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Ooga M, Sahayasheela VJ, Hirose Y, Sasaki D, Hashiya K, Bando T, Sugiyama H. A dual DNA-binding conjugate that selectively recognizes G-quadruplex structures. Chem Commun (Camb) 2024. [PMID: 39072583 DOI: 10.1039/d4cc01572j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
G-quadruplex (G4) structures play roles in various biological processes, but the challenge lies in specific targeting. To address this, we synthesized a conjugate capable of recognizing the G4 structure and its proximal duplex. Our conjugate can enable recognition of specific G4s in the human genome to understand and target those structures.
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Affiliation(s)
- Mitsuharu Ooga
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan.
| | - Vinodh J Sahayasheela
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan.
| | - Yuki Hirose
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan.
| | - Daisuke Sasaki
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan.
| | - Kaori Hashiya
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan.
| | - Toshikazu Bando
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan.
| | - Hiroshi Sugiyama
- Institute for Integrated Cell-Material Sciences (iCeMS), Kyoto University, Yoshida-ushinomiyacho, Sakyo-ku, Kyoto 606-8501, Japan.
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2
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Michael Sabo T, Trent JO, Chaires JB, Monsen RC. Strategy for modeling higher-order G-quadruplex structures recalcitrant to NMR determination. Methods 2024; 230:9-20. [PMID: 39032720 DOI: 10.1016/j.ymeth.2024.07.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Revised: 06/22/2024] [Accepted: 07/17/2024] [Indexed: 07/23/2024] Open
Abstract
Guanine-rich nucleic acids can form intramolecularly folded four-stranded structures known as G-quadruplexes (G4s). Traditionally, G4 research has focused on short, highly modified DNA or RNA sequences that form well-defined homogeneous compact structures. However, the existence of longer sequences with multiple G4 repeats, from proto-oncogene promoters to telomeres, suggests the potential for more complex higher-order structures with multiple G4 units that might offer selective drug-targeting sites for therapeutic development. These larger structures present significant challenges for structural characterization by traditional high-resolution methods like multi-dimensional NMR and X-ray crystallography due to their molecular complexity. To address this current challenge, we have developed an integrated structural biology (ISB) platform, combining experimental and computational methods to determine self-consistent molecular models of higher-order G4s (xG4s). Here we outline our ISB method using two recent examples from our lab, an extended c-Myc promoter and long human telomere G4 repeats, that highlights the utility and generality of our approach to characterizing biologically relevant xG4s.
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Affiliation(s)
- T Michael Sabo
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY, United States
| | - John O Trent
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY, United States
| | - Jonathan B Chaires
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY, United States
| | - Robert C Monsen
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY, United States.
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Vianney YM, Dierks D, Weisz K. Structural Differences at Quadruplex-Duplex Interfaces Enable Ligand-Induced Topological Transitions. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2309891. [PMID: 38477454 PMCID: PMC11200018 DOI: 10.1002/advs.202309891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2023] [Revised: 02/13/2024] [Indexed: 03/14/2024]
Abstract
Quadruplex-duplex (QD) junctions, which represent unique structural motifs of both biological and technological significance, have been shown to constitute high-affinity binding sites for various ligands. A QD hybrid construct based on a human telomeric sequence, which harbors a duplex stem-loop in place of a short lateral loop, is structurally characterized by NMR. It folds into two major species with a (3+1) hybrid and a chair-type (2+2) antiparallel quadruplex domain coexisting in a K+ buffer solution. The antiparallel species is stabilized by an unusual capping structure involving a thymine and protonated adenine base AH+ of the lateral loop facing the hairpin duplex to form a T·AH+·G·C quartet with the interfacial G·C base pair at neutral pH. Addition and binding of Phen-DC3 to the QD hybrid mixture by its partial intercalation at corresponding QD junctions leads to a topological transition with exclusive formation of the (3+1) hybrid fold. In agreement with the available experimental data, such an unprecedented discrimination of QD junctions by a ligand can be rationalized following an induced fit mechanism.
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Affiliation(s)
- Yoanes Maria Vianney
- Institut für BiochemieUniversität GreifswaldFelix‐Hausdorff‐Str. 4D‐17489GreifswaldGermany
| | - Dorothea Dierks
- Institut für BiochemieUniversität GreifswaldFelix‐Hausdorff‐Str. 4D‐17489GreifswaldGermany
| | - Klaus Weisz
- Institut für BiochemieUniversität GreifswaldFelix‐Hausdorff‐Str. 4D‐17489GreifswaldGermany
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Fleming AM, Guerra Castañaza Jenkins BL, Buck BA, Burrows CJ. DNA Damage Accelerates G-Quadruplex Folding in a Duplex-G-Quadruplex-Duplex Context. J Am Chem Soc 2024; 146. [PMID: 38602473 PMCID: PMC11046481 DOI: 10.1021/jacs.4c00960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2024] [Revised: 03/27/2024] [Accepted: 03/28/2024] [Indexed: 04/12/2024]
Abstract
Molecular details for the impact of DNA damage on folding of potential G-quadruplex sequences (PQSs) to noncanonical DNA structures involved in gene regulation are poorly understood. Here, the effects of DNA base damage and strand breaks on PQS folding kinetics were studied in the context of the VEGF promoter sequence embedded between two DNA duplex anchors, termed a duplex-G-quadruplex-duplex (DGD) motif. This DGD scaffold imposes constraints on the PQS folding process that more closely mimic those found in genomic DNA. Folding kinetics were monitored by circular dichroism (CD) to find folding half-lives ranging from 2 s to 12 min depending on the DNA damage type and sequence position. The presence of Mg2+ ions and G-quadruplex (G4)-binding protein APE1 facilitated the folding reactions. A strand break placing all four G runs required for G4 formation on one side of the break accelerated the folding rate by >150-fold compared to the undamaged sequence. Combined 1D 1H NMR and CD analyses confirmed that isothermal folding of the VEGF-DGD constructs yielded spectral signatures that suggest the formation of G4 motifs and demonstrated a folding dependency on the nature and location of DNA damage. Importantly, the PQS folding half-lives measured are relevant to replication, transcription, and DNA repair time frames.
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Affiliation(s)
- Aaron M. Fleming
- Department of Chemistry, University
of Utah, 315 South 1400 East, Salt
Lake City, Utah 84112-0850, United States
| | | | - Bethany A. Buck
- Department of Chemistry, University
of Utah, 315 South 1400 East, Salt
Lake City, Utah 84112-0850, United States
| | - Cynthia J. Burrows
- Department of Chemistry, University
of Utah, 315 South 1400 East, Salt
Lake City, Utah 84112-0850, United States
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Fleming AM, Jenkins BLGC, Buck BA, Burrows CJ. DNA Damage Accelerates G-Quadruplex Folding in a Duplex-G-Quadruplex-Duplex Context. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.20.576387. [PMID: 38293204 PMCID: PMC10827223 DOI: 10.1101/2024.01.20.576387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Molecular details for DNA damage impact on the folding of potential G-quadruplex sequences (PQS) to non-canonical DNA structures that are involved in gene regulation are poorly understood. Here, the effects of DNA base damage and strand breaks on PQS folding kinetics were studied in the context of the VEGF promoter sequence embedded between two DNA duplex anchors, referred to as a duplex-G-quadruplex-duplex (DGD) motif. This DGD scaffold imposes constraints on the PQS folding process that more closely mimic those found in genomic DNA. Folding kinetics were monitored by circular dichroism (CD) to find folding half-lives ranging from 2 s to 12 min depending on the DNA damage type and sequence position. The presence of Mg2+ ions and the G-quadruplex (G4)-binding protein APE1 facilitated the folding reactions. A strand break placing all four G runs required for G4 formation on one side of the break accelerated the folding rate by >150-fold compared to the undamaged sequence. Combined 1D 1H-NMR and CD analyses confirmed that isothermal folding of the VEGF-DGD constructs yielded spectral signatures that suggest formation of G4 motifs, and demonstrated a folding dependency with the nature and location of DNA damage. Importantly, the PQS folding half-lives measured are relevant to replication, transcription, and DNA repair time frames.
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Affiliation(s)
- Aaron M Fleming
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, UT 84112-0850 United States
| | | | - Bethany A Buck
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, UT 84112-0850 United States
| | - Cynthia J Burrows
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, UT 84112-0850 United States
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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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Sato K, Knipscheer P. G-quadruplex resolution: From molecular mechanisms to physiological relevance. DNA Repair (Amst) 2023; 130:103552. [PMID: 37572578 DOI: 10.1016/j.dnarep.2023.103552] [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: 05/24/2023] [Revised: 07/29/2023] [Accepted: 08/01/2023] [Indexed: 08/14/2023]
Abstract
Guanine-rich DNA sequences can fold into stable four-stranded structures called G-quadruplexes or G4s. Research in the past decade demonstrated that G4 structures are widespread in the genome and prevalent in regulatory regions of actively transcribed genes. The formation of G4s has been tightly linked to important biological processes including regulation of gene expression and genome maintenance. However, they can also pose a serious threat to genome integrity especially by impeding DNA replication, and G4-associated somatic mutations have been found accumulated in the cancer genomes. Specialised DNA helicases and single stranded DNA binding proteins that can resolve G4 structures play a crucial role in preventing genome instability. The large variety of G4 unfolding proteins suggest the presence of multiple G4 resolution mechanisms in cells. Recently, there has been considerable progress in our detailed understanding of how G4s are resolved, especially during DNA replication. In this review, we first discuss the current knowledge of the genomic G4 landscapes and the impact of G4 structures on DNA replication and genome integrity. We then describe the recent progress on the mechanisms that resolve G4 structures and their physiological relevance. Finally, we discuss therapeutic opportunities to target G4 structures.
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Affiliation(s)
- Koichi Sato
- Oncode Institute, Hubrecht Institute-KNAW & University Medical Center Utrecht, Utrecht, the Netherlands.
| | - Puck Knipscheer
- Oncode Institute, Hubrecht Institute-KNAW & University Medical Center Utrecht, Utrecht, the Netherlands; Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands.
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Biela A, Hammermeister A, Kaczmarczyk I, Walczak M, Koziej L, Lin TY, Glatt S. The diverse structural modes of tRNA binding and recognition. J Biol Chem 2023; 299:104966. [PMID: 37380076 PMCID: PMC10424219 DOI: 10.1016/j.jbc.2023.104966] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 06/20/2023] [Accepted: 06/22/2023] [Indexed: 06/30/2023] Open
Abstract
tRNAs are short noncoding RNAs responsible for decoding mRNA codon triplets, delivering correct amino acids to the ribosome, and mediating polypeptide chain formation. Due to their key roles during translation, tRNAs have a highly conserved shape and large sets of tRNAs are present in all living organisms. Regardless of sequence variability, all tRNAs fold into a relatively rigid three-dimensional L-shaped structure. The conserved tertiary organization of canonical tRNA arises through the formation of two orthogonal helices, consisting of the acceptor and anticodon domains. Both elements fold independently to stabilize the overall structure of tRNAs through intramolecular interactions between the D- and T-arm. During tRNA maturation, different modifying enzymes posttranscriptionally attach chemical groups to specific nucleotides, which not only affect translation elongation rates but also restrict local folding processes and confer local flexibility when required. The characteristic structural features of tRNAs are also employed by various maturation factors and modification enzymes to assure the selection, recognition, and positioning of specific sites within the substrate tRNAs. The cellular functional repertoire of tRNAs continues to extend well beyond their role in translation, partly, due to the expanding pool of tRNA-derived fragments. Here, we aim to summarize the most recent developments in the field to understand how three-dimensional structure affects the canonical and noncanonical functions of tRNA.
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Affiliation(s)
- Anna Biela
- Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland
| | | | - Igor Kaczmarczyk
- Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland; Doctoral School of Exact and Natural Sciences, Jagiellonian University, Krakow, Poland
| | - Marta Walczak
- Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland; Doctoral School of Exact and Natural Sciences, Jagiellonian University, Krakow, Poland
| | - Lukasz Koziej
- Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland
| | - Ting-Yu Lin
- Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland.
| | - Sebastian Glatt
- Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland.
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Lyu K, Kwok CK. RNA G-quadruplex (rG4) structure detection using RTS and SHALiPE assays. Methods Enzymol 2023; 691:63-80. [PMID: 37914452 DOI: 10.1016/bs.mie.2023.06.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2023]
Abstract
RNA G-quadruplexes (rG4s) are non-canonical RNA secondary structures that were first reported several decades ago. Latest studies have suggested that they are widespread in the transcriptomes of diverse species, and they have been demonstrated to have key roles in various fundamental cellular processes. Among the RNA secondary structure probing assays developed recently, Reverse transcriptase stalling (RTS) and selective 2'-hydroxyl acylation analyzed by lithium ion-based primer extension (SHALiPE) enabled the identification and characterization of distinct structural features of an rG4 structure of interest. Herein, we present an experimental protocol describing in detail the procedures involved in the preparation of in vitro transcribed RNAs, buffers, and reagents for RTS and SHALiPE assays, as well as performing RTS and SHALiPE assays, to examine the formation of rG4 and reveal the rG4 structural conformation at nucleotide resolution in vitro. RTS and SHALiPE assays can be performed by an experienced molecular biologist or chemical biologist with a basic understanding of nucleic acids. The duration for the preparation of in vitro transcription and RNA preparation is around 2 days, and the duration for RTS and SHALiPE assays is approximately 5 h.
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Affiliation(s)
- Kaixin Lyu
- Department of Chemistry and State Key Laboratory of Marine Pollution, City University of Hong Kong, Hong Kong SAR, P.R. China
| | - Chun Kit Kwok
- Department of Chemistry and State Key Laboratory of Marine Pollution, City University of Hong Kong, Hong Kong SAR, P.R. China; Shenzhen Research Institute of City University of Hong Kong, Shenzhen, China.
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Monsen RC. Higher-order G-quadruplexes in promoters are untapped drug targets. Front Chem 2023; 11:1211512. [PMID: 37351517 PMCID: PMC10282141 DOI: 10.3389/fchem.2023.1211512] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 05/30/2023] [Indexed: 06/24/2023] Open
Abstract
G-quadruplexes (G4s) are four-stranded nucleic acid secondary structures that form within guanine-rich regions of chromatin. G4 motifs are abundant in the genome, with a sizable proportion (∼40%) existing within gene promoter regions. G4s are proven epigenetic features that decorate the promoter landscape as binding centers for transcription factors. Stabilizing or disrupting promoter G4s can directly influence adjacent gene transcription, making G4s attractive as indirect drug targets for hard-to-target proteins, particularly in cancer. However, no G4 ligands have progressed through clinical trials, mostly owing to off targeting effects. A major hurdle in G4 drug discovery is the lack of distinctiveness of the small monomeric G4 structures currently used as receptors. This mini review describes and contrasts monomeric and higher-order G-quadruplex structure and function and provides a rationale for switching focus to the higher-order forms as selective molecular targets. The human telomerase reverse transcriptase (hTERT) core promoter G-quadruplex is then used as a case study that highlights the potential for higher-order G4s as selective indirect inhibitors of hard-to-target proteins in cancer.
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