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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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Bansal A, Phogat P, Kukreti S. A novel G·G·T non-conventional intramolecular triplex formed by the double repeat sequence of Chlamydomonas telomeric DNA. RSC Adv 2022; 12:15918-15924. [PMID: 35733691 PMCID: PMC9134377 DOI: 10.1039/d2ra00861k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 04/08/2022] [Indexed: 11/21/2022] Open
Abstract
The competition among the DNA non-canonical structures has been widely studied in repetitive DNA sequences. The Chlamydomonas reinhardtii telomere (TTTTAGGG)n is found an exception to the general idea of forming folded G-quadruplex by few repeats of any telomeric sequence.
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Affiliation(s)
- Aparna Bansal
- Nucleic Acids Research Lab, Department of Chemistry, University of Delhi (North Campus), Delhi, 110007, India
- Department of Chemistry, Hansraj College, University of Delhi, (North Campus), Delhi, 110007, India
| | - Priyanka Phogat
- Nucleic Acids Research Lab, Department of Chemistry, University of Delhi (North Campus), Delhi, 110007, India
| | - Shrikant Kukreti
- Nucleic Acids Research Lab, Department of Chemistry, University of Delhi (North Campus), Delhi, 110007, India
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3
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Molnár OR, Végh A, Somkuti J, Smeller L. Characterization of a G-quadruplex from hepatitis B virus and its stabilization by binding TMPyP4, BRACO19 and PhenDC3. Sci Rep 2021; 11:23243. [PMID: 34853392 PMCID: PMC8636512 DOI: 10.1038/s41598-021-02689-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Accepted: 11/12/2021] [Indexed: 12/22/2022] Open
Abstract
Specific guanine rich nucleic acid sequences can form non-canonical structures, like the four stranded G-quadruplex (GQ). We studied the GQ-forming sequence (named HepB) found in the genome of the hepatitis B virus. Fluorescence-, infrared- and CD-spectroscopy were used. HepB shows a hybrid form in presence of K+, but Na+, Li+, and Rb+ induce parallel structure. Higher concentrations of metal ions increase the unfolding temperature, which was explained by a short thermodynamic calculation. Temperature stability of the GQ structure was determined for all these ions. Na+ has stronger stabilizing effect on HepB than K+, which is highly unusual. The transition temperatures were 56.6, 53.8, 58.5 and 54.4 °C for Na+, K+, Li+, and Rb+ respectively. Binding constants for Na+ and K+ were 10.2 mM and 7.1 mM respectively. Study of three ligands designed in cancer research for GQ targeting (TMPyP4, BRACO19 and PhenDC3) showed unequivocally their binding to HepB. Binding was proven by the increased stability of the bound form. The stabilization was higher than 20 °C for TMPyP4 and PhenDC3, while it was considerably lower for BRACO19. These results might have medical importance in the fight against the hepatitis B virus.
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Affiliation(s)
- Orsolya Réka Molnár
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, 1094, Hungary
| | - András Végh
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, 1094, Hungary.,Department of Ophthalmology, Semmelweis University, Budapest, 1085, Hungary
| | - Judit Somkuti
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, 1094, Hungary
| | - László Smeller
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, 1094, Hungary.
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Matsumoto S, Sugimoto N. New Insights into the Functions of Nucleic Acids Controlled by Cellular Microenvironments. Top Curr Chem (Cham) 2021; 379:17. [PMID: 33782792 DOI: 10.1007/s41061-021-00329-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 03/11/2021] [Indexed: 12/11/2022]
Abstract
The right-handed double-helical B-form structure (B-form duplex) has been widely recognized as the canonical structure of nucleic acids since it was first proposed by James Watson and Francis Crick in 1953. This B-form duplex model has a monochronic and static structure and codes genetic information within a sequence. Interestingly, DNA and RNA can form various non-canonical structures, such as hairpin loops, left-handed helices, triplexes, tetraplexes of G-quadruplex and i-motif, and branched junctions, in addition to the canonical structure. The formation of non-canonical structures depends not only on sequence but also on the surrounding environment. Importantly, these non-canonical structures may exhibit a wide variety of biological roles by changing their structures and stabilities in response to the surrounding environments, which undergo vast changes at specific locations and at specific times in cells. Here, we review recent progress regarding the interesting behaviors and functions of nucleic acids controlled by molecularly crowded cellular conditions. New insights gained from recent studies suggest that nucleic acids not only code genetic information in sequences but also have unknown functions regarding their structures and stabilities through drastic structural changes in cellular environments.
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Affiliation(s)
- Saki Matsumoto
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, 7-1-20 Minatojima-Minamimachi, Kobe, 650-0047, Japan
| | - Naoki Sugimoto
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, 7-1-20 Minatojima-Minamimachi, Kobe, 650-0047, Japan. .,Graduate School of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, 7-1-20 Minatojima-Minamimachi, Kobe, 650-0047, Japan.
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5
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Chalikian TV, Liu L, Macgregor RB. Duplex-tetraplex equilibria in guanine- and cytosine-rich DNA. Biophys Chem 2020; 267:106473. [PMID: 33031980 DOI: 10.1016/j.bpc.2020.106473] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 09/03/2020] [Indexed: 02/07/2023]
Abstract
Noncanonical four-stranded DNA structures, including G-quadruplexes and i-motifs, have been discovered in the cell and are implicated in a variety of genomic regulatory functions. The tendency of a specific guanine- and cytosine-rich region of genomic DNA to adopt a four-stranded conformation depends on its ability to overcome the constraints of duplex base-pairing by undergoing consecutive duplex-to-coil and coil-to-tetraplex transitions. The latter ability is determined by the balance between the free energies of participating ordered and disordered structures. In this review, we present an overview of the literature on the stability of G-quadruplex and i-motif structures and discuss the extent of duplex-tetraplex competition as a function of the sequence context of the DNA and environmental conditions including temperature, pH, salt, molecular crowding, and the presence of G-quadruplex-binding ligands. We outline how the results of in vitro studies can be expanded to understanding duplex-tetraplex equilibria in vivo.
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Affiliation(s)
- Tigran V Chalikian
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada.
| | - Lutan Liu
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
| | - Robert B Macgregor
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
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6
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Chasing Particularities of Guanine- and Cytosine-Rich DNA Strands. Molecules 2020; 25:molecules25030434. [PMID: 31972988 PMCID: PMC7037129 DOI: 10.3390/molecules25030434] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 01/17/2020] [Accepted: 01/20/2020] [Indexed: 01/17/2023] Open
Abstract
By substitution of natural nucleotides by their abasic analogs (i.e., 1',2'-dideoxyribose phosphate residue) at critically chosen positions within 27-bp DNA constructs originating from the first intron of N-myc gene, we hindered hybridization within the guanine- and cytosine-rich central region and followed formation of non-canonical structures. The impeded hybridization between the complementary strands leads to time-dependent structural transformations of guanine-rich strand that are herein characterized with the use of solution-state NMR, CD spectroscopy, and native polyacrylamide gel electrophoresis. Moreover, the DNA structural changes involve transformation of intra- into inter-molecular G-quadruplex structures that are thermodynamically favored. Intriguingly, the transition occurs in the presence of complementary cytosine-rich strands highlighting the inability of Watson-Crick base-pairing to preclude the transformation between G-quadruplex structures that occurs via intertwining mechanism and corroborates a role of G-quadruplex structures in DNA recombination processes.
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Bošković F, Zhu J, Chen K, Keyser UF. Monitoring G-Quadruplex Formation with DNA Carriers and Solid-State Nanopores. NANO LETTERS 2019; 19:7996-8001. [PMID: 31577148 DOI: 10.1021/acs.nanolett.9b03184] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
G-quadruplexes (Gqs) are guanine-rich DNA structures formed by single-stranded DNA. They are of paramount significance to gene expression regulation, but also drug targets for cancer and human viruses. Current ensemble and single-molecule methods require fluorescent labels, which can affect Gq folding kinetics. Here we introduce, a single-molecule Gq nanopore assay (smGNA) to detect Gqs and kinetics of Gq formation. We use ∼5 nm solid-state nanopores to detect various Gq structural variants attached to designed DNA carriers. Gqs can be identified by localizing their positions along designed DNA carriers, establishing smGNA as a tool for Gq mapping. In addition, smGNA allows for discrimination of (un)folded Gq structures, provides insights into single-molecule kinetics of Gq folding, and probes quadruplex-to-duplex structural transitions. smGNA can elucidate the formation of Gqs at the single-molecule level without labeling and has potential implications on the study of these structures both in single-stranded DNA and in genomic samples.
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Affiliation(s)
- Filip Bošković
- Cavendish Laboratory , University of Cambridge , JJ Thompson Avenue , Cambridge CB3 0HE , United Kingdom
| | - Jinbo Zhu
- Cavendish Laboratory , University of Cambridge , JJ Thompson Avenue , Cambridge CB3 0HE , United Kingdom
| | - Kaikai Chen
- Cavendish Laboratory , University of Cambridge , JJ Thompson Avenue , Cambridge CB3 0HE , United Kingdom
| | - Ulrich F Keyser
- Cavendish Laboratory , University of Cambridge , JJ Thompson Avenue , Cambridge CB3 0HE , United Kingdom
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8
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Paul S, Hossain SS, M BD, Samanta A. Interactions between a Bioflavonoid and c-MYC Promoter G-Quadruplex DNA: Ensemble and Single-Molecule Investigations. J Phys Chem B 2019; 123:2022-2031. [DOI: 10.1021/acs.jpcb.9b00335] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Sneha Paul
- School of Chemistry, University of Hyderabad, Hyderabad 500046, India
| | - Sk Saddam Hossain
- School of Chemistry, University of Hyderabad, Hyderabad 500046, India
| | - Bala Divya M
- School of Chemistry, University of Hyderabad, Hyderabad 500046, India
| | - Anunay Samanta
- School of Chemistry, University of Hyderabad, Hyderabad 500046, India
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9
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Kaulage MH, Bhattacharya S, Muniyappa K. Structural Characterization of i-Motif Structure in the Human Acetyl-CoA Carboxylase 1 Gene Promoters and Their Role in the Regulation of Gene Expression. Chembiochem 2018; 19:1078-1087. [DOI: 10.1002/cbic.201800021] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Indexed: 12/26/2022]
Affiliation(s)
- Mangesh H. Kaulage
- Department of Biochemistry; Indian Institute of Science; Bengaluru 560012 India
- Department of Organic Chemistry; Indian Institute of Science; Bengaluru 560012 India
| | - Santanu Bhattacharya
- Department of Organic Chemistry; Indian Institute of Science; Bengaluru 560012 India
| | - K. Muniyappa
- Department of Biochemistry; Indian Institute of Science; Bengaluru 560012 India
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10
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Alkyne-substituted diminazene as G-quadruplex binders with anticancer activities. Eur J Med Chem 2016; 118:266-75. [DOI: 10.1016/j.ejmech.2016.04.030] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 04/11/2016] [Accepted: 04/11/2016] [Indexed: 01/18/2023]
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11
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Wang SK, Su HF, Gu YC, Lin SL, Tan JH, Huang ZS, Ou TM. Complicated behavior of G-quadruplexes and evaluating G-quadruplexes' ligands in various systems mimicking cellular circumstance. Biochem Biophys Rep 2015; 5:439-447. [PMID: 28955851 PMCID: PMC5600415 DOI: 10.1016/j.bbrep.2015.09.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2015] [Revised: 09/23/2015] [Accepted: 09/25/2015] [Indexed: 01/09/2023] Open
Abstract
Environments surrounding G-rich sequences remarkably affect the conformations of these structures. A proper evaluation system mimicking the crowded environment in a cell with macromolecules should be developed to perform structural and functional studies on G-quadruplexes. In this study, the topology and stability of a G-quadruplex formed by human telomeric repeat sequences were investigated in a macromolecule-crowded environment created by polyethylene glycol 200 (PEG200), tumor cell extract, and Xenopus laevis egg extract. The interactions between small molecules and telomeric G-quadruplexes were also evaluated in the different systems. The results suggested that the actual behavior of G-quadruplex structures in cells extract is quite different from that in the PEG crowding system, and proteins or other factors in extracts might play a very important role in G-quadruplex structures. Cell-free system was constructed using HL60 cell extract. Topologies and stability of G-quadruplexes were identified in different systems. G-quadruplex’s ligands’ effects were evaluated in different systems.
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Affiliation(s)
- Shi-Ke Wang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Hua-Fei Su
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Yu-Chao Gu
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Shu-Ling Lin
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Jia-Heng Tan
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Zhi-Shu Huang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Tian-Miao Ou
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
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12
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Verdian Doghaei A, Housaindokht M, Bozorgmehr M. Molecular crowding effects on conformation and stability of G-quadruplex DNA structure: Insights from molecular dynamics simulation. J Theor Biol 2015; 364:103-12. [DOI: 10.1016/j.jtbi.2014.09.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 07/14/2014] [Accepted: 09/10/2014] [Indexed: 11/25/2022]
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13
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Yurenko YP, Novotný J, Sklenář V, Marek R. Exploring non-covalent interactions in guanine- and xanthine-based model DNA quadruplex structures: a comprehensive quantum chemical approach. Phys Chem Chem Phys 2014; 16:2072-84. [DOI: 10.1039/c3cp53875c] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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Sugimoto N. Noncanonical structures and their thermodynamics of DNA and RNA under molecular crowding: beyond the Watson-Crick double helix. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2014; 307:205-73. [PMID: 24380597 DOI: 10.1016/b978-0-12-800046-5.00008-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
How does molecular crowding affect the stability of nucleic acid structures inside cells? Water is the major solvent component in living cells, and the properties of water in the highly crowded media inside cells differ from that in buffered solution. As it is difficult to measure the thermodynamic behavior of nucleic acids in cells directly and quantitatively, we recently developed a cell-mimicking system using cosolutes as crowding reagents. The influences of molecular crowding on the structures and thermodynamics of various nucleic acid sequences have been reported. In this chapter, we discuss how the structures and thermodynamic properties of nucleic acids differ under various conditions such as highly crowded environments, compartment environments, and in the presence of ionic liquids, and the major determinants of the crowding effects on nucleic acids are discussed. The effects of molecular crowding on the activities of ribozymes and riboswitches on noncanonical structures of DNA- and RNA-like quadruplexes that play important roles in transcription and translation are also described.
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Affiliation(s)
- Naoki Sugimoto
- Frontier Institute for Biomolecular Engineering Research (FIBER) and Faculty of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, Kobe, Japan.
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15
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Amato J, Stellato MI, Pizzo E, Petraccone L, Oliviero G, Borbone N, Piccialli G, Orecchia A, Bellei B, Castiglia D, Giancola C. PNA as a potential modulator of COL7A1 gene expression in dominant dystrophic epidermolysis bullosa: a physico-chemical study. MOLECULAR BIOSYSTEMS 2013; 9:3166-74. [PMID: 24121392 DOI: 10.1039/c3mb70283a] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Dominant diseases are single gene disorders occurring in the heterozygous state. The mutated allele exerts a dominant effect because it produces an abnormal polypeptide that interferes with the function of the normal allele product. Peptide Nucleic Acids (PNAs) offer a route for a potential therapy for dominant diseases by selectively silencing the allele carrying the dominant mutation. Here, we have synthesized and studied the properties of a 15-mer PNA fully complementary to the site of the c.5272-38T>A sequence variation, which identifies a recurrent mutant COL7A1 allele causing dominant dystrophic epidermolysis bullosa (DDEB), a mendelian disease characterized by skin blistering. The PNA was conjugated with four lysine residues at the C-terminus and a fluorescent probe at the N-terminus. Physico-chemical results proved the formation of a stable, selective PNA/mutant-DNA heteroduplex in vitro. Intriguingly, when transfected into normal human fibroblasts, the PNA correctly localized in the cell nucleus. Our results open new therapeutic possibilities for patients with DDEB.
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Affiliation(s)
- Jussara Amato
- Department of Pharmacy, University of Naples "Federico II", via D. Montesano 49, 80131 Naples, Italy.
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Le VH, Nagesh N, Lewis EA. Bcl-2 promoter sequence G-quadruplex interactions with three planar and non-planar cationic porphyrins: TMPyP4, TMPyP3, and TMPyP2. PLoS One 2013; 8:e72462. [PMID: 23977303 PMCID: PMC3748076 DOI: 10.1371/journal.pone.0072462] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Accepted: 07/18/2013] [Indexed: 12/31/2022] Open
Abstract
The interactions of three related cationic porphyrins, TMPyP4, TMPyP3 and TMPyP2, with a WT 39-mer Bcl-2 promoter sequence G-quadruplex were studied using Circular Dichroism, ESI mass spectrometry, Isothermal Titration Calorimetry, and Fluorescence spectroscopy. The planar cationic porphyrin TMPyP4 (5, 10, 15, 20-meso-tetra (N-methyl-4-pyridyl) porphine) is shown to bind to a WT Bcl-2 G-quadruplex via two different binding modes, an end binding mode and a weaker mode attributed to intercalation. The related non-planar ligands, TMPyP3 and TMPyP2, are shown to bind to the Bcl-2 G-quadruplex by a single mode. ESI mass spectrometry experiments confirmed that the saturation stoichiometry is 4:1 for the TMPyP4 complex and 2:1 for the TMPyP2 and TMPyP3 complexes. ITC experiments determined that the equilibrium constant for formation of the (TMPyP4)1/DNA complex (K1 = 3.7 × 10(6)) is approximately two orders of magnitude greater than the equilibrium constant for the formation of the (TMPyP2)1/DNA complex, (K1 = 7.0 × 10(4)). Porphyrin fluorescence is consistent with intercalation in the case of the (TMPyP4)3/DNA and (TMPyP4)4/DNA complexes. The non-planar shape of the TMPyP2 and TMPyP3 molecules results in both a reduced affinity for the end binding interaction and the elimination of the intercalation binding mode.
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Affiliation(s)
- Vu H. Le
- Department of Chemistry, Mississippi State University, Mississippi State, Mississippi, United States of America
| | - Narayana Nagesh
- Centre for Cellular and Molecular Biology, Hyderabad, Andhra Pradesh, India
| | - Edwin A. Lewis
- Department of Chemistry, Mississippi State University, Mississippi State, Mississippi, United States of America
- * E-mail:
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17
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König SLB, Huppert JL, Sigel RKO, Evans AC. Distance-dependent duplex DNA destabilization proximal to G-quadruplex/i-motif sequences. Nucleic Acids Res 2013; 41:7453-61. [PMID: 23771141 PMCID: PMC3753619 DOI: 10.1093/nar/gkt476] [Citation(s) in RCA: 28] [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: 10/11/2012] [Revised: 05/04/2013] [Accepted: 05/08/2013] [Indexed: 01/29/2023] Open
Abstract
G-quadruplexes and i-motifs are complementary examples of non-canonical nucleic acid substructure conformations. G-quadruplex thermodynamic stability has been extensively studied for a variety of base sequences, but the degree of duplex destabilization that adjacent quadruplex structure formation can cause has yet to be fully addressed. Stable in vivo formation of these alternative nucleic acid structures is likely to be highly dependent on whether sufficient spacing exists between neighbouring duplex- and quadruplex-/i-motif-forming regions to accommodate quadruplexes or i-motifs without disrupting duplex stability. Prediction of putative G-quadruplex-forming regions is likely to be assisted by further understanding of what distance (number of base pairs) is required for duplexes to remain stable as quadruplexes or i-motifs form. Using oligonucleotide constructs derived from precedented G-quadruplexes and i-motif-forming bcl-2 P1 promoter region, initial biophysical stability studies indicate that the formation of G-quadruplex and i-motif conformations do destabilize proximal duplex regions. The undermining effect that quadruplex formation can have on duplex stability is mitigated with increased distance from the duplex region: a spacing of five base pairs or more is sufficient to maintain duplex stability proximal to predicted quadruplex/i-motif-forming regions.
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Affiliation(s)
- Sebastian L. B. König
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK, Institute of Inorganic Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland and University of Nice-Sophia Antipolis, UMR 7272 CNRS, Institut de 40 Chimie de Nice, 28 Avenue Valrose, 06108 Nice, France
| | - Julian L. Huppert
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK, Institute of Inorganic Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland and University of Nice-Sophia Antipolis, UMR 7272 CNRS, Institut de 40 Chimie de Nice, 28 Avenue Valrose, 06108 Nice, France
| | - Roland K. O. Sigel
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK, Institute of Inorganic Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland and University of Nice-Sophia Antipolis, UMR 7272 CNRS, Institut de 40 Chimie de Nice, 28 Avenue Valrose, 06108 Nice, France
| | - Amanda C. Evans
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK, Institute of Inorganic Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland and University of Nice-Sophia Antipolis, UMR 7272 CNRS, Institut de 40 Chimie de Nice, 28 Avenue Valrose, 06108 Nice, France
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18
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Miyoshi D, Fujimoto T, Sugimoto N. Molecular Crowding and Hydration Regulating of G-Quadruplex Formation. Top Curr Chem (Cham) 2012; 330:87-110. [DOI: 10.1007/128_2012_335] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Pramanik S, Nagatoishi S, Sugimoto N. DNA tetraplex structure formation from human telomeric repeat motif (TTAGGG):(CCCTAA) in nanocavity water pools of reverse micelles. Chem Commun (Camb) 2012; 48:4815-7. [PMID: 22456442 DOI: 10.1039/c2cc30622k] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In an equimolar ratio the human telomeric oligonucleotides d[AGGG(TTAGGG)(3)] and d[(CCCTAA)(3)CCCT] formed mixed structures of duplex and tetraplex in bis(2-ethylhexyl)sulfosuccinate reverse micelles; only the duplex was observed in aqueous buffer. This finding suggests that heterogeneous confined media in the cell nucleus might induce a significant fraction of the telomeric region of genomic DNA to adopt non-canonical tetraplex structure.
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Affiliation(s)
- Smritimoy Pramanik
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, 7-1-20 Minatojima-minamimachi, Kobe 650-0047, Japan
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Petraccone L, Pagano B, Giancola C. Studying the effect of crowding and dehydration on DNA G-quadruplexes. Methods 2012; 57:76-83. [PMID: 22406490 DOI: 10.1016/j.ymeth.2012.02.011] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Revised: 02/20/2012] [Accepted: 02/21/2012] [Indexed: 01/01/2023] Open
Abstract
Intracellular environment is crowded with biomolecules that occupy a significant fraction (up to 40%) of the cellular volume, with a total concentration in the range 300-400mg/ml. Recently, the effect of crowding/dehydrating agents on the DNA G-quadruplexes has become a subject of an increasing interest. Crowding and/or dehydrating agents have been used to simulate how G-quadruplexes behave under cell-mimicking conditions characterized by a large excluded volume and a lower water activity. Indeed, the presence of both steric crowding and a lower water activity can affect G-quadruplex stability, their folding/unfolding kinetics, as well as their binding processes with proteins or small ligands. Many of these effects can be explored experimentally by measuring the dependence of the conformational stability, isomerisation kinetics and equilibria on the concentration of cosolutes which do not interact with the molecules (G-quadruplexes) under investigation. Spectroscopic methodologies, like circular dichroism, UV and fluorescence, have been widely employed to study G-quadruplexes in dilute solution. Here we focus on some aspects that need to be taken into account when employing such techniques in the presence of large amount of a cosolute. Additionally, we discuss possible problems/artifacts that arise in setting experiments in presence of these commonly employed cosolutes and in interpreting the results.
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Affiliation(s)
- Luigi Petraccone
- Dipartimento di Scienze Chimiche, Università degli Studi di Napoli "Federico II", Via Cintia, I-80126 Napoli, Italy
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Juskowiak B, Paczesny J. The interaction between G-quadruplex-forming oligonucleotide and cationic surfactant monolayer at the air/water interface. J Colloid Interface Sci 2011; 365:150-5. [PMID: 21963205 DOI: 10.1016/j.jcis.2011.09.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 09/07/2011] [Accepted: 09/08/2011] [Indexed: 11/30/2022]
Abstract
We report on the interactions between a 21-mer quadruplex-forming oligonucleotide bearing human telomere sequence of dG(3)(T(2)AG(3))(3) (G4 DNA) and a positively charged dioctadecyldimethylammonium bromide (DODAB) monolayer at the air-aqueous interface, studied by surface film balance measurements. In the presence of G4 DNA, the π-A isotherm of the cationic Langmuir film shifted to lower molecular areas when compared with the reference isotherm recorded on the subphase containing only 50 mM triethylamine-acetate (TEAA) buffer. The presence of quadruplex-stabilizing metal cations (K(+) or Na(+)) further affected profiles of π-A isotherms. Further insight into processes related to the G4 DNA-monolayer interactions was provided by recording time profiles of the surface pressure of monolayer at a constant mean molecular area. In these experiments G4 DNA and/or metal ions were sequentially injected under the monolayer surface. Results indicated that multistranded assemblies of G4 DNA were formed at the monolayer interface even in the absence of metal ions, which suggested that the charged cationic surface of Langmuir monolayer induced aggregation of guanine-rich DNA strands. The presence of sodium and potassium ions inhibited formation of multi-stranded assemblies through the competitive G-quadruplex formation but to different extent that might be related to the differences in stability and topology of both quadruplexes.
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Affiliation(s)
- Bernard Juskowiak
- Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznan, Poland.
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Mullen MA, Olson KJ, Dallaire P, Major F, Assmann SM, Bevilacqua PC. RNA G-Quadruplexes in the model plant species Arabidopsis thaliana: prevalence and possible functional roles. Nucleic Acids Res 2010; 38:8149-63. [PMID: 20860998 PMCID: PMC3001093 DOI: 10.1093/nar/gkq804] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 08/24/2010] [Accepted: 08/30/2010] [Indexed: 01/25/2023] Open
Abstract
Tandem stretches of guanines can associate in hydrogen-bonded arrays to form G-quadruplexes, which are stabilized by K(+) ions. Using computational methods, we searched for G-Quadruplex Sequence (GQS) patterns in the model plant species Arabidopsis thaliana. We found ∼ 1200 GQS with a G(3) repeat sequence motif, most of which are located in the intergenic region. Using a Markov modeled genome, we determined that GQS are significantly underrepresented in the genome. Additionally, we found ∼ 43,000 GQS with a G(2) repeat sequence motif; notably, 80% of these were located in genic regions, suggesting that these sequences may fold at the RNA level. Gene Ontology functional analysis revealed that GQS are overrepresented in genes encoding proteins of certain functional categories, including enzyme activity. Conversely, GQS are underrepresented in other categories of genes, notably those for non-coding RNAs such as tRNAs and rRNAs. We also find that genes that are differentially regulated by drought are significantly more likely to contain a GQS. CD-detected K(+) titrations performed on representative RNAs verified formation of quadruplexes at physiological K(+) concentrations. Overall, this study indicates that GQS are present at unique locations in Arabidopsis and that folding of RNA GQS may play important roles in regulating gene expression.
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Affiliation(s)
- Melissa A. Mullen
- Department of Chemistry, Department of Biology, The Pennsylvania State University, University Park, Pennsylvania 16802-5302, USA and Institute for Research in Immunology and Cancer (IRIC), Department of Computer Science and Operations Research, Université de Montréal, PO Box 6128, Downtown Station, Montréal, Québec H3C 3J7, Canada
| | - Kalee J. Olson
- Department of Chemistry, Department of Biology, The Pennsylvania State University, University Park, Pennsylvania 16802-5302, USA and Institute for Research in Immunology and Cancer (IRIC), Department of Computer Science and Operations Research, Université de Montréal, PO Box 6128, Downtown Station, Montréal, Québec H3C 3J7, Canada
| | - Paul Dallaire
- Department of Chemistry, Department of Biology, The Pennsylvania State University, University Park, Pennsylvania 16802-5302, USA and Institute for Research in Immunology and Cancer (IRIC), Department of Computer Science and Operations Research, Université de Montréal, PO Box 6128, Downtown Station, Montréal, Québec H3C 3J7, Canada
| | - François Major
- Department of Chemistry, Department of Biology, The Pennsylvania State University, University Park, Pennsylvania 16802-5302, USA and Institute for Research in Immunology and Cancer (IRIC), Department of Computer Science and Operations Research, Université de Montréal, PO Box 6128, Downtown Station, Montréal, Québec H3C 3J7, Canada
| | - Sarah M. Assmann
- Department of Chemistry, Department of Biology, The Pennsylvania State University, University Park, Pennsylvania 16802-5302, USA and Institute for Research in Immunology and Cancer (IRIC), Department of Computer Science and Operations Research, Université de Montréal, PO Box 6128, Downtown Station, Montréal, Québec H3C 3J7, Canada
| | - Philip C. Bevilacqua
- Department of Chemistry, Department of Biology, The Pennsylvania State University, University Park, Pennsylvania 16802-5302, USA and Institute for Research in Immunology and Cancer (IRIC), Department of Computer Science and Operations Research, Université de Montréal, PO Box 6128, Downtown Station, Montréal, Québec H3C 3J7, Canada
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Selective recognition of oncogene promoter G-quadruplexes by Mg2+. Biochem Biophys Res Commun 2010; 402:614-8. [DOI: 10.1016/j.bbrc.2010.10.065] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Accepted: 10/17/2010] [Indexed: 01/19/2023]
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Agarwal T, Roy S, Chakraborty TK, Maiti S. Selective Targeting of G-Quadruplex Using Furan-Based Cyclic Homooligopeptides: Effect on c-MYC Expression. Biochemistry 2010; 49:8388-97. [DOI: 10.1021/bi1005927] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Tani Agarwal
- Proteomics and Structural Biology Unit, Institute of Genomics and Integrative Biology, CSIR, Mall Road, New Delhi 110 007, India
| | - Saumya Roy
- Indian Institute of Chemical Technology, CSIR, Hyderabad 500 007, India
| | - Tushar Kanti Chakraborty
- Indian Institute of Chemical Technology, CSIR, Hyderabad 500 007, India
- Central Drug Research Institute, CSIR, Lucknow 226 001, India
| | - Souvik Maiti
- Proteomics and Structural Biology Unit, Institute of Genomics and Integrative Biology, CSIR, Mall Road, New Delhi 110 007, India
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Jaumot J, Gargallo R. Using principal component analysis to find correlations between loop-related and thermodynamic variables for G-quadruplex-forming sequences. Biochimie 2010; 92:1016-23. [PMID: 20452394 DOI: 10.1016/j.biochi.2010.04.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Accepted: 04/26/2010] [Indexed: 01/07/2023]
Abstract
The application of Principal Component Analysis (PCA) is proposed here as a simple means of revealing correlations between thermodynamic variables corresponding to folding equilibria of intramolecular G-quadruplexes and Watson-Crick duplexes, and the length of loops in the corresponding guanine-rich DNA sequences. To this end, two previously studied data sets were analyzed (Arora and Maiti, J. Phys. Chem. B. 2009 and Kumar and Maiti, Nucleic Acids. Res. 2008). All of the sequences considered shared the common structure 5'- GGG - loop1 - GGG - loop2 - GGG - loop3 - GGG -3'. PCA of these data sets supported a series of correlations between the variables studied. First, the association of loop length with thermodynamic stability and quadruplex structure was corroborated. Secondly, it is proposed that the addition of ethylene glycol produces a stronger stabilization on those sequences showing long loop1 and/or loop3. Thirdly, it is proposed that a low content of adenine in loop1 and/or loop3 will produce an increase in the stability of G-quadruplex and its related Watson-Crick duplex.
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Affiliation(s)
- Joaquim Jaumot
- Solution Equilibria and Chemometrics Group (Associate Unit UB-CSIC), Department of Analytical Chemistry, University of Barcelona, Barcelona, Spain
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26
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Abu-Ghazalah RM, Irizar J, Helmy AS, Macgregor RB. A study of the interactions that stabilize DNA frayed wires. Biophys Chem 2010; 147:123-9. [PMID: 20122787 DOI: 10.1016/j.bpc.2010.01.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Revised: 01/12/2010] [Accepted: 01/13/2010] [Indexed: 10/19/2022]
Abstract
Oligodeoxyribonucleotides (ODNs) with long, terminal runs of consecutive guanines, and either a dA or dT tract at the other end form higher-order structures called DNA frayed wires. These aggregates self-assemble into species consisting of 2, 3, 4, 5, ... associated strands. Some of the remarkable features of these structures are their extreme thermostability and resistance to chemical denaturants and nucleases. However, the nature of the molecular interactions that stabilize these structures remains unclear. Based on dimethyl sulfate (DMS) methylation results, our group previously proposed DNA frayed wires to be a unique set of nucleic-acid assemblies in which the N7 of guanine does not participate in the guanine-guanine interactions. To probe the hydrogen bonding involved in the stabilization of d(A(15)G(15)) frayed wires, we used Raman spectroscopy in which the DNA sample is held in photonic crystal fibers. This technique significantly enhances the signals thus allowing the use of very low laser power. Based on our results for d(A(15)G(15)) and those of incorporating the isoelectronic guanine analog pyrazolo[3,4,-d]pyrimidine or PPG, into a frayed wire-forming sequence, we provide evidence that these structures are based on the G-quadruplex model. Furthermore, from the Raman spectrum, we observed markers that are consistent with the presence of deoxyguanosine residues in the syn conformation, this suggests the presence of anti-parallel G-quadruplexes. To identify the species that contain syn guanine residues, we used circular dichroism and gel electrophoresis to study an ODN in which all of the guanine residues were brominated, d(A(15)(8-Br)G(15)). In the presence of potassium, d(A(15)(8-Br)G(15)) forms what appears to be an anti-parallel dimeric G-quadruplex. To our knowledge, this is the first report of a DNA sequence having all its guanine residues replaced by 8-bromo-guanine and maintaining its ability to form a G-quadruplex structure.
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Affiliation(s)
- Rashid M Abu-Ghazalah
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College St., Toronto, Ontario, Canada
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27
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Shi S, Zhao J, Geng X, Yao T, Huang H, Liu T, Zheng L, Li Z, Yang D, Ji L. Molecular “light switch” for G-quadruplexes and i-motif of human telomeric DNA: [Ru(phen)2(dppz)]2+. Dalton Trans 2010; 39:2490-3. [DOI: 10.1039/b916094a] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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28
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Bucek P, Jaumot J, Aviñó A, Eritja R, Gargallo R. pH-Modulated WatsonâCrick DuplexâQuadruplex Equilibria of Guanine-Rich and Cytosine-Rich DNA Sequences 140 Base Pairs Upstream of thec-kitTranscription Initiation Site. Chemistry 2009; 15:12663-71. [DOI: 10.1002/chem.200901631] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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29
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Zheng KW, Chen Z, Hao YH, Tan Z. Molecular crowding creates an essential environment for the formation of stable G-quadruplexes in long double-stranded DNA. Nucleic Acids Res 2009; 38:327-38. [PMID: 19858105 PMCID: PMC2800236 DOI: 10.1093/nar/gkp898] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Large numbers of guanine-rich sequences with potential to form G-quadruplexes have been identified in genomes of various organisms. Such sequences are constrained at both ends by long DNA duplex with a complementary strand in close proximity to compete for duplex formation. G-quadruplex/duplex competition in long double-stranded DNA has rarely been studied. In this work, we used DMS footprinting and gel electrophoresis to study G-quadruplex formation in long double-stranded DNA derived from human genome under both dilute and molecular crowding condition created by PEG. G-quadruplex formation was observed in the process of RNA transcription and after heat denaturation/renaturation under molecular crowding condition. Our results showed that the heat denaturation/renaturation treatment followed by gel electrophoresis could provide a simple method to quantitatively access the ability of G-quadruplex formation in long double-stranded DNA. The effect of K+ and PEG concentration was investigated and we found that stable G-quadruplexes could only form under the crowding condition with PEG at concentrations near the physiological concentration of biomass in living cells. This observation reveals a physical basis for the formation of stable G-quadruplexes in genome and supports its presence under the in vivo molecular crowding condition.
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Affiliation(s)
- Ke-wei Zheng
- Laboratory of Biochemistry and Biophysics, College of Life Sciences, Wuhan University, Wuhan, PR China
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30
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Zhou J, Wei C, Jia G, Wang X, Feng Z, Li C. Human telomeric G-quadruplex formed from duplex under near physiological conditions: Spectroscopic evidence and kinetics. Biochimie 2009; 91:1104-11. [DOI: 10.1016/j.biochi.2009.05.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2009] [Accepted: 05/29/2009] [Indexed: 10/20/2022]
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31
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Arora A, Maiti S. Stability and molecular recognition of quadruplexes with different loop length in the absence and presence of molecular crowding agents. J Phys Chem B 2009; 113:8784-92. [PMID: 19480441 DOI: 10.1021/jp809486g] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
G-quadruplexes are known to be potential targets for therapeutic intervention, thus resulting in development of various quadruplex interacting ligands. However, until now, no systemic study has been performed to understand molecular recognition of quadruplex in the presence of molecular crowding agents mimicking cellular conditions. The stability and molecular recognition of quadruplex can be influenced by loop length. Herein, we attempted to study the interaction of 5,10,15,20-tetrakis(1-methyl-4-pyridyl)-21H,23H-porphine (TMPyP4), a well-known G-quadruplex binding ligand with various DNA quadruplexes differing in total loop length and loop arrangement in both the absence and presence of molecular crowding agents. Results obtained from CD studies revealed that longer loops favor mixed and antiparallel conformation in both the absence and presence of 30% ethylene glycol. UV thermal melting studies revealed that the stability and formation of quadruplex increases in the presence of 30% ethylene glycol. Moreover, the binding of TMPyP4 molecule to both of the binding sites in different quadruplexes with total loop length varying from 3 to 9 remains unchanged in both the absence and presence of 30% ethylene glycol. The binding affinity (K(a)) of TMPyP4 was found to be decreased approximately by 1 order for the quadruplex sequences with total loop length varying from 11 to 15 in the presence of molecular crowding agents.
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Affiliation(s)
- Amit Arora
- Institute of Genomics and Integrative Biology, CSIR, Delhi, India
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32
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Arora A, Maiti S. Differential biophysical behavior of human telomeric RNA and DNA quadruplex. J Phys Chem B 2009; 113:10515-20. [PMID: 19572668 DOI: 10.1021/jp810638n] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Quadruplex forming potential has also been observed at the RNA level and has been associated with molecular function and recognition; however, biophysical characterization of these structures to understand their recognition properties still remains a subject of investigation. We employed CD and UV spectroscopy to understand the conformation and stability of a 24-mer human telomeric RNA quadruplex and compared it with that of the corresponding DNA analogue in 100 mM KCl containing solution. We observed that the RNA quadruplex adopts a parallel conformation and displays remarkably high thermal stabilities as compared to its DNA counterpart. Using the osmotic stress method, we determined the net release of 6.0+/-0.5 and 4.0+/-0.4 water molecules from the RNA and DNA quadruplex structure, respectively. Furthermore, UV titration experiments showed that both human telomeric RNA and DNA quadruplexes possess similar recognition abilities for TMPyP4 molecules. Our study provides a lead in extending the knowledge generated for the DNA quadruplex to the RNA level.
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Affiliation(s)
- Amit Arora
- Proteomics and Structural Biology Unit, Institute of Genomics and Integrative Biology, CSIR, Mall Road, Delhi 110 007, India
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Li H, Liu Y, Lin S, Yuan G. Spectroscopy probing of the formation, recognition, and conversion of a G-quadruplex in the promoter region of the bcl-2 oncogene. Chemistry 2009; 15:2445-52. [PMID: 19156807 DOI: 10.1002/chem.200801922] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
This study has demonstrated the formation of the G-quadruplex structure from the G-rich sequence in the promoter region of the bcl-2 oncogene; the formation could be induced by addition of NH(4)(+) or K(+) ions. The binding affinity and stoichiometry of seven small molecules with the G-quadruplex were examined by using ESI-MS, as well as CD and UV spectroscopy. The binding-affinity order was determined to be P1 approximately = P5 > P2 > P3 approximately = P4 > P7 > P6. In particular, the small-molecule induction of the structural transition between the G-quadruplex and duplex DNA forms in this promoter region was investigated by ESI-MS. We directly observed specific binding of dehydrocorydaline (P7) and cationic porphyrin (P5) in one system consisting of the G-quadruplex and the duplex DNA, respectively. The results indicate that P7 selectively stabilizes the G-quadruplex and shifts the equilibrium toward G-quadruplex formation of the bcl-2 promoter, whereas P5 converts the G-quadruplex into the duplex DNA, which results in strong and selective binding to the duplex form. Therefore, P5 and P7 with their attractive binding specificities could be considered as precursors for pathway-specific drug design for regulation of bcl-2 oncogene transcription.
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Affiliation(s)
- Huihui Li
- Beijing National Laboratory for Molecular Sciences, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
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34
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Arora A, Nair DR, Maiti S. Effect of flanking bases on quadruplex stability and Watson-Crick duplex competition. FEBS J 2009; 276:3628-40. [PMID: 19490117 DOI: 10.1111/j.1742-4658.2009.07082.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Guanine-rich DNA sequences have the ability to fold into four-stranded structures called G-quadruplexes, and are considered as promising anticancer targets. Although the G-quadruplex structure is composed of quartets and interspersed loops, in the genome it is also flanked on each side by numerous bases. The effect of loop length and composition on quadruplex conformation and stability has been well investigated in the past, but the effect of flanking bases on quadruplex stability and Watson-Crick duplex competition has not been addressed. We have studied in detail the effect of flanking bases on quadruplex stability and on duplex formation by the G-quadruplex in the presence of complementary strands using the quadruplex-forming sequence located in the promoter region of the c-kit oncogene. The results obtained from CD, thermal difference spectrum and UV melting demonstrated the effect of flanking bases on quadruplex structure and stability. With the increase in flank length, the increase in the more favorable DeltaH(vH) is accompanied by a striking increase in the unfavorable DeltaS(vH), which resulted in a decrease in the overall DeltaG(vH) of quadruplex formation. Furthermore, CD, fluorescence and isothermal titration calorimetry studies demonstrated that the propensity to attain quadruplex structure decreases with increasing flank length.
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Affiliation(s)
- Amit Arora
- Proteomics and Structural Biology Unit, Institute of Genomics and Integrative Biology, Council for Scientific and Industrial Research, Delhi, India
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35
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Del Toro M, Bucek P, Aviñó A, Jaumot J, González C, Eritja R, Gargallo R. Targeting the G-quadruplex-forming region near the P1 promoter in the human BCL-2 gene with the cationic porphyrin TMPyP4 and with the complementary C-rich strand. Biochimie 2009; 91:894-902. [PMID: 19401211 DOI: 10.1016/j.biochi.2009.04.012] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Accepted: 04/15/2009] [Indexed: 02/05/2023]
Abstract
The B-cell lymphoma-2 (bcl-2) gene contains a region that has been implicated in the regulation of bcl-2 gene expression. This region can form G-quadruplex structures in solution [J.X. Dai, T.S. Dexheimer, D. Chen, M. Carver, A. Ambrus, R.A. Jones, D.Z. Yang, An intramolecular G-quadruplex structure with mixed parallel/antiparallel G-strands formed in the human BCL-2 promoter region in solution, J. Am. Chem. Soc. 128 (2006) 1096-1098.]. Here, we examined the acid-base and conformational equilibria of this G-quadruplex-forming region (BCL2G), as well as its interaction with both the porphyrin TMPyP4 and with the complementary C-rich strand. We used molecular absorption and circular dichroism techniques, in tandem with multivariate analysis tools. The results revealed the formation of an interaction complex BCL2G:TMPyP4 with a stoichiometry of 1:2 and an equilibrium constant equal to 5.0 (+/-2.3) x 10(13) M(-2). Addition of the complementary C-rich strand to BCL2G induces the predominant formation of the Watson-Crick double-helix with an equilibrium constant equal to 10(7.7) M(-1) (at pH 7.1). Finally, the pH-induced formation of quadruplex structures from the Watson-Crick double-helix is characterized.
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Affiliation(s)
- Miquel Del Toro
- Department of Analytical Chemistry, University of Barcelona, Marti i Franques 1-11, E-08028 Barcelona, Spain
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36
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Kumar N, Basundra R, Maiti S. Elevated polyamines induce c-MYC overexpression by perturbing quadruplex-WC duplex equilibrium. Nucleic Acids Res 2009; 37:3321-31. [PMID: 19324889 PMCID: PMC2691834 DOI: 10.1093/nar/gkp196] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The biological role of quadruplexes and polyamines has been independently associated with cancer. However, quadruplex-polyamine mediated transcriptional regulation remain unaddressed. Herein, using c-MYC quadruplex model, we have attempted to understand quadruplex–polyamine interaction and its role in transcriptional regulation. We initially employed biophysical approach involving CD, UV and FRET to understand the role of polyamines (spermidine and spermine) on conformation, stability, molecular recognition of quadruplex and to investigate the effect of polyamines on quadruplex–Watson Crick duplex transition. Our study demonstrates that polyamines affect the c-MYC quadruplex conformation, perturb its recognition properties and delays duplex formation. The relative free energy difference (ΔΔG°) between the duplex and quadruplex structure indicate that polyamines stabilize and favor c-MYC quadruplex over duplex. Further, we investigated the influence of polyamine mediated perturbation of this equilibrium on c-MYC expression. Our results suggest that polyamines induce structural transition of c-MYC quadruplex to a transcriptionally active motif with distinctive molecular recognition property, which drives c-MYC expression. These findings may allow exploiting quadruplex–polyamines interaction for developing antiproliferative strategies to combat aberrant gene expression.
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Affiliation(s)
| | | | - Souvik Maiti
- *To whom correspondence should be addressed. Tel: +91 11 2766 6156; Fax: +91 11 2766 7471; ,
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37
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Zhang JL, Fu Y, Zheng L, Li W, Li H, Sun Q, Xiao Y, Geng F. Natural isoflavones regulate the quadruplex-duplex competition in human telomeric DNA. Nucleic Acids Res 2009; 37:2471-82. [PMID: 19261597 PMCID: PMC2677859 DOI: 10.1093/nar/gkp055] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Effects of natural isoflavones on the structural competition of human telomeric G-quadruplex d[AG(3)(T(2)AG(3))(3)] and its related Watson-Crick duplex d[AG(3)(T(2)AG(3))(3)-(C(3)TA(2))(3)C(3)T] are investigated by using circular dichroism (CD), ESI-MS, fluorescence quenching measurement, CD stopped-flow kinetic experiment, UV spectroscopy and molecular modeling methods. It is intriguing to find out that isoflavones can stabilize the G-quadruplex structure but destabilize its corresponding Watson-Crick duplex and this discriminated interaction is intensified by molecular crowding environments. Kinetic experiments indicate that the dissociation rate of quadruplex (k(obs290 nm)) is decreased by 40.3% at the daidzin/DNA molar ratio of 1.0 in K(+), whereas in Na(+) the observed rate constant is reduced by about 12.0%. Furthermore, glycosidic daidzin significantly induces a structural transition of the polymorphic G-quadruplex into the antiparallel conformation in K(+). This is the first report on the recognition of isoflavones with conformational polymorphism of G-quadruplex, which suggests that natural isoflavone constituents potentially exhibit distinct regulation on the structural competition of quadruplex versus duplex in human telomeric DNA.
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Affiliation(s)
- Jin-li Zhang
- Key Laboratory of Systems Bioengineering, Ministry of Education, School of Chemical Engineering & Technology, Tianjin University, Tianjin 300072, China
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38
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Olsen CM, Lee HT, Marky LA. Unfolding Thermodynamics of Intramolecular G-Quadruplexes: Base Sequence Contributions of the Loops. J Phys Chem B 2008; 113:2587-95. [DOI: 10.1021/jp806853n] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Chris M. Olsen
- Department of Pharmaceutical Sciences, Department of Biochemistry and Molecular Biology, and Eppley Institute for Cancer Research, University of Nebraska Medical Center, Omaha, Nebraska 68198-6025
| | - Hui-Ting Lee
- Department of Pharmaceutical Sciences, Department of Biochemistry and Molecular Biology, and Eppley Institute for Cancer Research, University of Nebraska Medical Center, Omaha, Nebraska 68198-6025
| | - Luis A. Marky
- Department of Pharmaceutical Sciences, Department of Biochemistry and Molecular Biology, and Eppley Institute for Cancer Research, University of Nebraska Medical Center, Omaha, Nebraska 68198-6025
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39
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Kumar N, Maiti S. A thermodynamic overview of naturally occurring intramolecular DNA quadruplexes. Nucleic Acids Res 2008; 36:5610-22. [PMID: 18757890 PMCID: PMC2553590 DOI: 10.1093/nar/gkn543] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Loop length and its composition are important for the structural and functional versatility of quadruplexes. To date studies on the loops have mainly concerned model sequences compared with naturally occurring quadruplex sequences which have diverse loop lengths and compositions. Herein, we have characterized 36 quadruplex-forming sequences from the promoter regions of various proto-oncogenes using CD, UV and native gel electrophoresis. We examined folding topologies and determined the thermodynamic profile for quadruplexes varying in total loop length (5–18 bases) and composition. We found that naturally occurring quadruplexes have variable thermodynamic stabilities (ΔG37) ranging from −1.7 to −15.6 kcal/mol. Overall, our results suggest that both loop length and its composition affect quadruplex structure and thermodynamics, thus making it difficult to draw generalized correlations between loop length and thermodynamic stability. Additionally, we compared the thermodynamic stability of quadruplexes and their respective duplexes to understand quadruplex–duplex competition. Our findings invoke a discussion on whether biological function is associated with quadruplexes with lower thermodynamic stability which undergo facile formation and disruption, or by quadruplexes with high thermodynamic stability.
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Affiliation(s)
- Niti Kumar
- Proteomics and Structural Biology Unit, Institute of Genomics and Integrative Biology, CSIR, Mall Road, Delhi 110 007, India
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40
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Kumar N, Sahoo B, Varun KAS, Maiti S, Maiti S. Effect of loop length variation on quadruplex-Watson Crick duplex competition. Nucleic Acids Res 2008; 36:4433-42. [PMID: 18599514 PMCID: PMC2490738 DOI: 10.1093/nar/gkn402] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
The effect of loop length on quadruplex stability has been studied when the G-rich strand is present along with its complementary C-rich strand, thereby resulting in competition between quadruplex and duplex structures. Using model sequences with loop lengths varying from T to T5, we carried out extensive FRET to discover the influence of loop length on the quadruplex-Watson Crick duplex competition. The binding data show an increase in the binding affinity of quadruplexes towards their complementary strands upon increasing the loop length. Our kinetic data reveal that unfolding of the quadruplex in presence of a complementary strand involves a contribution from a predominant slow and a small population of fast opening conformer. The contribution from the fast opening conformer increases upon increasing the loop length leading to faster duplex formation. FCS data show an increase in the interconversion between the quadruplex conformers in presence of the complementary strand, which shifts the equilibrium towards the fast opening conformer with an increase in loop length. The relative free-energy difference (ΔΔG°) between the duplex and quadruplex indicates that an increase in loop length favors duplex formation and out competes the quadruplex.
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Affiliation(s)
- Niti Kumar
- Proteomics and Structural Biology Unit, Institute of Genomics and Integrative Biology, CSIR, Mall Road, Delhi 110 007, India
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41
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Arora A, Dutkiewicz M, Scaria V, Hariharan M, Maiti S, Kurreck J. Inhibition of translation in living eukaryotic cells by an RNA G-quadruplex motif. RNA (NEW YORK, N.Y.) 2008; 14:1290-6. [PMID: 18515550 PMCID: PMC2441988 DOI: 10.1261/rna.1001708] [Citation(s) in RCA: 175] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Guanine-rich sequences can adopt intramolecular four-stranded structures, called G-quadruplexes. These motifs have been intensively investigated on the DNA level, but their overall biological relevance remains elusive. Only recently has research concerning the function of G-quadruplexes in RNAs commenced. Here, we demonstrate for the first time, that an RNA G-quadruplex structure inhibits translation in vivo in eukaryotic cells. We investigated the function of a highly conserved, thermodynamically stable RNA G-quadruplex in the 5'-UTR of the mRNA of the human Zic-1 zinc-finger protein. Using dual luciferase reporter assay, we demonstrate that the Zic-1 RNA G-quadruplex represses protein synthesis inside eukaryotic cells. Quantitative RT-PCR assays confirmed that the reduction of protein synthesis is due to regulation of the translation process and not a consequence of reduced transcription. Western blot analysis revealed that expression of Zic-1 is strongly reduced by a 73 nucleotides-long fragment of the UTR containing the G-quadruplex motif. These structures might add to the more recently discovered elements in untranslated regions of mRNAs that regulate their translation.
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Affiliation(s)
- Amit Arora
- Institute for Chemistry and Biochemistry, Free University of Berlin, Berlin, Germany
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42
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Kurz M. Compatible solute influence on nucleic acids: many questions but few answers. SALINE SYSTEMS 2008; 4:6. [PMID: 18522725 PMCID: PMC2430576 DOI: 10.1186/1746-1448-4-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/21/2008] [Accepted: 06/03/2008] [Indexed: 12/21/2022]
Abstract
Compatible solutes are small organic osmolytes including but not limited to sugars, polyols, amino acids, and their derivatives. They are compatible with cell metabolism even at molar concentrations. A variety of organisms synthesize or take up compatible solutes for adaptation to extreme environments. In addition to their protective action on whole cells, compatible solutes display significant effects on biomolecules in vitro. These include stabilization of native protein and nucleic acid structures. They are used as additives in polymerase chain reactions to increase product yield and specificity, but also in other nucleic acid and protein applications. Interactions of compatible solutes with nucleic acids and protein-nucleic acid complexes are much less understood than the corresponding interactions of compatible solutes with proteins. Although we may begin to understand solute/nucleic acid interactions there are only few answers to the many questions we have. I summarize here the current state of knowledge and discuss possible molecular mechanisms and thermodynamics.
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Affiliation(s)
- Matthias Kurz
- Institut für Mikrobiologie & Biotechnologie, Rheinische Friedrich Wilhelms-Universität Bonn, Bonn, Germany.
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43
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Saxena S, Bansal A, Kukreti S. Structural polymorphism exhibited by a homopurine.homopyrimidine sequence found at the right end of human c-jun protooncogene. Arch Biochem Biophys 2008; 471:95-108. [PMID: 18262488 DOI: 10.1016/j.abb.2008.01.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2007] [Revised: 01/15/2008] [Accepted: 01/19/2008] [Indexed: 11/17/2022]
Abstract
Homopurine.homopyrimidine (Pu.Py) tracts are likely to play important biological role in eukaryotes. Using circular dichroism, UV-thermal denaturation and gel electrophoresis, we have analyzed the structural polymorphism of a 21-bp Pu.Py DNA segment within human c-jun protooncogene 3'-region, a potential target for triplex formation. Results show that below physiological pH and in the presence of Na+/K+ with Mg2+ the duplex is destabilized/disproportionated, resulting in strand mediated structural transitions to the self-associated structures of G- and C-rich strands separately, identified as G-quadruplex and i-motif species. A significant differential behavior of the monovalent cations was observed, accordingly the presence of Na+ in acidic as well as neutral pH facilitated the duplex formation, while K+ favored the formation of self-associated structures. In Na+ and Mg2+, under acidic and neutral pH conditions, the duplex displayed triphasic and biphasic melting profiles, respectively. This self-association property of oligonucleotides might limit their use as duplex targets in triplex formation. Study is also relevant for understanding structural and biological properties of DNA sequence containing homopurine tracts.
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Affiliation(s)
- Sarika Saxena
- Nucleic Acids Research Laboratory, Department of Chemistry, University of Delhi (North Campus), Delhi 110007, India
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44
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Kumar N, Maiti S. Role of locked nucleic acid modified complementary strand in quadruplex/Watson-Crick duplex equilibrium. J Phys Chem B 2007; 111:12328-37. [PMID: 17914789 DOI: 10.1021/jp072705u] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In the human genome, the G-rich sequences that form quadruplexes are present along with their C-rich complementary strands; this suggests the existence of equilibrium between a quadruplex and a Watson-Crick duplex which allows the execution of their respective biological functions. We have investigated the sensitivity of this equilibrium to pharmacological agents by employing locked nucleic acid (LNA) modified complementary strands, and demonstrated successful invasion of the stable telomeric quadruplex d[(G(3)TTA)(3)G(3)]. Fluorescence, UV, ITC, and SPR studies were performed to understand the binding process involving the preformed quadruplex and LNA-modified complementary strands compared with that involving the unmodified complementary strand. Our data indicate that LNA modifications in the complementary strand shift the equilibrium toward the duplex state. These modifications confer increased thermodynamic stability to the duplex and increase the magnitude of relative free energy (DeltaDeltaG degrees) difference between duplex and quadruplex, thus favoring the predominance of duplex population over quadruplex. This superior ability of LNA-modified complementary strand can be exploited to pave an exploratory approach in which it hybridizes to a telomeric quadruplex and drives duplex formation, and inhibits the recognition of 3' G-rich overhang by RNA template of telomerase which guides telomere extension.
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Affiliation(s)
- Niti Kumar
- Proteomics and Structural Biology Unit, Institute of Genomics and Integrative Biology, CSIR, Mall Road, New Delhi 110 007, India
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45
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Kan ZY, Lin Y, Wang F, Zhuang XY, Zhao Y, Pang DW, Hao YH, Tan Z. G-quadruplex formation in human telomeric (TTAGGG)4 sequence with complementary strand in close vicinity under molecularly crowded condition. Nucleic Acids Res 2007; 35:3646-53. [PMID: 17488850 PMCID: PMC1920240 DOI: 10.1093/nar/gkm203] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Chromosomes in vertebrates are protected at both ends by telomere DNA composed of tandem (TTAGGG)n repeats. DNA replication produces a blunt-ended leading strand telomere and a lagging strand telomere carrying a single-stranded G-rich overhang at its end. The G-rich strand can form G-quadruplex structure in the presence of K+ or Na+. At present, it is not clear whether quadruplex can form in the double-stranded telomere region where the two complementary strands are constrained in close vicinity and quadruplex formation, if possible, has to compete with the formation of the conventional Watson-Crick duplex. In this work, we studied quadruplex formation in oligonucleotides and double-stranded DNA containing both the G- and C-rich sequences to better mimic the in vivo situation. Under such competitive condition only duplex was observed in dilute solution containing physiological concentration of K+. However, quadruplex could preferentially form and dominate over duplex structure under molecular crowding condition created by PEG as a result of significant quadruplex stabilization and duplex destabilization. This observation suggests quadruplex may potentially form or be induced at the blunt end of a telomere, which may present a possible alternative form of structures at telomere ends.
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Affiliation(s)
- Zhong-yuan Kan
- Laboratory of Biochemistry and Biophysics, College of Life Sciences, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, P. R. China and State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, P. R. China
| | - Yi Lin
- Laboratory of Biochemistry and Biophysics, College of Life Sciences, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, P. R. China and State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, P. R. China
| | - Feng Wang
- Laboratory of Biochemistry and Biophysics, College of Life Sciences, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, P. R. China and State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, P. R. China
| | - Xin-ying Zhuang
- Laboratory of Biochemistry and Biophysics, College of Life Sciences, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, P. R. China and State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, P. R. China
| | - Yong Zhao
- Laboratory of Biochemistry and Biophysics, College of Life Sciences, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, P. R. China and State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, P. R. China
| | - Dai-wen Pang
- Laboratory of Biochemistry and Biophysics, College of Life Sciences, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, P. R. China and State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, P. R. China
| | - Yu-hua Hao
- Laboratory of Biochemistry and Biophysics, College of Life Sciences, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, P. R. China and State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, P. R. China
| | - Zheng Tan
- Laboratory of Biochemistry and Biophysics, College of Life Sciences, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, P. R. China and State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, P. R. China
- *To whom correspondence should be addressed. +86 27 6875 4351+86 27 6875 6661, The authors wish it to be known that, in their opinion, the first three authors should be regarded as joint First Authors
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46
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Abstract
Stabilization of nucleic acid structures results from a balance of multiple interactions, including electrostatics, base stacking, hydrophobic interactions, hydrogen bonding, van der Waals forces, etc. Nucleic acid quadruplexes are unusual structures in that their formation is driven by specific binding of metal ions. This unique mode of metal binding, which is tightly coupled to oligonucleotide folding, can engender correspondingly unique solution behavior. In particular, we show that addition of many cosolvents, such as primary aliphatic alcohols, increases the thermal stability of quadruplexes, as determined by melting temperature, Tm, in direct contrast to the response of duplexes to the same admixture of solvents. Thermal stability is observed to increase as the dielectric constant of the composite solvent decreases. This behavior suggests a dominant role for electrostatics in quadruplex formation and stability. Additional studies done with other cosolvents and solutes suggest that, in some cases, other forces may come into play, including the possibility of direct interaction with the quadruplex structure. Nonetheless, many cosolvents and small molecules, such as ethanol, dimethylformamide, and betaine, stabilize the quadruplex conformation in sharp distinction to their destabilization of DNA duplexes.
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Affiliation(s)
- Ivan V Smirnov
- Department of Pharmaceutical Chemistry, School of Pharmacy, University of California, San Francisco, CA 94143-0446, USA
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47
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Freyer MW, Buscaglia R, Kaplan K, Cashman D, Hurley LH, Lewis EA. Biophysical studies of the c-MYC NHE III1 promoter: model quadruplex interactions with a cationic porphyrin. Biophys J 2006; 92:2007-15. [PMID: 17172304 PMCID: PMC1861781 DOI: 10.1529/biophysj.106.097246] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Regulation of the structural equilibrium of G-quadruplex-forming sequences located in the promoter regions of oncogenes by the binding of small molecules has shown potential as a new avenue for cancer chemotherapy. In this study, microcalorimetry (isothermal titration calorimetry and differential scanning calorimetry), electronic spectroscopy (ultraviolet-visible and circular dichroism), and molecular modeling were used to probe the complex interactions between a cationic porphryin mesotetra (N-methyl-4-pyridyl) porphine (TMPyP4) and the c-MYC PU 27-mer quadruplex. The stoichiometry at saturation is 4:1 mol of TMPyP4/c-MYC PU 27-mer G-quadruplex as determined by isothermal titration calorimetry, circular dichroism, and ultraviolet-visible spectroscopy. The four independent TMPyP4 binding sites fall into one of two modes. The two binding modes are different with respect to affinity, enthalpy change, and entropy change for formation of the 1:1 and 2:1, or 3:1 and 4:1 complexes. Binding of TMPyP4, at or near physiologic ionic strength ([K(+)] = 0.13 M), is described by a "two-independent-sites model." The two highest-affinity sites exhibit a K(1) of 1.6 x 10(7) M(-1) and the two lowest-affinity sites exhibit a K(2) of 4.2 x 10(5) M(-1). Dissection of the free-energy change into the enthalpy- and entropy-change contributions for the two modes is consistent with both "intercalative" and "exterior" binding mechanisms. An additional complexity is that there may be as many as six possible conformational quadruplex isomers based on the sequence. Differential scanning calorimetry experiments demonstrated two distinct melting events (T(m)1 = 74.7 degrees C and T(m)2 = 91.2 degrees C) resulting from a mixture of at least two conformers for the c-MYC PU 27-mer in solution.
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Affiliation(s)
- Matthew W Freyer
- Department of Chemistry and Biochemistry, Northern Arizona University, Flagstaff, Arizona, USA
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48
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Miyoshi D, Inoue M, Sugimoto N. DNA Logic Gates Based on Structural Polymorphism of Telomere DNA Molecules Responding to Chemical Input Signals. Angew Chem Int Ed Engl 2006; 45:7716-9. [PMID: 17031891 DOI: 10.1002/anie.200602404] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Daisuke Miyoshi
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, Japan
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49
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Miyoshi D, Inoue M, Sugimoto N. DNA Logic Gates Based on Structural Polymorphism of Telomere DNA Molecules Responding to Chemical Input Signals. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200602404] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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50
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Salas TR, Petruseva I, Lavrik O, Bourdoncle A, Mergny JL, Favre A, Saintomé C. Human replication protein A unfolds telomeric G-quadruplexes. Nucleic Acids Res 2006; 34:4857-65. [PMID: 16973897 PMCID: PMC1635258 DOI: 10.1093/nar/gkl564] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
G-quadruplex structures inhibit telomerase activity and must be disrupted for telomere elongation during S phase. It has been suggested that the replication protein A (RPA) could unwind and maintain single-stranded DNA in a state amenable to the binding of telomeric components. We show here that under near-physiological in vitro conditions, human RPA is able to bind and unfold G-quadruplex structures formed from a 21mer human telomeric sequence. Analyses by native gel electrophoresis, cross-linking and fluorescence resonance energy transfer indicate the formation of both 1:1 and 2:1 complexes in which G-quadruplexes are unfolded. In addition, quadruplex opening by hRPA is much faster than observed with the complementary DNA, demonstrating that this protein efficiently unfolds G-quartets. A two-step mechanism accounting for the binding of hRPA to G-quadruplexes is proposed. These data point to the involvement of hRPA in regulation of telomere maintenance.
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Affiliation(s)
| | - Irina Petruseva
- Novosibirsk Institute of Bioorganic Chemistry, Siberian Division of Russian Academy of Sciences630090 Novosibirsk, Russia
| | - Olga Lavrik
- Novosibirsk Institute of Bioorganic Chemistry, Siberian Division of Russian Academy of Sciences630090 Novosibirsk, Russia
| | - Anne Bourdoncle
- Laboratoire de Biophysique, INSERM U565, CNRS UMR 5153, Muséum National d'Histoire Naturelle USM 50343 rue Cuvier, 75005 Paris, France
| | - Jean-Louis Mergny
- Laboratoire de Biophysique, INSERM U565, CNRS UMR 5153, Muséum National d'Histoire Naturelle USM 50343 rue Cuvier, 75005 Paris, France
| | | | - Carole Saintomé
- To whom correspondence should be addressed. Tel: +33 1 44 27 40 86; Fax: +33 1 44 27 57 16;
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