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DNA Base Excision Repair Intermediates Influence Duplex-Quadruplex Equilibrium. Molecules 2023; 28:molecules28030970. [PMID: 36770637 PMCID: PMC9920732 DOI: 10.3390/molecules28030970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/12/2023] [Accepted: 01/13/2023] [Indexed: 01/21/2023] Open
Abstract
Although genomic DNA is predominantly duplex under physiological conditions, particular sequence motifs can favor the formation of alternative secondary structures, including the G-quadruplex. These structures can exist within gene promoters, telomeric DNA, and regions of the genome frequently found altered in human cancers. DNA is also subject to hydrolytic and oxidative damage, and its local structure can influence the type of damage and its magnitude. Although the repair of endogenous DNA damage by the base excision repair (BER) pathway has been extensively studied in duplex DNA, substantially less is known about repair in non-duplex DNA structures. Therefore, we wanted to better understand the effect of DNA damage and repair on quadruplex structure. We first examined the effect of placing pyrimidine damage products uracil, 5-hydroxymethyluracil, the chemotherapy agent 5-fluorouracil, and an abasic site into the loop region of a 22-base telomeric repeat sequence known to form a G-quadruplex. Quadruplex formation was unaffected by these analogs. However, the activity of the BER enzymes were negatively impacted. Uracil DNA glycosylase (UDG) and single-strand selective monofunctional uracil DNA glycosylase (SMUG1) were inhibited, and apurinic/apyrimidinic endonuclease 1 (APE1) activity was completely blocked. Interestingly, when we performed studies placing DNA repair intermediates into the strand opposite the quadruplex, we found that they destabilized the duplex and promoted quadruplex formation. We propose that while duplex is the preferred configuration, there is kinetic conversion between duplex and quadruplex. This is supported by our studies using a quadruplex stabilizing molecule, pyridostatin, that is able to promote quadruplex formation starting from duplex DNA. Our results suggest how DNA damage and repair intermediates can alter duplex-quadruplex equilibrium.
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2
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Marquevielle J, De Rache A, Vialet B, Morvan E, Mergny JL, Amrane S. G-quadruplex structure of the C. elegans telomeric repeat: a two tetrads basket type conformation stabilized by a non-canonical C-T base-pair. Nucleic Acids Res 2022; 50:7134-7146. [PMID: 35736226 PMCID: PMC9262591 DOI: 10.1093/nar/gkac523] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 05/07/2022] [Accepted: 06/01/2022] [Indexed: 12/24/2022] Open
Abstract
The Caenorhabditis elegans model has greatly contributed to the understanding of the role of G-quadruplexes in genomic instability. The GGCTTA repeats of the C. elegans telomeres resemble the GGGTTA repeats of the human telomeres. However, the comparison of telomeric sequences (Homo sapiens, Tetrahymena, Oxytricha, Bombyx mori and Giardia) revealed that small changes in these repeats can drastically change the topology of the folded G-quadruplex. In the present work we determined the structure adopted by the C. elegans telomeric sequence d[GG(CTTAGG)3]. The investigated C. elegans telomeric sequence is shown to fold into an intramolecular two G-tetrads basket type G-quadruplex structure that includes a C-T base pair in the diagonal loop. This work sheds light on the telomeric structure of the widely used C. elegans animal model.
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Affiliation(s)
- Julien Marquevielle
- Univ. Bordeaux, Inserm U1212, CNRS UMR 5320, ARNA laboratory, 146 rue Léo Saignat F-33000 Bordeaux, France
- Institut Européen de Chimie et Biologie, UMS 3033 US001, CNRS-Université de Bordeaux, 2 rue Robert Escarpit, F-33600 Pessac, France
| | - Aurore De Rache
- Univ. Bordeaux, Inserm U1212, CNRS UMR 5320, ARNA laboratory, 146 rue Léo Saignat F-33000 Bordeaux, France
- Institut Européen de Chimie et Biologie, UMS 3033 US001, CNRS-Université de Bordeaux, 2 rue Robert Escarpit, F-33600 Pessac, France
- Department of Chemistry, UNamur, 61 rue de Bruxelles, B-5000 Namur, Belgium
| | - Brune Vialet
- Univ. Bordeaux, Inserm U1212, CNRS UMR 5320, ARNA laboratory, 146 rue Léo Saignat F-33000 Bordeaux, France
| | - Estelle Morvan
- Institut Européen de Chimie et Biologie, UMS 3033 US001, CNRS-Université de Bordeaux, 2 rue Robert Escarpit, F-33600 Pessac, France
| | - Jean-Louis Mergny
- Univ. Bordeaux, Inserm U1212, CNRS UMR 5320, ARNA laboratory, 146 rue Léo Saignat F-33000 Bordeaux, France
- Institut Européen de Chimie et Biologie, UMS 3033 US001, CNRS-Université de Bordeaux, 2 rue Robert Escarpit, F-33600 Pessac, France
- Laboratoire d’Optique et Biosciences, Ecole Polytechnique, CNRS, INSERM, Institut Polytechnique de Paris, 91128 Palaiseau, France
| | - Samir Amrane
- Univ. Bordeaux, Inserm U1212, CNRS UMR 5320, ARNA laboratory, 146 rue Léo Saignat F-33000 Bordeaux, France
- Institut Européen de Chimie et Biologie, UMS 3033 US001, CNRS-Université de Bordeaux, 2 rue Robert Escarpit, F-33600 Pessac, France
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3
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Devi G, Winnerdy FR, Ang JCY, Lim KW, Phan AT. Four-Layered Intramolecular Parallel G-Quadruplex with Non-Nucleotide Loops: An Ultra-Stable Self-Folded DNA Nano-Scaffold. ACS NANO 2022; 16:533-540. [PMID: 34927423 DOI: 10.1021/acsnano.1c07630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
A four-stranded scaffold of nucleic acids termed G-quadruplex (G4) has found growing applications in nano- and biotechnology. Propeller loops are a hallmark of the most stable intramolecular parallel-stranded G4s. To date, propeller loops have been observed to span only a maximum of three G-tetrad layers. Going beyond that would allow creation of more stable scaffolds useful for building robust nanodevices. Here we investigate the formation of propeller loops spanning more than three layers. We show that native nucleotide sequences are incompatible toward this goal, and we report on synthetic non-nucleotide linkers that form a propeller loop across four layers. With the established linkers, we constructed a four-layered intramolecular parallel-stranded G4, which exhibited ultrahigh thermal stability. Control on loop design would augment the toolbox toward engineering of G4-based nanoscaffolds for diverse applications.
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Affiliation(s)
- Gitali Devi
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Fernaldo Richtia Winnerdy
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Jason Cheng Yu Ang
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Kah Wai Lim
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Anh Tuân Phan
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- NTU Institute of Structural Biology, Nanyang Technological University, Singapore 636921, Singapore
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4
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Balasubramaniyam T, Oh KI, Jin HS, Ahn HB, Kim BS, Lee JH. Non-Canonical Helical Structure of Nucleic Acids Containing Base-Modified Nucleotides. Int J Mol Sci 2021; 22:9552. [PMID: 34502459 PMCID: PMC8430589 DOI: 10.3390/ijms22179552] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 08/27/2021] [Accepted: 08/29/2021] [Indexed: 12/12/2022] Open
Abstract
Chemically modified nucleobases are thought to be important for therapeutic purposes as well as diagnosing genetic diseases and have been widely involved in research fields such as molecular biology and biochemical studies. Many artificially modified nucleobases, such as methyl, halogen, and aryl modifications of purines at the C8 position and pyrimidines at the C5 position, are widely studied for their biological functions. DNA containing these modified nucleobases can form non-canonical helical structures such as Z-DNA, G-quadruplex, i-motif, and triplex. This review summarizes the synthesis of chemically modified nucleotides: (i) methylation, bromination, and arylation of purine at the C8 position and (ii) methylation, bromination, and arylation of pyrimidine at the C5 position. Additionally, we introduce the non-canonical structures of nucleic acids containing these modifications.
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Affiliation(s)
- Thananjeyan Balasubramaniyam
- Department of Chemistry, Gyeongsang National University, Jinju 52828, Gyeongnam, Korea; (T.B.); (K.-I.O.); (H.-S.J.); (H.-B.A.)
- The Research Institute of Natural Science, Gyeongsang National University, Jinju 52828, Gyeongnam, Korea
| | - Kwnag-Im Oh
- Department of Chemistry, Gyeongsang National University, Jinju 52828, Gyeongnam, Korea; (T.B.); (K.-I.O.); (H.-S.J.); (H.-B.A.)
- The Research Institute of Natural Science, Gyeongsang National University, Jinju 52828, Gyeongnam, Korea
| | - Ho-Seong Jin
- Department of Chemistry, Gyeongsang National University, Jinju 52828, Gyeongnam, Korea; (T.B.); (K.-I.O.); (H.-S.J.); (H.-B.A.)
| | - Hye-Bin Ahn
- Department of Chemistry, Gyeongsang National University, Jinju 52828, Gyeongnam, Korea; (T.B.); (K.-I.O.); (H.-S.J.); (H.-B.A.)
| | - Byeong-Seon Kim
- The Research Institute of Natural Science, Gyeongsang National University, Jinju 52828, Gyeongnam, Korea
- Department of Chemistry Education, Gyeongsang National University, Jinju 52828, Gyeongnam, Korea
| | - Joon-Hwa Lee
- Department of Chemistry, Gyeongsang National University, Jinju 52828, Gyeongnam, Korea; (T.B.); (K.-I.O.); (H.-S.J.); (H.-B.A.)
- The Research Institute of Natural Science, Gyeongsang National University, Jinju 52828, Gyeongnam, Korea
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5
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Pavlova AV, Kubareva EA, Monakhova MV, Zvereva MI, Dolinnaya NG. Impact of G-Quadruplexes on the Regulation of Genome Integrity, DNA Damage and Repair. Biomolecules 2021; 11:1284. [PMID: 34572497 PMCID: PMC8472537 DOI: 10.3390/biom11091284] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 08/19/2021] [Accepted: 08/25/2021] [Indexed: 12/13/2022] Open
Abstract
DNA G-quadruplexes (G4s) are known to be an integral part of the complex regulatory systems in both normal and pathological cells. At the same time, the ability of G4s to impede DNA replication plays a critical role in genome integrity. This review summarizes the results of recent studies of G4-mediated genomic and epigenomic instability, together with associated DNA damage and repair processes. Although the underlying mechanisms remain to be elucidated, it is known that, among the proteins that recognize G4 structures, many are linked to DNA repair. We analyzed the possible role of G4s in promoting double-strand DNA breaks, one of the most deleterious DNA lesions, and their repair via error-prone mechanisms. The patterns of G4 damage, with a focus on the introduction of oxidative guanine lesions, as well as their removal from G4 structures by canonical repair pathways, were also discussed together with the effects of G4s on the repair machinery. According to recent findings, there must be a delicate balance between G4-induced genome instability and G4-promoted repair processes. A broad overview of the factors that modulate the stability of G4 structures in vitro and in vivo is also provided here.
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Affiliation(s)
- Anzhela V. Pavlova
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia; (M.I.Z.); (N.G.D.)
| | - Elena A. Kubareva
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia; (E.A.K.); (M.V.M.)
| | - Mayya V. Monakhova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia; (E.A.K.); (M.V.M.)
| | - Maria I. Zvereva
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia; (M.I.Z.); (N.G.D.)
| | - Nina G. Dolinnaya
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia; (M.I.Z.); (N.G.D.)
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6
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Bielskutė S, Plavec J, Podbevšek P. Oxidative lesions modulate G-quadruplex stability and structure in the human BCL2 promoter. Nucleic Acids Res 2021; 49:2346-2356. [PMID: 33638996 PMCID: PMC7913773 DOI: 10.1093/nar/gkab057] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 01/08/2021] [Accepted: 01/22/2021] [Indexed: 01/08/2023] Open
Abstract
Misregulation of BCL2 expression has been observed with many diseases and is associated with cellular exposure to reactive oxygen species. A region upstream of the P1 promoter in the human BCL2 gene plays a major role in regulating transcription. This G/C-rich region is highly polymorphic and capable of forming G-quadruplex structures. Herein we report that an oxidative event simulated with an 8-oxo-7,8-dihydroguanine (oxoG) substitution within a long G-tract results in a reduction of structural polymorphism. Surprisingly, oxoG within a 25-nt construct boosts thermal stability of the resulting G-quadruplex. This is achieved by distinct hydrogen bonding properties of oxoG, which facilitate formation of an antiparallel basket-type G-quadruplex with a three G-quartet core and a G·oxoG·C base triad. While oxoG has previously been considered detrimental for G-quadruplex formation, its stabilizing effect within a promoter described in this study suggests a potential novel regulatory role of oxidative stress in general and specifically in BCL2 gene transcription.
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Affiliation(s)
- Stasė Bielskutė
- Slovenian NMR Center, National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia
| | - Janez Plavec
- Slovenian NMR Center, National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia.,EN-FIST Center of Excellence, Trg OF 13, SI-1000 Ljubljana, Slovenia.,Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI-1000 Ljubljana, Slovenia
| | - Peter Podbevšek
- Slovenian NMR Center, National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia
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7
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Sengupta P, Bose D, Chatterjee S. The Molecular Tête-à-Tête between G-Quadruplexes and the i-motif in the Human Genome. Chembiochem 2021; 22:1517-1537. [PMID: 33355980 DOI: 10.1002/cbic.202000703] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 12/16/2020] [Indexed: 12/22/2022]
Abstract
G-Quadruplex (GQ) and i-motif structures are the paradigmatic examples of nonclassical tetrastranded nucleic acids having multifarious biological functions and widespread applications in therapeutics and material science. Recently, tetraplexes emerged as promising anticancer targets due to their structural robustness, gene-regulatory roles, and predominant distribution at specific loci of oncogenes. However, it is arguable whether the i-motif evolves in the complementary single-stranded region after GQ formation in its opposite strand and vice versa. In this review, we address the prerequisites and significance of the simultaneous and/or mutually exclusive formation of GQ and i-motif structures at complementary and sequential positions in duplexes in the cellular milieu. We discussed how their dynamic interplay Sets up cellular homeostasis and exacerbates carcinogenesis. The review gives insights into the spatiotemporal formation of GQ and i-motifs that could be harnessed to design different types of reporter systems and diagnostic platforms for potential bioanalytical and therapeutic intervention.
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Affiliation(s)
- Pallabi Sengupta
- Department of Biophysics, Bose Institute, Centenary Campus, P-1/12, C.I.T. Scheme VIIM, Kankurgachi, Kolkata, 700054, West Bengal, India
| | - Debopriya Bose
- Department of Biophysics, Bose Institute, Centenary Campus, P-1/12, C.I.T. Scheme VIIM, Kankurgachi, Kolkata, 700054, West Bengal, India
| | - Subhrangsu Chatterjee
- Department of Biophysics, Bose Institute, Centenary Campus, P-1/12, C.I.T. Scheme VIIM, Kankurgachi, Kolkata, 700054, West Bengal, India
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8
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Reddy Sannapureddi RK, Mohanty MK, Gautam AK, Sathyamoorthy B. Characterization of DNA G-quadruplex Topologies with NMR Chemical Shifts. J Phys Chem Lett 2020; 11:10016-10022. [PMID: 33179931 DOI: 10.1021/acs.jpclett.0c02969] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
G-quadruplexes are nucleic acid motifs formed by stacking of guanosine-tetrad pseudoplanes. They perform varied biological roles, and their distinctive structural features enable diverse applications. High-resolution structural characterization of G-quadruplexes is often time-consuming and expensive, calling for effective methods. Herein, we develop NMR chemical shifts and machine learning-based methodology that allows direct, rapid, and reliable analysis of canonical three-plane DNA G-quadruplexes sans isotopic enrichment. We show, for the first time, that each unique topology enforces a specific distribution of glycosidic torsion angles. Newly acquired carbon chemical shifts are exquisite probes for the dihedral angle distribution and provide immediate and unambiguous backbone topology assignment. The support vector machine learning methodology aids resonance assignment by providing plane indices for tetrad-forming guanosines. We further demonstrate the robustness by successful application of the methodology to a sequence that folds in two dissimilar topologies under different ionic conditions, providing its first atomic-level characterization.
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Affiliation(s)
| | - Manish Kumar Mohanty
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Madhya Pradesh 462066, India
| | - Anoop Kumar Gautam
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Madhya Pradesh 462066, India
| | - Bharathwaj Sathyamoorthy
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Madhya Pradesh 462066, India
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9
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Reina C, Cavalieri V. Epigenetic Modulation of Chromatin States and Gene Expression by G-Quadruplex Structures. Int J Mol Sci 2020; 21:E4172. [PMID: 32545267 PMCID: PMC7312119 DOI: 10.3390/ijms21114172] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 06/07/2020] [Accepted: 06/10/2020] [Indexed: 02/07/2023] Open
Abstract
G-quadruplexes are four-stranded helical nucleic acid structures formed by guanine-rich sequences. A considerable number of studies have revealed that these noncanonical structural motifs are widespread throughout the genome and transcriptome of numerous organisms, including humans. In particular, G-quadruplexes occupy strategic locations in genomic DNA and both coding and noncoding RNA molecules, being involved in many essential cellular and organismal functions. In this review, we first outline the fundamental structural features of G-quadruplexes and then focus on the concept that these DNA and RNA structures convey a distinctive layer of epigenetic information that is critical for the complex regulation, either positive or negative, of biological activities in different contexts. In this framework, we summarize and discuss the proposed mechanisms underlying the functions of G-quadruplexes and their interacting factors. Furthermore, we give special emphasis to the interplay between G-quadruplex formation/disruption and other epigenetic marks, including biochemical modifications of DNA bases and histones, nucleosome positioning, and three-dimensional organization of chromatin. Finally, epigenetic roles of RNA G-quadruplexes in post-transcriptional regulation of gene expression are also discussed. Undoubtedly, the issues addressed in this review take on particular importance in the field of comparative epigenetics, as well as in translational research.
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Affiliation(s)
- Chiara Reina
- Department of Health Promotion, Mother and Child Care, Internal Medicine and Medical Specialties (PROMISE), University of Palermo, 90127 Palermo, Italy;
| | - Vincenzo Cavalieri
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, 90128 Palermo, Italy
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10
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Wang ZF, Li MH, Chu IT, Winnerdy FR, Phan AT, Chang TC. Cytosine epigenetic modification modulates the formation of an unprecedented G4 structure in the WNT1 promoter. Nucleic Acids Res 2020; 48:1120-1130. [PMID: 31912153 PMCID: PMC7026657 DOI: 10.1093/nar/gkz1207] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 12/09/2019] [Accepted: 12/18/2019] [Indexed: 12/16/2022] Open
Abstract
Time-resolved imino proton nuclear magnetic resonance spectra of the WT22m sequence d(GGGCCACCGGGCAGTGGGCGGG), derived from the WNT1 promoter region, revealed an intermediate G-quadruplex G4(I) structure during K+-induced conformational transition from an initial hairpin structure to the final G4(II) structure. Moreover, a single-base C-to-T mutation at either position C4 or C7 of WT22m could lock the intermediate G4(I) structure without further conformational change to the final G4(II) structure. Surprisingly, we found that the intermediate G4(I) structure is an atypical G4 structure, which differs from a typical hybrid G4 structure of the final G4(II) structure. Further studies of modified cytosine analogues associated with epigenetic regulation indicated that slight modification on a cytosine could modulate G4 structure. A simplified four-state transition model was introduced to describe such conformational transition and disclose the possible mechanism for G4 structural selection caused by cytosine modification.
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Affiliation(s)
- Zi-Fu Wang
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan, R.O.C
| | - Ming-Hao Li
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan, R.O.C
| | - I-Te Chu
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan, R.O.C.,Department of Chemistry, National Taiwan University, Taipei 106, Taiwan, R.O.C
| | - Fernaldo R Winnerdy
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Anh T Phan
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.,NTU Institute of Structural Biology, Nanyang Technological University, Singapore 636921, Singapore
| | - Ta-Chau Chang
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan, R.O.C.,Department of Chemistry, National Taiwan University, Taipei 106, Taiwan, R.O.C
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11
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Fleming AM, Burrows CJ. Interplay of Guanine Oxidation and G-Quadruplex Folding in Gene Promoters. J Am Chem Soc 2020; 142:1115-1136. [PMID: 31880930 PMCID: PMC6988379 DOI: 10.1021/jacs.9b11050] [Citation(s) in RCA: 91] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Living in an oxygen atmosphere demands an ability to thrive in the presence of reactive oxygen species (ROS). Aerobic organisms have successfully found solutions to the oxidative threats imposed by ROS by evolving an elaborate detoxification system, upregulating ROS during inflammation, and utilizing ROS as messenger molecules. In this Perspective, recent studies are discussed that demonstrate ROS as signaling molecules for gene regulation by combining two emergent properties of the guanine (G) heterocycle in DNA, namely, oxidation sensitivity and a propensity for G-quadruplex (G4) folding, both of which depend upon sequence context. In human gene promoters, this results from an elevated 5'-GG-3' dinucleotide frequency and GC enrichment near transcription start sites. Oxidation of DNA by ROS drives conversion of G to 8-oxo-7,8-dihydroguanine (OG) to mark target promoters for base excision repair initiated by OG-glycosylase I (OGG1). Sequence-dependent mechanisms for gene activation are available to OGG1 to induce transcription. Either OGG1 releases OG to yield an abasic site driving formation of a non-canonical fold, such as a G4, to be displayed to apurinic/apyrimidinic 1 (APE1) and stalling on the fold to recruit activating factors, or OGG1 binds OG and facilitates activator protein recruitment. The mechanisms described drive induction of stress response, DNA repair, or estrogen-induced genes, and these pathways are novel potential anticancer targets for therapeutic intervention. Chemical concepts provide a framework to discuss the regulatory or possible epigenetic potential of the OG modification in DNA, in which DNA "damage" and non-canonical folds collaborate to turn on or off gene expression. The next steps for scientific discovery in this growing field are discussed.
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Affiliation(s)
- Aaron M. Fleming
- 315 South 1400 East, Dept. of Chemistry, University of Utah, Salt Lake City, UT 84112-0850, USA
| | - Cynthia J. Burrows
- 315 South 1400 East, Dept. of Chemistry, University of Utah, Salt Lake City, UT 84112-0850, USA
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12
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Chawla M, Minenkov Y, Vu KB, Oliva R, Cavallo L. Structural and Energetic Impact of Non-natural 7-Deaza-8-azaguanine, 7-Deaza-8-azaisoguanine, and Their 7-Substituted Derivatives on Hydrogen-Bond Pairing with Cytosine and Isocytosine. Chembiochem 2019; 20:2262-2270. [PMID: 30983115 DOI: 10.1002/cbic.201900245] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Indexed: 12/12/2022]
Abstract
The impact of 7-deaza-8-azaguanine (DAG) and 7-deaza-8-azaisoguanine (DAiG) modifications on the geometry and stability of the G:C Watson-Crick (cWW) base pair and the G:iC and iG:C reverse Watson-Crick (tWW) base pairs has been characterized theoretically. In addition, the effect on the same base pairs of seven C7-substituted DAG and DAiG derivatives, some of which have been previously experimentally characterized, has been investigated. Calculations indicate that all of these modifications have a negligible impact on the geometry of the above base pairs, and that modification of the heterocycle skeleton has a small impact on the base-pair interaction energies. Instead, base-pair interaction energies are dependent on the nature of the C7 substituent. For the 7-substituted DAG-C cWW systems, a linear correlation between the base-pair interaction energy and the Hammett constant of the 7-substituent is found, with higher interaction energies corresponding to more electron-withdrawing substituents. Therefore, the explored modifications are expected to be accommodated in both parallel and antiparallel nucleic acid duplexes without perturbing their geometry, while the strength of a base pair (and duplex) featuring a DAG modification can, in principle, be tuned by incorporating different substituents at the C7 position.
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Affiliation(s)
- Mohit Chawla
- King Abdullah University of Science and Technology (KAUST), Physical Sciences and Engineering Division, Kaust Catalysis Center, Thuwal, 23955-6900, Saudi Arabia
| | - Yury Minenkov
- Moscow Institute of Physics and Technology, Institutskiy Pereulok 9, Dolgoprudny, Moscow Region, 141700, Russia
| | - Khanh B Vu
- NTT Hi-Tech Institute, Nguyen Tat Thanh University, 298-300A Nguyen Tat Thanh Street, Ho Chi Minh City, Vietnam
| | - Romina Oliva
- Department of Sciences and Technologies, University Parthenope of Naples, Centro Direzionale Isola C4, 80143, Naples, Italy
| | - Luigi Cavallo
- King Abdullah University of Science and Technology (KAUST), Physical Sciences and Engineering Division, Kaust Catalysis Center, Thuwal, 23955-6900, Saudi Arabia
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13
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Bielskutė S, Plavec J, Podbevšek P. Impact of Oxidative Lesions on the Human Telomeric G-Quadruplex. J Am Chem Soc 2019; 141:2594-2603. [PMID: 30657306 PMCID: PMC6727377 DOI: 10.1021/jacs.8b12748] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
![]()
Telomere
attrition is closely associated with cell aging and exposure
to reactive oxygen species (ROS). While oxidation products of nucleotides
have been studied extensively in the past, the underlying secondary/tertiary
structural changes in DNA remain poorly understood. In this work,
we systematically probed guanine positions in the human telomeric
oligonucleotide sequence (hTel) by substitutions with the major product
of ROS, 8-oxo-7,8-dihydroguanine (oxoG), and evaluated
the G-quadruplex forming ability of such oligonucleotides. Due to
reduced hydrogen-bonding capability caused by oxoG, a loss
of G-quadruplex structure was observed for most oligonucleotides containing
oxidative lesions. However, some positions in the hTel sequence were
found to tolerate substitutions with oxoG. Due to oxoG’s preference for the syn conformation, distinct responses were observed when replacing guanines
with different glycosidic conformations. Accommodation of oxoG at sites originally in syn or anti in nonsubstituted hTel G-quadruplex requires a minor structural
rearrangement or a major conformational shift, respectively. The system
responds by retaining or switching to a fold where oxoG
is in syn conformation. Most importantly, these G-quadruplex
structures are still stable at physiological temperatures and should
be considered detrimental in higher-order telomere structures.
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Affiliation(s)
- Stasė Bielskutė
- Slovenian NMR Center , National Institute of Chemistry , Hajdrihova 19 , SI-1000 Ljubljana , Slovenia
| | - Janez Plavec
- Slovenian NMR Center , National Institute of Chemistry , Hajdrihova 19 , SI-1000 Ljubljana , Slovenia.,EN-FIST Center of Excellence , Trg OF 13 , SI-1000 Ljubljana , Slovenia.,Faculty of Chemistry and Chemical Technology , University of Ljubljana , Večna pot 113 , SI-1000 Ljubljana , Slovenia
| | - Peter Podbevšek
- Slovenian NMR Center , National Institute of Chemistry , Hajdrihova 19 , SI-1000 Ljubljana , Slovenia.,EN-FIST Center of Excellence , Trg OF 13 , SI-1000 Ljubljana , Slovenia
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14
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Redstone SCJ, Fleming AM, Burrows CJ. Oxidative Modification of the Potential G-Quadruplex Sequence in the PCNA Gene Promoter Can Turn on Transcription. Chem Res Toxicol 2019; 32:437-446. [PMID: 30604962 DOI: 10.1021/acs.chemrestox.8b00332] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Because of its low redox potential, guanine (G) is the most frequent site of oxidation in the genome. Metabolic processes generate reactive oxygen species (ROS) that can oxidize G to yield 8-oxo-7,8-dihydroguanine (OG) as a key two-electron oxidation product. In a genome, G-rich sites including many gene promoters are sensitive to oxidative modification, and some of these regions have the propensity to form G-quadruplexes (G4s). Recently, OG formation in G-rich gene promoters was demonstrated to regulate mRNA expression via the base excision repair (BER) pathway. The proliferating cell nuclear antigen ( PCNA) gene was previously found to be activated by metabolic ROS, and the gene has a five G-track potential G4 in the coding strand of its promoter. Herein, we demonstrated the ability for four G runs of the PCNA promoter sequence to adopt a parallel-stranded G4. Next, we identified G nucleotides in the PCNA G4 sequence sensitive to oxidative modification. The G oxidation product OG and its initial BER product, an abasic site, were synthetically incorporated into the four- and five-track PCNA sequences at the sensitive sites followed by interrogation of G4 folding by five methods. We found the modifications impacted the G4 folds with positional dependency. Additionally, the fifth G track maintained the stability of the modified G4s by extrusion of the oxidatively modified G run. Finally, we synthetically inserted a portion of the promoter into a reporter plasmid with OG at select oxidation-prone positions to monitor expression in human glioblastoma cells. Our results demonstrate that OG formation in the context of the PCNA G4 can lead to increased gene expression consistent with the previous studies identifying that metabolic ROS activates transcription of the gene. This study provides another example of a G4 with the potential to serve as a regulatory agent for gene expression upon G oxidation.
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Affiliation(s)
- Samuel C J Redstone
- Department of Chemistry , University of Utah , Salt Lake City , Utah 84112-0850 , United States
| | - Aaron M Fleming
- Department of Chemistry , University of Utah , Salt Lake City , Utah 84112-0850 , United States
| | - Cynthia J Burrows
- Department of Chemistry , University of Utah , Salt Lake City , Utah 84112-0850 , United States
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15
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Zhu J, Fleming AM, Burrows CJ. The RAD17 Promoter Sequence Contains a Potential Tail-Dependent G-Quadruplex That Downregulates Gene Expression upon Oxidative Modification. ACS Chem Biol 2018; 13:2577-2584. [PMID: 30063821 DOI: 10.1021/acschembio.8b00522] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Our laboratory has recently proposed that the oxidation of guanine (G) to 8-oxo-7,8-dihydroguanine (OG) in G-rich promoter regions of DNA repair genes can serve as a regulatory mechanism of gene transcription. These regions also have the potential to fold into G-quadruplexes (G4). The human RAD17 promoter sequence has such a region in the template strand of the gene. In this work, the potential G-quadruplex sequence (PQS) of the RAD17 gene promoter was analyzed in different sequence contexts. With two extra nucleotides of the native sequence on either side of the G4, the structure was found to fold into a hybrid-like G4, similar to the hybrid-1 fold that the human telomere sequence can adopt. With only one nucleotide on either side of the PQS, the topology of the structure was observed to be mixed, and without extra nucleotides on the ends, the sequence adopted a parallel fold. Next, the sequence was studied with synthetic incorporation of the oxidative modification OG into specific sites and installed into the promoter of plasmids with a luciferase gene. These plasmids were transfected into a human cell line to observe the effect of the G4s on transcription. The RAD17 PQS was found to decrease luciferase expression with the presence of OG that is consistent with RAD17 expression under oxidative stress. This serves as an example of how oxidative modification could affect transcription in the context of a G4.
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Affiliation(s)
- Judy Zhu
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112-0850, United States
| | - Aaron M. Fleming
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112-0850, United States
| | - Cynthia J. Burrows
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112-0850, United States
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16
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Karg B, Weisz K. Loop Length Affects Syn-Anti Conformational Rearrangements in Parallel G-Quadruplexes. Chemistry 2018; 24:10246-10252. [PMID: 29756658 DOI: 10.1002/chem.201801851] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2018] [Revised: 05/12/2018] [Indexed: 01/24/2023]
Abstract
A G-quadruplex forming sequence from the MYC promoter region was modified with syn-favoring 8-bromo-2'-deoxyguanosine residues. Depending on the number and position of modifications in the intramolecular parallel G-quadruplex, substitutions with the bromoguanosine analogue at the 5'-tetrad induce conformational rearrangements with concerted all-anti to all-syn transitions for all residues of the modified G-quartet. No unfavorable steric interactions of the C8-substituents in the medium grooves are apparent in the high-resolution structure as determined for a tetrasubstituted MYC quadruplex that exclusively forms the all-syn isomer. In contrast, considerable steric clashes with 5'-phosphate oxygen atoms for those analogues that follow a less flexible 1-nucleotide loop in the native all-anti conformation seem to constitute the major driving force for the tetrad inversion and allow for the rational design of appropriately substituted sequences. Correlations found between the population of species subjected to a tetrad flip and melting temperatures indicate that more effective conformational transitions are compromised by lower thermal stabilities of the modified parallel quadruplexes.
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Affiliation(s)
- Beatrice Karg
- Institute of Biochemistry, Ernst-Moritz-Arndt University Greifswald, Felix-Hausdorff-Str. 4, 17487, Greifswald, Germany
| | - Klaus Weisz
- Institute of Biochemistry, Ernst-Moritz-Arndt University Greifswald, Felix-Hausdorff-Str. 4, 17487, Greifswald, Germany
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17
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Omaga CA, Fleming AM, Burrows CJ. The Fifth Domain in the G-Quadruplex-Forming Sequence of the Human NEIL3 Promoter Locks DNA Folding in Response to Oxidative Damage. Biochemistry 2018; 57:2958-2970. [PMID: 29718661 DOI: 10.1021/acs.biochem.8b00226] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
DNA oxidation is an inevitable and usually detrimental process, but the cell is capable of reversing this state because the cell possesses a highly developed set of DNA repair machineries, including the DNA glycosylase NEIL3 that is encoded by the NEIL3 gene. In this work, the G-rich promoter region of the human NEIL3 gene was shown to fold into a dynamic G-quadruplex (G4) structure under nearly physiological conditions using spectroscopic techniques (e.g., nuclear magnetic resonance, circular dichroism, fluorescence, and ultraviolet-visible) and DNA polymerase stop assays. The presence of 8-oxo-7,8-dihydroguanine (OG) modified the properties of the NEIL3 G4 and entailed the recruitment of the fifth domain to function as a "spare tire", in which an undamaged fifth G-track is swapped for the damaged section of the G4. The polymerase stop assay findings also revealed that owing to its dynamic polymorphism, the NEIL3 G4 is more readily bypassed by DNA polymerase I (Klenow fragment) than well-known oncogene G4s are. This study identifies the NEIL3 promoter possessing a G-rich element that can adopt a G4 fold, and when OG is incorporated, the sequence can lock into a more stable G4 fold via recruitment of the fifth track of Gs.
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Affiliation(s)
- Carla A Omaga
- Department of Chemistry , University of Utah , Salt Lake City , Utah 84112-0850 , United States
| | - Aaron M Fleming
- Department of Chemistry , University of Utah , Salt Lake City , Utah 84112-0850 , United States
| | - Cynthia J Burrows
- Department of Chemistry , University of Utah , Salt Lake City , Utah 84112-0850 , United States
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18
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Dvořáková Z, Vorlíčková M, Renčiuk D. Spectroscopic insights into quadruplexes of five-repeat telomere DNA sequences upon G-block damage. Biochim Biophys Acta Gen Subj 2017; 1861:2750-2757. [DOI: 10.1016/j.bbagen.2017.07.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 06/16/2017] [Accepted: 07/24/2017] [Indexed: 11/26/2022]
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19
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Lech CJ, Phan AT. Ball with hair: modular functionalization of highly stable G-quadruplex DNA nano-scaffolds through N2-guanine modification. Nucleic Acids Res 2017; 45:6265-6274. [PMID: 28499037 PMCID: PMC5499775 DOI: 10.1093/nar/gkx243] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 05/10/2017] [Indexed: 12/13/2022] Open
Abstract
Functionalized nanoparticles have seen valuable applications, particularly in the delivery of therapeutic and diagnostic agents in biological systems. However, the manufacturing of such nano-scale systems with the consistency required for biological application can be challenging, as variation in size and shape have large influences in nanoparticle behavior in vivo. We report on the development of a versatile nano-scaffold based on the modular functionalization of a DNA G-quadruplex. DNA sequences are functionalized in a modular fashion using well-established phosphoramidite chemical synthesis with nucleotides containing modification of the amino (N2) position of the guanine base. In physiological conditions, these sequences fold into well-defined G-quadruplex structures. The resulting DNA nano-scaffolds are thermally stable, consistent in size, and functionalized in a manner that allows for control over the density and relative orientation of functional chemistries on the nano-scaffold surface. Various chemistries including small modifications (N2-methyl-guanine), bulky aromatic modifications (N2-benzyl-guanine), and long chain-like modifications (N2-6-amino-hexyl-guanine) are tested and are found to be generally compatible with G-quadruplex formation. Furthermore, these modifications stabilize the G-quadruplex scaffold by 2.0–13.3 °C per modification in the melting temperature, with concurrent modifications producing extremely stable nano-scaffolds. We demonstrate the potential of this approach by functionalizing nano-scaffolds for use within the biotin–avidin conjugation approach.
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Affiliation(s)
- Christopher Jacques Lech
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371
| | - Anh Tuân Phan
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371
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20
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Sagi J. In What Ways Do Synthetic Nucleotides and Natural Base Lesions Alter the Structural Stability of G-Quadruplex Nucleic Acids? J Nucleic Acids 2017; 2017:1641845. [PMID: 29181193 PMCID: PMC5664352 DOI: 10.1155/2017/1641845] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 08/15/2017] [Indexed: 01/03/2023] Open
Abstract
Synthetic analogs of natural nucleotides have long been utilized for structural studies of canonical and noncanonical nucleic acids, including the extensively investigated polymorphic G-quadruplexes (GQs). Dependence on the sequence and nucleotide modifications of the folding landscape of GQs has been reviewed by several recent studies. Here, an overview is compiled on the thermodynamic stability of the modified GQ folds and on how the stereochemical preferences of more than 70 synthetic and natural derivatives of nucleotides substituting for natural ones determine the stability as well as the conformation. Groups of nucleotide analogs only stabilize or only destabilize the GQ, while the majority of analogs alter the GQ stability in both ways. This depends on the preferred syn or anti N-glycosidic linkage of the modified building blocks, the position of substitution, and the folding architecture of the native GQ. Natural base lesions and epigenetic modifications of GQs explored so far also stabilize or destabilize the GQ assemblies. Learning the effect of synthetic nucleotide analogs on the stability of GQs can assist in engineering a required stable GQ topology, and exploring the in vitro action of the single and clustered natural base damage on GQ architectures may provide indications for the cellular events.
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Affiliation(s)
- Janos Sagi
- Rimstone Laboratory, RLI, Carlsbad, CA 92010, USA
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21
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Rigo R, Palumbo M, Sissi C. G-quadruplexes in human promoters: A challenge for therapeutic applications. Biochim Biophys Acta Gen Subj 2016; 1861:1399-1413. [PMID: 28025083 DOI: 10.1016/j.bbagen.2016.12.024] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 12/21/2016] [Accepted: 12/22/2016] [Indexed: 12/19/2022]
Abstract
BACKGROUND G-rich sequences undergo unique structural equilibria to form G-quadruplexes (G4) both in vitro and in cell systems. Several pathologies emerged to be directly related to G4 occurrence at defined genomic portions. Additionally, G-rich sequences are significantly represented around transcription start sites (TSS) thus leading to the hypothesis of a gene regulatory function for G4. Thus, the tuning of G4 formation has been proposed as a new powerful tool to regulate gene expression to treat related pathologies. However, up-to date this approach did not provide any new really efficient treatment. SCOPE OF REVIEW Here, we summarize the most recent advances on the correlation between the structural features of G4 in human promoters and the role these systems physiologically exert. In particular we focus on the effect of G4 localization among cell compartments and along the promoters in correlation with protein interaction networks and epigenetic state. Finally the intrinsic structural features of G4 at promoters are discussed to unveil the contribution of different G4 structural modules in this complex architecture. MAJOR CONCLUSIONS It emerges that G4s play several roles in the intriguing and complex mechanism of gene expression, being able to produce opposite effects on the same target. This reflects the occurrence of a highly variegate network of several components working simultaneously. GENERAL SIGNIFICANCE The resulting picture is still fuzzy but some points of strength are definitely emerging, which prompts all of us to strengthen our efforts in view of a selective control of gene expression through G4 modulation. This article is part of a Special Issue entitled "G-quadruplex" Guest Editor: Dr. Concetta Giancola and Dr. Daniela Montesarchio.
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Affiliation(s)
- Riccardo Rigo
- Dept. of Pharmaceutical and Pharmacological Sciences, University of Padova, v. Marzolo, 5, 35131 Padova, Italy
| | - Manlio Palumbo
- Dept. of Pharmaceutical and Pharmacological Sciences, University of Padova, v. Marzolo, 5, 35131 Padova, Italy
| | - Claudia Sissi
- Dept. of Pharmaceutical and Pharmacological Sciences, University of Padova, v. Marzolo, 5, 35131 Padova, Italy.
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22
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Pinto B, Rusciano G, D'Errico S, Borbone N, Sasso A, Piccialli V, Mayol L, Oliviero G, Piccialli G. Synthesis and label free characterization of a bimolecular PNA homo quadruplex. Biochim Biophys Acta Gen Subj 2016; 1861:1222-1228. [PMID: 27913190 DOI: 10.1016/j.bbagen.2016.11.037] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 11/25/2016] [Accepted: 11/26/2016] [Indexed: 12/31/2022]
Abstract
BACKGROUND G-quadruplex DNA is involved in many physiological and pathological processes. Both clinical and experimental studies on DNA G-quadruplexes are slowed down by their enzymatic instability. In this frame, more stable chemically modified analogs are needed. METHODS The bis-end-linked-(gggt)2 PNA molecule (BEL-PNA) was synthesized using in solution and solid phase synthetic approaches. Quadruplex formation was assessed by circular dichroism (CD) and surface enhanced Raman scattering (SERS). RESULTS An unprecedented bimolecular PNA homo quadruplex is here reported. To achieve this goal, we developed a bifunctional linker that once functionalized with gggt PNA strands and annealed in K+ buffer allowed the obtainment of a PNA homo quadruplex. The identification of the strong SERS band at ~1481cm-1, attributable to vibrations involving the quadruplex diagnostic Hoogsteen type hydrogen bonds, confirmed the formation of the PNA homo quadruplex. CONCLUSIONS By tethering two G-rich PNA strands to the two ends of a suitable bifunctional linker it is possible to obtain bimolecular PNA homo quadruplexes after annealing in K+-containing buffers. The formation of such CD-unfriendly complexes can be monitored, even at low concentrations, by using the SERS technique. GENERAL SIGNIFICANCE Given the importance of DNA G-quadruplexes in medicine and nanotechnology, the obtainment of G-quadruplex analogs provided with enhanced enzymatic stability, and their monitoring by highly sensitive label-free techniques are of the highest importance. This article is part of a Special Issue entitled "G-quadruplex" Guest Editor: Dr. Concetta Giancola and Dr. Daniela Montesarchio.
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Affiliation(s)
- Brunella Pinto
- Dipartimento di Farmacia, Università degli Studi di Napoli Federico II, 80131 Napoli, Italy
| | - Giulia Rusciano
- Dipartimento di Scienze Fisiche, Università degli Studi di Napoli Federico II, 80126 Napoli, Italy
| | - Stefano D'Errico
- Dipartimento di Farmacia, Università degli Studi di Napoli Federico II, 80131 Napoli, Italy
| | - Nicola Borbone
- Dipartimento di Farmacia, Università degli Studi di Napoli Federico II, 80131 Napoli, Italy
| | - Antonio Sasso
- Dipartimento di Scienze Fisiche, Università degli Studi di Napoli Federico II, 80126 Napoli, Italy
| | - Vincenzo Piccialli
- Dipartimento di Scienze Chimiche, Università degli Studi di Napoli Federico II, 80126 Napoli, Italy
| | - Luciano Mayol
- Dipartimento di Farmacia, Università degli Studi di Napoli Federico II, 80131 Napoli, Italy
| | - Giorgia Oliviero
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università degli Studi di Napoli Federico II, 80131 Napoli, Italy.
| | - Gennaro Piccialli
- Dipartimento di Farmacia, Università degli Studi di Napoli Federico II, 80131 Napoli, Italy; CNR, Institute of Protein Biochemistry, 80131 Napoli, Italy.
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23
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Zhao Z, Lin F, Ye H, Huang R, Xu X. Effects of modified-guanosine on the stability of G-triplex. Tetrahedron Lett 2016. [DOI: 10.1016/j.tetlet.2016.10.052] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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24
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The effect of l-thymidine, acyclic thymine and 8-bromoguanine on the stability of model G-quadruplex structures. Biochim Biophys Acta Gen Subj 2016; 1861:1205-1212. [PMID: 27705754 DOI: 10.1016/j.bbagen.2016.09.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Revised: 09/27/2016] [Accepted: 09/28/2016] [Indexed: 12/13/2022]
Abstract
BACKGROUND Guanine-rich oligonucleotides are capable of forming tetrahelical structures known as G-quadruplexes with interesting biological properties. We have investigated the effects of site-specific substitution in the loops and in the tetrads model G-quadruplexes using thymine glycol nucleic acid (GNA) units, l-thymidine and 8-Br-2'-deoxyguanosine. METHODS Modified oligonucleotides were chemically synthesized and spectroscopic techniques were used to determine the relative stability of the modified G-quadruplex. The double 8-BrdG-modified quadruplexes were further characterized by Nuclear Magnetic Resonance. Binding to thrombin of selected quadruplex was analyzed by gel electrophoresis retention assay. RESULTS The most interesting results were found with a 8-bromoG substitution that had the larger stabilization of the quadruplex. NMR studies indicate a tight relationship between the loops and the tetrads to accommodate 8-bromoG modifications within the TBA. CONCLUSIONS The substitutions of loop positions with GNA T affect the TBA stability except for single modification in T7 position. Single l-thymidine substitutions produced destabilization of TBA. Larger changes on quadruplex stability are observed with the use of 8-bromoG finding a single substitution with the highest thermal stabilization found in thrombin binding aptamers modified at the guanine residues and having good affinity for thrombin. Double 8-BrdG modification in anti positions of different tetrads produce a conformational flip from syn to anti conformation of 8-Br-dG to favor loop-tetrad interaction and preserve the overall TBA stability. GENERAL SIGNIFICANCE Modified guanine-rich oligonucleotides are valuable tools for the search for G-quadruplex structures with higher thermal stability and may provide compounds with interesting protein-nucleic acid binding properties. This article is part of a Special Issue entitled "G-quadruplex" Guest Editor: Dr. Concetta Giancola and Dr. Daniela Montesarchio.
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25
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Nelissen FHT, Tessari M, Wijmenga SS, Heus HA. Stable isotope labeling methods for DNA. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2016; 96:89-108. [PMID: 27573183 DOI: 10.1016/j.pnmrs.2016.06.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 06/02/2016] [Accepted: 06/02/2016] [Indexed: 06/06/2023]
Abstract
NMR is a powerful method for studying proteins and nucleic acids in solution. The study of nucleic acids by NMR is far more challenging than for proteins, which is mainly due to the limited number of building blocks and unfavorable spectral properties. For NMR studies of DNA molecules, (site specific) isotope enrichment is required to facilitate specific NMR experiments and applications. Here, we provide a comprehensive review of isotope-labeling strategies for obtaining stable isotope labeled DNA as well as specifically stable isotope labeled building blocks required for enzymatic DNA synthesis.
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Affiliation(s)
- Frank H T Nelissen
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, The Netherlands.
| | - Marco Tessari
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, The Netherlands.
| | - Sybren S Wijmenga
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, The Netherlands.
| | - Hans A Heus
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, The Netherlands.
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26
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Virgilio A, Esposito V, Mayol L, Giancola C, Petraccone L, Galeone A. The oxidative damage to the human telomere: effects of 5-hydroxymethyl-2'-deoxyuridine on telomeric G-quadruplex structures. Org Biomol Chem 2016; 13:7421-9. [PMID: 25997822 DOI: 10.1039/c5ob00748h] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
As part of the genome, human telomeric regions can be damaged by the chemically reactive molecules responsible for oxidative DNA damage. Considering that G-quadruplex structures have been proven to occur in human telomere regions, several studies have been devoted to investigating the effect of oxidation products on the properties of these structures. However only investigations concerning the presence in G-quadruplexes of the main oxidation products of deoxyguanosine and deoxyadenosine have appeared in the literature. Here, we investigated the effects of 5-hydroxymethyl-2'-deoxyuridine (5-hmdU), one of the main oxidation products of T, on the physical-chemical properties of the G-quadruplex structures formed by two human telomeric sequences. Collected calorimetric, circular dichroism and electrophoretic data suggest that, in contrast to most of the results on other damage, the replacement of a T with a 5-hmdU results in only negligible effects on structural stability. Reported results and other data from literature suggest a possible protecting effect of the loop residues on the other parts of the G-quadruplexes.
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Affiliation(s)
- Antonella Virgilio
- Dipartimento di Farmacia, Università degli Studi di Napoli "Federico II", Via D. Montesano 49, I-80131 Napoli, Italy.
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27
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An N, Fleming AM, Burrows CJ. Human Telomere G-Quadruplexes with Five Repeats Accommodate 8-Oxo-7,8-dihydroguanine by Looping out the DNA Damage. ACS Chem Biol 2016; 11:500-7. [PMID: 26686913 DOI: 10.1021/acschembio.5b00844] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Inflammation and oxidative stress generate free radicals that oxidize guanine (G) in DNA to 8-oxo-7,8-dihydroguanine (OG), and this reaction is prominent in the G-rich telomere sequence. In telomeres, OG is not efficiently removed by repair pathways allowing its concentration to build, surprisingly without any immediate negative consequences to stability. Herein, OG was synthesized in five repeats of the human telomere sequence (TTAGGG)n, at the 5'-G of the 5'-most, middle, and 3'-most G tracks, representing hotspots for oxidation. These synthetic oligomers were folded in relevant amounts of K(+)/Na(+) to adopt hybrid G-quadruplex folds. The structural impact of OG was assayed by circular dichroism, thermal melting, (1)H NMR, and single-molecule profiling by the α-hemolysin nanopore. On the basis of these results, OG was well accommodated in the five-repeat sequences by looping out the damaged G track to allow the other four tracks to adopt a hybrid G-quadruplex. These results run counter to previous studies with OG in four-repeat telomere sequences that found OG to be highly destabilizing and causing significant reorientation of the fold. When taking a wider view of the human telomere sequence and considering additional repeats, we found OG to cause minimal impact on the structure. The plasticity of this repeat sequence addresses how OG concentrations can increase in telomeres without immediate telomere instability or attrition.
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Affiliation(s)
- Na An
- Department of Chemistry, University of Utah, 315 South 1400
East, Salt Lake City, Utah 84112-0850, United States
| | - Aaron M. Fleming
- 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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Cheong VV, Lech CJ, Heddi B, Phan AT. Inverting the G-Tetrad Polarity of a G-Quadruplex by Using Xanthine and 8-Oxoguanine. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201507034] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Cheong VV, Lech CJ, Heddi B, Phan AT. Inverting the G-Tetrad Polarity of a G-Quadruplex by Using Xanthine and 8-Oxoguanine. Angew Chem Int Ed Engl 2015; 55:160-3. [PMID: 26563582 DOI: 10.1002/anie.201507034] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 09/04/2015] [Indexed: 01/24/2023]
Abstract
G-quadruplexes are four-stranded nucleic acid structures that are built from consecutively stacked guanine tetrad (G-tetrad) assemblies. The simultaneous incorporation of two guanine base lesions, xanthine (X) and 8-oxoguanine (O), within a single G-tetrad of a G-quadruplex was recently shown to lead to the formation of a stable G⋅G⋅X⋅O tetrad. Herein, a judicious introduction of X and O into a human telomeric G-quadruplex-forming sequence is shown to reverse the hydrogen-bond polarity of the modified G-tetrad while preserving the original folding topology. The control exerted over G-tetrad polarity by joint X⋅O modification will be valuable for the design and programming of G-quadruplex structures and their properties.
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Affiliation(s)
- Vee Vee Cheong
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore)
| | - Christopher Jacques Lech
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore)
| | - Brahim Heddi
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore)
| | - Anh Tuân Phan
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore).
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30
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Diverse effects of naturally occurring base lesions on the structure and stability of the human telomere DNA quadruplex. Biochimie 2015; 118:15-25. [DOI: 10.1016/j.biochi.2015.07.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 07/13/2015] [Indexed: 12/28/2022]
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Chawla M, Credendino R, Oliva R, Cavallo L. Structural and Energetic Impact of Non-Natural 7-Deaza-8-Azaadenine and Its 7-Substituted Derivatives on H-Bonding Potential with Uracil in RNA Molecules. J Phys Chem B 2015; 119:12982-9. [PMID: 26389789 DOI: 10.1021/acs.jpcb.5b06861] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Non-natural (synthetic) nucleobases, including 7-ethynyl- and 7-triazolyl-8-aza-7-deazaadenine, have been introduced in RNA molecules for targeted applications, and have been characterized experimentally. However, no theoretical characterization of the impact of these modifications on the structure and energetics of the corresponding H-bonded base pair is available. To fill this gap, we performed quantum mechanics calculations, starting with the analysis of the impact of the 8-aza-7-deaza modification of the adenine skeleton, and we moved then to analyze the impact of the specific substituents on the modified 8-aza-7-deazaadenine. Our analysis indicates that, despite of these severe structural modifications, the H-bonding properties of the modified base pair gratifyingly replicate those of the unmodified base pair. Similar behavior is predicted when the same skeleton modifications are applied to guanine when paired to cytosine. To stress further the H-bonding pairing in the modified adenine-uracil base pair, we explored the impact of strong electron donor and electron withdrawing substituents on the C7 position. Also in this case we found minimal impact on the base pair geometry and energy, confirming the validity of this modification strategy to functionalize RNAs without perturbing its stability and biological functionality.
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Affiliation(s)
- Mohit Chawla
- Physical Sciences and Engineering Division, Kaust Catalysis Center, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia
| | - Raffaele Credendino
- Physical Sciences and Engineering Division, Kaust Catalysis Center, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia
| | - Romina Oliva
- Department of Sciences and Technologies, University Parthenope of Naples , Centro Direzionale Isola C4, I-80143, Naples, Italy
| | - Luigi Cavallo
- Physical Sciences and Engineering Division, Kaust Catalysis Center, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia
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Cheong VV, Heddi B, Lech CJ, Phan AT. Xanthine and 8-oxoguanine in G-quadruplexes: formation of a G·G·X·O tetrad. Nucleic Acids Res 2015; 43:10506-14. [PMID: 26400177 PMCID: PMC4666386 DOI: 10.1093/nar/gkv826] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 07/28/2015] [Indexed: 01/31/2023] Open
Abstract
G-quadruplexes are four-stranded structures built from stacked G-tetrads (G·G·G·G), which are planar cyclical assemblies of four guanine bases interacting through Hoogsteen hydrogen bonds. A G-quadruplex containing a single guanine analog substitution, such as 8-oxoguanine (O) or xanthine (X), would suffer from a loss of a Hoogsteen hydrogen bond within a G-tetrad and/or potential steric hindrance. We show that a proper arrangement of O and X bases can reestablish the hydrogen-bond pattern within a G·G·X·O tetrad. Rational incorporation of G·G·X·O tetrads in a (3+1) G-quadruplex demonstrated a similar folding topology and thermal stability to that of the unmodified G-quadruplex. pH titration conducted on X·O-modified G-quadruplexes indicated a protonation-deprotonation equilibrium of X with a pKa ∼6.7. The solution structure of a G-quadruplex containing a G·G·X·O tetrad was determined, displaying the same folding topology in both the protonated and deprotonated states. A G-quadruplex containing a deprotonated X·O pair was shown to exhibit a more electronegative groove compared to that of the unmodified one. These differences are likely to manifest in the electronic properties of G-quadruplexes and may have important implications for drug targeting and DNA-protein interactions.
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Affiliation(s)
- Vee Vee Cheong
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore
| | - Brahim Heddi
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore
| | - Christopher Jacques Lech
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore
| | - Anh Tuân Phan
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore
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33
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Fleming A, Zhou J, Wallace SS, Burrows CJ. A Role for the Fifth G-Track in G-Quadruplex Forming Oncogene Promoter Sequences during Oxidative Stress: Do These "Spare Tires" Have an Evolved Function? ACS CENTRAL SCIENCE 2015; 1:226-233. [PMID: 26405692 PMCID: PMC4571166 DOI: 10.1021/acscentsci.5b00202] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Indexed: 05/24/2023]
Abstract
Uncontrolled inflammation or oxidative stress generates electron-deficient species that oxidize the genome increasing its instability in cancer. The G-quadruplex (G4) sequences regulating the c-MYC, KRAS, VEGF, BCL-2, HIF-1α, and RET oncogenes, as examples, are targets for oxidation at loop and 5'-core guanines (G) as showcased in this study by CO3•- oxidation of the VEGF G4. Products observed include 8-oxo-7,8-dihydroguanine (OG), spiroiminodihydantoin (Sp), and 5-guanidinohydantoin (Gh). Our previous studies found that OG and Gh, when present in the four G-tracks of the solved structure for VEGF and c-MYC, were not substrates for the base excision repair (BER) DNA glycosylases in biologically relevant KCl solutions. We now hypothesize that a fifth G-track found a few nucleotides distant from the G4 tracks involved in folding can act as a "spare tire," facilitating extrusion of a damaged G-run into a large loop that then becomes a substrate for BER. Thermodynamic, spectroscopic, and DMS footprinting studies verified the fifth domain replacing a damaged G-track with OG or Gh at a loop or core position in the VEGF G4. These new "spare tire"-containing strands with Gh in loops are now found to be substrates for initiation of BER with the NEIL1, NEIL2, and NEIL3 DNA glycosylases. The results support a hypothesis in which regulatory G4s carry a "spare-tire" fifth G-track for aiding in the repair process when these sequences are damaged by radical oxygen species, a feature observed in a large number of these sequences. Furthermore, formation and repair of oxidized bases in promoter regions may constitute an additional example of epigenetic modification, in this case of guanine bases, to regulate gene expression in which the G4 sequences act as sensors of oxidative stress.
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Affiliation(s)
- Aaron
M. Fleming
- Department
of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Jia Zhou
- Department
of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont 05045, United States
| | - Susan S. Wallace
- Department
of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont 05045, United States
| | - Cynthia J. Burrows
- Department
of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
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Zhou J, Fleming AM, Averill AM, Burrows CJ, Wallace SS. The NEIL glycosylases remove oxidized guanine lesions from telomeric and promoter quadruplex DNA structures. Nucleic Acids Res 2015; 43:4039-54. [PMID: 25813041 PMCID: PMC4417164 DOI: 10.1093/nar/gkv252] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 03/11/2015] [Indexed: 12/31/2022] Open
Abstract
G-quadruplex is a four-stranded G-rich DNA structure that is highly susceptible to oxidation. Despite the important roles that G-quadruplexes play in telomere biology and gene transcription, neither the impact of guanine lesions on the stability of quadruplexes nor their repair are well understood. Here, we show that the oxidized guanine lesions 8-oxo-7,8-dihydroguanine (8-oxoG), guanidinohydantoin (Gh) and spiroiminodihydantoin (Sp) reduce the thermostability and alter the folding of telomeric quadruplexes in a location-dependent manner. Also, the NEIL1 and NEIL3 DNA glycosylases can remove hydantoin lesions but none of the glycosylases, including OGG1, are able to remove 8-oxoG from telomeric quadruplexes. Interestingly, a hydantoin lesion at the site most prone to oxidation in quadruplex DNA is not efficiently removed by NEIL1 or NEIL3. However, NEIL1, NEIL2 and NEIL3 remove hydantoins from telomeric quadruplexes formed by five TTAGGG repeats much more rapidly than the commonly studied four-repeat quadruplex structures. We also show that APE1 cleaves furan in selected positions in Na+-coordinated telomeric quadruplexes. In promoter G-quadruplex DNA, the NEIL glycosylases primarily remove Gh from Na+-coordinated antiparallel quadruplexes but not K+-coordinated parallel quadruplexes containing VEGF or c-MYC promoter sequences. Thus, the NEIL DNA glycosylases may be involved in both telomere maintenance and in gene regulation.
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Affiliation(s)
- Jia Zhou
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, VT 05405, USA
| | - Aaron M Fleming
- Department of Chemistry, University of Utah, Salt Lake City, UT 84112, USA
| | - April M Averill
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, VT 05405, USA
| | - Cynthia J Burrows
- Department of Chemistry, University of Utah, Salt Lake City, UT 84112, USA
| | - Susan S Wallace
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, VT 05405, USA
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An N, Fleming AM, White HS, Burrows CJ. Nanopore detection of 8-oxoguanine in the human telomere repeat sequence. ACS NANO 2015; 9:4296-307. [PMID: 25768204 PMCID: PMC4790916 DOI: 10.1021/acsnano.5b00722] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2015] [Accepted: 03/13/2015] [Indexed: 05/23/2023]
Abstract
The human telomere repeat sequence 5'-TTAGGG-3' is a hot spot for oxidation at guanine, yielding 8-oxo-7,8-dihydroguanine (OG), a biomarker of oxidative stress. Telomere shortening resulting from oxidation will ultimately induce cellular senescence. In this study, α-hemolysin (α-HL) nanopore technology was applied to detect and quantify OG in the human telomeric DNA sequence. This repeat sequence adopts a basket G-quadruplex in the NaCl electrolyte used for analysis that enters the α-HL channel, slowly unfolds, and translocates. The basket fold containing OG disrupts the structure, leading to >10× increase in the unfolding kinetics without yielding a detectable current pattern. Therefore, detection of OG with α-HL required labeling of OG with aminomethyl-[18-crown-6] using a mild oxidant. The labeled OG yielded a pulse-like signal in the current vs time trace when the DNA strand was electrophoretically passed through α-HL in NaCl electrolyte. However, the rate of translocation was too slow using NaCl salts, leading us to further refine the method. A mixture of NH4Cl and LiCl electrolytes induced the propeller fold that unravels quickly outside the α-HL channel. This electrolyte allowed observation of the labeled OG, while providing a faster recording of the currents. Lastly, OG distributions were probed with this method in a 120-mer stretch of the human telomere sequence exposed to the cellular oxidant (1)O2. Single-molecule profiles determined the OG distributions to be random in this context. Application of the method in nanomedicine can potentially address many questions surrounding oxidative stress and telomere attrition observed in various disease phenotypes including prostate cancer and diabetes.
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Li Z, Lech CJ, Phan AT. Sugar-modified G-quadruplexes: effects of LNA-, 2'F-RNA- and 2'F-ANA-guanosine chemistries on G-quadruplex structure and stability. Nucleic Acids Res 2013; 42:4068-79. [PMID: 24371274 PMCID: PMC3973314 DOI: 10.1093/nar/gkt1312] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
G-quadruplex-forming oligonucleotides containing modified nucleotide chemistries have demonstrated promising pharmaceutical potential. In this work, we systematically investigate the effects of sugar-modified guanosines on the structure and stability of a (4+0) parallel and a (3+1) hybrid G-quadruplex using over 60 modified sequences containing a single-position substitution of 2′-O-4′-C-methylene-guanosine (LNAG), 2′-deoxy-2′-fluoro-riboguanosine (FG) or 2′-deoxy-2′-fluoro-arabinoguanosine (FANAG). Our results are summarized in two parts: (I) Generally, LNAG substitutions into ‘anti’ position guanines within a guanine-tetrad lead to a more stable G-quadruplex, while substitutions into ‘syn’ positions disrupt the native G-quadruplex conformation. However, some interesting exceptions to this trend are observed. We discover that a LNAG modification upstream of a short propeller loop hinders G-quadruplex formation. (II) A single substitution of either FG or FANAG into a ‘syn’ position is powerful enough to perturb the (3+1) G-quadruplex. Substitution of either FG or FANAG into any ‘anti’ position is well tolerated in the two G-quadruplex scaffolds. FANAG substitutions to ‘anti’ positions are better tolerated than their FG counterparts. In both scaffolds, FANAG substitutions to the central tetrad layer are observed to be the most stabilizing. The observations reported herein on the effects of LNAG, FG and FANAG modifications on G-quadruplex structure and stability will enable the future design of pharmaceutically relevant oligonucleotides.
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Affiliation(s)
- Zhe Li
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371
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37
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Vummidi BR, Alzeer J, Luedtke NW. Fluorescent Probes for G-Quadruplex Structures. Chembiochem 2013; 14:540-58. [DOI: 10.1002/cbic.201200612] [Citation(s) in RCA: 197] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Indexed: 12/19/2022]
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Doluca O, Withers JM, Filichev VV. Molecular engineering of guanine-rich sequences: Z-DNA, DNA triplexes, and G-quadruplexes. Chem Rev 2013; 113:3044-83. [PMID: 23391174 DOI: 10.1021/cr300225q] [Citation(s) in RCA: 135] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Osman Doluca
- Institute of Fundamental Sciences, Massey University, Private Bag 11 222, Palmerston North, New Zealand
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39
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Lech CJ, Phan AT. 47 Incorporation of alternative nucleic acid chemistries into G-quadruplex structure. J Biomol Struct Dyn 2013. [DOI: 10.1080/07391102.2013.786480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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40
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Structural probes in quadruplex nucleic acid structure determination by NMR. Molecules 2012; 17:13073-86. [PMID: 23128087 PMCID: PMC6268857 DOI: 10.3390/molecules171113073] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 11/01/2012] [Accepted: 11/01/2012] [Indexed: 12/31/2022] Open
Abstract
Traditionally, isotope-labelled DNA and RNA have been fundamental to nucleic acid structural studies by NMR. Four-stranded nucleic acid architectures studies increasingly benefit from a plethora of nucleotide conjugates for resonance assignments, the identification of hydrogen bond alignments, and improving the population of preferred species within equilibria. In this paper, we review their use for these purposes. Most importantly we identify reasons for the failure of some modifications to result in quadruplex formation.
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41
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Lech CJ, Li Z, Heddi B, Phan AT. 2'-F-ANA-guanosine and 2'-F-guanosine as powerful tools for structural manipulation of G-quadruplexes. Chem Commun (Camb) 2012; 48:11425-7. [PMID: 23086183 DOI: 10.1039/c2cc35097a] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Here we demonstrate the applicability of 2'-F-ANA-guanosine and 2'-F-guanosine as powerful tools for manipulating G-quadruplex folding by anti-position-favoring substitutions. A single guanine to 2'-F-ANA-guanine substitution can favor a single (3+1) hybrid conformation from a mixture of conformers. Rational substitutions of either type of 2'-F-modified nucleotide enable conformational switching from a (3+1) hybrid to a parallel folding topology.
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G-ruption: the third international meeting on G-quadruplex and G-assembly. Biochimie 2012; 94:2475-83. [PMID: 22974982 DOI: 10.1016/j.biochi.2012.09.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Accepted: 09/04/2012] [Indexed: 12/31/2022]
Abstract
A three and a half day conference focusing on nucleic acid structures called G-quadruplexes (G4s) and other guanine-based assemblies was held in Sorrento, Italy (June 28-July 1, 2011) and featured 35 invited talks and over 89 posters. The G-quadruplex field continues to expand at an explosive rate with the emergence of new connections to biology, chemistry, physics, and nanotechnology. Following the trend established by the previous two international G4 meetings, the conference touched upon all these areas and facilitated productive exchanges of ideas between researchers from all over the world.
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Dolinnaya NG, Yuminova AV, Spiridonova VA, Arutyunyan AM, Kopylov AM. Coexistence of G-quadruplex and duplex domains within the secondary structure of 31-mer DNA thrombin-binding aptamer. J Biomol Struct Dyn 2012; 30:524-31. [PMID: 22734515 DOI: 10.1080/07391102.2012.687518] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
A number of thrombin-binding DNA aptamers have been developed during recent years. So far the structure of just a single one, 15-mer thrombin-binding aptamer (15TBA), has been solved as G-quadruplex. Structures of others, showing variable anticoagulation activities, are still not known yet. In this paper, we applied the circular dichroism and UV spectroscopy to characterize the temperature unfolding and conformational features of 31-mer thrombin-binding aptamer (31TBA), whose sequence has a potential to form G-quadruplex and duplex domains. Both structural domains were monitored independently in 31TBA and in several control oligonucleotides unable to form either the duplex region or the G-quadruplex region. The major findings are as follows: (1) both duplex and G-quadruplex domains coexist in intramolecular structure of 31TBA, (2) the formation of duplex domain does not change the fold of G-quadruplex, which is very similar to that of 15TBA, and (3) the whole 31TBA structure disrupts if either of two domains is not formed: the absence of duplex structure in 31TBA abolishes G-quadruplex, and vice versa, the lack of G-quadruplex folding results in disallowing the duplex domain.
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Affiliation(s)
- N G Dolinnaya
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia
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44
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Adrian M, Heddi B, Phan AT. NMR spectroscopy of G-quadruplexes. Methods 2012; 57:11-24. [DOI: 10.1016/j.ymeth.2012.05.003] [Citation(s) in RCA: 184] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Revised: 05/15/2012] [Accepted: 05/16/2012] [Indexed: 12/24/2022] Open
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