1
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Smith SS. The bisulfite reaction with cytosine and genomic DNA structure. Anal Biochem 2024; 691:115532. [PMID: 38609028 DOI: 10.1016/j.ab.2024.115532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2023] [Revised: 02/19/2024] [Accepted: 04/04/2024] [Indexed: 04/14/2024]
Abstract
The bisulfite reaction with native DNA has been extensively employed in the detection of non-B DNA structures that can form spontaneously in DNA. These sequences are dynamic in that they can adopt both normal Watson-Crick paired B-DNA or unusual structures like the Triplex, G-Quadruplex, i-motif and Cruciform or Hairpin. Considerable evidence now suggests that these dynamic sequences play roles in both epigenetics and mutagenesis. The bisulfite reaction with native DNA offers a key approach to their detection. In this application whole cells, isolated nuclei or isolated DNA are treated with bisulfite under non-denaturing conditions in order to detect bisulfite accessible regions DNA that are associated with these structures. Here I review the stereochemistry of the bisulfite reaction, the electronic structure of its DNA cytosine substrates and its application in the detection of unusual structures in native DNA.
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Affiliation(s)
- Steven S Smith
- Department of Stem Cell Biology and Regenerative Medicine, Beckman Research Institute of the City of Hope, Duarte, CA, USA.
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2
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Guneri D, Waller ZAE. Utility of intercalator displacement assays for screening of ligands for i-motif DNA structures. Methods Enzymol 2024; 695:221-232. [PMID: 38521586 DOI: 10.1016/bs.mie.2023.12.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/25/2024]
Abstract
Cytosine rich sequences can form intercalated, i-motif DNA structures stabilized by hemi-protonated cytosine:cytosine base pairing. These sequences are often located in regulatory regions of genes such as promoters. Ligands targeting i-motif structures may provide potential leads for treatments for genetic disease. The focus on ligands interacting with i-motif DNA has been increasing in recent years. Here, we describe the fluorescent intercalator displacement (FID) assay using thiazole orange binding i-motif DNA and assess the binding affinity of a ligand to the i-motif DNA by displacing thiazole orange. This provides a time and cost-effective high throughput screening of ligands against secondary DNA structures for hit identification.
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Affiliation(s)
- Dilek Guneri
- School of Pharmacy, University College London, London, United Kingdom.
| | - Zoë A E Waller
- School of Pharmacy, University College London, London, United Kingdom.
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3
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Smirnov E, Molínová P, Chmúrčiaková N, Vacík T, Cmarko D. Non-canonical DNA structures in the human ribosomal DNA. Histochem Cell Biol 2023; 160:499-515. [PMID: 37750997 DOI: 10.1007/s00418-023-02233-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/15/2023] [Indexed: 09/27/2023]
Abstract
Non-canonical structures (NCS) refer to the various forms of DNA that differ from the B-conformation described by Watson and Crick. It has been found that these structures are usual components of the genome, actively participating in its essential functions. The present review is focused on the nine kinds of NCS appearing or likely to appear in human ribosomal DNA (rDNA): supercoiling structures, R-loops, G-quadruplexes, i-motifs, DNA triplexes, cruciform structures, DNA bubbles, and A and Z DNA conformations. We discuss the conditions of their generation, including their sequence specificity, distribution within the locus, dynamics, and beneficial and detrimental role in the cell.
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Affiliation(s)
- Evgeny Smirnov
- Laboratory of Cell Biology, Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, 128 00, Prague, Czech Republic.
| | - Pavla Molínová
- Laboratory of Cell Biology, Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, 128 00, Prague, Czech Republic
| | - Nikola Chmúrčiaková
- Laboratory of Cell Biology, Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, 128 00, Prague, Czech Republic
| | - Tomáš Vacík
- Laboratory of Cell Biology, Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, 128 00, Prague, Czech Republic
| | - Dušan Cmarko
- Laboratory of Cell Biology, Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, 128 00, Prague, Czech Republic
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4
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Duardo RC, Guerra F, Pepe S, Capranico G. Non-B DNA structures as a booster of genome instability. Biochimie 2023; 214:176-192. [PMID: 37429410 DOI: 10.1016/j.biochi.2023.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 07/04/2023] [Accepted: 07/06/2023] [Indexed: 07/12/2023]
Abstract
Non-canonical secondary structures (NCSs) are alternative nucleic acid structures that differ from the canonical B-DNA conformation. NCSs often occur in repetitive DNA sequences and can adopt different conformations depending on the sequence. The majority of these structures form in the context of physiological processes, such as transcription-associated R-loops, G4s, as well as hairpins and slipped-strand DNA, whose formation can be dependent on DNA replication. It is therefore not surprising that NCSs play important roles in the regulation of key biological processes. In the last years, increasing published data have supported their biological role thanks to genome-wide studies and the development of bioinformatic prediction tools. Data have also highlighted the pathological role of these secondary structures. Indeed, the alteration or stabilization of NCSs can cause the impairment of transcription and DNA replication, modification in chromatin structure and DNA damage. These events lead to a wide range of recombination events, deletions, mutations and chromosomal aberrations, well-known hallmarks of genome instability which are strongly associated with human diseases. In this review, we summarize molecular processes through which NCSs trigger genome instability, with a focus on G-quadruplex, i-motif, R-loop, Z-DNA, hairpin, cruciform and multi-stranded structures known as triplexes.
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Affiliation(s)
- Renée C Duardo
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum University of Bologna, via Selmi 3, 40126, Bologna, Italy
| | - Federico Guerra
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum University of Bologna, via Selmi 3, 40126, Bologna, Italy
| | - Simona Pepe
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum University of Bologna, via Selmi 3, 40126, Bologna, Italy
| | - Giovanni Capranico
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum University of Bologna, via Selmi 3, 40126, Bologna, Italy.
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5
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Conrad JW, Sowers ML, Yap DY, Cherryhomes E, Pettitt BM, Khanipov K, Sowers LC. Transition Mutations in the hTERT Promoter Are Unrelated to Potential i-motif Formation in the C-Rich Strand. Biomolecules 2023; 13:1308. [PMID: 37759708 PMCID: PMC10526324 DOI: 10.3390/biom13091308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 08/14/2023] [Accepted: 08/18/2023] [Indexed: 09/29/2023] Open
Abstract
Increased expression of the human telomere reverse transcriptase (hTERT) in tumors promotes tumor cell survival and diminishes the survival of patients. Cytosine-to-thymine (C-to-T) transition mutations (C250T or C228T) in the hTERT promoter create binding sites for transcription factors, which enhance transcription. The G-rich strand of the hTERT promoter can form G-quadruplex structures, whereas the C-rich strand can form an i-motif in which multiple cytosine residues are protonated. We considered the possibility that i-motif formation might promote cytosine deamination to uracil and C-to-T mutations. We computationally probed the accessibility of cytosine residues in an i-motif to attack by water. We experimentally examined regions of the C-rich strand to form i-motifs using pH-dependent UV and CD spectra. We then incubated the C-rich strand with and without the G-rich complementary strand DNA under various conditions, followed by deep sequencing. Surprisingly, deamination rates did not vary substantially across the 46 cytosines examined, and the two mutation hotspots were not deamination hotspots. The appearance of mutational hotspots in tumors is more likely the result of the selection of sequences with increased promoter binding affinity and hTERT expression.
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Affiliation(s)
- James W. Conrad
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Mark L. Sowers
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Galveston, TX 77555, USA
- MD-PhD Combined Degree Program, The University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Dianne Y. Yap
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Ellie Cherryhomes
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Galveston, TX 77555, USA
| | - B. Montgomery Pettitt
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Galveston, TX 77555, USA
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Kamil Khanipov
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Lawrence C. Sowers
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Galveston, TX 77555, USA
- Department of Internal Medicine, The University of Texas Medical Branch, Galveston, TX 77555, USA
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6
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Zhang ZH, Qian SH, Wei D, Chen ZX. In vivo dynamics and regulation of DNA G-quadruplex structures in mammals. Cell Biosci 2023; 13:117. [PMID: 37381029 DOI: 10.1186/s13578-023-01074-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Accepted: 06/19/2023] [Indexed: 06/30/2023] Open
Abstract
G-quadruplex (G4) is a four-stranded helical DNA secondary structure formed by guanine-rich sequence folding, and G4 has been computationally predicted to exist in a wide range of species. Substantial evidence has supported the formation of endogenous G4 (eG4) in living cells and revealed its regulatory dynamics and critical roles in several important biological processes, making eG4 a regulator of gene expression perturbation and a promising therapeutic target in disease biology. Here, we reviewed the methods for prediction of potential G4 sequences (PQS) and detection of eG4s. We also highlighted the factors affecting the dynamics of eG4s and the effects of eG4 dynamics. Finally, we discussed the future applications of eG4 dynamics in disease therapy.
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Affiliation(s)
- Ze-Hao Zhang
- Hubei Hongshan Laboratory, College of Life Science and Technology, College of Biomedicine and Health, Interdisciplinary Sciences Institute, Huazhong Agricultural University, Wuhan, 430070, China
| | - Sheng Hu Qian
- Hubei Hongshan Laboratory, College of Life Science and Technology, College of Biomedicine and Health, Interdisciplinary Sciences Institute, Huazhong Agricultural University, Wuhan, 430070, China
| | - Dengguo Wei
- College of Science, Huazhong Agricultural University, Wuhan, 430070, China
| | - Zhen-Xia Chen
- Hubei Hongshan Laboratory, College of Life Science and Technology, College of Biomedicine and Health, Interdisciplinary Sciences Institute, Huazhong Agricultural University, Wuhan, 430070, China.
- Shenzhen Institute of Nutrition and Health, Huazhong Agricultural University, Shenzhen, 518000, China.
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518000, China.
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7
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Cadoni E, De Paepe L, Colpaert G, Tack R, Waegeman D, Manicardi A, Madder A. A red light-triggered chemical tool for sequence-specific alkylation of G-quadruplex and I-motif DNA. Nucleic Acids Res 2023; 51:4112-4125. [PMID: 36971129 PMCID: PMC10201448 DOI: 10.1093/nar/gkad189] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 02/03/2023] [Accepted: 03/12/2023] [Indexed: 08/21/2023] Open
Abstract
The importance of non-canonical DNA structures such as G-quadruplexes (G4) and intercalating-motifs (iMs) in the fine regulation of a variety of cellular processes has been recently demonstrated. As the crucial roles of these structures are being unravelled, it is becoming more and more important to develop tools that allow targeting these structures with the highest possible specificity. While targeting methodologies have been reported for G4s, this is not the case for iMs, as evidenced by the limited number of specific ligands able to bind the latter and the total absence of selective alkylating agents for their covalent targeting. Furthermore, strategies for the sequence-specific covalent targeting of G4s and iMs have not been reported thus far. Herein, we describe a simple methodology to achieve sequence-specific covalent targeting of G4 and iM DNA structures based on the combination of (i) a peptide nucleic acid (PNA) recognizing a specific sequence of interest, (ii) a pro-reactive moiety enabling a controlled alkylation reaction, and (iii) a G4 or iM ligand orienting the alkylating warhead to the reactive residues. This multi-component system allows for the targeting of specific G4 or iM sequences of interest in the presence of competing DNA sequences and under biologically relevant conditions.
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Affiliation(s)
- Enrico Cadoni
- Organic and Biomimetic Chemistry Research Group, Ghent University, Krijgslaan 281 S4, B-9000 Ghent, Belgium
| | - Lessandro De Paepe
- Organic and Biomimetic Chemistry Research Group, Ghent University, Krijgslaan 281 S4, B-9000 Ghent, Belgium
| | - Gertjan Colpaert
- Organic and Biomimetic Chemistry Research Group, Ghent University, Krijgslaan 281 S4, B-9000 Ghent, Belgium
| | - Ruben Tack
- Organic and Biomimetic Chemistry Research Group, Ghent University, Krijgslaan 281 S4, B-9000 Ghent, Belgium
| | - Dries Waegeman
- Organic and Biomimetic Chemistry Research Group, Ghent University, Krijgslaan 281 S4, B-9000 Ghent, Belgium
| | - Alex Manicardi
- Organic and Biomimetic Chemistry Research Group, Ghent University, Krijgslaan 281 S4, B-9000 Ghent, Belgium
| | - Annemieke Madder
- Organic and Biomimetic Chemistry Research Group, Ghent University, Krijgslaan 281 S4, B-9000 Ghent, Belgium
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8
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Song YQ, Li GD, Niu D, Chen F, Jing S, Wai Wong VK, Wang W, Leung CH. A robust luminescent assay for screening alkyladenine DNA glycosylase inhibitors to overcome DNA repair and temozolomide drug resistance. J Pharm Anal 2023; 13:514-522. [PMID: 37305785 PMCID: PMC10257196 DOI: 10.1016/j.jpha.2023.04.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 03/22/2023] [Accepted: 04/15/2023] [Indexed: 06/13/2023] Open
Abstract
Temozolomide (TMZ) is an anticancer agent used to treat glioblastoma, typically following radiation therapy and/or surgical resection. However, despite its effectiveness, at least 50% of patients do not respond to TMZ, which is associated with repair and/or tolerance of TMZ-induced DNA lesions. Studies have demonstrated that alkyladenine DNA glycosylase (AAG), an enzyme that triggers the base excision repair (BER) pathway by excising TMZ-induced N3-methyladenine (3meA) and N7-methylguanine lesions, is overexpressed in glioblastoma tissues compared to normal tissues. Therefore, it is essential to develop a rapid and efficient screening method for AAG inhibitors to overcome TMZ resistance in glioblastomas. Herein, we report a robust time-resolved photoluminescence platform for identifying AAG inhibitors with improved sensitivity compared to conventional steady-state spectroscopic methods. As a proof-of-concept, this assay was used to screen 1440 food and drug administration-approved drugs against AAG, resulting in the repurposing of sunitinib as a potential AAG inhibitor. Sunitinib restored glioblastoma (GBM) cancer cell sensitivity to TMZ, inhibited GBM cell proliferation and stem cell characteristics, and induced GBM cell cycle arrest. Overall, this strategy offers a new method for the rapid identification of small-molecule inhibitors of BER enzyme activities that can prevent false negatives due to a fluorescent background.
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Affiliation(s)
- Ying-Qi Song
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, 999078, China
| | - Guo-Dong Li
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, 999078, China
| | - Dou Niu
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, 999078, China
| | - Feng Chen
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, 999078, China
| | - Shaozhen Jing
- Institute of Medical Research, Northwestern Polytechnical University, Xi'an, 710072, China
| | - Vincent Kam Wai Wong
- Dr. Neher's Biophysics Laboratory for Innovative Drug Discovery, State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Macao, 999078, China
| | - Wanhe Wang
- Institute of Medical Research, Northwestern Polytechnical University, Xi'an, 710072, China
| | - Chung-Hang Leung
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, 999078, China
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Macau, Macao, 999078, China
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9
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Lu S, Dai Z, Cui Y, Kong DM. Recent Development of Advanced Fluorescent Molecular Probes for Organelle-Targeted Cell Imaging. BIOSENSORS 2023; 13:360. [PMID: 36979572 PMCID: PMC10046058 DOI: 10.3390/bios13030360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 02/10/2023] [Accepted: 02/20/2023] [Indexed: 06/18/2023]
Abstract
Fluorescent molecular probes are very powerful tools that have been generally applied in cell imaging in the research fields of biology, pathology, pharmacology, biochemistry, and medical science. In the last couple of decades, numerous molecular probes endowed with high specificity to particular organelles have been designed to illustrate intracellular images in more detail at the subcellular level. Nowadays, the development of cell biology has enabled the investigation process to go deeply into cells, even at the molecular level. Therefore, probes that can sketch a particular organelle's location while responding to certain parameters to evaluate intracellular bioprocesses are under urgent demand. It is significant to understand the basic ideas of organelle properties, as well as the vital substances related to each unique organelle, for the design of probes with high specificity and efficiency. In this review, we summarize representative multifunctional fluorescent molecular probes developed in the last decade. We focus on probes that can specially target nuclei, mitochondria, endoplasmic reticulums, and lysosomes. In each section, we first briefly introduce the significance and properties of different organelles. We then discuss how probes are designed to make them highly organelle-specific. Finally, we also consider how probes are constructed to endow them with additional functions to recognize particular physical/chemical signals of targeted organelles. Moreover, a perspective on the challenges in future applications of highly specific molecular probes in cell imaging is also proposed. We hope that this review can provide researchers with additional conceptual information about developing probes for cell imaging, assisting scientists interested in molecular biology, cell biology, and biochemistry to accelerate their scientific studies.
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Affiliation(s)
- Sha Lu
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Research Centre for Analytical Sciences, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Zhiqi Dai
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Research Centre for Analytical Sciences, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Yunxi Cui
- College of Life Sciences, Nankai University, Tianjin 300071, China
| | - De-Ming Kong
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Research Centre for Analytical Sciences, College of Chemistry, Nankai University, Tianjin 300071, China
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10
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Herbert A. Nucleosomes and flipons exchange energy to alter chromatin conformation, the readout of genomic information, and cell fate. Bioessays 2022; 44:e2200166. [DOI: 10.1002/bies.202200166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 09/24/2022] [Accepted: 09/28/2022] [Indexed: 11/27/2022]
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11
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Miglietta G, Marinello J, Russo M, Capranico G. Ligands stimulating antitumour immunity as the next G-quadruplex challenge. Mol Cancer 2022; 21:180. [PMID: 36114513 PMCID: PMC9482198 DOI: 10.1186/s12943-022-01649-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 08/22/2022] [Indexed: 11/10/2022] Open
Abstract
AbstractG-quadruplex (G4) binders have been investigated to discover new anticancer drugs worldwide in past decades. As these ligands are generally not highly cytotoxic, the discovery rational was mainly based on increasing the cell-killing potency. Nevertheless, no G4 binder has been shown yet to be effective in cancer patients. Here, G4 binder activity at low dosages will be discussed as a critical feature to discover ligands with therapeutic effects in cancer patients. Specific effects of G4 binders al low doses have been reported to occur in cancer and normal cells. Among them, genome instability and the stimulation of cytoplasmic processes related to autophagy and innate immune response open to the use of G4 binders as immune-stimulating agents. Thus, we propose a new rational of drug discovery, which is not based on cytotoxic potency but rather on immune gene activation at non-cytotoxic dosage.
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12
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Severov V, Tsvetkov V, Barinov N, Babenko V, Klinov D, Pozmogova G. Spontaneous DNA Synapsis by Forming Noncanonical Intermolecular Structures. Polymers (Basel) 2022; 14:polym14102118. [PMID: 35632001 PMCID: PMC9144187 DOI: 10.3390/polym14102118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 05/14/2022] [Accepted: 05/20/2022] [Indexed: 01/27/2023] Open
Abstract
We report the spontaneous formation of DNA-DNA junctions in solution in the absence of proteins visualised using atomic force microscopy. The synapsis position fits with potential G-quadruplex (G4) sites. In contrast to the Holliday structure, these conjugates have an affinity for G4 antibodies. Molecular modelling was used to elucidate the possible G4/IM-synaptic complex structures. Our results indicate a new role of the intermolecular noncanonical structures in chromatin architecture and genomic rearrangement.
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Affiliation(s)
- Viacheslav Severov
- Federal Research and Clinical Center of Physical-Chemical Medicine, Malaya Pirogovskaya Str. 1a, 119435 Moscow, Russia; (N.B.); (V.B.); (D.K.); (G.P.)
- Correspondence: (V.S.); (V.T.)
| | - Vladimir Tsvetkov
- Federal Research and Clinical Center of Physical-Chemical Medicine, Malaya Pirogovskaya Str. 1a, 119435 Moscow, Russia; (N.B.); (V.B.); (D.K.); (G.P.)
- Institute of Biodesign and Complex System Modeling, I.M. Sechenov First Moscow State Medical University, Trubetskaya Str. 8-2, 119991 Moscow, Russia
- A.V. Topchiev Institute of Petrochemical Synthesis, Leninsky prospect Str. 29, 119991 Moscow, Russia
- Correspondence: (V.S.); (V.T.)
| | - Nikolay Barinov
- Federal Research and Clinical Center of Physical-Chemical Medicine, Malaya Pirogovskaya Str. 1a, 119435 Moscow, Russia; (N.B.); (V.B.); (D.K.); (G.P.)
| | - Vladislav Babenko
- Federal Research and Clinical Center of Physical-Chemical Medicine, Malaya Pirogovskaya Str. 1a, 119435 Moscow, Russia; (N.B.); (V.B.); (D.K.); (G.P.)
| | - Dmitry Klinov
- Federal Research and Clinical Center of Physical-Chemical Medicine, Malaya Pirogovskaya Str. 1a, 119435 Moscow, Russia; (N.B.); (V.B.); (D.K.); (G.P.)
- Peoples’ Friendship University of Russia (RUDN University), 6 Miklukho-Maklaya str.6, 117198 Moscow, Russia
| | - Galina Pozmogova
- Federal Research and Clinical Center of Physical-Chemical Medicine, Malaya Pirogovskaya Str. 1a, 119435 Moscow, Russia; (N.B.); (V.B.); (D.K.); (G.P.)
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13
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Frasson I, Pirota V, Richter SN, Doria F. Multimeric G-quadruplexes: A review on their biological roles and targeting. Int J Biol Macromol 2022; 204:89-102. [PMID: 35124022 DOI: 10.1016/j.ijbiomac.2022.01.197] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 01/20/2022] [Accepted: 01/31/2022] [Indexed: 12/12/2022]
Abstract
In human cells, nucleic acids adopt several non-canonical structures that regulate key cellular processes. Among them, G-quadruplexes (G4s) are stable structures that form in guanine-rich regions in vitro and in cells. G4 folded/unfolded state shapes numerous cellular processes, including genome replication, transcription, and translation. Moreover, G4 folding is involved in genomic instability. G4s have been described to multimerize, forming high-order structures in both DNA and/or RNA strands. Multimeric G4s can be formed by adjacent intramolecular G4s joined by stacking interactions or connected by short loops. Multimeric G4s can also originate from the assembly of guanines embedded on independent DNA or RNA strands. Notably, crucial regions of the human genome, such as the 3'-terminal overhang of the telomeric DNA as well as the open reading frame of genes involved in the preservation of neuron viability in the human central and peripheral nervous system are prone to form multimeric G4s. The biological importance of such structures has been recently described, with multimeric G4s playing potentially protective or deleterious effects in the pathogenic cascade of various diseases. Here, we portray the multifaceted scenario of multimeric G4s, in terms of structural properties, biological roles, and targeting strategies.
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Affiliation(s)
- Ilaria Frasson
- Department of Molecular Medicine, University of Padova, via A. Gabelli 63, 35121 Padova, Italy
| | - Valentina Pirota
- Department of Chemistry, University of Pavia, v. le Taramelli 10, 27100 Pavia, Italy; G4-INTERACT, USERN, v. le Taramelli 10, 27100 Pavia, Italy
| | - Sara N Richter
- Department of Molecular Medicine, University of Padova, via A. Gabelli 63, 35121 Padova, Italy.
| | - Filippo Doria
- Department of Chemistry, University of Pavia, v. le Taramelli 10, 27100 Pavia, Italy.
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14
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Martella M, Pichiorri F, Chikhale RV, Abdelhamid MAS, Waller ZAE, Smith S. i-Motif formation and spontaneous deletions in human cells. Nucleic Acids Res 2022; 50:3445-3455. [PMID: 35253884 PMCID: PMC8989526 DOI: 10.1093/nar/gkac158] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Revised: 02/01/2022] [Accepted: 02/26/2022] [Indexed: 01/14/2023] Open
Abstract
Concatemers of d(TCCC) that were first detected through their association with deletions at the RACK7 locus, are widespread throughout the human genome. Circular dichroism spectra show that d(GGGA)n sequences form G-quadruplexes when n > 3, while i-motif structures form at d(TCCC)n sequences at neutral pH when n ≥ 7 in vitro. In the PC3 cell line, deletions are observed only when the d(TCCC)n variant is long enough to form significant levels of unresolved i-motif structure at neutral pH. The presence of an unresolved i-motif at a representative d(TCCC)n element at RACK7 was suggested by experiments showing that that the region containing the d(TCCC)9 element was susceptible to bisulfite attack in native DNA and that d(TCCC)9 oligo formed an i-motif structure at neutral pH. This in turn suggested that that the i-motif present at this site in native DNA must be susceptible to bisulfite mediated deamination even though it is a closed structure. Bisulfite deamination of the i-motif structure in the model oligodeoxynucleotide was confirmed using mass spectrometry analysis. We conclude that while G-quadruplex formation may contribute to spontaneous mutation at these sites, deletions actually require the potential for i-motif to form and remain unresolved at neutral pH.
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Affiliation(s)
- Marianna Martella
- Judy and Bernard Briskin Center for Multiple Myeloma Research, City of Hope, 1500 E. Duarte Rd., Duarte, CA 91010, USA
| | - Flavia Pichiorri
- Judy and Bernard Briskin Center for Multiple Myeloma Research, City of Hope, 1500 E. Duarte Rd., Duarte, CA 91010, USA
| | - Rupesh V Chikhale
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
- UCL School of Pharmacy, 29-39 Brunswick Square, London WC1N 1AX, UK
| | - Mahmoud A S Abdelhamid
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Zoë A E Waller
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
- UCL School of Pharmacy, 29-39 Brunswick Square, London WC1N 1AX, UK
| | - Steven S Smith
- Department of Hematologic Malignancies Translational Science, City of Hope, 1500 E. Duarte Rd., Duarte, CA 91010, USA
- Beckman Research Institute of the City of Hope, 1500 E. Duarte Rd., Duarte, CA 91010, USA
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15
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Stability and context of intercalated motifs (i-motifs) for biological applications. Biochimie 2022; 198:33-47. [PMID: 35259471 DOI: 10.1016/j.biochi.2022.03.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 02/21/2022] [Accepted: 03/03/2022] [Indexed: 11/24/2022]
Abstract
DNA is naturally dynamic and can self-assemble into alternative secondary structures including the intercalated motif (i-motif), a four-stranded structure formed in cytosine-rich DNA sequences. Until recently, i-motifs were thought to be unstable in physiological cellular environments. Studies demonstrating their existence in the human genome and role in gene regulation are now shining light on their biological relevance. Herein, we review the effects of epigenetic modifications on i-motif structure and stability, and biological factors that affect i-motif formation within cells. Furthermore, we highlight recent progress in targeting i-motifs with structure-specific ligands for biotechnology and therapeutic purposes.
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16
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Gao B, Zheng YT, Su AM, Sun B, Xi XG, Hou XM. Remodeling the conformational dynamics of I-motif DNA by helicases in ATP-independent mode at acidic environment. iScience 2022; 25:103575. [PMID: 34988409 PMCID: PMC8704484 DOI: 10.1016/j.isci.2021.103575] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 10/09/2021] [Accepted: 12/03/2021] [Indexed: 01/18/2023] Open
Abstract
I-motifs are noncanonical four-stranded DNA structures formed by C-rich sequences at acidic environment with critical biofunctions. The particular pH sensitivity has inspired the development of i-motifs as pH sensors and DNA motors in nanotechnology. However, the folding and regulation mechanisms of i-motifs remain elusive. Here, using single-molecule FRET, we first show that i-motifs are more dynamic than G4s. Impressively, i-motifs display a high diversity of six folding species with slow interconversion. Further results indicate that i-motifs can be linearized by Replication protein A. More importantly, we identified a number of helicases with high specificity to i-motifs at low pH. All these helicases directly act on and efficiently resolve i-motifs into intermediates independent of ATP, although they poorly unwind G4 or duplex at low pH. Owing to the extreme sensitivity to helicases and no need for ATP, i-motif may be applied as a probe for helicase sensing both in vitro and in vivo.
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Affiliation(s)
- Bo Gao
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling 712100, China
| | - Ya-Ting Zheng
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling 712100, China
| | - Ai-Min Su
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling 712100, China
| | - Bo Sun
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Xu-Guang Xi
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling 712100, China
- LBPA, Ecole Normale Supérieure Paris-Saclay, CNRS, Gif-sur-Yvette, France
| | - Xi-Miao Hou
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling 712100, China
- Corresponding author
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17
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Kretzmann JA, Irving KL, Smith NM, Evans CW. Modulating gene expression in breast cancer via DNA secondary structure and the CRISPR toolbox. NAR Cancer 2022; 3:zcab048. [PMID: 34988459 PMCID: PMC8693572 DOI: 10.1093/narcan/zcab048] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 11/26/2021] [Accepted: 12/01/2021] [Indexed: 12/11/2022] Open
Abstract
Breast cancer is the most commonly diagnosed malignancy in women, and while the survival prognosis of patients with early-stage, non-metastatic disease is ∼75%, recurrence poses a significant risk and advanced and/or metastatic breast cancer is incurable. A distinctive feature of advanced breast cancer is an unstable genome and altered gene expression patterns that result in disease heterogeneity. Transcription factors represent a unique therapeutic opportunity in breast cancer, since they are known regulators of gene expression, including gene expression involved in differentiation and cell death, which are themselves often mutated or dysregulated in cancer. While transcription factors have traditionally been viewed as 'undruggable', progress has been made in the development of small-molecule therapeutics to target relevant protein-protein, protein-DNA and enzymatic active sites, with varying levels of success. However, non-traditional approaches such as epigenetic editing, transcriptional control via CRISPR/dCas9 systems, and gene regulation through non-canonical nucleic acid secondary structures represent new directions yet to be fully explored. Here, we discuss these new approaches and current limitations in light of new therapeutic opportunities for breast cancers.
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Affiliation(s)
- Jessica A Kretzmann
- Laboratory for Biomolecular Nanotechnology, Department of Physics, Technical University of Munich, Am Coulombwall 4a, 85748 Garching, Germany
| | - Kelly L Irving
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia
| | - Nicole M Smith
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia
| | - Cameron W Evans
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia
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18
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Grün JT, Schwalbe H. Folding dynamics of polymorphic G-quadruplex structures. Biopolymers 2021; 113:e23477. [PMID: 34664713 DOI: 10.1002/bip.23477] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 09/30/2021] [Accepted: 09/30/2021] [Indexed: 12/14/2022]
Abstract
G-quadruplexes (G4), found in numerous places within the human genome, are involved in essential processes of cell regulation. Chromosomal DNA G4s are involved for example, in replication and transcription as first steps of gene expression. Hence, they influence a plethora of downstream processes. G4s possess an intricate structure that differs from canonical B-form DNA. Identical DNA G4 sequences can adopt multiple long-lived conformations, a phenomenon known as G4 polymorphism. A detailed understanding of the molecular mechanisms that drive G4 folding is essential to understand their ambivalent regulatory roles. Disentangling the inherent dynamic and polymorphic nature of G4 structures thus is key to unravel their biological functions and make them amenable as molecular targets in novel therapeutic approaches. We here review recent experimental approaches to monitor G4 folding and discuss structural aspects for possible folding pathways. Substantial progress in the understanding of G4 folding within the recent years now allows drawing comprehensive models of the complex folding energy landscape of G4s that we herein evaluate based on computational and experimental evidence.
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Affiliation(s)
- J Tassilo Grün
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe-University, Frankfurt/M, Germany.,Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Frankfurt/M, Germany
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19
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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: 23] [Impact Index Per Article: 7.7] [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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20
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Hu C, Jonchhe S, Pokhrel P, Karna D, Mao H. Mechanical unfolding of ensemble biomolecular structures by shear force. Chem Sci 2021; 12:10159-10164. [PMID: 34377405 PMCID: PMC8336480 DOI: 10.1039/d1sc02257a] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 07/11/2021] [Indexed: 01/09/2023] Open
Abstract
Mechanical unfolding of biomolecular structures has been exclusively performed at the single-molecule level by single-molecule force spectroscopy (SMFS) techniques. Here we transformed sophisticated mechanical investigations on individual molecules into a simple platform suitable for molecular ensembles. By using shear flow inside a homogenizer tip, DNA secondary structures such as i-motifs are unfolded by shear force up to 50 pN at a 77 796 s-1 shear rate. We found that the larger the molecules, the higher the exerted shear forces. This shear force approach revealed affinity between ligands and i-motif structures. It also demonstrated a mechano-click reaction in which a Cu(i) catalyzed azide-alkyne cycloaddition was modulated by shear force. We anticipate that this ensemble force spectroscopy method can investigate intra- and inter-molecular interactions with the throughput, accuracy, and robustness unparalleled to those of SMFS methods.
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Affiliation(s)
- Changpeng Hu
- Department of Chemistry & Biochemistry and School of Biomedical Sciences, Advanced Materials and Liquid Crystal Institute, Kent State University Kent OH 44242 USA
| | - Sagun Jonchhe
- Department of Chemistry & Biochemistry and School of Biomedical Sciences, Advanced Materials and Liquid Crystal Institute, Kent State University Kent OH 44242 USA
| | - Pravin Pokhrel
- Department of Chemistry & Biochemistry and School of Biomedical Sciences, Advanced Materials and Liquid Crystal Institute, Kent State University Kent OH 44242 USA
| | - Deepak Karna
- Department of Chemistry & Biochemistry and School of Biomedical Sciences, Advanced Materials and Liquid Crystal Institute, Kent State University Kent OH 44242 USA
| | - Hanbin Mao
- Department of Chemistry & Biochemistry and School of Biomedical Sciences, Advanced Materials and Liquid Crystal Institute, Kent State University Kent OH 44242 USA
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21
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Xi D, Cui M, Zhou X, Zhuge X, Ge Y, Wang Y, Zhang S. Nanopore-Based Single-Molecule Investigation of DNA Sequences with Potential to Form i-Motif Structures. ACS Sens 2021; 6:2691-2699. [PMID: 34237940 DOI: 10.1021/acssensors.1c00712] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
i-Motifs are DNA secondary structures present in cytosine-rich sequences. These structures are formed in regulatory regions of the human genome and play key regulatory roles. The investigation of sequences capable of forming i-motif structures at the single-molecule level is highly important. In this study, we used α-hemolysin nanopores to systematically study a series of DNA sequences at the nanometer scale by providing structure-dependent signature current signals to gain in-sights into the i-motif DNA sequence and structural stability. Increasing the length of the cytosine tract in a range of 3-10 nucleobases resulted in a longer translocation time through the pore, indicating improved stability. Changing the loop sequence and length in the sequences did not affect the formation of the i-motif structure but changed its stability. Importantly, the application of all-atom molecular dynamics simulations revealed the structural morphology of all sequences. Based on these results, we postulated a folding rule for i-motif formation, suggesting that thousands of cytosine-rich sequences in the human genome might fold into i-motif structures. Many of these were found in locations where structure formation is likely to play regulatory roles. These findings provide insights into the application of nanopores as a powerful tool for discovering potential i-motif-forming sequences and lay a foundation for future studies exploring the biological roles of i-motifs.
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Affiliation(s)
- Dongmei Xi
- Shandong Provincial Key Laboratory of Detection Technology for Tumor Markers, College of Life Sciences, Linyi University, Linyi 276005, P. R. China
| | - Mengjie Cui
- Shandong Provincial Key Laboratory of Detection Technology for Tumor Markers, College of Chemistry and Chemical Engineering, Linyi University, Linyi 276005, P. R. China
| | - Xin Zhou
- Shandong Provincial Key Laboratory of Detection Technology for Tumor Markers, College of Chemistry and Chemical Engineering, Linyi University, Linyi 276005, P. R. China
| | - Xiao Zhuge
- Shandong Provincial Key Laboratory of Detection Technology for Tumor Markers, College of Chemistry and Chemical Engineering, Linyi University, Linyi 276005, P. R. China
| | - Yaxian Ge
- Shandong Provincial Key Laboratory of Detection Technology for Tumor Markers, College of Chemistry and Chemical Engineering, Linyi University, Linyi 276005, P. R. China
| | - Ying Wang
- Shandong Provincial Key Laboratory of Detection Technology for Tumor Markers, College of Life Sciences, Linyi University, Linyi 276005, P. R. China
| | - Shusheng Zhang
- Shandong Provincial Key Laboratory of Detection Technology for Tumor Markers, College of Chemistry and Chemical Engineering, Linyi University, Linyi 276005, P. R. China
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22
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Gao B, Hou XM. Opposite Effects of Potassium Ions on the Thermal Stability of i-Motif DNA in Different Buffer Systems. ACS OMEGA 2021; 6:8976-8985. [PMID: 33842768 PMCID: PMC8028132 DOI: 10.1021/acsomega.0c06350] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 03/11/2021] [Indexed: 05/12/2023]
Abstract
i-motifs are noncanonical DNA structures formed via the stack of intercalating hemi-protonated C+: C base pairs in C-rich DNA strands and play essential roles in the regulation of gene expression. Here, we systematically investigated the impacts of K+ on i-motif DNA folding using different buffer systems. We found that i-motif structures display very different T m values at the same pH and ion strength in different buffer systems. More importantly, K+ disrupts the i-motif formed in the MES and Bis-Tris buffer; however, K+ stabilizes the i-motif in phosphate, citrate, and sodium cacodylate buffers. Next, we selected phosphate buffer and confirmed by single-molecule fluorescence resonance energy transfer that K+ indeed has the stabilizing effect on the folding of i-motif DNA from pH 5.8 to 8.0. Nonetheless, circular dichroism spectra further indicate that the structures formed by i-motif sequences at high K+ concentrations at neutral and alkaline pH are not i-motif but other types of higher-order structures and most likely C-hairpins. We finally proposed the mechanisms of how K+ plays the opposite roles in different buffer systems. The present study may provide new insights into our understanding of the formation and stability of i-motif DNA.
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Affiliation(s)
| | - Xi-Miao Hou
- . Phone: +86 29 8708 1664. Fax: +86 29 8708 1664
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23
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Megalathan A, Wijesinghe KM, Ranson L, Dhakal S. Single-Molecule Analysis of Nanocircle-Embedded I-Motifs under Crowding. J Phys Chem B 2021; 125:2193-2201. [PMID: 33629846 DOI: 10.1021/acs.jpcb.0c09640] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cytosine (C)-rich regions of single-stranded DNA or RNA can fold into a tetraplex structure called i-motifs, which are typically stable under acidic pHs due to the need for protons to stabilize C-C interactions. While new studies have shown evidence for the formation of i-motifs at neutral and even physiological pH, it is not clear whether i-motifs can stably form in cells where DNA experiences topological constraint and crowding. Similarly, several studies have shown that a molecularly crowded environment promotes the formation of i-motifs at physiological pH; however, whether the intracellular crowding counteracts the topological destabilization of i-motifs is yet to be investigated. In this manuscript, using fluorescence resonance energy transfer (FRET)-based single-molecule analyses of human telomeric (hTel) i-motifs embedded in nanocircles as a proof-of-concept platform, we investigated the overall effects of crowding and topological constraint on the i-motif behavior. The smFRET analysis of the nanoassembly showed that the i-motif remains folded at pH 5.5 but unfolds at higher pHs. However, in the presence of a crowder (30% PEG 6000), i-motifs are formed at physiological pH overcoming the topological constraint imposed by the DNA nanocircles. Analysis of FRET-time traces show that the hTel sequence primarily assumes the folded state at pH ≤7.0 under crowding, but it undergoes slow conformational transitions between the folded and unfolded states at physiological pH. Our demonstration that the i-motif can form under cell-mimic crowding and topologically constrained environments may provide new insights into the potential biological roles of i-motifs and also into the design and development of i-motif-based biosensors, therapy, and other nanotechnological applications.
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Affiliation(s)
- Anoja Megalathan
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Kalani M Wijesinghe
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Leslie Ranson
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Soma Dhakal
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
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24
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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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25
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Brown SL, Kendrick S. The i-Motif as a Molecular Target: More Than a Complementary DNA Secondary Structure. Pharmaceuticals (Basel) 2021; 14:ph14020096. [PMID: 33513764 PMCID: PMC7911047 DOI: 10.3390/ph14020096] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 01/20/2021] [Accepted: 01/22/2021] [Indexed: 12/25/2022] Open
Abstract
Stretches of cytosine-rich DNA are capable of adopting a dynamic secondary structure, the i-motif. When within promoter regions, the i-motif has the potential to act as a molecular switch for controlling gene expression. However, i-motif structures in genomic areas of repetitive nucleotide sequences may play a role in facilitating or hindering expansion of these DNA elements. Despite research on the i-motif trailing behind the complementary G-quadruplex structure, recent discoveries including the identification of a specific i-motif antibody are pushing this field forward. This perspective reviews initial and current work characterizing the i-motif and providing insight into the biological function of this DNA structure, with a focus on how the i-motif can serve as a molecular target for developing new therapeutic approaches to modulate gene expression and extension of repetitive DNA.
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26
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Xu YZ, Jenjaroenpun P, Wongsurawat T, Byrum SD, Shponka V, Tannahill D, Chavez EA, Hung SS, Steidl C, Balasubramanian S, Rimsza LM, Kendrick S. Activation-induced cytidine deaminase localizes to G-quadruplex motifs at mutation hotspots in lymphoma. NAR Cancer 2020; 2:zcaa029. [PMID: 33094287 PMCID: PMC7556405 DOI: 10.1093/narcan/zcaa029] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 08/31/2020] [Accepted: 09/29/2020] [Indexed: 01/03/2023] Open
Abstract
Diffuse large B-cell lymphoma (DLBCL) is a molecularly heterogeneous group of malignancies with frequent genetic abnormalities. G-quadruplex (G4) DNA structures may facilitate this genomic instability through association with activation-induced cytidine deaminase (AID), an antibody diversification enzyme implicated in mutation of oncogenes in B-cell lymphomas. Chromatin immunoprecipitation sequencing analyses in this study revealed that AID hotspots in both activated B cells and lymphoma cells in vitro were highly enriched for G4 elements. A representative set of these targeted sequences was validated for characteristic, stable G4 structure formation including previously unknown G4s in lymphoma-associated genes, CBFA2T3, SPIB, BCL6, HLA-DRB5 and MEF2C, along with the established BCL2 and MYC structures. Frequent genome-wide G4 formation was also detected for the first time in DLBCL patient-derived tissues using BG4, a structure-specific G4 antibody. Tumors with greater staining were more likely to have concurrent BCL2 and MYC oncogene amplification and BCL2 mutations. Ninety-seven percent of the BCL2 mutations occurred within G4 sites that overlapped with AID binding. G4 localization at sites of mutation, and within aggressive DLBCL tumors harboring amplified BCL2 and MYC, supports a role for G4 structures in events that lead to a loss of genomic integrity, a critical step in B-cell lymphomagenesis.
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Affiliation(s)
- Ying-Zhi Xu
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Piroon Jenjaroenpun
- Department of Bioinformatics, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
- Division of Bioinformatics and Data Management for Research, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
| | - Thidathip Wongsurawat
- Department of Bioinformatics, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
- Division of Bioinformatics and Data Management for Research, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
| | - Stephanie D Byrum
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Volodymyr Shponka
- Department of Pathology, University of Arizona, Tucson, AZ 85721, USA
| | - David Tannahill
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, UK
| | | | - Stacy S Hung
- British Columbia Cancer Agency, Vancouver, BC V5Z 1L3, Canada
| | | | - Shankar Balasubramanian
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, UK
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK
| | - Lisa M Rimsza
- Laboratory Medicine and Pathology, Mayo Clinic, Scottsdale, AZ 85259, USA
| | - Samantha Kendrick
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
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27
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King JJ, Irving KL, Evans CW, Chikhale RV, Becker R, Morris CJ, Peña Martinez CD, Schofield P, Christ D, Hurley LH, Waller ZAE, Iyer KS, Smith NM. DNA G-Quadruplex and i-Motif Structure Formation Is Interdependent in Human Cells. J Am Chem Soc 2020; 142:20600-20604. [PMID: 33253551 DOI: 10.1021/jacs.0c11708] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Guanine- and cytosine-rich nucleic acid sequences have the potential to form secondary structures such as G-quadruplexes and i-motifs, respectively. We show that stabilization of G-quadruplexes using small molecules destabilizes the i-motifs, and vice versa, indicating these gene regulatory controllers are interdependent in human cells. This has important implications as these structures are predominately considered as isolated structural targets for therapy, but their interdependency highlights the interplay of both structures as an important gene regulatory switch.
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Affiliation(s)
- Jessica J King
- School of Molecular Sciences, University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Kelly L Irving
- School of Molecular Sciences, University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Cameron W Evans
- School of Molecular Sciences, University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Rupesh V Chikhale
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K.,UCL School of Pharmacy, 29-39 Brunswick Square, London WC1N 1AX, U.K
| | - Rouven Becker
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Christopher J Morris
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Cristian D Peña Martinez
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Darlinghurst, Sydney New South Wales 2010, Australia
| | - Peter Schofield
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Darlinghurst, Sydney New South Wales 2010, Australia.,St Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Kensington, Sydney, New South Wales 2052, Australia
| | - Daniel Christ
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Darlinghurst, Sydney New South Wales 2010, Australia.,St Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Kensington, Sydney, New South Wales 2052, Australia
| | - Laurence H Hurley
- College of Pharmacy, University of Arizona, 1703 East Mabel Street, Tucson, Arizona 85721, United States
| | - Zoë A E Waller
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K.,UCL School of Pharmacy, 29-39 Brunswick Square, London WC1N 1AX, U.K
| | - K Swaminathan Iyer
- School of Molecular Sciences, University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Nicole M Smith
- School of Molecular Sciences, University of Western Australia, Crawley, Western Australia 6009, Australia
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28
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Sanchez-Martin V, Lopez-Pujante C, Soriano-Rodriguez M, Garcia-Salcedo JA. An Updated Focus on Quadruplex Structures as Potential Therapeutic Targets in Cancer. Int J Mol Sci 2020; 21:ijms21238900. [PMID: 33255335 PMCID: PMC7734589 DOI: 10.3390/ijms21238900] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 11/13/2020] [Accepted: 11/20/2020] [Indexed: 02/06/2023] Open
Abstract
Non-canonical, four-stranded nucleic acids secondary structures are present within regulatory regions in the human genome and transcriptome. To date, these quadruplex structures include both DNA and RNA G-quadruplexes, formed in guanine-rich sequences, and i-Motifs, found in cytosine-rich sequences, as their counterparts. Quadruplexes have been extensively associated with cancer, playing an important role in telomere maintenance and control of genetic expression of several oncogenes and tumor suppressors. Therefore, quadruplex structures are considered attractive molecular targets for cancer therapeutics with novel mechanisms of action. In this review, we provide a general overview about recent research on the implications of quadruplex structures in cancer, firstly gathering together DNA G-quadruplexes, RNA G-quadruplexes as well as DNA i-Motifs.
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Affiliation(s)
- Victoria Sanchez-Martin
- GENYO, Centre for Genomics and Oncological Research, Pfizer/University of Granada/Andalusian Regional Government, PTS Granada, 18016 Granada, Spain; (V.S.-M.); (C.L.-P.)
- Microbiology Unit, University Hospital Virgen de las Nieves, Biosanitary Research Institute IBS, Granada, 18014 Granada, Spain
- Department of Biochemistry, Molecular Biology III and Immunology, University of Granada, 18016 Granada, Spain
| | - Carmen Lopez-Pujante
- GENYO, Centre for Genomics and Oncological Research, Pfizer/University of Granada/Andalusian Regional Government, PTS Granada, 18016 Granada, Spain; (V.S.-M.); (C.L.-P.)
| | - Miguel Soriano-Rodriguez
- GENYO, Centre for Genomics and Oncological Research, Pfizer/University of Granada/Andalusian Regional Government, PTS Granada, 18016 Granada, Spain; (V.S.-M.); (C.L.-P.)
- Centre for Intensive Mediterranean Agrosystems and Agri-food Biotechnology (CIAMBITAL), University of Almeria, 04001 Almeria, Spain
- Correspondence: (M.S.-R.); (J.A.G.-S.); Tel.: +34-958715500 (M.S.-R.); +34-958715500 (J.A.G.-S.)
| | - Jose A. Garcia-Salcedo
- GENYO, Centre for Genomics and Oncological Research, Pfizer/University of Granada/Andalusian Regional Government, PTS Granada, 18016 Granada, Spain; (V.S.-M.); (C.L.-P.)
- Microbiology Unit, University Hospital Virgen de las Nieves, Biosanitary Research Institute IBS, Granada, 18014 Granada, Spain
- Correspondence: (M.S.-R.); (J.A.G.-S.); Tel.: +34-958715500 (M.S.-R.); +34-958715500 (J.A.G.-S.)
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29
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Zhang X, Zhang Y, Zhang W. Dynamic topology of double-stranded telomeric DNA studied by single-molecule manipulation in vitro. Nucleic Acids Res 2020; 48:6458-6470. [PMID: 32496520 PMCID: PMC7337930 DOI: 10.1093/nar/gkaa479] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 05/17/2020] [Accepted: 05/27/2020] [Indexed: 12/18/2022] Open
Abstract
The dynamic topological structure of telomeric DNA is closely related to its biological function; however, no such structural information on full-length telomeric DNA has been reported due to difficulties synthesizing long double-stranded telomeric DNA. Herein, we developed an EM-PCR and TA cloning-based approach to synthesize long-chain double-stranded tandem repeats of telomeric DNA. Using mechanical manipulation assays based on single-molecule atomic force microscopy, we found that mechanical force can trigger the melting of double-stranded telomeric DNA and the formation of higher-order structures (G-quadruplexes or i-motifs). Our results show that only when both the G-strand and C-strand of double-stranded telomeric DNA form higher-order structures (G-quadruplexes or i-motifs) at the same time (e.g. in the presence of 100 mM KCl under pH 4.7), that the higher-order structure(s) can remain after the external force is removed. The presence of monovalent K+, single-wall carbon nanotubes (SWCNTs), acidic conditions, or short G-rich fragments (∼30 nt) can shift the transition from dsDNA to higher-order structures. Our results provide a new way to regulate the topology of telomeric DNA.
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Affiliation(s)
- Xiaonong Zhang
- State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, People's Republic of China
| | - Yingqi Zhang
- State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, People's Republic of China
| | - Wenke Zhang
- State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, People's Republic of China
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30
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Varshney D, Spiegel J, Zyner K, Tannahill D, Balasubramanian S. The regulation and functions of DNA and RNA G-quadruplexes. Nat Rev Mol Cell Biol 2020; 21:459-474. [PMID: 32313204 PMCID: PMC7115845 DOI: 10.1038/s41580-020-0236-x] [Citation(s) in RCA: 583] [Impact Index Per Article: 145.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/11/2020] [Indexed: 02/06/2023]
Abstract
DNA and RNA can adopt various secondary structures. Four-stranded G-quadruplex (G4) structures form through self-recognition of guanines into stacked tetrads, and considerable biophysical and structural evidence exists for G4 formation in vitro. Computational studies and sequencing methods have revealed the prevalence of G4 sequence motifs at gene regulatory regions in various genomes, including in humans. Experiments using chemical, molecular and cell biology methods have demonstrated that G4s exist in chromatin DNA and in RNA, and have linked G4 formation with key biological processes ranging from transcription and translation to genome instability and cancer. In this Review, we first discuss the identification of G4s and evidence for their formation in cells using chemical biology, imaging and genomic technologies. We then discuss possible functions of DNA G4s and their interacting proteins, particularly in transcription, telomere biology and genome instability. Roles of RNA G4s in RNA biology, especially in translation, are also discussed. Furthermore, we consider the emerging relationships of G4s with chromatin and with RNA modifications. Finally, we discuss the connection between G4 formation and synthetic lethality in cancer cells, and recent progress towards considering G4s as therapeutic targets in human diseases.
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Affiliation(s)
- Dhaval Varshney
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, Cambridge, UK
| | - Jochen Spiegel
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, Cambridge, UK
| | - Katherine Zyner
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, Cambridge, UK
| | - David Tannahill
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, Cambridge, UK
| | - Shankar Balasubramanian
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, Cambridge, UK.
- Department of Chemistry, University of Cambridge, Cambridge, UK.
- School of Clinical Medicine, University of Cambridge, Cambridge, UK.
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31
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Jonchhe S, Pandey S, Karna D, Pokhrel P, Cui Y, Mishra S, Sugiyama H, Endo M, Mao H. Duplex DNA Is Weakened in Nanoconfinement. J Am Chem Soc 2020; 142:10042-10049. [PMID: 32383870 PMCID: PMC7295077 DOI: 10.1021/jacs.0c01978] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
For proteins and DNA secondary structures such as G-quadruplexes and i-motifs, nanoconfinement can facilitate their folding and increase structural stabilities. However, the properties of the physiologically prevalent B-DNA duplex have not been elucidated inside the nanocavity. Using a 17-bp DNA duplex in the form of a hairpin stem, here, we probed folding and unfolding transitions of the hairpin DNA duplex inside a DNA origami nanocavity. Compared to the free solution, the DNA hairpin inside the nanocage with a 15 × 15 nm cross section showed a drastic decrease in mechanical (20 → 9 pN) and thermodynamic (25 → 6 kcal/mol) stabilities. Free energy profiles revealed that the activation energy of unzipping the hairpin DNA duplex decreased dramatically (28 → 8 kcal/mol), whereas the transition state moved closer to the unfolded state inside the nanocage. All of these indicate that nanoconfinement weakens the stability of the hairpin DNA duplex to an unexpected extent. In a DNA hairpin made of a stem that contains complementary telomeric G-quadruplex (GQ) and i-motif (iM) forming sequences, formation of the Hoogsteen base pairs underlining the GQ or iM is preferred over the Watson-Crick base pairs in the DNA hairpin. These results shed light on the behavior of DNA in nanochannels, nanopores, or nanopockets of various natural or synthetic machineries. It also elucidates an alternative pathway to populate noncanonical DNA over B-DNA in the cellular environment where the nanocavity is abundant.
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Affiliation(s)
- Sagun Jonchhe
- Department of Chemistry & Biochemistry, Kent State University, Kent, OH 44242, USA
| | - Shankar Pandey
- Department of Chemistry & Biochemistry, Kent State University, Kent, OH 44242, USA
| | - Deepak Karna
- Department of Chemistry & Biochemistry, Kent State University, Kent, OH 44242, USA
| | - Pravin Pokhrel
- Department of Chemistry & Biochemistry, Kent State University, Kent, OH 44242, USA
| | - Yunxi Cui
- Department of Chemistry & Biochemistry, Kent State University, Kent, OH 44242, USA
| | - Shubham Mishra
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan
- Institute for Integrated Cell–Material Sciences, Kyoto University, Sakyo, Kyoto 606-8501, Japan
| | - Hiroshi Sugiyama
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan
- Institute for Integrated Cell–Material Sciences, Kyoto University, Sakyo, Kyoto 606-8501, Japan
| | - Masayuki Endo
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan
- Institute for Integrated Cell–Material Sciences, Kyoto University, Sakyo, Kyoto 606-8501, Japan
| | - Hanbin Mao
- Department of Chemistry & Biochemistry, Kent State University, Kent, OH 44242, USA
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32
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Carbon Nanotubes and Short Cytosine-Rich Telomeric DNA Oligomeres as Platforms for Controlled Release of Doxorubicin-A Molecular Dynamics Study. Int J Mol Sci 2020; 21:ijms21103619. [PMID: 32443891 PMCID: PMC7279147 DOI: 10.3390/ijms21103619] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 05/14/2020] [Accepted: 05/18/2020] [Indexed: 02/07/2023] Open
Abstract
This work deals with molecular dynamics analysis of properties of systems composed of carbon nanotubes and short telomeric DNA strands able to fold into i-motif structures at slightly acidic pH conditions. The studies are focused on possible application of such constructs as pH-controlled drug delivery and release systems. We study two different approaches. The first assumes that folding/unfolding property of these DNA strands might realize a gate closing/opening mechanism with carbon nanotube as a container for drug molecules. The second approach assumes that these DNA strands can modulate the drug intercalating property as a function of pH. As a model drug molecule we used doxorubicin. We found that the first approach is impossible to realize because doxorubicin is not effectively locked in the nanotube interior by DNA oligonuceotides. The second approach is more promising though direct drug release was not observed in unbiased molecular dynamics simulations. However, by applying detailed analysis of pair interaction energies, mobilities and potential of mean force we can show that doxorubicin can be released when the DNA strands fold into i-motifs. Carbon nanotube in that latter case acts mainly as a carrier for active phase which is composed of DNA fragments able to fold into noncanonical tetraplexes (i-motif).
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33
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Navarro A, Benabou S, Eritja R, Gargallo R. Influence of pH and a porphyrin ligand on the stability of a G-quadruplex structure within a duplex segment near the promoter region of the SMARCA4 gene. Int J Biol Macromol 2020; 159:383-393. [PMID: 32416304 DOI: 10.1016/j.ijbiomac.2020.05.062] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 04/06/2020] [Accepted: 05/09/2020] [Indexed: 12/20/2022]
Abstract
In a previous work, the formation of G-quadruplex structures in a 44-nucleotide long sequence found near the promoter region of the SMARCA4 gene was reported. The central 25 nucleotides were able to fold into an antiparallel G-quadruplex structure, the stability of which was pH-dependent. In the present work, the effect of the presence of lateral nucleotides and the complementary cytosine-rich strand on the stability of this G-quadruplex has been characterized. Moreover, the role of the model ligand TMPyP4 has been studied. Spectroscopic and separation techniques, as well as multivariate data analysis methods, have been used with these purposes. The results have shown that stability of the G-quadruplex as a function of pH or temperature is greatly reduced in the presence of the lateral nucleotides. The influence of the complementary strand does not prevent the formation of the G-quadruplex. Moreover, attempts to modulate the equilibria by an external ligand led us to determine the influence of the TMPyP4 porphyrin on these complex equilibria. This study could eventually help to understand the regulation of SMARCA4 expression.
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Affiliation(s)
- Alba Navarro
- Department of Chemical Engineering and Analytical Chemistry, University of Barcelona, Spain
| | - Sanae Benabou
- Department of Chemical Engineering and Analytical Chemistry, University of Barcelona, Spain; Université de Bordeaux, CNRS, Inserm, Laboratoire Acides Nucléiques: Régulations Naturelle et Artificielle (ARNA, U1212, UMR5320), IECB, 2 rue Robert Escarpit, 33600 Pessac, France
| | - Ramon Eritja
- Institute for Advanced Chemistry of Catalonia (IQAC), CSIC, Networking Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain
| | - Raimundo Gargallo
- Department of Chemical Engineering and Analytical Chemistry, University of Barcelona, Spain.
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34
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Panczyk T, Wojton P, Wolski P. Molecular Dynamics Study of the Interaction of Carbon Nanotubes With Telomeric DNA Fragment Containing Noncanonical G-quadruplex and i-Motif Forms. Int J Mol Sci 2020; 21:ijms21061925. [PMID: 32168928 PMCID: PMC7139311 DOI: 10.3390/ijms21061925] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 03/10/2020] [Accepted: 03/10/2020] [Indexed: 12/22/2022] Open
Abstract
This work deals with molecular dynamics simulations of systems composed of telomeric dsDNA fragments, iG, and functionalized carbon nanotubes, fCNT. The iG contains 90 nucleotides in total and in its middle part the noncanonical i-motif and G-quadruplex are formed. Two chiralities of the fCNT were used, i.e., (10,0) and (20,0) and these nanotubes were either on-tip functionalized by guanine containing functional groups or left without functionalization. We proposed a dedicated computational procedure, based on the replica exchange concept, for finding a thermodynamically optimal conformation of iG and fCNT without destroying the very fragile noncanonical parts of the iG. We found that iG forms a V-shape spatial structure with the noncanonical fragments located at the edge and the remaining dsDNA strands forming the arms of V letter. The optimal configuration of iG in reference to fCNT strongly depends on the on-tip functionalization of the fCNT. The carbon nanotube without functionalization moves freely between the dsDNA arms, while the presence of guanine residues leads to immobilization of the fCNT and preferential location of the nanotube tip near the junction between the dsDNA duplex and i-motif and G-quadruplex. We also studied how the presence of fCNT affects the stability of the i-motif at the neutral pH when the cytosine pairs are nonprotonated. We concluded that carbon nanotubes do not improve the stability of the spatial structure of i-motif also when it is a part of a bigger structure like the iG. Such an effect was described in literature in reference to carboxylated nanotubes. Our current results suggest that the stabilization of i-motif is most probably related to easy formation of semiprotonated cytosine pairs at neutral pH due to interaction with carboxylated carbon nanotubes.
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35
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Amparo C, Clark J, Bedell V, Murata-Collins JL, Martella M, Pichiorri F, Warner EF, Abdelhamid MAS, Waller ZAE, Smith SS. Duplex DNA from Sites of Helicase-Polymerase Uncoupling Links Non-B DNA Structure Formation to Replicative Stress. Cancer Genomics Proteomics 2020; 17:101-115. [PMID: 32108033 DOI: 10.21873/cgp.20171] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 01/25/2020] [Accepted: 01/27/2020] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Replication impediments can produce helicase-polymerase uncoupling allowing lagging strand synthesis to continue for as much as 6 kb from the site of the impediment. MATERIALS AND METHODS We developed a cloning procedure designed to recover fragments from lagging strand near the helicase halt site. RESULTS A total of 62% of clones from a p53-deficient tumor cell line (PC3) and 33% of the clones from a primary cell line (HPS-19I) were within 5 kb of a G-quadruplex forming sequence. Analyses of a RACK7 gene sequence, that was cloned multiple times from the PC3 line, revealed multiple deletions in region about 1 kb from the cloned region that was present in a non-B conformation. Sequences from the region formed G-quadruplex and i-motif structures under physiological conditions. CONCLUSION Defects in components of non-B structure suppression systems (e.g. p53 helicase targeting) promote replication-linked damage selectively targeted to sequences prone to G-quadruplex and i-motif formation.
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Affiliation(s)
- Camille Amparo
- Division of Urology, City of Hope National Medical Center, Duarte, CA, U.S.A.,Beckman Research Institute, City of Hope, Duarte, CA, U.S.A
| | - Jarrod Clark
- Division of Urology, City of Hope National Medical Center, Duarte, CA, U.S.A.,Beckman Research Institute, City of Hope, Duarte, CA, U.S.A
| | - Victoria Bedell
- Division of Cytogenetics, City of Hope National Medical Center, Duarte, CA, U.S.A
| | | | - Marianna Martella
- Judy and Bernard Briskin Center for Multiple Myeloma Research, City of Hope National Medical Center, Duarte, CA, U.S.A.,Hematological Malignancies and Translational Science, City of Hope National Medical Center, Duarte, CA, U.S.A
| | - Flavia Pichiorri
- Judy and Bernard Briskin Center for Multiple Myeloma Research, City of Hope National Medical Center, Duarte, CA, U.S.A.,Hematological Malignancies and Translational Science, City of Hope National Medical Center, Duarte, CA, U.S.A
| | - Emily F Warner
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich, U.K
| | | | - Zoë A E Waller
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich, U.K
| | - Steven S Smith
- Beckman Research Institute, City of Hope, Duarte, CA, U.S.A. .,Hematological Malignancies and Translational Science, City of Hope National Medical Center, Duarte, CA, U.S.A
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36
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Abstract
Guanine-rich DNA sequences can fold into four-stranded, noncanonical secondary structures called G-quadruplexes (G4s). G4s were initially considered a structural curiosity, but recent evidence suggests their involvement in key genome functions such as transcription, replication, genome stability, and epigenetic regulation, together with numerous connections to cancer biology. Collectively, these advances have stimulated research probing G4 mechanisms and consequent opportunities for therapeutic intervention. Here, we provide a perspective on the structure and function of G4s with an emphasis on key molecules and methodological advances that enable the study of G4 structures in human cells. We also critically examine recent mechanistic insights into G4 biology and protein interaction partners and highlight opportunities for drug discovery.
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Affiliation(s)
- Jochen Spiegel
- Cancer Research UK, Cambridge Institute, Li Ka Shing Centre, Cambridge CB2 0RE, UK
| | - Santosh Adhikari
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK
| | - Shankar Balasubramanian
- Cancer Research UK, Cambridge Institute, Li Ka Shing Centre, Cambridge CB2 0RE, UK
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK
- School of Clinical Medicine, University of Cambridge, Cambridge CB2 0SP, UK
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37
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Nieuwenhuis M, van de Peppel LJJ, Bakker FT, Zwaan BJ, Aanen DK. Enrichment of G4DNA and a Large Inverted Repeat Coincide in the Mitochondrial Genomes of Termitomyces. Genome Biol Evol 2020; 11:1857-1869. [PMID: 31209489 PMCID: PMC6609731 DOI: 10.1093/gbe/evz122] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/11/2019] [Indexed: 12/20/2022] Open
Abstract
Mitochondria retain their own genome, a hallmark of their bacterial ancestry. Mitochondrial genomes (mtDNA) are highly diverse in size, shape, and structure, despite their conserved function across most eukaryotes. Exploring extreme cases of mtDNA architecture can yield important information on fundamental aspects of genome biology. We discovered that the mitochondrial genomes of a basidiomycete fungus (Termitomyces spp.) contain an inverted repeat (IR), a duplicated region half the size of the complete genome. In addition, we found an abundance of sequences capable of forming G-quadruplexes (G4DNA); structures that can disrupt the double helical formation of DNA. G4DNA is implicated in replication fork stalling, double-stranded breaks, altered gene expression, recombination, and other effects. To determine whether this occurrence of IR and G4DNA was correlated within the genus Termitomyces, we reconstructed the mitochondrial genomes of 11 additional species including representatives of several closely related genera. We show that the mtDNA of all sampled species of Termitomyces and its sister group, represented by the species Tephrocybe rancida and Blastosporella zonata, are characterized by a large IR and enrichment of G4DNA. To determine whether high mitochondrial G4DNA content is common in fungi, we conducted the first broad survey of G4DNA content in fungal mtDNA, revealing it to be a highly variable trait. The results of this study provide important direction for future research on the function and evolution of G4DNA and organellar IRs.
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Affiliation(s)
| | | | - Freek T Bakker
- Biosystematics Group, Wageningen University & Research, The Netherlands
| | - Bas J Zwaan
- Laboratory of Genetics, Wageningen University & Research, The Netherlands
| | - Duur K Aanen
- Laboratory of Genetics, Wageningen University & Research, The Netherlands
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38
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Liu L, Ma C, Wells JW, Chalikian TV. Conformational Preferences of DNA Strands from the Promoter Region of the c-MYC Oncogene. J Phys Chem B 2020; 124:751-762. [PMID: 31923361 DOI: 10.1021/acs.jpcb.9b10518] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We characterized the conformational preferences of DNA in an equimolar mixture of complementary G-rich and C-rich strands from the promoter region of the c-MYC oncogene. Our CD-based approach presupposes that the CD spectrum of such a mixture is the spectral sum of the constituent duplex, G-quadruplex, i-motif, and coiled conformations. Spectra were acquired over a range of temperatures at different pHs and concentrations of KCl. Each spectrum was unmixed in terms of the predetermined spectra of the constituent conformational states to obtain the corresponding weighting factors for their fractional contributions to the total population of DNA. The temperature dependences of those contributions then were analyzed in concert according to a model based on a thermodynamic representation of the underlying equilibria. Fitted estimates of the melting enthalpy and temperature obtained for the duplex, G-quadruplex, and i-motif imply that the driving force behind dissociation of the duplex and the concomitant formation of tetrahelical structures is the folding of the G-strand into the G-quadruplex. The liberated C-strand adopts the i-motif conformation at acidic pH and exists in the coiled state at neutral pH. The i-motif alone cannot induce dissociation of the duplex even at pH 5.0, at which it is most stable. Under the physiological conditions of neutral pH, elevated potassium, and room temperature, the duplex and G-quadruplex conformations coexist with the C-strand in the coiled state. Taken together, our results suggest a novel, thermodynamically controlled mechanism for the regulation of gene expression.
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Affiliation(s)
- Lutan Liu
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy , University of Toronto , 144 College Street , Toronto , Ontario M5S 3M2 , Canada
| | - Congshan Ma
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy , University of Toronto , 144 College Street , Toronto , Ontario M5S 3M2 , Canada
| | - James W Wells
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy , University of Toronto , 144 College Street , Toronto , Ontario M5S 3M2 , Canada
| | - Tigran V Chalikian
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy , University of Toronto , 144 College Street , Toronto , Ontario M5S 3M2 , Canada
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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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Chaudhary S, Kaushik M, Ahmed S, Kukreti S. Exploring potential of i-motif DNA formed in the promoter region of GRIN1 gene for nanotechnological applications. RESULTS IN CHEMISTRY 2020. [DOI: 10.1016/j.rechem.2020.100086] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
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41
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Megalathan A, Cox BD, Wilkerson PD, Kaur A, Sapkota K, Reiner JE, Dhakal S. Single-molecule analysis of i-motif within self-assembled DNA duplexes and nanocircles. Nucleic Acids Res 2019; 47:7199-7212. [PMID: 31287873 PMCID: PMC6698746 DOI: 10.1093/nar/gkz565] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 06/13/2019] [Accepted: 07/04/2019] [Indexed: 12/20/2022] Open
Abstract
The cytosine (C)-rich sequences that can fold into tetraplex structures known as i-motif are prevalent in genomic DNA. Recent studies of i-motif-forming sequences have shown increasing evidence of their roles in gene regulation. However, most of these studies have been performed in short single-stranded oligonucleotides, far from the intracellular environment. In cells, i-motif-forming sequences are flanked by DNA duplexes and packed in the genome. Therefore, exploring the conformational dynamics and kinetics of i-motif under such topologically constrained environments is highly relevant in predicting their biological roles. Using single-molecule fluorescence analysis of self-assembled DNA duplexes and nanocircles, we show that the topological environments play a key role on i-motif stability and dynamics. While the human telomere sequence (C3TAA)3C3 assumes i-motif structure at pH 5.5 regardless of topological constraint, it undergoes conformational dynamics among unfolded, partially folded and fully folded states at pH 6.5. The lifetimes of i-motif and the partially folded state at pH 6.5 were determined to be 6 ± 2 and 31 ± 11 s, respectively. Consistent with the partially folded state observed in fluorescence analysis, interrogation of current versus time traces obtained from nanopore analysis at pH 6.5 shows long-lived shallow blockades with a mean lifetime of 25 ± 6 s. Such lifetimes are sufficient for the i-motif and partially folded states to interact with proteins to modulate cellular processes.
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Affiliation(s)
- Anoja Megalathan
- Department of Chemistry, Virginia Commonwealth University, 1001 West Main Street, Richmond, VA 23284, USA
| | - Bobby D Cox
- Department of Physics, Virginia Commonwealth University, 701 West Grace Street, Richmond, VA 23284, USA
| | - Peter D Wilkerson
- Department of Physics, Virginia Commonwealth University, 701 West Grace Street, Richmond, VA 23284, USA
| | - Anisa Kaur
- Department of Chemistry, Virginia Commonwealth University, 1001 West Main Street, Richmond, VA 23284, USA
| | - Kumar Sapkota
- Department of Chemistry, Virginia Commonwealth University, 1001 West Main Street, Richmond, VA 23284, USA
| | - Joseph E Reiner
- Department of Physics, Virginia Commonwealth University, 701 West Grace Street, Richmond, VA 23284, USA
| | - Soma Dhakal
- Department of Chemistry, Virginia Commonwealth University, 1001 West Main Street, Richmond, VA 23284, USA
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42
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Dhamodharan V, Pradeepkumar PI. Specific Recognition of Promoter G-Quadruplex DNAs by Small Molecule Ligands and Light-up Probes. ACS Chem Biol 2019; 14:2102-2114. [PMID: 31532996 DOI: 10.1021/acschembio.9b00475] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
G-Quadruplexes (G4s) are four-stranded nucleic acid structures whose underlying G-rich sequences are present across the chromosome and transcriptome. These highly structured elements are known to regulate many key biological functions such as replication, transcription, translation, and genomic stability, thereby providing an additional layer of gene regulation. G4s are structurally dynamic and diverse, and they can fold into numerous topologies. They are potential targets for small molecules, which can modulate their functions. To this end, myriad classes of small molecules have been developed and studied for their ability to bind and stabilize these unique structures. Though many of them can selectively target G4s over duplex DNA, only a few of them can distinguish one G4 topology from others. Design and development of G4-specific ligands are challenging owing to the subtle structural variations among G4 structures. However, screening assays and computational methods have identified a few classes of ligands that preferentially or specifically target the G4 topology of interest over others. This review focuses on the small molecules and fluorescent probes that specifically target human promoter G4s associated with oncogenes. Targeting promoter G4s could circumvent the issues such as undruggability and development of drug resistance associated with the protein targets. The ligands discussed here highlight that development of G4-specific ligands is an achievable goal in spite of the limited structural data available. The future goal is to pursue the development of G4-specific ligands endowed with drug-like properties for G4-based therapeutics and diagnostics.
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Affiliation(s)
- V. Dhamodharan
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
- Okinawa Institute of Science and Technology Graduate University, Okinawa 9040495, Japan
| | - P. I. Pradeepkumar
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
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Panczyk T, Wojton P, Wolski P. Mechanism of unfolding and relative stabilities of G-quadruplex and I-motif noncanonical DNA structures analyzed in biased molecular dynamics simulations. Biophys Chem 2019; 250:106173. [DOI: 10.1016/j.bpc.2019.106173] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 04/12/2019] [Accepted: 04/12/2019] [Indexed: 12/01/2022]
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44
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Abou Assi H, Garavís M, González C, Damha MJ. i-Motif DNA: structural features and significance to cell biology. Nucleic Acids Res 2019; 46:8038-8056. [PMID: 30124962 PMCID: PMC6144788 DOI: 10.1093/nar/gky735] [Citation(s) in RCA: 233] [Impact Index Per Article: 46.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 08/13/2018] [Indexed: 12/20/2022] Open
Abstract
The i-motif represents a paradigmatic example of the wide structural versatility of nucleic acids. In remarkable contrast to duplex DNA, i-motifs are four-stranded DNA structures held together by hemi- protonated and intercalated cytosine base pairs (C:C+). First observed 25 years ago, and considered by many as a mere structural oddity, interest in and discussion on the biological role of i-motifs have grown dramatically in recent years. In this review we focus on structural aspects of i-motif formation, the factors leading to its stabilization and recent studies describing the possible role of i-motifs in fundamental biological processes.
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Affiliation(s)
- Hala Abou Assi
- Department of Chemistry, McGill University, Montreal, QC H3A 0B8, Canada
| | - Miguel Garavís
- Instituto de Química Física 'Rocasolano', CSIC, C/Serrano 119, 28006 Madrid, Spain
| | - Carlos González
- Instituto de Química Física 'Rocasolano', CSIC, C/Serrano 119, 28006 Madrid, Spain
| | - Masad J Damha
- Department of Chemistry, McGill University, Montreal, QC H3A 0B8, Canada
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45
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Lepper CP, Williams MAK, Edwards PJB, Filichev VV, Jameson GB. Effects of Pressure and pH on the Physical Stability of an I‐Motif DNA Structure. Chemphyschem 2019; 20:1567-1571. [DOI: 10.1002/cphc.201900145] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 05/01/2019] [Indexed: 12/21/2022]
Affiliation(s)
| | - Martin A. K. Williams
- School of Fundamental Sciences The MacDiarmid Institute and the Riddet InstituteMassey University Palmerston North New Zealand
| | | | | | - Geoffrey B. Jameson
- School of Fundamental Sciences The MacDiarmid Institute and the Riddet InstituteMassey University Palmerston North New Zealand
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Sengupta P, Bhattacharya A, Sa G, Das T, Chatterjee S. Truncated G-Quadruplex Isomers Cross-Talk with the Transcription Factors To Maintain Homeostatic Equilibria in c-MYC Transcription. Biochemistry 2019; 58:1975-1991. [PMID: 30920805 DOI: 10.1021/acs.biochem.9b00030] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The nuclease hypersensitive element III1 (NHE III1) upstream c-MYC promoter harbors a transcription-silencing G-quadruplex (Pu27) element. Dynamic turnover of various transcription factors (TFs) across Pu27 to control c-MYC transcription homeostasis is enigmatic. Here, we reveal that native Pu27 evolves truncated G-quadruplex isomers (Pu19, Pu22, Pu24, and Pu25) in cells that are optimal intracellular targets of specific TFs in a sequence- and structure-dependent manner. Nuclear magnetic resonance and isothermal titration calorimetry envisaged that NM23-H2 (nucleoside diphosphate kinase) and nucleolin induce conformational fluctuations in Pu27 to sample specific conformationally restricted conformer(s). Structural investigations revealed that the flanking guanines at 5'-Pu27 control solvent exposure at G-quartets upon NM23-H2 and nucleolin binding driving Pu27 unfolding and folding, respectively. Transient chromatin immunoprecipitations confirmed that NM23-H2 drives the conformation switch to Pu24 that outcompetes nucleolin recruitment. Similarly, nucleolin arrests Pu27 in the Pu22 conformer minimizing NM23-H2 binding at Pu27. hnRNPK (heterogeneous nuclear ribonucleoprotein K) positively regulates NM23-H2 and nucleolin association at Pu27 despite their antagonism. On the basis of these results, we simulated the transcription kinetics in a feed-forward loop in which the transcription output responds to hnRNPK-induced early activation via NM23-H2 association, which favors Pu24 formation at NHE III1 reducing nucleolin occupancy and driving quadruplex unfolding to initiate transcription. NM23-H2 further promotes hnRNPK deposition across NHE III1 altering Pu27 plasticity that finally enriches the nucleolin abundance to drive Pu22 formation and weaken NM23-H2 binding to extinguish transcription. This mechanism involves three positive feedback loops (NM23-H2-hnRNPK, NM23-H2-CNBP, and hnRNPK-nucleolin) and one negative feedback loop (NM23-H2-nucleolin) controlling optimal turnover and residence time of TFs at Pu27 to homeostatically regulate c-MYC transcription.
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Affiliation(s)
- Pallabi Sengupta
- Department of Biophysics , Bose Institute , P 1/12, C. I. T. Road, Scheme-VIIM , Kolkata 700054 , West Bengal , India
| | - Apoorva Bhattacharya
- Division of Molecular Medicine , Bose Institute , P 1/12, C. I. T. Road, Scheme-VIIM , Kolkata 700054 , West Bengal , India
| | - Gaurisankar Sa
- Division of Molecular Medicine , Bose Institute , P 1/12, C. I. T. Road, Scheme-VIIM , Kolkata 700054 , West Bengal , India
| | - Tanya Das
- Division of Molecular Medicine , Bose Institute , P 1/12, C. I. T. Road, Scheme-VIIM , Kolkata 700054 , West Bengal , India
| | - Subhrangsu Chatterjee
- Department of Biophysics , Bose Institute , P 1/12, C. I. T. Road, Scheme-VIIM , Kolkata 700054 , West Bengal , India
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Umek T, Sollander K, Bergquist H, Wengel J, Lundin KE, Smith CIE, Zain R. Oligonucleotide Binding to Non-B-DNA in MYC. Molecules 2019; 24:E1000. [PMID: 30871121 PMCID: PMC6429085 DOI: 10.3390/molecules24051000] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 02/25/2019] [Accepted: 03/06/2019] [Indexed: 11/16/2022] Open
Abstract
MYC, originally named c-myc, is an oncogene deregulated in many different forms of cancer. Translocation of the MYC gene to an immunoglobulin gene leads to an overexpression and the development of Burkitt's lymphoma (BL). Sporadic BL constitutes one subgroup where one of the translocation sites is located at the 5'-vicinity of the two major MYC promoters P₁ and P₂. A non-B-DNA forming sequence within this region has been reported with the ability to form an intramolecular triplex (H-DNA) or a G-quadruplex. We have examined triplex formation at this site first by using a 17 bp triplex-forming oligonucleotide (TFO) and a double strand DNA (dsDNA) target corresponding to the MYC sequence. An antiparallel purine-motif triplex was detected using electrophoretic mobility shift assay. Furthermore, we probed for H-DNA formation using the BQQ-OP based triplex-specific cleavage assay, which indicated the formation of the structure in the supercoiled plasmid containing the corresponding region of the MYC promoter. Targeting non-B-DNA structures has therapeutic potential; therefore, we investigated their influence on strand-invasion of anti-gene oligonucleotides (ON)s. We show that in vitro, non-B-DNA formation at the vicinity of the ON target site facilitates dsDNA strand-invasion of the anti-gene ONs.
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Affiliation(s)
- Tea Umek
- Department of Laboratory Medicine, Clinical Research Center, Karolinska Institutet, Karolinska University Hospital Huddinge, 141 86 Huddinge, Sweden.
| | - Karin Sollander
- Department of Molecular Biology and Functional Genomics, Stockholm University, 171 65 Stockholm, Sweden.
| | - Helen Bergquist
- Department of Laboratory Medicine, Clinical Research Center, Karolinska Institutet, Karolinska University Hospital Huddinge, 141 86 Huddinge, Sweden.
| | - Jesper Wengel
- Biomolecular Nanoscale Engineerng Center, Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, M5230 Odense, Denmark.
| | - Karin E Lundin
- Department of Laboratory Medicine, Clinical Research Center, Karolinska Institutet, Karolinska University Hospital Huddinge, 141 86 Huddinge, Sweden.
| | - C I Edvard Smith
- Department of Laboratory Medicine, Clinical Research Center, Karolinska Institutet, Karolinska University Hospital Huddinge, 141 86 Huddinge, Sweden.
| | - Rula Zain
- Department of Laboratory Medicine, Clinical Research Center, Karolinska Institutet, Karolinska University Hospital Huddinge, 141 86 Huddinge, Sweden.
- Department of Clinical Genetics, Centre for Rare Diseases, Karolinska University Hospital, SE-171 76 Stockholm, Sweden.
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Sun Y, Ji Y, Wang D, Wang J, Liu D. Stabilization of an intermolecular i-motif by lipid modification of cytosine-oligodeoxynucleotides. Org Biomol Chem 2019; 16:4857-4863. [PMID: 29926887 DOI: 10.1039/c8ob00920a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
This paper describes the stabilization of an intermolecular i-motif by lipophilic modification on the 3'-terminus of oligonucleotides. The hydrophobic aliphatic chain connected at the 3'-terminus of a trinucleotide (dC)3 promoted the formation of an i-motif and significantly enhanced the quadruplex's stability. The impact of lipophilic modification on i-motif's thermal stability was studied by UV-thermal denaturation melting experiments and isothermal titration calorimetry. We found that alkyl chains containing more than 14 carbon atoms could elevate the i-motif structure's stability in a wide range of pH and concentrations.
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Affiliation(s)
- Yawei Sun
- State Key Laboratory of Heavy Oil Processing, College of Chemical Engineering, China University of Petroleum (Huadong), Qingdao, 258000, China.
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Cheng Y, Tang Q, Li Y, Zhang Y, Zhao C, Yan J, You H. Folding/unfolding kinetics of G-quadruplexes upstream of the P1 promoter of the human BCL-2 oncogene. J Biol Chem 2019; 294:5890-5895. [PMID: 30787104 DOI: 10.1074/jbc.ra119.007516] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 02/14/2019] [Indexed: 12/29/2022] Open
Abstract
The G-rich Pu39 region of the P1 promoter of the oncogene BCL-2, an apoptosis regulator, can fold into multiple G-quadruplex (G4) structures. Bcl2-2345 and Bcl2-1245 are two major G4 species forming with high thermal stability and distinct topologies in the Pu39 region, but their folding/unfolding kinetics have not yet been investigated. Here, we used magnetic tweezers to measure the mechanical stability and the folding/unfolding kinetics of the Bcl2-2345 and Bcl2-1245 G4 structures. We report that the hybrid-stranded Bcl2-2345 G4 had a lower mechanical stability than the parallel-stranded Bcl2-1245 G4. We observed that the Bcl2-2345 G4 is a kinetically favored structure, whereas the Bcl2-1245 G4, with a slow unfolding rate, may function as a kinetic barrier for transcription. We also determined that in addition to the Bcl2-2345 and Bcl2-1245 G4s, other stable DNA secondary structures, such as a hybrid-stranded Bcl2-1234 G4, can also form in the Pu39 sequence. The characterization of the folding/unfolding kinetics of specific G4s reported here sheds light on the participation of G4s during gene transcription and provides information for designing G4-targeting small molecules that could modulate BCL-2 gene expression.
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Affiliation(s)
- Yuanlei Cheng
- From the School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan, China
| | - Qingnan Tang
- the Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Yutong Li
- From the School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan, China
| | - Yashuo Zhang
- From the School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan, China
| | - Chuyuan Zhao
- the Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Jie Yan
- the Department of Physics, National University of Singapore, Singapore 117542, Singapore; the Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore
| | - Huijuan You
- From the School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan, China.
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50
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Sabale PM, Tanpure AA, Srivatsan SG. Probing the competition between duplex and G-quadruplex/i-motif structures using a conformation-sensitive fluorescent nucleoside probe. Org Biomol Chem 2019; 16:4141-4150. [PMID: 29781489 PMCID: PMC6086326 DOI: 10.1039/c8ob00646f] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Double-stranded segments of a genome that can potentially form G-quadruplex (GQ) and/or i-motif (iM) structures are considered to be important regulatory elements. Hence, the development of a common probe that can detect GQ and iM structures and also distinguish them from a duplex structure will be highly useful in understanding the propensity of such segments to adopt duplex or non-canonical four-stranded structures. Here, we describe the utility of a conformation-sensitive fluorescent nucleoside analog, which was originally developed as a GQ sensor, in detecting the iM structures of C-rich DNA oligonucleotides (ONs). The analog is based on a 5-(benzofuran-2-yl)uracil scaffold, which when incorporated into C-rich ONs (e.g., telomeric repeats) fluorescently distinguishes an iM from random coil and duplex structures. Steady-state and time-resolved fluorescence techniques enabled the determination of transition pH for the transformation of a random coil to an iM structure. Furthermore, a qualitative understanding on the relative population of duplex and GQ/iM forms under physiological conditions could be gained by correlating the fluorescence, CD and thermal melting data. Taken together, this sensor could provide a general platform to profile double-stranded promoter regions in terms of their ability to adopt four-stranded structures, and also could support approaches to discover functional GQ and iM binders.
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Affiliation(s)
- Pramod M Sabale
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune, Dr. Homi Bhabha Road, Pune 411008, India.
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