1
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Yang B, Guneri D, Yu H, Wright EP, Chen W, Waller ZE, Ding Y. Prediction of DNA i-motifs via machine learning. Nucleic Acids Res 2024; 52:2188-2197. [PMID: 38364855 PMCID: PMC10954440 DOI: 10.1093/nar/gkae092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 01/24/2024] [Accepted: 01/29/2024] [Indexed: 02/18/2024] Open
Abstract
i-Motifs (iMs), are secondary structures formed in cytosine-rich DNA sequences and are involved in multiple functions in the genome. Although putative iM forming sequences are widely distributed in the human genome, the folding status and strength of putative iMs vary dramatically. Much previous research on iM has focused on assessing the iM folding properties using biophysical experiments. However, there are no dedicated computational tools for predicting the folding status and strength of iM structures. Here, we introduce a machine learning pipeline, iM-Seeker, to predict both folding status and structural stability of DNA iMs. The programme iM-Seeker incorporates a Balanced Random Forest classifier trained on genome-wide iMab antibody-based CUT&Tag sequencing data to predict the folding status and an Extreme Gradient Boosting regressor to estimate the folding strength according to both literature biophysical data and our in-house biophysical experiments. iM-Seeker predicts DNA iM folding status with a classification accuracy of 81% and estimates the folding strength with coefficient of determination (R2) of 0.642 on the test set. Model interpretation confirms that the nucleotide composition of the C-rich sequence significantly affects iM stability, with a positive correlation with sequences containing cytosine and thymine and a negative correlation with guanine and adenine.
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Affiliation(s)
- Bibo Yang
- Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Dilek Guneri
- School of Pharmacy, University College London, London WC1N 1AX, UK
| | - Haopeng Yu
- Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Elisé P Wright
- Molecular Physiology School of Medicine, and Molecular Medicine Research Group, University of Western Sydney, Campbelltown, NSW 1797, Australia
| | - Wenqian Chen
- School of Pharmacy, University College London, London WC1N 1AX, UK
| | - Zoë A E Waller
- School of Pharmacy, University College London, London WC1N 1AX, UK
| | - Yiliang Ding
- Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
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2
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Feng Y, Ma X, Yang Y, Tao S, Ahmed A, Gong Z, Cheng X, Zhang W. The roles of DNA methylation on pH dependent i-motif (iM) formation in rice. Nucleic Acids Res 2024; 52:1243-1257. [PMID: 38180820 PMCID: PMC10853798 DOI: 10.1093/nar/gkad1245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 12/14/2023] [Accepted: 12/19/2023] [Indexed: 01/07/2024] Open
Abstract
I-motifs (iMs) are four-stranded non-B DNA structures containing C-rich DNA sequences. The formation of iMs is sensitive to pH conditions and DNA methylation, although the extent of which is still unknown in both humans and plants. To investigate this, we here conducted iMab antibody-based immunoprecipitation and sequencing (iM-IP-seq) along with bisulfite sequencing using CK (original genomic DNA without methylation-related treatments) and hypermethylated or demethylated DNA at both pH 5.5 and 7.0 in rice, establishing a link between pH, DNA methylation and iM formation on a genome-wide scale. We found that iMs folded at pH 7.0 displayed higher methylation levels than those formed at pH 5.5. DNA demethylation and hypermethylation differently influenced iM formation at pH 7.0 and 5.5. Importantly, CG hypo-DMRs (differentially methylated regions) and CHH (H = A, C and T) hyper-DMRs alone or coordinated with CG/CHG hyper-DMRs may play determinant roles in the regulation of pH dependent iM formation. Thus, our study shows that the nature of DNA sequences alone or combined with their methylation status plays critical roles in determining pH-dependent formation of iMs. It therefore deepens the understanding of the pH and methylation dependent modulation of iM formation, which has important biological implications and practical applications.
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Affiliation(s)
- Yilong Feng
- State Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, CIC-MCP, Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, China
| | - Xing Ma
- State Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, CIC-MCP, Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, China
| | - Ying Yang
- State Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, CIC-MCP, Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, China
| | - Shentong Tao
- State Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, CIC-MCP, Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, China
| | - Asgar Ahmed
- State Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, CIC-MCP, Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, China
- Bangladesh Wheat and Maize Research Institute (BWMRI), Nashipur, Dinajpur 5200, Bangladesh
| | - Zhiyun Gong
- Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding, Agricultural College of Yangzhou University, Yangzhou 225009, China
| | - Xuejiao Cheng
- State Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, CIC-MCP, Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, China
| | - Wenli Zhang
- State Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, CIC-MCP, Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, China
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3
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Li KS, Jordan D, Lin LY, McCarthy SE, Schneekloth JS, Yatsunyk LA. Crystal Structure of an i-Motif from the HRAS Oncogene Promoter. Angew Chem Int Ed Engl 2023; 62:e202301666. [PMID: 36995904 PMCID: PMC10330059 DOI: 10.1002/anie.202301666] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 03/22/2023] [Accepted: 03/28/2023] [Indexed: 03/31/2023]
Abstract
An i-motif is a non-canonical DNA structure implicated in gene regulation and linked to cancers. The C-rich strand of the HRAS oncogene, 5'-CGCCCGTGCCCTGCGCCCGCAACCCGA-3' (herein referred to as iHRAS), forms an i-motif in vitro but its exact structure was unknown. HRAS is a member of the RAS proto-oncogene family. About 19 % of US cancer patients carry mutations in RAS genes. We solved the structure of iHRAS at 1.77 Å resolution. The structure reveals that iHRAS folds into a double hairpin. The two double hairpins associate in an antiparallel fashion, forming an i-motif dimer capped by two loops on each end and linked by a connecting region. Six C-C+ base pairs form each i-motif core, and the core regions are extended by a G-G base pair and a cytosine stacking. Extensive canonical and non-canonical base pairing and stacking stabilizes the connecting region and loops. The iHRAS structure is the first atomic resolution structure of an i-motif from a human oncogene. This structure sheds light on i-motifs folding and function in the cell.
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Affiliation(s)
- Kevin S Li
- Department Chemistry and Biochemistry, Swarthmore College, 500 College Ave, Swarthmore, PA 19081, USA
| | - Deondre Jordan
- Department Chemistry and Biochemistry, Swarthmore College, 500 College Ave, Swarthmore, PA 19081, USA
| | - Linda Y Lin
- Department Chemistry and Biochemistry, Swarthmore College, 500 College Ave, Swarthmore, PA 19081, USA
| | - Sawyer E McCarthy
- Department Chemistry and Biochemistry, Swarthmore College, 500 College Ave, Swarthmore, PA 19081, USA
| | - John S Schneekloth
- Chemical Biology Laboratory, National Cancer Institute, National Institute of Health, Frederick, MD 21702, USA
| | - Liliya A Yatsunyk
- Department Chemistry and Biochemistry, Swarthmore College, 500 College Ave, Swarthmore, PA 19081, USA
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4
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Li Z, Song W, Zhu Y, Yan L, Zhong X, Zhang M, Li H. The Full Cytosine-Cytosine Base Paring: Self-Assembly and Crystal Structure. Chemistry 2023; 29:e202203979. [PMID: 36757279 DOI: 10.1002/chem.202203979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 02/06/2023] [Accepted: 02/07/2023] [Indexed: 02/10/2023]
Abstract
The synthesis of self-assembly systems that can mimic partial biological behaviours require ingenious and delicate design. For decades, scientists are committed to exploring new base pairing patterns using hydrogen bonds directed self-assembly of nucleotides. A fundamental question is the adaptive circumstance of the recognition between base pairs, namely, how solvent conditions affect the domain of base pairs. Towards this question, three nucleotide complexes based on 2'-deoxycytidine-5'-monophosphate (dCMP) and cytidine-5'-monophosphate (CMP) were synthesized in different solvents and pH values, and an unusual cytosine-cytosine base paring pattern (named full C : C base pairing) has been successfully obtained. Systematic single crystal analysis and 1 H NMR titration spectra have been performed to explore factors influencing the formation of base paring patterns. Moreover, supramolecular chirality of three complexes were studied using circular dichroism (CD) spectroscopy in solution and solid-state combined with crystal structure analysis.
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Affiliation(s)
- Zhongkui Li
- Key Laboratory of Medicinal Molecule Science and Pharmaceutical Engineering, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, P. R. China
| | - Wenjing Song
- Key Laboratory of Medicinal Molecule Science and Pharmaceutical Engineering, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, P. R. China
| | - Yanhong Zhu
- Key Laboratory of Medicinal Molecule Science and Pharmaceutical Engineering, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, P. R. China
| | - Li Yan
- Key Laboratory of Medicinal Molecule Science and Pharmaceutical Engineering, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, P. R. China
| | - Xue Zhong
- Key Laboratory of Medicinal Molecule Science and Pharmaceutical Engineering, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, P. R. China
| | - Menglei Zhang
- Key Laboratory of Medicinal Molecule Science and Pharmaceutical Engineering, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, P. R. China
| | - Hui Li
- Key Laboratory of Medicinal Molecule Science and Pharmaceutical Engineering, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, P. R. China
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Sarkar S, Colón-Roura G, Pearse A, Armitage BA. Targeting a KRAS i-motif forming sequence by unmodified and gamma-modified peptide nucleic acid oligomers. Biopolymers 2023; 114:e23529. [PMID: 36573547 PMCID: PMC10078108 DOI: 10.1002/bip.23529] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 12/04/2022] [Accepted: 12/07/2022] [Indexed: 12/28/2022]
Abstract
Growing interest in i-motif DNA as a transcriptional regulatory element motivates development of synthetic molecules capable of targeting these structures. In this study, we designed unmodified peptide nucleic acid (PNA) and gamma-modified PNA (γPNA) oligomers complementary to an i-motif forming sequence derived from the promoter of the KRAS oncogene. Biophysical techniques such as circular dichroism (CD) spectroscopy, CD melting, and fluorescence spectroscopy demonstrated the successful invasion of the i-motif by PNA and γPNA. Both PNA and γPNA showed very strong binding to the target sequence with high thermal stability of the resulting heteroduplexes. Interestingly fluorescence and CD experiments indicated formation of an intermolecular i-motif structure via the overhangs of target-probe heteroduplexes formed by PNA/γPNA invasion of the intramolecular i-motif. Targeting promoter i-motif forming sequences with high-affinity oligonucleotide mimics like γPNAs may represent a new approach for inhibiting KRAS transcription, thereby representing a potentially useful anti-cancer strategy.
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Affiliation(s)
- Srijani Sarkar
- Department of Chemistry and Center for Nucleic Acids Science and Technology, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
| | - Gabriela Colón-Roura
- Department of Chemistry and Center for Nucleic Acids Science and Technology, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
| | - Alexander Pearse
- Department of Chemistry and Center for Nucleic Acids Science and Technology, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
| | - Bruce A Armitage
- Department of Chemistry and Center for Nucleic Acids Science and Technology, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
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6
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Yang T, Xu Q, Chen J, Jia PK, Xie BB, Wang D, Zhou X, Shao Y. Selectively Identifying Exposed-over-Unexposed C-C + Pairs in Human Telomeric i-Motif Structures with Length-Dependent Polymorphism. Anal Chem 2022; 94:14994-15001. [PMID: 36263663 DOI: 10.1021/acs.analchem.2c02875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The i-motif structure (iM) has attracted much attention, because of its in vivo bioactivity and wide in vitro applications such as DNA-based switches. Herein, the length-dependent folding of cytosine-rich repeats of the human telomeric 5'-(CCCTAA)n-1CCC-3' (iM-n, where n = 2-8) was fully explored. We found that iM-4, iM-5, and iM-8 mainly form the intramolecular monomer iM structures, while a tetramolecular structure populates only for iM-3. However, iM-6 and iM-7 have the potential to fold as well into the dimeric iM structures besides the monomer ones. The natural hypericin (Hyp) was used as the polymorphism-selective probe to recognize the iM structures. Interestingly, only iM-3, iM-6, and iM-7 can efficiently switch on the Hyp fluorescence by specifically binding with the outmost C-C+ base pairs that are exposed directly to solution. However, other iM structures that fold in a way with a coverage of the outmost C-C+ pairs by loop sequences are totally unavailable for the Hyp binding. Theoretical modeling indicates that adaptive π-π and cation-π interactions contribute to the Hyp recognition toward the exposed C-C+ pairs. This specific iM recognition can be boosted by a photocatalytic DNAzyme construct. Our work provides a reliable fluorescence method to selectively explore the polymorphism of iM structures.
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Affiliation(s)
- Tong Yang
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, People's Republic of China
| | - Qiuda Xu
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, People's Republic of China
| | - Jiahui Chen
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, People's Republic of China
| | - Pei-Ke Jia
- Hangzhou Institute of Advanced Studies, Zhejiang Normal University, 1108 Gengwen Road, Hangzhou 311231, Zhejiang, People's Republic of China
| | - Bin-Bin Xie
- Hangzhou Institute of Advanced Studies, Zhejiang Normal University, 1108 Gengwen Road, Hangzhou 311231, Zhejiang, People's Republic of China
| | - Dandan Wang
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, People's Republic of China
| | - Xiaoshun Zhou
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, People's Republic of China
| | - Yong Shao
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, People's Republic of China
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7
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Panczyk T, Nieszporek J, Nieszporek K. Molecular Dynamics Simulations of Interactions between Human Telomeric i-Motif Deoxyribonucleic Acid and Functionalized Graphene. J Phys Chem B 2022; 126:6671-6681. [PMID: 36036695 PMCID: PMC9465685 DOI: 10.1021/acs.jpcb.2c04327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 08/08/2022] [Indexed: 11/30/2022]
Abstract
The work deals with molecular dynamics (MD) simulations of protonated, human telomeric i-motif deoxyribonucleic acid (DNA) with functionalized graphene. We studied three different graphene sheets: unmodified graphene with hydrogen atoms attached to their edges and two functionalized ones. The functionalization of graphene edge consists in attaching partially protonated or dissociated amine and carboxyl groups. We found that in all cases the protonated i-motif adsorbs strongly on the graphene surface. The biased MD simulations showed that the work necessary to drag the i-motif out from amine-doped graphene is about twice larger than that in other cases. In general, the system i-motif/amine-doped graphene stands out from the rest, e.g., in this case, the i-motif adsorbs its side with 3' and 5' ends oriented in the opposite to surface direction. In other cases, the DNA fragment is adsorbed to graphene by 3' and 5' ends. In all cases, the adsorption on graphene influences the i-motif internal structure by changing the distances between i-motif strands as well as stretching or shortening the DNA chain, but only in the case of amine-doped graphene the adsorption affects internal H-bonds formed between nucleotides inside the i-motif structure.
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Affiliation(s)
- Tomasz Panczyk
- Institute
of Catalysis and Surface Chemistry, Polish Academy of Sciences, ul. Niezapominajek 8, Cracow 30239, Poland
| | - Jolanta Nieszporek
- Department
of Analytical Chemistry, Institute of Chemical
Sciences, Faculty of Chemistry, Maria Curie-Sklodowska University, pl. Maria Curie-Sklodowska 3, Lublin 20031, Poland
| | - Krzysztof Nieszporek
- Department
of Theoretical Chemistry, Institute of Chemical
Sciences, Faculty of Chemistry, Maria Curie-Sklodowska University, pl. Maria Curie-Sklodowska 3, Lublin 20031, Poland
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8
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Ma X, Feng Y, Yang Y, Li X, Shi Y, Tao S, Cheng X, Huang J, Wang XE, Chen C, Monchaud D, Zhang W. Genome-wide characterization of i-motifs and their potential roles in the stability and evolution of transposable elements in rice. Nucleic Acids Res 2022; 50:3226-3238. [PMID: 35188565 PMCID: PMC8989525 DOI: 10.1093/nar/gkac121] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 01/13/2022] [Accepted: 02/07/2022] [Indexed: 12/15/2022] Open
Abstract
I-motifs (iMs) are non-canonical DNA secondary structures that fold from cytosine (C)-rich genomic DNA regions termed putative i-motif forming sequences (PiMFSs). The structure of iMs is stabilized by hemiprotonated C-C base pairs, and their functions are now suspected in key cellular processes in human cells such as genome stability and regulation of gene transcription. In plants, their biological relevance is still largely unknown. Here, we characterized PiMFSs with high potential for i-motif formation in the rice genome by developing and applying a protocol hinging on an iMab antibody-based immunoprecipitation (IP) coupled with high-throughput sequencing (seq), consequently termed iM-IP-seq. We found that PiMFSs had intrinsic subgenomic distributions, cis-regulatory functions and an intricate relationship with DNA methylation. We indeed found that the coordination of PiMFSs with DNA methylation may affect dynamics of transposable elements (TEs) among different cultivated Oryza subpopulations or during evolution of wild rice species. Collectively, our study provides first and unique insights into the biology of iMs in plants, with potential applications in plant biotechnology for improving important agronomic rice traits.
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Affiliation(s)
- Xing Ma
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Collaborative Innovation Center for Modern Crop Production co-sponsored by Province and Ministry (CIC-MCP), Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, P.R. China
| | - Yilong Feng
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Collaborative Innovation Center for Modern Crop Production co-sponsored by Province and Ministry (CIC-MCP), Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, P.R. China
| | - Ying Yang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Collaborative Innovation Center for Modern Crop Production co-sponsored by Province and Ministry (CIC-MCP), Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, P.R. China
| | - Xin Li
- Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan410125, P.R. China
| | - Yining Shi
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Collaborative Innovation Center for Modern Crop Production co-sponsored by Province and Ministry (CIC-MCP), Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, P.R. China
| | - Shentong Tao
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Collaborative Innovation Center for Modern Crop Production co-sponsored by Province and Ministry (CIC-MCP), Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, P.R. China
| | - Xuejiao Cheng
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Collaborative Innovation Center for Modern Crop Production co-sponsored by Province and Ministry (CIC-MCP), Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, P.R. China
| | - Jian Huang
- School of Biology & Basic Medical Science, Soochow University, Suzhou, Jiangsu 215123, P.R. China
| | - Xiu-e Wang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Collaborative Innovation Center for Modern Crop Production co-sponsored by Province and Ministry (CIC-MCP), Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, P.R. China
| | - Caiyan Chen
- Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan410125, P.R. China
| | - David Monchaud
- Institut de Chimie Moleculaire, ICMUB CNRS UMR 6302, UBFC Dijon, France
| | - Wenli Zhang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Collaborative Innovation Center for Modern Crop Production co-sponsored by Province and Ministry (CIC-MCP), Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, P.R. China
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Marini M, Legittimo F, Torre B, Allione M, Limongi T, Scaltrito L, Pirri CF, di Fabrizio E. DNA Studies: Latest Spectroscopic and Structural Approaches. MICROMACHINES 2021; 12:mi12091094. [PMID: 34577737 PMCID: PMC8465297 DOI: 10.3390/mi12091094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 08/28/2021] [Accepted: 09/04/2021] [Indexed: 11/16/2022]
Abstract
This review looks at the different approaches, techniques, and materials devoted to DNA studies. In the past few decades, DNA nanotechnology, micro-fabrication, imaging, and spectroscopies have been tailored and combined for a broad range of medical-oriented applications. The continuous advancements in miniaturization of the devices, as well as the continuous need to study biological material structures and interactions, down to single molecules, have increase the interdisciplinarity of emerging technologies. In the following paragraphs, we will focus on recent sensing approaches, with a particular effort attributed to cutting-edge techniques for structural and mechanical studies of nucleic acids.
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Affiliation(s)
- Monica Marini
- Dipartimento di Scienza Applicata e Tecnologia (DISAT), Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy; (F.L.); (B.T.); (T.L.); (L.S.); (C.F.P.); (E.d.F.)
- Correspondence: ; Tel.: +39-011-090-43-22
| | - Francesca Legittimo
- Dipartimento di Scienza Applicata e Tecnologia (DISAT), Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy; (F.L.); (B.T.); (T.L.); (L.S.); (C.F.P.); (E.d.F.)
| | - Bruno Torre
- Dipartimento di Scienza Applicata e Tecnologia (DISAT), Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy; (F.L.); (B.T.); (T.L.); (L.S.); (C.F.P.); (E.d.F.)
| | - Marco Allione
- Istituto Italiano di Tecnologia (IIT), Via Livorno 60, 10144 Torino, Italy;
| | - Tania Limongi
- Dipartimento di Scienza Applicata e Tecnologia (DISAT), Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy; (F.L.); (B.T.); (T.L.); (L.S.); (C.F.P.); (E.d.F.)
| | - Luciano Scaltrito
- Dipartimento di Scienza Applicata e Tecnologia (DISAT), Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy; (F.L.); (B.T.); (T.L.); (L.S.); (C.F.P.); (E.d.F.)
| | - Candido Fabrizio Pirri
- Dipartimento di Scienza Applicata e Tecnologia (DISAT), Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy; (F.L.); (B.T.); (T.L.); (L.S.); (C.F.P.); (E.d.F.)
- Istituto Italiano di Tecnologia (IIT), Via Livorno 60, 10144 Torino, Italy;
| | - Enzo di Fabrizio
- Dipartimento di Scienza Applicata e Tecnologia (DISAT), Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy; (F.L.); (B.T.); (T.L.); (L.S.); (C.F.P.); (E.d.F.)
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10
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Lu S, Shen J, Fan C, Li Q, Yang X. DNA Assembly-Based Stimuli-Responsive Systems. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:2100328. [PMID: 34258165 PMCID: PMC8261508 DOI: 10.1002/advs.202100328] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 03/05/2021] [Indexed: 05/06/2023]
Abstract
Stimuli-responsive designs with exogenous stimuli enable remote and reversible control of DNA nanostructures, which break many limitations of static nanostructures and inspired development of dynamic DNA nanotechnology. Moreover, the introduction of various types of organic molecules, polymers, chemical bonds, and chemical reactions with stimuli-responsive properties development has greatly expand the application scope of dynamic DNA nanotechnology. Here, DNA assembly-based stimuli-responsive systems are reviewed, with the focus on response units and mechanisms that depend on different exogenous stimuli (DNA strand, pH, light, temperature, electricity, metal ions, etc.), and their applications in fields of nanofabrication (DNA architectures, hybrid architectures, nanomachines, and constitutional dynamic networks) and biomedical research (biosensing, bioimaging, therapeutics, and theranostics) are discussed. Finally, the opportunities and challenges for DNA assembly-based stimuli-responsive systems are overviewed and discussed.
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Affiliation(s)
- Shasha Lu
- School of Chemistry and Chemical EngineeringFrontiers Science Center for Transformative MoleculesInstitute of Translational MedicineShanghai Jiao Tong UniversityShanghai200240China
| | - Jianlei Shen
- School of Chemistry and Chemical EngineeringFrontiers Science Center for Transformative MoleculesInstitute of Translational MedicineShanghai Jiao Tong UniversityShanghai200240China
| | - Chunhai Fan
- School of Chemistry and Chemical EngineeringFrontiers Science Center for Transformative MoleculesInstitute of Translational MedicineShanghai Jiao Tong UniversityShanghai200240China
- Institute of Molecular MedicineShanghai Key Laboratory for Nucleic Acid Chemistry and NanomedicineDepartment of UrologyRenji HospitalSchool of MedicineShanghai Jiao Tong UniversityShanghai200127China
| | - Qian Li
- School of Chemistry and Chemical EngineeringFrontiers Science Center for Transformative MoleculesInstitute of Translational MedicineShanghai Jiao Tong UniversityShanghai200240China
| | - Xiurong Yang
- School of Chemistry and Chemical EngineeringFrontiers Science Center for Transformative MoleculesInstitute of Translational MedicineShanghai Jiao Tong UniversityShanghai200240China
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11
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Chaudhuri R, Fatma K, Dash J. Regulation of gene expression by targeting DNA secondary structures. J CHEM SCI 2021. [DOI: 10.1007/s12039-021-01898-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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12
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Cheng M, Chen J, Ju H, Zhou J, Mergny JL. Drivers of i-DNA Formation in a Variety of Environments Revealed by Four-Dimensional UV Melting and Annealing. J Am Chem Soc 2021; 143:7792-7807. [PMID: 33988990 DOI: 10.1021/jacs.1c02209] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
i-DNA is a four-stranded, pH-sensitive structure formed by cytosine-rich DNA sequences. Previous reports have addressed the conditions for formation of this motif in DNA in vitro and validated its existence in human cells. Unfortunately, these in vitro studies have often been performed under different experimental conditions, making comparisons difficult. To overcome this, we developed a four-dimensional UV melting and annealing (4DUVMA) approach to analyze i-DNA formation under a variety of conditions (e.g., pH, temperature, salt, crowding). Analysis of 25 sequences provided a global understanding of i-DNA formation under disparate conditions, which should ultimately allow the design of accurate prediction tools. For example, we found reliable linear correlations between the midpoint of pH transition and temperature (-0.04 ± 0.003 pH unit per 1.0 °C temperature increment) and between the melting temperature and pH (-23.8 ± 1.1 °C per pH unit increment). In addition, by analyzing the hysteresis between denaturing and renaturing profiles in both pH and thermal transitions, we found that loop length, nature of the C-tracts, pH, temperature, and crowding agents all play roles in i-DNA folding kinetics. Interestingly, our data indicate which conformer is more favorable for the sequences with an odd number of cytosine base pairs. Then the thermal and pH stabilities of "native" i-DNAs from human promoter genes were measured under near physiological conditions (pH 7.0, 37 °C). The 4DUVMA method can become a universal resource to analyze the properties of any i-DNA-prone sequence.
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Affiliation(s)
- Mingpan Cheng
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210023, China.,ARNA Laboratory, Université de Bordeaux, INSERM U1212, CNRS UMR5320, IECB, Pessac 33607, France
| | - Jielin Chen
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Huangxian Ju
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Jun Zhou
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Jean-Louis Mergny
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210023, China.,ARNA Laboratory, Université de Bordeaux, INSERM U1212, CNRS UMR5320, IECB, Pessac 33607, France.,Laboratoire d'Optique et Biosciences, Ecole Polytechnique, CNRS, INSERM, Institut Polytechnique de Paris, Palaiseau Cedex 91128, France
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13
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Crucial Role of the C-Terminal Domain of Hfq Protein in Genomic Instability. Microorganisms 2020; 8:microorganisms8101598. [PMID: 33080799 PMCID: PMC7603069 DOI: 10.3390/microorganisms8101598] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 10/10/2020] [Accepted: 10/13/2020] [Indexed: 01/25/2023] Open
Abstract
G-rich DNA repeats that can form G-quadruplex structures are prevalent in bacterial genomes and are frequently associated with regulatory regions of genes involved in virulence, antigenic variation, and antibiotic resistance. These sequences are also inherently mutagenic and can lead to changes affecting cell survival and adaptation. Transcription of the G-quadruplex-forming repeat (G3T)n in E. coli, when mRNA comprised the G-rich strand, promotes G-quadruplex formation in DNA and increases rates of deletion of G-quadruplex-forming sequences. The genomic instability of G-quadruplex repeats may be a source of genetic variability that can influence alterations and evolution of bacteria. The DNA chaperone Hfq is involved in the genetic instability of these G-quadruplex sequences. Inactivation of the hfq gene decreases the genetic instability of G-quadruplex, demonstrating that the genomic instability of this regulatory element can be influenced by the E. coli highly pleiotropic Hfq protein, which is involved in small noncoding RNA regulation pathways, and DNA organization and packaging. We have shown previously that the protein binds to and stabilizes these sequences, increasing rates of their genomic instability. Here, we extend this analysis to characterize the role of the C-terminal domain of Hfq protein in interaction with G-quadruplex structures. This allows to better understand the function of this specific region of the Hfq protein in genomic instability.
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14
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Chatterjee K, Dopfer O. Microhydration of protonated biomolecular building blocks: protonated pyrimidine. Phys Chem Chem Phys 2020; 22:13092-13107. [PMID: 32490447 DOI: 10.1039/d0cp02110e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Protonation and hydration of biomolecules govern their structure, conformation, and function. Herein, we explore the microhydration structure in mass-selected protonated pyrimidine-water clusters (H+Pym-Wn, n = 1-4) by a combination of infrared photodissociation spectroscopy (IRPD) between 2450 and 3900 cm-1 and density functional theory (DFT) calculations at the dispersion-corrected B3LYP-D3/aug-cc-pVTZ level. We further present the IR spectrum of H+Pym-N2 to evaluate the effect of solvent polarity on the intrinsic molecular parameters of H+Pym. Our combined spectroscopic and computational approach unequivocally shows that protonation of Pym occurs at one of the two equivalent basic ring N atoms and that the ligands in H+Pym-L (L = N2 or W) preferentially form linear H-bonds to the resulting acidic NH group. Successive addition of water ligands results in the formation of a H-bonded solvent network which increasingly weakens the NH group. Despite substantial activation of the N-H bond upon microhydration, no intracluster proton transfer occurs up to n = 4 because of the balance of relative proton affinities of Pym and Wn and the involved solvation energies. Comparison to neutral Pym-Wn clusters reveals the drastic effects of protonation on microhydration with respect to both structure and interaction strength.
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Affiliation(s)
- Kuntal Chatterjee
- Institut für Optik und Atomare Physik, TU Berlin, Hardenbergstr. 36, 10623 Berlin, Germany.
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15
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Paul S, Hossain SS, Samanta A. Insights into the Folding Pathway of a c-MYC-Promoter-Based i-Motif DNA in Crowded Environments at the Single-Molecule Level. J Phys Chem B 2020; 124:763-770. [DOI: 10.1021/acs.jpcb.9b10633] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Sneha Paul
- School of Chemistry, University of Hyderabad, Hyderabad 500046, India
| | - Sk Saddam Hossain
- School of Chemistry, University of Hyderabad, Hyderabad 500046, India
| | - Anunay Samanta
- School of Chemistry, University of Hyderabad, Hyderabad 500046, India
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16
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Parekh VJ, Niccum BA, Shah R, Rivera MA, Novak MJ, Geinguenaud F, Wien F, Arluison V, Sinden RR. Role of Hfq in Genome Evolution: Instability of G-Quadruplex Sequences in E. coli. Microorganisms 2019; 8:microorganisms8010028. [PMID: 31877879 PMCID: PMC7023247 DOI: 10.3390/microorganisms8010028] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 12/16/2019] [Accepted: 12/17/2019] [Indexed: 11/16/2022] Open
Abstract
Certain G-rich DNA repeats can form quadruplex in bacterial chromatin that can present blocks to DNA replication and, if not properly resolved, may lead to mutations. To understand the participation of quadruplex DNA in genomic instability in Escherichia coli (E. coli), mutation rates were measured for quadruplex-forming DNA repeats, including (G3T)4, (G3T)8, and a RET oncogene sequence, cloned as the template or nontemplate strand. We evidence that these alternative structures strongly influence mutagenesis rates. Precisely, our results suggest that G-quadruplexes form in E. coli cells, especially during transcription when the G-rich strand can be displaced by R-loop formation. Structure formation may then facilitate replication misalignment, presumably associated with replication fork blockage, promoting genomic instability. Furthermore, our results also evidence that the nucleoid-associated protein Hfq is involved in the genetic instability associated with these sequences. Hfq binds and stabilizes G-quadruplex structure in vitro and likely in cells. Collectively, our results thus implicate quadruplexes structures and Hfq nucleoid protein in the potential for genetic change that may drive evolution or alterations of bacterial gene expression.
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Affiliation(s)
- Virali J. Parekh
- Laboratory of DNA Structure and Mutagenesis, Department of Chemistry and Applied Biological Sciences, South Dakota School of Mines and Technology, Rapid City, SD 57701, USA;
| | - Brittany A. Niccum
- Department of Mathematics, Florida Institute of Technology, Melbourne, FL 32901, USA;
| | - Rachna Shah
- Department of Biological Sciences, Florida Institute of Technology, Melbourne, FL 32901, USA; (R.S.); (M.A.R.)
| | - Marisa A. Rivera
- Department of Biological Sciences, Florida Institute of Technology, Melbourne, FL 32901, USA; (R.S.); (M.A.R.)
| | - Mark J. Novak
- Department of Chemistry and Applied Biological Sciences, South Dakota School of Mines and Technology; Rapid City, SD 57701, USA;
| | - Frederic Geinguenaud
- Plateforme CNanoMat & Inserm U1148, Laboratory for Vascular Translational Science, UFR SMBH, Université Paris 13, Sorbonne Paris Cité, F-93017 Bobigny, France;
| | - Frank Wien
- Synchrotron SOLEIL, 91192 Gif-sur-Yvette, France;
| | - Véronique Arluison
- Laboratoire Léon Brillouin LLB, CEA, CNRS UMR12, Université Paris Saclay, CEA Saclay, 91191 Gif-sur-Yvette, France
- Université de Paris, UFR Sciences du vivant, 35 rue Hélène Brion, 75205 Paris cedex, France
- Correspondence: (V.A.); (R.R.S.); Tel.: +1-605-394-1678 (R.R.S.)
| | - Richard R. Sinden
- Laboratory of DNA Structure and Mutagenesis, Department of Chemistry and Applied Biological Sciences, South Dakota School of Mines and Technology, Rapid City, SD 57701, USA;
- Correspondence: (V.A.); (R.R.S.); Tel.: +1-605-394-1678 (R.R.S.)
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17
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Conlon PF, Eguaogie O, Wilson JJ, Sweet JST, Steinhoegl J, Englert K, Hancox OGA, Law CJ, Allman SA, Tucker JHR, Hall JP, Vyle JS. Solid-phase synthesis and structural characterisation of phosphoroselenolate-modified DNA: a backbone analogue which does not impose conformational bias and facilitates SAD X-ray crystallography. Chem Sci 2019; 10:10948-10957. [PMID: 32190252 PMCID: PMC7066676 DOI: 10.1039/c9sc04098f] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 10/11/2019] [Indexed: 01/20/2023] Open
Abstract
Oligodeoxynucleotides incorporating internucleotide phosphoroselenolate linkages have been prepared under solid-phase synthesis conditions using dimer phosphoramidites. These dimers were constructed following the high yielding Michaelis-Arbuzov (M-A) reaction of nucleoside H-phosphonate derivatives with 5'-deoxythymidine-5'-selenocyanate and subsequent phosphitylation. Efficient coupling of the dimer phosphoramidites to solid-supported substrates was observed under both manual and automated conditions and required only minor modifications to the standard DNA synthesis cycle. In a further demonstration of the utility of M-A chemistry, the support-bound selenonucleoside was reacted with an H-phosphonate and then chain extended using phosphoramidite chemistry. Following initial unmasking of methyl-protected phosphoroselenolate diesters, pure oligodeoxynucleotides were isolated using standard deprotection and purification procedures and subsequently characterised by mass spectrometry and circular dichroism. The CD spectra of both modified and native duplexes derived from self-complementary sequences with A-form, B-form or mixed conformational preferences were essentially superimposable. These sequences were also used to study the effect of the modification upon duplex stability which showed context-dependent destabilisation (-0.4 to -3.1 °C per phosphoroselenolate) when introduced at the 5'-termini of A-form or mixed duplexes or at juxtaposed central loci within a B-form duplex (-1.0 °C per modification). As found with other nucleic acids incorporating selenium, expeditious crystallisation of a modified decanucleotide A-form duplex was observed and the structure solved to a resolution of 1.45 Å. The DNA structure adjacent to the modification was not significantly perturbed. The phosphoroselenolate linkage was found to impart resistance to nuclease activity.
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Affiliation(s)
- Patrick F Conlon
- School of Chemistry and Chemical Engineering , Queen's University Belfast , David Keir Building, Stranmillis Road , Belfast , BT9 5AG , UK .
| | - Olga Eguaogie
- School of Chemistry and Chemical Engineering , Queen's University Belfast , David Keir Building, Stranmillis Road , Belfast , BT9 5AG , UK .
| | - Jordan J Wilson
- School of Chemistry and Chemical Engineering , Queen's University Belfast , David Keir Building, Stranmillis Road , Belfast , BT9 5AG , UK .
| | - Jamie S T Sweet
- School of Chemistry and Chemical Engineering , Queen's University Belfast , David Keir Building, Stranmillis Road , Belfast , BT9 5AG , UK .
| | - Julian Steinhoegl
- Reading School of Pharmacy , University of Reading , Whiteknights , Reading RG6 6AP , UK .
| | - Klaudia Englert
- School of Chemistry , University of Birmingham , Edgbaston , Birmingham B15 2TT , UK
| | - Oliver G A Hancox
- Reading School of Pharmacy , University of Reading , Whiteknights , Reading RG6 6AP , UK .
| | - Christopher J Law
- School of Biological Sciences , Queen's University Belfast , 15 Chlorine Gardens , Belfast BT9 5AH , UK
| | - Sarah A Allman
- Reading School of Pharmacy , University of Reading , Whiteknights , Reading RG6 6AP , UK .
| | - James H R Tucker
- School of Chemistry , University of Birmingham , Edgbaston , Birmingham B15 2TT , UK
| | - James P Hall
- Reading School of Pharmacy , University of Reading , Whiteknights , Reading RG6 6AP , UK .
- Diamond Light Source , Chilton , Didcot , Oxfordshire OX11 0DE , UK
| | - Joseph S Vyle
- School of Chemistry and Chemical Engineering , Queen's University Belfast , David Keir Building, Stranmillis Road , Belfast , BT9 5AG , UK .
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18
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Belmonte-Reche E, Morales JC. G4-iM Grinder: when size and frequency matter. G-Quadruplex, i-Motif and higher order structure search and analysis tool. NAR Genom Bioinform 2019; 2:lqz005. [PMID: 33575559 PMCID: PMC7671307 DOI: 10.1093/nargab/lqz005] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 08/08/2019] [Accepted: 09/10/2019] [Indexed: 11/15/2022] Open
Abstract
We present G4-iM Grinder, a system for the localization, characterization and selection of potential G4s, i-Motifs and higher order structures. A robust and highly adaptable search engine identifies all structures that fit the user’s quadruplex definitions. Their biological relevance, in vitro formation probability and presence of known-to-form structures are then used as filters. The outcome is an efficient methodology that helps select the best candidates for a subsequent in vitro analysis or a macroscopic genomic quadruplex assessment. As proof of the analytical capabilities of G4-iM Grinder, the human genome was analyzed for potential G4s and i-Motifs. Many known-to-form structures were identified. New candidates were selected considering their score and appearance frequency. We also focused on locating Potential Higher Order Quadruplex Sequences (PHOQS). We developed a new methodology to predict the most probable subunits of these assemblies and applied it to a PHOQS candidate. Taking the human average density as reference, we examined the genomes of several etiological causes of disease. This first of its class comparative study found many organisms to be very dense in these potential quadruplexes. Many presented already known-to-form-G4s and i-Motifs. These findings suggest the potential quadruplexes have as therapeutic targets for these diseases that currently kill millions worldwide.
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Affiliation(s)
- Efres Belmonte-Reche
- Department of Biochemistry and Molecular Pharmacology, Instituto de Parasitología y Biomedicina López Neyra, CSIC, PTS Granada, Avda. del Conocimiento, 17, 18016 Armilla, Granada, Spain.,Life Sciences Department, International Iberian Nanotechnology Laboratory, Av. Mestre José Veiga, 4715-330 Braga, Portugal
| | - Juan Carlos Morales
- Department of Biochemistry and Molecular Pharmacology, Instituto de Parasitología y Biomedicina López Neyra, CSIC, PTS Granada, Avda. del Conocimiento, 17, 18016 Armilla, Granada, Spain
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19
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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: 230] [Impact Index Per Article: 46.0] [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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20
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Cheng R, Loire E, Fridgen TD. Hydrogen bonding in alkali metal cation-bound i-motif-like dimers of 1-methyl cytosine: an IRMPD spectroscopic and computational study. Phys Chem Chem Phys 2019; 21:11103-11110. [PMID: 31094375 DOI: 10.1039/c9cp01223k] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The structures of alkali metal cation bound 1-methylcytosine (1-mCyt) dimers were explored using vibrational spectroscopy in the form of infrared multiple photon dissociation (IRMPD) spectroscopy and by computational methods. For the smaller alkali metal cations, Li+ and Na+, only non-hydrogen bonded symmetric anti-parallel structures were observed in agreement with the lowest energy computed structures. For K+, Rb+, and Cs+ the vibrational spectra in the N-H stretch region showed strong evidence for hydrogen bonding in agreement with the lowest energy structures which contained hydrogen bonding interactions between the amine group of one cytosine and the carbonyl oxygen of the other cytosine. The lowest energy structures for these complexes were compared to previously studied cytosine complexes [(Cyt)2M]+ where M = Li, Na, and K. The calculations are in agreement that only the non-hydrogen bonded structures would be observed for these cytosine complexes.
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Affiliation(s)
- Ruodi Cheng
- Department of Chemistry, Memorial University, St. John's, NL A1B 3 × 7, Canada.
| | - Estelle Loire
- Laboratoire Chimie Physique - CLIO, Batiment 201, Porte 2, Campus Universite d'Orsay, 91405, France
| | - Travis D Fridgen
- Department of Chemistry, Memorial University, St. John's, NL A1B 3 × 7, Canada.
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21
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Ma C, Chan RCT, Chan CTL, Wong AKW, Chung BPY, Kwok WM. Fluorescence and Ultrafast Fluorescence Unveil the Formation, Folding Molecularity, and Excitation Dynamics of Homo-Oligomeric and Human Telomeric i-Motifs at Acidic and Neutral pH. Chem Asian J 2018; 13:3706-3717. [PMID: 30230251 DOI: 10.1002/asia.201801117] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 08/28/2018] [Indexed: 01/07/2023]
Abstract
i-Motifs are tetraplex DNAs known to be stable at acidic pH. The structure of i-motifs is important in DNA nanotechnology; i-motif-forming sequences with consecutive cytosine (C) molecules are abundant throughout the human genome. There is, however, little information on the structure of C-rich DNAs under physiologically relevant neutral conditions. The electron dynamics of i-motifs, crucial to both biology and materials applications, also remains largely unexplored. In this work, we report a combined femtosecond and nanosecond broadband time-resolved fluorescence (TRF) and steady-state fluorescence investigation on homo-oligomer dC20 , a human telomeric sequence (HTS) 5'-dC3 (TA2 C3 )3 , and its analogue performed with different excitation at both acidic and neutral pH. Our study provides direct observation of intrinsic fluorescence and the first full probe of the real-time dynamics of the intrinsic fluorescence from i-motifs formed from varied sequences and pH conditions. The results obtained demonstrate concrete evidence for the existence at neutral pH of i-motifs from both dC20 and the HTS. It also identifies that, under neutral conditions, the i-motif from dC20 adopting the bimolecular folding structure is significantly more stable than the HTS i-motif featuring the unimolecular topology. Our femtosecond and nanosecond TRF study unveils excitation dynamics distinctive of the interdigitated architecture of i-motifs with the excited states involved exhibiting deactivation over a remarkably broad timescale through multiple channels involving proton-coupled electron transfer lasting tens of picoseconds, as signified by the solvent kinetic isotope effect, and structure-dependent charge recombination in the hundreds of picoseconds to tens of nanoseconds time regime.
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Affiliation(s)
- Chensheng Ma
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, Guangdong, P. R. China
| | - Ruth Chau-Ting Chan
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, P. R. China
| | - Chris Tsz-Leung Chan
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, Guangdong, P. R. China
| | - Allen Ka-Wa Wong
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, P. R. China
| | - Bowie Po-Yee Chung
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, P. R. China
| | - Wai-Ming Kwok
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, P. R. China
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22
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Ishida R, Iwahashi H. Detection of protonated non-Watson-Crick base pairs using electrospray ionization mass spectrometry. J Biochem 2018; 163:215-222. [PMID: 29087477 DOI: 10.1093/jb/mvx073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 09/11/2017] [Indexed: 11/13/2022] Open
Abstract
Many studies have shown that protonated nucleic acid base pairs are involved in a wide variety of nucleic acid structures. However, little information is available on relative stability of hemiprotonated self- and non-self-dimers at monomer level. We used electrospray ionization mass spectrometry (ESI-MS) to evaluate the relative stability under various concentrations of hydrogen ion. These enable conjecture of the formation of protonated non-Watson-Crick base pairs based on DNA and RNA base sequence. In the present study, we observed that ESI-MS peaks corresponded to respective self-dimers for all examined nucleosides except for adenosine. Peak heights depended on the concentration of hydrogen ion. The ESI-MS peak heights of the hemiprotonated cytidine dimers and the hemiprotonated thymidine dimer sharply increased with increased concentration of hydrogen ion, suggesting direct participation of hydrogen ion in dimer formations. In ESI-MS measurements of the solutions containing adenosine, cytidine, thymidine and guanosine, we observed protonated cytidine-guanosine dimer (CH+-G) and protonated cytidine-thymidine dimer (CH+-T) in addition to hemiprotonated cytidine-cytidine dimer (CH+-C) with following relative peak height, (CH+-C) > (CH+-G) ≈ (CH+-T) > (CH+-A). Additionally, in the ESI-MS measurements of solutions containing adenosine, thymidine and guanosine, we observed a considerable amount of protonated adenosine-guanosine (AH+-G) and protonated adenosine-thymidine (AH+-T).
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Affiliation(s)
- Riyoko Ishida
- Analytical Biochemistry, Wakayama Medical University, 580 Mikazura, Wakayama, Wakayama 641-0011, Japan
| | - Hideo Iwahashi
- Analytical Biochemistry, Wakayama Medical University, 580 Mikazura, Wakayama, Wakayama 641-0011, Japan
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23
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Hybrid DNA i-motif: Aminoethylprolyl-PNA (pC 5) enhance the stability of DNA (dC 5) i-motif structure. Bioorg Med Chem Lett 2017; 27:5424-5428. [PMID: 29138026 DOI: 10.1016/j.bmcl.2017.11.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 11/01/2017] [Accepted: 11/02/2017] [Indexed: 11/23/2022]
Abstract
This report describes the synthesis of C-rich sequence, cytosine pentamer, of aep-PNA and its biophysical studies for the formation of hybrid DNA:aep-PNAi-motif structure with DNA cytosine pentamer (dC5) under acidic pH conditions. Herein, the CD/UV/NMR/ESI-Mass studies strongly support the formation of stable hybrid DNA i-motif structure with aep-PNA even near acidic conditions. Hence aep-PNA C-rich sequence cytosine could be considered as potential DNA i-motif stabilizing agents in vivo conditions.
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24
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Assi HA, Harkness RW, Martin-Pintado N, Wilds CJ, Campos-Olivas R, Mittermaier AK, González C, Damha MJ. Stabilization of i-motif structures by 2'-β-fluorination of DNA. Nucleic Acids Res 2016; 44:4998-5009. [PMID: 27166371 PMCID: PMC4914123 DOI: 10.1093/nar/gkw402] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 05/02/2016] [Indexed: 01/12/2023] Open
Abstract
i-Motifs are four-stranded DNA structures consisting of two parallel DNA duplexes held together by hemi-protonated and intercalated cytosine base pairs (C:CH+). They have attracted considerable research interest for their potential role in gene regulation and their use as pH responsive switches and building blocks in macromolecular assemblies. At neutral and basic pH values, the cytosine bases deprotonate and the structure unfolds into single strands. To avoid this limitation and expand the range of environmental conditions supporting i-motif folding, we replaced the sugar in DNA by 2-deoxy-2-fluoroarabinose. We demonstrate that such a modification significantly stabilizes i-motif formation over a wide pH range, including pH 7. Nuclear magnetic resonance experiments reveal that 2-deoxy-2-fluoroarabinose adopts a C2′-endo conformation, instead of the C3′-endo conformation usually found in unmodified i-motifs. Nevertheless, this substitution does not alter the overall i-motif structure. This conformational change, together with the changes in charge distribution in the sugar caused by the electronegative fluorine atoms, leads to a number of favorable sequential and inter-strand electrostatic interactions. The availability of folded i-motifs at neutral pH will aid investigations into the biological function of i-motifs in vitro, and will expand i-motif applications in nanotechnology.
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Affiliation(s)
- Hala Abou Assi
- Department of Chemistry, McGill University, Montreal, QC H3A 0B8, Canada
| | - Robert W Harkness
- Department of Chemistry, McGill University, Montreal, QC H3A 0B8, Canada
| | | | - Christopher J Wilds
- Department of Chemistry, McGill University, Montreal, QC H3A 0B8, Canada Department of Chemistry and Biochemistry, Concordia University, Montreal, QC H4B 1R6, Canada
| | | | | | - Carlos González
- Instituto de Química Física 'Rocasolano', CSIC, 28006 Madrid, Spain
| | - Masad J Damha
- Department of Chemistry, McGill University, Montreal, QC H3A 0B8, Canada
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Nakano SI, Oka H, Fujii M, Sugimoto N. Use of a Ureido-Substituted Deoxycytidine Module for DNA Assemblies. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2016; 35:370-8. [PMID: 27152551 DOI: 10.1080/15257770.2016.1174262] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Ureido-substituted cytosine derivatives are promising for constructing self-assembly structures that can be applied to nanotechnology research. However, conventional cytosine modules achieve assembly in organic solvents. In this study, an N-phenylcarbamoyl deoxycytidine nucleoside was incorporated into a C-rich oligonucleotide to achieve self-assembly in aqueous solution. The results show that the capability of the module to form DNA assemblies varied depending on the number of modules incorporated. The deoxycytidine derivative has a potential application in the development of smart materials based on DNA assembly.
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Affiliation(s)
- Shu-Ichi Nakano
- a Department of Nanobiochemistry , Faculty of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University , Kobe , Japan
| | - Hirohito Oka
- b Department of Chemistry , Faculty of Science and Engineering, Konan University , Kobe , Japan
| | - Masayuki Fujii
- c Molecular Engineering Institute (MEI), Kinki University , Fukuoka , Japan.,d Department of Environmental and Biological Chemistry , Kinki University , Fukuoka , Japan
| | - Naoki Sugimoto
- a Department of Nanobiochemistry , Faculty of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University , Kobe , Japan.,e Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University , Kobe , Japan
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26
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Mitra SN, Biswas R, Shi K, Sundaralingam M. Crystal Structure of an RNA Duplex [r(gugcaca)dC](2) with 3'-Dinucleoside Overhangs Forming a Superhelix. J Biomol Struct Dyn 2016; 17 Suppl 1:189-94. [PMID: 22607423 DOI: 10.1080/07391102.2000.10506620] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Abstract Crystal structure of the RNA octamer duplex, [r(gugcaca)dC] (2), with space group I2(1)2(1)2(1) and the cell constants a=24.29, b=45.25 and c=73.68Å, has been determined and refined. The structural and packing architecture of the molecule consist of a highly bent six base paired duplex forming a right-handed superhelix stacked in tandem compared to an infinite pseudo- continuous column as is usually present in RNA crystal structures. The super helix could be formed by the head-to-head stacking (g1 over g1 and g9 over g9), the large bend and the twists at the junctions may also be responsible. The sugar-phosphate backbones of the 3'-end dinucleoside overhangs snuggly fit into the minor grooves of adjacent double helical stacks. The 3'-terminal deoxycytidines form antiparallel hemiprotonated trans (C·C)(+) pairs with symmetry related deoxycytidines, while the penultimate adenines form base triples (a*g·c) with the capping g·c base pairs of the hexamer duplex with the adenine (a7) at one end being syn and at the other anti. These triple interactions are the same as those found in the tetrahymena ribozyme and group I intron.
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Affiliation(s)
- S N Mitra
- a Biological Macromolecular Structure Center, Departments of Chemistry and Biochemistry , The Ohio State University , 012 Rightmire Hall, 1060 Carmack Road , Columbus , OH , 43210
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27
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Keane PM, Baptista FR, Gurung SP, Devereux SJ, Sazanovich IV, Towrie M, Brazier JA, Cardin CJ, Kelly JM, Quinn SJ. Long-Lived Excited-State Dynamics of i-Motif Structures Probed by Time-Resolved Infrared Spectroscopy. Chemphyschem 2016; 17:1281-7. [PMID: 26879336 DOI: 10.1002/cphc.201501183] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Indexed: 01/22/2023]
Abstract
UV-generated excited states of cytosine (C) nucleobases are precursors to mutagenic photoproduct formation. The i-motif formed from C-rich sequences is known to exhibit high yields of long-lived excited states following UV absorption. Here the excited states of several i-motif structures have been characterized following 267 nm laser excitation using time-resolved infrared spectroscopy (TRIR). All structures possess a long-lived excited state of ∼300 ps and notably in some cases decays greater than 1 ns are observed. These unusually long-lived lifetimes are attributed to the interdigitated DNA structure which prevents direct base stacking overlap.
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Affiliation(s)
- Páraic M Keane
- Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD, UK.
| | | | - Sarah P Gurung
- Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD, UK
- Diamond Light Source, Harwell Science and Innovation campus, Didcot, Oxfordshire, OX11 0QX, UK
| | - Stephen J Devereux
- School of Chemistry, University College Dublin, Belfield, Dublin 4, Ireland
| | - Igor V Sazanovich
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation campus, Didcot, Oxfordshire, OX11 0QX, UK
| | - Michael Towrie
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation campus, Didcot, Oxfordshire, OX11 0QX, UK
| | - John A Brazier
- Department of Pharmacy, University of Reading, Whiteknights, Reading, RG6 6AD, UK
| | - Christine J Cardin
- Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD, UK
| | - John M Kelly
- School of Chemistry, Trinity College Dublin, Dublin 2, Ireland
| | - Susan J Quinn
- School of Chemistry, University College Dublin, Belfield, Dublin 4, Ireland.
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28
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Huang J, Ying L, Yang X, Yang Y, Quan K, Wang H, Xie N, Ou M, Zhou Q, Wang K. Ratiometric Fluorescent Sensing of pH Values in Living Cells by Dual-Fluorophore-Labeled i-Motif Nanoprobes. Anal Chem 2015; 87:8724-31. [DOI: 10.1021/acs.analchem.5b01527] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Jin Huang
- State Key Laboratory of Chemo/Biosensing
and Chemometrics, College of Chemistry and Chemical Engineering, Key
Laboratory for Bio-Nanotechnology and Molecular Engineering of Hunan
Province, Hunan University, Changsha 410082, People’s Republic of China
| | - Le Ying
- State Key Laboratory of Chemo/Biosensing
and Chemometrics, College of Chemistry and Chemical Engineering, Key
Laboratory for Bio-Nanotechnology and Molecular Engineering of Hunan
Province, Hunan University, Changsha 410082, People’s Republic of China
| | - Xiaohai Yang
- State Key Laboratory of Chemo/Biosensing
and Chemometrics, College of Chemistry and Chemical Engineering, Key
Laboratory for Bio-Nanotechnology and Molecular Engineering of Hunan
Province, Hunan University, Changsha 410082, People’s Republic of China
| | - Yanjing Yang
- State Key Laboratory of Chemo/Biosensing
and Chemometrics, College of Chemistry and Chemical Engineering, Key
Laboratory for Bio-Nanotechnology and Molecular Engineering of Hunan
Province, Hunan University, Changsha 410082, People’s Republic of China
| | - Ke Quan
- State Key Laboratory of Chemo/Biosensing
and Chemometrics, College of Chemistry and Chemical Engineering, Key
Laboratory for Bio-Nanotechnology and Molecular Engineering of Hunan
Province, Hunan University, Changsha 410082, People’s Republic of China
| | - He Wang
- State Key Laboratory of Chemo/Biosensing
and Chemometrics, College of Chemistry and Chemical Engineering, Key
Laboratory for Bio-Nanotechnology and Molecular Engineering of Hunan
Province, Hunan University, Changsha 410082, People’s Republic of China
| | - Nuli Xie
- State Key Laboratory of Chemo/Biosensing
and Chemometrics, College of Chemistry and Chemical Engineering, Key
Laboratory for Bio-Nanotechnology and Molecular Engineering of Hunan
Province, Hunan University, Changsha 410082, People’s Republic of China
| | - Min Ou
- State Key Laboratory of Chemo/Biosensing
and Chemometrics, College of Chemistry and Chemical Engineering, Key
Laboratory for Bio-Nanotechnology and Molecular Engineering of Hunan
Province, Hunan University, Changsha 410082, People’s Republic of China
| | - Qifeng Zhou
- State Key Laboratory of Chemo/Biosensing
and Chemometrics, College of Chemistry and Chemical Engineering, Key
Laboratory for Bio-Nanotechnology and Molecular Engineering of Hunan
Province, Hunan University, Changsha 410082, People’s Republic of China
| | - Kemin Wang
- State Key Laboratory of Chemo/Biosensing
and Chemometrics, College of Chemistry and Chemical Engineering, Key
Laboratory for Bio-Nanotechnology and Molecular Engineering of Hunan
Province, Hunan University, Changsha 410082, People’s Republic of China
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29
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Jin F, Zheng J, Liu C, Yang S, Li Y, Li J, Lian Y, Yang R. Dual-stimuli responsive i-motif/nanoflares for sensing ATP in lysosomes. Analyst 2015; 139:3714-7. [PMID: 24905584 DOI: 10.1039/c4an00153b] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A dual-stimuli responsive i-motif/nanoflare for molecule detection in lysosomes was designed. By combining the structure-switchable i-motif sequence and high recognition ability of an adenosine triphosphate (ATP) aptamer, subcellular sensing and visualization sensing of ATP in lysosomes at the subcellular level can be achieved. This general sensing technique can be applied for a broad range of cellular communication studies to improve our understanding of subcellular signaling and function.
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Affiliation(s)
- Fen Jin
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, P. R. China
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30
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Cao Y, Qin Y, Bruist M, Gao S, Wang B, Wang H, Guo X. Formation and Dissociation of the Interstrand i-Motif by the Sequences d(XnC 4Y m) Monitored with Electrospray Ionization Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2015; 26:994-1003. [PMID: 25862186 DOI: 10.1007/s13361-015-1093-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Revised: 02/05/2015] [Accepted: 02/06/2015] [Indexed: 06/04/2023]
Abstract
Formation and dissociation of the interstrand i-motifs by DNA with the sequence d(X(n)C(4)Y(m)) (X and Y represent thymine, adenine, or guanine, and n, m range from 0 to 2) are studied with electrospray ionization mass spectrometry (ESI-MS), circular dichroism (CD), and UV spectrophotometry. The ion complexes detected in the gas phase and the melting temperatures (Tm) obtained in solution show that a non-C base residue located at 5' end favors formation of the four-stranded structures, with T > A > G for imparting stability. Comparatively, no rule is found when a non-C base is located at the 3' end. Detection of penta- and hexa-stranded ions indicates the formation of i-motifs with more than four strands. In addition, the i-motifs seen in our mass spectra are accompanied by single-, double-, and triple-stranded ions, and the trimeric ions were always less abundant during annealing and heat-induced dissociation process of the DNA strands in solution (pH = 4.5). This provides a direct evidence of a strand-by-strand formation and dissociation pathway of the interstrand i-motif and formation of the triple strands is the rate-limiting step. In contrast, the trimeric ions are abundant when the tetramolecular ions are subjected to collision-induced dissociation (CID) in the gas phase, suggesting different dissociation behaviors of the interstrand i-motif in the gas phase and in solution. Furthermore, hysteretic UV absorption melting and cooling curves reveal an irreversible dissociation and association kinetic process of the interstrand i-motif in solution.
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Affiliation(s)
- Yanwei Cao
- College of Chemistry, Jilin University, Changchun, 130012, People's Republic of China
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31
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Mata G, Luedtke NW. Fluorescent Probe for Proton-Coupled DNA Folding Revealing Slow Exchange of i-Motif and Duplex Structures. J Am Chem Soc 2015; 137:699-707. [DOI: 10.1021/ja508741u] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Guillaume Mata
- Department of Chemistry, University of Zürich, Winterthurerstrasse
190, CH-8057 Zürich, Switzerland
| | - Nathan W. Luedtke
- Department of Chemistry, University of Zürich, Winterthurerstrasse
190, CH-8057 Zürich, Switzerland
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32
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Garcia M, Kempe K, Haddleton DM, Khan A, Marsh A. Templated polymerizations on solid supports mediated by complementary nucleoside interactions. Polym Chem 2015. [DOI: 10.1039/c4py01783h] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The preparation of immobilized poly(methacryloyl nucleosides) and their abilities for template polymerizations is discussed.
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Affiliation(s)
| | | | | | - Afzal Khan
- Department of Chemistry
- University of Warwick
- Coventry
- UK
| | - Andrew Marsh
- Department of Chemistry
- University of Warwick
- Coventry
- UK
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33
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Chen YW, Jhan CR, Neidle S, Hou MH. Structural Basis for the Identification of an i-Motif Tetraplex Core with a Parallel-Duplex Junction as a Structural Motif in CCG Triplet Repeats. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201405637] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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34
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Chen YW, Jhan CR, Neidle S, Hou MH. Structural basis for the identification of an i-motif tetraplex core with a parallel-duplex junction as a structural motif in CCG triplet repeats. Angew Chem Int Ed Engl 2014; 53:10682-6. [PMID: 25139267 DOI: 10.1002/anie.201405637] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Indexed: 11/12/2022]
Abstract
CCG triplet repeats can fold into tetraplex structures, which are associated with the expansion of (CCG)n trinucleotide sequences in certain neurological diseases. These structures are stabilized by intertwining i-motifs. However, the structural basis for tetraplex i-motif formation in CCG triplet repeats remains largely unknown. We report the first crystal structure of a CCG-repeat sequence, which shows that two dT(CCG)3 A strands can associate to form a tetraplex structure with an i-motif core containing four C:C(+) pairs flanked by two G:G homopurine base pairs as a structural motif. The tetraplex core is attached to a short parallel-stranded duplex. Each hairpin itself contains a central CCG loop in which the nucleotides are flipped out and stabilized by stacking interactions. The helical twists between adjacent cytosine residues of this structure in the i-motif core have an average value of 30°, which is greater than those previously reported for i-motif structures.
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Affiliation(s)
- Yi-Wen Chen
- Institute of Genomics and Bioinformatics and Institute of Biochemistry, National Chung Hsing University, No. 250 Kuo-Kuang Road, Taichung (Taiwan)
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Abstract
CONSPECTUS: Most biological processes happen at the nanometer scale, and understanding the energy transformations and material transportation mechanisms within living organisms has proved challenging. To better understand the secrets of life, researchers have investigated artificial molecular motors and devices over the past decade because such systems can mimic certain biological processes. DNA nanotechnology based on i-motif structures is one system that has played an important role in these investigations. In this Account, we summarize recent advances in functional DNA nanotechnology based on i-motif structures. The i-motif is a DNA quadruplex that occurs as four stretches of cytosine repeat sequences form C·CH(+) base pairs, and their stabilization requires slightly acidic conditions. This unique property has produced the first DNA molecular motor driven by pH changes. The motor is reliable, and studies show that it is capable of millisecond running speeds, comparable to the speed of natural protein motors. With careful design, the output of these types of motors was combined to drive micrometer-sized cantilevers bend. Using established DNA nanostructure assembly and functionalization methods, researchers can easily integrate the motor within other DNA assembled structures and functional units, producing DNA molecular devices with new functions such as suprahydrophobic/suprahydrophilic smart surfaces that switch, intelligent nanopores triggered by pH changes, molecular logic gates, and DNA nanosprings. Recently, researchers have produced motors driven by light and electricity, which have allowed DNA motors to be integrated within silicon-based nanodevices. Moreover, some devices based on i-motif structures have proven useful for investigating processes within living cells. The pH-responsiveness of the i-motif structure also provides a way to control the stepwise assembly of DNA nanostructures. In addition, because of the stability of the i-motif, this structure can serve as the stem of one-dimensional nanowires, and a four-strand stem can provide a new basis for three-dimensional DNA structures such as pillars. By sacrificing some accuracy in assembly, we used these properties to prepare the first fast-responding pure DNA supramolecular hydrogel. This hydrogel does not swell and cannot encapsulate small molecules. These unique properties could lead to new developments in smart materials based on DNA assembly and support important applications in fields such as tissue engineering. We expect that DNA nanotechnology will continue to develop rapidly. At a fundamental level, further studies should lead to greater understanding of the energy transformation and material transportation mechanisms at the nanometer scale. In terms of applications, we expect that many of these elegant molecular devices will soon be used in vivo. These further studies could demonstrate the power of DNA nanotechnology in biology, material science, chemistry, and physics.
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Affiliation(s)
- Yuanchen Dong
- Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Zhongqiang Yang
- Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Dongsheng Liu
- Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, China
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36
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Day HA, Pavlou P, Waller ZAE. i-Motif DNA: structure, stability and targeting with ligands. Bioorg Med Chem 2014; 22:4407-18. [PMID: 24957878 DOI: 10.1016/j.bmc.2014.05.047] [Citation(s) in RCA: 262] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 05/09/2014] [Accepted: 05/22/2014] [Indexed: 10/25/2022]
Abstract
i-Motifs are four-stranded DNA secondary structures which can form in sequences rich in cytosine. Stabilised by acidic conditions, they are comprised of two parallel-stranded DNA duplexes held together in an antiparallel orientation by intercalated, cytosine-cytosine(+) base pairs. By virtue of their pH dependent folding, i-motif forming DNA sequences have been used extensively as pH switches for applications in nanotechnology. Initially, i-motifs were thought to be unstable at physiological pH, which precluded substantial biological investigation. However, recent advances have shown that this is not always the case and that i-motif stability is highly dependent on factors such as sequence and environmental conditions. In this review, we discuss some of the different i-motif structures investigated to date and the factors which affect their topology, stability and dynamics. Ligands which can interact with these structures are necessary to aid investigations into the potential biological functions of i-motif DNA and herein we review the existing i-motif ligands and give our perspective on the associated challenges with targeting this structure.
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Affiliation(s)
- Henry A Day
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich, Norfolk NR4 7TJ, UK
| | - Pavlos Pavlou
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich, Norfolk NR4 7TJ, UK
| | - Zoë A E Waller
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich, Norfolk NR4 7TJ, UK.
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37
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Ung HU, Moehlig AR, Kudla RA, Mueller LJ, Oomens J, Berden G, Morton TH. Proton-bound dimers of 1-methylcytosine and its derivatives: vibrational and NMR spectroscopy. Phys Chem Chem Phys 2014; 15:19001-12. [PMID: 24096726 DOI: 10.1039/c3cp52260a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Vibrational spectroscopy and NMR demonstrate that the proton-bound dimer of 1-methylcytosine, 1, has an unsymmetrical structure at room temperature. In the gas phase, investigation of isolated homodimer 1 reveals five fundamental NH vibrations by IR Multiple Photon Dissociation (IRMPD) action spectroscopy. The NH···N stretching vibration between the two ring nitrogens exhibits a frequency of 1570 cm(-1), as confirmed by examination of the proton-bound homodimers of 5-fluoro-1-methycytosine, 2, and of 1,5-dimethylcytosine, 3, which display absorptions in the same region that disappear upon deuterium substitution. (13)C, and (15)N NMR of the solid iodide salt of 1 confirm the nonequivalence of the two rings in the anhydrous proton-bound homodimer at room temperature. IRMPD spectra of the three possible heterodimers also show NH···N stretches in the same domain, and at least one of the heterodimers, the proton-bound dimer of 1,5-dimethylcytosine with 1-methylcytosine, exhibits two bands suggestive of the presence of two tautomers close in energy.
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Affiliation(s)
- Hou U Ung
- Department of Chemistry, University of California, Riverside, CA 92521-0403, USA.
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38
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Benabou S, Aviñó A, Eritja R, González C, Gargallo R. Fundamental aspects of the nucleic acid i-motif structures. RSC Adv 2014. [DOI: 10.1039/c4ra02129k] [Citation(s) in RCA: 129] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The latest research on fundamental aspects of i-motif structures is reviewed with special attention to their hypothetical rolein vivo.
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Affiliation(s)
- S. Benabou
- Department of Analytical Chemistry
- University of Barcelona
- E-08028 Barcelona, Spain
| | - A. Aviñó
- Institute for Advanced Chemistry of Catalonia (IQAC-CSIC)
- CIBER-BBN Networking Centre on Bioengineering
- Biomaterials and Nanomedicine
- E-08034 Barcelona, Spain
| | - R. Eritja
- Institute for Advanced Chemistry of Catalonia (IQAC-CSIC)
- CIBER-BBN Networking Centre on Bioengineering
- Biomaterials and Nanomedicine
- E-08034 Barcelona, Spain
| | - C. González
- Institute of Physical Chemistry “Rocasolano”
- CSIC
- E-28006 Madrid, Spain
| | - R. Gargallo
- Department of Analytical Chemistry
- University of Barcelona
- E-08028 Barcelona, Spain
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39
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Wang C, Du Y, Wu Q, Xuan S, Zhou J, Song J, Shao F, Duan H. Stimuli-responsive plasmonic core-satellite assemblies: i-motif DNA linker enabled intracellular pH sensing. Chem Commun (Camb) 2013; 49:5739-41. [PMID: 23680788 DOI: 10.1039/c3cc80005a] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report stimuli-responsive core-satellite assemblies of binary gold nanoparticles, linked by i-motif DNA, for live cell plasmonic imaging of pH changes in the endocytic pathway.
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Affiliation(s)
- Chenxu Wang
- School of Chemical and Biomedical Engineering, Nanyang Technological University, 70 Nanyang Drive, Singapore 637457
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40
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Nesterova IV, Elsiddieg SO, Nesterov EE. Design and evaluation of an i-motif-based allosteric control mechanism in DNA-hairpin molecular devices. J Phys Chem B 2013; 117:10115-21. [PMID: 23941235 DOI: 10.1021/jp405230g] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Molecular devices designed to assess and manipulate biologically relevant conditions with required accuracy and precision play an essential role in life sciences research. Incorporating allosteric regulation mechanism is an attractive strategy toward more efficient artificial sensing and switching systems. Herein, we report on a new principle of regulating switching parameters of a DNA-based molecular device based on allosteric interaction between spatially separated hairpin stem and a tetraplexed fragment (i.e., i-motif). We characterized thermodynamic and kinetic effects arising from interaction between functional domains of the device and demonstrated the potential of applying the allosteric control principle for rational design of sensors and switches with precisely defined operational characteristics.
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Affiliation(s)
- Irina V Nesterova
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
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Mládek A, Krepl M, Svozil D, Čech P, Otyepka M, Banáš P, Zgarbová M, Jurečka P, Šponer J. Benchmark quantum-chemical calculations on a complete set of rotameric families of the DNA sugar–phosphate backbone and their comparison with modern density functional theory. Phys Chem Chem Phys 2013; 15:7295-310. [DOI: 10.1039/c3cp44383c] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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42
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Abstract
Carbon-oxygen (CH···O) hydrogen bonding represents an unusual category of molecular interactions first documented in biological structures over 4 decades ago. Although CH···O hydrogen bonding has remained generally underappreciated in the biochemical literature, studies over the last 15 years have begun to yield direct evidence of these interactions in biological systems. In this minireview, we provide a historical context of biological CH···O hydrogen bonding and summarize some major advancements from experimental studies over the past several years that have elucidated the importance, prevalence, and functions of these interactions. In particular, we examine the impact of CH···O bonds on protein and nucleic acid structure, molecular recognition, and enzyme catalysis and conclude by exploring overarching themes and unresolved questions regarding unconventional interactions in biomolecular structure.
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43
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Mei H, Budow S, Seela F. Construction and assembly of chimeric DNA: oligonucleotide hybrid molecules composed of parallel or antiparallel duplexes and tetrameric i-motifs. Biomacromolecules 2012; 13:4196-204. [PMID: 23121010 DOI: 10.1021/bm301471d] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Chimeric DNA containing parallel (ps) and antiparallel (aps) duplex elements as well as poly-dC tracts were designed and synthesized. Oligonucleotide duplexes with ps chain orientation containing reverse Watson-Crick dA-dT base pairs and short d(C)2 tails are stabilized under slightly acidic conditions by hemiprotonated dCH+-dC base pairs ("clamp" effect). Corresponding molecules with aps orientation containing Watson-Crick dA-dT base pairs do not show this phenomenon. Chimeric DNA with ps duplex elements and long d(C)5 tails at one or at both ends assemble to tetrameric i-motif structures. Molecules with two terminal d(C)5 tails form multimeric assemblies which have the potential to form nanoscopic scaffolds. A preorganization of the ps duplex chains stabilizes the i-motif assemblies up to almost neutral conditions as evidenced by thermal melting and gel electrophoresis. Although, ps DNA is generally less stable than aps DNA, the aps duplexes contribute less to the stability of the i-motif than ps DNA.
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Affiliation(s)
- Hui Mei
- Laboratory of Bioorganic Chemistry and Chemical Biology, Center for Nanotechnology, Heisenbergstraße 11, 48149 Münster, Germany
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Nakano SI, Oka H, Yamaguchi D, Fujii M, Sugimoto N. Base-pairing selectivity of a ureido-linked phenyl-2'-deoxycytidine derivative. Org Biomol Chem 2012; 10:9664-70. [PMID: 23147647 DOI: 10.1039/c2ob26897c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Incorporation of modified nucleotides into nucleic acid strands often produces conformational constraints and steric hindrances that may change the property of base pairing. In this study, we investigated a 2'-deoxycytidine derivative that tethers a phenyl moiety to the exocyclic amino group of cytosine linked through a ureido group. This derivative compound is structurally similar to the carbamoylated DNA base lesions produced in cells. The thermodynamic and structural studies showed that the modified dC formed the base pair with dG in the complementary strand, but the base-pairing selectivity toward dG was decreased under poly(ethylene glycol)-mediated osmotic stress. The phenyl group and the ureido linker attached to dC provided selectivity for the formation of base pairing exclusively with dG in a wide range of pH conditions, whereas unmodified dC stabilized the pairings with dA or dC in acidic solutions. Moreover, this modified base could not form self-pairing through intermolecular hydrogen bonds. We suggest that formation of weak pairing and protonation of the cytosine base are hindered due to the base modification. These data provide insights into the pairing selectivity of carbamoylated cytosine lesions produced in cells, and suggest applications of the 2'-deoxycytidine derivatives in medical technologies, molecular biology experiments, and synthesis of a supramolecular network of DNA strands.
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Affiliation(s)
- Shu-ichi Nakano
- Faculty of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, 7-1-20, Minatojima-minamimachi, Kobe 650-0047, Japan.
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45
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Abstract
The physicochemical properties of small molecules as well as macromolecules are modulated by solution pH, and DNA is no exception. Special sequences of DNA can adopt unusual conformations e.g., triplex, i-motif and A-motif, depending on solution pH. The specific range of pH for these unusual structures is dictated by the pKa of protonation of the relevant nucleobase involved in the resultant non-canonical base pairing that is required to stabilise the structure. The biological significance of these pH-dependent structures is not yet clear. However, these non-B-DNA structures have been used to design different devices to direct chemical reactions, generate mechanical force, sense pH, etc. The performance of these devices can be monitored by a photonic signal. They are autonomous and their ‘waste free’ operation cycles makes them highly processive. Applications of these devices help to increase understanding of the structural polymorphism of the motifs themselves. The design of these devices has continuously evolved to improve their performance efficiency in different contexts. In some examples, these devices have been shown to perform inside complex living systems with similar efficiencies, to report on the chemical environment there. The robust performance of these devices opens up exciting possibilities for pH-sensitive DNA devices in the study of various pH-regulated biological events.
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Affiliation(s)
- Sonali Saha
- National Centre for Biological Sciences TIFR, GKVK, Bellary Road, Bangalore 560065 India
| | - Yamuna Krishnan*
- National Centre for Biological Sciences TIFR, GKVK, Bellary Road, Bangalore 560065 India
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46
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Intramolecular folding in human ILPR fragment with three C-rich repeats. PLoS One 2012; 7:e39271. [PMID: 22761750 PMCID: PMC3382603 DOI: 10.1371/journal.pone.0039271] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Accepted: 05/22/2012] [Indexed: 11/19/2022] Open
Abstract
Enrichment of four tandem repeats of guanine (G) rich and cytosine (C) rich sequences in functionally important regions of human genome forebodes the biological implications of four-stranded DNA structures, such as G-quadruplex and i-motif, that can form in these sequences. However, there have been few reports on the intramolecular formation of non-B DNA structures in less than four tandem repeats of G or C rich sequences. Here, using mechanical unfolding at the single-molecule level, electrophoretic mobility shift assay (EMSA), circular dichroism (CD), and ultraviolet (UV) spectroscopy, we report an intramolecularly folded non-B DNA structure in three tandem cytosine rich repeats, 5'-TGTC4ACAC4TGTC4ACA (ILPR-I3), in the human insulin linked polymorphic region (ILPR). The thermal denaturation analyses of the sequences with systematic C to T mutations have suggested that the structure is linchpinned by a stack of hemiprotonated cytosine pairs between two terminal C4 tracts. Mechanical unfolding and Br(2) footprinting experiments on a mixture of the ILPR-I3 and a 5'-C4TGT fragment have further indicated that the structure serves as a building block for intermolecular i-motif formation. The existence of such a conformation under acidic or neutral pH complies with the strand-by-strand folding pathway of ILPR i-motif structures.
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47
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Yang Y, Sun Y, Yang Y, Xing Y, Zhang T, Wang Z, Yang Z, Liu D. Influence of Tetra(ethylene glycol) (EG4) Substitution at the Loop Region on the Intramolecular DNA i-Motif. Macromolecules 2012. [DOI: 10.1021/ma300230q] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yuhe Yang
- Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Yawei Sun
- National Center for Nanoscience and Technology, Beijing 100190, China
| | - Yang Yang
- National Center for Nanoscience and Technology, Beijing 100190, China
| | - Yongzheng Xing
- Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, China
- National Center for Nanoscience and Technology, Beijing 100190, China
| | - Tao Zhang
- Department of Chemistry, Renmin University of China, Beijing 100872, China
| | - Zeming Wang
- Department of Chemistry, University of Science and Technology of China, Hefei
230026, China
| | - Zhongqiang Yang
- Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Dongsheng Liu
- Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, China
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48
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Buck HM. DNA systems for B-Z transition and their significance as epigenetic model: the fundamental role of the methyl group. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2012; 30:918-44. [PMID: 22060556 DOI: 10.1080/15257770.2011.620580] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
Abstract
Epigenetic systems involved in the dynamics of gene expression, which are fundamental to cell determination and function without alteration in DNA sequences, are based on methylation of the N-terminal tails of lysine residues and DNA methylation. We demonstrate the vital importance for genetic transfer by different (hydrogen) networks, suggesting a complex interaction between the two epigenetic modifications. In other words, the methylation of local lysines can prescribe C(P)G methylation, which requires that methylation of histones and DNA are cooperative in carrying out an epigenetic instruction for integrating gene-silencing networks. To give a bio-organic description of the epigenetic coherence between histone and base methylation, we used the well-known B- into Z-DNA dynamics in combination with the unique properties of phosphatemethylated DNA on different levels of chemistry.
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Guittet E, Renciuk D, Leroy JL. Junctions between i-motif tetramers in supramolecular structures. Nucleic Acids Res 2012; 40:5162-70. [PMID: 22362739 PMCID: PMC3367196 DOI: 10.1093/nar/gks161] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The symmetry of i-motif tetramers gives to cytidine-rich oligonucleotides the capacity to associate into supramolecular structures (sms). In order to determine how the tetramers are linked together in such structures, we have measured by gel filtration chromatography and NMR the formation and dissociation kinetics of sms built by oligonucleotides containing two short C stretches separated by a non-cytidine-base. We show that a stretch of only two cytidines either at the 3'- or 5'-end is long enough to link the tetramers into sms. The analysis of the properties of sms formed by oligonucleotides differing by the length of the oligo-C stretches, the sequence orientation and the nature of the non-C base provides a model of the junction connecting the tetramers in sms.
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Affiliation(s)
- Eric Guittet
- Laboratoire de Chimie et Biologie Structurales, Institut de Chimie des Substances Naturelles, Gif-sur-Yvette, France
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50
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Mao Y, Zhang J. Understanding thermodynamic competitivity between biopolymer folding and misfolding under large-scale intermolecular interactions. J Am Chem Soc 2011; 134:631-9. [PMID: 22126310 DOI: 10.1021/ja209534c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cooperativity is a hallmark of spontaneous biopolymer folding. The presence of intermolecular interactions could create off-pathway misfolding structures and suppress folding cooperativity. This raises the hypothesis that thermodynamic competitivity between off-pathway misfolding and on-pathway folding may intervene with cooperativity and govern biopolymer folding dynamics under conditions permitting large-scale intermolecular interactions. Here we report direct imaging and theoretical modeling of thermodynamic competitivity between biopolymer folding and misfolding under such conditions, using a two-dimensional array of proton-fueled DNA molecular motors packed at the maximal density as a model system. Time-resolved liquid-phase atomic force microscopy with enhanced phase contrast revealed that the misfolding and folding intermediates transiently self-organize into spatiotemporal patterns on the nanoscale in thermodynamic states far away from equilibrium as a result of thermodynamic competitivity. Computer simulations using a novel cellular-automaton network model provide quantitative insights into how large-scale intermolecular interactions correlate the structural dynamics of individual biomolecules together at the systems level.
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Affiliation(s)
- Youdong Mao
- Dana-Farber Cancer Institute, Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts 02215, USA.
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