs was used to maintain the G-quadruplex (GQ) construct formed by thrombin binding aptamer (TBA) under tension while it interacted with a destabilizing protein and stabilizing small molecule. The force required to unfold TBA-GQ was independently investigated with high-resolution optical tweezers (OT) measurements that established the relevant force to be a few pN, which is consistent with the force generated by the looped dsDNA. The proposed method is particularly promising as it enables studying NAS, protein, and small molecule interactions using a highly-parallel FRET-based assay while the NAS is kept under an approximately constant force.
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Affiliation(s)
- Golam Mustafa
- Department of Physics, Kent State University, Kent, OH 44242, United States
| | - Cho-Ying Chuang
- Department of Physics, Michigan State University, East Lansing, MI 48824, United States
| | - William A Roy
- Department of Physics, Kent State University, Kent, OH 44242, United States
| | - Mohamed M Farhath
- Department of Chemistry and Biochemistry, Kent State University, Kent, OH 44242, United States
| | - Nilisha Pokhrel
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53201, United States
| | - Yue Ma
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Kazuo Nagasawa
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Edwin Antony
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53201, United States
| | - Matthew J Comstock
- Department of Physics, Michigan State University, East Lansing, MI 48824, United States
| | - Soumitra Basu
- Department of Chemistry and Biochemistry, Kent State University, Kent, OH 44242, United States
| | - Hamza Balci
- Department of Physics, Kent State University, Kent, OH 44242, United States.
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Bhattacharjee A, Wang Y, Diao J, Price CM. Dynamic DNA binding, junction recognition and G4 melting activity underlie the telomeric and genome-wide roles of human CST. Nucleic Acids Res 2017; 45:12311-12324. [PMID: 29040642 PMCID: PMC5716219 DOI: 10.1093/nar/gkx878] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 09/22/2017] [Indexed: 11/14/2022] Open
Abstract
Human CST (CTC1-STN1-TEN1) is a ssDNA-binding complex that helps resolve replication problems both at telomeres and genome-wide. CST resembles Replication Protein A (RPA) in that the two complexes harbor comparable arrays of OB-folds and have structurally similar small subunits. However, the overall architecture and functions of CST and RPA are distinct. Currently, the mechanism underlying CST action at diverse replication issues remains unclear. To clarify CST mechanism, we examined the capacity of CST to bind and resolve DNA structures found at sites of CST activity. We show that CST binds preferentially to ss-dsDNA junctions, an activity that can explain the incremental nature of telomeric C-strand synthesis following telomerase action. We also show that CST unfolds G-quadruplex structures, thus providing a mechanism for CST to facilitate replication through telomeres and other GC-rich regions. Finally, smFRET analysis indicates that CST binding to ssDNA is dynamic with CST complexes undergoing concentration-dependent self-displacement. These findings support an RPA-based model where dissociation and re-association of individual OB-folds allow CST to mediate loading and unloading of partner proteins to facilitate various aspects of telomere replication and genome-wide resolution of replication stress.
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Affiliation(s)
| | - Yongyao Wang
- Department of Cancer Biology, University of Cincinnati, Cincinnati, OH 45267, USA.,School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - Jiajie Diao
- Department of Cancer Biology, University of Cincinnati, Cincinnati, OH 45267, USA
| | - Carolyn M Price
- Department of Cancer Biology, University of Cincinnati, Cincinnati, OH 45267, USA
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